The Migration Of Heavy Metals In The Surface Runoff Of Dabaoshan Mining Area

During the mineral exploitingA mine tailings were generated in large quantities and exposed to open air. Metal sulphides in the tailings were oxidized chemically and biologically to produce large amounts of dissolved metalsA sulphateA and acidity. The metals and sulphuric acid constitute acid mine drainage (AMD) which was a widespread environmental problem that causes adverse effects to the quality and the ecology of river.In the paperA heavy metals dissolved in the runoff which loaded in the downstream of the Dabaoshan Mine area were studied through systemic field investigationsA sampling and lab analyzing. The laws of migration model of heavy metals in the runoff were indicatedA which will provide scientific basis for the treatment of AMD pollution.Water samples and sediment samples were achieved in eight typical sections signed as S0 to S7 from the Nov. 2009 to Aug. 2010 in the dry season and rain season respectively. Used the methods of ICP AES and IC to analysis the concentrations of heavy metal of CuA PbA CdA Zn and anion of Cl A NO3 A SO42 .The laws of migration model of heavy metals in the runoff were concluded as followedA1. The polluted degree of the acid mine drainage which derived of the mine tailing in Dabaoshan area was decreased gradually along the river flow. The concentrations of Cu Zn Cd and Pb all exceeded the surface water quality standard . The concentration of Cu Zn Cd and Pb were 10A38A42 and 6 times of the standards in dry season and 5A37A33 and 8 times of the standards in rain season respectively. Zn and Cd were the most serious pollution elements.2. The concentrations of the four heavy metals had the negative correlations with the pH valueA which indicated that the concentrations of the four heavy metals were decreased while the pH value was increased along the river flow.3. Among the three anionsA the concentration of sulphate ion had the same variation trend with the heavy metalsA which showed the concentration sulphate ion was decreased along the river flow. But the phenomena were not observed in the other anions.4. The part of heavy metals of water precipitated and accumulated in sediments presented different pollution levels. The rank of the pollution level wasA Zn>Pb>Cu>Cd. The concentration and fluctuation of the heavy metals in dry season was higher than that in rain season in sediments. The main reason is the river sediments and the enrichment of heavy metal ions in the right conditionsA the re released into the water caused.