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1
Deinkuro, Nimisingha Sanchez, Charles William Knapp, Morufu Olalekan Raimi, and Nanlok Henry Nimlang. "Environmental Fate of Toxic Volatile Organics from Oil Spills in the Niger Delta Region, Nigeria." International Journal of Environment, Engineering & Education 3, no. 3 (2021): 89–101. https://doi.org/10.5281/zenodo.5842939.
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Over the years, the environmental degradation of ecological resources from crude oil pollution and its human health impacts is receiving more global attention. The utilization of environmental models capable of predicting the fate, transport, and toxicity of chemicals in spilt crude oil can provide essential knowledge required to deal with the complexity associated with the fate of volatile petroleum chemicals in the environment. This paper explores the environmental fate of toxic volatile organics from an oil spill in the Niger Delta Region of Nigeria. Results from the literature implicated sabotage and operational failures from pipelines as primary causes of crude oil spillages. The generation of a fugacity model using EPI Suite™ revealed that Koc values greatly influence the behavior of BTN. Benzene, Toluene, and Naphthalene (BTN) were partitioned into three compartments based on organic-carbon partitioning coefficient (Koc). The organic-carbon partitioning coefficient (Koc) was computed as a function of soil-water distribution coefficient (Kd) and percentage organic matter (%OM). Koc was used to determining the possible risk posed on delicate ecological resources. Aquatic toxicology estimation using Ecological Structural Activity Relationship revealed that all chemicals were not toxic even at over-estimated Koc values. This research established the usefulness of screening level environmental modeling tools in assessing ecological risk and hence helpful in developing site-specific models for monitoring chemicals in the environment, which can assist governments, policymakers, and industries in designing appropriate regional disaster management plans.
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Deinkuro, Nimisingha Sanchez, Charles William Knapp, Morufu Olalekan Raimi, and Nanlok Henry Nimlang. "Environmental Fate of Toxic Volatile Organics from Oil Spills in the Niger Delta Region, Nigeria." International Journal of Environment, Engineering and Education 3, no. 3 (2021): 89–101. http://dx.doi.org/10.55151/ijeedu.v3i3.64.
Full textAbstract:
Over the years, the environmental degradation of ecological resources from crude oil pollution and its human health impacts is receiving more global attention. The utilization of environmental models capable of predicting the fate, transport, and toxicity of chemicals in spilt crude oil can provide essential knowledge required to deal with the complexity associated with the fate of volatile petroleum chemicals in the environment. This paper explores the environmental fate of toxic volatile organics from an oil spill in the Niger Delta Region of Nigeria. Results from the literature implicated sabotage and operational failures from pipelines as primary causes of crude oil spillages. The generation of a fugacity model using EPI Suite™ revealed that Koc values greatly influence the behavior of BTN. Benzene, Toluene, and Naphthalene (BTN) were partitioned into three compartments based on organic-carbon partitioning coefficient (Koc). The organic-carbon partitioning coefficient (Koc) was computed as a function of soil-water distribution coefficient (Kd) and percentage organic matter (%OM). Koc was used to determining the possible risk posed on delicate ecological resources. Aquatic toxicology estimation using Ecological Structural Activity Relationship revealed that all chemicals were not toxic even at over-estimated Koc values. This research established the usefulness of screening level environmental modeling tools in assessing ecological risk and hence helpful in developing site-specific models for monitoring chemicals in the environment, which can assist governments, policymakers, and industries in designing appropriate regional disaster management plans.
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Takigami, H., N. Taniguchi та Y. Shimizu. "Sorption and desorption of 17β-estradiol to natural sediment". Water Science and Technology 64, № 7 (2011): 1473–78. http://dx.doi.org/10.2166/wst.2011.527.
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The sorption and desorption of 17β-estradiol (E2) to various natural sediment were investigated. First, the quantitative solvent–water partition indices were measured. Significant differences were found between the n-octanol–water partition coefficient (KOW) and the n-hexane–water partition coefficient (KHW) of E2. The value of KHW (Log KHW = 0.07) is lower than those of two to four ring polyaromatic hydrocarbons (PAHs), while the value of KOW (Log KOW = 3.99) and that of organic matter–water partition coefficient (KOC) onto humic acid (Log KOC = 4.30) were similar to those of the PAHs. Five natural sediments of various characteristics and origins were selected for sorption and desorption experiments. Linear isotherms were obtained for sorption and desorption. The equilibrium partitioning coefficients of E2 were well-correlated with their values of weight fraction of organic carbon in sediments (fOC). Results suggest that E2 is sorbed mainly onto the organic portion of sediments and that its sorption coefficient can be estimated from KOW and fOC, as in the case of non-polar PAHs. However, because of its polarity, the sorption mechanism of E2 onto sediments cannot be explained solely by the hydrophobic interaction.
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Islam, Mohammad Showkatul, Hongde Zhou, and Richard G. Zytner. "Fate kinetic coefficients and correlation models for tetrabromobisphenol A (TBBPA) in membrane bioreactors and conventional activated sludge process." Journal of Water Reuse and Desalination 6, no. 1 (2015): 175–87. http://dx.doi.org/10.2166/wrd.2015.025.
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Tetrabromobisphenol A (TBBPA) is a fire retardant with endocrine disruption properties, which unfortunately has been detected in trace amounts in various environmental samples. Studies have shown that TBBPA enters the aquatic environment, sediments, soils and biota predominantly through the wastewater treatment process. The dominant contributor to the fate and transport of TBBPA in wastewater is biosorption by the sludge matrix. Accordingly, the goal of this research was to determine the fate kinetics, biosorption correlation models and mechanisms of TBBPA from both conventional activated sludge (CAS) and membrane bioreactor (MBR) systems. Experiments were conducted to determine different types of partitioning and fate kinetic coefficients such as solid–liquid phase coefficient, log Kp (4.53), sludge matrix organic carbon coefficient, log Koc (6.05) and glass wall partition coefficient, Kw (0.053). The experimental values of these coefficients for TBBPA are not available in the literature for application to the models. The biosorption data were also verified and fitted to Freundlich, Langmuir, Temkin, Toth, Redlich–Peterson, Sips, Brunauer–Emmett–Teller (BET), Jovanovic and Dubinin–Radushkevich biosorption isotherm models to estimate the isotherm constants. These coefficients will allow engineering application for validation of various fate models for TBBPA.
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He, J., and R. Balasubramanian. "The exchange of SVOCs across the air-sea interface in Singapore's coastal environment." Atmospheric Chemistry and Physics Discussions 9, no. 3 (2009): 13235–69. http://dx.doi.org/10.5194/acpd-9-13235-2009.
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Abstract. Coastal areas are vulnerable to the accumulation of semi-volatile organic compounds such as PAHs, OCPs and PCBs from atmospheric inputs. Dry particulate and wet depositions, and air-water diffusive exchange in the Singapore's south coastal area, where most of chemical and oil refinery industries are situated in, were estimated. Based on a yearly dataset, the mean annual dry particulate deposition fluxes of ∑16PAHs, ∑7OCPs and ∑21PCBs were 1328.8±961.1 μg m−2 y−1, 5421.4±3426.7 ng m−2 y−1 and 811.8±578.3 ng m−2 y−1, and the wet deposition of ∑16PAHs and ∑7OCPs were 6667.1±1745.2 and 115.4±98.3 μg m−2 y−1, respectively. Seasonal variation of atmospheric depositions was influenced by meteorological conditions. Air-water gas exchange fluxes had negative values for PAHs, HCHs and DDXs, indicating Singapore's south coast as a sink for the above-mentioned SVOCs. The relative contribution of each depositional process to the total atmospheric input was assessed by annual fluxes. The profile of dry particulate deposition, wet deposition and gas exchange fluxes seemed to be correlated with individual pollutant's properties such as molecular weight and Henry's law constant, etc. For the water column partitioning, the organic carbon-normalized partition coefficients between particulate and dissolved phases (KOC) for both PAHs and OCPs were obtained. The relationships between KOC of PAHs and OCPs and their respective octanol-water partition coefficient (KOW) were examined. In addition, both adsorption onto combustion-derived soot carbon and absorption into natural organic matter for PAHs in marine water column were investigated. Enrichment factors in the sea-surface microlayer (SML) of the particulate phase were 1.2~7.1 and 3.0~4.9 for PAHs and OCPs, and those of dissolved phase were 1.1~4.9 and 1.6~4.2 for PAHs and OCPs, respectively. These enrichment factors are relatively higher than those reported for nearby coastal areas, which are most likely due to more organic surfactants floating in the south coastal surface of Singapore.
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He, J., and R. Balasubramanian. "The exchange of SVOCs across the air-sea interface in Singapore's coastal environment." Atmospheric Chemistry and Physics 10, no. 4 (2010): 1837–52. http://dx.doi.org/10.5194/acp-10-1837-2010.
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Abstract. Coastal areas are vulnerable to the accumulation of semivolatile organic compounds, such as PAHs, OCPs and PCBs from atmospheric inputs. Dry particulate and wet depositions, and air-water diffusive exchange in the Singapore's south coastal area, where most of chemical and oil refinery industries are situated in, were estimated. Based on a yearly dataset, the mean annual dry particulate deposition fluxes of ∑16-PAHs, ∑7 OCPs and ∑21 PCBs were 1328.8±961.1 μg m−2 y−1, 5421.4±3426.7 ng m−2 y−1 and 811.8±578.3 ng m−2 y−1, and the wet deposition of ∑16-PAHs and ∑7 OCPs were 6667.1±1745.2 and 115.4±98.3 μg m−2 y−1, respectively. Seasonal variation of atmospheric depositions was influenced by meteorological conditions. Air-water gas exchange fluxes were shown to be negative values for PAHs, HCHs and DDXs, indicating Singapore's south coast as a sink for the above-mentioned SVOCs. The relative contribution of each depositional process to the total atmospheric input was assessed by annual fluxes. The profile of dry particulate deposition, wet deposition and gas exchange fluxes seemed to be correlated with individual pollutant's properties such as molecular weight and Henry's law constant, etc. For the water column partitioning, the organic carbon-normalized partition coefficients between particulate and dissolved phases (KOC) for both PAHs and OCPs were obtained. The relationships between KOC of PAHs and OCPs and their respective octanol-water partition coefficient (KOW) were examined. In addition, both adsorption onto combustion-derived soot carbon and absorption into natural organic matter for PAHs in marine water column were investigated. Enrichment factors in the sea-surface microlayer (SML) of the particulate phase were 1.2–7.1 and 3.0–4.9 for PAHs and OCPs, and those of dissolved phase were 1.1–4.9 and 1.6–4.2 for PAHs and OCPs, respectively. These enrichment factors are relatively higher than those reported for nearby coastal areas, which are most likely due to more organic surfactants floating in the south coastal surface of Singapore.
