The environmental impact of Angouran mining on the regional aquifers; Iran

摘要

Angouran lead and zinc mines located in the southwest of Zanjan province (Mahneshan), is one of the world's largest lead and zincmines. Extraction method in this mine is staircase in order to receive critical mine materials which have produced so many waste material around the mine. Some of the sulfide ores accumulate in mine tailings due to low alloy and uneconomic extraction. When these sulfide ores react with the weather at ground level, they cause the generation of acidic drainage water and mobilityof heavy metals in Angouran mine tailings. According to the condition of the mine which is located in the upstream of the plain, progression of this trend cause that mobile heavy metals release into the Allahlooriver along with the existing runoff in the mine drainage basin and are widely spread by feeding the underground water table of the Angouran aquifer. As a result of seven-element concentration including: lead, zinc, cadmium, nickel, copper, chromium, and cobalt in drinking water of twenty villages and a city in two adjacent basins and analysis of the results of samples concentration by GIS package it was determined that the concentration of heavy metals in drinking water of the villages in the drainage basin is much higher than adjacent basinsthat have no connection with any mine drainage basin. Ultimately, it can be noted the high concentration of heavy metals in mine drainage basin is due to mining regardless to the environmental regulations. In order to eliminate this pollution, methods such as wastes insulation, creating purification basins and constructing artificial ponds are recommended in order to prevent entering of heavy metals to the environment.