Study On Geochemical Environmental Effects Of Mn, Cu, Cd, Pb, As In Dabaoshan Mine, Guangdong Province

Exploitation of Mine in particular sulfide mining can lead to a large number of acidic waste water discharged into the environment and leaching out of various toxic and harmful heavy metal ions. That harm to the ecological of central Mining area and rivers seriously,and affect the health of regional populations. Therefore, it is a great significance of heavy metal pollution on the mine .to research the existence of conditions of metal ions and speciation analysis.The metal ion concentrations in the river, well water, soil and sludge of river around Dabaoshan Mine of Guangdong province were examined, to characterize distribution and seasonal change of metal contamination with respect to of water quality, physical and chemical weathering and seasonal variations. The results showed that there were four types of water quality in Dabaoshan Mine: Ca-SO₄, Mg-SO₄, Ca-Mg-SO₄ and Ca-HCO₃, among which the concentration of Mn, Cu,Pb in water quality type of Ca-SO₄ was the highest, respectively with 339 mg/L, 10.614 mg/L, 0.425mg/L;while in water quality type of Mg-SO₄ the concentration of Cd, As was the highest with 0.368mg/L and 81μg/L. From the space-time distribution, the metal ion concentration of the surface water in the rainy season is less than its in the dry season, while the well water and spring water less affected by season; but for As, the concentration of As in the dry season water samples is less than in the rainy season and high concentration of As didn't be founded in the water samples. And the total soil metal analysis showed that the nature and chemical forms of metal, As well as by the nature of the transport, oxidation of weathering, erosion and water infiltration, ground water level and other factors making two quarters of the total content of metals in soil changes were different.Meanwhile, in order to further study the influence of soil factors transfer of metal ions, carried out on soil chemical forms of heavy metals and arsenic analysis and simulation of static leaching of heavy metals in soil experiments. Through the BCR method, extraction of heavy metals in four forms, results showed that: the percentage of acid extractable of Mn in the tailings profile soil samples was 11.7% to 88.0%, and in the mining creek upstream sediment was the high up to 80.1%, paddy soil was 71.3%, 32.1% for sugar cane land; for Cu its percentage of acid extractable in the pit tailings surface, the paddy soil and river sediments of Shanbacun were 34.2%, 38.47%, and 17.15%,respectively, and other forms of soil there are residual; for Cd residue percentage was 59.38% 99.4%, while acid extractable percentage in the pit tailings surface, the paddy soil and river sediments of Shangbacun were 40.27%, 16.38% and 12.94%.;finally, percentage of acid extractable of Pb was very low, were less than 5%.using six-steps method extracted the As of soil samples, the results showed that the percentage of the two biological using As of exchangeable and adsorbed was very small. simultaneously the percentage of As of crystalline Fe hydroxides adsorbed, amorphous or low crystallinity hydroxide adsorbed Fe oxides, ferrosilicon also were small. And the As of was mainly in residual fraction.Static leaching experiments in soil with pH of the solution for the 1, 3, 5, 7, 9 as extraction agent, continuous immersion. From the experimental results could be seen:The concentrations of Mn, Cu and Pb in the pH1 of the dissolution solution in the tailings profile surface, 0.5m, 1m soil and paddy soil were higher than its in the other four dissolution solutions of pH 3, 5, 7, 9, moreover the concentration of Mn, Cu and Pb in that four immersion solution of pH 3, 5, 7, 9 were similar, but the concentration of metal ions in the five different pH dissolution solutions that dipping in the midstream sediment was little difference; And for Cd, the concentration of Cd in the five different soils of five different pH immersion solutions that dipping in the topsoil, 0.5m soil, 1m soil, midstream sediment and paddy soil was similar, a curve in the Cd concentration of pH1of the dissolution solution not higher than other four curves, however after 53 days, the Cd concentration in soaking solutionfive all were suddenly dropped,and then basically didn't not change; Finaly,the concentration of As in soaking process of five soils trended to lower .In five soils sosking ,it was only 0.5m soil soaked in the process of showing the impact of pH on As dissolution, and in the remaining dissolution solution of the other four soils, the concentration of As was a little difference.