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

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) de ciency 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 de ciency 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.

A review of soil pollution by potentially toxic elements and remediation strategies in copper mining areas in Iran

“…Firstly, excessive quantities of copper minerals, such as chalcopyrite, cuprite, covellite, chalcocite, and malachite, discharged into soil during mining activities. This is primarily caused by destructive mining processes and inadequate treatment of mineral waste residue and wastewater (Alizadeh et al 2024;Punia 2021). Cu-tailing dams also contribute significantly to Cu contamination of soil (Das and Maiti 2008).…”

“…Particularly, the process of PTE transportation in Cu mining area is directly influenced by wind direction and intensity (Punia 2021;Mulenga et al 2022). Furthermore, the distribution of PTE in soils associated with Cu mines was found to be affected by variables such as exploitation methods soil properties, and site use (Alizadeh et al 2024).…”

“…The application of plants to eliminate pollutants is an environmentally friendly method that does not disturb the ecosystem, as it does not adversely impact topsoil (Erickson & Pidlisnyuk 2021). The most important step to successfully use plant-based remediation for polluted soils and mine tailings is the selection of appropriate hyperaccumulators (van der Ent et al 2024). Hyperaccumulator plants have the potential to extract, accumulate, and endure elevated concentrations of PTEs.…”

“…These plants can accumulate PTEs in their roots and shoots, by phytostabilization and phytoextraction, respectively. Phytostabilization comprises the immobilization of contaminants within the soil, whereas phytoextraction encompasses the utilization of plants to extract/remove contaminants from polluted soil (Erickson & Pidlisnyuk 2021;van der Ent et al 2024). However, it is important to take into account that mining areas are not conducive for vegetation growth, due to issues such as low water availability, unfavorable pH, high concentrations of harmful PTEs, and low levels of organic matter and nutrients (Borbón-Palomares et al 2024).…”