Environmental Behavior Of Chrome In Soils Around Residue Piling Yard In Qinghai Haibei Chemical Plant

The former Haibei Chemical Plant, located in Haiyan County, Haibei District of Jinyintan prairie where the Huangshui River derived, was built in 1988, began to run in 1989, and went bankrupt in 1999. Among the decade of production, 4000 tons of chromate was produced, accompanied with amount of wastewater with high Cr6+ concentration, pregnant antimony solution, and 48000 m3 residues. As a result, groundwater and soils are heavily polluted. Soil is the transition zone through which pollutants enter into groundwater. Therefore, studying the behavior of Cr in soils will provide scientific instruction for the treatment of pollution accident and thus protect groundwater.In this study, field investigation and laboratory analysis were combined to study soil Cr pollution condition in Cr residue piling yard soils, the extraction of Cr by different extractants, the releasing of soil Cr at different solutions and solution pH conditions, and the sorption of Cr(III) by soils around residue piling yard. The objective is therefore to reveal the behavior of Cr in pollutant soils so as to provide evidence for the treatment of Cr polluted soils and prevention of Cr pollution in groundwater in similar cases. The main conclusions of the study are as follows:1.Soils around the residue piling yard was seriously polluted by Cr. Soil Cr content was greatly higher than that in Chinese soil and the background value of soil environment in Qinghai Province. With the increase of the distance from residue piling yard, soil Cr content was decreased dramatically. Besides, the relationship between soil Cr content and the distance can be well described by linear and power function, however, power function was better than linear function. The content of Cr in soil profile was lower in upper soil and higher in lower soil.2.The divalent chromium in solutions are Cr2+ and Cr(OH)+, suggesting that Cr2+ and Cr(OH)+ are the major forms of divalent chromium in soil solution.3.The contents of different Cr fractions in the soils presented as Min-Cr > Ex-Cr > Carb-Cr > Om-Cr > Ox-Cr. Besides, the Cr contents in different fractions are all significantly higher than that in farmland soils. In soil profiles, Ex-Cr, Carb-Cr and Om-Cr show similar distribution pattern, while Ox-Cr increased with the soil depth.