| 三峡水库典型消落带土壤DOM组分特征及其对有效态镉释放影响 |
| 摘要点击 1634 全文点击 1437 投稿时间：2022-03-04 修订日期：2022-04-10 |
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| 中文关键词 三峡水库(TGR) 消落带 溶解性有机质(DOM) 镉(Cd) 梯度扩散薄膜技术(DGT) 迁移释放 |
| 英文关键词 Three Gorges Reservoir (TGR) water level fluctuation zone dissolved organic matter (DOM) cadmium (Cd) diffusive gradients in thin films (DGT) migration and release |
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| 中文摘要 |
| 重金属镉（Cd）是三峡水库蓄水后消落带土壤中主要的重金属污染物之一.为研究三峡水库反季节调蓄条件下溶解性有机质（DOM）对有效态Cd在土壤固-液相间释放行为及其再补给过程的影响，以三峡水库香溪河消落带为研究对象，分别于2019年10月和2020年10月采集土壤样品，利用紫外-可见吸收光谱、三维荧光光谱技术和荧光区域积分法分析土壤DOM光谱特性，同时结合梯度扩散薄膜技术（DGT）和土壤扩散通量模型（DIFS）综合探究土壤有效态Cd及其释放动力学过程.此外，测定了消落带土壤基本理化特性以及土壤中Cd含量和赋存形态.结果表明，研究区土壤DOM以富里酸为主，腐殖质特征较弱，具有陆源为主和内源较弱的混合特征，与2019年相比，2020年土壤DOM中富里酸类物质占比更高；2019年和2020年土壤ω（Cd）平均值分别为（0.474±0.301） mg·kg-1和（0.249±0.058） mg·kg-1，土壤中Cd的赋存形态均以非残渣态为主；DGT测定结果显示2020年土壤中有效态Cd含量较2019年呈下降趋势，进一步通过DIFS模型拟合结果表明，土壤中Cd的吸附速率大于解吸速率，土壤对有效态Cd的再补给能力较弱，表明三峡消落带土壤中有效态Cd的潜在释放风险较低，低分子量DOM和DOM中富里酸类物质是抑制土壤中有效态Cd释放的重要因素.研究结果揭示了三峡水库水文情势变化下DOM对重金属Cd环境地球化学行为的影响，为三峡库区重金属污染防治提供科学理论依据. |
| 英文摘要 |
| Cadmium (Cd) is one of the main heavy metal pollutants in the water level fluctuation zone soils following the impoundment of the Three Gorges Reservoir (TGR). To investigate the influence of dissolved organic matter (DOM) on the release behavior and resupply process of labile-Cd in the soil solid and liquid interphase under the anti-seasonal regulation and storage mode of the TGR, soil samples were collected from the riparian soils along Xiangxi River in October 2019 and October 2020. The UV-visible absorption spectrum, three-dimensional fluorescence spectroscopy, and fluorescence regional integration (FRI) were conducted to analyze the spectral characteristics of DOM. The diffusive gradients in thin films technology (DGT) and DGT-induced fluxes in soils (DIFS) model were used to reveal the labile-Cd and its release kinetics. Further, the soil physical and chemical property, content, and occurrence form of Cd were also determined. The results showed that the DOM was dominated by fulvic acid, and the humification degree was low, the source of DOM was mainly input from the land, and the content of fulvic acid-like materials in the DOM was higher in 2020. The average contents of Cd in soils in 2019 and 2020 were (0.474±0.301) mg·kg-1 and (0.249±0.058) mg·kg-1, respectively, and the non-residual components of Cd were the dominant fraction in the soils. The DGT and DIFS model assay results showed that the content of labile-Cd in soils in 2020 was lower than that in 2019. The adsorption rate of Cd in soils was higher than the desorption rate, the soils had a weak ability to recharge labile-Cd, and the potential release risk of labile-Cd was low, mainly due to the potential inhibition of the release of labile-Cd in soils by low-molecular weight DOM and fulvic acid. These results revealed the influence of DOM on the environmental geochemical behavior of Cd under the change in hydrological situation of the TGR, providing a reference for the management of heavy metals in the TGR area. |
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