Academic literature on the topic 'Typical gray soils'

AbstractApproaches for the collection and analysis of plastic debris in environmental matrices are rapidly evolving. Such plastics span a continuum of sizes, encompassing large (macro-), medium (micro-, typically defined as particles between 1 μm and 5 mm), and smaller (nano-) plastics. All are of environmental relevance. Particle sizes are dynamic. Large plastics may fragment over time, while smaller particles may agglomerate in the field. The diverse morphologies (fragment, fiber, sphere) and chemical compositions of microplastics further complicate their characterization. Fibers are of growing interest and present particular analytical challenges due to their narrow profiles. Compositional classes of emerging concern include tire wear, paint chips, semisynthetics (e.g., rayon), and bioplastics. Plastics commonly contain chemical additives and fillers, which may alter their toxicological potency, behavior (e.g., buoyancy), or detector response (e.g., yield fluorescence) during analysis. Field sampling methods often focus on >20 μm and even >300 μm sized particles and will thus not capture smaller microplastics (which may be most abundant and bioavailable). Analysis of a limited subgroup (selected polymer types, particle sizes, or shapes) of microplastics, while often operationally necessary, can result in an underestimation of actual sample content. These shortcomings complicate calls for toxicological studies of microplastics to be based on “environmentally relevant concentrations.” Sample matrices of interest include water (including wastewater, ice, snow), sediment (soil, dust, wastewater sludge), air, and biota. Properties of the environment, and of the particles themselves, may concentrate plastic debris in select zones (e.g., gyres, shorelines, polar ice, wastewater sludge). Sampling designs should consider such patchy distributions. Episodic releases due to weather and anthropogenic discharges should also be considered. While water grab samples and sieving are commonplace, novel techniques for microplastic isolation, such as continuous flow centrifugation, show promise. The abundance of nonplastic particulates (e.g., clay, detritus, biological material) in samples interferes with microplastic detection and characterization. Their removal is typically accomplished using a combination of gravity separation and oxidative digestion (including strong bases, peroxide, enzymes); unfortunately, aggressive treatments may damage more labile plastics. Microscope-based infrared or Raman detection is often applied to provide polymer chemistry and morphological data for individual microplastic particles. However, the sheer number of particles in many samples presents logistical hurdles. In response, instruments have been developed that employ detector arrays and rapid scanning lasers. The addition of dyes to stain particulates may facilitate spectroscopic detection of some polymer types. Most researchers provide microplastic data in the form of the abundances of polymer types within particle size, polymer, and morphology classes. Polymer mass data in samples remain rare but are essential to elucidating fate. Rather than characterizing individual particles in samples, solvent extraction (following initial sample prep, such as sediment size class sorting), combined with techniques such as thermoanalysis (e.g., pyrolysis), has been used to generate microplastic mass data. However, this may obviate the acquisition of individual particle morphology and compositional information. Alternatively, some techniques (e.g., electron and atomic force microscopy and matrix-assisted laser desorption mass spectrometry) are adept at providing highly detailed data on the size, morphology, composition, and surface chemistry of select particles. Ultimately, the analyst must select the approach best suited for their study goals. Robust quality control elements are also critical to evaluate the accuracy and precision of the sampling and analysis techniques. Further, improved efforts are required to assess and control possible sample contamination due to the ubiquitous distribution of microplastics, especially in indoor environments where samples are processed.

Tajikistan's position in the desert zone, arid climate and mountainous terrain determined the characteristics of its soil cover. The soils mainly belong to the following types: light gray soils, typical gray soils, and mountain carbonate soils. In the Republic of Tajikistan, the total land fund or total land area is 14255.4 thousand hectares, of which 3746.0 thousand hectares are farmland. Over the past 30 years, the state of land resources in the Republic of Tajikistan has deteriorated. The share of irrigated land in relation to the area of ​​agricultural land/arable land decreased from 14.8% to 14.4%; area of ​​arable land per capita – from 0.16 to 0.12 ha/person. The share of agricultural land in relation to the total territory decreased by 1%. At the same time, there are natural limitations on the area of ​​land resources of 3746.0 thousand hectares of farmland. This actualizes the need for their effective and rational use. 90% of the area of ​​rain-fed arable land shows signs of degradation, of which 40% are highly degraded. Additionally, intensive agricultural activities on mountain slopes inevitably lead to soil erosion. They are eroded, which, as the gorges grow, leads to a reduction in the area of ​​arable soil. Slopes up to 250 m high are widely cultivated without anti-corrosion measures.

Soil organisms are very important to improve soil fertility and maintain a natural balance between soil nutrient cycles, enzyme activities and biological transformation of complex substances. Typically, one gram of soil contains more than 90 million bacteria, which helps plants in nutrient uptake by converting them into forms that are available to the plants. People tend to think negatively of microbes because they are unaware of how important they are, even though they frequently behave as disease-causing agents. Similarly, the role of soil macroorganisms in improving soil structure and nutrient movement is equally significant. The use of biochar as an exuberant carrier of soil organisms in the soil ecosystem has been widely studied. Therefore, in this chapter, we will emphasis the types and functions of macro and microorganisms in the soil, the impact of biochar on soil organisms, nutrient cycling and enzyme activities.

