• 关键词：痕量元素  吸附-解吸  pH  湿地  闽江河口

• 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

• 李晓
• 1. 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;2. 福建师范大学地理研究所, 福州 350007

• 孙志高
• 1. 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;2. 福建师范大学地理研究所, 福州 350007;3. 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

• 李亚瑾
• 1. 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;2. 福建师范大学地理研究所, 福州 350007

• 陈冰冰
• 1. 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;2. 福建师范大学地理研究所, 福州 350007

• 胡星云
• 1. 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;2. 福建师范大学地理研究所, 福州 350007

• 何涛
• 1. 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;2. 福建师范大学地理研究所, 福州 350007

• 张鹏飞
• 1. 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;2. 福建师范大学地理研究所, 福州 350007

• 摘要：选择闽江河口鳝鱼滩的芦苇湿地、短叶茳芏湿地及二者交错带湿地为对象，研究了湿地土壤痕量元素的吸附-解吸特征及其对pH值变化的响应.结果表明，3种湿地土壤对Cr⁶⁺、Ni²⁺和Cd²⁺的吸附能力及其对Cr⁶⁺和Ni²⁺的最大缓冲容量均表现为短叶茳芏湿地低于交错带湿地和芦苇湿地；对Cu²⁺和Zn²⁺的吸附能力和最大缓冲容量在0~30 cm土层均以芦苇湿地较高，而在30~60 cm土层以短叶茳芏湿地较高.导致3种湿地土壤对痕量元素吸附能力差异的原因主要与土壤颗粒组成和pH值的差异有关.Langmuir吸附等温方程可较好地拟合湿地土壤吸附Cr⁶⁺、Ni²⁺、Cu²⁺、Zn²⁺和Cd²⁺的热力学过程（R²≥0.82）.3种湿地土壤中Cr⁶⁺、Ni²⁺、Cu²⁺、Zn²⁺和Cd²⁺的解吸量均随吸附量的增加而增加，二者呈显著正相关（p<0.05或p<0.01），且其解吸过程均存在滞后现象，说明吸附过程的作用力较解吸过程强.随着pH值的增加，3种湿地土壤对Cr⁶⁺的吸附量均呈波动降低变化，对Ni²⁺、Cu²⁺、Zn²⁺和Cd²⁺的吸附量整体均呈增加趋势；而Cr⁶⁺、Cu²⁺、Zn²⁺和Cd²⁺的解吸量对pH值变化的响应与之相反.研究显示，在未来闽江河口硫酸型酸沉降发生频次增加的情况下，相对于短叶茳芏湿地，芦苇湿地和交错带湿地对Ni²⁺、Cu²⁺、Zn²⁺和Cd²⁺的吸附量将大幅降低，而解吸量将有所增加，说明Ni²⁺、Cu²⁺、Zn²⁺和Cd²⁺将更易游离于这两种湿地的土壤孔隙水中，进而可能增加其对植物或土壤生物的生态毒性风险.

• Abstract：To investigate the adsorption-desorption characteristic of micro-elements in soils of salt marshes in the Min River estuary and its response to pH variations, the Phragmites australis marsh (PA), Cyperus malaccensis marsh (CM) and ecotonal marsh (P. australis-C. malaccensis, PA-CM) were studied. Results showed that the adsorption capacities for Cr⁶⁺, Ni²⁺ and Cd²⁺ and the maximum buffer capacity (MBC) for Cr⁶⁺ and Ni²⁺in soils of CM were lower than those in soils of PA and PA-CM. Comparatively, the adsorption capacities and the MBC for Cu²⁺ and Zn²⁺ were higher in soils of PA at 0~30 cm depth, while those were higher in soils of CM at 30~60 cm depth. The differences in adsorption capacities for micro-elements among the three marsh soils were mainly dependent on their differences in grain composition and pH. The Langmuir adsorption isotherm equation could be used to better describe the adsorption thermodynamics for Cr⁶⁺, Ni²⁺, Cu²⁺, Zn²⁺ and Cd²⁺ (R²≥0.82). The desorption amounts of Cr⁶⁺, Ni²⁺, Cu²⁺, Zn²⁺ and Cd²⁺ in the three marsh soils generally increased with increasing adsorption amounts and significantly positive correlations occurred between them (p<0.05 or p<0.01). There was hysteresis in desorption, indicating that the force of adsorption process was stronger than that of desorption process. With increasing pH, the adsorption amounts of Cr⁶⁺ generally decreased while those of Ni²⁺, Cu²⁺, Zn²⁺ and Cd²⁺ increased, but the responses of desorption amounts for Cr⁶⁺, Cu²⁺, Zn²⁺ and Cd²⁺ to pH variations were just in opposite. This paper found that, as the frequency of sulfuric acid precipitation in the Min River estuary increased in future, the adsorption amounts of Ni²⁺, Cu²⁺, Zn²⁺ and Cd²⁺ in soils of PA and PA-CM would decrease significantly compared to CM while the desorption amounts would increase greatly, implying that Ni²⁺, Cu²⁺, Zn²⁺ and Cd²⁺ could be more easily desorbed from soils into pore-water in PA and PA-CM, which might increase their ecotoxicity risk to plants and soil organisms.

• Key words：micro-elements  adsorption-desorption  pH  marsh  Min River estuary

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