兰州周边地区土壤典型有机氯农药残留及生态风险

Typical organochlorine pesticides residues in topsoils and ecological risk of Lanzhou surrounding areas,China

应用Agilent 7890-5975C GC-MSD对兰州及其周边地区16个表层土壤样品中HCHs和DDTs残留水平进行分析,并对兰州周边地区土壤中OCPs的可能来源和生态风险进行了初步研究.结果表明,研究区土壤中HCHs残留范围为8.22×10-2—4.49 ng.g-1,平均值为6.85×10-1ng.g-1;DDTs残留范围为1.41×10-1—120 ng.g-1,平均值为16.9 ng.g-1;DDTs残留较HCHs占优势,约占二者总残留量的96%.α-HCH/γ-HCH比值介于0.18—14,平均值为2.8,推测研究区土壤中HCHs残留源于工业HCHs和林丹的混合源,并且可能存在有周边地区HCHs的大气长距离输送.DDE/DDD比值介于0.35—4.8,平均值为2.1,说明研究区土壤中DDT以有氧方式降解为主;(DDE+DDD)/DDT比值介于0.067—0.69,平均值为0.30,o,p'-DDT/p,p'-DDT比值介于0.091—2.8,平均值为0.60,表明研究区土壤DDTs污染可能主要源于工业源DDTs.与国内其它地区土壤相比,研究区土壤中HCHs和DDTs残留量相对较低;依照国家《土壤环境质量标准》(GB-15618—1995),研究区土壤中HCHs和DDTs残留处于较低水平;研究区土壤中HCHs残留处于较低的生态风险,DDTs残留对于土壤生物和鸟类具有一定的生态风险,而对于哺乳类动物生态风险较低.

16 topsoil samples were collected in Lanzhou and the surrounding areas.The HCH and DDT residues in these samples were determined using Agilent 7890-5975C GC-MSD.The possible sources and ecological risk of HCHs and DDTs were appointed and assessed preliminarily.The results showed that the OCP residue levels were in the range of 8.22×10-2—4.49 ng · g-1 for HCHs and 1.41×10-1—120 ng · g-1 for DDTs in the topsoil,respectively.And the average concentrations were 6.85×10-1 ng · g-1 for HCHs and 16.9 ng · g-1 for DDTs.These study results also showed that DDTs was dominant in topsoil of surrounding areas,accounting for 96% of the total residues of HCHs and DDTs.Furthermore,ratios of α-HCH/γ-HCH ranged from 0.18 to 14,with an average of 2.8,while ratios of（DDE＋DDD）/DDT were from 0.067 to 0.69,with a mean value of 0.30,and o,p′-DDT/p,p′-DDT were from 0.091 to 2.8,with a mean value of 0.60 in the surrounding areas of Lanzhou.The results indicated that the sources of HCHs were from the technical HCHs and Lindane,and the long-range atmospheric transport;DDT residues were mainly from technical DDTs.Compared with the levels of soil in other regions and China′s Environment Quality Standard for Soils（GB15618—1995）,the topsoil burden of HCHs and DDTs in surrounding areas of Lanzhou was lower.The ecological risk of HCH residue in topsoil of surrounding areas of Lanzhou was low,and DDTs might have certain ecological risks on geobiont and birds,while its risk was low on mammal.