Pollution Characteristics And Ecological Risks Of Water Environment In An Antimony Mining Area In Guizhou

Abstract:Guizhou Province is one of the most important antimony industrial base in China,and antimony ore contains many heavy metal elements,those heavy metals emitted from antimony mining and smelting will have negative impacts on the ecological environment and human health.With the more and more frequent and large-scale exploitation and utilization of antimony ore resources in recent years,heavy metals pollution especially antimony pollution in the antimony mining area has been more and more serious,it have potential threat to people who lived in the mining and the surrounding watershed area.Therefore,it is important to research pollution characteristics of the antimony mining area to improve mining water environment.On April 1^st to April 15^th,2016,45 water samples and 45 sediment samples were collected of mining wastewater,upstream and downstream water along the antimony mine in Guizhou,respectively.the pH value,conductivity were analyzed,and the mass concentration of heavy metals As,Hg and Sb in water or sediment samples were analyzed,ecological risks of heavy metals in water sediments samples were assessed by using geo-accumulation index,potential ecological risk index and Nemerow multi-factor index method,respectively.The main results showed that:（1）During the sampling period,the pH value and the conductivity of45 water samples followed the order of mine wastewater>mine downstream water>mine upstream water.The pH mean value of the mine wastewater was 3.28,which was severe acidic water,while the pH mean value of the downstream water samples and the downstream water samples along the mine area was 7.36 and 6.36,respectively,which was close to neutral water.The water conductivities of three sampling sites were high,it will be beneficial to release heavy metals from minerals in wastewater.（2）The obvious pollution characteristics of heavy metals As,Hg and Sb in water samples at three sampling sites were showed,the heavy metals pollution followed the order of mine wastewater>mine downstream water>mine upstream water,and the heavy metal Sb>As>Hg.The heavy metal Hg and Sb in water all exceeded the limit values of National Surface Water Environmental Quality Standard and Integrated Wastewater Discharge Standard,but heavy metal As in water lower than the standard limit value.（3）The mass concentrations of heavy metals As,Hg and Sb in the sediments samples were all higher than water samples at three sampling sites,which indicated that the heavy metals of water environment along the antimony mining area were more easily deposited and enriched in the solid phase,and pollution level of heavy metals in the sediments samples was the same as water samples.（4）The geo-accumulation index results showed that the geo-accumulation index of heavy metals in mine wastewater followed the order of Sb>As>Hg,and the geo-accumulation index of heavy metal in the sediment in downstream and upstream water along the mine area followed the order of Sb>Hg>As.（5）The Potential ecological risk index results showed that the heavy metals in the mine wastewater residue belonged to heavy pollution level,the heavy metals in sediments of upstream water belonged to light pollution level,and the heavy metals in sediments of downstream water belonged to moderate pollution level.（6）The Nemerow multi-factor index results showed that the single factor pollution index of sediment in mine wastewater,upstream and downstream water samples all followed the order of Sb>As>Hg,and the comprehensive pollution index of heavy metal Sb in sediments at three sampling sites were high than 3.0,which belonged to serious pollution level.