Hydrogen-breathing bacteria quietly release arsenic into river sediments
Huang D, Sun X, Lin W, Lan X, Tan Z
Soil Health
If your garden well or community water source sits near old mining land, this hidden bacterial process could be steadily loading groundwater with toxic arsenic long after the mine itself is gone.
Scientists studying river mud near a mining site found bacteria that use hydrogen gas as fuel to convert solid, buried arsenic into a dissolved form that can leak into water. They traced this ability to specific microbes and found the genetic toolkit for it in about three-quarters of known arsenic-reducing bacteria, meaning this isn't a rare fluke but a common survival trick happening in contaminated sediments across many rivers.
Key Findings
Adding hydrogen gas to sediment microcosms stimulated arsenate (As(V)) reduction under low-oxygen conditions
DNA analysis identified Sulfuritalea, Dechloromonas, and a Moorellia-related bacterial lineage as the microbes responsible, each carrying both hydrogen-uptake enzymes and the arrA arsenate reductase gene
Roughly 75% of genomes containing the arrA gene also carry hydrogen-uptake [NiFe]-hydrogenases, and this genetic pairing showed up broadly across public river sediment datasets
chevron_right Technical Summary
Researchers discovered that certain sediment bacteria can 'breathe' hydrogen gas instead of oxygen while converting arsenic into a more dangerous, water-soluble form, and this microbial trick appears to be common in contaminated rivers worldwide.
Abstract Preview
Original paper
Hydrogen oxidation coupled to dissimilatory arsenate reduction: A potentially widespread pathway associated with arsenic mobility in anoxic sediments.
In aquatic environments, the arsenic (As) mobilization from anoxic sediments is an important process affecting water quality and associated health risks, as sediment-bound As can serve as a persist...
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