Abstract:
Effects of remediation of hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) contaminated soil with reduced iron powder (Treatment Ⅰ), micron Fe/Cu (Treatment Ⅱ) and micron Fe/Cu+5 mmol·L
-1 TX-100 (Treatment Ⅲ), separately on structure of the soil microbial community therein were studied through a field experiment using the phospholipid fatty acid (PLFAs) method. Results show that the microbial decreased in biomass significantly, 105 days after the plot was treated with Micron Fe/Cu+TX-100, which is probably attributed to the toxicity of TX-100, damaging the structure and function of cell membranes. The fungi/bacteria ratio in biomass increased in all the treatments, particularly in Treatment Ⅲ. Surfactant TX-100 inhibited gram negative bacteria, while reduced iron powder increased the bacteria slightly. However, micron Fe/Cu had both gram positive bacteria and gram negative bacteria increased significantly. In Treatment I, the ratio of gram positive bacteria/gram negative bacteria, which indicates that Treatment Ⅰ improved soil nutrition, while Treatments Ⅱ and Ⅲ triggered certain nutrient stresses. Treatment Ⅰ and Treatment Ⅲ had obvious promoting effect on soil aeration. The significant increase in total microbial biomass in all the treatments reveals that these treatments are conducive to restoring ecological functions of the contaminated soil. Principal component analysis of PLFAs demonstrates that soil protozoans grew significantly in number during the later stages of the processing in Treatments Ⅱ and Ⅲ.