Clay content

Considerable research has been conducted to investigate the soil sorption and mobiUty of dinitroaniline herbicides. In general, these herbicides are strongly sorbed by soil (354), and sorption has been correlated to both soil organic matter and clay content (355). Dinitroaniline herbicides are not readily leached in most soils (356), although leaching of triduralin is enhanced by addition of surfactants (357). 

Many factors affect the mechanisms and kinetics of sorption and transport processes. For instance, differences in the chemical stmcture and properties, ie, ionizahility, solubiUty in water, vapor pressure, and polarity, between pesticides affect their behavior in the environment through effects on sorption and transport processes. Differences in soil properties, ie, pH and percentage of organic carbon and clay contents, and soil conditions, ie, moisture content and landscape position climatic conditions, ie, temperature, precipitation, and radiation and cultural practices, ie, crop and tillage, can all modify the behavior of the pesticide in soils. Persistence of a pesticide in soil is a consequence of a complex interaction of processes. Because the persistence of a pesticide can govern its availabiUty and efficacy for pest control, as weU as its potential for adverse environmental impacts, knowledge of the basic processes is necessary if the benefits of the pesticide ate to be maximized. 

Clay content evaluation Some formations may contain nonclayey radioactive materials. Then the curve GR-U or GR-K may give a better clay content estimate. 

The pore space of a soil may contain either water or a gaseous atmosphere. Thus the aeration of a soil is directly related to the amount of pore space present and to the water content. Soils of fine texture due to a high clay content contain more closely packed particles and have less pore capacity for gaseous diffusion than an open-type soil such as sand. 

Jenny (1941) attempted to quantitatively relate the factors of soil formation to soil properties such as N, C, or clay content, depth of leaching... 

Manias, W. G., Covey, M., and Stallard, R. E. (1985). The effects of provenance and diagenesis on clay content and crystallinity in Miocene through Pleistocene deposits, southwestern Taiwan. Petrol. Geol. Taiwan 173-185. 

Clays have long been used as fillers in polymer systems because of low cost and the improved mechanical properties of the resulting polymer composites. If all other parameters are equal, the efficiency of a filler to improve the physical and mechanical properties of a polymer system is sensitive to its degree of dispersion in the polymer matrix (Krishnamoorti et ah, 1996). In the early 1990s, Toyota researchers (Okada et ah, 1990) discovered that treatment of montmorillonite (MMT) with amino acids allowed dispersion of the individual 1 nm thick silicate layers of the clay scale in polyamide on a molecular. Their hybrid material showed major improvements in physical and mechanical properties even at very low clay content (1.6 vol %). Since then, many researchers have performed investigations in the new field of polymer nano-composites. This has lead to further developments in the range of materials and synthesizing methods available. 

Poly(styrene-fc-butadiene) copolymer-clay nanocomposites were prepared from dioctadecyldimethyl ammonium-exchanged MMT via direct melt intercalation [91]. While the identical mixing of copolymer with pristine montmorillonite showed no intercalation, the organoclay expanded from 41 to 46 A, indicating a monolayer intercalation. The nanocomposites showed an increase in storage modulus with increasing loading. In addition, the Tg for the polystyrene block domain increased with clay content, whereas the polybutadiene block Tg remained nearly constant. 

The persistence of the N-nitrosamine that may be formed in soil will depend on a host of conditions, such as soil type, organic matter content, clay content, pH, the microflora present in the soil, moisture content and temperature, etc. Superimposed on all these factors will be the chemical nature of the pesticide. The N-nitrosoatrazine ( ) formed in soil from the herbicide atrazine ( ) was shown to be rapidly disappeared (1). Thus, in soil W-nitrosoatrazine was observed after one week, but was absent 4 and 10 weeks later (Table IV). In contrast, N-nitroso-butralin (11 ) persisted much longer than N-nitrosoatrazine (9) under the same conditions (Table V) and was still detectable after 6 months (3). Our studies demonstrated that N-nitrosoglyphosate is persistent in the soil. Fox soil treated with 20 ppm of nitrite nitrogen and 740 ppm glyphosate contained about 7 ppm of N-nitrosoglyphosate even after 140 days (6). 

