区域农田土壤镉风险的机理式定量预测模型研究——以江苏省为例

大面积区域土壤风险的精准定量评价和预测一直是研究的热点和难点,以往经验式为主的模型在普适性上存在较大局限.基于土壤理化性质和热力学化学平衡的机理式多表面形态模型(Multi-surface Speciation Model,MSM)已在实验室和小区域尺度成功预测土壤Cd的溶出,但能否应用于更大区域的环境风险评价还未可知.基于此,本研究收集了3354个江苏省表层土壤Cd样品和155个含有理化性质的表层土壤剖面,利用图斑赋值方法得到3354个具有完整理化性质和全量Cd含量的土壤样品数据,在此基础上利用MSM预测各样品的有效态Cd含量,并根据江苏省典型区域MSM-Cd阈值开发了基于MSM的江苏省土壤Cd污染生态风险评价预警模型和敏感性模型,并绘制了江苏省土壤Cd污染风险现状图和土壤Cd敏感地图.结果表明,MSM-Cd比总Cd可更准确预测高污染地区和非污染区域,同时发现增加土壤pH是降低Cd生态风险的最有效途径,而pH是影响土壤Cd敏感度的最重要原因.研究表明,基于MSM的土壤Cd风险预测模型可实现区域土壤风险的精准定量化评估与预测,为土地质量管理和风险管理提供决策依据的实用技术支持.

Regional soil Cd risk assessment and prediction based on multi-surface speciation model: A case study in Jiangsu

The accurate assessment and prediction of soil risk in a large area has always been a hot and difficult research topic, while previous empirical models had limitations on application universality. The multi-surface speciation model (MSM) based on soil physical and chemical properties and thermodynamic chemical equilibrium has been successfully applied to the ecological risk assessment of soil Cd in lab and small area scale. However, whether it can be extended to a larger area is still unknown. In this study, 3354 surface soil Cd concentration samples and 155 surface soil profiles with physical and chemical properties in Jiangsu Province were collected. Data of 3354 soil samples with complete physical and chemical properties and Cd concentration were obtained by using the method of map spot assignment. Then MSM was used to predict the available metal concentration of each sample. According to the MSM-Cd threshold value of typical regions in Jiangsu Province, a soil Cd ecological risk assessment and early warning model based on SM was developed. Meanwhile, a soil Cd pollution risk sensitivity model was developed and a soil Cd sensitivity map was drawn. The results showed that MSM-Cd could accurately locate highly polluted areas and non-polluted areas compared with total Cd. Increasing soil pH was the most effective way to reduce the ecological risk of Cd, and low pH was the most important reason to affect Cd sensitivity. Results showed MSM-based risk assessment model can be used to accurately evaluate and predict soil Cd risk in regional area, providing a practical technical support for land quality management and risk management.