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<p>Heavy metal pollution in soils poses significant environmental and health risks. Identifying the potential sources and sinks of heavy metals in farmland is essential for the effective management and control of agricultural soil pollution. In this study, a two-year field mass balance-based inventory analysis across a gradient of soil pollution in a rice–wheat rotation system was conducted. The aim was to ascertain the primary input and output pathways of metals (Cd, Pb, Cu, and Zn) and to predict future trends in soil metal concentrations. The results showed that, at both polluted and background sites, the primary inputs of heavy metals were derived from atmospheric deposition, accounting for 55%–99% of the total input fluxes. Furthermore, dry deposition was identified as the predominant source of atmospheric inputs in the study area, contributing 57%–90% of atmospheric deposition inputs. The metal outputs were primarily from crop harvesting, with straw removal (including stems and leaves) contributing 46%–83% of total outputs. Compared to straw return mode, straw removal significantly reduced the accumulation of heavy metals in soils. The annual balance demonstrated that Cd and Pb were the metals of priority concern in the study area. Additionally, for Cd, a net decrease in heavily polluted soil occurred under phytoextraction using the hyperaccumulator <i>Sedum plumbizincicola</i>, indicating that phytoremediation via <i>Sedum plumbizincicola</i> remained effective in near-neutral soils in the present area. The insights gained from this study provided a comprehensive understanding of the net input metals in rice–wheat rotation areas under different modes of plant harvesting. Our study highlights the importance of reducing the input fluxes from atmospheric deposition sources, as well as implementing phytoextraction (through crop straw removal and hyperaccumulators) to protect the soil environment in rice–wheat rotation areas.</p> Graphical Abstract <p>Highlights</p> <p>- Input and output inventory of heavy metals in rice-wheat rotation area were studied.</p> <p>- Atmospheric deposition was the primary source of heavy metal input.</p> <p>- Crop harvesting, particularly straw removal, was main output pathway of soil metals.</p> <p>- Mass balance indicated Cd and Pb be the metals of priority concern in study area.</p> <p>- Phytoextraction using hyperaccumulators can reduce the environmental risk of Cd.</p> <p></p>

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Mass Balance-Based Inventory of Heavy Metal Inputs and Outputs of Agricultural Soils in a Rice–Wheat Rotation Area, China: A Two-Year Field Experiment

  • 期刊论文

  • 发表日期：

    2025年11月5日

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  • Hailong Liu,
  • Xiuting Rong,
  • Haotian Wang,
  • Hu Wang,
  • Huan Zhao,
  • Ruizhi Xia,
  • Xiaozhi Wang,
  • Min Li

摘要

Heavy metal pollution in soils poses significant environmental and health risks. Identifying the potential sources and sinks of heavy metals in farmland is essential for the effective management and control of agricultural soil pollution. In this study, a two-year field mass balance-based inventory analysis across a gradient of soil pollution in a rice–wheat rotation system was conducted. The aim was to ascertain the primary input and output pathways of metals (Cd, Pb, Cu, and Zn) and to predict future trends in soil metal concentrations. The results showed that, at both polluted and background sites, the primary inputs of heavy metals were derived from atmospheric deposition, accounting for 55%–99% of the total input fluxes. Furthermore, dry deposition was identified as the predominant source of atmospheric inputs in the study area, contributing 57%–90% of atmospheric deposition inputs. The metal outputs were primarily from crop harvesting, with straw removal (including stems and leaves) contributing 46%–83% of total outputs. Compared to straw return mode, straw removal significantly reduced the accumulation of heavy metals in soils. The annual balance demonstrated that Cd and Pb were the metals of priority concern in the study area. Additionally, for Cd, a net decrease in heavily polluted soil occurred under phytoextraction using the hyperaccumulator Sedum plumbizincicola, indicating that phytoremediation via Sedum plumbizincicola remained effective in near-neutral soils in the present area. The insights gained from this study provided a comprehensive understanding of the net input metals in rice–wheat rotation areas under different modes of plant harvesting. Our study highlights the importance of reducing the input fluxes from atmospheric deposition sources, as well as implementing phytoextraction (through crop straw removal and hyperaccumulators) to protect the soil environment in rice–wheat rotation areas.

Graphical Abstract

Highlights

- Input and output inventory of heavy metals in rice-wheat rotation area were studied.

- Atmospheric deposition was the primary source of heavy metal input.

- Crop harvesting, particularly straw removal, was main output pathway of soil metals.

- Mass balance indicated Cd and Pb be the metals of priority concern in study area.

- Phytoextraction using hyperaccumulators can reduce the environmental risk of Cd.