Extensive CO₂ emissions from shallow coastal waters during passage of Hurricane Irene (August 2011) over the Mid‐Atlantic Coast of the U.S.A

Abstract

Shallow coastal waters serve an important role as long-term carbon (C) sinks because they capture terrestrial C and retain internally produced C in wetlands and sediments. We show that tropical cyclones (TCs) can lead to rapid CO 2 efflux from estuaries, driven by physical and biogeochemical perturbation of these coastal C reservoirs, and that the magnitude of TC-driven CO 2 emissions may offset C that accumulates over much longer timescales. In August 2011, Hurricane Irene passed over North Carolina's Neuse River Estuary-Pamlico Sound (NRE-PS), which is part of the second largest estuarine system in the U.S., the Albemarle-Pamlico Sound. Irene rapidly changed the NRE-PS system from a small CO 2 sink to a large CO 2 source. Irene-induced CO 2 efflux from the NRE alone was at least four times the annual riverine C input and seven times the annual atmospheric CO 2 uptake. The magnitude and duration of ecosystem disturbance from TCs vary with storm intensity and frequency but likely are qualitatively similar across many terrestrial and coastal systems. Consequently, altered TC activity under future climate scenarios may shift the balance between C accumulation in, and release from, coastal C reservoirs.

Lingering Carbon Cycle Effects of Hurricane Matthew in North Carolina's Coastal Waters

“…Nutrient‐driven primary production in the NRE‐PS is dramatically enhanced by hurricanes, which may partially explain the observed POC and δ 13 C values (Paerl et al, , ). These C:N and δ 13 C values could also be explained in part by the resuspension of estuarine sediment, as has been suggested for previous EWEs (Crosswell et al, ).…”

“…That flux decreased to about 8.27 × 10 7 g C/day about 20 days after the storm. Daily riverine DOC fluxes to the NRE‐PS increased by nearly a factor of 20 after Hurricane Matthew, much larger than the fivefold increase after Hurricane Irene in 2011 (Crosswell et al, ). Riverine POC flux was 1.77 × 10 8 g C/day 2 weeks after Hurricane Matthew, decreasing to 2.62 × 10 6 g C/day after ~3 weeks.…”

Carbon Budget of Tidal Wetlands, Estuaries, and Shelf Waters of Eastern North America

“…A total of 16 literature estimates of U E were compiled (Cai & Wang, 1998;Crosswell et al, 2014Crosswell et al, , 2012Hunt et al, 2014Hunt et al, , 2011Jiang et al, 2008;Joesoef et al, 2015;Raymond & Hopkinson, 2003;Raymond et al, 2000;Wang & Cai, 2004; Table S2 in the supporting information), and means and standard errors were computed for each subregion.…”

Bubble Clouds in Coastal Waters and Their Role in Air-Water Gas Exchange of CO2

“…Figure 4 illustrates how bubbles can be mixed throughout the entire water column of shallow, long-fetch estuaries during storm events. In frequently-stratified systems like CHB, the mixture of bubbles with high-CO2 bottom water and porewater could release a substantial quantity of CO2 to the atmosphere [80]. Hence, episodic perturbations by storms can have a large impact on estuarine gas fluxes relative to the short time scales on which they occur.…”

“…Crosswell et al [80] estimated that in a shallow, seasonally-stratified estuary, the CO2 efflux due to a single tropical cyclone (Hurricane Irene, 2011) could equal the net air-water CO2 transport over several cyclone-free years. Storm-generated bubble plumes had a smaller impact in deep or fetch-limited systems, e.g., LIS and CHB99 (Figure 4).…”