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Purpose <p>This study aims to simplify the complex relationship between cadmium (Cd) content in rice and its influencing factors by analyzing key factors and remediation costs to ensure the safety of rice production on Cd-contaminated farmlands.</p> Materials and methods <p>In the research area, five 400&#xa0;m² plots were established for passivation experiments, each with separate water inlets and outlets. Experimental units ranged from 5 to 18, with passivation material costs between 3,000 and 38,400 CNY/ha. Soil samples were collected using the plum blossom method, air-dried, and analyzed for pH, organic matter, nitrogen, phosphorus, potassium, and cadmium content. Mature rice samples were also collected to measure cadmium levels.</p> Results and discussion <p>At the 95% confidence level, the proportion of rice samples meeting the cadmium content standards ranged from 26.7% to 46.8%. The main influencing factors include soil available cadmium content (<i>R</i> = 0.15), soil pH (<i>R</i> = 0.231), and organic matter (<i>R</i> = 0.117). When rice Cd content ranges from 0.2 to 0.3&#xa0;mg/kg, low-cost remediation (3,000–6,000 CNY/ha) can achieve a compliance probability exceeding 95%, while costs exceeding 6,000 CNY/ha indicate over-remediation. For rice Cd levels between 0.3 and 0.4&#xa0;mg/kg, remediation costs of 6,000–9,000 CNY/ha are required to ensure a compliance rate ≥ 95%. The reduction efficiency of Cd content improves with increasing costs but shows no significant enhancement beyond 15,000 CNY/ha.</p> Conclusions <p>This study quantified the relationship between remediation costs and rice safety assurance. Results indicated that at a 95% confidence level, 26.7% to 46.8% of rice samples met Cd content standards post-treatment. Significant factors affecting compliance included soil acidity, pH, and organic matter, with remediation costs over 15,000 CNY/ha showing diminishing returns. It fitted the quantitative relationship between remediation cost and the reduction in Cd content in rice: <i>y</i> =-1.15 + 1.51 × (1-exp[-4 × 10<sup>−4</sup><i>x</i>]), x represents cost of contaminated soil remediation (CNY/ha), and y represents Cd content reduction in rice (mg/kg).</p>

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Critical factors and cost estimation for the immobilization of cadmium-contaminated paddy fields for rice safety

  • 期刊论文

  • 发表日期：

    2025年10月11日

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  • Shuqi Li,
  • Dasong Lin,
  • Lili Huo,
  • Bo Wu,
  • Lixia Sun,
  • Yi An,
  • Yuqing Xia

摘要

Purpose

This study aims to simplify the complex relationship between cadmium (Cd) content in rice and its influencing factors by analyzing key factors and remediation costs to ensure the safety of rice production on Cd-contaminated farmlands.

Materials and methods

In the research area, five 400 m² plots were established for passivation experiments, each with separate water inlets and outlets. Experimental units ranged from 5 to 18, with passivation material costs between 3,000 and 38,400 CNY/ha. Soil samples were collected using the plum blossom method, air-dried, and analyzed for pH, organic matter, nitrogen, phosphorus, potassium, and cadmium content. Mature rice samples were also collected to measure cadmium levels.

Results and discussion

At the 95% confidence level, the proportion of rice samples meeting the cadmium content standards ranged from 26.7% to 46.8%. The main influencing factors include soil available cadmium content (R = 0.15), soil pH (R = 0.231), and organic matter (R = 0.117). When rice Cd content ranges from 0.2 to 0.3 mg/kg, low-cost remediation (3,000–6,000 CNY/ha) can achieve a compliance probability exceeding 95%, while costs exceeding 6,000 CNY/ha indicate over-remediation. For rice Cd levels between 0.3 and 0.4 mg/kg, remediation costs of 6,000–9,000 CNY/ha are required to ensure a compliance rate ≥ 95%. The reduction efficiency of Cd content improves with increasing costs but shows no significant enhancement beyond 15,000 CNY/ha.

Conclusions

This study quantified the relationship between remediation costs and rice safety assurance. Results indicated that at a 95% confidence level, 26.7% to 46.8% of rice samples met Cd content standards post-treatment. Significant factors affecting compliance included soil acidity, pH, and organic matter, with remediation costs over 15,000 CNY/ha showing diminishing returns. It fitted the quantitative relationship between remediation cost and the reduction in Cd content in rice: y =-1.15 + 1.51 × (1-exp[-4 × 10−4x]), x represents cost of contaminated soil remediation (CNY/ha), and y represents Cd content reduction in rice (mg/kg).