农用地土壤重金属锌的生态安全阈值研究

Soil ecological safety thresholds for zinc in agricultural land

土壤生态安全阈值是合理修订农用地土壤风险管控标准的重要基础.然而,现行农用地土壤锌(Zn)的风险筛选值(GB 15618—2018)缺乏对土壤生态风险的考虑.本研究通过调研国内外Zn陆生毒性研究,收集并筛选Zn的10%效应浓度(EC10),采用物种敏感性分布法(SSD)分别构建陆生植物/无脊椎动物的SSD模型和微生物生态过程的功能敏感分布模型(FSD),基于风险附加法推导农用地土壤重金属Zn的生态安全阈值.结果表明,土壤pH是影响陆生植物和无脊椎动物生态毒性的重要因素,对土壤生态过程指标无显著影响.6种SSD模型(Log-Normal、Log-Logistic、Log-Gumbel、Gamma、Weibull and BurrIII)均可成功拟合不同pH土壤条件下的毒性数据,基于最优SSD模型推导强酸性土壤(pH≤5.5)、酸性土壤(5.5<pH≤6.5)、中性土壤(6.5<pH≤7.5)和碱性土壤(pH>7.5)条件下农用地土壤Zn的生态安全阈值,分别为170、230、305和410 mg·kg^(-1).本研究可为后续我国农用地土壤风险管控标准的修订提供科学依据.

Soil ecological safety threshold is the significant foundation for establishment of soil screening values in agricultural land.However,current risk screening values for zinc(Zn)in agricultural land(GB 15618—2018)is derived without the consideration of soil ecological risk.In this work,we collected terrestrial toxicity data(10%effect concentration,EC10)of Zn from eco-toxicological database and the reported literature,based on which species sensitivity distribution(SSD)and function sensitivity distribution(FSD)were established for protecting plants,invertebrates and ecological functional processes mediated by soil microbial community.The results showed that soil pH was the most significant factors affecting Zn ecotoxicity for plant and invertebrates,while there was no significant impact on soil ecological processes.The SSD curves of EC10 in soils with different range of pH were well fitted by Log-Normal,Log-Logistic,Log-Gumbel,Gamma,Weibull and BurrIII,form which the corresponding soil ecological safety thresholds were derived.Soil ecological safety thresholds were 170,230,305 and 410 mg·kg^(-1) according to different soil pH,respectively.This study could provide scientific basis for revision of soil risk control standard in China.