Loss of soil organic matter in the mining landscape and its implication to climate change

Environmental contamination due to mines disturbs biological and physio-chemical properties of the soil. Literature available discussing environmental contamination and physical disturbances (waste dumps, loss of vegetation, and quarry sites) due to mines was critically evaluated to understand the implication of mines on soil organic matter. The factors responsible for organic matter (OM) degradation are divided into two categories, i.e., major (direct) and minor (indirect). The impacts due to major factors (decrease in OM at the quarry and waste dumping sites) in OM degradation are easy to quantify and directly caused by mines. The conversion of fertile land into quarry and waste dumping sites lead to loss of soil carbon and imbalances the ecosystem structure. The lack of nutrients and organic matter hinders the revegetation process of waste dump sites. The role of minor factors is not easy to quantify (reduction of OM due to land use and land cover change, depletion of water resources, heavy metal contamination, etc.) and indirectly impacts the OM degradation. The heavy metal contamination of neighboring soil retards the growth of plants and decreases the OM turnover. The soil erosion, loss of agricultural lands, deforestation, loss of soil moisture, depletion of water resources, decrease in microbial activities, and land subsidence in the mining region indirectly contribute to OM degradation. The degradation or release of carbon stored in the soil increases CO2 in the atmosphere contributing significantly to climate change. Mines spread in 57,277 km2 across the world and in India mine wasteland covers 2256 km2 of area. The wider spread of mines suggests that the degradation of OM and its contribution to climate change is in significant quantity at the global level. Further research on the degradation of organic carbon in the vicinity of mines and its contribution to climate change is recommended.