Research On Environmental Behavior Of Chromium Poluutents Of Tanning Industruy

Chromium pollution is part of Heavy metals pollution, while it is particularly serious in tanning industry. In view of that, the Projects 973 of National Key Basic Research Program (No.2007CB407306) has been approved and in progress. This article belongs to a part of the project, analyzed the content,form and valence of chromium in a total of 89 samples of 4 types environmental medias, and then studied the occurrence and distribution characteristics of chromium contaminants which come from tannery through its environmental behaviour,so as to provide basic data for chromium pollution control and the migration laws of chromium, the results show that:While it was 298.64μg/L that average concentration of chromium at the sewage outfall of the tannery it was 17.81μg/L at the site of 1km away from the outfall, which was about 94% less than that at the outfall. It was also found that there was no significant change of the concentration of chromium within 1-7 km from the outfall. Their concentration of chromium at the sodium value with the background value (14.55μg/L), also have a slight fluctuation as the result of release of Cr in sediments.Distribution coefficient of chromium between the water phase and the suspended matter declined from 0.059 to 0.041 with the increase of the distance from pollution sources. The change of the distribution coefficient is concerned with CODMn, suspended solid and SS in water.Theρ(CrT) of river sediment Samples were 41.35-167.94 mg/Kg.ρ(CrT) have a poor correlation the distance from the outfall but a significant correlation with the organic matter; distribution characterized of chromium species was:S8-S13 were ranked in order of OM-Cr, Carb-Cr, EXC-Cr, WS-Cr, while S13-S15 were OM-Cr, EXC-Cr, Carb-Cr, WS-Cr;ρ(Cr(Ⅵ)) of Samples were 0.37-3.72 mg/Kg,the ratio ofρ(CrT) approximately 2.59%,the correlation coefficient was 0.9939.Theρ(CrT) of siol Samples were 47-220 mg/Kg.ρ(CrT) have a significant correlation with the organic matter; distribution characterized of chromium species was ranked in order of FMO-Cr,OM-Cr,EXC-Cr,Carb-Cr,WS-Cr;ρ(Cr(Ⅵ) of Samples were 0.43-6.18 mg/Kg, the ratio ofρ(CrT) approximately3.1%,the correlation coefficient was 0.9537.Theρ(CrT) of Drinking water samples were 6-20ug/L, andρ(CrWS) were 0.7-5ug/L, chromium is mainly affected by content of SS in drinking water. Theρ(CrT) of Wheat grass samples between the 0.8-10.2 mg/Kg, theρ(CrT) in wheat seeds were 1.75-3.3 mg/Kg, with the enrichment coefficient of 0.039-0.051.Theρ(CrT) of the surface sediments at tannery sewage outfall were 58-469.6mg/Kg,the main factors affecting were running time of the tannery, repair period, and organic matter content. With the order of the OM-Cr, FMO-Cr, Carb-Cr, EXC-Cr, WS-Cr, and with the repair time last, some Precipitation of chromium trends into the combination of organic and residual conversion.Theρ(CrT) of Core Sediments at outfall department was 50-130mg/Kg while were 0-130mg/Kg at the downstream Core sediment, the distribution of chromium in 5-45cm soil layer at the outfall was similar with 10-50cm soil layer at the downstream,and the maximum value occur in the 30-35cm soil layer, under this floor,ρ(CrT) decrease with the increase of depth.