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1
Thirumurthi, Ramalingaigh Dhandapani, and William C. Hart. "Chemistry of Bulk Precipitation in Halifax and its Effects on Chain and Chocolate Lakes." Water Quality Research Journal 20, no. 1 (February 1, 1985): 89–105. http://dx.doi.org/10.2166/wqrj.1985.008.
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Abstract Fifty-nine weekly bulk deposition samples and about 1100 lake water samples from the study area were analyzed for water quality parameters to document the bulk deposition chemistry and its effects on Chain and Chocolate Lakes. The composition of bulk deposition in Halifax (on chemical equivalent basis) was: chloride, 28 % of total ions; sodium, 25% sulfate, 15%; hydrogen, 14%; calcium, 6%; total nitrogen, 6%; magnesium, 4%; nitrate(N), 2%; ammonia(N), 1%; total phosphorus, 0.06%; and orthophosphorus, 0.03%. Marine sources contributed almost all of chloride and magnesium, 97% of sodium, 17% of sulfate, and 13% of calcium. Bulk deposition was not the major source of sodium, chloride, sulfate, calcium, magnesium, hydrogen, nitrogen, and phosphorus to the study lakes. However, it was the principal source of hydrogen, nitrogen, and total phosphorus to the forested watersheds of Chain Lakes, and of hydrogen, orthophosphorus and total phosphorus to the urbanized watershed of Chocolate Lake. The effects of these ions were not reflected in the lakes' water quality, probably because of the excess alkalinity produced in the watersheds of Chain Lakes, and also because of high flushing rates of the lakes.
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McCarty, James A., Marty D. Matlock, J. Thad Scott, and Brian E. Haggard. "Risk Indicators for Identifying Critical Source Areas in Five Arkansas Watersheds." Transactions of the ASABE 61, no. 3 (2018): 1025–32. http://dx.doi.org/10.13031/trans.12699.
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Abstract. Change point analysis was used to explore the interactions between watershed characteristics and concentrations of nitrate-nitrogen, total nitrogen, soluble reactive phosphorus, and total phosphorus in streams within the Ozark Highlands, Arkansas Valley, and Ouachita Mountains ecoregions of Arkansas. Thresholds were identified for multiple watershed metrics used to predict water quality, including percent forest in the catchment, agricultural and forested land use in the riparian buffer, stream density, and poultry house density. Based on the observed relationships from the sampled watersheds, we propose four risk indicators to improve the identification of critical source areas for NPS pollution mitigation: subwatersheds that have less than 50% forested area within the drainage area, less than 50% forested area in the riparian buffer zone, more than 0.9 poultry houses km-2, and a stream density that exceeds 50 m ha-1. Keywords: Nonpoint-source pollution, Source water protection, Watershed management.
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Lee, J. H., M. J. Yu, K. W. Bang, and J. S. Choe. "Evaluation of the methods for first flush analysis in urban watersheds." Water Science and Technology 48, no. 10 (November 1, 2003): 167–76. http://dx.doi.org/10.2166/wst.2003.0566.
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The general tendency between the ratio of cumulative pollutant loads and the ratio of cumulative runoff appears as a nonlinear form which can be expressed in the form of a third polynomial. In this paper third degree polynomials were applied to represent the first flush curves based on the relationship between the cumulative pollutant load ratio and cumulative runoff ratio. The quantity of stormwater runoff and quality constituents, including chemical oxygen demand (COD), suspended solids (SS), total Kjeldahl nitrogen (TKN), ortho-phosphorus (PO4-P), total phosphorus (TP), n-hexane extracts (HEM), and iron (Fe) were analysed. The objectives of this study were (1) to characterize the quality of stormwater runoff (2) in order to analyse the cumulative curve area ratio and to calculate the first flush coefficients, (3) while also representing the first flush with a third polynomial equation.
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Pueppke, Steven G., Wangshou Zhang, Hengpeng Li, Dongqiang Chen, and Weixin Ou. "An Integrative Framework to Control Nutrient Loss: Insights from Two Hilly Basins in China’s Yangtze River Delta." Water 11, no. 10 (September 29, 2019): 2036. http://dx.doi.org/10.3390/w11102036.
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Rapid economic development and population growth in China’s Yangtze River Delta (YRD) are exerting significant environmental pressure on the region’s land and water, especially in hilly areas where many drinking water reservoirs have been constructed. These areas, which are characterized by steep slopes and thin soils, provide critical services, including flood control, water resource supply, food production, and recreational opportunities for nearby highly developed and heavily populated areas of the delta. We contrast two of these areas—the well-studied Tianmu Lake watershed and the much larger Qiandao Lake watershed. Both face similar challenges from nitrogen and phosphorus pollution due to rapid socio-economic development, but differences in watershed size and distinctions related to political boundaries influence the range of approaches available to maintain water quality. We review experiences of controlling nutrient pollution in these watersheds as case studies, and based on that information, propose an integrated framework to minimize nitrogen and phosphorus pollution in similarly challenged watersheds. The framework, which is designed to be generalizable rather than prescriptive, emphasizes source control, delivery interception, and fate management of nutrients.
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Carey, Richard O., George J. Hochmuth, Christopher J. Martinez, Treavor H. Boyer, Vimala D. Nair, Michael D. Dukes, Gurpal S. Toor, et al. "A Review of Turfgrass Fertilizer Management Practices: Implications for Urban Water Quality." HortTechnology 22, no. 3 (June 2012): 280–91. http://dx.doi.org/10.21273/horttech.22.3.280.
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Urban watersheds include extensive turfgrass plantings that are associated with anthropocentric attitudes toward landscapes. Native and construction-disturbed urban soils often cannot supply adequate amounts of nitrogen (N) and phosphorus (P) for the growth and beauty of landscape plants. Hence, fertilization of landscape plants is practiced. Mismanaged fertilization and irrigation practices represent a potential source of nutrients that may contribute to water quality impairment. This review focuses on turfgrass fertilization practices and their impacts on urban water quality. Research results show that fertilization during active growth periods enhances turfgrass nutrient uptake efficiencies. The major concern regarding the fertilization of turfgrass and landscape plants in urban watersheds, therefore, is selecting the proper combination of fertilizer rate, timing, and placement that maximizes nutrient utilization efficiency and reduces the risk for nutrient loss to water bodies. Encouraging individuals to adopt best management practices (BMPs) is a priority for watershed managers. Research has found that educational programs are an important part of changing fertilization habits and that education needs to be thorough and comprehensive, which is beyond the scope of many seminars and fact sheets currently in use.
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Lee, Jong-Won, Sang-Woo Lee, Kyung-Jin An, Soon-Jin Hwang, and Nan-Young Kim. "An Estimated Structural Equation Model to Assess the Effects of Land Use on Water Quality and Benthic Macroinvertebrates in Streams of the Nam-Han River System, South Korea." International Journal of Environmental Research and Public Health 17, no. 6 (March 23, 2020): 2116. http://dx.doi.org/10.3390/ijerph17062116.
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The extent of anthropogenic land use in watersheds determines the amount of pollutants discharged to streams. This indirectly and directly affects stream water quality and biological health. Most studies have therefore focused on ways to reduce non-point pollution sources to streams from the surrounding land use in watersheds. However, the mechanistic pathways between land use and the deterioration of stream water quality and biological assemblages remain unclear. This study estimated a structural equation model (SEM) representing the impact of agricultural and urban land use on water quality and the benthic macroinvertebrate index (BMI) using IBM AMOS in the Nam-Han river systems, South Korea. The estimated SEM showed that the percent of urban and agricultural land in the watersheds significantly affected both the water quality and the BMI of the streams. Specifically, a higher percent of urban land use had directly increased the biochemical oxygen demand (BOD) and total phosphorus (TP), and deteriorated the BMI of streams. Similarly, higher proportions of agricultural land use had also directly increased the BOD, total nitrogen (TN), and total phosphorus (TP) concentrations, and lowered the BMI of streams. In addition, it was observed that the percent of urban and agricultural land use had indirectly deteriorated the BMI through increased BOD. However, we were not able to observe any significant indirect effect of the percent of urban and agricultural land use through increased nutrients including TN and TP. These results indicate that increased urban and agricultural land use in the watersheds had directly and indirectly affected the physicochemical characteristics and benthic macroinvertebrate communities in streams. Our findings emphasize the need to develop more elaborate environmental management and restoration strategies to improve the water quality and biological status of streams.
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Chambers, P. A., G. A. Benoy, R. B. Brua, and J. M. Culp. "Application of nitrogen and phosphorus criteria for streams in agricultural landscapes." Water Science and Technology 64, no. 11 (December 1, 2011): 2185–91. http://dx.doi.org/10.2166/wst.2011.760.
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Efforts to control eutrophication of water resources in agriculturally dominated ecosystems have focused on managing on-farm activities to reduce nutrient loss; however, another management measure for improving water quality is adoption of environmental performance criteria (or ‘outcome-based standards’). Here, we review approaches for setting environmental quality criteria for nutrients, summarize approaches developed in Canada for setting ‘ideal’ and ‘achievable’ nutrient criteria for streams in agricultural watersheds, and consider how such criteria could be applied. As part of a ‘National Agri-Environmental Standards Initiative’, the Government of Canada committed to the development of non-regulatory environmental performance standards that establish total P (TP) and total N (TN) concentrations to protect ecological condition of agricultural streams. Application of four approaches for defining ideal standards using only chemistry data resulted in values for TP and TN spanning a relatively narrow range of concentrations within a given ecoregion. Cross-calibration of these chemically derived standards with information on biological condition resulted in recommendations for TP and TN that would likely protect aquatic life from adverse effects of eutrophication. Non-point source water quality modelling was then conducted in a specific watershed to estimate achievable standards, i.e. chemical conditions that could be attained using currently available and recommended management practices. Our research showed that, taken together, short-term achievable standards and ultimate ideal standards could be used to set policy targets that should, if realized, lower N and P concentrations in Canadian agricultural streams and improve biotic condition.
