Highway Surface Runoff Pollution In Karst Areas

Karst widely distributes in our country, and its area is nearly one-tenth of land. The natural environment of Karst is fragile. Highway construction on the Karst area will be far-reaching to the environment along the line.Highway surface runoff pollution conditions, influence to circumjacent soil environment, and corresponding pollution controls have been studied in this paper.First of all, pollution characteristic and possible influence to environment of highway surface runoff are discussed. Samples from Hengyang-Zaomupu highway were samplinged and analysised. The result is found that testing values of SS, COD, BOD and Tp are hyper-III, even if the value of SS is hyper-'Integrated wastewater discharge standard'.Combined with internal and oversea study data, analyzed correlations of SS to COD, BOD, Pb, Zn and Tp, the result indicated that correlativity were preferable. And the correlativity of Zn, Cu to Pb, COD to BOD also were preferable. Through analysis and estimation of heavy metal and petroleum in soil, educed that surface runoff during operating time has some pollution to circumjacent soil environment. At the same time, by applying comprehensive index method, obtained that pollution ranks of Cu and Zn were III, while Pb was IV.Finally, aimed at the specific geologic environment, through serious comparison and analysis of several technical methods to control surface runoff pollution, a composite control countermeasures (unite Detentionbasins and Infiltrationbasins) were brought forward, and were proved efficacious and dependable in practice.The research can provide scientific reference for environmental impact assessment of highway construction and control of nonpoint pollution. It can also fill some research blanks in this professional domain, and make the contribution for environmental protection during highway construction in karst area.