Study on Speciation Analysis and Bioavailability of Cr in Soil by Fixatives

By the leaching experiment of soil column, e researched speciation analysis and bioavailability of Cr in soil before and after fixing. The contents of Cr in fixed soil including exchangeable chromium, carbonate bound chromium, iron manganese oxide bound chromium, organic matter bound chromium, all lower than the soil before fixing, but residues chromium is higher than the soil before fixing. There is obvious difference bioavailability in soil before and after fixing. Soil heavy metal pollution which brings a threat to agricultural product quality could cause surface water and groundwater contamination, and cause the food chain poisoning[1-2]. Compared with the organic pollutants, heavy metal pollutants does not produce decoration in environmental media, through the soil-plant system enter the food chain therefore affecting the safety of agricultural produces and harm to human health. Therefore, it is essential to begin management of the heavy metal contaminated soil. Currently，heavy metal pollution mainly come from the following fields: chromium compounds used as electroplating, leather tanning, pigments, paints, alloys, dyeing and printing, offset printing. Cr contaminated soil repair method include: biology, agricultural engineering, physico-chemical treatment. By max fixatives into the soil adjusted or changed physical and chemical properties of Cr and produce precipitation adsorption ion-exchange humification and oxidation-reduction series reaction ,situ stabilization is one of treatment methods for physical-chemical, consequently reducing mobility and bioavailability in the soil environment , thereby decreasing the toxicity hazards of Cr elements on plants and animals[5]. Since the 1950s, zeolites have a wide range of applications in various fields. Zeolite is a frame-like structure, moisture content of aluminum silicate minerals, with a porous structure, adsorption and ion exchange[6]. In this paper, not only curing effect of fixatives on the metal has been emphasized, but also fixative for friend of environment has been taken into consideration. Natural Zeolite magnesium oxide and FeSO4 have been chosen as fixative and leaching solvent select demonized water. Provide some theoretical basis and technical support for farmland Cr contaminated soil immobilized system.