Georgia Coastal Ecosystems LTER Data Set Details

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GCE-LTER Data Set Summary

Accession:

ORG-GCED-2208

Research Theme:

Organic Matter/Decomposition (Directed Study)

Contributor:

Patricia M. Medeiros

Title:

DOM composition in Altamaha River and Sapelo Sound estuaries measured by FT-ICR mass spectrometry in 2017 (April, July, October) and 2018 (January and October)

Abstract:

Extreme events such as hurricanes and tropical storms often result in large fluxes of dissolved organic carbon (DOC) to estuaries. Precipitation associated with tropical storms may be increasing in the southeastern U.S., which can potentially impact dissolved organic matter (DOM) dynamics and cycling in coastal systems. Here, DOM composition at the Altamaha River and Estuary (Georgia, U.S.A.) was investigated over multiple years capturing seasonal variations in river discharge, high precipitation events, and the passage of two hurricanes which resulted in substantial storm surges. Optical measurements of DOM indicate that the terrigenous signature in the estuary is linearly related to freshwater content and is similar after extreme events with or without a storm surge and during peak river flow. Molecular level analysis revealed significant differences, however, with a large increase of highly aromatic compounds after extreme events exceeding what would be expected by freshwater content alone. Although extreme events are often followed by increased DOC biodegradation, the terrigenous material added during those events does not appear to be more labile than the remainder of the DOM pool that was captured by ultrahigh-resolution mass spectrometry analysis. This suggests that the added terrigenous organic matter may be exported to the coastal ocean, while a fraction of the organic matter that co-varied with the terrigenous DOM may contribute to the increased biomineralization in the estuary, with implications to carbon processing in coastal areas.

DOI:

10.6073/pasta/c0238aed6c397414f5925aff9f4a19ad

Key Words:

Altamaha River, biogeochemistry, carbon, carbon cycling, dissolved organic carbon, DOM, estuaries, hurricanes, hydrology, rivers, Sapelo Sound, storms

LTER Core Area:

Organic Matter

Research Themes:

Organic Matter/Decomposition, Chemistry

Study Period:

01-Apr-2017 to 31-Oct-2018

Study Sites:

GCE1 -- Eulonia, Georgia, USA
GCE7 -- Carrs Island, Georgia, USA

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Data References:

ORG-GCET-1904 (FT-ICR mass spectrometry from September 2015 to September 2016)

Publications:

Letourneau, M.L., Schaefer, S.C., Chen, H., McKenna, A.M., Alber, M. and Medeiros, P.M. 2021. Spatio-temporal changes in dissolved organic matter composition along the salinity gradient of a marsh-influenced estuarine complex. Limnology & Oceanography. 66:3040-3054. (DOI: 10.1002/lno.11857)

Medeiros, P.M. 2022. The effects of hurricanes and storms on the composition of dissolved organic matter in a southeastern U.S. estuary. Frontiers in Marine Science. 9:855720. (DOI: 10.3389/fmars.2022.855720)

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