POTENTIAL DRIVERS OF A REGIONAL STREAMWATER NITRATE PULSE

Long-term streamwater chemistry monitoring provides insights into how forested catchments respond to environmental change. Around 2013, multiple headwater catchments across New Hampshire, New York, and Vermont showed a substantial increase in streamwater nitrate concentration. The similar timing of the increase raises questions about a potential regional driver. One possibility is regional climate variability impacting soil biogeochemical processes (e.g., nitrification) or novel hydrologic transport processes. The other possibility is soil biogeochemistry experienced an episode during the recovery from elevated acid deposition. This talk will present evidence of the regional streamwater nitrate increase, highlight our current hypotheses for the most likely drivers, and discuss the implications for catchment biogeochemsitry under recent environmental change.