Potential relative future effects of sulfur and nitrogen deposition on lake chemistry in the Adirondack Mountains, United States

Leaching of atmospherically deposited nitrogen from forested watersheds can acidify lakes and streams. Using a modified version of the Model of Acidif ication of Groundwater in Catchments, we made computer simulations of such effects for 36 lake catchments in the Adirondack Mountains of New York Stat e. Our simulations bound the potential changes in regional-scale surface wa ter acidification that might occur there over the next 50 years across broa d scenarios of both nitrogen and sulfur deposition as well as ranges of tim es to watershed nitrogen saturation. Model projections indicated that nitro gen deposition may play a more important role in future acidification than has been previously considered and may rival or exceed potential effects of sulfur deposition, depending on how rapidly watersheds might become satura ted with atmospherically deposited nitrogen.