Soil interactions water content effect

Water potential" (which determines ease or difficulty of obtaining water), temperature and pH all affect fractal structure of mycelial systems. Moreover, they exert interactive effects with each other and with other abiotic variables, e.g. sand content of soil [66, 68], Temperature effects on fractal dimensions of Stropharia caerulea were variable (Table 8.3) [69]. At 5°C, it took 9 days longer to achieve the Dgs values obtained at 10-20 °C, and 12 days longer to achieve the Dbm values for Stropharia caerulea. At 25 °C, both fractal dimensions of Stropharia caerulea were significantly lower than values of mycelial systems at 10-20 °C, until 26-29 days. There were also slight intraspecific differences between strains of Stropharia caerulea [69]. For Phanerochaete velutina, both fractal dimensions at 5 °C were significantly less than at 10-25 °C for the first 20 days and 14 days respectively. It is unclear what is mediating these temperature effects. 

The rate at which a chemical volatUizes from soil is controlled by simultaneous interactions between soil properties, chemical s properties and environmental conditions. Soil properties that affect volatilization include soil water content, organic matter, porosity, sorption/diffusion characteristics of the soil, etc. chemical s properties that affect volatilization include vapour pressure, solubility in water, Henry s law constant, soil adsorption coefficient, etc. and finally, environmental conditions that affect volatilization include airflow over the surface, humidity, temperature, etc. VolatUization rate from a surface deposit depends only on the rate of movement of the chemical away from the evaporating surface and its vapour pressure. In contrast, volatilization of soil-incorporated organic chemicals is controlled by their rate of movement away from the surface, their effective vapour pressure at the surface or within the soil, and their rate of movement through the soil to the vapourizing surface. 

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. 

The indirect pathway by which air pollutants interact with plants is through the root system. Deposition of air pollutants on soils and surface waters can cause alteration of the nutrient content of the soil in the vicinity of the plant. This change in soil condition can lead to indirect or secondary effects of air pollutants on vegetation and plants. 

This may be attributed to water sorption by free RAMEB, that is, RAMEB molecules that did not interact with the sandy soils. For soil S5 of medium clay content (25%), the effect of RAMEB on water sorption was small, which can reflect a balance between the two tendencies described above. 

Lodge et al. 1968) that the greater sulfate content of precipitation water in an arid environment is due to mineral dust particles and to the effect of evaporation below the cloud base. Soils in these areas contain calcium carbonate and calcium sulfate in significant proportions. Calcium carbonate particles in the air are transformed into calcium sulfate by reacting with sulfur dioxide. The process is an interesting interaction of natural and man-made trace constituents. 

The influence of the organic content of the soil and the temperature on the analyte recovery in the HS-SPME analysis of different soils mixed with water was studied. " The increase of organic matter clearly decreased the analyte recovery. Hence it was demonstrated that the organic matter is the principal element responsible for the soil-analyte interaction. To counteract this effect, the soil-water mixtures were heated up to 110 or 120°C for 10 min and cooled rapidly before extraction at 30°C with the SPME fiber. For each type of soil the recoveries increased with the increase in temperature. This effect was clearer for more volatile BTEX than for less volatiles ones. 

In contents, there are few research on non-sudden environmental risks and potential watershed secondary pollution. Research on environmental risk factors mainly are single factor, few studies on the effects of interactions of multiple factors. Current work mainly study chemical environmental risk in basin water body, but few research on soil environmental risks, air environmental risks and ecological environmental risks. 

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