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Mörtl, Mária, Orsolya Kereki, Béla Darvas, et al. "Study on Soil Mobility of Two Neonicotinoid Insecticides." Journal of Chemistry 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/4546584.
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Movement of two neonicotinoid insecticide active ingredients, clothianidin (CLO) and thiamethoxam (TMX), was investigated in different soil types (sand, clay, or loam) and in pumice. Elution profiles were determined to explore differences in binding capacity. Soil characterized by high organic matter content retained the ingredients, whereas high clay content resulted in long release of compounds. Decrease in concentration was strongly influenced by soil types: both CLO and TMX were retained in loam and clay soils and showed ready elution through sandy soil and pumice. Elution capability of the active ingredients in sandy soil correlated with their water solubility, indicating approximately 30% higher rapidity for TMX than for CLO. Soil organic carbon-water partitioning coefficients (Koc) determined were in good agreement with literature values with somewhat lower value for CLO in sandy soil and substantially higher values for TMX in clay soil. High mobility of these neonicotinoid active ingredients in given soil types urges stronger precautionary approach taken during their application.
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Willett, Cammy D., Erin M. Grantz, Matthew G. Sena, Jung Ae Lee, Kristofor R. Brye, and Jessica A. Clarke. "Soil sorption characteristics of benzobicyclon hydrolysate and estimated leaching risk in soils used for rice production." Environmental Chemistry 17, no. 6 (2020): 445. http://dx.doi.org/10.1071/en19189.
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Environmental contextThe behaviour of herbicides in the environment is largely determined by the partitioning of the compounds between soil solids and soil solution. We determined that the rice herbicide-metabolite benzobicyclon hydrolysate partitions more into soil solution, and does so increasingly as pH increases. These results indicate that benzobicyclon hydrolysate is a risk for leaching in much of the rice-producing area in the US mid-South. AbstractBenzobicyclon hydrolysate (BH) is the major metabolite and active molecule in the pro-herbicide benzobicyclon (BZB), which is pending registration for use in US mid-Southern rice (Oryza sativa L.) production. The current study objectives were to (i) determine BH soil sorption coefficients; (ii) quantify relationships among BH sorption and soil properties; and (iii) estimate leaching potential using calculated retardation factors (RFs). Sorption coefficients for 10 representative Arkansas rice-production soils were determined by batch-equilibration experiments. Soil sorption (KD=0.25–44.3mLg−1), soil organic carbon partitioning (KOC=28.2–7480mLg−1), and soil organic matter partitioning (KOM=17.9–2580mLg−1) coefficients were negatively correlated with soil pH (r=−0.93 – −0.94). Clay and silt were significant secondary regression parameters, accounting for up to 93% of the variation in KD in combination with pH. Clay and silt effects on sorption coefficients increased when regression analyses excluded the lowest pH soil. Soil sorption coefficients were greater in soils with clay ≥27%, which may be a useful parameter for informing herbicide-use rates. Using the calculated RF’s, the estimated depth of leaching over the growing season exceeded the assumed 15-cm plough layer depth in eight of the 10 soils, and only two of the 10 soils had an estimated time to plough layer breakthrough less than the typical six-month growing season (April–September) under average water flux conditions. The results suggest that BH leaching below the plough layer is a potential risk for much of the rice-producing area in the US mid-South.
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Mitrić, Siniša, Mihajlo Marković, Mladen Babić, Milan Šipka, Dušica Pešević, and Duško Dragićević. "PHYSICAL-CHEMICAL CHARACTERISTICS OF HERBICIDES USED FOR MAIZE PRODUCTION IN BIH AS FACTORS OF POTENTIAL HERBICIDE LEACHING IN GROUNDWATER." Radovi Šumarskog fakulteta Univerziteta u Sarajevu 21, no. 1 (2016): 297–305. http://dx.doi.org/10.54652/rsf.2016.v1.i1.306.
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UDK 631.4:632.954; 633.1:632.954(497.6)
 The aim of the study is to present the elements which must be considered while determining the risk of the mobility of the herbicides. Herbicides used for maize production have the special eco toxical significance and special risk because some are potentially mobile, they are used on the large surfaces during the rainy period and near rivers.
 Behaviour of the herbicides in the environment, particularly in the soil is very complex. It does not depend only on the characteristics of the herbicide, but on the many factors of the environment which are very variable. Regardless of this fact, there are experimentally determined physical-chemical indicators for each herbicide that show the possible behaviour of herbicides in the environment. Studied physical-chemical indicators of herbicide behavior are: Distribution Coefficient (Kd); Organic Carbon Partitioning Coefficient (Koc); Time of the Semi-Decomposition (DT50); Water Solubility (S); Groundwater Ubiquity Score (GUS); Henry's Law Constant (Kh), Vapor Pressure (PV) and the Dissociation Constant (pKa).
 Namely, herbicides, in larger or smaller measure, have “leaching potential“, which is ability to reach the underground water. One of the basic criteria for evaluating the herbicide ability to reach the underground water is related to indicators of mobility and persistency (DT50) herbicides, but neglecting some other criteria in that evaluation such as the amount of applying, characteristics of the soil and the aim of the crop growth. According to the EPA criteria, for the herbicides used in maize production in Bosnia and Herzegovina (BiH), the “trigger“ value will indirectly indicate if the herbicides have large leaching potential.
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Ahn, Jeonghyeon, Guiying Rao, Mustafa Mamun, and Eric P. Vejerano. "Soil–air partitioning of volatile organic compounds into soils with high water content." Environmental Chemistry 17, no. 8 (2020): 545. http://dx.doi.org/10.1071/en20032.
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Environmental contextAssessing environmental and human health impacts of chemical spills relies on information about how chemicals move across multiple environments. We measured volatile contaminants in the air above soil saturated with water to provide estimates of air concentrations of selected chemicals released to soil from an oil refinery in Texas during Hurricane Harvey. Estimated concentrations were below recommended exposure limits, even in a worst-case scenario. AbstractThe emission of volatile organic compounds (VOCs) from soil into air is affected by soil moisture dynamics, soil temperature, solar irradiance and carbon availability. The high amount of water in soil can modify its properties, which changes how VOCs interact. We conducted a comprehensive measurement of the soil–air partition coefficient (KSA) of VOCs into water-saturated soil with both low and high water contents for polar, weakly polar and nonpolar VOCs into a mineral soil (S-clay) and soil containing a high amount of organic matter (S-om) under a water-saturated condition. Partitioning of non-polar substituted aromatics (1,2-dichlorobenzene and toluene) was sensitive to the organic matter content in water-saturated soil. 1,2-Dichlorobenzene and toluene had higher affinities to S-om than to S-clay at all investigated water contents because of their strong interaction with the organic matter in soil. KSA decreased with elevated water content only for non-polar substituted aromatic VOCs. Less hydrophobic VOCs (benzene and trichloroethylene) exhibited similar partitioning into both soils by sorbing onto the air-water interface and dissolving in soil water, while the organic matter did not affect partitioning. The weakly polar and polar VOCs (methyl tert-butyl ether and 1-butanol) showed similar partitioning into both soils by dissolving in soil water while sorption to the organic matter was significant only at high soil water contents. KSA of VOCs on soil with high organic matter content correlated strongly with psat and Koa, but not on mineral soil. Estimates of the air concentrations for a subset of VOCs released from one refinery during Hurricane Harvey in 2017 in Harris County, Texas were lower than the recommended exposure limits, even under a worst-case scenario.
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Quadir, Quazi Forhad, and Atiqur Rahman. "Sorption kinetics of isoproturon and assessment of its Ecotoxicity on Lemna minor." Research in Agriculture Livestock and Fisheries 1, no. 1 (2015): 13–18. http://dx.doi.org/10.3329/ralf.v1i1.22347.
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The study was carried out to investigate the ecotoxicity of Isoproturon on Lemna minor and the interaction of the EC50 value of the chemical with sorption behaviour of the chemical in soil. The sorption isotherms (Kf and KOC) for Isoproturon were determined for three different soils having various organic carbon and clay content. EC50 for Lemna was determined both with and without soil. Both the Freundlich adsorption coefficient (Kf) and normalized sorption coefficient (KOC) values varied with different types of soil. There was moderate correlation between the log Kf and log KOC existed. The regression study revealed a strong relationship between log KOC and organic carbon and between log KOC and soil clay content. There EC50 value for Lemna grown with soil was higher than that grown without soil. However, the difference was statistically insignificant. Greater degree of inconsistency in various data suggests the reiteration of the study.DOI: http://dx.doi.org/10.3329/ralf.v1i1.22347 Res. Agric., Livest. Fish.1(1): 13-18, Dec 2014
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Chen, Z., W. B. McGill, M. J. Dudas та B. Xing. "α-Naphthol sorption as regulated by structure and composition of organic substances in soils and sediments". Canadian Journal of Soil Science 76, № 4 (1996): 513–22. http://dx.doi.org/10.4141/cjss96-064.
