Abstract
Mercury (Hg) is a naturally occurring element that bonds with organic matter and, when converted to methylmercury, is a potent neurotoxicant. Here we estimate potential future releases of Hg from thawing permafrost for low and high greenhouse gas emissions scenarios using a mechanistic model. By 2200, the high emissions scenario shows annual permafrost Hg emissions to the atmosphere comparable to current global anthropogenic emissions. By 2100, simulated Hg concentrations in the Yukon River increase by 14% for the low emissions scenario, but double for the high emissions scenario. Fish Hg concentrations do not exceed United States Environmental Protection Agency guidelines for the low emissions scenario by 2300, but for the high emissions scenario, fish in the Yukon River exceed EPA guidelines by 2050. Our results indicate minimal impacts to Hg concentrations in water and fish for the low emissions scenario and high impacts for the high emissions scenario.
Highlights
We divide the carbon and Hg into 13 pools representing different vegetation and soil components, such as leaves or humus[17]
We assume a Dissolved Organic Carbon (DOC) leaching fraction of total respiration of 1.5 × 10−3 g C g C−1 based on laboratory measurements and a Particulate Organic Carbon (POC) to DOC ratio of 9:1 to get a total aqueous HgII export fraction of 1.5%16,20,21 or 1.5 × 10−2 g HgII g Hg−1
The remaining 82.5% of released Hg recycles back into the organic matter
Summary
We divide the carbon and Hg into 13 pools representing different vegetation and soil components, such as leaves or humus[17]. We assume total atmospheric Hg deposition consists of 71% Hg0 and 29% HgII based on observations[9]. SiBCASA has two uptake pathways, bonding to soil organic matter and root absorption.
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