Student Research Projects

Mercury Deposition to Deciduous versus Evergreen Tree Leaves

Student Rebecca Hyman, '16
Faculty Mentor(s)
Department Earth and Environmental Sciences
Course EES 270: Environmental Chemistry

Abstract

Mercury is a toxic heavy metal that is released into the atmosphere. Although found naturally, its largest source is from the burning of coal (Pacyana et al., 2011). When this mercury deposits to a watershed, it can become converted to the toxic methylmercury and bioaccumulate in organisms. One of these deposition mechanisms is the dry deposition of mercury gases and particles to tree leaves, which can then wash off the leaves as throughfall during precipitation. Throughfall of tree canopies have been found to have a higher mercury concentration that that of precipitation due to this deposition (Choi et al., 2007). Our study was conducted to find out whether there is a difference in mercury dry deposition on evergreen versus deciduous tree leaves in the coastal environment of Virginia. Our group sampled leaves from Red Oak and American Holly trees at First Landing State Park, agitated them in a container of D.I water to remove surface deposition, and then analyzed the rinse water for mercury. Mercury deposition levels were similar between the evergreen and deciduous leaves for our sampling date. We found that the two samples taken from the middle of the trees were lower in mercury than the samples taken from the outskirts. For future tests, we recommend sampling at a location closer to shore with higher atmospheric mercury levels and sampling in multiple seasons.