• 关键词：重金属  吸附-解吸  酸沉降  湿地沉积物  闽江福州段

• 基金项目：国家自然科学基金面上项目（No. 41971128）；福建省“闽江学者奖励计划”项目

• 李亚瑾
• 福建师范大学湿润亚热带生态地理过程教育部重点实验室，福州 350007;福建师范大学地理研究所，福州 350007

• 孙志高
• 福建师范大学湿润亚热带生态地理过程教育部重点实验室，福州 350007;福建师范大学地理研究所，福州 350007;福建师范大学福建省亚热带资源与环境重点实验室，福州 350007

• 李晓
• 福建师范大学湿润亚热带生态地理过程教育部重点实验室，福州 350007;福建师范大学地理研究所，福州 350007

• 毛立
• 福建师范大学湿润亚热带生态地理过程教育部重点实验室，福州 350007;福建师范大学地理研究所，福州 350007

• 厉彦哲
• 福建师范大学湿润亚热带生态地理过程教育部重点实验室，福州 350007;福建师范大学地理研究所，福州 350007

• 摘要：选择闽江福州段为研究对象，通过采集淡水河段（A、B）、城市河段（C、D）和河口区（E、F）6个样点的沉积物柱样，探讨了湿地沉积物重金属的吸附-解吸特征及其对酸沉降变化的响应.结果表明，Langmuir吸附等温方程可较好地拟合不同河段湿地沉积物吸附4种重金属（Ni²⁺、Cu²⁺、Zn²⁺和Cd²⁺）的热力学过程（R²≥0.71）.不同样点对Ni²⁺、Cu²⁺、Zn²⁺和Cd²⁺的吸附能力整体以河口区最高，城市河段次之，淡水河段最低， 解吸能力则与之相反，这主要与沉积物颗粒组成（黏粒）及pH值的差异有关.从淡水河段至河口区（A~F），不同样点0~40 cm土层对Ni²⁺、Cu²⁺、Zn²⁺和Cd²⁺的解吸量均随吸附量的增加而升高.随着pH值的增加，Ni²⁺、Cu²⁺、Zn²⁺和Cd²⁺的吸附量整体均呈逐渐增加趋势，解吸量则与之相反.不同样点沉积物重金属吸附-解吸特征对酸沉降的响应并不明显，这主要与不同样点的空间异质性较大有关.研究发现，在未来闽江福州段 硫酸型酸沉降发生频次增加的情况下，A、B样点所处淡水河段的沉积物可能更有利于重金属离子游离于沉积物的孔隙水中，从而增加该河段重金属的污染及生物毒性风险.

• Abstract：To investigate the adsorption-desorption characteristic of heavy metals in marsh sediments in Fuzhou reach of the Min River and its response to acid precipitation， six columnar samples in freshwater segment （A and B）， urban segment （C and D） and estuarine segment （E and F） were studied. Results showed that the Langmuir adsorption isotherm equation could be used to better describe the adsorption thermodynamics for Ni²⁺， Cu²⁺， Zn²⁺ and Cd²⁺ （R²≥0.71） in marsh sediments of different segments. The adsorption capacities for Ni²⁺， Cu²⁺， Zn²⁺ and Cd²⁺ in sediments of freshwater segment were higher than those in urban and estuarine segments， while the desorption capacities were just in opposite， which were mainly dependent on their differences in grain composition （clay） and pH. From freshwater segment to the estuarine segment （A~F）， the desorption amounts of Ni²⁺， Cu²⁺， Zn²⁺ and Cd²⁺ in sediments （0~40 cm） of different sampling sites generally increased with increasing adsorption amounts. Moreover， with increasing pH values， the adsorption amounts of Ni²⁺， Cu²⁺， Zn²⁺ and Cd²⁺ generally increased， but the responses of desorption amounts to pH values were just in opposite. It was worth noting that the responses of adsorption-desorption characteristic of heavy metals in sediments of different sampling sites to acid deposition were not evident， which probably rested on the spatial heterogeneity of different sites. This paper found that， as the frequency of sulfuric acid precipitation in Fuzhou reach of the Min River increased in future， Ni²⁺， Cu²⁺， Zn²⁺ and Cd²⁺ could be more easily desorbed from sediments into pore-water in sites of A and B， which might increase their pollution and ecotoxicity risks in freshwater segment.

• Key words：heavy metals  adsorption-desorption  acid precipitation  marsh sediments  Fuzhou reaches of the Min River

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