Wet atmospheric deposition of organic carbon across Pennsylvania: rates and relation to inorganic elements of precipitation chemistry.

Lidiia Iavorivska1, Elizabeth Boyer2 and Jeffrey Grimm3

Transfers of organic carbon (OC) from the atmosphere to land occur as wet deposition (via precipitation) and as dry deposition (via surface settling of particles and gases). Wet deposition is the major pathway for removal of OC from the atmosphere, affecting both atmospheric and landscape processes. OC deposited with precipitation to the landscape affects organic acidity, nutrient balances, and metal complexation. Since OC is highly chemically reactive and bioavailable it influences productivity in aquatic ecosystems. Compared to a large body of research on atmospheric deposition of acidic compounds and persistent organic pollutants, studies regarding the abundance of OC in precipitation are relatively sparse.  One reason is that concentrations of OC in precipitation and their rates of atmospheric deposition are not routinely measured as a part of major deposition monitoring networks. Our synthesis of global data on concentrations and deposition rates of OC showed substantial inputs of OC in both urban and rural settings. Using aliquots from weekly samples collected through a National Atmospheric Deposition Program network of sites in Pennsylvania we quantified the inputs of OC to the landscape via atmospheric deposition across the state in order to assess their quantitative relevance for watershed nutrient budgets. The rates of OC wet deposition showed a pronounced seasonality and spatial distribution. Further, significant links between OC and inorganic constituents in precipitation, especially sulfate and inorganic nitrogen forms, suggest that they have similar sources and OC may affect their atmospheric transport and the ecological fate.


1Pennsylvania State University, lui100@psu.edu
2Pennsylvania State University, ewb100@psu.edu
3Pennsylvania State University, jg4@psu.edu