Abstract
The Laurentian Great Lakes contain ~ 21% of the Earth's surface freshwater and are experiencing dramatic decadal-scale changes to their water quality, biogeochemistry and ecosystem functions.We report here the first data set of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (DOM), including UV–visible absorbance and derived optical properties and fluorescence excitation–emission matrices (EEMs), for open-lakesurface waters from each of the Great Lakes. Concentrations of DOC ranged from 86 to 240 μmol/L and the absorption coefficient at 254 nm (a254) varied from 2.67 to 10.47 m− 1 in Great Lakes waters.UV–visible and fluorescence characterization indicated that the DOM in open-lake waters in all the Great Lakes was primarily autochthonous. Both DOC and a254 increased from Lake Superior to Lakes Erie and Ontario where aromaticity, molecular weight and humification degree of DOM were also higher.These variations are consistent with both the water transport pathway and the trend of increasing human population and relative watershed drainage area along the Great Lakes. Parallel factor analysis on fluorescence-EEM data revealed three terrestrial humic-likeDOM components (C1, C2 and C4) and one protein-likeDOM component (C3). Open Lake Huron had the highest protein-like/humic-like DOM ratio (C3/C1), while sites in Lakes Erie and Ontario had lower C3/C1 ratios, indicating a greater proportional influence of terrestrial DOM. Changes in DOM composition along the water transport pathway in the Great Lakes indicate varying impacts from terrestrial inputs and human activities in the different lake systems.
Original language | English (US) |
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Pages (from-to) | 789-801 |
Number of pages | 13 |
Journal | Journal of Great Lakes Research |
Volume | 42 |
Issue number | 4 |
DOIs | |
State | Published - Aug 1 2016 |
Bibliographical note
Funding Information:We are grateful to Asta Mail, the Pangaea Cruise Team and crewmembers of Sea Dragon for their assistance during field sampling. Thanks also to Hongyu Li, Prosper Zigah, and the captain and crew ofthe R/V Blue Heron for assistance in collection and analyses of Lake Superior samples, and Stephen DeVilbiss and three anonymous reviewers for their constructive comments which improved the manuscript. This study was supported in part by grants from NOAA Sea Grant (project R/HCE-16), the University of Wisconsin-Milwaukee (RGI-101X318), the Minnesota Environment and Natural Resources Trust Fund, and the National Science Foundation (OCE #0825600, OCE#0850957, and OCE #1233192).
Funding Information:
We are grateful to Asta Mail, the Pangaea Cruise Team and crewmembers of Sea Dragon for their assistance during field sampling. Thanks also to Hongyu Li, Prosper Zigah, and the captain and crew of the R/V Blue Heron for assistance in collection and analyses of Lake Superior samples, and Stephen DeVilbiss and three anonymous reviewers for their constructive comments which improved the manuscript. This study was supported in part by grants from NOAA Sea Grant (project R/HCE-16 ), the University of Wisconsin-Milwaukee ( RGI-101X318 ), the Minnesota Environment and Natural Resources Trust Fund , and the National Science Foundation (OCE # 0825600 , OCE# 0850957 , and OCE # 1233192 ).
Publisher Copyright:
© 2016 International Association for Great Lakes Research.
Keywords
- CDOM
- Dissolved organic matter
- Fluorescence EEMs
- PARAFAC analysis
- The Laurentian Great Lakes