title: Climate change and emissions impacts on atmospheric PAH transport to the Arctic.
abstract: We investigate effects of 2000-2050 emissions and climate changes on the atmospheric transport of three polycyclic aromatic hydrocarbons (PAHs): phenanthrene (PHE), pyrene (PYR), and benzo[a]pyrene (BaP). We use the GEOS-Chem model coupled to meteorology from a general circulation model and focus on impacts to northern hemisphere midlatitudes and the Arctic. We project declines in anthropogenic emissions (up to 20%) and concentrations (up to 37%), with particle-bound PAHs declining more, and greater declines in midlatitudes versus the Arctic. Climate change causes relatively minor increases in midlatitude concentrations for the more volatile PHE and PYR (up to 4%) and decreases (3%) for particle-bound BaP. In the Arctic, all PAHs decline slightly under future climate (up to 2%). Overall, we observe a small 2050 "climate penalty" for volatile PAHs and "climate benefit" for particle-bound PAHs. The degree of penalty or benefit depends on competition between deposition and surface-to-air fluxes of previously deposited PAHs. Particles and temperature have greater impacts on future transport than oxidants, with particle changes alone accounting for 15% of BaP decline under 2050 emissions. Higher temperatures drive increasing surface-to-air fluxes that cause PHE and PYR climate penalties. Simulations suggest ratios of more-to-less volatile species can be used to diagnose signals of climate versus emissions and that these signals are best observed in the Arctic.
authors.affiliation: Center for Global Change Science, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
authors.forename: Carey L
authors.initials: CL
authors.lastname: Friedman
authors.forename: Yanxu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Noelle E
authors.initials: NE
authors.lastname: Selin
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D001110:Arctic Regions; D001564:Benzo(a)pyrene / Q000032:analysis*; D057231:Climate Change; D004784:Environmental Monitoring; D019652:Extraction and Processing Industry; D008962:Models, Theoretical; D010578:Petroleum; D010616:Phenanthrenes / Q000032:analysis*; D011721:Pyrenes / Q000032:analysis*; D012767:Ships
chemical_list: D000393:Air Pollutants; D010578:Petroleum; D010616:Phenanthrenes; D011721:Pyrenes; D001564:Benzo(a)pyrene; C031181:phenanthrene; C030984:pyrene