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Sekar, Raju, Xin Jin, Shuang Liu, Jing Lu, Jianwei Shen, Yingya Zhou, Ziyang Gong, Xueying Feng, Shengjie Guo, and Wenlong Li. "Fecal Contamination and High Nutrient Levels Pollute the Watersheds of Wujiang, China." Water 13, no. 4 (February 10, 2021): 457. http://dx.doi.org/10.3390/w13040457.
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Freshwaters in China are affected by point and non-point sources of pollution. The Wujiang District (Suzhou City, China) has a long history of canals, rivers, and lakes that are currently facing various water quality issues. In this study, the water quality of four rivers and a lake in Wujiang was assessed to quantify pollution and explore its causes. Seventy-five monthly samples were collected from these water bodies (five locations/samples per area) from August to October 2020 and were compared with nine control samples collected from a water protection area. Fifteen physicochemical, microbiological, and molecular–microbiological parameters were analyzed, including nutrients, total and fecal coliforms, and fecal markers. Significant monthly variation was observed for most parameters at all areas. Total phosphorus, phosphates, total nitrogen, ammonium–nitrogen, and fecal coliforms mostly exceeded the acceptable limits set by the Chinese Ministry of Environmental Protection. The LiPuDang Lake and the WuFangGang River were the most degraded areas. The studied parameters were correlated with urban, agricultural, industrial, and other major land use patterns. The results suggest that fecal contamination and nutrients, associated with certain land use practices, are the primary pollution factors in the Wujiang District. Detailed water quality monitoring and targeted management strategies are necessary to control pollution in Wujiang’s watersheds.
9
Taylor, Milton D., Sarah A. White, Stephen J. Klaine, and Ted Whitwell. "(102) Monitoring Nutrient Mitigation at a Container Nursery Wetland: A 3-Year Study." HortScience 40, no. 4 (July 2005): 1049A—1049. http://dx.doi.org/10.21273/hortsci.40.4.1049a.
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Container-grown plants require large amounts of water and nutrients during their production cycle. This results in substantial runoff that is contaminated with nitrogen and phosphorus. At our study site, nutrients were delivered through incorporation in the potting media as timed-release prills and through liquid feeding by injection into irrigation water. Mitigation of nutrients in runoff water was dealt with proactively by the container nursery with construction of 3.77 ha of planted wetlands to receive runoff from a 48.6-ha drainage basin and excess water diverted from adjacent watersheds. Water flowed though drains between wetland cells and eventually into stilling ponds before it was allowed to exit the property. Water flow through the wetlands ranged from 1.1 to 3.1 million liters per day over the period. Three years of monitoring data indicate some seasonal differences in nitrogen removal efficiencies. Nitrogen removal between March and November averaged ≥95% while removal during winter (December through February) averaged ≥72%. Nitrogen (as nitrate) varied from 4.28 ppm to ≤0.01 ppm in wetland discharge, well below drinking water quality standards, but occasionally above levels that may cause downstream eutrophication. Orthophosphate phosphorus removal was highly variable with greatest removal occurring during late spring, late fall, and winter. There was a significant net export of phosphorus during some summer months for years 2 and 3. Phosphorus levels in wetland discharge ranged between 0.84 and 2.75 ppm. While there is currently no legal water quality standard for phosphorus, these levels were above the generally accepted level for preventing downstream eutrophication.
10
McDonald, Robert I., Katherine F. Weber, Julie Padowski, Tim Boucher, and Daniel Shemie. "Estimating watershed degradation over the last century and its impact on water-treatment costs for the world’s large cities." Proceedings of the National Academy of Sciences 113, no. 32 (July 25, 2016): 9117–22. http://dx.doi.org/10.1073/pnas.1605354113.
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Urban water systems are impacted by land use within their source watersheds, as it affects raw water quality and thus the costs of water treatment. However, global estimates of the effect of land cover change on urban water-treatment costs have been hampered by a lack of global information on urban source watersheds. Here, we use a unique map of the urban source watersheds for 309 large cities (population > 750,000), combined with long-term data on anthropogenic land-use change in their source watersheds and data on water-treatment costs. We show that anthropogenic activity is highly correlated with sediment and nutrient pollution levels, which is in turn highly correlated with treatment costs. Over our study period (1900–2005), median population density has increased by a factor of 5.4 in urban source watersheds, whereas ranching and cropland use have increased by a factor of 3.4 and 2.0, respectively. Nearly all (90%) of urban source watersheds have had some level of watershed degradation, with the average pollutant yield of urban source watersheds increasing by 40% for sediment, 47% for phosphorus, and 119% for nitrogen. We estimate the degradation of watersheds over our study period has impacted treatment costs for 29% of cities globally, with operation and maintenance costs for impacted cities increasing on average by 53 ± 5% and replacement capital costs increasing by 44 ± 14%. We discuss why this widespread degradation might be occurring, and strategies cities have used to slow natural land cover loss.
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Rust, Ashley J., Samuel Saxe, John McCray, Charles C. Rhoades, and Terri S. Hogue. "Evaluating the factors responsible for post-fire water quality response in forests of the western USA." International Journal of Wildland Fire 28, no. 10 (2019): 769. http://dx.doi.org/10.1071/wf18191.
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Wildfires commonly increase nutrient, carbon, sediment and metal inputs to streams, yet the factors responsible for the type, magnitude and duration of water quality effects are poorly understood. Prior work by the current authors found increased nitrogen, phosphorus and cation exports were common the first 5 post-fire years from a synthesis of 159 wildfires across the western United States. In the current study, an analysis is undertaken to determine factors that best explain post-fire streamwater responses observed in those watersheds. Increased post-fire total nitrogen and phosphorus loading were proportional to the catchment extent of moderate and high burn severity. While post-fire dissolved metal concentrations were correlated with pre-fire soil organic matter. Total metal concentration increased where post-fire Normalised Difference Vegetation Index, a remote sensing indicator of live green vegetation, was low. When pre-fire soil field capacity exceeded 17%, there was a 750% median increase in total metals export to streams. Overall, the current analysis identified burn severity, post-fire vegetation cover and several soil properties as the key variables explaining extended post-fire water quality response across a broad range of conditions found in the western US.
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Taylor*, Milton D., Stephen J. Klaine, and Ted Whitwell. "Monitoring Wetland Mitigation of Nutrient Contaminants from Container Nursery Offsite Drainage." HortScience 39, no. 4 (July 2004): 856A—856. http://dx.doi.org/10.21273/hortsci.39.4.856a.
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Container-grown plants from commercial nurseries require large amounts of water and nutrients during their production cycle resulting in substantial runoff contaminated with nitrogen and phosphorus. Thus, mitigation of nutrients from exiting runoff water is a serious concern for horticultural concerns. Wight Nurseries of Monrovia Growers, Cairo, Ga., has installed 3.77 ha of planted wetlands to receive direct runoff in excess of recapture needs from a 48.6 ha drainage basin and excess water diverted from adjacent watersheds. Water flows though trench drains between wetland cells and eventually into stilling ponds before it is allowed to exit the property. Water flow through the wetlands ranges from 1.6 million to 2.2 million liters per day. Two years of monitoring data indicates strong seasonal differences in nitrate and nitrite nitrogen removal efficiencies. Nitrogen removal between April and November averaged 93.3% while removal during winter months averaged 44.1%. Nitrite was not found in wetland discharge water samples. Nitrogen as nitrate in discharge water varied from 0.05 ppm to 4.3 ppm, well below drinking water quality standards, and was below 0.6 ppm between June and November except in September during construction activity. Orthophosphate phosphorus removal was highly variable with highest removal during late spring, averaging 33.6%, and some removal during early fall, averaging 13.8%. However, there was a significant net export of phosphorus from the wetlands during winter months and during periods of low vegetative growth. Phosphorus levels ranged between 0.9 and 1.9 ppm. While there is currently no legal water quality standard, these levels are above the generally accepted level of 0.01 ppm for preventing downstream eutrophication.
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Smith, S. J., A. N. Sharpley, G. A. Coleman, and B. B. Webb. "Water Quality Impacts Associated With Peanut Culture in the Southern Plains1." Peanut Science 21, no. 1 (January 1, 1994): 60–64. http://dx.doi.org/10.3146/i0095-3679-21-1-14.
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Abstract Water quality information associated with peanut (Arachis hypogea L.) culture is limited, but needed from both environmental and agronomic standpoints. In this study, we consider surface and ground water quality characteristics involved with conventional till (viz, moldboard plow) culture of irrigated peanuts. During a 3- and a 6-year study, sediment and associated nitrogen (N) and phosphorus (P) discharge in surface water runoff were measured from two similarly managed peanut watersheds in southwestern Oklahoma. Mean annual discharge from the Cobb fine sandy loam soil (Udic Haplustalf with 2% slope) was approximately 20 Mg ha-1 sediment, 18 kg ha-1 total N, and 5 kg ha-1 total P. Annual soluble N and P losses in surface water runoff tended to be small (< 1 kg ha-1). Even so, concentrations of soluble P in runoff frequently exceeded recommended eutrophication guidelines. Successful prediction of soluble P, particulate P, and particulate N losses was achieved using appropriate kinetic desorption and enrichment ratio techniques. Concentrations of N and P in the watersheds' ground waters posed no particular water quality problems. Sampling for pesticides associated with peanut culture was made during the middle and at the end of the study, but none were detected in surface or ground waters. Overall, additional attention should be directed to reducing soil erosion. This may be done by judicious use of cover crops, and/or reduced tillage practices.
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Cho, Yongdeok. "Development of a water quality assessment model: a water quality assessment model based on watershed characteristics by non-linear regression." Water Supply 15, no. 2 (October 21, 2014): 236–47. http://dx.doi.org/10.2166/ws.2014.098.
