Characteristics Of Heavy Metals In The City Of Kunming Precipitation

Based on the collection of meteoric water from October, 2013 to September, 2014 in Kunming city, this study analyzed the variation of pH value and conductivity of the local precipitation. Then detecting the concentration of Se and As with the usage of atomic fluorescence spectrometer, while using inductively coupled plasma mass spectrometry to analyze the concentration of Cu,Zn,Hg,Cd,Cr,Pb,Fe,Mn,Be,Co,Ni,V and other heavy metals. The main conclusions are as followings:(1) The pH value of Kunming city’s precipitation ranges from 8.12 to 8.61, the average is 8.37, which indicates that the pH value of precipitation in Kunming city is relatively stable, and tends to the alkaline precipitation. Through seasonal contrast, the pH value of rainy seasons(May to October) is a little higher than dry seasons(November to April).(2)The conductivity of Kunming city’s precipitation ranges from 13.4μs/cm to 27.6μs/cm, the average is 20.81μs/cm. Contrasting with precipitation curve during the same period, the conductivity and the rainfall is in negative correlation: the smaller the rainfall is, the higher the conductivity is. The conductivity peak appears in the dry seasons, the rainy season is significantly lower than that of the dry seasons.(3) The concentrations of Cu, Zn and Ni in precipitation heavy metals are in a higher station, the annual averages are 59.543, 3412.968 and 76.702μg/L respectively. All the detected heavy metals, whose standard have reached Grade Ⅰare Se, As, Hg and Cr, reached Ⅱ are Cu, Cd and Pb, beyond the standard detection limits are Zn, Fe, Ni and Mn, less than the detection limits of the standard are V, Co and Be.(4)By the enrichment factor analysis, concluded that the enrichment factor of 13 elements in the order: Zn> Cd> Ni> Cu> Se> Co> Pb> Mn> Hg> Cr> Be> V. Obviously, Zn and Cd are the richest ones, Co, Ni, Cu, Se, As and Pb’s enrichment are slight. As we all know, these elements mainly come from the burning of coal, industry and transportation pollution sources. Using the potential ecological risk index evaluation, it indicated that the potential ecological risk of Kunming city’s precipitation is in slight status.