Moisture in soils

No information was located on the fate of BCME in soil. However, it is probable that BCME would rapidly hydrolyze upon contact with moisture in soil or would react with soil constituents. Consequently, it is not expected that BCME would persist for significant periods in soil. 

Soil moisture can have a significant effect on decomposition (Swift et al. 1979). This is due, in part, to the fact that soil moisture can affect the metabolism of decomposer microorganisms. This effect can be modified by soil texture because bioavailable moisture is determined, in part, by the suction with which water is held between soil particles (matric potential). Thus, the calibration of soils to a known matric potential can lead to the assessment of the effect of bioavailability of moisture in soil (Hillel 1982) and allow for the comparison of process rates between soils at the same matric potential (Orchard and Cook 1983). 

Based on this property, californium-252 has been used to prospect for oil and to test materials without breaking them apart or destroying them. The isotope can also be used to determine the amount of moisture in soil, information that is very important to road builders and construction companies. Neutrons from californium-252 can be used to inspect... 

TABLE 8.7 Composition of average precipitation and soil moisture in soils on weathered sandy dolomite near State College, Pennsylvania... 

Lacustrine Pertaining to development in lakes Mesic This term has a very broad meaning. In ecology, it refers to moderate conditions with respect to both temperature and moisture. In soil, specifically in soil taxonomy, mesic is used to represent a soil temperature (mean annual) that falls in the range 8-15° C Mole fraction The ratio of the moles of a substance to the total number of moles in the sample. In the atmosphere this is the same as the volume fraction Non-seasalt (nss) The amount of an element or compound in the bulk aerosol mass that is in excess of its seawater ratio with sodium or chloride. Often applied to sulfate Obligatory anaerobes Organisms restricted to life in anaerobic environments... 

The concept of disjoining pressure, as observed experimentally for liquid interlayers between solid surfaces and for an air bubble pressed against a surface [171], has subsequently been extended to such greatly different areas as the stability of lyophobic colloids, lubricity, and equilibrium and movement of moisture in soils, and other processes. 

The amount of moisture in soils has a considerable effect on adhesion. With increasing moisture content, the adhesive force increases because the soil becomes more sticky (see Table XII.3). For soils of the chernozem type, when the moisture content is above 70%, the strong adhesion of soil to a metal surface brings about an autohesive type of detachment when tilling the soil, so that friction of metal on soil is replaced by friction of soil on soil. According to data from other sources [341] autohesive detachment for well-structured clay and loam soils is observed at a moisture content of 80-85%, and for light soils at... 

Electrolytes affect the flow of electrons. Moisture in soils helps the flow of electrons, thus promoting the corrosion process. The ions in the electrol3rte determine the electrical conductivity as well as the acidi or alkalinity of the electrolyte, and the chemical reaction between the primary products of corrosion and the electrolyte. 

Landslide monitoring is considered to provide the necessary data that can be used for intermediate-term prediction. Appearance of cracks, fluctuation of moisture in soils, and acceleration of surface or subsurface movements provide precursory evidence of landslide movement. Specifically, the acceleration of surface or subsurface movements enables the most direct detection of impending landsliding (Voight and Kennedy, 1979). 

Contributing factors to rollovers include the various dimensions and weights of implements, operating speed, type of terrain, and moisture in soil. 

Urea and uracil herbicides tend to be persistent in soils and may carry over from one season to the next (299). However, there is significant variation between compounds. Bromacil is debrominated under anaerobic conditions but does not undergo further transformation (423), linuron is degraded in a field soil and does not accumulate or cause carryover problems (424), and terbacd [5902-51-2] is slowly degraded in a Russian soil by microbial means (425). The half-hves for this breakdown range from 76 to 2,475 days and are affected by several factors including moisture and temperature. Finally, tebuthiuron apphed to rangeland has been shown to be phytotoxic after 615 days, and the estimated time for total dissipation of the herbicide is from 2.9 to 7.2 years (426). 

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 main agents of these losses are the microbes and small animals, such as springtails and mites, that inhabit the soil. These feed on organic matter that contains carbon and nitrogen and produce carbon dioxide and ammonium ions as waste products. Other bacteria convert the ammonium to nitrate. Like most of us, these organisms are most active when the conditions suit them best, and their preferred options are warmth and moisture. In early autumn, the soil is still warm... 

This will depend upon the condition of the soil and its moisture content. This is why it is usually high where the moisture content is less than 15% of the weight of soil. The variation in soil resistivity is, however, low when the moisture content exceeds 22%. 

The resistivity of the soil in any particular location will be a function of moisture content, soil temperature and presence of dissolved salts. At a site where climatic conditions vary considerably throughout the year, earth electrodes should be buried at a depth where such changes will not affect the resistivity. Grounding rods are generally made of copper bonded onto a steel core. The copper provides a good connection to earth and offers a high corrosion resistance, while the steel core gives the mechanical... 

Moisture must be considered of primary importance in soil formation, in weathering, and in all of the changes taking place within the soil. The types of soil that form depend to a great extent upon the rainfall situation. Too little rainfall will prevent development of plant and animal life with their soil-building action. Too much moisture has a similar effect in preventing normal soil formation. 

Corrosion in soil is aqueous, and the mechanism is electrochemical (see Section 1.4), but the conditions in the soil can range from atmospheric to completely immersed (Sections 2.2 and 2.3). Which conditions prevail depends on the compactness of the soil and the water or moisture content. Moisture retained within a soil under field dry conditions is largely held within the capillaries and pores of the soil. Soil moisture is extremely significant in this connection, and a dry sandy soil will, in general, be less corrosive than a wet clay. 

This is a simplified treatment but it serves to illustrate the electrochemical nature of rusting and the essential parts played by moisture and oxygen. The kinetics of the process are influenced by a number of factors, which will be discussed later. Although the presence of oxygen is usually essential, severe corrosion may occur under anaerobic conditions in the presence of sulphate-reducing bacteria Desulphovibrio desulphuricans) which are present in soils and water. The anodic reaction is the same, i.e. the formation of ferrous ions. The cathodic reaction is complex but it results in the reduction of inorganic sulphates to sulphides and the eventual formation of rust and ferrous sulphide (FeS). 

Runoff sensitivity, particularly in arid and semi-arid climates, is largely a result of sensitivity in soil moisture response. If rainfall amount and frequency decrease, more soil moisture is lost to evapotranspiration, creating a soil moisture deficit that must be replaced before surface runoff or significant ground-water flow returns. The converse also tends to... 

The production of nitrogen fertilizers is a major activity of the chemical industry. Every year, the top 15 chemicals in industrial production in the United States include several nitrogen-containing compounds whose major use is in fertilizers. Molecular nitrogen serves as the primary source of nitrogen for chemical production. Gaseous ammonia (NH3), which is synthesized from N2 and H2, can be injected directly into the ground, where it dissolves in moisture in the soil and serves as a fertilizer. Ammonia is more widely used in reactions with acids to produce other fertilizers Ammonia and nitric acid produce ammonium nitrate (NIL) NO3), while ammonia and sulfuric acid produce ammonium sulfate. These chemicals and urea,... 

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). 

Taylor-Lovell S, GK Sims, LM Wax (2002) Effects of moisture, temperature, and biological activity on the degradation of isoxaflutole in soil. J Agric Food Chem 50 5626-5633. 

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