南渡江流域农业表土中草甘膦及代谢物氨甲基膦酸的残留特征及生态风险评估

Residual characteristics and ecological risks of glyphosate and aminomethylphosphonic acid residues in surface soils from Nandu River Basin,China

[目的]研究海南典型稻菜轮作区域——南渡江流域农业表土中草甘膦(Gly)及其主要代谢产物氨甲基膦酸(AMPA)的残留特征及其潜在生态风险。[方法]于2021年11月和2022年3月共采集72份表土样品,分析表土中Gly和AMPA残留特征,利用冗余分析识别关键影响因素,采用风险商值(RQ)法对2者的慢性生态风险进行评估。[结果]Gly和AMPA残留浓度为2.5~8402.4、47.3~5909.4 ng/g,2者检出率超过90%,2者总浓度范围为47.3~11 273.7 ng/g;Gly和AMPA具有显著的空间分布特征,呈现上游>下游>中游,且3月>11月。冗余分析揭示,Gly和AMPA残留与土壤中有机质(OM)、铁/铝氧化物呈现正相关,而与土壤中pH呈负相关。生态风险评估显示,对于蚯蚓,Gly、AMPA有37.4%~70.8%的表土超过慢性生态风险,且2者总风险有79.2%的土壤呈RQ≥0.1,而对于土壤跳虫生态风险较小。[结论]研究区域表层土壤中Gly和AMPA普遍残留,残留水平较高,且对土壤蚯蚓有中/高生态风险,因此需要关注土壤中Gly的生态风险。

[Aims]The residual characteristics and ecological risks of glyphosate(Gly)and its main metabolite aminomethylphosphonic acid(AMPA)were assessed in agricultural topsoil from Nandu River Basin.[Methods]A total of 72 surface soil samples were collected in November 2021 and March 2022.Then,the occurrence of Gly and AMPA in soil samples were analyzed,and also their key influencing factors were identified by redundancy analysis.Meanwhile,the chronic ecological risks of Gly and AMPA were evaluated by risk quotient(RQ)method.[Results]The concentrations of Gly and AMPA were 2.5-8402.4 and 47.3-5909.4 ng/g,with the detection frequency of>90%.The total concentration(Gly and AMPA)was 47.3-11273.7 ng/g;the distributions of Gly and AMPA have significant spatial characteristics with upstream>downstream>midstream,and March>November.The redundancy analysis indicated that the residual characteristics of Gly and AMPA were positively correlated with organic matter(OM)and iron/aluminum oxides(Fe/Al oxides)in surface soils,but negatively correlated with soil pH.The ecological risk assessment showed that there were 37.4%-70.8%of the topsoil exceeds the chronic ecological risk(RQ≥0.1)to earthworm(Eisenia foetida),and the total risks of Gly and AMPA presented higher ecological risk with RQ≥0.1 in79.2%soil samples.However,the ecological risk of Gly and AMPA to Collembola(Folsomia candida)can be ignored.[Conclusions]The residue of Gly and AMPA are prevailing occurred in the surface soils from Nandu River Basin,and its residue levels is higher than that in other regions;meanwhile,the medium or high ecological risks to soil earthworm were observed in the soil.Therefore,the more attention should be paid to residue and risks of Gly in soil.