The special topography of karst areas allows organochlorine pesticides(OCPs)from the surface environ-ment to easily infiltrate the underground environment,posing a threat to groundwater security.[Methods]In this study,a gas chromatography-electron capture detector(GC-ECD)was used to detect two typical OCPs,namely,HCHs and DDTs,in the Yuquandong spring system in Zigui,Hubei.[Objective]This study investigated spatial and temporal distribution characteristics,sources and transport of HCHs and DDTs.[Results]The results showed that the mass concentrations of HCHs in the water ranged from 0.09 to 5.17 ng/L,and the mass fractions of HCHs in the soils and spring sedimentsranged from 0.36 to 3.67,0.11 to 2.53 ng/g,respectively,mass concentrations of DDTs in the water ranged from 0.13 to 7.16 ng/L,and the mass fractions of DDTs in the soils and spring sedim-entsranged from 0.22 to 19.13,0.73 to 11.53 ng/g,indicating that the pollution was dominated by DDTs.The highest mass concentrations of HCHs and DDTs in water were observed in winter;the highest mass fractions of HCHs and DDTs in the soils were observed in summer and winter,respectively;and the mass fractions of HCHs and DDTs in the spring sediments peaked in summer and spring,respectively.Characteristic ratios showed that HCHs in water,soils and spring sediments mainly originated from lindane usage,DDTs in water mainly originated from historical residues,and DDTs in the soils and spring sediments mainly originated from recent usage.Correla-tion analysis indicated that HCHs and DDTs could be transported from the surface water and the soils in the re-charge area to the spring water and spring sediments in the discharge area,respectively.The rapid transport of HCHs and DDTs across multiple media confirmed groundwater vulnerability in karst areas.[Conclusion]The study can provide a reference for the protection of karst groundwater resources and the environment.
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