Evaluation of effect of phytoremediation of heavy metal pollution in farmland soils around a lead-zinc mine, Southwest China

Abstract

Abstract Environmental pollution by heavy metals in mining areas is a major concern worldwide since it affects surrounding farmland soils as well as the food chain and human health. Phytoremediation is amongst the low cost and environment friendly method proposed to clean up heavy metals from contaminated soils. In this study, we investigate the farmland soils of the Sidi village in Xingping Town, Yangshuo County, Guilin City, Guangxi Zhuang Autonomous Region, which were contaminated by nearby abandoned lead-zinc mine. The contents of heavy metals (As, Cd, and Pb) in these soils have severely exceeded the threshold local values according to the China national standard GB15618-2018. It is therefore urgent to carry out effective remediation of soils polluted by heavy metals to ensure safety of crop production in farmland soils of this region. Hyperaccumulator plants and plant barrier were adopted to reduce the content of heavy metals in soils of slightly polluted areas. The contents of As, Cd, and Pb in soils of moderately polluted areas were reduced by using passivator combined with low heavy metal accumulation crops. Rotation of oilseed rape and oil sunflower has continuously prevented metal pollution in heavily polluted areas. After 15 months of remediation, the pH values of soils in all polluted areas were gradually changing from weakly acidic to near-neutral pH, which met the requirements for crop planting. This study provides a scientific reference to apply remediation methods for polluted soils by heavy metals for the restoration of ecological environment of farmland soils around lead-zinc mine.