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Here, a water quality assessment model (WQAM) is developed by non-linear regression as an alternative to physical watershed modeling in South Korea. Three cases and 10 scenarios are applied and reviewed to determine the most appropriate WQAM. The three cases are: (1) the area size allocation of sub-watersheds, (2) the watershed imperviousness ratio, and (3) the combination of the area size and imperviousness ratio. The 10 scenarios are: (1) impervious, (2) impervious + pervious, (3) impervious + rainfall, (4) impervious + slope, (5) impervious + rainfall + slope, (6) slope, (7) land usage, (8) land usage + rainfall, (9) land usage + slope, and (10) land usage + rainfall + slope. The best WQAMs are subsequently developed from the generated equations using statistics (R2, Adjusted R2, F-test, the Akaike information criterion and the Shapiro–Wilk test). In addition, the WQAM is verified using the Geum-Sum-Young River watershed. The percentage differences of biochemical oxygen demand (BOD), total nitrogen (T-N), and total phosphorus (T-P) are 31.66%, 8.08%, and 48.94%, respectively. The developed WQAM can be used in place of complex watershed modeling and to aid in the determination of the best restoration locations.
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Stephens, Scott L., Thomas Meixner, Mark Poth, Bruce McGurk, and Dale Payne. "Prescribed fire, soils, and stream water chemistry in a watershed in the Lake Tahoe Basin, California." International Journal of Wildland Fire 13, no. 1 (2004): 27. http://dx.doi.org/10.1071/wf03002.
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Before Euro-American settlement fire was a common process in the forests of the Lake Tahoe Basin. The combination of drought, fire suppression, and past harvesting has produced ecosystems that are susceptible to high-severity wildfires. Consequently, a program of prescribed fire has been recommended but there is incomplete understanding of the ecological effects of fuels treatments, especially with regard to how treatments will affect the flow of nutrients to Lake Tahoe. Nitrogen and phosphorus are the most important nutrients affecting algal growth, and thus lake clarity. Existing data demonstrate a long-term shift from a co-limitation by both nitrogen and phosphorus to phosphorus limitation. Two high-consumption, moderate-intensity prescribed fires were conducted to determine their effects on soil and stream water chemistry. Stream water calcium concentrations increased in burned watersheds whereas soluble reactive phosphorus concentrations were not significantly different. Prescribed fires released calcium and raised soil pH and this may have resulted in the incorporation of phosphorus into insoluble forms. Stream monitoring data indicates water quality effects last for ~3 months. Prescribed fires did not significantly increase the amount of soluble reactive phosphorus in stream waters. However, additional research is needed to determine if prescribed fire increases erosion or movement of particulate P, particularly in areas with steep slopes.
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Moncada, Angelica M., Assefa M. Melesse, Jagath Vithanage, and René M. Price. "Long-Term Assessment of Surface Water Quality in a Highly Managed Estuary Basin." International Journal of Environmental Research and Public Health 18, no. 17 (September 6, 2021): 9417. http://dx.doi.org/10.3390/ijerph18179417.
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Anthropogenic developments in coastal watersheds cause significant ecological changes to estuaries. Since estuaries respond to inputs on relatively long time scales, robust analyses of long-term data should be employed to account for seasonality, internal cycling, and climatological cycles. This study characterizes the water quality of a highly managed coastal basin, the St. Lucie Estuary Basin, FL, USA, from 1999 to 2019 to detect spatiotemporal differences in the estuary’s water quality and its tributaries. The estuary is artificially connected to Lake Okeechobee, so it receives fresh water from an external basin. Monthly water samples collected from November 1999 to October 2019 were assessed using principal component analysis, correlation analysis, and the Seasonal Kendall trend test. Nitrogen, phosphorus, color, total suspended solids, and turbidity concentrations varied seasonally and spatially. Inflows from Lake Okeechobee were characterized by high turbidity, while higher phosphorus concentrations characterized inflows from tributaries within the basin. Differences among tributaries within the basin may be attributed to flow regimes (e.g., significant releases vs. steady flow) and land use (e.g., pasture vs. row crops). Decreasing trends for orthophosphate, total phosphorus, and color and increasing trends for dissolved oxygen were found over the long term. Decreases in nutrient concentrations over time could be due to local mitigation efforts. Understanding the differences in water quality between the tributaries of the St. Lucie Estuary is essential for the overall water quality management of the estuary.
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Aron, Joan L., Robert K. Hall, Michael J. Philbin, and Robin J. Schafer. "Using watershed function as the leading indicator for water quality." Water Policy 15, no. 5 (July 10, 2013): 850–58. http://dx.doi.org/10.2166/wp.2013.111.
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Diffuse nonpoint source (NPS) pollutants, such as sediment, nitrogen, phosphorus, and pathogens, have become the primary cause of water quality impairments in the United States of America. Resource management agencies in the USA are expanding the use of tools for the assessment of ecosystem function in water quality programs to control NPS pollution to meet US Clean Water Act objectives. Assessing the ecosystem function of upland and riparian areas provides the context for monitoring data that can improve the targeting of best management practices for NPS pollution, and be a leading (early) indicator for more timely decisions about aquatic habitat and water quality. Assessment of watershed function can be applied to prioritizing resources, developing indicators, monitoring aquatic habitat and water quality, and implementing adaptive management plans to restore degraded ecosystems that are producing NPS pollution. This paper presents three examples of progress in the institutionalization of this approach to water quality programs for sustainable and healthy watersheds that affect federal, state, tribal, and private landowners. Future work should refine the approach by evaluating the benefits, costs, and effectiveness of the use of watershed function in water quality programs.
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Prepas, E. E., D. Planas, J. J. Gibson, D. H. Vitt, T. D. Prowse, W. P. Dinsmore, L. A. Halsey, et al. "Landscape variables influencing nutrients and phytoplankton communities in Boreal Plain lakes of northern Alberta: a comparison of wetland- and upland-dominated catchments." Canadian Journal of Fisheries and Aquatic Sciences 58, no. 7 (July 1, 2001): 1286–99. http://dx.doi.org/10.1139/f01-081.
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A review of headwater lakes in undisturbed watersheds on the Boreal Plain, with indirect gradient analyses of chemical data, indicated a clear separation between those in wetland-dominated watersheds (57100% wetland with variable proportions of bog, fen, swamp, and marsh cover) and those in upland-dominated watersheds (044% wetland cover). In the former, percentage wetland cover in the watershed was positively correlated with total phosphorus (TP, r2 = 0.78, primarily bog), total nitrogen (TN, r2 = 0.50), and dissolved organic carbon (DOC, r2 = 0.74) concentrations. Rich fens appeared to sequester both TP and TN. In upland-dominated lakes, the ratio of catchment area to lake volume (CA/LV) was the strongest watershed correlate of TP concentration (r2 = 0.56), whereas most limnetic nitrogen and DOC were generated in situ. Colour concentration, being highest in wetland lakes, was correlated with the ratio of isotopically defined effective drainage basin area to lake volume (eDBA/LV, r2 = 0.63). Drainage basin slope was only weakly associated with water quality, likely because of low topographic relief ([Formula: see text]11%). Higher Chlorophyta and Peridineae biomasses in wetland-dominated systems than in upland-dominated ones may coincide with greater NH4+ availability.
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Stillwell, Charles C., William F. Hunt, Jonathan L. Page, Joshua B. Baird, and Shawn G. Kennedy. "Stormwater management in nutrient-sensitive watersheds: a case study investigating impervious cover limits and pollutant-load regulations." Water Science and Technology 78, no. 3 (July 25, 2018): 664–75. http://dx.doi.org/10.2166/wst.2018.338.
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Abstract The objective of this research project was to compare two stormwater management strategies within a nutrient-sensitive watershed: impervious cover limits versus pollutant-load regulations. A case study was conducted in the nutrient-sensitive Falls Lake watershed in North Carolina, USA, where a commercial fitness complex was constructed in a zone previously restricted to low-density housing. The Falls Lake watershed has a stormwater regulation that limits total nitrogen and total phosphorus export loads to 2.47 kg/ha/yr and 0.37 kg/ha/yr, respectively. Hydrology and water quality were monitored pre- and post-development to quantify changes to stormwater volumes, pollutant concentrations, and annual export loading rates. On-site stormwater control measures (SCMs) reduced nutrient export loading rates below the regulatory standard. However, increased stormwater volumes and nutrient export loading rates were observed from pervious surfaces that were disturbed during construction (total nitrogen increased from 2.06 to 4.24 kg/ha/yr, total phosphorus increased from 0.41 to 0.73 kg/ha/yr). Results from this case study suggest that (1) impervious cover limits do not adequately account for a parcel's nutrient export loads and (2) SCMs that reduce volume and treat pollutants can reduce nutrient export loads below regulatory levels in the Falls Lake watershed.
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Zeng, W. J., J. H. Li, J. X. Wang, Y. Wang, L. Bao, L. J. Liao, X. F. Guo, Y. X. Guo, B. L. Wu, and J. S. Zhang. "Research on response of water quality to land use pattern in nine plateau lake watersheds of Yunnan Province, China." Water Supply 20, no. 8 (July 24, 2020): 3739–51. http://dx.doi.org/10.2166/ws.2020.139.
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Abstract To study how water quality responds to land use types is of great significance in realizing effective control of non-point source pollution. This study built a response model of water quality to land use. The research results are as follows. First, the proportion of farmland is positively correlated to the total phosphorus (TP) value and biochemical oxygen demand (BOD) value, which indicates that the water quality deteriorates as the area of farmland increases. Second, the proportion of woodland is negatively correlated to the permanganate index, the trophic state index, total nitrogen (TN) value, TP value and BOD value, which means the water quality improves as the area of woodland increases. Third, the proportion of grassland is negatively correlated to the water quality indices and the correlation coefficient is large, which indicates that the water quality improves as the area of grassland increases. Fourth, the proportion of land used for buildings is positively correlated to the trophic state index and the chemical oxygen demand (COD) value at the 0.05 significance level, which means that the water quality deteriorates as the area of land for buildings increases. This study is expected to provide a basis for optimization of the land use and effective pollution control in the nine plateau lake watersheds.
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Perera, E. D. P., Y. Iwami, and K. Fukami. "Point and non-point source nutrient loading simulation for the Takasaki River Basin, Chiba–Japan." Water Practice and Technology 10, no. 2 (June 1, 2015): 328–36. http://dx.doi.org/10.2166/wpt.2015.039.
