Effects Of Complex Pollution Of LAS And Cadmium On The Growth Of Soybean (Clycine Max)

Effects of single and complex pollution of LAS (dodecyl benzene sulfonic acid sodiumsalt) and/or cadmium (Cd) on the growth of soybean (Clycine max) were studied with pot culture experiments, and the biological effects and toxicological mechanisms were discussed. The conclusions are summarized as follows:The growth of soybean plants was seriously inhibited in the soils with 5 and 10 mg/kg of Cd. The plant heights, dry weights, chlorophyll contents and SOD (superoxide dismutase) activities in the leaves decreased, while MDA (malondialdehyde) contents in the leaves increased. Single LAS could make soybean grow better at lower concentrations (<15 mg/L), however LAS was toxic to soybean at higher concentrations (>50 mg/L).LAS could partly mitigate the toxicity of Cd to soybean plants. When treated with a 50 mg/L of LAS solution, this effect of mitigating toxicity was most significant, indicating that LAS had an antagonism effect with Cd to soybean plants.The sequence of Cd contents in various organs of soybean plants was root > stem > leaf. Addition of LAS solution modified the Cd mobility in soybean plants. In the soils with the same Cd pollution level, lower Cd contents were observed in the plants treated with LAS solutions of higher concentrations.Contents of various species of soil Cd increased with increasing external Cd concentrations. In the conditions of single Cd pollution and of the same external Cd levels, the Cd contents in soybean plants were positively related to exchangeable Cd and/or to carbonate bound Cd in the soils. In contrast, those Cd contents were negatively related to Fe-Me oxide bound Cd and/or to organically bound Cd.No significant changes were observed for the contents of various species of soil Cd when treated with lower LAS concentrations (<15 mg/L); however, the contents of exchangeable and/or to carbonate bound Cd decreased significantly, and those of Fe-Me oxide bound and/or to organically bound Cd increased, when treated with higher LAS concentrations (>50 mg/L). This indicated that LAS decreased the mobility and bio-availability of Cd in the soils.