| With the rapid development of urbanization,road area is increasing rapidly,Which is different from the natural surface "city second natural pattern", and produce profound effect to the surface hydrologic process.Road is an important part of urban catchment, which is also one of the main sources city containing water of nonpoint source pollution,Road runoff pollution problem increasingly attracted people's attention.Road surface, especially city road surface of traffic frequent activity, Cumulative a large number of toxic pollutants by car emissions, tires and road wear and oil leakage.Because of the impermeability of city roads,these contaminants in rainfall will be road stormwater runoff during dissolved, flushing and through urban drainage pipelines migration into the water, the water containing water to cause significant damage, and through direct and indirect way harm people healthy. These pollutants may be carried into the water by the road runoff during the heavy rainfall,which is harmful to water quality of accepted water and harm people healthy through direct and indirect way.In order to provides the basis for the urban non-point pollution control and decision,road stormwater runoff from heavy metals and some water characteristics were studied by this pape, which has certain theoretical and realistic significance.This paper selects Chery Automobile Company (industrial area),railway station (traffic area), the walking street (commercial area), south Rachel newtown (residential), (cultural and educational area) south campus of Anhui normal university for research object,The road runoff pH, SS and COD, P and heavy metal (Pb, Zn, Cu, Cr, Cd, Ni, Mn, V) were preliminary analysised,discharge rule of metal pollution event mean concentration(EMC) and first flush were evaluated,at last put forward some suggestion,the main conclusions are as follows:(1)The average rang of runoff pH value of seven times rainfall events in railway station was 7.35-7.52 ; rang of SS was 21-2450mg/L, rang of COD was 36-932mg/L; TP and RP were inferior to the surface water envorinment quality standards "Ⅱclass standards. Overall, SS and COD pollution was serious ,P is non-pollution.(2)The discharge characteristics wasvarious in different rainfall intensity: The smaller rainfall event of average rainfall intensity, total heavy metals and particle state laws were similar, which had low initial concentration in runoff early, reached a maximum after a short time, and then droped down rapidly and maintain in certain level; the dissolved state was opposite; The medium rainfall event of average rainfall intensity,The flow rule of a total metals is that initial concentration was high,got peak by certain wave, then quickly low , there was no change in later concentration; The larger rainfall event of average rainfall intensity,total amount and particle state heavy metals wer similar, which reached maximum in the begining, then reduced quickly, reach stabilizing after small fluctuations, although a small rising in some metal, but still in very low level; discharge characteristics of some dissolved metals were similar to total amount , the rest showed the flow rule of normal distribution curve.(3)In seven times rainfall events, the EMC change range of Zn,Pb,Cd,Cu,Cr,Ni,Mn and V were 0.26-1.17 mg/L,0.06 0.36 mg/L,2.12-6.39 ug/L,0.052-0.469 mg/L,0.034-0.162 mg/L,14-59 ug/L,0.24- 1.20 mg/L,24.1-9.95 ug/L, respectively.the pollution extent of Pb and Cr pollution were serious. EMC distribution size order of Zn in different functional areas was: traffic area> industrial area > residential area>business area>cultural and educational area;for the rest metals:traffic area>industrial area>residential area>cultural and educational area>business area.(4)Qualitative analysis of the first flush in seven times rainfall events illustrated that,except for 2010-04-11 and 2010-05-21, V m '(t) - V' (t) curve of total and particulate-bound metals of the rest five times located in above Angle points, which exhibited a pronounced first flush ,in addition,both of them had the same scour characteristics.Dissolved metals of 2010-04-11, 2010-05-16, 2010-06-08 and 2010-07-02 had significant first flush which did not exist for dissolved heavy metal in 2010-04-14, part of dissolved metals in 2010-05-21 and 2010-09-10 existed first flush.(5) Quantitative analysis of the first flush in seven times rainfall events showed that the range of EF25 average was 1.17-1.67, EF25 of rainfall events were greater than 1.The first flush tatio demonstrated that about 36%-42% of heavy metals could be removed from road runoff by intercepting and treating the initial 25% of the runoff water. The sequence of strength of the first flush of total metals was: Zn>Cu>Pb =Ni=Mn>Cd >V>Cr;for the dissolved metals: Mn>Cu>Zn>Ni>Cr>Pb>Cd>V; for the particulate-bound metals: Zn>Cu=Ni>Pb> Cd=V> Mn>Cr.(6) Correlation analysis suggested that the influence of rainfall on the first flush of total and dissolved metals was significant,but there was no significant influence caused by other rainfall factors; the influence of rainfall,mean rainfall intensity and antecedent dry period on the first flush of total and dissolved metals was significant. |
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