Heavy metals in environmental media around drinking water conservation area of Shanghai

The levels of heavy metals in Shanghai drinking water conservation area were determined, and the spatial distributions and main sources of heavy metals were investigated. Moreover, the ecological risk assessment of heavy metals was conducted. Some conclusions can be drawn as follows: 1, The average concentrations of Cd, Hg, Pb, Cu, Zn, Ni, Cr and As in road dust were 0.80, 0.23, 148.45, 127.52, 380.57, 63.17, 250.38 and 10.37 mg·kg^-1 respectively. In terms of the pollution level, the values of soils were relatively lower, with the mean contents of 0.16(Cd), 0.33(Hg), 30.14(Pb), 30.66(Cu), 103.79(Zn), 24.04(Ni), 65.75(Cr) and 6.31 mg·kg^-1 (As) severally; meanwhile the average levels of heavy metals in vegetables were 0.010(Cd), 0.016(Hg), 0.36(Pb), 12.80(Cu), 61.69(Zn), 2.04(Ni), 2.41(Cr) and 0.039 mg·kg^-1(As) respectively. 2, Semivariogram and multivariate analysis indicated that heavy metals pollution of soils was induced by anthropogenic activities mostly, and the pollutants produced by traffic were the major source of heavy metals in road dust. 3, The order for heavy metal enrichment coefficients of vegetables was as following: Zn(0.589) > Cu(0.412) > 0.102(Ni) > Cd(0.059) > Cr(0.061) > Hg(0.056) > Pb(0.012) > As(0.007), and the results indicated that Cd and Zn in vegetables were mainly from the soils, and the other metals were probably from the pollutants in the atmosphere. 4, Sediments in drinking water conservation area were probably derived from soils around; however, there was no significant relationship between heavy metals contents of them. 5, The results of ecological risk assessment of heavy metals showed that heavy metals in soils were in no-warning to warning situation, and warning to light-warning situation for road dust and vegetables. The fuzzy synthesis judgment for all the environmental media around drinking water conservation area was warning to light-warning.