典型地质高背景区土壤硒-镉迁移累积特征及其生物有效性  

Characteristics of Soil Selenium-cadmium Migration and Accumulation and Its Bioeffectiveness in Typical Geological High Background Area

作　　者：周亚龙[1,2,3] 彭敏 杨志斌[1] 陈杰 王成文[1] 韩伟 ZHOU Ya-long;PENG Min;YANG Zhi-bin;CHEN Jie;WANG Cheng-wen;HAN Wei(Institute of Geophysical&Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang 065000,China;Research Center of Geochemical Survey and Assessment on Land Quality,China Geological Survey,Langfang 065000,China;Key Laboratory of Geochemical Cycling of Carbon and Mercury in the Earth's Critical Zone,Chinese Academy of Geological Sciences,Langfang 065000,China;Yunnan Institute of Geological Survey,Kunming 650216,China)

机构地区：[1]中国地质科学院地球物理地球化学勘查研究所,廊坊065000 [2]中国地质调查局土地质量地球化学调查评价研究中心,廊坊065000 [3]中国地质科学院地球表层碳汞地球化学循环重点实验室,廊坊065000 [4]云南省地质调查院,昆明650216

出　　处：《环境科学》2024年第8期4860-4869,共10页Environmental Science

基　　金：中国地质调查局地调项目(DD20189123,DD20221770)。

摘　　要：地质高背景区土壤中普遍存在的硒-镉(Se-Cd)共生现象直接影响富Se土地资源的安全利用.为探究西南地质高背景区土壤-作物系统Se-Cd迁移累积特征及生物有效性,实现地质高背景区天然富Se土地资源的安全利用,系统采集分析84件农作物(玉米)及其配套根系土壤样品中Se-Cd含量及理化性质,采用地统计、生物富集因子及地理探测器等分析方法,开展土壤-作物系统中Se-Cd累积特征、影响因素及生物有效性评价.结果表明,研究区土壤Se-Cd含量显著高于全国和云南省土壤背景值,受地质背景、成土过程中次生富集作用和农业活动的影响呈现不同程度的积累富集特征,根系土壤Se地累积指数等级为无富集到轻微富集等级,赋存形态以残渣态为主;土壤Cd地累积指数等级以中度污染等级为主,赋存形态以残渣态和铁锰结合态为主.作物籽实富Se率达98.8%(DB 50/T 524-2013),生物富集因子均值为5.8%;作物籽实Cd含量超标率仅1.19%(GB 2762-2022),Cd生物富集因子平均值为2.11%,作物籽粒Cd的生态风险相对较低.地质背景成因的Se-Cd共生区,土壤弱碱性环境能有效降低区内作物籽实Cd的生物有效性,土壤富Se对于作物吸收Cd有一定抑制效果.相关分析显示,土壤-作物系统中Se和Cd从土壤向作物籽实的迁移累积受元素赋存形态和土壤理化性质(pH)等因素的影响,同时,土壤-作物系统中Se与Cd相互之间也存在一定的拮抗作用.The prevalence of selenium-cadmium(Se-Cd)symbiosis in soils of geologically high background areas directly affects the safe utilization of Se-rich land resources.To investigate the migration and accumulation characteristics and bio-effectiveness of Se-Cd in the soil-crop system in typical geological high background areas of Southwest China and to realize the safe use of natural Se-rich land resources in geological high background areas,we collected 84 samples of agricultural crops(maize)and their supporting root systems and analyzed the Se-Cd content and physicochemical properties.Se-Cd accumulation characteristics,influencing factors,and bio-effectiveness of the soil-crop system were evaluated using geostatistics,bioenrichment factors,and geographic detectors.The results showed that the Se-Cd content in the study area was significantly higher than the background value of the soil in the whole country and in Yunnan Province.Influenced by the geological background,secondary enrichment in the process of soil formation,and agricultural activities,the accumulation and enrichment characteristics of Se in the root soil varied from no enrichment to slightly enriched,and the occurrence form was dominated by the residue state.The accumulation index of soil Cd was mainly in the medium pollution level,and the occurrence form was mainly in the residual state and the combined state of iron and manganese.The Se-enrichment rate of crop seeds reached 98.8%(DB 50/T 524-2013 standard),and the average value of bioconcentration factor was 5.8%.The exceeding rate of Cd content in crop seeds was only 1.19%(GB 2762-2022 standard),and the average value of Cd bioconcentration factor was 2.11%,so the ecological risk of heavy metal Cd in crop seeds was relatively low.In the Se-Cd symbiosis area under geological background,the weak alkaline environment of the soil could effectively reduce the bioavailability of Cd in crop seeds,and the Serich soil could inhibit the uptake of Cd by the crops to a certain extent.Correlation analysis showed th

关 键 词：硒-镉(Se-Cd) 土壤-作物系统 生物有效性 拮抗作用 地质高背景 

分 类 号：X171.5[环境科学与工程—环境科学]