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Title: Using CDOM optical properties for estimating DOC concentrations and pCO 2 in the Lower Amazon River

Abstract

Colored dissolved organic matter (CDOM) is largely responsible for the optical properties of freshwaters and coastal areas and can be used as a proxy to assess the non-optical carbon content as the dissolved organic carbon (DOC) and the partial pressure of carbon dioxide (pCO 2). Nevertheless, riverine studies that explores the former relationship are more challenging due to the spectral mixture caused by the high content of inorganic materials in the suspended sediment. Here we evaluate the spatial-temporal variability of CDOM, DOC and pCO 2, as well as the potential of CDOM absorption coefficient (aCDOM(412)) for estimating DOC concentration and pCO 2 along the lower Amazon River. Our results revealed differences in the dissolved organic matter (DOM) quality between clear water (CW) tributaries and the Amazon River mainstem. A linear relationship between DOC and CDOM was observed when tributaries and mainstem are evaluated separately (Amazon waters: N=42, R2=0.74; CW: N= 13, R2 = 0.57). However, this linear relationship was not observed during periods of higher rainfall and river discharge, requiring a model specific to these time periods to be developed (N = 25, R2 = 0.58). A strong linear positive relation was found between aCDOM(412) and pCO 2( N=69, R2=0.65)more » along the lower river. pCO 2 was less affected by the optical difference between tributaries and mainstem water or by the presence of higher hygrometric conditions when compared to CDOM to DOC relationships. Including the river water temperature in the model improves our ability to estimate pCO 2 (N=69; R2 = 0.80). Our results also illustrate the complexity of DOM temporal dynamics in the lower Amazon River where the occurrence of extreme high and low discharge due to factors such as El Niño, can significantly alter the expected seasonal oscillation, as was the case during this study period. The ability to remotely assess both DOC and pCO 2 from CDOM optical properties highlight the importance of using remote sensing data for monitoring carbon dynamics in large running water systems worldwide.« less

Authors:
ORCiD logo; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1455302
Report Number(s):
PNNL-SA-131638
Journal ID: ISSN 1094-4087; OPEXFF
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Optics Express; Journal Volume: 26; Journal Issue: 14
Country of Publication:
United States
Language:
English
Subject:
Amazon; aquatic; biogeochemistry; carbon cycling; chromophoric; climate change; coastal; CDOM; chlorophyll; carbon dioxide; continuum; dissolved organic carbon; ecosystem; emissions; exchange; flux; greenhouse gas; interface; optical; organic matter; outgassing; remote sensing; river; satellite; terrestial aquatic interface; tidal river; tidal

Citation Formats

Valerio, Aline de Matos, Kampel, Milton, Vantrepotte, Vincent, Ward, Nicholas D., Sawakuchi, Henrique Oliveira, Less, Diani Fernanda Da Silva, Neu, Vania, Cunha, Alan, and Richey, Jeffrey. Using CDOM optical properties for estimating DOC concentrations and pCO2 in the Lower Amazon River. United States: N. p., 2018. Web. doi:10.1364/OE.26.00A657.
Valerio, Aline de Matos, Kampel, Milton, Vantrepotte, Vincent, Ward, Nicholas D., Sawakuchi, Henrique Oliveira, Less, Diani Fernanda Da Silva, Neu, Vania, Cunha, Alan, & Richey, Jeffrey. Using CDOM optical properties for estimating DOC concentrations and pCO2 in the Lower Amazon River. United States. doi:10.1364/OE.26.00A657.
Valerio, Aline de Matos, Kampel, Milton, Vantrepotte, Vincent, Ward, Nicholas D., Sawakuchi, Henrique Oliveira, Less, Diani Fernanda Da Silva, Neu, Vania, Cunha, Alan, and Richey, Jeffrey. Mon . "Using CDOM optical properties for estimating DOC concentrations and pCO2 in the Lower Amazon River". United States. doi:10.1364/OE.26.00A657.
@article{osti_1455302,
title = {Using CDOM optical properties for estimating DOC concentrations and pCO2 in the Lower Amazon River},
author = {Valerio, Aline de Matos and Kampel, Milton and Vantrepotte, Vincent and Ward, Nicholas D. and Sawakuchi, Henrique Oliveira and Less, Diani Fernanda Da Silva and Neu, Vania and Cunha, Alan and Richey, Jeffrey},
abstractNote = {Colored dissolved organic matter (CDOM) is largely responsible for the optical properties of freshwaters and coastal areas and can be used as a proxy to assess the non-optical carbon content as the dissolved organic carbon (DOC) and the partial pressure of carbon dioxide (pCO2). Nevertheless, riverine studies that explores the former relationship are more challenging due to the spectral mixture caused by the high content of inorganic materials in the suspended sediment. Here we evaluate the spatial-temporal variability of CDOM, DOC and pCO2, as well as the potential of CDOM absorption coefficient (aCDOM(412)) for estimating DOC concentration and pCO2 along the lower Amazon River. Our results revealed differences in the dissolved organic matter (DOM) quality between clear water (CW) tributaries and the Amazon River mainstem. A linear relationship between DOC and CDOM was observed when tributaries and mainstem are evaluated separately (Amazon waters: N=42, R2=0.74; CW: N= 13, R2 = 0.57). However, this linear relationship was not observed during periods of higher rainfall and river discharge, requiring a model specific to these time periods to be developed (N = 25, R2 = 0.58). A strong linear positive relation was found between aCDOM(412) and pCO2( N=69, R2=0.65) along the lower river. pCO2 was less affected by the optical difference between tributaries and mainstem water or by the presence of higher hygrometric conditions when compared to CDOM to DOC relationships. Including the river water temperature in the model improves our ability to estimate pCO2 (N=69; R2 = 0.80). Our results also illustrate the complexity of DOM temporal dynamics in the lower Amazon River where the occurrence of extreme high and low discharge due to factors such as El Niño, can significantly alter the expected seasonal oscillation, as was the case during this study period. The ability to remotely assess both DOC and pCO2 from CDOM optical properties highlight the importance of using remote sensing data for monitoring carbon dynamics in large running water systems worldwide.},
doi = {10.1364/OE.26.00A657},
journal = {Optics Express},
number = 14,
volume = 26,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2018},
month = {Mon Jan 01 00:00:00 EST 2018}
}