Soil contamination around porphyry copper mines; an example from a semi-arid climate

Abstract

Abstract Extraction and processing of metalliferous ores can cause severe disturbances and contamination in natural ecosystems but little known about such effects for copper mines in semi-arid areas of southwest Asia. This study was conducted on seven sites around Sungun Copper Mine area, northwest Iran. Electrical Conductivity (EC), pH, nitrogen, phosphorous, potassium, organic matter, soil texture along with 16 metal and metalloids concentrations were measured in 94 soil samples. Results showed that sites were distributed along a gradient of contamination from low contamination in natural hillsides to high contamination in Waste Rock Dump, Oxide Dump, alongside Pakhir and Sungun Rivers. Nutrient (N, K, Ca, Mg) deficiency occurred in disturbed sites. The main contaminant sources were Waste Rock Dump, mine pit drainage, and Oxide Dump. The results of Non-metric multidimensional scaling ordination showed elevated Cd, Zn, Fe, Cu, Pb, As, Mo, Mn, Co, S concentrations, high EC, and higher sand percentage in the sites affected by mine waste and acid mine drainage. Geo-Accumulation and Potential Ecological Risk Indices indicate that Pakhir riverside, Sungun riverside and Oxide Dump have severe to moderate levels of environmental risks. Positive correlations between some metal elements imply their common sources and similar reaction pathways could also be a reason for their similar geochemical behaviour in transport and deposition and their interdependence. Overall, the deficiency of organic matter nutrients along with the soil sandy texture in contaminated sites of Sungun Copper Mine are the main limiting factors in managing metal mobility and soil remediation.