Atmospheric deposition is the major pathway for removal of organic carbon (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. Transfers of OC from the atmosphere to land occur as wet deposition (via precipitation) and as dry deposition (via surface settling of particles and gases). Despite the significance of DOC in ecosystem processes, studies regarding the abundance of OC in precipitation are relatively sparse, in part due to the fact that concentrations of organics in precipitation and their associated rates of atmospheric deposition are not routinely measured as a part of major deposition monitoring networks. We quantified the delivery of OC to the landscape via atmospheric deposition over space and time in order to assess atmospheric inputs of OC in the context of their quantitative relevance for watershed nutrient budgets. Our synthesis of global data on concentrations and deposition rates of OC showed substantial inputs of OC in both urban and rural settings. The rates of OC wet deposition measured from weekly samples collected through a National Atmospheric Deposition Program network of sites across Pennsylvania showed a pronounced seasonality. Sequential sampling of precipitation at a Critical Zone Observatory site in Pennsylvania revealed that the variability in OC quantity and quality within individual events is comparable to that between events. The relative importance of factors affecting DOC wet deposition varies between seasons and individual events and is linked to storm characteristics and tracks, antecedent dry periods, synoptic meteorological conditions, and oxidative atmospheric chemistry.
Iavorivska, L., and Boyer, E.W. (2016): Inputs of Organic Carbon to Watersheds via Atmospheric Deposition: Variation Across Spatial and Temperal Scales. 2016 Fall Meeting, American Geophysical Union, San Francisco, CA, 12-16 Dec..
This Paper/Book acknowledges NSF CZO grant support.