某林丹生产企业搬迁遗留场地土壤中六六六的残留特征

Residual Characteristics of HCHs in Soils of a Former Lindane Production Enterprise

为了解有机氯农药生产企业搬迁遗留场地土壤的污染状况,于2010年11月对原新乡市某林丹生产企业搬迁遗留场地进行了调研,采用索氏提取-气相色谱-电子捕获检测器(SE-GC-ECD)法对其污染土壤中六六六(HCH)进行分析检测.结果表明,在所有采样点位中,六六六的4种异构体的检出率均为100%.0～20 cm表层土壤中六六六的浓度变化具有波动性,总残留量(ΣHCH)范围在0.034 3～19.560 8 mg·kg-1;前后院中心0～80 cm垂向土壤中六六六浓度随土壤深度的增加呈现先增加后减小的趋势,总残留量(ΣHCH)范围在0.031 3～0.294 7 mg·kg-1.通过对污染物的组成分析发现,4种异构体的含量顺序符合β-HCH>δ-HCH>γ-HCH>α-HCH,β-HCH异构体的平均含量在50%左右,远远高于其它异构体的含量,表明该场地并没有新的六六六输入.采用《土壤环境质量标准(GB 15618-1995)》对污染场地土壤残留六六六进行风险评价,结果表明,经过十几年的降解,大部分采样点位六六六的污染浓度(67.9%)低于土壤环境质量二级标准0.5 mg·kg-1,处于安全级别,厂区后院西部及东部靠近生产车间的土壤污染仍较为严重,超出土壤环境质量三级标准(1.0 mg·kg-1)1.5～20倍,存在较大的安全隐患和风险.

In order to study the soil pollution status of the fields left by organochlorine pesticide manufacturing enterprises,soils from a former lindane production enterprise of Xinxiang were investigated in November,2010.A soxhlet extraction-gas chromatography-electron capture detector（SE-GC-ECD） method was used to detect the HCH residues in the contaminated soil samples.Results showed that the detection rate of the four HCHs isomers in each sampling site was 100%.In the 0-20 cm topsoil,concentrations of HCH residues（∑HCH） changed with volatility,ranging from 0.034 3 to 19.560 8 mg·kg-1.In the soil layer at 0-80 cm depth and around the center point,concentrations of HCH residues（∑HCH） first increased and then reduced while the soil depth increased,varying from 0.031 3 to 0.294 7 mg·kg-1.Analysis of HCH composition showed that concentrations of the four isomers were in the order of β-HCHδ-HCHγ-HCHα-HCH.The average percentage of β-HCH isomer was approximately 50%,which was obviously higher than those of the other isomers,indicating that there was no recent input of HCH.The results showed that over the recent decades,the HCH level in most of the soil samples（67.9%） were below the residue criterion of 0.5 mg·kg-1 of the China Soil Environmental Quality Standard（GB 15618-1995）,indicating that they were safe.However,soil samples in western and eastern parts of backyard near the production plant were still seriously contaminated,the HCH concentrations in which were 1.5-20 times higher than the residue criterion of 1.0 mg·kg-1 of the China Soil Environmental Quality Standard,causing great potential safety hazard to human and environment.