Effect of plant growth and organic matter improvement on substrate properties and microbial community structure in copper tailings

In the ecological remediation of copper tailings in high altitude area, there are some problems, such as little nutrient accumulation, lack of cultivated soil, and low temperature and drought climate, which is not conducive to plant growth. So far, little research has been done on soilless plant remediation of copper tailings in this area. In order to solve the difficulty of plant growth in this area and facilitate soilless plant remediation, in this study, fermented yak dung (YD) was utilized as an organic amendment to improve copper tailings to obtain a substrate suitable for plant growth. Subsequently, three indigenous plants were planted on the modified copper tailings substrate to achieve plant remediation. The study examined the effects of YD addition and plant growth on enhancing the physical and chemical properties, mineral structure weathering, and alterations in microbial community within copper tailings. The results showed that the addition of YD and plant growth remarkably lowered the pH and bioavailability of heavy metals in copper tailings, while enhancing nutrient content and promoting the conversion of primary minerals to secondary minerals. Additionally, the treatment improved the water stability of copper tailings, and significantly changed the microbial community and aggregation structure in copper tailings. These findings have revealed the underlying mechanism of organic modification and plant growth on alkaline copper tailings, thus providing important basis for the ecological engineering of copper tailings in high altitude areas.