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.%利用磷脂脂肪酸(phospholipids fattyacids,PLFAs)法,以杭州某农药厂六六六(HCH)和滴滴涕(DDT)污染土壤为例,研究了空白(对照组)、还原铁粉、微米Fe/Cu和微米Fe/Cu+5 mmol·L-1 TX-100这4种处理对土壤中微生物群落结构的影响.结果表明:在105 d的研究时间内,微米Fe/Cu+TX-1 00组细菌生物量显著降低,可能的原因是TX-100具有一定的毒性,破坏了细胞膜的功能和结构;各组真菌/细菌生物量之比均呈上升趋势,微米Fe/Cu+TX-100组比值最大;表面活性剂TX-100对革兰阴性菌有抑制作用,还原铁粉组革兰阴性菌略有增加,微米Fe/Cu组革兰阳性菌与革兰阴性菌显著增加.还原铁粉组革兰阳性菌/革兰阴性菌比值较小,说明还原铁粉的加入改善了土壤的营养状况,而其他几组营养胁迫较强.还原铁粉和微米Fe/Cu+TX-100这2种修复方式对土壤通气有明显促进作用.各处理组微生物总生物量高于对照组,表明处理过程有助于恢复污染土壤的生态功能.通过对不同处理组PLFAs进行主成分分析,发现微米Fe/Cu与微米Fe/Cu+TX-100处理组后期原生动物明显增加.
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