老化对六六六在土壤中可提取态含量及其生物有效性的影响

Influence of Aging on the Extractability and Bioavailability of Hexachlorocyclohexane(HCH) in Soil

用室内模拟试验的方法研究了老化作用对六六六在土壤中可提取态含量变化及其在蚯蚓(Eisenia foetida)体内的生物富集规律.结果表明,六六六在土壤中的可提取态含量随着时间延长逐渐降低,下降速率呈现初始较快、而后减慢的趋势.在开始60 d老化时间内,α-六六六、β-六六六、γ-六六六和δ-六六六在土壤中的老化减少量是其初始添加量的57.2%、50%、52.2%和43.2%,分别是其在180 d内老化减少量的90.5%8、7.4%、72.4%和84.4%.六六六在蚯蚓体内的生物富集量和生物富集系数也表现出和老化相似的规律.不同老化时间内,六六六在蚯蚓体内的生物富集量表现为α-六六六>β-六六六>δ-六六六>γ-六六六.生物富集系数在开始的15 d为γ-六六六>α-六六六>β-六六六>δ-六六六;而后呈α-六六六>β-六六六>γ-六六六>δ-六六六的规律.老化使六六六在土壤中的可提取态含量和生物有效性降低,但仍可以在蚯蚓体内有一定的生物富集,对土壤生态安全的威胁依然存在.

Influence of aging on the extractability and bioavailability of HCHs （α-, β, γ- and δ- isomers） in paddy soil were investigated in the lab under simulated circumstances. Results indicate that extractable HCHs decreased as their contact time with soil increased. The aging rate of HCHs in soil was rather high at the initial stage, and then slowed down in the rest of the time. During the fast 60 days aging period, α-HCH, β-HCH, γ-HCH and δ-HCH dropped off 57.2%, 50%, 52.2% and 43.2% of the initial concentrations, about 90.5%, 87.4%, 72.4% and 84.4% of the total quantity of HCHs decreased in 180 d respectively due to high aging rate. Bioaccumulation of HCHs in earthworm displayed the same rule as aging, that is, the contents of HCHs in earthworm decreased as the incubation time extended, and so did bioaccumulation factors （BAF）. The contents of HCHs accumulated in earthworm showing the order of α-HCH 〉 β-HCH 〉 δ-HCH 〉γ-HCH, while the accumulative ability expressing the rule of γ-HCH 〉 α-HCH 〉 β-HCH 〉 δ-HCH in the first 15 d, and then α-HCH 〉 β-HCH 〉 γ-HCH 〉 δ-HCH in the rest incubation time. Though the extractable HCHs decreased with aging, they still can be accumulated in earthworms, thus posing potential risk to soil environment.