Water and Chemical Budgets for Terrestrial Basins at the Turkey Lakes Watershed

Twenty terrestrial basins ranging in area from 2.3 to 62.7 ha were monitored in the 1050-ha Turkey Lakes Watershed (TLW) to measure discharge and ion loss from the terrestrial ecosystem and to estimate terrestrial contributions to the main aquatic system. These basins span 400 m of elevation, beginning at 60 m above Lake Superior (183 m a.s.l.). Annual streamflow represented 28–63% of precipitation; 30–60% of the total occurred during springmelt. Water, H + , and NH 4 + output of the small basins increased with basin elevation; conductivity, alkalinity, Ca 2+ , and NO 3 − decreased. Losses of Mg 2+ , K + , Na + , SO 4 2− , and Cl − were not related to basin elevation. Input–output values indicate a net loss of Ca 2+ , Mg 2+ , K + , and Na + ; Cl − slowly accumulated, N was strongly retained, and SO 4 2− was generally in balance. Alkalinity values indicate that HCO 3 − was important in balancing cation losses in low-elevation basins but that SO 4 2− dominated in high-elevation basins. Output of H + was substantially lower than its input through precipitation at ail elevations; however, H + removal by the terrestrial system was greater in low-elevation than in high-elevation basins within the main watershed. Precipitation quantity and SO 4 2− and NO 3 − input were measured at the Atmospheric Environment Service APN station southeast of the TLW; other chemical parameters were measured on samples collected near the main outlet on the west side of the TLW.