Abstract The topography of the Porta Stabia area is defined by geomorphology of the lava plateau of Pompeii, shaped by later volcanic events as well as by the natural north–south valley of the via Stabiana. The bedrock and paleosols in this area of the plateau had been heavily quarried and terraced in the course of later building activities, but typically were shallowest on the northeastern side of the site and deepest to the southwest. Sealing the lava bedrock was a level of yellow sandy silt resulting from the Mercato eruption of Vesuvius (7,000–6,700 bce). Above, a brown sandy silt attested to weathering and biogenic soil formation processes of this material. The project did not uncover any evidence of the Ante-Plinian gray ash that covers this soil elsewhere in Pompeii. There was no evidence for human presence in the area prior to the sixth-century bce foundation of the city, likely due to the presence of swampy marshland immediately south of the later Porta Stabia.

Nocardia species—Nocardia asteroides, N. brasiliensis, and N. otidiscaviarum—are Gram-positive, filamentous, partially acid-fast bacteria. They are occasionally detectable in environmental sources such as soil, but they rarely cause infections in humans, although they can give rise to a variety of different diseases. In healthy individuals, most commonly in the tropics, they can present with cutaneous abscesses or subcutaneous infections (actinomycetoma) in which the organisms are present as clusters of filaments or grains. In immunocompromised patients they cause a disseminated or localized deep infection, with particular sites affected being the lungs or brain. Diagnosis of Nocardia infection depends on culture, although histopathology is very useful in Nocardia actinomycetomasiii. Antibiotic treatment is typically with a sulphonamide (often as co-trimoxazole for lung infections), but combinations of drugs are usually given because the responsiveness of Nocardia species is very variable.

Abstract Water main failures are very expensive for municipalities because they typically result in expenses associated with repair costs, flood damage, and loss of revenue to affected businesses. Water main failures also interrupt the operation of vital services, such as medical care and fire-fighting operations. Currently, millions of dollars are spent annually by the water utility industry and by municipalities on the repair of failed components of the water distribution infrastructure, such as components that are made from gray cast iron or "gray iron” pipe and ductile cast iron or "ductile iron” pipe. The rate of municipal water main failures is expected to increase as the existing cast iron infrastructure continues to age. The cost of repairing damages caused by broken water mains (and subsequent flooding damage) may become an important item in many municipal budgets. It is important to develop a corrosion program to prevent catastrophic failures of water mains. This paper presents a plan consisting of several phases including preassessment, indirect assessment, direct assessment, and integrity assessment of failed water mains. We will elaborate on the failure mechanisms, failure analysis protocols, and corrosion mitigation strategies for water mains that experience breaks. Water main breaks are mainly due to corrosive soil, pipe material, galvanic action, stray current corrosion, or microbiological induced corrosion (MIC). This paper provides an overview of corrosion issues commonly experienced by water main pipes, presents specific case histories involving graphitic corrosion, galvanic corrosion, stray current corrosion, and MIC. In this paper, we will introduce a graphitization sensor for condition assessment of water mains. This sensor can identify the location and extent of graphitization on water main.

Deep soil mixing (DSM) has become a widely used ground improvement technique globally, producing soil-cementitious materials for various complex civil and environmental applications. In the field, the soil-cement materials form under confining stress conditions, which are often overlooked, as most wet grab specimens are cured and tested under ambient atmospheric conditions. This oversight has led to an underestimation of the engineering and mechanical properties of the soil-cement mixed material. With support from the DFI Technical Committee Project Fund, the authors initiated a multi-phased comprehensive research study in collaboration with industry experts to gain a fundamental understanding of these effects. This study investigates the curing conditions to which in-situ materials are exposed and how these conditions influence the strength of deep mixed materials. The findings reveal that the curing conditions for in-situ materials, including applied stresses and temperatures, significantly differ from those under which typical quality control specimens are cured. Neglecting these conditions can lead to a substantial underestimation of in-situ material strength. The data compiled for this study encompass strength and temperature data obtained from specially designed laboratory bench tests, field-conducted modified oedometer tests, in-situ instrumentation tests within deep mixed columns, and a review of independent coring data from deep mixed projects across North America. Analysis of these collective studies reveals a correlation between curing stress and unconfined compressive strength (UCS). The rate of strength gains follows a linear pattern and is influenced by the soil type being treated. Fine-grain soils, in particular, exhibit a higher rate of strength gain when subjected to in-situ curing stress (with depth) compared to granular soils. The paper delves into fundamental processes such as drainage, consolidation, and interparticle behaviors of deep mixed materials from their fresh state until the treated column has cured. It also presents empirical and analytical methods to correct in-situ strength measurements to account for the effects of curing stresses.