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Humic acids (HAs) from major horizons of a Gleyed Black Chernozem and a set of soil and sediment samples were examined to understand the influence of the structure a composition of organic substances on sorption of organic pollutants. Solid state 13C cross-polarized/magic angle spinning (CP/MAS) NMR results indicated that the aromaticity of HAs increased with soil depth. The aromaticity of organic substances in bulk soils and sediments varied with the degree of geological diagenesis. Sorption experiments showed a linear relationship between the carbon normalized partition coefficient (Koc) of α-naphthol and the aromaticity of HAs and non-extracted organic substances in whole soils and sediments. The Koc values of α-napthol had a log-linear relationship with the atomic mass ratio (N+O)/C of the organic substances in soils and sediments. Correlation analysis for the literature data further revealed that the compositional and structural properties of organic substances were related, suggesting possibilities of predicting Koc with either compositional or structural parameters Measured Koc values demonstrated considerable deviations from those calculated with prediction models using Kow. The prediction models may not be accurate because they do not account for the compositional and structural differences in organic substances of sorbents. Key words: sorption, organic substances, aromaticity, Koc, α-naphthol
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Brusseau, Mark L. "Differential Sorption of Short-Chain versus Long-Chain Anionic Per- and Poly-Fluoroalkyl Substances by Soils." Environments 10, no. 10 (2023): 175. http://dx.doi.org/10.3390/environments10100175.
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The impact of chain length on the sorption of anionic PFAS by soils and sediments was investigated by aggregating and synthesizing data sets from the literature. Quantitative structure/property relationship (QSPR) analysis was applied to characterize the influence of molecular size and soil properties on sorption. The log of the organic carbon-normalized equilibrium sorption coefficient (Koc) exhibited a biphasic relationship with molar volume, wherein the log Koc values for the short-chain PFAS were generally greater than would be predicted using the QSPR correlation determined for the long-chain PFAS. This enhanced differential sorption is observed to different degrees for all studies, which are compiled and synthesized for the first time. The results reveal remarkable congruency across a wide array of soils comprising a large range of properties and indicate that the observed enhanced differential sorption of short-chain PFAS is a prevalent phenomenon. Aggregating the long-chain PFAS data for all soils and sediments with organic carbon contents > 1% produced a strong correlation, indicating that the resultant QSPR model can produce representative log Koc values irrespective of the other properties of the medium. Silt+clay content was shown to be an important soil component for the short-chain PFAS for most soils, as well as the long-chain PFAS for soils with organic carbon contents < 1%. The results indicate that while the simple Koc-foc approach may produce reasonable estimates of Kd values for long-chain anionic PFAS, particularly for soils and sediments with larger organic carbon contents, it is unlikely to do so for short-chain anionic PFAS.
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Jiang, Lan, Yue Xu, Xiaoyu Zhang, Bingfeng Xu, Ximeng Xu, and Yixing Ma. "Developing a QSPR Model of Organic Carbon Normalized Sorption Coefficients of Perfluorinated and Polyfluoroalkyl Substances." Molecules 27, no. 17 (2022): 5610. http://dx.doi.org/10.3390/molecules27175610.
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Perfluorinated and polyfluoroalkyl substances (PFASs) are known for their long-distance migration, bioaccumulation, and toxicity. The transport of PFASs in the environment has been a source of increasing concerned. The organic carbon normalized sorption coefficient (Koc) is an important parameter from which to understand the distribution behavior of organic matter between solid and liquid phases. Currently, the theoretical prediction research on log Koc of PFASs is extremely limited. The existing models have limitations such as restricted application fields and unsatisfactory prediction results for some substances. In this study, a quantitative structure–property relationship (QSPR) model was established to predict the log Koc of PFASs, and the potential mechanism affecting the distribution of PFASs between two phases from the perspective of molecular structure was analyzed. The developed model had sufficient goodness of fit and robustness, satisfying the model application requirements. The molecular weight (MW) related to the hydrophobicity of the compound; lowest unoccupied molecular orbital energy (ELUMO) and maximum average local ionization energy on the molecular surface (ALIEmax), both related to electrostatic properties; and the dipole moment (μ), related to the polarity of the compound; are the key structural variables that affect the distribution behavior of PFASs. This study carried out a standardized modeling process, and the model dataset covered a comprehensive variety of PFASs. The model can be used to predict the log Koc of conventional and emerging PFASs effectively, filling the data gap of the log Koc of uncommon PFASs. The explanation of the mechanism of the model has proven to be of great value for understanding the distribution behavior and migration trends of PFASs between sediment/soil and water, and for estimating the potential environmental risks generated by PFASs.
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Li, Y. F., W. L. Ma, and M. Yang. "Prediction of gas/particle partitioning of polybrominated diphenyl ethers (PBDEs) in global air: A theoretical study." Atmospheric Chemistry and Physics 15, no. 4 (2015): 1669–81. http://dx.doi.org/10.5194/acp-15-1669-2015.
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Abstract. Gas/particle (G/P) partitioning of semi-volatile organic compounds (SVOCs) is an important process that primarily governs their atmospheric fate, long-range atmospheric transport, and their routes of entering the human body. All previous studies on this issue are hypothetically based on equilibrium conditions, the results of which do not predict results from monitoring studies well in most cases. In this study, a steady-state model instead of an equilibrium-state model for the investigation of the G/P partitioning behavior of polybrominated diphenyl ethers (PBDEs) was established, and an equation for calculating the partition coefficients under steady state (KPS) of PBDEs (log KPS = log KPE + logα) was developed in which an equilibrium term (log KPE = log KOA + logfOM −11.91 where fOM is organic matter content of the particles) and a non-equilibrium term (log α, caused by dry and wet depositions of particles), both being functions of log KOA (octanol–air partition coefficient), are included. It was found that the equilibrium is a special case of steady state when the non-equilibrium term equals zero. A criterion to classify the equilibrium and non-equilibrium status of PBDEs was also established using two threshold values of log KOA, log KOA1, and log KOA2, which divide the range of log KOA into three domains: equilibrium, non-equilibrium, and maximum partition domain. Accordingly, two threshold values of temperature t, tTH1 when log KOA = log KOA1 and tTH2 when log KOA = log KOA2, were identified, which divide the range of temperature also into the same three domains for each PBDE congener. We predicted the existence of the maximum partition domain (the values of log KPS reach a maximum constant of −1.53) that every PBDE congener can reach when log KOA ≥ log KOA2, or t ≤ tTH2. The novel equation developed in this study was applied to predict the G/P partition coefficients of PBDEs for our Chinese persistent organic pollutants (POPs) Soil and Air Monitoring Program, Phase 2 (China-SAMP-II) program and other monitoring programs worldwide, including in Asia, Europe, North America, and the Arctic, and the results matched well with all the monitoring data, except those obtained at e-waste sites due to the unpredictable PBDE emissions at these sites. This study provided evidence that the newly developed steady-state-based equation is superior to the equilibrium-state-based equation that has been used in describing the G/P partitioning behavior over decades. We suggest that the investigation on G/P partitioning behavior for PBDEs should be based onsteady-state, not equilibrium state, and equilibrium is just a special case of steady-state when non-equilibrium factors can be ignored. We also believe that our new equation provides a useful tool for environmental scientists in both monitoring and modeling research on G/P partitioning of PBDEs and can be extended to predict G/P partitioning behavior for other SVOCs as well.
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Li, Y. F., W. L. Ma, and M. Yang. "Prediction of gas/particle partitioning of polybrominated diphenyl ethers (PBDEs) in global air: a theoretical study." Atmospheric Chemistry and Physics Discussions 14, no. 16 (2014): 23415–51. http://dx.doi.org/10.5194/acpd-14-23415-2014.
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Abstract. Gas/particle (G / P) partitioning for most semivolatile organic compounds (SVOCs) is an important process that primarily governs their atmospheric fate, long-range atmospheric transport potential, and their routs to enter human body. All previous studies on this issue have been hypothetically derived from equilibrium conditions, the results of which do not predict results from monitoring studies well in most cases. In this study, a steady-state model instead of an equilibrium-state model for the investigation of the G / P partitioning behavior for polybrominated diphenyl ethers (PBDEs) was established, and an equation for calculating the partition coefficients under steady state (KPS) for PBDE congeners (log KPS = log KPE + logα) was developed, in which an equilibrium term (log KPE = log KOA + logfOM −11.91, where fOM is organic matter content of the particles) and a nonequilibrium term (logα, mainly caused by dry and wet depositions of particles), both being functions of log KOA (octanol-air partition coefficient), are included, and the equilibrium is a special case of steady state when the nonequilibrium term equals to zero. A criterion to classify the equilibrium and nonequilibrium status for PBDEs was also established using two threshold values of log KOA, log KOA1 and log KOA2, which divide the range of log KOA into 3 domains: equilibrium, nonequilibrium, and maximum partition domains; and accordingly, two threshold values of temperature t, tTH1 when log KOA = log KOA1 and tTH2 when log KOA = log KOA2, were identified, which divide the range of temperature also into the same 3 domains for each BDE congener. We predicted the existence of the maximum partition domain (the values of log KPS reach a maximum constant of −1.53) that every PBDE congener can reach when log KOA ≥ log KOA2, or t ≤ tTH2. The novel equation developed in this study was applied to predict the G / P partition coefficients of PBDEs for the published monitoring data worldwide, including Asia, Europe, North America, and the Arctic, and the results matched well with all the monitoring data, except those obtained at e-waste sites due to the unpredictable PBDE emissions at these sites. This study provided evidence that, the new developed steady-state-based equation is superior to the equilibrium-state-based equation that has been used in describing the G / P partitioning behavior in decades. We suggest that, the investigation on G / P partitioning behavior for PBDEs should be based on steady state, not equilibrium state, and equilibrium is just a special case of steady state when nonequilibrium factors can be ignored. We also believe that our new equation provides a useful tool for environmental scientists in both monitoring and modeling research on G / P partitioning for PBDEs and can be extended to predict G / P partitioning behavior for other SVOCs as well.
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Wang, Ya, Jingwen Chen, Xianhai Yang, Felichesmi Lyakurwa, Xuehua Li, and Xianliang Qiao. "In silico model for predicting soil organic carbon normalized sorption coefficient (KOC) of organic chemicals." Chemosphere 119 (January 2015): 438–44. http://dx.doi.org/10.1016/j.chemosphere.2014.07.007.
