Strategies for emission controls to mitigate snowmelt acidification

Abstract

Elevated atmospheric deposition of strong acids contributes to short‐term/seasonal acidification of surface waters draining sensitive northern forests of North America and Europe during high flow. Reducing atmospheric deposition of NO3− and/or SO42−, therefore, could improve the health of aquatic ecosystems by mitigating episodic acidification. We used an integrated biogeochemical model (PnET‐BGC) to simulate the effects of acidic deposition on seasonal variations in surface water chemistry, and to evaluate emission control scenarios to decrease acidification during snowmelt. Model calculations suggest that historical long‐term inputs of acidic deposition have altered the seasonal patterns in surface water chemistry. Although short‐term increases in NO3− coincide with snowmelt acidification, model simulations indicate reductions in SO42− deposition result in larger benefits than an equivalent reduction in NO3− deposition. Year‐around reductions in NO3− deposition are also more beneficial to the acid‐base status of stream water than summer‐only reductions.