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Urbanization, agriculture, fertilization, livestock farming and unprecedented precipitations are presumed to cause augmented loadings of nitrogen (N) and phosphorus (P) to rivers and downstream reservoirs. At present, point source (PS) pollution in watersheds can easily be controlled, and it has been well-managed due to growing awareness and strict low enforcements. However, the control of pollutants from non-point sources (NPS) is still challenging and NPS have been identified as the main cause of water pollution and eutrophication in watersheds at present. Limitations in technical, human and financial resources impede efficient monitoring of those influents at watershed scale. At this end, process-based modelling approaches play an important role in analysis of nutrient loading effects quantitatively and qualitatively. Process-based water and energy processes (WEP) hydrological model with its updated version to couple nutrient loading through the implementation of N and P circulation processes was studied in this paper highlighting the application of the model to the Takasaki River, a tributary to the Inba-numa Lake basin, Chiba prefecture, Japan to understand the impacts of PS and NPS to the river water quality.
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lital, Arvo, Enn Loigu, and Nils Vagstad. "Nutrient Losses and N & P Balances in Small Agricultural Watersheds in Estonia." Hydrology Research 34, no. 5 (October 1, 2003): 531–42. http://dx.doi.org/10.2166/nh.2003.0023.
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The paper deals with nutrient runoff monitoring results and calculated nutrient budgets on catchment level in small agricultural watersheds in Estonia. A special programme for monitoring of nutrient losses was initiated and a network of monitoring stations, equipped with data-loggers and suitable devices for continuous flow measurement and flow-proportional automatic water sampling were established in Estonia in the mid-1990s. The research methodology is harmonized with the Nordic countries as well as with the other Baltic countries. The results indicate that nutrients losses are relatively low (generally below 11 kg N/ha and 0.9 kg P/ha). It can be partly explained by drastic changes in the Estonian agricultural practice in the 1990s but also by differences in runoff regime. Nutrient balances were calculated for two catchments, based on the data collected from the farms, some special studies and water quality monitoring results in two watersheds in 1995 (1999) - 2001. The nutrient balances for the catchments turned positive after being negative both for nitrogen and phosphorus in the mid-1990s.
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Patoine, M., S. Hébert, and F. D'Auteuil-Potvin. "Water quality trends in the last decade for ten watersheds dominated by diffuse pollution in Québec (Canada)." Water Science and Technology 65, no. 6 (March 1, 2012): 1095–101. http://dx.doi.org/10.2166/wst.2012.850.
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The aim of this work is to evaluate and discuss river water quality trends over the last decade in ten watersheds where diffuse pollution represents more than half of the annual load of phosphorus (P) and nitrogen (N). Trend analyses taking into account flow data indicate a significant reduction of total P in eight rivers, of ammonia N in five rivers, of nitrate + nitrite in four rivers, of total filtered N in three rivers and of suspended solids in two rivers. An increase of turbidity was observed in four rivers and, for fecal coliforms, no trends. P decrease can be explained by reduced mineral P inputs on cropped lands related to means such as agro-environmental fertilization plans and addition of phytase in pig and poultry feed. However, for seven of them, median P concentrations remain at least two times greater than the Québec water quality guideline for protection of rivers against eutrophication. Concentrations of other parameters remain problematic in some rivers too. These results indicate the need to continue the efforts for further diffuse pollution reduction. Future work should better quantify actions taken at the watershed scale to reduce diffuse pollution.
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Gao, Lin, Junyu Qi, Sheng Li, Glenn Benoy, Zisheng Xing, and Fan-Rui Meng. "Effects of sampling frequency on estimation accuracies of annual loadings for water quality parameters in different sized watersheds." Water Quality Research Journal 55, no. 3 (April 2, 2020): 261–77. http://dx.doi.org/10.2166/wqrj.2020.012.
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Abstract Potential errors or uncertainties of annual loading estimations for water quality parameters such as suspended solids (SS), nitrate-nitrogen (NO3-N), ortho-phosphorus (Ortho-P), potassium (K), calcium (Ca), and magnesium (Mg) can be greatly affected by sampling frequencies. In this study, annual loading estimation errors were assessed in terms of the coefficient of variation, relative bias, and probability of potential errors that were estimated with statistical samples taken at a series of sampling frequencies for a watershed in northwestern New Brunswick, Canada, and one of its sub-watersheds. Results indicate that annual loading estimation errors increased with decreasing sampling frequency for all water quality parameters. At the same sampling frequencies, the estimation errors were several times greater for the smaller watershed than those for the larger watershed, possibly due to the flushing nature of streamflows in the smaller watershed. We also found that low sampling frequency tended to underestimate the annual loadings of water quality parameters dominated by stormflow events (SS and K) and overestimate water quality parameters dominated by baseflow (Mg and Ca). These results can be used by hydrologists and water quality managers to determine sampling frequencies that minimize costs while providing acceptable estimation errors. This study also demonstrates a novel approach to assess potential errors when analyzing existing water quality data.
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Bian, Ziqi, Lyuyi Liu, and Shengyan Ding. "Correlation between Spatial-Temporal Variation in Landscape Patterns and Surface Water Quality: A Case Study in the Yi River Watershed, China." Applied Sciences 9, no. 6 (March 13, 2019): 1053. http://dx.doi.org/10.3390/app9061053.
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The evidence for a correlation between landscape patterns and surface water quality is still weak. We chose the Yi River watershed in China as a study area. We selected and determined the chemical oxygen demand, ammonia nitrogen, total phosphorus, dissolved oxygen, and electric conductivity to represent the surface water quality. We analyzed the spatial distribution of the surface water quality. Buffer zones with five different radii were built around each sampling site to analyze landscape patterns on different scales. A correlation analysis was completed to examine the influencing rules and the response mechanisms between landscape patterns and surface water quality indicators. The results show that: (1) Different landscape composition types impact the surface water quality differently and increasing the area of forest land can effectively reduce non-point source pollution, (2) an increase in urban area may threaten the surface water quality, and (3) landscape compositional change has a greater influence on surface water quality compared to landscape configurational change. This study provides a scientific foundation for the spatial development of watersheds and outlines a strategy for improving the sustainability of surface water quality and the surrounding environment.
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Ma, Xiao, Ye Li, Shuang Du, and Fang Zhao Zheng. "Spatial Analysis of Nitrogen and Phosphorus Loads from Non-Point Source in the Three Gorges Reservoir Area of Hubei." Applied Mechanics and Materials 71-78 (July 2011): 3062–66. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.3062.
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Recently, increasing nutrient (i.e., nitrogen and phosphorus) concentrations have been observed in the surface water of many countries and the non-point source (NPS) pollution has become an important factor in the deterioration of water quality in the Three Gorges Reservoir Area (TGRA). The spatial and temporal analysis of NPS pollution loads in the TGRA of Hubei from 2005 to 2009 were estimated using export coefficient model in this paper. The results indicated the nutrient from rainfall was the dominant NPS of both TN and TP pollution. The spatial analysis of N and P loads from NPS in the TGRA of Hubei showed that the nutrient loads in BD County and YL District were higher than the other two counties in the study area. These findings demonstrate that the model could provide a simple and reliable approach to evaluate N and P loads to TGRA of Hubei and may be useful for planning and management of the local agricultural watersheds
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Line, Dan E., Deanna L. Osmond, and Wesley Childres. "Nutrient Export from Agricultural Watersheds in the Piedmont and Coastal Plain, North Carolina." Transactions of the ASABE 62, no. 5 (2019): 1135–45. http://dx.doi.org/10.13031/trans.13052.
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Abstract. Nitrogen (N) and phosphorus (P) input and export rates were determined in six rural, predominantly agricultural watersheds located in the Piedmont and Coastal Plain regions of North Carolina. Water quality monitoring was conducted at the outlets for 2.3 to 8.0 years to determine the annual N and P export from each watershed. Total N and P input and export from five of the six watersheds were correlated, with only a no-till cropland watershed differing. The correlation showed that N and P exports increased by about 4.0% and 8.7%, respectively, of applied N and P for the range of applications rates, whereas dissolved N (NOx-N) export increased by 2.8% with increasing N application rates. Therefore, practices that reduce inputs, such as nutrient management, should result in similar percentage reductions in exports. The Small Watershed Nutrient Forecasting Tool (SWIFT) was used to forecast discharge, N, P, and sediment export from each of the six watersheds. For the no-till cropland watershed, the SWIFT-forecasted N and P export rates were more than 2.5 times those measured, while the sediment export rate was 72 times the measured value. Thus, these data showed that the SWIFT forecasts for N, P, and sediment export were poor for the no-till cropland watershed. For the pasture watershed, the SWIFT forecasts for N and sediment export agreed reasonably well with measured export; however, the forecasted P export was much less than measured. For the four mixed land use watersheds, the SWIFT forecasts for discharge, TN, and sediment were mostly greater than measured, and the forecasted TP export was less than measured for three of the four watersheds. Thus, as with many predicstion tools, SWIFT results must be used with caution. Keywords: Nutrient export, Nutrient management practice, Water quality monitoring.
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Ahn, So Ra, and Seong Joon Kim. "Assessment of integrated watershed health based on the natural environment, hydrology, water quality, and aquatic ecology." Hydrology and Earth System Sciences 21, no. 11 (November 14, 2017): 5583–602. http://dx.doi.org/10.5194/hess-21-5583-2017.