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Ahrens, Michael J., and Christopher W. Hickey. "Extractability of Polycyclic Aromatic Hydrocarbons in Sediments: A Matter of Association?" Australian Journal of Chemistry 56, no. 3 (2003): 193. http://dx.doi.org/10.1071/ch02208.
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Bioavailability and accumulation of sediment-bound polycyclic aromatic hydrocarbons (PAHs) by benthic biota are closely related to their extractability by water or mild aqueous solvents. Nevertheless, PAH accumulation by benthic organisms is sometimes considerably different from predictions based on an equilibrium partition coefficient KOC between water and bulk sedimentary organic carbon (OC). We present evidence that PAH extractability is strongly affected by the type of OC acting as a sorbent. We compared extractability of spiked [14C]fluoranthene from a variety of natural and man-made OC matrices, including bulk sediment organic carbon, peat moss, power plant fly ash, diesel soot, petroleum/natural gas soot, coal dust, and carbon black. Artificial sediments were prepared from glass beads amended with equal weight percentages (2%) of nine different types of OC. Amended sediments were spiked with [14C]fluoranthene and batch-extracted with seawater and 0.5% sodium dodecyl sulfate (SDS) after 65 and 12 h of equilibration, respectively. Fluoranthene extractability by seawater ranged between 0.03% and 0.9%, corresponding to a 50-fold variation of apparent KOC, and 0.03–18% for SDS. Correlation between seawater and SDS extraction efficiencies was weak, suggesting differences in the mechanism of solubilization. These results demonstrate that use of a single value of KOC to predict bioavailability of fluoranthene should be avoided, and that attempts to extrapolate PAH extractability from water-only extraction experiments to aqueous solutions containing surface-active dissolved organic carbon, such as the gut fluids of deposit feeding macrofauna, is very likely to lead to erroneous predictions.
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Sonon, Leticia S., and A. Paul Schwab. "Adsorption Characteristics of Atrazine and Alachlor in Kansas Soils." Weed Science 43, no. 3 (1995): 461–66. http://dx.doi.org/10.1017/s0043174500081479.
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The adsorption of atrazine and alachlor was studied on samples of three horizons from soils with different textures and organic carbon contents. Soils were equilibrated with five concentrations of atrazine and alachlor using batch techniques. Adsorption affinity for atrazine and alachlor was approximated by the Freundlich constant (Kf), distribution coefficient (Kd), and the normalizedKdbased on organic carbon (Koc). Adsorption was not significantly correlated with soil depth, clay content, or organic carbon. Atrazine adsorption was a linear function of equilibrium concentration for nearly all soil horizons but was nonlinear in most horizons for alachlor. The extent of atrazine adsorption was greater in all horizons of the fine-textured soils (Kd= 1.5 to 5.5) compared to coarse-textured soils (Kd= 0.40 to 0.87). The same general trends with texture were not apparent for alachlor. Conversion ofKdtoKocfailed to reduce the variability in the linear adsorption coefficient for atrazine and alachlor in the different soils of this study.
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Lodge, Keith B. "The measurement of the organic-carbon normalized partition coefficient, Koc, for dioxin from contaminated sediment." Advances in Environmental Research 7, no. 1 (2002): 147–56. http://dx.doi.org/10.1016/s1093-0191(01)00120-4.
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Tao, Shu, Haishan Piao, R. Dawson, Xiaoxia Lu, and Haiying Hu. "Estimation of Organic Carbon Normalized Sorption Coefficient (KOC) for Soils Using the Fragment Constant Method." Environmental Science & Technology 33, no. 16 (1999): 2719–25. http://dx.doi.org/10.1021/es980833d.
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Wang, Bin, Jingwen Chen, Xuehua Li, et al. "Estimation of Soil Organic Carbon Normalized Sorption Coefficient (Koc) Using Least Squares-Support Vector Machine." QSAR & Combinatorial Science 28, no. 5 (2009): 561–67. http://dx.doi.org/10.1002/qsar.200860065.
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Ahn, Jeonghyeon, Guiying Rao, and Eric Vejerano. "Partitioning of 1,2-dichlorobenzene onto organic and inorganic aerosols." Environmental Chemistry 18, no. 2 (2021): 61. http://dx.doi.org/10.1071/en21016.
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Environmental contextContaminants adsorbed in aerosols are transported and deposited effectively to the respiratory system compared to their vapours. Measuring the extremely low concentration of highly volatile contaminants contained in aerosols is challenging; hence assessing their adverse effects on environmental and human health is less understood. The measured concentrations of these contaminants are similar to less volatile chemicals sampled from diverse environmental aerosols, suggesting that their contribution cannot be neglected. AbstractVolatile organic compounds (VOCs) are not expected to partition onto aerosols because of their high vapour pressure. Studies on gas–aerosol partitioning of VOCs have been limited because of the challenge in discriminating the small mass fraction of the VOCs in the aerosol relative to that in the gas phase. Here, we developed a bench-scale system to investigate the partitioning of a surrogate VOC, 1,2-dichlorobenzene (1,2-DCB), into inorganic and organic aerosols under different relative humidities (RHs) and temperatures. The partitioning coefficient (Kip) of 1,2-DCB into succinic acid (SA) aerosol was ~10× higher than those into ammonium sulfate (Am Sulf) aerosol. These Kip corresponded to 0.23–3.27 pg 1,2-DCB µg−1 of SA aerosol and 0.02–3.82 pg 1,2-DCB µg−1 of Am Sulf aerosol for RH levels of 5–95%. Sorption of 1,2-DCB onto Am Sulf aerosol followed the classic relationship between Kip and RH, whereas that onto SA did not. For Am Sulf aerosols, RH levels exceeding 50% have a negligible effect on partitioning, in which the extremely low amount of 1,2-DCB partitioned into the aerosol via dissolution. The octanol–air partition (KOA) model predicted the Kip of 1,2-DCB for SA aerosol better than the saturated vapour pressure partition (Pi0) model, whereas the Pi0 model predicted Kip better than the KOA model only when absorptive partitioning was considered.
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Mutavdžić Pavlović, Dragana, Kristina Tolić Čop, Helena Prskalo, and Mislav Runje. "Influence of Organic Matter on the Sorption of Cefdinir, Memantine and Praziquantel on Different Soil and Sediment Samples." Molecules 27, no. 22 (2022): 8008. http://dx.doi.org/10.3390/molecules27228008.
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Pharmaceuticals are known for their great effects and applications in the treatment and suppression of various diseases in human and veterinary medicine. The development and modernization of science and technologies have led to a constant increase in the production and consumption of various classes of pharmaceuticals, so they pose a threat to the environment, which can be subjected to the sorption process on the solid phase. The efficiency of sorption is determined by various parameters, of which the physicochemical properties of the compound and the sorbent are very important. One of these parameters that determine pharmaceutical mobility in soil or sediment is the soil–water partition coefficient normalized to organic carbon (Koc), whose determination was the purpose of this study. The influence of organic matter, suspended in an aqueous solution of pharmaceutical (more precisely: cefdinir, memantine, and praziquantel), was studied for five different types of soil and sediment samples from Croatia. The linear, Freundlich, and Dubinin–Raduskevich sorption isotherms were used to determine specific constants such as the partition coefficient Kd, which directly describes the strength of sorbate and sorbent binding. The linear model proved to be the best with the highest correlation coefficients, R2 > 0.99. For all three pharmaceuticals, a positive correlation between sorption affinity described by Kd and Koc and the amount of organic matter was demonstrated.
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Shea, Patrick J. "Role of Humified Organic Matter in Herbicide Adsorption." Weed Technology 3, no. 1 (1989): 190–97. http://dx.doi.org/10.1017/s0890037x00031614.
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Organic matter is the soil constituent most often associated with herbicide adsorption. Structural diversity makes humified organic material an ideal substrate for the adsorption of many pesticides, but variability in composition and distribution in situ complicates interpretation of its quantitative effect on adsorption. Variability in the adsorption distribution coefficient (KD) of a herbicide among soils often is due to differences in organic matter content and can be reduced by adjusting KDfor soil organic carbon content and computing the organic carbon partition coefficient (Koc). Koccan be estimated from the octanol-water partition coefficient (Kow) of organic compounds, but the correlation weakens as compound polarity increases. Kocalso can be correlated with aqueous solubility if a correction is made for the melting point of compounds that are solids at 25 C. Relative adsorption can be estimated from parachor and molecular connectivity indices; but corrections are needed for polar compounds, and correlations with KDor Kochave been variable. Such predictive methods may be useful for broad classification purposes, but accurate extrapolation generally requires site-specific adsorption measurements. Empirical models which accommodate the multiple regression of organic matter content and other soil properties such as clay content, pH, and cation exchange capacity on herbicide adsorption can increase accuracy, but interpretation may be restricted to a small number of sites.
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Sarmah, Ajit K., Murray E. Close, Liping Pang, Robert Lee, and Steve R. Green. "Field study of pesticide leaching in a Himatangi sand (Manawatu) and a Kiripaka bouldery clay loam (Northland). 2. Simulation using LEACHM, HYDRUS-1D, GLEAMS, and SPASMO models." Soil Research 43, no. 4 (2005): 471. http://dx.doi.org/10.1071/sr04040.
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Abstract We applied 5 pesticides, along with bromide as a conservative tracer, at 2 field sites (Northland and Manawatu, North Island of New Zealand), and their distributions in the soil profile were monitored through soil core and suction cup sampling for 18 months. Field-measured values were simulated using LEACHM, HYDRUS-1D, GLEAMS, and SPASMO models and compared against the measured datasets at both these sites. All 4 models predicted the measured dataset for each of the compounds with reasonable degree of accuracy; however, some discrepancies were observed. Prediction by GLEAMS was by far the best, as indicated by the goodness of fit parameters. Pesticide leaching parameters, organic carbon partition coefficient (Koc), and degradation half-life (T1/2) were optimised using the PEST optimisation package. For diazinon and terbuthylazine the parameters obtained for each of the models were generally close to the literature range. However, Koc and T1/2 values for atrazine, hexazinone, and procymidone were found to be slightly lower than the available literature range data.
