Abstract
The water-soluble heavy metal ions in contaminated soil may enter aquatic ecosystem through runoff, thus causing negative impact on the water environment. In this study, a two-year in situ experiment was carried out to explore an effective way to reduce the runoff erosion and water-soluble copper (Cu) and cadmium (Cd) in a contaminated soil (Cu: 1,148 mg kg−1, Cd: 1.31 mg kg−1) near a large Cu smelter. We evaluated the ability to influence soil properties by four Cu-tolerance plant species (Pennisetum sp., Elsholtzia splendens, Vetiveria zizanioides, Setaria pumila) grown in a contaminated acidic soil amended with lime. The results show that the addition of lime can significantly reduce the exchangeable fraction (EXC) of Cu and Cd in soil (81.1–85.6% and 46.3–55.9%, respectively). Plant species cannot change the fraction distributions of Cu and Cd in the lime-amended soils, but they can reduce the runoff generation by 8.39–77.0%. Although water-soluble Cu concentrations in the runoff were not significantly differed and water-soluble Cd cannot be detected among the four plant species, the combined remediation can significantly reduce 35.9–63.4% of Cu erosion to aquatic ecosystem, following the order: Pennisetum sp. > Elsholtzia splendens > Vetiveria zizanioides > Setaria pumila. The implication of this study would provide valuable insights for contaminated soil management and risk reduction in the Cu and Cd contaminated regions.
Highlights
Increasing anthropogenic activities such as smelting and irrigation using waste water and atmospheric deposition have caused severe heavy metal contamination in soil around the world (Xu X et al, 2018)
This study explores the various effects of the combined remediation of lime and Pennisetum sp., Elsholtzia splendens, Vetiveria zizanioides on speciation and availability of heavy metals in soil and runoff and concentration of heavy metals in runoff
The highest soil organic carbon content in 2014 was found in the lime–Pennisetum sp (LP) treatment (19.1 g kg−1). This result might be related to three factors: first, vegetation restoration in soil erosion areas increased vegetation coverage and reduced soil erosion and nutrient loss (Tao et al, 2020); at the same time, the presence of plant residues, roots and root exudates increased the input of organic matter to the soil (Lu et al, 2019); last, after the combined remediation, the changes of microbial community structure and function related to organic carbon turnover might affect the accumulation of organic carbon (Zhao et al, 2015)
Summary
Increasing anthropogenic activities such as smelting and irrigation using waste water and atmospheric deposition have caused severe heavy metal contamination in soil around the world (Xu X et al, 2018). Soil erosion has been a worldwide land degradation process and a Remediation Effects on Metals and Runoff serious threat to the sustainability of agriculture (Borrelli et al, 2015; Wang R et al, 2016; Wang Y et al, 2016). In China, 28.3% of the total soil loss occurs on agricultural lands, which account for only 6.8% of the total area of soil loss (MWR, 2007) (Li et al, 2014). The researches show that heavy metals mainly accumulate in the surface layer of soil and heavy metals in the surface layer can enter the surface runoff with the process of soil erosion (Devi and Bhattacharyy, 2018). The migration of heavy metals with surface runoff will cause the expansion of heavy metal pollution area (Ouyang et al, 2018b)
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