Joint effects of Cd and thioglycollic acid on soil microbial activity

The co-occurrence of Cd with thioglycolic acid (TGA), and their joint effects on soil microbial activity have not been systematically investigated. In this study the impact of Cd and TGA as combined pollutants on soil microorganisms was investigated. The effects of single and combined pollutants of Cd and TGA at different concentrations on soil microbial metabolism activity and hydrolysis of fluorescein diacetate enzyme activities were studied under laboratory conditions. The results showed that Cd (20.0 mg kg−1) and high concentrations (400 and 1600 mg kg−1) of TGA had inhibitory effects on microbial activity, TGA was degradable without persistent toxicity. Although the complex Cd(OOCCH2S) had little influence on microorganisms, the biochemical reaction in soil would release Cd(OOCCH2S) to toxic Cd2+. Over time, FDA hydrolysis enzyme changed irregularly because of the variable concentrations of Cd2+ and TGA. TGA could decrease the level of exchangeable Cd, and Cd could slacken the degradation process of TGA. The multivariate analysis revealed that there was an association between Cd and TGA which influenced biological properties in mixed contaminated soils. The findings of this study have reference value in metal-organic mixed contaminated sites.