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Abstract. Watershed health, including the natural environment, hydrology, water quality, and aquatic ecology, is assessed for the Han River basin (34 148 km2) in South Korea by using the Soil and Water Assessment Tool (SWAT). The evaluation procedures follow those of the Healthy Watersheds Assessment by the U.S. Environmental Protection Agency (EPA). Six components of the watershed landscape are examined to evaluate the watershed health (basin natural capacity): stream geomorphology, hydrology, water quality, aquatic habitat condition, and biological condition. In particular, the SWAT is applied to the study basin for the hydrology and water-quality components, including 237 sub-watersheds (within a standard watershed on the Korea Hydrologic Unit Map) along with three multipurpose dams, one hydroelectric dam, and three multifunction weirs. The SWAT is calibrated (2005–2009) and validated (2010–2014) by using each dam and weir operation, the flux-tower evapotranspiration, the time-domain reflectometry (TDR) soil moisture, and groundwater-level data for the hydrology assessment, and by using sediment, total phosphorus, and total nitrogen data for the water-quality assessment. The water balance, which considers the surface–groundwater interactions and variations in the stream-water quality, is quantified according to the sub-watershed-scale relationship between the watershed hydrologic cycle and stream-water quality. We assess the integrated watershed health according to the U.S. EPA evaluation process based on the vulnerability levels of the natural environment, water resources, water quality, and ecosystem components. The results indicate that the watershed's health declined during the most recent 10-year period of 2005–2014, as indicated by the worse results for the surface process metric and soil water dynamics compared to those of the 1995–2004 period. The integrated watershed health tended to decrease farther downstream within the watershed.
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Qi, Junyu, Sheng Li, Charles P. A. Bourque, Zisheng Xing, and Fan-Rui Meng. "Developing a decision support tool for assessing land use change and BMPs in ungauged watersheds based on decision rules provided by SWAT simulation." Hydrology and Earth System Sciences 22, no. 7 (July 18, 2018): 3789–806. http://dx.doi.org/10.5194/hess-22-3789-2018.
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Abstract. Decision making on water resources management at ungauged, especially large-scale watersheds relies on hydrological modeling. Physically based distributed hydrological models require complicated setup, calibration, and validation processes, which may delay their acceptance among decision makers. This study presents an approach to develop a simple decision support tool (DST) for decision makers and economists to evaluate multiyear impacts of land use change and best management practices (BMPs) on water quantity and quality for ungauged watersheds. The example DST developed in the present study was based on statistical equations derived from Soil and Water Assessment Tool (SWAT) simulations and applied to a small experimental watershed in northwest New Brunswick. The DST was subsequently tested against field measurements and SWAT simulations for a larger watershed. Results from DST could reproduce both field data and model simulations of annual stream discharge and sediment and nutrient loadings. The relative error of mean annual discharge and sediment, nitrate–nitrogen, and soluble-phosphorus loadings were −6, −52, 27, and −16 %, respectively, for long-term simulation. Compared with SWAT, DST has fewer input requirements and can be applied to multiple watersheds without additional calibration. Also, scenario analyses with DST can be directly conducted for different combinations of land use and BMPs without complex model setup procedures. The approach in developing DST can be applied to other regions of the world because of its flexible structure.
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Duan, S., and S. S. Kaushal. "Salinization alters fluxes of bioreactive elements from stream ecosystems across land use." Biogeosciences 12, no. 23 (December 15, 2015): 7331–47. http://dx.doi.org/10.5194/bg-12-7331-2015.
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Abstract. There has been increased salinization of fresh water over decades due to the use of road salt deicers, wastewater discharges, saltwater intrusion, human-accelerated weathering, and groundwater irrigation. Salinization can mobilize bioreactive elements (carbon, nitrogen, phosphorus, sulfur) chemically via ion exchange and/or biologically via influencing of microbial activity. However, the effects of salinization on coupled biogeochemical cycles are still not well understood. We investigated potential impacts of increased salinization on fluxes of bioreactive elements from stream ecosystems (sediments and riparian soils) to overlying stream water and evaluated the implications of percent urban land use on salinization effects. Two-day incubations of sediments and soils with stream and deionized water across three salt levels were conducted at eight routine monitoring stations across a land-use gradient at the Baltimore Ecosystem Study Long-Term Ecological Research (LTER) site in the Chesapeake Bay watershed. Results indicated (1) salinization typically increased sediment releases of labile dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), total dissolved Kjeldahl nitrogen (TKN) (ammonium + ammonia + dissolved organic nitrogen), and sediment transformations of nitrate; (2) salinization generally decreased DOC aromaticity and fluxes of soluble reactive phosphorus from both sediments and soils; (3) the effects of increased salinization on sediment releases of DOC and TKN and DOC quality increased with percentage watershed urbanization. Biogeochemical responses to salinization varied between sediments and riparian soils in releases of DOC and DIC, and nitrate transformations. The differential responses of riparian soils and sediments to increased salinization were likely due to differences in organic matter sources and composition. Our results suggest that short-term increases in salinization can cause releases of significant amounts of labile organic carbon and nitrogen from stream substrates and organic transformations of nitrogen and phosphorus in urban watersheds. Given that salinization of fresh water will increase in the future due to human activities, significant impacts on carbon and nutrient mobilization and water quality should be anticipated.
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Amano, Koji, and Takehiko Fukushima. "On the Longitudinal and Vertical Changes in Lake Estuarine Sediments." Water Science and Technology 20, no. 6-7 (June 1, 1988): 143–53. http://dx.doi.org/10.2166/wst.1988.0198.
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In order to obtain environmental information about lake water and watersheds, the vertical and longitudinal distributions of physical and chemical properties in lake sediments were investigated. The concentrations of several substances (e.g., nutrients, metals, and chemicals) in the sediments were determined at fifty sampling sites in sixteen shallow lakes in Japan. The vertical profiles of particle size, particle organic carbon, particle organic nitrogen, total phosphorus, some metals (Ti, Mn, Fe, Zn, and Cu), and LAS were analysed. Various sediment properties, such as the sedimentation conditions and the redox conditions, were related to the vertical profiles observed, and traces of historical changes in the water and watersheds were found in the sediments. Longitudinal changes in the sediments between the mouths of the rivers and the deepest points of the lakes were clearly observed, and it was expected that these changes would correlate with one of the estuarine characteristics since they reflect the spatial variation in average composition of the particulate matter and in the average water quality. Some significant relationships between the lake sediments and the lake or watershed type were observed, indicating the possibility that lake sediments may be one of the most important indices for understanding lake environments.
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Erkossa, T., A. Wudneh, B. Desalegn, and G. Taye. "Linking soil erosion to onsite financial cost: lessons from watersheds in the Blue Nile basin." Solid Earth Discussions 7, no. 1 (February 4, 2015): 565–94. http://dx.doi.org/10.5194/sed-7-565-2015.
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Abstract. The study was conducted in three watersheds (Dapo, Meja and Mizewa) in the Ethiopian part of the Blue Nile Basin to estimate the onsite cost of soil erosion using the productivity change approach, in which crop yield reduction due to plant nutrients lost with the sediment and runoff has been analyzed. For this purpose, runoff measurement and sampling was conducted during the main rainy season of 2011 at the outlet of two to three sub watersheds in each watershed. The sediment concentration of the runoff, and nitrogen and phosphorus content of the runoff and sediment were determined. Crop response functions were developed for the two plant nutrients based on data obtained from the nearest Agricultural Research Centers. The response functions were used to estimate crop yield reduction as a result of the lost N and P assuming there is no compensation through fertilization. The results show a significant yield reduction and resultant financial loss to the farmers. Considering only grain yield of maize (Zea mays), farmers at Dapo annually lose about 220 and USD 150 ha-1 due to the loss of nitrogen and phosphorus, respectively. In view of the importance of the crop residues including as feed, the loss can be even greater. The study demonstrated that in addition to the long-term deterioration of land quality, the annual financial loss suffered by farmers is substantial. Therefore, on farm soil and water conservation measures that are suitable in biophysical and socio-economic terms in the landscapes and beyond need to be encouraged.
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Lea-Cox, John D., David S. Ross, and K. Marc Teffeau. "A Water and Nutrient Management Planning Process for Container Nursery and Greenhouse Production Systems in Maryland." Journal of Environmental Horticulture 19, no. 4 (December 1, 2001): 230–36. http://dx.doi.org/10.24266/0738-2898-19.4.230.
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Abstract Many states throughout the United States are now concerned about the impact of non-point source pollution on the declining quality of water in their watersheds. In 1998, the state of Maryland adopted one of the toughest nutrient management planning laws in the nation, requiring virtually all agricultural operations to write and implement nitrogen (N) and phosphorus (P) based management plans by December 31, 2002. The nursery and greenhouse industries are faced with a complicated task to write these nutrient management plans, since these operations grow a large number of plant species utilizing a range of fertilization and irrigation strategies. A nutrient management planning strategy has been identified that will provide an assessment of nutrient loss potential from a wide variety of production scenarios, identify the specific factors that contribute most to nutrient leaching and runoff, and enable targeted best management practices to be implemented to reduce the risk of nutrient run-off.
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Cho, Yongdeok. "A watershed water quality evaluation model using data mining as an alternative to physical watershed models." Water Supply 16, no. 3 (December 23, 2015): 703–14. http://dx.doi.org/10.2166/ws.2015.180.
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This paper presents a data mining (DM)-based approach to developing a watershed water quality evaluation model (water quality evaluation model based on data mining (WQEMD)) as an alternative to physical watershed models. Three DM techniques (i.e. model tree, artificial neural network, and radial basis function) were employed to develop a WQEMD based on watershed characteristics (e.g. hydrology, geology, and land usage). To represent watershed characteristics, three cases and ten scenarios were considered. The three cases were defined as (1) the size (area) allocation of sub-watersheds, (2) the watershed imperviousness ratio, and (3) the combination of the area and imperviousness ratio. The ten scenarios were composed of the following parameters; impervious, pervious, land usage, rainfall, slope. The best WQEMDs were subsequently developed using statistics (correlation coefficient, mean-absolute error, root mean-squared error, and root relative-squared error). In addition, the WQEMDs developed were then verified using the Geum-Sum-Youngsan River watershed. The percentage difference of biochemical oxygen demand (BOD), total nitrogen (T-N) and total phosphorus (T-P) were 30.6%, 23.44%, and 2.79%, respectively. The results show that a WQEMD developed in this way is effective and can be used in place of a physical watershed model and is useful to aid in determining areas having the best potential for successful remediation.