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Tao, Shu, and Xiaoxia Lu. "Estimation of organic carbon normalized sorption coefficient (Koc) for soils by topological indices and polarity factors." Chemosphere 39, no. 12 (1999): 2019–34. http://dx.doi.org/10.1016/s0045-6535(99)00091-0.
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Baskaran, Sivani, Ying Duan Lei, and Frank Wania. "A Database of Experimentally Derived and Estimated Octanol–Air Partition Ratios (KOA)." Journal of Physical and Chemical Reference Data 50, no. 4 (2021): 043101. http://dx.doi.org/10.1063/5.0059652.
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Equilibrium partition coefficients or partition ratios are a fundamental concept in physical chemistry, with wide applications in environmental chemistry. While comprehensive data compilations for the octanol–water partition ratio and the Henry’s law constant have existed for many years, no comparable effort for the octanol–air partition ratio ( KOA) exists. Considering the increasing use of KOA in understanding a chemical’s partitioning between a wide variety of organic phases (organic phases in atmospheric particles, plant foliage, polymeric sorbents, soil organic matter, animal tissues, etc.) and the gas phase, we have compiled all KOA values reported in the published literature. The dataset includes more than 2500 experimentally derived values and more than 10 000 estimated values for KOA, in total covering over 1500 distinct molecules. The range of measured log10 KOA values extends from −2 to 13. Many more measured values have been reported in the log10 KOA range from 2 to 5 and from 6 to 11 compared to the range from 5 to 6, which is due to the complementary applicability range of static and dynamic measurement techniques. The compilation also identifies measured data that are judged not reliable. KOA values for substances capable of undergoing strong hydrogen bonding derived from regressions with retention times on nonpolar gas chromatographic columns deviate strongly from values estimated by prediction techniques that account for such intermolecular interactions and should be considered suspect. It is hoped that the database will serve as a source for locating existing KOA data and for the calibration and evaluation of new KOA prediction techniques.
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Baskaran, Sivani, Ying Duan Lei, and Frank Wania. "A Database of Experimentally Derived and Estimated Octanol–Air Partition Ratios (KOA)." Journal of Physical and Chemical Reference Data 50, no. 4 (2021): 043101. http://dx.doi.org/10.1063/5.0059652.
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Equilibrium partition coefficients or partition ratios are a fundamental concept in physical chemistry, with wide applications in environmental chemistry. While comprehensive data compilations for the octanol–water partition ratio and the Henry’s law constant have existed for many years, no comparable effort for the octanol–air partition ratio ( KOA) exists. Considering the increasing use of KOA in understanding a chemical’s partitioning between a wide variety of organic phases (organic phases in atmospheric particles, plant foliage, polymeric sorbents, soil organic matter, animal tissues, etc.) and the gas phase, we have compiled all KOA values reported in the published literature. The dataset includes more than 2500 experimentally derived values and more than 10 000 estimated values for KOA, in total covering over 1500 distinct molecules. The range of measured log10 KOA values extends from −2 to 13. Many more measured values have been reported in the log10 KOA range from 2 to 5 and from 6 to 11 compared to the range from 5 to 6, which is due to the complementary applicability range of static and dynamic measurement techniques. The compilation also identifies measured data that are judged not reliable. KOA values for substances capable of undergoing strong hydrogen bonding derived from regressions with retention times on nonpolar gas chromatographic columns deviate strongly from values estimated by prediction techniques that account for such intermolecular interactions and should be considered suspect. It is hoped that the database will serve as a source for locating existing KOA data and for the calibration and evaluation of new KOA prediction techniques.
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Koudryashova, Yuliya, Tatiana Chizhova, Mutsuo Inoue, et al. "Deep Water PAH Cycling in the Japan Basin (the Sea of Japan)." Journal of Marine Science and Engineering 10, no. 12 (2022): 2015. http://dx.doi.org/10.3390/jmse10122015.
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A vertical pattern of fractionated polycyclic aromatic hydrocarbons (PAH) was studied in the Japan Basin in the Sea of Japan. The highest PAH concentration was found in the mesopelagic realm, possibly resulting from deep convection and/or subduction of intermediate water and its biogeochemical setting in the western Japan Basin. Using 226Ra and 228Ra as tracers revealed the PAH load in the open sea from the coastal polluted water. Dissolved PAHs (DPAH, fraction < 0.5 µm) were significantly prevalent particulate PAHs (PPAH, fraction > 0.5 µm) at all depths, associated with a predominance of dissolved organic carbon (DOC) over particulate organic carbon (POC). Hydrophobicity was more important for higher-molecular-weight PAHs to be distributed between particles and the solution, while the high Koc of low-molecular-weight PAHs indicated that their partitioning was driven by other factors, such as adsorbing of soot particles. PPAH and DPAH profiles differed from the POC and DOC profiles; nevertheless, a positive moderate correlation was found for DPAH and DOC for depths below the epipelagic, suggesting the similarity of the mechanisms of input of dissolved organic matter and DPAH into the deep interior of the Sea of Japan. The PAH flux calculations showed that biological pumps and overturning circulation contribute almost equally to removing PAHs from the bathypelagic waters of the Japan Basin.
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Schwarzenbach, R. P., and J. Westall. "Sorption of Hydrophobic Trace Organic Compounds in Groundwater Systems." Water Science and Technology 17, no. 9 (1985): 39–55. http://dx.doi.org/10.2166/wst.1985.0081.
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Factors influencing the subsurface sorption behavior of neutral and ionizable trace organic compounds are discussed. At equilibrium, the sorption of a neutral hydrophobic organic compound can be expressed by a simple partition coefficient. Partition coefficients, and thus retardation factors, may be estimated from the octanol/water partition coefficient of the compound and the organic carbon content of the aquifer material, if the organic carbon content exceeds 0.1%. For ionizable (anionic) hydrophobic compounds (represented by chlorinated phenols), the distribution ratio depends on both the pH and ionic strength of the aqueous phase, in contrast to the partitioning model for neutral compounds in which the composition of the aqueous phase is relatively unimportant.
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Zhu, Fu-Jie, Peng-Tuan Hu, and Wan-Li Ma. "A new steady-state gas–particle partitioning model of polycyclic aromatic hydrocarbons: implication for the influence of the particulate proportion in emissions." Atmospheric Chemistry and Physics 23, no. 15 (2023): 8583–90. http://dx.doi.org/10.5194/acp-23-8583-2023.
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Abstract. Gas–particle (G–P) partitioning is a crucial atmospheric process for semi-volatile organic compounds (SVOCs), particularly polycyclic aromatic hydrocarbons (PAHs). However, accurately predicting the G–P partitioning of PAHs has remained a challenge. In this study, we established a new steady-state G–P partitioning model based on the level-III multimedia fugacity model, with a particular focus on the particulate proportion (ϕ0) of PAHs in emissions. Similar to previous steady-state models, our new model divided the G–P partitioning behavior into three domains based on the threshold values of log KOA (octanol–air partitioning coefficient), with slopes of 1, from 1 to 0, and 0 for the three domains. However, our model differed significantly from previous models in different domains. We found that deviations from the equilibrium-state G–P partitioning models were caused by both gaseous interference and particulate interference, with ϕ0 determining the influence of this interference. Different forms of the new steady-state model were observed under different values of ϕ0, highlighting its significant impact on the G–P partitioning of PAHs. Comparison of the G–P partitioning of PAHs between the prediction results of our new steady-state model and monitored results from 11 cities in China suggested varying prediction performances under different values of ϕ0, with the lowest root mean square error observed when ϕ0 was set to 0.9 or 0.99. The results indicated that the ϕ0 was a crucial factor for the G–P partitioning of PAHs. Furthermore, our new steady-state model also demonstrated excellent performance in predicting the G–P partitioning of PAHs with entirely gaseous emission and polybrominated diphenyl ethers with entirely particulate emission. Therefore, we concluded that the ϕ0 should be considered in the study of G–P partitioning of PAHs, which also provided a new insight into other SVOCs.
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Amano, K., and T. Fukushima. "Partitioning of a Surfactant Between Lake Water, Suspended Solids and Sediment." Water Science and Technology 26, no. 9-11 (1992): 2571–74. http://dx.doi.org/10.2166/wst.1992.0790.
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The partitioning of linear alkylbenzenesulfonates (LAS) between solution and adsorbed phases and the factors of the partitioning are summarized herein based on the field observation and the adsorption experiment. All adsorption experiments using suspended solids and sediment solids taken from Lake Teganuma were performed between 0.2 and 6 mg l−1 of the initial LAS concentrations. The relationships between the partition coefficient of LAS and two factors of solid concentration in the water and the fractional organic carbon content of solid were confirmed. Based on our experimental results, it was expected that the partition coefficient of LAS in the natural water or sediment could be estimated by an empirical model, and this model was verified by using the adsorption data from field observations. A reasonable agreement between the observed and the predicted partition coefficient was obtained (correlation coefficient was between 0.48 and 0.83).
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Mervosh, Todd L. "Sorption of the Herbicides Isoxaben and Oryzalin to Soils and Container Media." Journal of Environmental Horticulture 21, no. 1 (2003): 11–15. http://dx.doi.org/10.24266/0738-2898-21.1.11.
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Abstract The herbicides isoxaben (Gallery) and oryzalin (Surflan) are commonly used to prevent weed emergence around ornamental plants in nurseries and landscapes. Saturated batch experiments were conducted in the laboratory to generate equilibrium sorption isotherms for these herbicides in soils and container media. Soils consisted of [A] a sandy loam containing 1.24% organic matter (by wt) after sieving, and [B] a silt loam containing 1.36% organic matter (by wt) after sieving. Container media obtained from nurseries consisted of [C] a mixture of 50% peat and 50% sand (by vol) containing 18.5% organic matter (by wt) after sieving, and [D] a mixture of 70% bark, 25% peat, and 5% fine stone (by vol) containing 34.9% organic matter (by wt) after sieving. Sorption isotherms were generated from these data. Based on sorption coefficients (Kd, Kf), container mix D sorbed both herbicides to a much greater extent than did the other substrates. Oryzalin sorption was greater than isoxaben sorption in each soil and container mix. For oryzalin, organic carbon partition coefficient (Koc) values in the soils were greater than those in the container mixes. Compositional differences in organic matter between soils and container media may account for differences in herbicide sorption in these media.
