Chemistry soil, factors affecting

Little is known concerning the chemistry of nickel in the atmosphere. The probable species present in the atmosphere include soil minerals, nickel oxide, and nickel sulfate (Schmidt and Andren 1980). In aerobic waters at environmental pHs, the predominant form of nickel is the hexahydrate Ni(H20)g ion (Richter and Theis 1980). Complexes with naturally occurring anions, such as OH, SO/, and Cf, are formed to a small degree. Complexes with hydroxyl radicals are more stable than those with sulfate, which in turn are more stable than those with chloride. Ni(OH)2° becomes the dominant species above pH 9.5. In anaerobic systems, nickel sulfide forms if sulfur is present, and this limits the solubility of nickel. In soil, the most important sinks for nickel, other than soil minerals, are amorphous oxides of iron and manganese. The mobility of nickel in soil is site specific pH is the primary factor affecting leachability. Mobility increases at low pH. At one well-studied site, the sulfate concentration and the... 

We begin with a discussion of the most common minerals present in Earth s crust, soils, and troposphere, as well as some less common minerals that contain common environmental contaminants. Following this is (1) a discussion of the nature of environmentally important solid surfaces before and after reaction with aqueous solutions, including their charging behavior as a function of solution pH (2) the nature of the electrical double layer and how it is altered by changes in the type of solid present and the ionic strength and pH of the solution in contact with the solid and (3) dissolution, precipitation, and sorption processes relevant to environmental interfacial chemistry. We finish with a discussion of some of the factors affecting chemical reactivity at mineral/aqueous solution interfaces. 

A variety of factors affect the horizontal and vertical migration of PAHs, including contaminant volume and viscosity, temperature, land contour, plant cover, and soil composition (Morgan Watkinson, 1989)- Vertical movement occurs as a multiphase flow that will be controlled by soil chemistry and structure, pore size, and water content. For example, non-reactive small molecules (i.e., not PAHs) penetrate very rapidly through dry soils and migration is faster in clays than in loams due to the increased porosity of the clays. Once intercalated, however, sorbed PAHs are essentially immobilized. Mobility of oily hydrophobic substances can potentially be enhanced by the biosurfactant-production capability of bacteria (Zajic et al., 1974) but clear demonstrations of this effect are rare. This is discussed below in more detail (see Section 5 5). 

Mattigod, S. V., Sposito, G., and Page, A. L. (1981). Factors affecting the solubilities of trace metals in soils. In Chemistry in the Soil Environment (M. Stelly, ed.), pp. 203—221. American Society of Agronomy - Soil Science Society of America, Madison, WI. 

The chemistry of Mo makes a larger proportion of adsorbed molybdates soluble and available at alkaline pH than at acid pH. However, pH is only one of several factors that affect the availability of Mo. Assessment of Mo availability in an alkaline soil, as in any other soil, necessitates determination of the critical limits for Mo in soils and in plants based on specific soil-plant systems. The determination of the critical limits should make allowance for the dominant soil factors that affect availability and for the plant efficiency of absorption and utilization of Mo. Use of multiple-regression equations to account for the contributions of the individual factors (Sillanpaa, 1982) will make the critical limits more predictable. 

The book reviews our knowledge of the chemistry and mineralogy of Mo, the extraction of available Mo from various soils, the various analytical methods of determining Mo content in soils and plants, the biochemical role of Mo in crop production, the technology and application of Mo fertilizers to crops, the responses to Mo of various temperate and tropical crops. Mo deficiency and toxicity in various plant species, the interaction of Mo with other plant nutrients, and the distribution of Mo within the plant. Factors affecting the availability of soil Mo to plants and Mo status in the semiarid and subhumid tropics are also discussed. 

No information specifically related to transformation and degradation in sediment and soil was identified in the available literature. However, chemical speciation of zinc in sediment and soil is probably affected by the same factors affecting its fate in water. The sediment and soil chemistry of zinc are governed primarily by the pH and the physical properties of sediment and soil. In acidic... 

System reliability is of the utmost importance to water suppliers and their customers. However, corrosion problems can vary greatly within a single system because many variables affect corrosion, for example, pipe material, pipe age, pipe wall thickness, water additives, corrosion inhibitor treatment, soil chemistry, soil moisture content and/or local groundwater level, and stray currents [2]. Table 8.2 summarizes some of the physical, environmental, and operational factors that can affect the deterioration rate of water distribution systems and lead to their failrue [4]. 

The results presented in this section indicate that all surfactants may not be suitable for surfactant-enhanced desorption. Multiple factors may influence the suitability of a surfactant for surfactant-enhanced desorption. These factors have been discussed previously. It is clear that additional research is needed to better understand how surfactant molecular structure and soil composition/chemistry affect the rate of solute desorption. However, the results presented in this chapter and in other studies indicate that surfactant-enhanced remediation of aquifers is a promising technology that needs to be explored. 

One factor that has been linked with long-term changes in the chemistry of surface waters and soils is the influence of variations in weather, particularly temperature and precipitation. The variability that fluctuations in weather induce in surface water chemistry (Hindar et al. 2003) may obscure the detection of trends resulting from reductions in SO/ deposition. On the other hand, use of long-term data may obscure shorter trends occurring within the series, particularly if the trends are not uni-directional. In this case, the detection of trends may be dependent on the time window used in the analysis, and can affect both the detection of the presence and the direction of a trend (Clair et al. 2002). For example, Clair et al. (1992) found significant decreases in SO/ concentrations in lakes in Nova Scotia, Canada, for the period 1983-1989, but with the addition of two more years of data, many of these trends were reversed (Clair et al. 1995). 

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