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Park, Minji, Young Soon Choi, Hyung Jin Shin, Inhong Song, Chun Gyeong Yoon, Joong Dae Choi, and Soon Ju Yu. "A Comparison Study of Runoff Characteristics of Non-Point Source Pollution from Three Watersheds in South Korea." Water 11, no. 5 (May 8, 2019): 966. http://dx.doi.org/10.3390/w11050966.
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Three watersheds in Korea (Dochoncheon, Gongjicheon, Seolseongcheon) with different land cover characteristics were selected for non-point source pollution monitoring. Event mean concentration (EMC) was calculated, and runoff characteristics were compared through first-flushing and statistical analyses. The mean of the water quality parameters was the highest in Seolseongcheon during dry days among the three watersheds. EMCs of biochemical oxygen demand (BOD) and total nitrogen (TN) were higher in Dochoncheon and Gongjicheon during rainy days, respectively. The upper Seolseongchun watershed showed overall greater values of chemical oxygen demand (COD), suspended solids (SS), total organic carbon (TOC), and total phosphorus (TP). First-flush analyses indicated that SS had the strongest and TN had the weakest effects on the first flush. BOD was the highest in Dochoncheon (urban watershed) and increased with increased number of antecedent dry days. Rainfall intensity appeared to affect SS runoff strongly in Gongjicheon and Seolseongcheon. COD showed strong correlation with SS and TOC in all watersheds, and organic matter (COD and TOC) demonstrated high factor loads during dry and rainy days. Thus, organic matter–related factors were classified as the major factors in pollutant loads. TP and TN were separately classified during dry days in Gongjicheon and Seolseongcheon, whereas these were the secondary factors during rainfall when the influence of non-point pollution was substantial. Cluster analyses showed that the monitoring sites in Dochoncheon and Gongjicheon watersheds were closer than Seolseongcheon. As a result of the comparison of non-point source pollution runoff in the three watersheds, it was difficult to explain the non-point source pollution runoff by specific characteristics such as land cover. For science-based management of non-point pollution, it is necessary to obtain additional survey data considering the climatic, geographical and major industries.
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Xin, Zhuohang, Lei Ye, and Chi Zhang. "Application of Export Coefficient Model and QUAL2K for Water Environmental Management in a Rural Watershed." Sustainability 11, no. 21 (October 30, 2019): 6022. http://dx.doi.org/10.3390/su11216022.
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Water quality deterioration caused by excessive nutrient discharge from various point and non-point sources are a global challenge. Understanding the pollution sources and their respective contribution is the prerequisite for environmental planning, management and restoration. In this study, the influence of complex pollution sources on the water quality of the Dengsha River watershed in Dalian, China, was investigated. The export coefficient method was coupled with the QUAL2K water quality model to estimate the loads of ammonia nitrogen (NH4-N) and total phosphorus (TP) from different sources, and to explore their respective contributions. Results indicated that animal feedlot and crop production were major sources for NH4-N load, and crop production, soil erosion and animal feedlot are the largest three sources of TP load with an annual total contribution of 98.4%. The pollutant load exhibited an intra-annual variation mainly due to the seasonality of rainfall and anthropogenic agricultural activities. The overall waste assimilation capacity (WAC) is overloaded and suggestions for water pollution control and treatment regarding each pollution source were proposed. This study addressed a new application of QUAL2K model coupled with the export coefficient model for watershed managers towards a sustainable water environmental management, and can therefore be a reference example for other small and medium-sized rural watersheds.
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Rust, Ashley J., Terri S. Hogue, Samuel Saxe, and John McCray. "Post-fire water-quality response in the western United States." International Journal of Wildland Fire 27, no. 3 (2018): 203. http://dx.doi.org/10.1071/wf17115.
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Wildfires are increasing in size and severity in forested landscapes across the Western United States. Not only do fires alter land surfaces, but they also affect the surface water quality in downstream systems. Previous studies of individual fires have observed an increase in various forms of nutrients, ions, sediments and metals in stream water for different post-fire time periods. In this research, data were compiled for over 24 000 fires across the western United States to evaluate post-fire water-quality response. The database included millions of water-quality data points downstream of these fires, and was synthesised along with geophysical data from each burned watershed. Data from 159 fires in 153 burned watersheds were used to identify common water-quality response during the first 5 years after a fire. Within this large dataset, a subset of seven fires was examined further to identify trends in water-quality response. Change-point analysis was used to identify moments in the post-fire water-quality data where significant shifts in analyte concentrations occurred. Evaluating individual fires revealed strong initial increases or decreases in concentrations, depending on the analyte, that are masked when averaged over 5 years. Evidence from this analysis shows significant increases in nutrient flux (different forms of nitrogen and phosphorus), major-ion flux and metal concentrations are the most common changes in stream water quality within the first 5 years after fire. Dissolved constituents of ions and metals tended to decrease in concentration 5 years after fire whereas particulate matter concentration continued to increase. Assembling this unique and extensive dataset provided the opportunity to determine the most common post-fire water-quality changes in the large and diverse Western USA. Results from this study could inform studies in other parts of the world, will help parameterise and validate post-fire water-quality models, and assist communities affected by wildfire to anticipate changes to their water quality.
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Almeida, Carina, Tiago Ramos, Pedro Segurado, Paulo Branco, Ramiro Neves, and Rodrigo Proença de Oliveira. "Water Quantity and Quality under Future Climate and Societal Scenarios: A Basin-Wide Approach Applied to the Sorraia River, Portugal." Water 10, no. 9 (September 4, 2018): 1186. http://dx.doi.org/10.3390/w10091186.
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Water resources are impacted by several stressors like over-population and over consumption that compromises their availability. These stressors are expected to progressively intensify due to climate change in most regions of the world, with direct impact on watersheds and river systems. This study investigates the effect of different watershed pressure scenarios due to climate change in the hydrological regime of the Sorraia River basin, Portugal. This catchment includes one of the largest irrigated areas in the country, thus being strongly influenced by anthropogenic activities, associated to hydrological (irrigation, flow regulation, damming) and nutrient stressors. The Soil Water Assessment Tool has been used to simulate water flow and nutrient dynamics in the watershed while considering inputs from two climate models and three societal scenarios. Results have shown that the predicted rainfall reductions will have a significant impact on river flow and nutrient concentrations when compared to baseline conditions. River flow will expectably decrease by 75%, while nitrogen and phosphorus concentrations in river water will expectably increase by 500% and 200%, respectively. These differences are more evident for storylines that consider increasing pressures such as population growth and agricultural expansion marked with unsustainable practices and increased reliance on technology. The results of this study indicate a possible future outcome and provide effective guidelines for the formulation of water management policies to counter the impacts of climate change and corresponding environmental pressures in the Sorraia River basin.
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Kim, Ji, Usman Atique, and Kwang-Guk An. "Relative Abundance and Invasion Dynamics of Alien Fish Species Linked to Chemical Conditions, Ecosystem Health, Native Fish Assemblage, and Stream Order." Water 13, no. 2 (January 12, 2021): 158. http://dx.doi.org/10.3390/w13020158.
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The incidence and dispersal of invasive alien fish species (IAFS) have ecological impacts on biodiversity and environmental health at regional to global scales. We identified links between the presence of largemouth bass (Lb) and bluegill (Bg), and selected indicators of environmental water quality, trophic and tolerance guilds, ecological health factors, and stream order. We used the data collected from national biomonitoring study sites in four major rivers of South Korea. IAFS occurred in eutrophic waters (Lb = total phosphorus: 140 ± 170 µg/L, chlorophyll a: 16.7 ± 27.5 µg/L; Bg = total phosphorus: 160 ± 190 µg/L, chlorophyll a: 19.43 ± 28.05 µg/L) and dominated at higher ambient ratios of total nitrogen to total phosphorus (TN:TP). At TN:TP ≤ 100, the relative abundance of Lb and Bg was highest (95.3% and 96.0%, respectively). Concerning tolerance guilds, Lb (R2 = 0.78, p < 0.0001) and Bg (R2 = 0.59, p < 0.0001) had positive relationships with tolerant species in all four river watersheds and negative relationships with the percentages of insectivores and omnivores. This indicates the harmful impacts of IAFS on the aquatic food web. These invasive fish species also influenced stream health, particularly in the Nakdong and Yeongsan/Seomjin rivers. Our findings suggest that assessing chemical water quality can help identify the optimal and suboptimal survival and spread ranges of IAFS (Lb and Bg), as they directly influence tolerance and trophic guilds in the aquatic food web. In conclusion, these IAFS could be a major factor in the deteriorating ecosystem health, which had negative relationships with the abundance and occurrence of IAFS. Therefore, approaches that use appropriate water chemistry factors and species tolerance may provide critical insights into the efficient management of river health that has been perturbed by the presence of IAFS.
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DeMoranville, Carolyn. "Cranberry Nutrient Management in Southeastern Massachusetts: Balancing Crop Production Needs and Water Quality." HortTechnology 25, no. 4 (August 2015): 471–76. http://dx.doi.org/10.21273/horttech.25.4.471.
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The american cranberry (Vaccinium macrocarpon) is a wetland plant native to North America. The plant is adapted to sandy, nutrient-poor, low pH soils and thus, like blueberry (Vaccinium sp.), its nutritional requirements are low compared with many other perennial fruit crops. Research conducted over the past 30 years has defined the annual requirements for nitrogen [N (20–60 lb/acre)], phosphorus [P (<20 lb/acre)], and potassium (40–120 lb/acre) based on tissue testing, plant growth demands, potential for remobilization, and determination of removal in the crop. These three nutrient elements are those most commonly applied to the crop in fertilizers. However, much of the work on nutrient rate requirements was conducted on native cultivars and there is an expectation that requirements of newer hybrid cultivars are greater. In Massachusetts, cranberries are grown in coastal watersheds and often depend on small lakes as their water source for irrigation, harvest, and winter flooding. Since cranberry production is heavily dependent on water use, the interaction of nutrient management and water management has become a primary focus area for research and extension, particularly for N and P, the nutrient elements most frequently associated with environmental pollution. Recent preliminary research examining cranberry farms with varied configurations (e.g., water passes through the bog and exits via a long channel, water recirculates back into the supply water body) has indicated that the cranberry bogs may act as either a source or sink for N depending on configuration and management activities. In a study of cranberry farms where P use was reduced to an average of <10 lb/acre, P concentration in harvest flood water declined by as much as 85% while crop production was sustained. Site variation in output of N and P in cranberry drainage and flood waters indicates the need for further research into the variables that control these processes, including soil types, site hydrology, nutrient application rates and forms, and water-management activities.
