DNAPLs identification and distribution in the soil and groundwater of a typical coal gasification site
It is significant to identify dense non-aqueous phase liquids(DNAPLs)in the soil and groundwater for the establishment of a conceptually contaminated site model and the selection of appropriate remediation techniques.In this study,a closed gas plant in Shanxi province was taken as a research site,DNAPLs were quantitatively discriminated based on the multi-period monitoring data,and their distributions were analyzed in the soil and groundwater.The results showed that DNAPLs are mainly derived from two groundwater regions with a total area of 2.25 × 104m2.Based on results of soil stratification discrimination,most DNAPLs sites existed in silt layer,which accounted for 42.3％of the total sample points,followed by those at miscellaneous fill layer(34.6％)and at medium coarse sand layer(23.1％).This implied that DNAPLs were more likely to accumulate in the silt layer and they could penetrate into the shallow silt layer even continue to migrate downwards.Through spatial correlation analysis,it was found that the distribution range of soil DNAPLs had exceeded the groundwater DNAPLs source zone,which proved the existence of other groundwater DNAPLs source zones.The DNAPLs migration was obviously retarded by the vadose zone.At the slightly polluted region,DNAPLs only existed in the vadose zone and failed to transfer into groundwater,whereas at the seriously polluted region,DNAPLs penetrated the vadose zone and entered groundwater.Therefore,it is proposed that soil and groundwater remediation should be carried out as soon as possible to prevent the continuous release of pollutants from DNAPLs and the formation of larger groundwater pollution plumes.
国家科技期刊平台
NSTL
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