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Just, AC, DW Hawker, and DW Connell. "Partitioning of Lindane between sediment, water and the Crustacean Metapenaeus macleayi." Marine and Freshwater Research 41, no. 3 (1990): 389. http://dx.doi.org/10.1071/mf9900389.
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The partitioning behaviour of lindane between sediment, water and the prawn Metapenaeus macleayi was investigated. The sediment-to-water partition coefficient was determined with sealed glass vials in laboratory experiments and found to be 9.52, or 2164 on an organic carbon basis. This is in agreement with relevant literature data and confirms that the organic matter of the sediment is the primary sorption site in this process. The bioconcentration factor was evaluated from laboratory experiments with prawns in sealed glass jars in which the lindane seawater solution was changed frequently. Under these conditions, effective equilibrium was attained after 24 h. Measured uptake (k1) and clearance (k2) rate constants were smaller than predicted on the basis of existing general relationships between k1, k2 and the octanol/water partition coefficient (Kow) for crustaceans. The bioconcentration factor (KB) was found to be 5.50, or 1273 on a lipid basis, which is also smaller than values estimated from general relationships. The sediment-to-prawn bioaccumulation factor was 0.58, which means that biotic concentrations will be significantly less than those observed in sediments.
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Pollock, Daniel, Ramsis Salama, and Rai Kookana. "A study of atrazine transport through a soil profile on the Gnangara Mound, Western Australia, using LEACHP and Monte Carlo techniques." Soil Research 40, no. 3 (2002): 455. http://dx.doi.org/10.1071/sr01043.
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A preliminary risk assessment of atrazine leaching at a strawberry farm on the Gnangara Mound, Western Australia, was performed using LEACHP in conjunction with Monte Carlo techniques. Monte Carlo techniques were also used to implement a sensitivity analysis of LEACHP to determine influential parameters. As an extension to the sensitivity analysis, a model comparison was performed with similar models, in order to quantify differences arising from the use of different models. The Monte Carlo risk assessment involved simultaneous variation of LEACHP's soil parameters and selected chemical parameters to assess the risk of atrazine leaching past the root-zone at the experimental site. This Monte Carlo risk assessment predicted that of the 100 mg/m2 of atrazine applied at the experimental site, the mean cumulative mass per unit area of atrazine to leach below the root-zone after 263 days was 49 mg/m2, with a standard deviation of 4.1 and a range from 37 to 62 mg/m2. The Monte Carlo sensitivity analysis of LEACHP tested selected soil and chemical parameters, one at a time, to determine the influence of each parameter on the models predictions of cumulative mass per unit area of atrazine to leach below the root-zone. The chemical parameters organic carbon partition coefficient (Koc) and degradation rate constants were found to be more influential than the soil parameters, with Koc being the most influential parameter. The most influential of the soil parameters was organic carbon content, followed by bulk density. The model comparison involved 4 separate simulations: LEACHP using Richards' equation (LEACHP (Richards)), LEACHP using Addiscott's model of water and solute movement (LEACHP (Addiscott), MACRODB, and GLEAMS. The results from this exercise showed that LEACHP (Richards) and MACRODB made similar predictions for the cumulative mass per unit area of atrazine to leach below the root-zone (49 and 50 mg/m2, respectively), while GLEAMS and LEACHP (Addiscott) made significantly lower predictions (35 and 38 mg/m2, respectively). The results from this study indicate there is a significant risk of atrazine leaching at the experimental site; however, more detailed field measurements and further modelling would enable more accurate predictions.
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Li, Jingyi, Haowen Zhang, Qi Ying, et al. "Impacts of water partitioning and polarity of organic compounds on secondary organic aerosol over eastern China." Atmospheric Chemistry and Physics 20, no. 12 (2020): 7291–306. http://dx.doi.org/10.5194/acp-20-7291-2020.
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Abstract. Secondary organic aerosol (SOA) is an important component of fine particular matter (PM2.5). Most air quality models use an equilibrium partitioning method along with the saturation vapor pressure (SVP) of semivolatile organic compounds (SVOCs) to predict SOA formation. However, the models typically assume that the organic particulate matter (OPM) is an ideal mixture and ignore the partitioning of water vapor to OPM. In this study, the Community Multiscale Air Quality model (CMAQ) is updated to investigate the impacts of water vapor partitioning and nonideality of the organic–water mixture on SOA formation during winter (January) and summer (July) of 2013 over eastern China. The updated model treats the partitioning of water vapor molecules into OPM and uses the universal functional activity coefficient (UNIFAC) model to estimate the activity coefficients of species in the organic–water mixture. The modified model can generally capture the observed surface organic carbon (OC) with a correlation coefficient R of 0.7 and the surface organic aerosol (OA) with the mean fractional bias (MFB) and mean fractional error (MFE) of −0.28 and 0.54, respectively. SOA concentration shows significant seasonal and spatial variations, with high concentrations in the North China Plain (NCP), central China, and the Sichuan Basin (SCB) regions during winter (up to 25 µg m−3) and in the Yangtze River Delta (YRD) during summer (up to 16 µg m−3). In winter, SOA decreases slightly in the updated model, with a monthly averaged relative change of 10 %–20 % in the highly concentrated areas, mainly due to organic–water interactions. The monthly averaged concentration of SOA increases greatly in summer, by 20 %–50 % at the surface and 30 %–60 % in the whole column. The increase in SOA is mainly due to the increase in biogenic SOA in inland areas and anthropogenic SOA in coastal areas. As a result, the averaged aerosol optical depth (AOD) is increased by up to 10 %, and the cooling effect of aerosol radiative forcing (ARF) is enhanced by up to 15 % over the YRD in summer. The aerosol liquid water content associated with OPM (ALWorg) at the surface is relatively high in inland areas in winter and over the ocean in summer, with a monthly averaged concentration of 0.5–3.0 and 5–7 µg m−3, respectively. The hygroscopicity parameter κ of OA based on the κ–Köhler theory is determined using the modeled ALWorg. The correlation of κ with the O:C ratio varies significantly across different cities and seasons. Analysis of two representative cities, Jinan (in the NCP) and Nanjing (in the YRD), shows that the impacts of water partitioning and nonideality of the organic–water mixture on SOA are sensitive to temperature, relative humidity (RH), and the SVP of SVOCs. The two processes exhibit opposite impacts on SOA in eastern China. Water uptake increases SOA by up to 80 % in the organic phase, while including nonunity activity coefficients decreases SOA by up to 50 %. Our results indicate that both water partitioning into OPM and the activity coefficients of the condensed organics should be considered in simulating SOA formation from gas–particle partitioning, especially in hot and humid environments.
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Wu, Qiang, Siqi Cao, Zhenyi Chen, Xiaoxuan Wei, Guangcai Ma, and Haiying Yu. "Predictive Models of Gas/Particulate Partition Coefficients (KP) for Polycyclic Aromatic Hydrocarbons and Their Oxygen/Nitrogen Derivatives." Molecules 27, no. 21 (2022): 7608. http://dx.doi.org/10.3390/molecules27217608.
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Polycyclic aromatic hydrocarbons (PAHs) and their oxygen/nitrogen derivatives released into the atmosphere can alternate between a gas phase and a particulate phase, further affecting their environmental behavior and fate. The gas/particulate partition coefficient (KP) is generally used to characterize such partitioning equilibrium. In this study, the correlation between log KP of fifty PAH derivatives and their n-octanol/air partition coefficient (log KOA) was first analyzed, yielding a strong linear correlation (R2 = 0.801). Then, Gaussian 09 software was used to calculate quantum chemical descriptors of all chemicals at M062X/6-311+G (d,p) level. Both stepwise multiple linear regression (MLR) and support vector machine (SVM) methods were used to develop the quantitative structure-property relationship (QSPR) prediction models of log KP. They yield better statistical performance (R2 > 0.847, RMSE < 0.584) than the log KOA model. Simulation external validation and cross validation were further used to characterize the fitting performance, predictive ability, and robustness of the models. The mechanism analysis shows intermolecular dispersion interaction and hydrogen bonding as the main factors to dominate the distribution of PAH derivatives between the gas phase and particulate phase. The developed models can be used to predict log KP values of other PAH derivatives in the application domain, providing basic data for their ecological risk assessment.
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Jang, Yoonmi, Yongju Choi, and Kibeum Kim. "Changes in Adsorption Characteristics of Heavy Metals and Organic Pollutants Following Pyrolytic Treatment of Petroleum-Contaminated Dredged Sediment." Journal of Korean Society of Environmental Engineers 43, no. 7 (2021): 513–23. http://dx.doi.org/10.4491/ksee.2021.43.7.513.
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Objectives : This study investigated the changes in adsorption characteristics of dredged sediment for heavy metals and organic pollutants after petroleum contamination followed by pyrolytic treatment.Methods : Pyrolytic treatment was conducted at two heating temperatures, 300℃ and 500℃, for 30 min using muffle furnace. Sediment spiked with No. 6 Fuel Oil at initial total petroleum hydrocarbon (TPH) concentrations of 5,000-50,000 mg/kg was used. Sorption experiments were conducted for heavy metals (Cd, Cu, Pb, Zn, Ni, Hg, As, Cr), phenanthrene and bisphenol A using clean sediment (sediment before the petroleum spiking) and pyrolyzed sediment.Results and Discussion : Pyrolytic treatment at 500℃ showed excellent TPH removal efficiency, resulting in the residual concentration of less than 50 mg/kg for all initial TPH contamination levels. High efficiencies (> 98%) were observed for the sorptive removal of Cu, Zn and Pb in the aqueous phase for both the two sediments. The removal efficiencies of Ni and Cd from the aqueous phase using pyrolyzed sediment were 31% and 24% lower than those using clean sediment, respectively, due to the reduced oxygen-containing functional group content and specific surface area after the pyrolytic treatment. The sediment-water distribution coefficient (Kd) and sediment organic carbon-water distribution coefficient (Koc) values of bisphenol A and phenanthrene in pyrolyzed sediment were considerably higher than in clean sediment due to the high organic compound sorption affinity exhibited by carbonaceous matter that was generated during the pyrolytic sediment treatment.Conclusions : The capability of pyrolytic treatment of dredged sediment to notably improve its organic compound sorption capacity may be exploited for beneficial use of the treatment product. The product may be applied as fill and backfill, soil amendment, or in-situ sediment capping materials in highly industrialized areas where mitigation measures for organic contaminant migration are necessary.
