基于DGT和化学提取法研究浙西北地质高背景区土壤镉生物有效性  

Cadmium Bioavailability Based on Diffusive Gradients in Thin Films Technique and Conventional Chemical Extraction in High Geological Background Soil Area of Northwestern Zhejiang Province,China

作　　者：吴超[1,2] 孙彬彬 成晓梦[1,2] 刘冬 乔宇 贺灵 曾道明 WU Chao;SUN Binbin;CHENG Xiaomeng;LIU Dong;QIAO Yu;He Ling;ZENG Daoming(Key Laboratory of Geochemical Exploration,Ministry of Natural Resources,Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang 065000,China;UNESCO International Center on Global-scale Geochemistry,Langfang 065000,China;Shanxi Geological Survey Institute Co.,Ltd.,Taiyuan 030000,China)

机构地区：[1]自然资源部地球化学探测重点实验室,中国地质科学院地球物理地球化学勘查研究所,河北廊坊065000 [2]联合国教科文组织全球尺度地球化学国际研究中心,河北廊坊065000 [3]山西省地质调查院有限公司,山西太原030000

出　　处：《岩矿测试》2023年第4期823-838,共16页Rock and Mineral Analysis

基　　金：中国地质科学院地球物理地球化学勘查研究所中央财政科研项目结余资金项目(JY201905);中国地质科学院地球物理地球化学勘查研究所中央级公益性科研院所基本科研业务费专项资金资助项目(AS2022P03)。

摘　　要：地质高背景区相较于人类活动引起的土壤镉污染影响范围更广,在区域尺度上对生态系统和人类健康构成危害。土壤镉生物有效性是决定其生物可利用性、生物毒性的关键因素,因此探寻可行的土壤镉生物有效性评价方法对污染农用地安全利用和风险管控具有重要的理论和实际意义。DGT技术、单一提取法、连续提取法和土壤溶液法常用于测定土壤有效镉,但已有研究成果主要基于同种土地利用类型土壤的室内盆栽实验,难以代表自然污染土壤中的复杂情况。为探明各土壤重金属有效态提取技术对地质高背景区不同土地利用类型土壤Cd生物有效性评估效果,本文以浙江西北部土壤Cd高地质背景区水田土壤-水稻籽实和旱地土壤-小白菜样品为研究对象,实验应用DGT技术、单一提取法(0.01mol/L氯化钙提取)、连续提取法(七步连续提取)和土壤溶液法评价土壤中镉生物有效性。结果显示:①研究区水田和旱地土壤Cd平均含量分别为1.07mg/kg和0.73mg/kg,显著高于浙江和全国土壤平均水平,Cd的异常富集主要与浙西北地区广泛分布的黑色岩系有关。②相较于碳酸盐岩区,黑色岩系区土壤中Cd的生物有效组分占比较高,水田和旱地土壤Cd的活动系数(MF)高达59.9%和51.8%,Cd易在土壤-作物系统中发生迁移富集;③植物体内镉含量Cd-P与不同方法测定的有效镉含量均呈显著正相关,但Cd-P与DGT技术测定的有效镉含量相关性优于其他三种方法,水田土壤测得的有效Cd与水稻籽实相关关系:C_(soln)>C_(DGT)>C_(Cacl_(2))>C_(F_(1)+F_(2)+F_(3)),旱地土壤测得的有效Cd与小白菜相关关系:CDGT>C_(Cacl_(2))>C_(F_(1)+F_(2)+F_(3))>C_(soln)。综合比较不同土壤有效Cd测定方法的优缺点,DGT技术可以模拟植物体对Cd的动态吸收过程,更能准确地反映土壤Cd生物有效性,预测作物Cd含量水平,这与已有研究成果一致。此外,本文研究成果�BACKGROUND:High geochemical background has a greater impact on soil Cd pollution than human activities and is more detrimental to the environment and human health on a regional level.Research shows that the bioavailability of Cd in soil is the key factor to determine its bioavailability and biotoxicity,so it is of great theoretical and practical significance to find an effective method to evaluate the bioavailability of Cd in soil for the safe use and risk control of contaminated agricultural land.Single extraction methods with relatively simple operation and relatively low cost and sequential extraction methods providing morphological distribution feature information,are the most common methods for evaluation of heavy metals bioavailability in soil.In general,the available amount of soil heavy metals obtained by chemical extraction methods can better reflect the level of plant absorption than the total amount.However,chemical extraction methods have some drawbacks,including differences between the extraction principle and crop absorption process,a lack of universality in the extracts,redistribution and re-adsorption during the extraction process,and most notably,the failure to take into account dynamic changes in heavy metal concentrations in the root environment.Diffusive gradients in thin-films(DGT)technique is a new biomimetic in-situ sampling technique,which has been widely used to assess the bioavailability of various elements in soil,water,sediment and other environmental media in recent years.The process of DGT absorbing target elements is similar to plants absorption,which can better reflect bioavailability.However,existing research results using DGT to evaluate soil Cd pollution is mainly based on indoor pot experiments.Exogenous addition of heavy metals to contaminated soil not only has high bioavailability,but also reduces the sensitivity of soil pH and other factors to the bioavailability of heavy metals in soil,which does not accurately represent the complex situation in naturally contaminated soil.

关 键 词：地质高背景 黑色岩系 梯度扩散薄膜技术(DGT) 化学提取法 镉 生物有效性 

分 类 号：O614.242[理学—无机化学] S151.93[理学—化学]