Title

Assessing Dissolved Organic Matter Dynamics and Source Strengths in a Subtropical Estuary: Application of Stable Carbon Isotopes and Optical Properties

Authors

Chao Ya, Southeast Environmental Research Center and Department of Chemistry & Biochemistry, Florida International UniversityFollow
William T. Anderson, Southeast Environmental Research Center and Earth Sciences Department, Florida International UniversityFollow
Rudolf Jaffe´, Southeast Environmental Research Center, Department of Chemistry and Biochemistry, Florida International University,Follow

Abstract

The dynamics of dissolved organic matter (DOM) in subtropical coastal bays are complex. For example, variations in DOM characteristics and sources in Florida Bay are believed to be mainly driven by both hydrology and associated runoff of terrestrial DOM, and by primary productivity mostly from seagrass sources. However, confirmation and quantification of different DOM sources are still incomplete and needed for carbon budget assessments. Optical parameters based on excitation emission matrix fluorescence coupled with parallel factor analysis (EEM–PARAFAC) that had previously been tentatively assigned to both terrestrial and seasgrass sources. These correlated linearly with determined δ¹³C values, confirming an allochthonous, hydrologically-driven terrestrial source for the humic-like fluorescent components, while autochthonous DOM reflected by the protein-like fluorescence is mainly derived through primary productivity of seagrass communities. This study demonstrated the feasibility of combining optical signatures and stable isotopes in advancing the understanding of DOM dynamics in estuarine systems. Using stable carbon isotopic signatures of DOM, and applying a simple two end-member mixing model, the relative contributions of these two sources to the DOM pool in the bay were estimated. Results indicate that the highest proportion of DOM (ca. 72%) during the dry season was seagrass-derived, but clear variations were observed on both spatial and temporal scales. Limitations to the application of optical properties for the quantitative estimation of DOM sources in such coastal systems are discussed.

Comments

Copyright © 2014 Elsevier Ltd. All rights reserved.

DOI: http://dx.doi.org/10.1016/j.csr.2014.10.005

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DEB-1237517, #DBI-0620409, and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Ya, C., W.T. Anderson, R. Jaffe. 2014. Assessing dissolved organic matter dynamics and source strengths in a subtropical estuary: Application of stable carbon isotopes and optical properties. Continental Shelf Research 92: 98-107. DOI: 10.1016/j.csr.2014.10.005