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Ilyas, Huma, Ilyas Masih, and Eric D. van Hullebusch. "Pharmaceuticals' removal by constructed wetlands: a critical evaluation and meta-analysis on performance, risk reduction, and role of physicochemical properties on removal mechanisms." Journal of Water and Health 18, no. 3 (2020): 253–91. http://dx.doi.org/10.2166/wh.2020.213.
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Abstract This paper presents a comprehensive and critical analysis of the removal of pharmaceuticals (PhCs), the governing physicochemical properties, and removal mechanisms in constructed wetlands (CWs). The average removal efficiency of the most widely studied 34 PhCs ranges from 21% to 93%, with the exception of one PhC that exhibited negative removal. Moreover, CWs are effective in significantly reducing the environmental risk caused by many PhCs. Based on risk assessment, 12 PhCs were classified under high risk category (oxytetracycline &gt; ofloxacin &gt; sulfamethoxazole &gt; erythromycin &gt; sulfadiazine &gt; gemfibrozil &gt; ibuprofen &gt; acetaminophen &gt; salicylic acid &gt; sulfamethazine &gt; naproxen &gt; clarithromycin), which could be considered for regular monitoring, water quality standard formulation and control purposes. Biodegradation (aerobic and anaerobic) is responsible for the removal of the majority of PhCs, often in conjunction with other mechanisms (e.g., adsorption/sorption, plant uptake, and photodegradation). The physicochemical properties of molecules play a pivotal role in the elimination processes, and could serve as important predictors of removal. The correlation and multiple linear regression analysis suggest that organic carbon sorption coefficient (Log Koc), octanol-water distribution coefficient (Log Dow), and molecular weight form a good predictive linear regression model for the removal efficiency of PhCs (R2 = 0.65, P-value &lt;0.05).
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Zhu, Fu-Jie, Zi-Feng Zhang, Li-Yan Liu, et al. "The impact of gaseous degradation on the gas–particle partitioning of methylated polycyclic aromatic hydrocarbons." Atmospheric Chemistry and Physics 24, no. 10 (2024): 6095–103. http://dx.doi.org/10.5194/acp-24-6095-2024.
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Abstract. The partitioning of semi-volatile organic compounds (SVOCs) between gas and particle phases plays a crucial role in their long-range transport and health risk assessment. However, the accurate prediction of the gas–particle (G–P) partitioning quotient (KP′) remains a challenge, especially for the light-molecular-weight (LMW) SVOCs due to their upward deviation from equilibrium state. In this study, the phenomenon with the influence of gaseous degradation on G–P partitioning was observed. Based on the diurnal study of concentrations and KP′ values for methylated polycyclic aromatic hydrocarbons (Me-PAHs), it was found that the KP′ values of methylated naphthalenes (Me-Naps; one type of LMW SVOC) during the daytime were higher than during the nighttime, and the regression lines of log KP′ versus log KOA (octanol–air partitioning coefficient) for daytime and nighttime were non-overlapping, which were different from other Me-PAHs. Compared with other diurnal influencing factors, the higher gaseous degradation of Me-Naps in the daytime than in the nighttime should partially explain their special diurnal variation in KP′, which provided a new explanation for the non-equilibrium behavior of KP′ for LMW SVOCs. Moreover, the influence of gaseous degradation on the deviation of KP′ from equilibrium state was deeply studied based on the steady-state G–P partitioning model considering particulate proportion in emission (ϕ0). The increasing times of KP′ influenced by the gaseous degradation deviated from equilibrium state can be calculated by 1 + 13.2ϕ0 × kdeg (kdeg, gaseous degradation rate). The increase in KP′ along with the increase in kdeg proved that higher gaseous degradation in the daytime could increase the KP′ value. Furthermore, an amplification in KP′ ranging from 1.11 to 5.58 times (90 % confidence interval: 1.01 to 14.4) under different ϕ0 values (0 to 1) in the temperature range of −50 to 50 °C was estimated by the Monte Carlo analysis. In summary, it can be concluded that the influence of gaseous degradation should also be considered in the G–P partitioning models of SVOCs, especially for the LMW SVOCs, which provided new insights into the related fields.
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Jung, Hae Ryong, Sang Deok Seo, and Hee Chul Choi. "Preparation of Mesostructured Carbon (MSC) for Removal of Natural Organic Matter (NOM) in Aqueous Solution." Materials Science Forum 544-545 (May 2007): 123–26. http://dx.doi.org/10.4028/www.scientific.net/msf.544-545.123.
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Mesostructured carbon (MSC) has been synthesized by the carbonization of assynthesized mesocellular siliceous foam (MCF)/P123 nanocomposite followed by the dissolution of the silica using 10 wt.% HF solution. SEM, TEM, and BET instruments were used to characterize the mesostructured carbon. Batch experiments were performed to evaluate its ability to adsorb natural organic matter (NOM) in various pH levels. MSC showed enhanced adsorption capacity for NOM than the commercial activated carbons. MSC possessed approximately 3.3 and 2.2 times greater the solid-water partitioning coefficient of NOM, Kd, at pH 7 than coal-based and coconutbased activated carbons, respectively. This increased Kd of MSC resulted from mesoporous structures in the range of 4-6 nm on the surface. The Kd value decreased with increasing initial pH levels, which is considered to be due to ionization of functional groups of NOM.
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Howell, Nathan L., and Hanadi S. Rifai. "PCDD/F and PCB water column partitioning examination using natural organic matter and black carbon partition coefficient models." Environmental Science and Pollution Research 23, no. 7 (2015): 6322–33. http://dx.doi.org/10.1007/s11356-015-5802-y.
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Müller, M. N., M. Lebrato, U. Riebesell, et al. "Influence of temperature and CO<sub>2</sub> on the strontium and magnesium composition of coccolithophore calcite." Biogeosciences Discussions 10, no. 10 (2013): 15559–86. http://dx.doi.org/10.5194/bgd-10-15559-2013.
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Abstract. Marine calcareous sediments provide a fundamental basis for paleoceanographic studies aiming to reconstruct past oceanic conditions and understand key biogeochemical element cycles. Calcifying unicellular phytoplankton (coccolithophores) are a major contributor to both carbon and calcium cycling by photosynthesis and the production of calcite (coccoliths) in the euphotic zone and the subsequent long-term deposition and burial into marine sediments. Here we present data from controlled laboratory experiments on four coccolithophore species and elucidate the relation between the divalent cation (Sr, Mg and Ca) partitioning in coccoliths and cellular physiology (growth, calcification and photosynthesis). Coccolithophores were cultured under different seawater temperature and carbonate chemistry conditions. The partition coefficient of strontium (DSr) was positively correlated with both carbon dioxide (pCO2) and temperature but displayed no coherent relation to particulate organic and inorganic carbon production rates. Furthermore, DSr correlated positively with cellular growth rates when driven by temperature but no correlation was present when changes in growth rates were pCO2-induced. The results demonstrate the complex interaction between environmental forcing and physiological control on the strontium partitioning in coccolithophore calcite. The partition coefficient of magnesium (DMg) displayed species-specific differences and elevated values under nutrient limitation. No conclusive correlation between coccolith DMg and temperature was observed but pCO2 induced a rising trend in coccolith DMg. Interestingly, the best correlation was found between coccolith DMg and chlorophyll a production suggesting that chlorophyll a and calcite associated Mg originate from the same intracellular pool. These results give an extended insight into the driving factors that lead to variations in the coccolith Mg / Ca ratio and can be used for Sr / Ca and Mg / Ca paleoproxy calibration.
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Abiven, David, Stéphanie Boudesocque, Emmanuel Guillon, Michel Couderchet, Jacques Dumonceau, and Michel Aplincourt. "Sorption of the Herbicide Terbumeton and its Metabolites onto Soils. Influence of Copper(II)." Environmental Chemistry 3, no. 1 (2006): 53. http://dx.doi.org/10.1071/en05060.
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Environmental Context.Agrochemicals have contributed greatly to modern agriculture, allowing better yields and lower costs. However, their extensive use has led to frequent contamination of underground and surface water. A better knowledge of the fate of pesticides from the sprayer to the water that would take into account the diversity of the physical and chemical properties of the various molecules and environmental conditions should help in the challenge of protecting and restoring natural water quality. Abstract.The intensive use of terbumeton (N-(1,1-dimethyl)-N′-ethyl-6-methoxy-1,3,5-triazine-2,4-diamine) has resulted in its widespread presence, together with its main metabolites, in surface- and groundwater. To estimate the fate of these compounds, their adsorption and desorption properties were studied in vineyard soils. The values of the organic carbon normalized adsorption coefficient (KOC) for terbumeton (34.6 and 39.2 L g−1) were significantly higher than those of its metabolites (between 6.8 and 21.1 L g−1). Terbumeton exhibited a higher adsorption capacity and a lower desorption potential as compared with the metabolites. An important hysteresis was observed in all cases. The Freundlich isotherms exhibited a linear shape, which was interpreted as non-specific interaction. The influence of copper(II), a ubiquitous metal cation in vineyard soils, on pesticide sorption was also studied. Copper significantly decreased the amount of adsorbed terbumeton when present in a high concentration (2 ×10−4 M).
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Navarro, Irene, Adrián de la Torre, Paloma Sanz, Miguel Ángel Porcel, Gregoria Carbonell, and María de los Ángeles Martínez. "Transfer of perfluorooctanesulfonate (PFOS), decabrominated diphenyl ether (BDE-209) and Dechlorane Plus (DP) from biosolid-amended soils to leachate and runoff water." Environmental Chemistry 15, no. 4 (2018): 195. http://dx.doi.org/10.1071/en18032.
