Influence of Vegetational Structure on Capture of Salt and Nutrient Aerosols in a Maine Peatland

Abstract

Concentrations and fluxes of Cl‐ and Na+ in bulk precipitation and throughfall in an inland, acidic peatland (Alton Bog, Maine, USA) reveal the influence of canopy structure on the deposition rate of road‐salt and nutrient‐bearing aerosols. Alton Bog borders a four‐lane highway that is salted in winter. In open areas of the peatland steep gradients occurred in both Cl‐ and Na+ influxes in bulk precipitation and in surface‐water concentrations within ≈ 200 m of the highway. In winter, wooded sites had consistently higher atmospheric influxes of Cl‐ (up to 4X) than did treeless sites at the same distance from the highway. These results were consistent with expectations based on studies of dry deposition in nonpeatland areas. The increased influx of Cl‐ at wooded sites implies a significantly higher total influx of nutrients in peatlands where trees occur (especially unevenly spaced trees of mixed heights) than in peatlands with no trees. The effect is likely to be especially important in peatlands that receive all or most incoming nutrients from the atmosphere