渤海沉积物中氧化铁的异化还原特征

The Characteristics of Microbial Iron Reduction in Marine Sediments from Bohai Bay

采用厌氧泥浆培养试验,通过对体系中Fe（Ⅱ）含量变化测定,明确了不同海区沉积物样品中Fe（Ⅲ）的厌氧还原特征。结果表明,不同采样位置的沉积物中Fe（Ⅲ）的还原潜势存在一定差异,除S17及S7样点外其他样品的Fe（Ⅱ）生成量都在3~5 mg.g-1之间,说明来自于不同位置的沉积物本身所含的可还原氧化铁数量及水环境对铁还原的影响不同。海河及大沽排污河河口的Ⅳ类水质海区沉积物中Fe（Ⅲ）还原能力最为强烈,在大港北排河及子牙新河的排海口Fe（Ⅲ）还原亦较高。距离海岸较远的Ⅰ类水质海区沉积物中Fe（Ⅲ）还原能力较弱。通过Logistic模型拟合和方差分析可以看出,Ⅰ类和Ⅱ类海区的Fe（Ⅱ）的最大累积量（a）没有显著差异,而与Ⅲ类和Ⅳ类海区差异达到极显著水平;Fe（Ⅱ）的累积速率常数（k）在Ⅰ、Ⅱ、Ⅲ和Ⅳ类水质海区没有显著的差异,但在最大反应速率（Vma）x上却反映出区别,其中Ⅱ和Ⅲ类水质海区的差异不明显,而与Ⅰ和Ⅳ类水质海区呈现极显著的差异。Fe（Ⅱ）的最大累积量（a）与NO3--N浓度呈显著的负相关关系,相关系数达到-0.834 5,表明NO3-与Fe（Ⅲ）是沉积物中相互竞争的电子受体。

Characteristics of dissimilatory Fe（Ⅲ）reduction in marine sediments with different water qualities are important to understand en-vironmental impacts on microbial iron reduction process and to reveal the mechanism of microbial remediation.Here,anaerobic slurry incu-bation experiments were conducted to define the characteristics of anaerobic Fe（Ⅲ）reducing in sediment samples from different marine re-gions by measuring the changes of Fe（Ⅱ）concentrations.The results showed that Fe（Ⅲ）reduction potentials varied in different sediments.The amount of Fe（Ⅱ）ranges from 3 mg.g-1 to 5 mg.g-1 except sample S17 and S7.It was indicated that the amounts of iron oxide contained in different sediments varied and water quality impacted on iron reduction.The iron reduction in the sediments from Haihe river and Daku river estuaries with Grade Ⅳ water quality was the most intensive.The sediments from Dagang river and Ziya river estuaries had also high Fe（Ⅲ）reduction capacity.In contrast,Fe（Ⅲ）reduction process in sediments far away from coast with Grade I water quality was inconspicu-ous.The Logistic model fitting and variance analysis showed that no significant difference of Fe（Ⅱ）maximum accumulation（a）was found between Grade I and Grade Ⅱ marine sediments,whereas significant difference between Grade Ⅲ and Grade Ⅳ marine sediments existed.There was no significant difference among Grade Ⅰ,Ⅱ,Ⅲ and Ⅳ water quality in rate constant of Fe（Ⅱ）accumulation（k）.However,the maximum reaction rate（Vma）xwas another case,which showed that Grade Ⅱ and Ⅲ water quality had no diversity,but Grade Ⅰ and Ⅳ water quality presented extremely significant difference.There was a negative correlativity between Fe（Ⅱ）maximum accumulation（a）and NO3--N,whose correlation coefficient was-0.834 5.It was suggested that NO3-was a competing electron acceptor to Fe（Ⅲ）in sediments.