Fraction of soils

The results of map generation cannot be expressed effectively with the format available here. However, the State of Oregon utilized the map and matrix techniques in their nonpoint source evaluation and as a basis for designing more intensive survey approaches to assessing the impact of human activity on river quality. In addition to reflecting deposition of sediments, the methods can be applied to transport of pesticides, nutrients and trace elements since many of these substances tend to adsorb to the organic and inorganic fractions of soil. 

Chernobyl 241Am, in five samples of surface soil collected 1.5-15 km from the Chernobyl accident in July 1987, was predominantly in the 0.005-0.25 mm size fraction of soil, which comprised 65% of the mass (Berezhnoi et al. 1991). 

Chao T.T., Sanzolone R.F. Fractionation of soil selenium by sequential Partial dissolution. Soil Sci Soc Am J 1989 53 385-392. 

Warden B.T., Reisenauer H.M. Fractionation of soil manganese forms important to plant availability. Soil Sci Soc Am J 1991 55 345-349. 

Tan Z, Lai R, Owens L, Izaurralde RC (2007) Distribution of light and heavy fractions of soil organic carbon as related to land use and tillage practice. Soil Till Res 92 53-59... 

Microbial biomass nitrogen Chloroform fumigation extraction Indicates biologically active fraction of soil nitrogen various methodologies controls nutrient cycling dependent upon organic inputs Rice et al. (1996)... 

Microbial biomass P Chloroform fumigation extraction Indicate biologically active fraction of soil phosphorous control P cycle dependent upon organic amendments Brookes et al. (1982)... 

To find out whether the N in NH-N fractions of soils was bioavailable, NH-N fractions isolated from several soils were incubated with a soil rich in day minerals, a sandy soil, and a pure sand. [8] Most of the N in the NH-N fractions was found to be... 

Soil microorganisms degrade methoprene rapidly and extensively (27). The hydroxy ester was isolated as a minor metabolite over 50% of the applied dose was evolved as 1 C02. Radioactivity from [5-1 0]methoprene incorporated into the humic acid, fulvic acid, and humin fractions of soil. 

Humin The alkali-insoluble fraction of soil organic matter or humus... 

Fulvic acid fraction Fraction of soil organic matter that is soluble in both alkali and acid... 

Organic matter extracted from earth materials usually is fractionated on the basis of solubility characteristics. The fractions commonly obtained include humic acid (soluble in alkaline solution, insoluble in acidic solution), fulvic acid (soluble in aqueous media at any pH), hymatomelamic acid (alcohol-soluble part of humic acid), and humin (insoluble in alkaline solutions). This operational fractionation is based in part on the classical definition by Aiken et al. (1985). It should be noticed, however, that this fractionation of soil organic matter does not lead to a pure compound each named fraction consists of a very complicated, heterogeneous mixture of organic substances. Hayes and Malcom (2001) emphasize that biomolecules, which are not part of humic substances, also may precipitate at a pH of 1 or 2 with the humic acids. Furthermore, the more polar compounds may precipitate with fulvic acids. 

Conventional regional soil geochemical surveys based on coarse fractions of soils (>20 mesh) to avoid windblown sand dilution for elemental contents failed to delineate uranium geochemical anomalies for blind sandstone-type uranium deposits in desert basin terrains in China. 

Figure 1 shows that concentrations of U and associated elements such as Mo, La, Ce, Au, and Th tend to increase in fine fraction of soils over the uranium deposit. This is due to the fact that U complexes [U02] " are easily adsorbed by clays. Figure 2 shows that U and Mo in -120 mesh fraction of soils give good indication to uranium deposit at the depth of 300m. 

The uranium tends to concentrate in the fine fractions of soils in which clays can adsorb uranium complex compounds [U02] " transported from uranium deposits. 

Sampling of fine-grained fractions of soils (-120 mesh) from the cemented clay-rich horizon at a depth of 15-30 cm are... 

Fig.1. Bar graphs showing the concentrations of various elements in different size fractions of soil over the Shihongtan sandstone-type uranium deposit.

Williams, C.H. (1950) Studies on soil phosphorus. I. A method for the partial fractionation of soil phosphorus. Journal of Agricultural Science 40, 233-242. 

The BioTrol soil washing system is a patented, water-based volume reduction process used to treat excavated soil. It separates slightly contaminated, coarse, washed soil particles from heavily contaminated fine soil particles. The process operates on the premise that (1) contaminants tend to be concentrated in the fine size fraction of soil (sUt, clay, and soil organic matter) and (2) contaminants associated with the coarse soil fraction (sand and gravel) are primarily surficial. The BioTrol soil washing system can be used to treat soils contaminated with petroleum hydrocarbons, pesticides, polychlorinated biphenyls (PCBs), various industrial chemicals, and metals. 

Focnses treatment on the contaminated fraction of soil. Minimizes the volnme of contaminated material. 

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