Resolving Atmospheric Mercury Loading and Source Trends from Isotopic Records of Remote North American Lake Sediments

• DOI: 10.1021/acs.est.0c00579
• Publication Date: 2020-06-27T14:03:10Z
• Authors: Ryan F. Lepak; Sarah E. Janssen; Daniel R. Engstrom; David P. Krabbenhoft; Michael T. Tate; Runsheng Yin; William F. Fitzge...; Sonia A. Nagorski; James P. Hurley
• Keywords: Mercury; Biogeochemical Cycle

The strongest evidence for anthropogenic alterations to the global mercury (Hg) cycle comes from historical records of deposition preserved in lake sediments. Hg isotopes have added a new dimension these sedimentary archives, promising additional insights into source apportionment and biogeochemical processing. Presently, most interpretations changes are constrained small number locally contaminated ecosystems. Here, we describe natural isotope suite dated sediment cores collected various remote lakes North America. In nearly all cases, rise industrial-use is accompanied by an increase δ202Hg Δ199Hg values. These trends can be attributed large-scale industrial emission atmosphere consistent with positive values measured modern-day precipitation modeled increases inventories. Despite similar temporal among cores, baseline isotopic vary considerably different study regions, likely attributable differences fractionation produced situ as well differing amounts atmospherically delivered Hg. Differences watershed size provide empirical framework evaluating signatures cycling.