arsenic and antimony co-contamination on sedimentary microbial communities in rivers with different pollution gradients Raw sequence reads. arsenic and antimony co-contamination on sedimentary microbial communities in rivers with different pollution gradients

Arsenic (As) and antimony (Sb) are both toxic metalloids that are of primary concern for human health. Mining activity has introduced elevated levels of arsenic and antimony into rivers and has increased the risks of drinking water contamination in China. Due to their mobility, the majority of the metalloids originating from mining activities are deposited in the river sediments. Thus, depending on various geochemical conditions, sediment could either be a sink or source for As and Sb in the water column. Microbes are key mediators for biogeochemical transformation and can both mobilize or precipitate As and Sb. To further understand the microbial community responses to As and Sb contamination, sediment samples with different contamination levels were collected from three rivers. The interaction between the microbial communities and As and Sb extractable fractions was correlated with statistical tools. The As extractable fractions were suggested to be more influential to the community composition than the Sb extractable fractions. A decline in community diversity was observed in heavily contaminated samples. Individual taxa, however, demonstrated various responses to contamination. Operational Taxonomic Units (OTUs) that were potentially involved in As and Sb metabolism, such as Anaerolinea, Sphingomonas, and Opitutus, were enriched in the heavily contaminated samples. In contrast, many keystone taxa, including members of the Hyphomicrobiaceae and Bradyrhizobiaceae families, were inhibited by metalloid contamination, which could further impair crucial environmental services provided by these members.