【摘要】 本研究旨在探明粤北典型工矿区农田土壤中镉(Cd)、铅(Pb)污染的空间分布特征与风险水平，构建以“总量—形态—生物有效性”为核心的评价框架，为区域土壤重金属污染的有效管控与修复提供科学依据。以粤北典型工矿业周边的特定农田区域为研究对象，通过调查采样和实验室分析，测定了土壤中Cd和Pb的总含量及其化学形态，评估其污染程度、风险等级及生物有效性。结果表明：（1）Cd和Pb的含量和各项评价指标均呈现较强的空间变异性，2种元素高值区的空间分布差异明显，表明其污染来源各不相同；其中，Cd元素呈现明显的点源污染特征。（2）Cd元素的潜在生态风险指数较高，而Pb元素的单因子指数和潜在生态风险指数结果均为无污染；而Cd的风险评估编码法(RAC)和次生相与原生相比值法(RSP)评估结果均为高度污染，Pb的RAC评估结果以轻度和中度风险为主，但其RSP结果为高度污染；基于重金属形态的生物有效性评价所判定的污染等级高于基于重金属总量评价的污染等级。研究区土壤以酸性为主，可以提高Cd的生物有效性，从而导致其存在重度污染风险；虽然Pb的总量评价结果显示相对安全，但其潜在生态威胁仍突出。因此，建议优先治理Cd污染，并加强对Pb的长期监测，以降低农田生态系统遭受复合污染的风险。更多还原

【Abstract】 This study investigated the spatial distribution and risk levels of cadmium(Cd) and lead(Pb)contamination in farmland soils within a typical industrial and mining area of northern Guangdong. An evaluation framework centered on “total content-chemical speciation-bioavailability” was constructed to provide a scientific basis for regional soil heavy metal pollution control and remediation. Taking the specific farmland area around typical industrial and mining industries in northern Guangdong as the research object,field sampling and laboratory analyses were conducted to determine the total concentrations and chemical speciation of Cd and Pb. The contamination degree, ecological risk, and bioavailability were systematically assessed. The results showed that:(1) both the contents and evaluation indices of Cd and Pb exhibit strong spatial variability. The spatial distributions of high-concentration areas differ between the two elements,indicating distinct pollution sources. Cd, in particular, displays significant point-source pollution characteristics.(2) Cd showed a high level according to the potential ecological risk index, whereas Pb was classified as uncontaminated based on both the single-factor index and the potential ecological risk index.However, the risk assessment code(RAC) and reduced partition index(RSP) evaluations for Cd both indicated high contamination levels. For Pb, RAC results suggested mainly low to moderate risk, while its RSP result indicated high contamination. The pollution grades derived from bioavailability-based assessment(using chemical speciation) were higher than those based on total heavy metal content. The soils in the study area were predominantly acidic, which could enhance Cd bioavailability and lead to a high contamination risk. Although Pb was considered safe based on total content evaluation, its potential ecological threat remained significant.Priority should be given to the remediation of Cd, while long-term monitoring of Pb should be strengthened to mitigate the composite pollution risk in the farmland ecosystem.更多还原