Extreme flooding mobilized dissolved organic matter from coastal forested wetlands

Hamed Majidzadeh, Habibullah Uzun, Alexander Ruecker, David Miller, Jeffery Vernon, Hongyuan Zhang, Shaowu Bao, Martin T.K. Tsui, Tanju Karanfil, Alex T. Chow*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)

Abstract

Two intense rainfalls [Hurricane Joaquin (2015) and Hurricane Matthew (2016)], one year apart, provided a unique opportunity to examine changes in dissolved organic matter (DOM) dynamics in coastal blackwater rivers under extreme flooding conditions in the southeastern United States. Two sites along Waccamaw River (a coastal blackwater river) and the outflow of 18 sub-basins of Yadkin-Pee Dee Basin were sampled during and after the flooding events. The peaks of dissolved organic carbon (DOC) and nitrogen (DON) concentrations were observed 18 and 23 days after peak discharge in 2015 and 2016, respectively. Moreover, DOM aromaticity and abundance of humic substances significantly increased during the same period. Separation of discharge hydrograph into surface runoff and subsurface flow suggested that temporal changes were mainly due to contributions from subsurface flow flushing organic matter from wetlands and organic-rich riparian zones. The spatial analysis highlighted the key role of the forested wetlands as the only land use that significantly correlated with both DOM quantity (DOC and DON load) and DOM composition (i.e., aromaticity). The Yadkin-Pee Dee River basin alone exported more than 474 million kg DOC into the ocean during high-flow conditions from the 2016 event, indicating that such extreme short-term events mobilized enormous amounts of organic carbon and nitrogen to the ocean. Considering the predicted increase in frequency and intensity of extreme rainfall events in the eastern U.S., the results of this study can shed light on changes in DOM dynamics that may occur under such conditions in the near future.

Original languageEnglish
Pages (from-to)293-309
Number of pages17
JournalBiogeochemistry
Volume136
Issue number3
DOIs
Publication statusPublished - 1 Dec 2017
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2017, Springer International Publishing AG.

Keywords

  • Dissolved organic carbon
  • Hurricane
  • Joaquin
  • Matthew
  • Southeastern US

Fingerprint

Dive into the research topics of 'Extreme flooding mobilized dissolved organic matter from coastal forested wetlands'. Together they form a unique fingerprint.

Cite this