Limitations on using CDOM as a proxy for DOC in temperate lakes

WATER RESEARCH

卷:144

Article

Griffin, Claire G.¹  Finlay, Jacques C.¹  Brezonik, Patrick L.²  Olmanson, Leif³  Hozaiski, Raymond M.² 

[1] Univ Minnesota, Dept Ecol Evolut & Behav, St Paul, MN 55108 USA

[2] Univ Minnesota, Dept Civil Environm & Geoengn, Minneapolis, MN USA

[3] Univ Minnesota, Dept Forest Resources, Remote Sensing & Geospatial Anal Lab, St Paul, MN USA

关键词: Colored dissolved organic matter;    Dissolved organic carbon;    Lakes;    Aquatic carbon cycle;   

DOI  :  10.1016/j.watres.2018.08.007

来源: Elsevier

【 摘 要 】

Colored dissolved organic matter (CDOM) has been widely studied as part of efforts to improve understanding of the aquatic carbon cycle, by laboratory, in situ, and remote sensing methods. We studied ecoregion-scale differences in CDOM and dissolved organic carbon (DOC) to understand variability in organic matter composition and the use of CDOM as a proxy for DOC. Data from 299 lakes across the U.S. Upper Midwest showed that CDOM, measured as absorptivity at 440 nm (n44o), correlated strongly with DOC (R-2 = 0.81, n = 412). Colored lakes in the Northern Lakes and Forests (NLF) ecoregion drove this relationship. Lakes in the North Central Hardwood Forests (NCHF) had low color (most had a(440) <3 m(-1)) and weaker CDOM-DOC relationships (R-2 = 0.47). Spectral slopes and specific ultraviolet absorbance (SUVA), indicated relatively low aromaticity and non-terrestrial DOM sources in low color lakes. Multiple regression analyses that included total dissolved nitrogen (TDN) and CDOM, but not chlorophyll a, improved DOC estimates in low color lakes, suggesting a dominant contribution of non-planktonic sources of low color DOM in these lakes. Our results show that CDOM is a reliable, regional proxy for DOC in lakes where forests and wetlands dominate the landscape and the DOM is primarily terrestrial in origin. Mapping of lake DOC at broad spatial scales by satellite-derived CDOM has lower accuracy in low color lakes. (C) 2018 Elsevier Ltd. All rights reserved.

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