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Abstract
Wetlands are vital ecosystems vulnerable to threats such as metal contamination. Microorganisms have shown to mediate metal fate and bioavailability, but the influence of environmental factors—particularly light exposure—on these interactions remains unclear. Previous works have shown that light can influence these communities, however its consequences for metal dynamics is understudied. We conducted a microcosm experiment using two wetlands—a constructed site and a natural depressional wetland at the Savannah River Site (Aiken, SC). Microbial communities were acclimated under light and dark conditions, with copper added at the midway point. We assessed how light influenced microbial-driven copper transport and distribution between sediment and water. Our findings show that light significantly alters microbial community alpha diversity and membership, promoting copper retention in sediments under ambient conditions but lessening it under elevated copper stress. These results highlight abiotic factors like light shape microbial processes, informing strategies for wetland conservation and metal contamination management.