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Gorgoglione, Angela, Andrea Gioia, and Vito Iacobellis. "A Framework for Assessing Modeling Performance and Effects of Rainfall-Catchment-Drainage Characteristics on Nutrient Urban Runoff in Poorly Gauged Watersheds." Sustainability 11, no. 18 (September 10, 2019): 4933. http://dx.doi.org/10.3390/su11184933.
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Protection of surface water quality plays a crucial role for sustainable urban watershed management since the wash-off from impervious contaminated surfaces generates transport phenomena from a range of pollutants (like nutrients, such as total nitrogen (Ntot) and total phosphorus (Ptot)). This leads to the consequent reduction of water quality, and to phenomena, such as eutrophication and the presence of algae blooms. For this reason, a comprehensive understanding of nutrient build-up and wash-off is essential for efficient stormwater treatment design. However, data scarcity could represent one of the main limitations in this context. This manuscript presents a methodological framework able to tackle such limitations by an in-depth investigation of the main factors that influence the build-up and wash-off from impervious surfaces, including rainfall, watershed, and drainage-network characteristics. The outcomes highlight the key role played by the antecedent dry period, among the rainfall characteristics, and the width of the overland flow path, among the catchment/drainage characteristics. It is also confirmed as appropriate to use suspended solids as a surrogate for the investigation of the behavior of other pollutant species. Additionally, the capability of this approach in assessing modeling performance was successfully tested. The results of the present study are expected to contribute valuable knowledge for defining effective management strategies to minimize stream pollution and protect the health of aquatic ecosystems in urban watersheds characterized by data scarcity.
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Jordan, Thomas E., Donald E. Weller, and Carey E. Pelc. "Effects of Local Watershed Land Use on Water Quality in Mid-Atlantic Coastal Bays and Subestuaries of the Chesapeake Bay." Estuaries and Coasts 41, S1 (August 23, 2017): 38–53. http://dx.doi.org/10.1007/s12237-017-0303-5.
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Abstract Nutrient inputs have degraded estuaries worldwide. We investigated the sources and effects of nutrient inputs by comparing water quality at shallow (< 2m deep) nearshore (within 200 m) locations in a total of 49 Chesapeake subestuaries and Mid-Atlantic coastal bays with differing local watershed land use. During July–October, concentrations of total nitrogen (TN), dissolved ammonium, dissolved inorganic N (DIN), and chlorophyll a were positively correlated with the percentages of cropland and developed land in the local watersheds. TN, DIN, and nitrate were positively correlated with the ratio of watershed area to subestuary area. Total phosphorus (TP) and dissolved phosphate increased with cropland but were not affected by developed land. The relationships among N, P, chlorophyll a, and land use suggest N limitation of chlorophyll a production from July–October. We compared our measurements inside the subestuaries to measurements by the Chesapeake Bay Program in adjacent estuarine waters outside the subestuaries. TP and dissolved inorganic P concentrations inside the subestuaries correlated with concentrations outside the subestuaries. However, water quality inside the subestuaries generally differed from that in adjacent estuarine waters. The concentration of nitrate was lower inside the subestuaries, while the concentrations of other forms of N, TP, and chlorophyll a were higher. This suggests that shallow nearshore waters inside the subestuaries import nitrate while exporting other forms of N as well as TP and chlorophyll a. The importance of local land use and the distinct biogeochemistry of shallow waters should be considered in managing coastal systems.
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Liu, Yang, Jun Bi, and Jianshu Lv. "Future Impacts of Climate Change and Land Use on Multiple Ecosystem Services in a Rapidly Urbanizing Agricultural Basin, China." Sustainability 10, no. 12 (December 4, 2018): 4575. http://dx.doi.org/10.3390/su10124575.
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Ecosystem services (ESs) in rapidly urbanizing agricultural basins are vulnerable to environmental changes. Adequately understanding the driving forces and the dynamics of ESs related to water quantity and quality can provide a basis for making sound management decisions on the development of basins. Here, we explored the impacts of future land use and climate changes on four ESs: nitrogen and phosphorous purification, water supply, and soil retention services in the Taihu Basin region of eastern China. Spatially explicit methods, a cellular automata-Markov (CA-Markov) model and the delta downscaling method were used to quantify the ESs, simulate land use changes, and project future climate changes, respectively. We built a business-as-usual land use scenario, representative concentration pathways (RCPs) scenarios for climate change, as well as a combined land use and climate change scenario to analyze the changes in the drivers and the responses of ESs. The results showed the following: (1) future land use changes would significantly enhance the nitrogen purification service while reducing the phosphorus purification service compared to other services; (2) climate change would have substantial effects on water supply and soil retention, but these impacts would vary with different RCPs scenarios during three future periods; and (3) the combined scenarios of both drivers would obviously influence all ESs and lead to a nitrogen purification service that was different from the other three services. Moreover, the policy implications of the results were discussed. The findings can help guide the creation of policies for land structure and patterns, climate change adaptation, and ecosystem-based management to promote the sustainable development of watersheds at the regional scale.
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de Lima Barros, Alessandra Maciel, Maria do Carmo Sobral, and Günter Gunkel. "Modelling of point and diffuse pollution: application of the Moneris model in the Ipojuca river basin, Pernambuco State, Brazil." Water Science and Technology 68, no. 2 (July 1, 2013): 357–65. http://dx.doi.org/10.2166/wst.2013.086.
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Emissions of pollutants and nutrients are causing several problems in aquatic ecosystems, and in general an excess of nutrients, specifically nitrogen and phosphorus, is responsible for the eutrophication process in water bodies. In most developed countries, more attention is given to diffuse pollution because problems with point pollution have already been solved. In many non-developed countries basic data for point and diffuse pollution are not available. The focus of the presented studies is to quantify nutrient emissions from point and diffuse sources in the Ipojuca river basin, Pernambuco State, Brazil, using the Moneris model (Modelling Nutrient Emissions in River Systems). This model has been developed in Germany and has already been implemented in more than 600 river basins. The model is mainly based on river flow, water quality and geographical information system data. According to the Moneris model results, untreated domestic sewage is the major source of nutrients in the Ipojuca river basin. The Moneris model has shown itself to be a useful tool that allows the identification and quantification of point and diffuse nutrient sources, thus enabling the adoption of measures to reduce them. The Moneris model, conducted for the first time in a tropical river basin with intermittent flow, can be used as a reference for implementation in other watersheds.
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Abimbola, Olufemi, Aaron Mittelstet, Tiffany Messer, Elaine Berry, and Ann van Griensven. "Modeling and Prioritizing Interventions Using Pollution Hotspots for Reducing Nutrients, Atrazine and E. coli Concentrations in a Watershed." Sustainability 13, no. 1 (December 24, 2020): 103. http://dx.doi.org/10.3390/su13010103.
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Excess nutrients and herbicides remain two major causes of waterbody impairment globally. In an attempt to better understand pollutant sources in the Big Sandy Creek Watershed (BSCW) and the prospects for successful remediation, a program was initiated to assist agricultural producers with the implementation of best management practices (BMPs). The objectives were to (1) simulate BMPs within hotspots to determine reductions in pollutant loads and (2) to determine if water-quality standards are met at the watershed outlet. Regression-based load estimator (LOADEST) was used for determining sediment, nutrient and atrazine loads, while artificial neural networks (ANN) were used for determining E. coli concentrations. With respect to reducing sediment, total nitrogen and total phosphorus loads at hotspots with individual BMPs, implementing grassed waterways resulted in average reductions of 97%, 53% and 65% respectively if implemented all over the hotspots. Although reducing atrazine application rate by 50% in all hotspots was the most effective BMP for reducing atrazine concentrations (21%) at the gauging station 06883940, this reduction was still six times higher than the target concentration. Similarly, with grassed waterways established in all hotspots, the 64% reduction in E. coli concentration was not enough to meet the target at the gauging station. With scaled-down acreage based on the proposed implementation plan, filter strip led to more pollutant reductions at the targeted hotspots. Overall, a combination of filter strip, grassed waterway and atrazine rate reduction will most likely yield measureable improvement both in the hotspots (>20% reduction in sediment, total nitrogen and total phosphorus pollution) and at the gauging station. Despite the model’s uncertainties, the results showed a possibility of using Soil and Water Assessment Tool (SWAT) to assess the effectiveness of various BMPs in agricultural watersheds.
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Heartsill Scalley, T., F. N. Scatena, S. Moya, and A. E. Lugo. "Long-term dynamics of organic matter and elements exported as coarse particulates from two Caribbean montane watersheds." Journal of Tropical Ecology 28, no. 2 (February 13, 2012): 127–39. http://dx.doi.org/10.1017/s0266467411000733.
