碳源对工业污染场地土壤中HCHs和DDTs降解的促进作用

我国对有机氯农药的大量需求使得在农药生产、加工和分装等过程中造成了许多城镇中存在有机氯农药污染场地,限制了土地的后续开发利用.本研究选取3种类型的碳源组成有机修复剂A、B、C,添加到受有机氯工业污染场地土壤中进行微生物降解试验,并对比了3种修复剂的效果.试验过程中,反应体系水分含量为50％,添加零价金属调节氧化还原电位,采用好氧/厌氧交替循环方式进行生物降解.实验结果表明:3种修复剂对HCHs和DDTs的降解都有显著促进作用.与DDTs相比,HCHs较易降解.90 d内,添加修复剂(A、B、C)的处理中∑HCH的浓度分别从73.37~85.71 mg·kg^-1降解到了15.88~38.21 mg·kg^-1.与未添加修复剂的对照相比较,∑HCH的降解率提高了19%~52%,90 d内,ΣHCH的降解率最高可达81%.添加修复剂(A、B、C)的处理中ΣDDT的浓度分别从91.68~119.79 mg·kg^-1降解到了45.1~60.7 mg·kg^-1,相对未添加修复剂的对照试验,∑DDT的降解率提高了39%~45%,30 d内∑DDT的降解率最高可达到51%,但30 d后降解效率无明显增加.就不同类型碳源的促进作用来看,C/N最高,而含水率最低的修复剂B的效果最好,而C/N比最低而含水率最高的修复剂A效果最差.

Effect of carbon sources on the degredation of HCHs and DDTs in industrial polluted field soil

A large demand for organochlorine pesticides in China results in many contaminated sites in towns,limiting the subsequent development of land use.This study selected three different carbon sources as co-metabolism substrates and also compared the effects of three carbon sources to increase the biodegradation rate of HCHs and DDTs.In the experiment,the moisture was adjusted to 50%,zero-valent metal was added to reduce the redox potential and the aerobic /anaerobic cycle method was used.The result indicated that the addition of amendment A,B and C could enhance the degradation rates of HCHs and DDTs dramatically.The degradation rates of HCHs were higher.After 90 days,the ∑HCH concentration of the treatments with amendments(A,B,C) decreased from 73.37~85.71 mg · kg-1 to 15.88~38.21 mg · kg-1.The degradation rate increased by 19%~52% compared with the control.The maximum degradation rate of ∑HCH was 81% in 90 days.Degradation of DDTs was more difficult,and the ∑DDT concentration of the treatments with amendments(A,B,C) decreased from 91.68~119.79 mg · kg-1 to 45.1~60.7 mg · kg-1.The degradation rate increased by 39%~45% compared with the control.The maximum degradation rate of ∑DDT was 51% in 30 days.Amendment B with the highest C/N ratio and the lowest moisture is most efficient one to promote the biodegradation process,followed by C and A.