Georgia Coastal Ecosystems LTER Data Set Details

Jump to Files

GCE-LTER Data Set Summary

Accession:

ORG-GCET-1904

Research Theme:

Organic Matter/Decomposition (Graduate Thesis Study)

Contributors:

Patricia M. Medeiros, Maria Letourneau

Title:

DOM composition changes in Altamaha River and Sapelo Sound estuaries measured by FT-ICR mass spectrometry from September 2015 to September 2016

Abstract:

Dissolved organic matter (DOM) is a large and complex mixture of compounds with source inputs that differ with location, season and environmental conditions. Here, we investigated drivers of DOM composition changes in a marsh-dominated estuary off the southeastern U.S. Monthly water samples were collected at a riverine and estuarine site from September 2015 to September 2016, and bulk, optical, and molecular analyses were conducted on samples before and after dark incubations. Results showed that river discharge was the primary driver changing the DOM composition at the mouth of the Altamaha River. For discharge higher than ~ 150 m3 s-1, DOC concentrations and the terrigenous character of the DOM increased approximately linearly with river flow. For low discharge conditions, a clear signature of salt marsh-derived compounds was observed in the river. At the head of Sapelo Sound, changes in DOM composition were primarily driven by river discharge and possibly by summer algae blooms. Microbial consumption of DOC was larger during periods of high discharge at both sites, potentially due to the higher mobilization and influx of fresh material to the system. The Georgia coast was hit by Hurricane Matthew in October 2016, which resulted in a large input of carbon to the estuary. The DOC concentration was ~ 2 times higher and DOM composition was more aromatic with a stronger terrigenous signature compared to the seasonal maximum observed earlier in the year during peak river discharge conditions. This suggests that extreme events notably impact DOM quantity and quality in estuarine regions.

DOI:

10.6073/pasta/6a1db75bfc051e704cf35497dd9551e7

Key Words:

Altamaha River, biogeochemistry, carbon, carbon cycling, dissolved organic carbon, DOM, estuaries, hydrology, rivers, Sapelo Sound, spectroscopy, terrigenous

LTER Core Area:

Organic Matter

Research Themes:

Organic Matter/Decomposition, Chemistry

Study Period:

15-Sep-2015 to 11-Sep-2016

Study Sites:

GCE1 -- Eulonia, Georgia, USA
GCE-AL -- Altamaha River, Georgia, USA

» Download Geographic Coverage: Google Earth

Data References:

ORG-GCED-2208 (FT-ICR mass spectrometry in 2017 (April, July, October) and 2018 (January and October))

Publications:

Letourneau, M.L. and Medeiros, P.M. 2019. Dissolved organic matter composition in a marsh-dominated estuary: Response to seasonal forcing and to the passage of a hurricane. Journal of Geophysical Research: Biogeosciences. 124:1545-1559. (DOI: 10.1029/2018JG004982)

Downloads:

Data Table: ORG-GCET-1904 ( Physical and chemical variables at sampling sites collected over one year in the Altamaha River and Sapelo Sound, 27 records)