Kasta ljus på den mörka reduktion som mobiliserar kvicksilver i torv

Anthropogenic Hg emissions to the atmosphere have increased this potent neurotoxin in ecosystems. Efforts to control Hg pollution has halved atmospheric Hg over Sweden since 1980.

The first annual Hg mass-balance for a boreal peatland that measured peat-atmosphere exchange revealed so much Hg evasion that the mire will have recovered in decades, rather than in centuries as previously believed. Producing this mass balance was a methodological challenge, but explaining it presents new scientific challenges.

The time Hg spends in the uppermost decimeters of peat between atmospheric deposition on the surface and long-term immobilization deeper in the peat is a period when remobilization is possible, provided the pollution legacy Hg can be reduced to dissolved gaseous Hg (DGM) in the absence of light. Dark Hg reduction can do this.

Despite the potentially critical role of such processes though, they remain poorly characterized.

We will test the hypothesis that dark Hg reduction controls the rate at which legacy Hg evades from peatlands and explore how both biotic and abiotic processes associated with specific microbial metabolic pathways interact to control dark Hg reduction. Hg evasion and porewater DGM measurements will test that this product of dark Hg reduction is driving the evasion.

Reduction assays on microcosms will investigate the roles of specific processes associated with different microbial metabolic pathways in controlling the dark Hg reduction creating DGM.