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Environmental contextThe potential of pollutants to migrate from biosolids must be considered when assessing the environmental risk associated with the application of biosolids in agriculture. We conducted semi-field tests simulating natural conditions to determine the leaching and runoff capacity of emerging organic contaminants following fortification and application of municipal biosolids. We demonstrate the transfer of pollutants from biosolid-amended soil to leachate and runoff water generated by natural rainfall. AbstractAnthropogenic perfluoroalkyl substances, PFASs, and halogenated flame retardants, HFRs, have been detected in different environmental compartments. In order to determine the fate of these compounds in the soil–water system, a semi-field simulated runoff experiment was conducted following the application of municipal organic waste. Therefore, the application of four biosolids was carried out. The biosolids were fortified with perfluorooctanesulfonate (PFOS; ~1 mg PFOS per kg biosolid), decabromodiphenyl ether (c-decaBDE; ~10 mg kg−1) and Dechlorane Plus (DP; ~0.26 mg kg−1) commercial mixtures and were applied to soil packed in 15 runoff-leaching trays (2.5 × 2 × 0.05 m). These trays were designed to collect the leachate and runoff water generated by natural rainfall. PFASs and HFRs were detected in leachate and runoff water from several rainfall events from November 2011 to May 2012 (a first rainfall event of 10.5 × 10−3 m, a second event of 16.0 × 10−3 m and a third pool event with a cumulative amount of 113.1 × 10−3 m) occurring after the initial biosolid application. The total mass distribution calculated in water samples showed a higher content in runoff samples (PFOS, 91 ± 2 %; BDE-209, 76 ± 17 %; DP, 83 ± 14 %). The order of the loamy sand soil affinity for PFOS, BDE-209 and DP was as follows: PFOS < BDE-209 ≤ DP, which was predicted, either from the compounds’ water solubility, the octanol-water partition coefficient (Kow) or the organic carbon-water partition coefficient (Koc). The calculated leaching potential (Lp) index or the Groundwater Ubiquity Score (GUS), which are based on these Kocs, revealed the reverse order of potential transport to surface and groundwater respectively.
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Radonic, Jelena, Dubravko Culibrk, Mirjana Vojinovic-Miloradov, Branislav Kukic, and Maja Turk-Sekulic. "Prediction of gas-particle partitioning of PAHs based on M5’ model trees." Thermal Science 15, no. 1 (2011): 105–14. http://dx.doi.org/10.2298/tsci100809005r.
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During the thermal combustion processes of carbon-enriched organic compounds, emission of polycyclic aromatic hydrocarbons into ambient air occurs. Previous studies of atmospheric distribution of polycyclic aromatic hydrocarbons showed low correlation between the experimental values and Junge-Pankow theoretical adsorption model, suggesting that other approaches should be used to describe the partitioning phenomena. The paper evaluates the applicability of multivariate piece-wise-linear M5? model-tree models to the problem of gas-particle partitioning. Experimental values of particle-associated fraction, obtained for 129 ambient air samples collected at 24 background, urban and industrial sites, were compared to the prediction results obtained using M5? and the Junge-Pankow model. The M5? approach proposed and models learned are able to achieve good correlation (correlation coefficient >0.9) for some low-molecular-weight compounds, when the target is to predict the concentration of gas phase based on the particle-associated phase. When converted to particle-bound fraction values, the results, for selected compounds, are superior to those obtained by Junge-Pankow model by several orders of magnitude, in terms of the prediction error.
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Wang, Zhe, Jiang Li, Li Lu, Jianwen Cao, Liangjie Zhao, and Song Luan. "Source, Partition and Ecological Risk of Polycyclic Aromatic Hydrocarbons in Karst Underground River Environment, Southern China." Water 13, no. 19 (2021): 2655. http://dx.doi.org/10.3390/w13192655.
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As the main source of drinking water in the karst areas of southern China, underground rivers play an important supporting role in local economic and social development. However, due to the special aquifer structure in the karst areas of southern China, polycyclic aromatic hydrocarbons (PAHs) can easily enter the water environment of underground rivers and cause serious pollution, which will affect the water quality safety. In this study, Qing-shui Spring underground river in Nanning city was selected as a representative of the typical underground river in southern China, and the pollution characteristics, source analysis, ecological risk assessment and diffusion law of PAHs were studied. The results showed that the total concentration of PAHs in groundwater and surface sediments was in the range of 282.42–464.88 ng/L and 400.14–1194.69 ng/g, respectively, and the overall concentrations of PAHs were below the moderate pollution level. Pollutant discharge and physical and chemical properties of PAHs caused the concentrations of PAHs to decrease gradually from upstream to downstream, but the proportion of high-cyclic PAHs increased gradually. According to the source analysis results of the ratio method, PAHs sources in groundwater were mainly biomass combustion sources in the upstream, oil sources in the middle and mixed sources in the downstream. Sediment and groundwater had some differences. The middle and upper reaches were the source of biomass combustion, while the middle and lower reaches were the mixed source. The ecological risk assessment results showed that the ecological risk of groundwater was at a moderate level, while the ecological risk of sediment was at a low level. Benzo[a]anthracene (BaA) and benzo[b]fluoranthene (BbF) in groundwater and acenaphthylene (Acy) and fluoranthene (Flu) in sediment should be monitored intensively. Appropriate control measures should be put in place to prevent further pollution. Partition coefficients varied from 0.73 to 3.85 L/g in the sediment–water interface, increasing with the rise of PAH compounds. All of the organic carbon partition coefficients (Koc) in the sediment–water interface were higher than predicate values based on the typical model of equilibrium distribution; this indicated that PAHs were strongly adsorbed in the sediment. The linear free energy relationship coefficient between the Koc value and the n-octanol-water partition coefficient (Kow) was 0.85 but the slope was lower than 1, indicating that sediment in the Qing-shui Spring underground river had weak lipophilic characteristics and adsorption ability for PAHs. The results can provide a reference for the risk assessment and pollution control of PAHs in the karst underground rivers in South China.
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Burton, Edward D., Ian R. Phillips, Darryl W. Hawker, and Dane T. Lamb. "Copper behaviour in a Podosol. 2. Sorption reversibility, geochemical partitioning, and column leaching." Soil Research 43, no. 4 (2005): 503. http://dx.doi.org/10.1071/sr04118.
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The sorption–desorption and leaching behaviour of Cu in a Podosol from south-east Queensland, Australia, was examined. Copper sorption was described by a linear distribution coefficient at low sorption levels (KDCa→0) of 481 L/kg and a sorption capacity (CS,Max) of 382 mg/kg. Selective removal of soil organic matter reduced these values by approximately 95%, indicating that Cu was sorbed predominantly to soil organic matter. The KDCa→0 and CS,Max values from Cu desorption experiments were 934 L/kg and 516 mg/kg, respectively, which indicates that sorption was not fully reversible. This irreversibility was related to aqueous Cu speciation (modelled with MINTEQA2), showing that aqueous complexes between Cu and dissolved organic carbon (DOC) comprised 28.3–72.8% and 21.3–45.4% of aqueous Cu in the sorption and desorption experiment, respectively. Sorption irreversibility was not evident when the corresponding data was presented as free Cu2+ isotherms. Both sorption and desorption experiments with free Cu2+ <0.2 mg/L were described by a KDCa→0 value of approximately 3000 L/kg. Sequential extraction of sorbed Cu indicated that at low concentrations, sorption occurred primarily via specific interactions, with non-specific sorption becoming increasing important at higher concentrations. Desorption of Cu in a column leaching experiment was attributable to exchange of sorbed Cu2+ with Na+. Leaching with a DOC solution of pH 7 and 135 mg/L greatly enhanced Cu mobility due to the formation of aqueous Cu–DOC complexes.
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Lumiaro, Emma, Milica Todorović, Theo Kurten, Hanna Vehkamäki, and Patrick Rinke. "Predicting gas–particle partitioning coefficients of atmospheric molecules with machine learning." Atmospheric Chemistry and Physics 21, no. 17 (2021): 13227–46. http://dx.doi.org/10.5194/acp-21-13227-2021.
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Abstract. The formation, properties, and lifetime of secondary organic aerosols in the atmosphere are largely determined by gas–particle partitioning coefficients of the participating organic vapours. Since these coefficients are often difficult to measure and to compute, we developed a machine learning model to predict them given molecular structure as input. Our data-driven approach is based on the dataset by Wang et al. (2017), who computed the partitioning coefficients and saturation vapour pressures of 3414 atmospheric oxidation products from the Master Chemical Mechanism using the COSMOtherm programme. We trained a kernel ridge regression (KRR) machine learning model on the saturation vapour pressure (Psat) and on two equilibrium partitioning coefficients: between a water-insoluble organic matter phase and the gas phase (KWIOM/G) and between an infinitely dilute solution with pure water and the gas phase (KW/G). For the input representation of the atomic structure of each organic molecule to the machine, we tested different descriptors. We find that the many-body tensor representation (MBTR) works best for our application, but the topological fingerprint (TopFP) approach is almost as good and computationally cheaper to evaluate. Our best machine learning model (KRR with a Gaussian kernel + MBTR) predicts Psat and KWIOM/G to within 0.3 logarithmic units and KW/G to within 0.4 logarithmic units of the original COSMOtherm calculations. This is equal to or better than the typical accuracy of COSMOtherm predictions compared to experimental data (where available). We then applied our machine learning model to a dataset of 35 383 molecules that we generated based on a carbon-10 backbone functionalized with zero to six carboxyl, carbonyl, or hydroxyl groups to evaluate its performance for polyfunctional compounds with potentially low Psat. The resulting saturation vapour pressure and partitioning coefficient distributions were physico-chemically reasonable, for example, in terms of the average effects of the addition of single functional groups. The volatility predictions for the most highly oxidized compounds were in qualitative agreement with experimentally inferred volatilities of, for example, α-pinene oxidation products with as yet unknown structures but similar elemental compositions.