O2 availability, water content. Structural - soil type, porosity, clay content, fertility. Agricultural - Fertilizer addition, herbicide pesticide application, tillage, cropping systems etc. 

Field studies in at least two paddies where the sediment has different characteristics of pH, texture and organic carbon contents are required for registration purposes. Since especially clay content and organic carbon content affect the agrochemical behavior in sediments, it is desirable that both systems have widely different characteristics with respect to these two criteria. These paddies should have cultivation history records on type of crop, variety, and agrochemical applications for at least 5 years. 

Spent foundry sand can be divided, based upon bonding processes, into two categories—spent green sand and spent chemically bonded sand. Spent green sand is black in color due to its carbon content, and has clay contents that result in a fraction of the material passing a No. 200 sieve (0.075 mm). Chemically bonded sands are generally yellowish in color and coarser in texture than clay bonded sands. 

Physical properties involve tests of the physical index parameters of the materials. For spent foundry sand, these parameters include particle gradation, unit weight, specific density, moisture content, adsorption, hydraulic conductivity, clay content, plastic limit, and plastic index. These parameters determine the suitability of spent foundry sand for uses in potential applications. Typical physical properties of spent green foundry sand are listed in Table 4.5. 

Topsoil should have a loose and open structure so that it drains fast to keep the ground surface dry. At the same time, it must be able to retain enough moisture in order that plants growing in it are not constantly subjected to drought stress. The properties of interest include particle gradation, clay content, nutrient content, and retention capacity. 

Spent foundry green sand is of particular interest to soil blending companies that produce topsoil, because of its dark color, clay content, moisture retention, and consistency. A high sand content is required in topsoil, so spent foundry sand could be a major component. Spent sand reduces the... 

Communication channels shall be set up between industry and academics. There has been inconsistency with regards to the characterization of foundry solid waste between industry and academics. The former cares about the workability and efficiency of materials in generating products. The latter concentrate on the technical behavior of materials if reused. The way that metal casters define the characteristics of their sands is completely different from what the contractor wants to know. For example, metal casters talk about ground fineness number, whereas contractors want to know fine and clay contents. At the point of reusing their solid waste, metal casters should divert their attention from regulators and customers to researchers, working within a well channeled system. 

Most gasoline constituents are volatile organics. Volatilization depends on the potential volatility of the compounds and on the soil and environmental conditions, which modify the vapor pressure of the chemicals. Factors affecting volatility are water content, clay content, surface area, temperature, surface wind speed, evaporation rate, and precipitation. 

Leone, J.A. Scott, E.M. "Characterization and Control of Formation Damage During Waterflooding of a High-Clay-Content Reservoir", SPE paper 16234, 1987 SPE Production Operations Symposium, Oklahoma City, March 8-10. 

Bioavailable trace elements in world arid and semi-arid soils vary widely, depending upon the nature of the parent materials, soil pH, CaC03 and clay content, and soil texture. The contents of bioavailable trace elements in arid and semi-arid soils of selected countries are presented in Table 7.6. The data are recalculated from Sillanpaa (1982) and cited from Liu (1996), Han and Banin (1997, 1999) and many others. 

In 2002, Lee et al. [51] reported the biodegradation of aliphatic polyester-based nanocomposites under compost. Figure 9.13(A, B) represent the clay content dependence of biodegradation of APES-based nanocomposites prepared with two different types of MMT clays. They assumed that the retardation of biodegradation was due to the improvement of the barrier properties of the aliphatic APSE after nanocomposite preparation with clay. However, there are no data about permeability. 

The clay content (wt. %) (Fig. 2) shows a strong positive correlation with most element concentrations in the <250pm soil analyses, e.g. Cu (Fig. 3), with distinctly low values at 400 m east. In contrast, the clays show a well defined anomaly at the bottom of the profile at 400 m east (Fig. 4), with high concentrations of Ag, Cu, Au, Cd, Co, Bi, Se, and Mn. 

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