百朗地下河沉积柱芯有机氯农药的高分辨记录

测定了广西百朗地下河大石围天坑河段沉积柱芯中有机氯农药(OCPs)的质量分数,探讨了有机氯农药的垂直分布特征,结合210Pb定年研究了百朗地下河流域有机氯农药的污染历史。研究结果表明,沉积柱中总有机氯农药含量为0.42~10.63 ng/g,平均值为2.74 ng/g。百朗河流域历史上主要使用的有机氯农药有六氯苯、六六六(HCHs)、滴滴涕(DDTs)、狄氏剂和艾氏剂5种表层沉积物分析显示近年地下河流域仍有新的γ-HCH(林丹)和DDTs输入。有机氯农药的垂直分布表征百朗地下河流域在1955-1960年间六氯苯被最先使用,1961年替换为六六六,同时使用的有狄氏剂、艾氏剂农药,而滴滴涕使用可能稍晚,与我国有机氯农药的生产使用历史基本一致。研究提出了大石围天坑河段沉积柱芯中有机氯农药污的染峰值滞后于使用高峰期,与喀斯特山区土地利用方式和土壤颗粒在地下河中的迁移有关。

High-resolution Sedimentary Record of Organochlorine Pesticides in Sediment Core of Bailang Underground River, Guangxi

Organochlorine pesticides(OCPs)in the sediment core from Dashiwei Tiankeng reach of Bailang underground river were detected by GC-ECD with internal standard method.Through the study of vertical distribution characteristics of OCPs in the sediment core,the pollution history of OCPs in Bailang underground river was discussed with 210Pb dating data.Concentrations of total OCPs ranged from 0.42 to 10.63 ng/g and mean value was 2.74 ng/g.HCB,HCHs,DDTs,dieldrin and aldrin were mainly used in the basin in history.There was still new input of HCHs and DDTs in recent years.Vertical distribution of OCPs recorded that HCB was used the earliest in 1955 to 1960,and were replaced with HCHs in 1961.Meanwhile,dieldrin and aldrin were used too.DDTs were used the last,which reflected basically their production and usage history in China.The study suggested that the contamination peak of OCPs in sediment core lag behind its usage fastigium in the basin,which is related possible with land use in karst mountain area and transportation of soil particle in the underground river.