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研究报告

朱文凤,仝川,罗敏,黄佳芳,刘育秀,余子贤,吴杰.模拟Fe (III)和盐水输入对闽江河口潮汐湿地沉积物及间隙水Fe和S含量和形态的影响[J].环境科学学报,2018,38(11):4411-4421

Effects of saltwater incursion and ferric iron enrichment on abundance and fractions of Fe and S in pore water and sediment of a tidal freshwater wetland in the Min River estuary

基金项目：国家自然科学基金（No.41371127，41501252）；福建省自然科学基金（No.2016J05097）；福建师范大学校级创新团队项目（No.IRTL1205）；福建省公益类项目（No.2015R1101029-7）；福州大学开放测试基金（No.2018T013）；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开放基金项目

罗敏
1. 福建师范大学地理科学学院, 福州 350116;2. 湿润亚热带生态-地理过程教育部重点实验室, 福州 350007;3. 福州大学环境与资源学院, 福州 350116

摘要：河口潮汐湿地沉积物电子受体和盐度的变化将对间隙水、沉积物的地球化学参数及有机碳厌氧矿化途径产生重要影响.本研究于闽江河口塔礁洲淡水野慈姑（Sagittaria trifolia L.）湿地原位施加人造海水及Fe （Ⅲ）溶液，模拟研究了盐水入侵及径流Fe （Ⅲ）浓度增强对河口潮汐湿地沉积物、间隙水的地球化学参数（溶解性CH₄、DOC、DOC∶DON、Fe²⁺和ΔSO₄^2-）和沉积物各形态固相铁（非硫Fe （Ⅱ）、无定形Fe （Ⅲ）、晶质Fe （Ⅲ）、FeS和FeS₂）含量的影响.结果表明，模拟盐水入侵及径流Fe （Ⅲ）浓度增强均可降低间隙水溶解性CH₄和DOC浓度，径流Fe （Ⅲ）浓度增强增加了非硫Fe （Ⅱ）和晶质Fe （Ⅲ）含量，盐水入侵可减小间隙水ΔSO₄^2-含量.间隙水ΔSO₄^2-与DOC、DOC∶DON、溶解性CH₄及Fe²⁺浓度相关.模拟盐水入侵及径流Fe （Ⅲ）浓度增强可分别促进硫酸盐异化还原和铁异化还原速率，同时减小间隙水CH₄浓度，改变河口潮汐湿地土壤有机质厌氧矿化优势途径.

Abstract：Increases in salinity and electron acceptors have a significant impact on pore water and sediment geochemistry and organic matter mineralization in tidal wetlands. In this study, artificial saltwater and Fe (Ⅲ) were applied to in situ mesocosms of the tidal freshwater Sagittaria trifolia L. wetland of the Min River Estuary. Pore water geochemistry, including dissolved CH₄, dissolved organic carbon (DOC), the ratio of DOC to dissolved organic nitrogen (DON), pore water Fe²⁺ and ΔSO₄^2-, and various species of solid Fe (non-sulfidic Fe(Ⅱ), amorphous Fe(Ⅲ), crystalline Fe(Ⅲ), FeS, and FeS₂) were analyzed to compare treatments between spring and summer. The results suggest that dissolved CH₄ and DOC were suppressed due to seasonal treatment using saltwater and Fe(Ⅲ). The addition of Fe(Ⅲ) increased non-sulfidic Fe(Ⅱ) and crystalline Fe(Ⅲ), whereas the addition of saltwater decreased pore water ΔSO₄^2-. The pore water ΔSO₄^2- values correlated with DOC, DOC:DON, Fe²⁺, and dissolved CH₄. The addition of Fe(Ⅲ) and saltwater may enhance microbial iron and sulfate respiration, respectively, as both concurrently inhibit methane production, thus shifting the pathway of organic mineralization.

Key words：iron reduction sulfate reduction methane production tidal freshwater marsh Min River Estuary