Atmospheric Transport\nof Semivolatile Organic Contaminants\nacross an Urban-Alpine Boundary

Current understanding of atmospheric transport of semivolatile\norganic contaminants (SVOCs) in alpine areas is limited due to complex\nmeteorology and topography. Salt Lake City, Utah borders protected\nwilderness areas in the Wasatch Mountains, exhibiting a useful model\nsystem in which an urban source of SVOCs, including polyaromatic hydrocarbons\n(PAHs) and polychlorinated biphenyls (PCBs), is located directly adjacent\nto an alpine sink. Our objective was to investigate the impacts of\ntopographical features on the transport and deposition of SVOCs across\nan urban-alpine boundary. To do so, we measured PAHs and PCBs in soils\nalong a transect starting at the urban-mountain interface and extending\ninto an alpine wilderness, crossing several prominent ridgelines.\nConcentrations of PAHs and PCBs in soils were heavily influenced by\nsoil organic carbon content, air temperature, and proximity to the\nurban boundary. However, the role of source proximity was only revealed\nafter normalizing concentrations in soil to organic carbon content\nand air temperature. Further, we present evidence of SVOC emission/deposition\ncycles driven by diurnal alpine winds that do not extend past topographical\nfeatures. Our results illustrate the roles of multiple competing processes\non SVOC transport in alpine systems and their importance at an urban-alpine\nboundary.