The chemical responses of acidic Woods Lake, NY to two different treatments with calcium carbonate

Abstract

A study was conducted to compare and contrast two approaches to neutralize an acidic lake by CaCO₃ addition (Woods Lake, Adirondack Mountains, New York, U.S.A.; 42°52′ N, 71°58′ W); direct water column treatment and treatment of both the water column and sediment. The latter treatment strategy was designed to release a slow, diffusive Ca²⁺. flux across the sediment/water interface and thereby delay the rate of reacidification. Both applications satisfactorily increased the acid neutralizing capacity (ANC) and Ca²⁺ of the lake, temporarily buffering the water column pH against acidic inputs from the watershed. The water column/sediment application involved a greater (50% more) dose in order to accomplish sediment treatment and resulted in a prolonged period of positive ANC in the water column. However, both treatments neutralized approximately the same quantity of runoff and equivalence of acidic inputs. Water column/sediment treatment may be an effective approach to help delay reacidification in shallow lakes of moderate hydraulic retention times. Unfortunately, many acidic Adirondack lakes have very short hydraulic retention times (<0.5 yr) and may not be neutralized for adequate durations by either water column or water column/sediment CaCO₃ treatments.