The Feasibility and Effectiveness of Summer Season or Episodic SO₂ Emission Controls to Reduce Acidic Deposition in Eastern North America

Abstract

While it is generally agreed that an acid deposition problem exists in eastern North America where depositions have exceeded the natural buffering capacity of the aquatic ecosystem, the most fair and economical solution to controlling precursor emissions is very controversial and subject to scientific uncertainty. The search for a fair and economical solution has evolved in recent years from considering a large uniform percentage rollback in SO₂ emissions from all sources in eastern North America to protect a number of small geographically dispersed sensitive areas, to considering a much smaller, non-uniform, reduction from primarily utility sources in a subregion, like just 10–12 states, to protect primarily the Adirondack sensitive area in upper New York State, The term “targeted approach” has been applied to the latter since the control strategy is targeting a limited geographical source region, receptor area, and source category. Some proponents of the targeted approach have suggested that it could be carried even a step further by targeting the SO₂ emission control to primarily the season or episodes which contribute most to the annual total wet sulfate depositions1,2. It is generally known that wet sulfate depositions are greatest in the summer season when the precipitation amounts are generally greatest and SO₂ to (math) photo- and aqueous-phase chemistries are enhanced by abundant solar radiation, moisture, and pollutants like oxidants.