Soil anions

Liu F, De Cristofaro A, Violante A (2001) Effect of pH phosphate and oxalate on the adsorption/desorption of arsenate on/from goethite. Soil Sci 166 197-208 Livesey NT, Huang PM (1981) Adsorption of arsenate by soils and its relation to selected properties and anions. Soil Sci 131 88-94 Manceau A (1995) The mechanism of anion adsorption on iron oxides Evidence for the bonding of arsenate tetrahedra on free Fe(0, OH)6 edges. Geochim Cosmochim Acta 59 3647-3653. 

Bradfield and Cooke [13] described an ion chromatographic method using a UV detector for the determination of chloride, nitrate, sulfate and phosphate in water extracts of plants and soils. Plant materials are heated for 30 minutes at 70 °C with water to extract anions. Soils are leached with water... 

Livesey, N. T., and Huang, P. M., 1981, Adsorption of arsenate by soils and its relation to selected chemical properties and anions Soil Science, v. 131, p. 88-94. 

As with cations and anions, soil interaction with molecules happens only if the substance contacts soil particles. Surface spreading or burial is insufficient the wastes must be mixed with the soil to react with it. The sensational Love Canal case, for example, involved the burial of organic liquids in 55-gallon (215-L) drums stacked in shallow trenches underground. I-tad the organic liquids been mixed and allowed to interact with the soil, the leakage and movement after the thin steel drums corroded might never have happened, and it certainly would have been less severe. 

Distinguish between specific and nonspecific reactions of anions soils. Give examples of anions that tend to be specifically and nonspecifically reactive in soils. 

The above discussion has shown that soils have the capacity to adsorb, hold, and release cations, depending upon conditions in the soil, and plant demands. They may also to a lesser extent adsorb and release phosphate anions. Soils may also fix some metals by chelation, sometimes so firmly that they are difficultly available for plants, or in other cases the movement into the plant of the chelated metal is greatly facilitated. Chlorotic plants, for example, when supplied with chelated iron may quickly turn from yellow to dark green and resume their normal rate of growth. In addition, the soil may act as a weak acid and serve as an excellent buffer against changes in pH, which is so essential for plant growth. 

Soil Nutrient. Molybdenum has been widely used to increase crop productivity in many soils woddwide (see Fertilizers). It is the heaviest element needed for plant productivity and stimulates both nitrogen fixation and nitrate reduction (51,52). The effects are particularly significant in leguminous crops, where symbiotic bacteria responsible for nitrogen fixation provide the principal nitrogen input to the plant. Molybdenum deficiency is usually more prominent in acidic soils, where Mo(VI) is less soluble and more easily reduced to insoluble, and hence unavailable, forms. Above pH 7, the soluble anionic, and hence available, molybdate ion is the principal species. 

Prevention of Soil Crusting. Acid-based fertilizers such as Unocal s N/Furic (a mixture of urea with sulfuric acid), acidic polymers such as FMC s Spersal (a poly(maleic acid) derivative originally developed to treat boiler scale) (58), the anionic polyacrylamides described previously, as weU as lower molecular weight analogues such as Cytec s Aerotil L Soil Conditioner, have all been used successfully in at least some circumstances to prevent the formation of soil cmsts. It is difficult to prove benefits in the laboratory, and field tests may give variable results depending on local weather conditions. 

S. N. Floerger, "Polymer Soil Conditioners," undated product Hterature, Saint Etienne, Erance describes functions and uses of cross-linked anionic polyacrylamides in agriculture. 

Adsorption of Metal Ions and Ligands. The sohd—solution interface is of greatest importance in regulating the concentration of aquatic solutes and pollutants. Suspended inorganic and organic particles and biomass, sediments, soils, and minerals, eg, in aquifers and infiltration systems, act as adsorbents. The reactions occurring at interfaces can be described with the help of surface-chemical theories (surface complex formation) (25). The adsorption of polar substances, eg, metal cations, M, anions. A, and weak acids, HA, on hydrous oxide, clay, or organically coated surfaces may be described in terms of surface-coordination reactions ... 

Anion A negatively charged ion in an electrolyte solution, attracted to the anode under the influence of a difference in electrical potential. Chloride is an anion. Anion exchange capacity Sum total of exchangeable anions that a soil can adsorb. Expressed as centimoles of negative charge per kilogram of soil. 

The anionic portions of the soil solution play a role of equal importance to the cations. The anions function in the manner outlined for cations in conductivity and concentration-cell action, and have an additional action if they react with the metal cation and form insoluble salts. Thus, if the metal is lead and the predominant anion is sulphate, a layer of insoluble lead sulphate may precipitate on the metal surface and form an effective barrier against further loss of metal. 

The existence of an electrical potential causes not only cation and anion movement but also migration of moisture toward the cathode. This movement of water (electroendosmosis) is due to the asymmetrical nature of the polar groups of the water molecule. In arid regions water leaving the anode area may cause the soil surrounding the anodes to become so dry that proper current densities cannot be maintained along the line. To alleviate this, some pipe-line companies have had to transport water into desert areas to re-moisten anode beds. 

As indicated above, the bicarbonate ion inhibits the process, which does not occur, therefore, in many supply waters attack is most likely in waters which by nature or as a result of treatment have a low bicarbonate content and relatively high chloride, sulphate or nitrate content. The number of points of attack increases with the concentration of aggressive anions and ultimately slow general corrosion may occur. During exposure of 99-75% tin to sea-water for 4 years, a corrosion rate of 0-0023 mm/y was observed . Corrosion in soil usually produces slow general corrosion with the production of crusts of oxides and basic salts this has no industrial importance but is occasionally of interest in archaeological work. 

The liquid in which the SAH swelling takes place in real soil (the soil solution) always contains a more-or-less wide set of dissolved salts. Their nature and amount depend on the soil composition, the degree of its salinity, the nature of water entering the soil (rainfall, irrigation, river, or groundwater), the fertilizers used. As a rule, alkali cations, Ca2 +, Mg2+, Fe3+, Al3+, and anions CP, CO, SO4, etc. are the main components of the soil solution there exist various models of soil solution and nutrient mixtures employed in research, including SAH testing. 

In 1991 the use of amidether carboxylate in combination with anionics like alkanesulfonate, alkylbenzolsulfonate, and alkyl ether sulfate to improve mildness and foam properties in the presence of soil was described [72]. Later a comparison study of the use of alkyl ether carboxylate, amidether carboxylate, and cocamidopropylbetaine in concentrated dishwashing formulations showed, in addition to the above-mentioned properties, the advantage of ether carboxylates in the construction of highly active formulations [144]. 

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