Extreme storms and changes in particulate and dissolved organic carbon in runoff: Entering uncharted waters?

Abstract

We determined the runoff exports of particulate (POC) and dissolved organic carbon (DOC) from a 12 ha forested catchment which received more than 14 storm events in a 16-month period and three extreme events associated with hurricanes. While POC and DOC exports for the small events were comparable, POC exports for the hurricane-associated events were six to eight times the DOC values. Hurricane Irene alone contributed to 56% (21.2 kg C ha-1) and 19% (3.3 kg C ha-1) of the 2011 exports of POC and DOC, respectively. A precipitation threshold beyond which POC fluxes rapidly outpaced the DOC values was also identified. Our study suggests that large, high-intensity storm events that are predicted to increase under future climate-change scenarios will dramatically alter the runoff C regime by enhancing the POC inputs to aquatic ecosystems. Such shift in C forms could have important consequences for aquatic biota, atmospheric C cycling, and ecosystem and human health. Key Points POC mass exports during extreme storm events are much greater than DOC POC exports increase dramatically beyond a specific precipitation threshold Shift in C forms will impact water quality, C cycling and ecosystem health ©2013. American Geophysical Union. All Rights Reserved.