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Iron dynamics in a subtropical estuarine tidal marsh: effect of season and vegetation
Seasonal dynamics of microbial iron and sulfate reduction were examined using in situ vegetated and unvegetated mesocosms. In both types of mesocosms, sulfate reduction tracked seasonal temperature variations, while the inhibitory effect of increasing temperature on iron reduction was clear. The dominant organic carbon mineralization pathway changed from sulfate reduction in summer to iron reduction in winter in both types of mesocosm. The vegetated mesocosms had higher rates of iron and sulfate reduction compared with the unvegetated mesocosms. However, the vegetation reduced the relative importance of sulfate reduction in favor of iron reduction as the primary organic carbon mineralization pathway. When directly compared, temperature clearly had a more pronounced effect on the organic carbon mineralization pathway than the vegetation.