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引用本文:吴松峻,汪旋,季秋忆,王明玥,赵艳萍,王国祥.太湖西岸典型区域沉积物的硫铁分布特征及环境意义.湖泊科学,2019,31(4):950-960. DOI:10.18307/2019.0408
WU Songjun,WANG Xuan,JI Qiuyi,WANG Mingyue,ZHAO Yanping,WANG Guoxiang.Iron-sulfur distribution and its environmental significance in three typical areas of western Lake Taihu. J. Lake Sci.2019,31(4):950-960. DOI:10.18307/2019.0408
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太湖西岸典型区域沉积物的硫铁分布特征及环境意义
吴松峻1,2, 汪旋1,2, 季秋忆1,2, 王明玥1,2, 赵艳萍1,3, 王国祥1,2
1.南京师范大学环境学院, 南京 210023;2.江苏省地理信息资源开发与利用协同创新中心, 江苏省环境演变与生态建设重点实验室, 江苏省水土环境生态修复工程实验室, 南京 210023;3.美国东北大学土木与环境学院, 马萨诸塞州 02115
摘要:
以太湖西岸聚藻区、清淤区和开阔水域3种典型区域为对象,对沉积物中硫铁的分布进行研究.结果显示,各区域沉积物中铁还原均比硫还原活跃,硫铁氧化还原菌的分布表明硫铁循环主要集中于0~15 cm表层沉积物.开阔水域未发现明显硫离子(dS2-)释放与酸性可挥发性硫化物(AVS)沉积,硫还原较弱;二价铁离子(dFe2+)平均浓度为dS2-的5.2倍,说明沉积物仍以铁还原为主导.清淤区硫酸盐还原菌(SRB)相对丰度与dS2-含量均为所有区域中最低,且未见明显dFe2+释放,表明清淤抑制了硫铁还原的进行.聚藻区表层沉积物SRB相对丰度达到2.7%,且出现dS2-和AVS的显著升高,说明沉积物中发生着强烈的微生物硫还原.在表层沉积物也出现了明显的dFe2+释放,反映出强烈的铁还原,但沉积物中铁还原菌(FeRB)的平均丰度仅为0.6%,这一数值与其他区域相似,显然无法解释聚藻区与其他区域巨大的dFe2+差异,因此微生物铁还原并不是铁还原的主要途径.考虑到硫铁化合物的沉积与Fe(Ⅲ)氧化物的消耗一致,沉积物中的铁还原是由ΣS2-诱导的化学铁还原主导.dFe2+平均浓度为dS2-的4.8倍,监测培养沉积物的dS2-、dFe2+变化所得的铁还原速率是硫还原速率的7.4倍,说明铁还原仍比硫还原活跃.但由于AVS的沉积对ΣS2-的消耗,真实硫还原速率应高于测量值.
关键词:  硫还原  化学铁还原  三价铁氧化物  聚藻区  清淤区  开阔水域  太湖
DOI:10.18307/2019.0408
分类号:
基金项目:国家水体污染控制与治理科技重大专项(2017ZX07203-003)和国家自然科学基金项目(41573061)联合资助.
Iron-sulfur distribution and its environmental significance in three typical areas of western Lake Taihu
WU Songjun1,2, WANG Xuan1,2, JI Qiuyi1,2, WANG Mingyue1,2, ZHAO Yanping1,3, WANG Guoxiang1,2
1.School of Environment, Nanjing Normal University, Nanjing 210023, P. R. China;2.Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Jiangsu Key Laboratory of Environmental Change and Ecological Construction, Jiangsu Engineering Lab of Water and Soil Eco-remediation, Nanjing 210023, P. R. China;3.Department of Civil and Environmental Engineering, Northeastern University, Boston, Massachusetts 02115, United States
Abstract:
Geochemical characteristic of sulfur and iron was investigated in three types of sediments including algae accumulated sediment, dredged sediment and sediment away from lake shore. It was found that iron reduction dominated in all sediments rather than sulfate reduction. Both reduction concentrated in 0-15 cm surface sediments according to the distribution of microorganisms of iron and sulfur species. Accumulation of dS2- and acid volatile sulfide(AVS)was not observed in sediment away from lake shore, indicating that sulfate reduction is minor. Iron reduction was more active than sulfate reduction as the mean concentration of dFe2+ was 5.2 folds of dS2-. Sulfate reducing bacteria (SRB) abundance and dS2- content in dredged sediments were the lowest and dFe2+ release was not found, suggesting the depressed iron and sulfate reduction by dredging. SRB abundance in algae accumulated sediment reached to 2.7% and intensive dS2- release and AVS deposition were found, indicating the strong sulfate reduction. Active iron reduction was also found with high dFe2+ concentration in algae accumulated sediment. However, the mean abundance of iron reducing bacteria (FeRB) was only 0.6%, which was similar to other sediments and was obviously not able to explain the huge difference of dFe2+ concentrations. Thus, microbial iron reduction was not the main pathway of iron reduction. Considering the corresponding dissolution of Fe(Ⅲ) oxides and deposition of iron sulfides, sulfide-mediated chemical iron reduction was the dominating pathway. The mean concentration of dFe2+ was 4.8 folds of dS2-, and iron reduction rate was 7.4 folds of sulfate reduction rate by monitoring dS2- and dFe2+ variations, suggesting iron reduction was more active than sulfate reduction. However, as AVS generation could consume dS2-, the real rate of sulfate reduction was higher than the measured rate. Transition of iron and sulfur cycling would cause various negative effects and even extreme cases including "dead zones" in marine and "black bloom" in freshwater lakes. Although similar phenomenon was only observed in algae accumulated sediment, concern should still be raised.
Key words:  Sulfate reduction  chemical iron reduction  Fe(Ⅲ) oxides  algae accumulated sediment  dredged sediment  sediment away from lake shore  Lake Taihu
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