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Abstract:In heterotrophic streams the retention and export of coarse particulate organic matter and associated elements are fundamental biogeochemical processes that influence water quality, food webs and the structural complexity of forested headwater streams. Nevertheless, few studies have documented the quantity and quality of exported organic matter over multiple years and under a range of conditions that includes both droughts and hurricanes. This study quantifies the export of coarse particulate organic matter (CPOM, > 12.7 mm), over 18 y in two headwater streams in north-east Puerto Rico. Daily exports ranged from 0 to over 170 g ha−1 d−1 and averaged 7.39 g ha−1 d−1, with similar amounts coming from leaves (3.5 g ha−1 d−1) and wood (3.2 g ha−1 d−1). Export of coarse particulate organic carbon was 3.0 g ha−1 d−1 which constitutes only 1.32% of carbon exports. Most litter falling into the streams was processed in place as only 2.3% of the leaf litter falling directly into these perennial channels was exported as CPOM. On average, 6 wk y−1 had no exports while events transporting more than 10 g ha−1 d−1 occurred every 2.8 mo. Instead of a single annual pulse as observed in deciduous systems, there were annual peaks in CPOM exports during May and September and less export during the drier period from December to February. Ratios of C:N in the exported material were highest in the driest month and lowest during rainy months, while leaf fluxes for nitrogen, phosphorus and calcium were highest in rainy months and lowest during February. Although median daily exports and exports during low- and base-flow periods were similar before and after Hugo, after 16 y exports during moderate- and high-flow periods were still less than those in the 2 y prior to the hurricane. Our observations indicate a system with high rates of internal processing that quickly returns to median daily conditions following hurricanes but requires several decades for storm-flow exports to return to pre-disturbance conditions and indicates that the long-term pattern of CPOM export is associated with the level of maturity of watershed vegetation.
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Salla, Marcio Ricardo, Nathália Barcelos Cunha, and Sérgio Siqueira Prado Soares. "Modelagem de qualidade da água no rio São Marcos, bacia hidrográfica do alto Paraná." Revista DAE 221, no. 68 (December 10, 2019): 20–41. http://dx.doi.org/10.36659/dae.2020.003.
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A bacia hidrográfica do rio São Marcos, localizada no alto Paraná entre os estados de Goiás e Minas Gerais e o Distrito Federal, apresenta conflito hídrico de grande relevância entre o setor hidrelétrico (operação em cascata das centrais hidrelétricas Batalha – potencial de 52,5 MW e Serra do Facão – potencial de 210 MW) e o setor agrícola (total outor- gado de 65,7 hm3/mês em meados de 2017). O objetivo deste artigo foi avaliar a carga máxima afluente de amônia, nitrato e fósforo total que os reservatórios suportam para ainda se enquadrar aos limites definidos na Resolução Co- nama 357:2005. A calibração do modelo a partir da ferramenta AQUATOOL, entre outubro de 2014 e setembro de 2017, forneceu bom ajuste entre as simulações e os dados medidos (para os parâmetros OD, DBO, nitrogênio orgâni- co, amônia, nitrato e fósforo total) em quatro postos de monitoramento. Os cenários mostraram capacidade máxima de aporte de 4,19, 9,18 e 0,055 ton/km2.mês de amônia, nitrato e fósforo total, respectivamente, para as sub-bacias de contribuição de Batalha e de 1,30, 3,34 e 0,019 ton/km2.mês de amônia, nitrato e fósforo total, respectivamente, nas sub-bacias de contribuição de Serra do Facão, todas a jusante do reservatório de Batalha. De forma geral, o estu- do contribui para o planejamento e gestão de uso e ocupação do solo na bacia hidrográfica do rio São Marcos. Palavras-chave: Modelagem. Conflito hídrico. AQUATOOL. Rio São Marcos. Uso e ocupação do solo. São Marcos river watershed is located in the state of Paraná, Brazil, between the states of Goiás, Minas Gerais and the Federal District. It presents a relevant hydric conflict between the hydroe-lectric sector (cascade operation of the Batalha hydroelectric plant - 52.5 MW of potential and Serra do Facão - 210 MW of potential) and the agricultural sector (grant- ed of 65.7 hm3/month in 2017). This article aimed to assess the maximum affluent total load of ammonia, nitrate and phosphorus that the dams support and still be framed within the limits defined in the 357:2005 Conama Resolution. The model's calibration in AQUATOOL computational tool, between October 2014 and September 2017, provided a good ad- justment between the simulations and the measured data ( for the OD, DBO, organic nitrogen, ammonia, nitrate and total phosphorus) in four monitoring positions located in São Marcos River. The scenario has showed a maximum contribution capacity of 4.19, 9.18 e 0.055 ton/km2.month of ammonia, nitrate and total phosphorus, respectively, in the contribu- tions sub watersheds in Batalha and of 1.30, 3.34 and 0.019 ton/km2.month of ammonia, nitrate and phosphorus in the contributions sub watersheds in Serra do Facão. In general, the study contributed for the planning and management of the soil use and occupation on the watershed.
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Jones, Erin Fleming, Rebecca J. Frei, Raymond M. Lee, Jordan D. Maxwell, Rhetta Shoemaker, Andrew P. Follett, Gabriella M. Lawson, et al. "Citizen science reveals unexpected solute patterns in semiarid river networks." PLOS ONE 16, no. 8 (August 19, 2021): e0255411. http://dx.doi.org/10.1371/journal.pone.0255411.
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Human modification of water and nutrient flows has resulted in widespread degradation of aquatic ecosystems. The resulting global water crisis causes millions of deaths and trillions of USD in economic damages annually. Semiarid regions have been disproportionately affected because of high relative water demand and pollution. Many proven water management strategies are not fully implemented, partially because of a lack of public engagement with freshwater ecosystems. In this context, we organized a large citizen science initiative to quantify nutrient status and cultivate connection in the semiarid watershed of Utah Lake (USA). Working with community members, we collected samples from ~200 locations throughout the 7,640 km2 watershed on a single day in the spring, summer, and fall of 2018. We calculated ecohydrological metrics for nutrients, major ions, and carbon. For most solutes, concentration and leverage (influence on flux) were highest in lowland reaches draining directly to the lake, coincident with urban and agricultural sources. Solute sources were relatively persistent through time for most parameters despite substantial hydrological variation. Carbon, nitrogen, and phosphorus species showed critical source area behavior, with 10–17% of the sites accounting for most of the flux. Unlike temperate watersheds, where spatial variability often decreases with watershed size, longitudinal variability showed an hourglass shape: high variability among headwaters, low variability in mid-order reaches, and high variability in tailwaters. This unexpected pattern was attributable to the distribution of human activity and hydrological complexity associated with return flows, losing river reaches, and diversions in the tailwaters. We conclude that participatory science has great potential to reveal ecohydrological patterns and rehabilitate individual and community relationships with local ecosystems. In this way, such projects represent an opportunity to both understand and improve water quality in diverse socioecological contexts.
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Yoshikawa, Seiko, Donglai Ma, Tadamasa Saito, Kenji Matsumori, Yuko Itoh, Kazunori Kohyama, and Masahiro Kobayashi. "Calculation of SS, TN and TP Specific Concentration Factors for Land-Use Types Using a Simple Watershed Model." Journal of Sustainable Development 12, no. 5 (September 29, 2019): 138. http://dx.doi.org/10.5539/jsd.v12n5p138.
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To contribute to the prediction of rainfall-related disasters, specific concentration factors that indicate the suspended solid (SS), total nitrogen (TN), and total phosphorus (TP) load intensities to river water for each land-use type were calculated using a simple watershed land-use model across Japan by applying the following multiple regression equation, according to the land-use ratios and published SS, TN and TP data.
C=i=14aixi
C: SS, TN and TP concentrations (mg L-1); ai: SS, TN and TP specific concentration factor for land use i; xi: ratio of land use i; land use: 1 paddy fields, 2 upland fields, 3 forests, 4 urban areas.
The land-use ratios for watersheds, whose lower ends were observation points of river water quality, were determined by the GIS technique using a published database of DEM and LULC mesh data. The SS specific concentration factor was 15.4 (from a 95% lower limit value of 12.0 to a 95% upper limit value of 18.8), 11.5 (7.4 to 15.6), 3.9 (2.6 to 5.1), and 11.2 (9.2 to 13.2) for paddy fields, upland fields, forests and urban areas, respectively (n=5103). The TN specific concentration factor was 1.67 (from a 95% lower limit value of 1.34 to a 95% upper limit value of 2.01), 4.08 (3.64 to 4.51), 0.76 (0.67 to 0.90), and 3.57 (3.38 to 3.76) for paddy fields, upland fields, forests and urban areas, respectively (n=3256). The TP specific concentration factor was 0.146 (from a 95% lower limit value of 0.119 to a 95% upper limit value of 0.172), 0.172 (0.138 to 0.206), 0.044 (0.033 to 0.055), and 0.267 (0.253 to 0.282) for paddy fields, upland fields, forests and urban areas, respectively (n=3256). These specific concentration factors had regional tendencies, such as suburban or rural, intensive or extensive agriculture, and so on.
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Lu, Jiangang, Haisheng Cai, Xueling Zhang, and Yanmei Fu. "Water quality in relation to land use in the Junshan Lake watershed and water quality predictions." Water Supply, April 28, 2021. http://dx.doi.org/10.2166/ws.2021.123.
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Abstract Changes in human-dominated spatial patterns of land use are the main driving factors of water quality evolution in watersheds, and the quantitative impact of land use changes on water quality is currently a focus of lake ecology research. Using the Junshan Lake Basin as a study area, this paper quantitatively analyzes the response relationships between the water quality parameters, land use, and socio-economic factors in the study area from 2005 to 2019 and predicts the water quality in 2035 based on land and space planning scenarios. The results show the following. (1) The land use structure of the Junshan Lake Basin has changed significantly over the last 15 years. The basic trend is an increase in settlement and wetland areas in the basin and a decrease in water, cropland, forest, and grassland areas. (2) Settlement areas play the role of a ‘source’ for the total phosphorus (TP) and ammonium-nitrogen (NH3-N) pollution load, and cropland areas play the role of a ‘sink’ for the TP, NH3-N, and chemical oxygen demand (CODMn) pollution load. (3) The main land use type in the Junshan Lake Basin is cropland, which accounts for more than 40% of the total, and the water quality in the lake is affected not only by non-point source pollution but also by the regional Gross Domestic Product (GDP), total population, and per capita disposable income. According to the water quality prediction and analysis, the concentrations of TN and TP in Junshan Lake will meet the Class IV water quality standard in 2035, and the concentrations of dissolved oxygen (DO) and CODMn will meet the Class II standard. This study is significant for the management and control of the water environment in the Junshan Lake Basin.