Modeling the global atmospheric transport and deposition of mercury to the Great Lakes

Abstract

Mercury contamination in the Great Lakes continues to have important public health and wildlife ecotoxicology impacts, and atmospheric deposition is a significant ongoing loading pathway. The objective of this study was to estimate the amount and source-attribution for atmospheric mercury deposition to each lake, information needed to prioritize amelioration efforts. A new global, Eulerian version of the HYSPLIT-Hg model was used to simulate the 2005 global atmospheric transport and deposition of mercury to the Great Lakes. In addition to the base case, 10 alternative model configurations were used to examine sensitivity to uncertainties in atmospheric mercury chemistry and surface exchange. A novel atmospheric lifetime analysis was used to characterize fate and transport processes within the model. Model-estimated wet deposition and atmospheric concentrations of gaseous elemental mercury (Hg(0)) were generally within ∼10% of measurements in the Great Lakes region. The model overestimated non-Hg(0) concentrations by a factor of 2-3, similar to other modeling studies. Potential reasons for this disagreement include model inaccuracies, differences in atmospheric Hg fractions being compared, and the measurements being biased low. Lake Erie, downwind of significant local/regional emissions sources, was estimated by the model to be the most impacted by direct anthropogenic emissions (58% of the base case total deposition), while Lake Superior, with the fewest upwind local/regional sources, was the least impacted (27%). The U.S. was the largest national contributor, followed by China, contributing 25% and 6%, respectively, on average, for the Great Lakes. The contribution of U.S. direct anthropogenic emissions to total mercury deposition varied between 46% for the base case (with a range of 24-51% over all model configurations) for Lake Erie and 11% (range 6-13%) for Lake Superior. These results illustrate the importance of atmospheric chemistry, as well as emissions strength, speciation, and proximity, to the amount and source-attribution of mercury deposition.

Multi-model study of mercury dispersion in the atmosphere: vertical and interhemispheric distribution of mercury species

“…Consequently, mercury oxidation processes have been the focus of the international mercury community in recent years Cohen et al, 2016;Amos et al, 2015;Dastoor et al, 2015;Song et al, 2015;Bieser et al, 2014a;De Simone et al, 2014;Qureshi et al, 2011;Travnikov et al, 2010).…”

Ensemble PM2.5 Forecasting During the 2018 Camp Fire Event Using the HYSPLIT Transport and Dispersion Model

“…HYSPLIT has also been used in a variety of simulations describing the atmospheric transport, dispersion, and deposition of pollutants and hazardous materials. Examples include tracking and forecasting the release of radioactive material (Rolph et al, 2014), windblown dust (Gaiero et al, 2013), pollutants from various stationary and mobile emission sources (Chen et al, 2013), allergens (Efstathiou et al, 2011), volcanic ash (Crawford et al, 2016;Vernon et al, 2018), dioxin (Cohen et al, 2002;Schaum et al, 2010), and mercury (Cohen et al, 2004(Cohen et al, , 2016. HYSPLIT has been used since 2007 in an operational smoke forecast system at NOAA in which fire locations and areas are estimated from satellite data, BB data (e.g., PM 2.5 emissions, and heat release) are estimated using the bottom-up, fuel-based Blue Sky modeling system developed by the U.S. Forest Service, and NOAA weather forecast model output is used to drive the HYSPLIT model (Rolph et al, 2009;Stein et al, 2009).…”

Long-Term Observations of Atmospheric Speciated Mercury at a Coastal Site in the Northern Gulf of Mexico during 2007–2018

“…While Hg ubiquitously exists in the natural environment, anthropogenic activities have moved previously sequestered materials (e.g., Hg in coal and metallurgical ores) into the ecosphere and increased its bioavailability [2]. Global emissions of Hg to the atmosphere are estimated to be approximately one-third from direct anthropogenic sources, approximately one-third from re-emission of previously deposited anthropogenic emissions, and about one-third from natural sources, but there are significant uncertainties in the overall amounts and proportions, as well as the spatial, temporal, and chemical distribution of emissions [3][4][5]. The concentrations of Hg in the air are usually low and they are generally not an air quality concern.…”