生物质炭对土壤中氯苯类物质生物有效性的影响及评价方法

通过室内培养实验,设定对照和添加1%小麦秸秆生物质炭处理,研究生物质炭对土壤中氯苯类物质老化残留的影响,并通过丁醇、HPCD和Tenax这3种化学提取方法以及蚯蚓富集实验评价土壤中氯苯类物质生物有效性的变化.老化4个月后,对照处理中六氯苯、五氯苯和1,2,4,5-四氯苯的残留率分别为29.87%、18.02%、5.16%,而添加1%生物质炭处理中六氯苯、五氯苯和1,2,4,5-四氯苯的残留率分别为68.25%、61.32%和58.02%,表明添加生物质炭能够抑制氯苯的消减.丁醇、HPCD和Tenax提取和蚯蚓富集实验结果表明,添加生物质炭显著降低土壤中氯苯的生物有效性(P<0.05),并随老化时间延长,降低效果更为显著.不同提取剂对氯苯的提取效率不同,丁醇和Tenax对氯苯的提取率为六氯苯>五氯苯>1,2,4,5-四氯苯,而HPCD对氯苯的提取率为1,2,4,5-四氯苯>五氯苯>六氯苯.添加生物质炭可显著降低蚯蚓对氯苯的生物富集因子(P<0.05).本研究表明,生物质炭能降低土壤中有机污染物的生物有效性,但高污染残留存在潜在的环境风险.

Influence and Assessment of Biochar on the Bioavailability of Chlorobenzenes in Soil

A laboratory experiment was conducted to study the influence of biochar on the residues of chlorobenzenes (CBs) in soil. Two treatments as the control and the addition of 1% wheat straw biochar were designed. Three chemical extractions as butanol, HPCD and Tenax extractions and earthworm accumulation were used to assess the changes of the bioavailability of CBs in soil. The results showed that the residues of HCB, PeCB and 1,2,4,5-TeCB in the control were 29.87%, 18.02% and 5.16% after 4 months incubation, however, the residues of HCB, PeCB and 1,2,4,5-TeCB in biochar amended soil were 68.25%, 61.32% and 58.02%, respectively, indicating that biochar amendment would inhibit the dissipation of CBs in soil. Butanol, HPCD and Tenax extraction as well as earthworm accumulation results demonstrated that the bioavailability of CBs in soil was significantly affected by biochar amendment (P<0.05). With aging time increase, the biochar amendment significantly lowered the bioavailability of CBs. The extraction ratios differed among different chemical extraction methods. The extraction ratio was HCB>PeCB>1,2,4,5-TeCB for butanol and Tenax extraction, while 1,2,4,5-TeCB>PeCB>HCB for HPCD extraction. The bioaccumulation factor of CBs by earthworm was significantly lower in biochar amended soil compared to the control (P<0.05). This study showed that the biochar could reduce the bioavailability of organic pollutants, however, the high residues of the pollutants in soil showed potential environmental risk.