Regional scale photochemical model evaluation of mercury deposition in Mississippi

Deposition of atmospheric mercury plays a significant role in the formation of methyl mercury. The methyl mercury is a highly toxic compound that is associated with neuro-development defects in children, immune system suppression, memory loss, and an increase risk of cardiovascular disease. To to reduce methyl mercury, a reduction of atmospheric mercury is necessary. However, the atmospheric mercury cycle still pose a challenge to the society in that many important processes are poorly understood. These uncertainties are related to the scientific understanding of atmospheric mercury: characterizing global mercury emissions, chemical mechanisms - oxidation and reduction pathways between elemental and reactive mercury species, estimating deposition rates, and better understanding the gas-particle partitioning process. This research work will examine possible model uncertainties, specifically relating to the oxidation of elemental mercury, as well as investigating possible relationships between meteorological variables and the aqueous and gas-phase mercury species by Quantitatively analyzing three atmospheric mercury species – gaseous elemental mercury, reactive gaseous mercury and particulate mercury. This study will employs the Community Multiscale Air Quality Model with mercury chemistry (CMAQ-Hg), to examine how local emissions, meteorology, atmospheric chemistry, and deposition influence mercury concentration, transport and deposition. We will also examine the relationship between temperature (and wind) and ambient mercury. The the yearly observational data, including gaseous elemental mercury, gaseous oxidized mercury and particulate bound mercury, were obtained from the measurements on the University of Mississippi campus located in Oxford, Mississippi from 2011 to 2012 and to assess the air quality model performance.