Source Attribution of Atmospheric Mercury Deposition to Tampa using Positive Matrix Factorization

Mercury is a pervasive global pollutant with debilitating health outcomes, and an exposure pathway that transcends social and economic boundaries. Wet deposition processes are central to the entry of mercury into aquatic ecosystems, where it bioaccumulates in piscivorous species. Fish consumption is the leading route to mercury exposure for vulnerable populations such as women of child-bearing age, subsistence fisher folk, and those consuming high seafood diets. However, substantial uncertainties exist in attributing deposition levels to local versus long-range emission sources. Here, we investigate the deposition and sources contributing to mercury loading in the Tampa Bay region. Positive matrix factorization (PMF) receptor analysis was applied to one year of special precipitation event data from the Bay Regional Atmospheric Chemistry Experiment, for a site in Tampa, to apportion source influence types. An 11-factor model was found to account for maximum uncertainties in the 25-species dataset. Eleven unique source profiles were identified as contributing to the species masses observed in the dataset. Four sources were found to account for greater than 90% of mercury species mass observed in the dataset. Municipal and medical waste incineration and coal fuel combustion sources accounted for mercury mass deposition. PMF receptor analysis indicates significant influences from medical and municipal waste incinerators and utility coal boilers, with a much smaller contribution from a likely traffic-related source. Taken in the context of the local emissions inventory data, these results suggest substantial contributions to area mercury wet deposition from sources in Florida and local to the Tampa Bay region.