基于特定源风险评估模型的小麦籽粒铅超标风险预测

系统分析重金属铅（Pb）在"源-土壤-小麦"传输途径中的累积特征是小麦Pb污染防治的关键.以河南省济源市为例,在区域调查的基础上,耦合正定矩阵因子分解法、Freundlich回归方程和Monte Carlo随机模拟方法,构建特定源风险评估模型（SRAM）,预测不同场景下小麦籽粒Pb累积风险,并结合空间分析方法对区域污染防治措施进行评估和优化.结果表明,大气沉降和磷肥应用是区域农田土壤Pb污染的主要来源,贡献了小麦籽粒Pb超标累积的29.0%.土壤pH和阳离子交换量（CEC）是影响小麦籽粒Pb累积的关键土壤因子.在受大气污染影响显著的高风险区域（研究区西北和西部）,通过相关措施提升土壤阳离子交换量（~20 cmol·kg^-1）可将大气沉降源导致小麦籽粒Pb超标风险从10.5%显著降低至2.39%.

Assessing the Lead Accumulation Risks of Wheat Grain by Developing a Source-Specific Accumulation Risk Assessment Model

Characterizing the lead (Pb) transfer in the "source-soil-wheat" chain is of great importance for the prevention and control of the Pb accumulation risk in wheat grain harvested from the croplands of China. In this study, we used the Jiyuan City, northern China, as a case study to investigate the influence of contamination sources and soil factors on the accumulation of Pb in wheat grain. A site-specific source risk assessment model (SRAM), coupling the positive matrix factorization model, Freundlich-type function, and the Monte Carlo simulation method, was developed to estimate the risk of Pb accumulation in wheat grain harvested from different scenarios. Based on the results of the spatial analysis, the effectiveness and potential risk of the control measures applied in the study area was also evaluated. Atmospheric deposition and phosphate fertilizer application were identified as major sources contributing to 29.0% of the Pb accumulations in wheat grain. Soil pH and cation-exchange capacity (CEC) were the primary causative factors affecting the Pb accumulation in wheat grain. Cropping wheat in the high Pb continuation risk areas (western and northwestern areas) of Jiyuan City caused a 10.5% likelihood of Pb to accumulate above the China food standard limit of 0.2 mg·kg^-1 (DW). This risk was significantly decreased to 2.39% when the CEC levels of affected soils was improved to 20 cmol·kg^-1 and above.