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

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.