Methane biogeochemical turnover constrains arsenic transformation in groundwater systems: Organic molecular signatures and microbial functional networks.
Xie X, Li E, Jiang H, Pi K, Yan L
Soil Health
Arsenic from contaminated groundwater moves into soil and gets absorbed by crops like rice and leafy vegetables — understanding what triggers its release helps explain why produce from certain regions may carry higher arsenic loads.
Deep underground, tiny microbes that make and consume methane gas also — as a side effect — free up arsenic locked in sediment, pushing it into groundwater. The study found that the type of organic material in the water acts like a dial, controlling how fast and how much arsenic gets released. This means the chemistry of underground water shapes not just what we drink, but what ends up in the soil where our food grows.
Key Findings
Methane oxidation tripled arsenic(III) release rates, from 1.04 to 3.30 μg per kg per day, making methane-consuming microbes a key driver of arsenic contamination.
Methane-producing microbes ramped up methane output to 7.23 mg per kg per day, while methane-consuming microbes increased oxidation rates more than twofold (94.99 to 190.76 mg per kg per day).
Humified (well-decomposed) organic matter broke the usual iron-arsenic geochemical link, suggesting that soil organic matter quality fundamentally changes arsenic behavior in groundwater.
chevron_right Technical Summary
Researchers discovered that methane-producing and methane-consuming microbes in groundwater dramatically accelerate the release of toxic arsenic, with methane oxidation tripling arsenic mobilization rates. The type of organic matter present controls which microbial communities thrive and ultimately determines how much arsenic ends up in drinking water.
Abstract Preview
Arsenic (As) contamination of groundwater is primarily driven by microbially mediated redox processes and the dynamic evolution of dissolved organic matter (DOM). The influence of cycled methanogen...
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