Pollution Status And Variation Of Heavy Metals In Stormwater Runoff In Xi’an

Due to accelerate the expansion of urbanization, leading to urban non-point sourcepollution problems worse. Stormwater runoff containing heavy metals directlydischarge is one of the important reasons direct discharge of urban water environmentfrom pollution.Taking Xi’an city as an object, to carry out research on the heavy metalstemporal distribution of stormwater runoff. According to the urban layout, road type,road capabilities, the flow of people, traffic conditions and other factors, set up13representative sampling points and collected rainwater runoff samples.Then, usedICP-MS to measure the Fe, Mn, Pb, Zn, Al, Cd, Hg, As, Cu and other nine commonheavy mentals content of urban stormwater and analyzed the relationship betweenheavy metal content in rainwater runoff and road materials, road busy degree and thecharacteristic changes with the seasons. Finally, discussed the sources of heavy metalpollutants and how to prevent, and evaluated potential ecological risk of heavy metalsin Xi’an. The major achievements in this paper were expressed as following:(1) Xi’an urban stormwater runoff Hg concentrations range from0.11to27.38g/Land over class Ⅴstandard of the "surface water quality standards"(GB3838-2002), Pband Zn exceed GB ClassⅠstandard, Mn and Fe also exceed national standard, but As、Cu、Cd、Al does not exceed national standard.(2) Concentrations of Mn and Zn exhibit a trend that winter> autumn> summer ofthe year> spring trends; Change in the concentration of Pb exhibit that winter> spring>summer> autumn; Hg and As content trends generally show that winter> spring>summer> autumn; In addition, Cd maximum concentration appears in winter; thehighest concentration of Fe appears in spring and summer; Al and Cu exhibit the highest concentration in summer.(3) Fe maintains high levels throughout the year and its concentration increaseswith the intensity increase of human activities; Pb concentration increases with theincrease in traffic volume; Hg levels are directly relates to the burning of coal in winter;Mn concentration and metal smelting process have a definite link. Meanwhile, coalcombustion in winter rain is the major contribution factor to various heavy metals inrunoff.(4) Factor analysis shows that Fe and Al is affected by the same sources (naturalsources). Cu, Mn, As, Zn and Cd affected seriously by anthropogenic sources. Hg andPb deeply affected by the third source.(5) Heavy metals ecological risk in Xi’an stormwater runoff belong to minorecological hazard rating, so the ecological environment is more optimistic.