skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Assessing chromophoric dissolved organic matter (CDOM) distribution, stocks, and fluxes in Apalachicola Bay using combined field, VIIRS ocean color, and model observations

Abstract

Understanding the role of estuarine-carbon fluxes is essential to improve estimates of the global carbon budget. Dissolved organic matter (DOM) plays an important role in aquatic carbon cycling. Here, the chromophoric fraction of DOM (CDOM) can be readily detected via in situ and remotely-sensed optical measurements. DOM properties, including CDOM absorption coefficient at 412 nm (a g412) and dissolved organic carbon (DOC) concentrations were examined in Apalachicola Bay, a national estuarine research reserve located in the northeast Gulf of Mexico, using in situ and satellite observations during the spring and fall of 2015. Synoptic and accurate representation of estuarine-scale processes using satellite ocean color imagery necessitates the removal of atmospheric contribu- tion (~90%) to signals received by satellite sensors to successfully link to in situ observations. Three atmospheric correction schemes (e.g., Standard NIR correction, Iterative NIR correction, and SWIR correction) were tested first to find a suitable correction scheme for the VIIRS imagery in low to moderately turbid Apalachicola Bay. The iterative NIR correction performed well, and validation showed high correlation (R 2 = 0.95, N = 25) against in situ light measurements. A VIIRS-based CDOM algorithm was developed (R 2 = 0.87, N = 9) and validated (R 2more » = 0.76, N = 20, RMSE = 0.29 m -1) against in situ observations. Subsequently, ag412 was used as a proxy of DOC in March (DOC = 1.08 + 0.94 × a g412,R 2 =0.88, N = 13)and in November (DOC= 1.61 + 1.33 × a g412, R 2 = 0.83, N = 24) to derive DOC maps that provided synoptic views of DOC distribution, sources, and their transport to the coastal waters during the wet and dry seasons. The estimated DOC stocks were ~3.71 × 10 6 kg C in March and ~4.07 × 10 6 kg C in November over an area of ~560 km2. Volume flux (out of the bay) almost doubled for March 24 (735 m 3 s -1) relative to November 4 (378 m 3 s -1). However, estimates of DOC fluxes exported out of the bay from model-derived currents and satellite-derived DOC were only marginally greater in March (0.163 × 10 6 kg C d -1) than in November (0.124 × 10 6 kg C d -1) and reflected greater DOC stocks in the fall. Finally, the combination of satellite-, field-, and model-based observations revealed the strong linkage between the Apalachicola River plume, a major source of DOM, and the overall hydrodynamic forcing that controlled distributions of CDOM abundance, DOC concentration, stocks, and fluxes in the bay.« less

Authors:
 [1];  [1];  [2];  [3];  [4];  [2];  [3];  [5]
  1. Louisiana State Univ., Baton Rouge, LA (United States)
  2. North Carolina State Univ., Raleigh, NC (United States)
  3. Univ. of Florida, Gainesville, FL (United States)
  4. Naval Research Lab., Stennis Space Centre, MS (United States)
  5. Univ. of Florida, Gainesville, FL (United States); Univ. of Florida, St. Augustine, FL (United States)
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1347848
Report Number(s):
PNNL-SA-124218
Journal ID: ISSN 0034-4257
Grant/Contract Number:
AC05-76RL01830
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Remote Sensing of Environment
Additional Journal Information:
Journal Volume: 191; Journal Issue: C; Journal ID: ISSN 0034-4257
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 54 ENVIRONMENTAL SCIENCES; satellite; remote sensing; CDOM; organic carbon; estuarine; flux; stock; aquatic; terrestrial; interface; ecosystem; Apalachicola Bay; atmospheric-correction; carbon stocks & fluxes; CDOM algorithm; DOC; VIIRS

Citation Formats

Joshi, Ishan D., D'Sa, Eurico J., Osburn, Christopher L., Bianchi, Thomas S., Ko, Dong S., Oviedo-Vargas, Diana, Arellano, Ana R., and Ward, Nicholas D. Assessing chromophoric dissolved organic matter (CDOM) distribution, stocks, and fluxes in Apalachicola Bay using combined field, VIIRS ocean color, and model observations. United States: N. p., 2017. Web. doi:10.1016/j.rse.2017.01.039.
Joshi, Ishan D., D'Sa, Eurico J., Osburn, Christopher L., Bianchi, Thomas S., Ko, Dong S., Oviedo-Vargas, Diana, Arellano, Ana R., & Ward, Nicholas D. Assessing chromophoric dissolved organic matter (CDOM) distribution, stocks, and fluxes in Apalachicola Bay using combined field, VIIRS ocean color, and model observations. United States. doi:10.1016/j.rse.2017.01.039.
Joshi, Ishan D., D'Sa, Eurico J., Osburn, Christopher L., Bianchi, Thomas S., Ko, Dong S., Oviedo-Vargas, Diana, Arellano, Ana R., and Ward, Nicholas D. Mon . "Assessing chromophoric dissolved organic matter (CDOM) distribution, stocks, and fluxes in Apalachicola Bay using combined field, VIIRS ocean color, and model observations". United States. doi:10.1016/j.rse.2017.01.039. https://www.osti.gov/servlets/purl/1347848.
@article{osti_1347848,
title = {Assessing chromophoric dissolved organic matter (CDOM) distribution, stocks, and fluxes in Apalachicola Bay using combined field, VIIRS ocean color, and model observations},
author = {Joshi, Ishan D. and D'Sa, Eurico J. and Osburn, Christopher L. and Bianchi, Thomas S. and Ko, Dong S. and Oviedo-Vargas, Diana and Arellano, Ana R. and Ward, Nicholas D.},
abstractNote = {Understanding the role of estuarine-carbon fluxes is essential to improve estimates of the global carbon budget. Dissolved organic matter (DOM) plays an important role in aquatic carbon cycling. Here, the chromophoric fraction of DOM (CDOM) can be readily detected via in situ and remotely-sensed optical measurements. DOM properties, including CDOM absorption coefficient at 412 nm (ag412) and dissolved organic carbon (DOC) concentrations were examined in Apalachicola Bay, a national estuarine research reserve located in the northeast Gulf of Mexico, using in situ and satellite observations during the spring and fall of 2015. Synoptic and accurate representation of estuarine-scale processes using satellite ocean color imagery necessitates the removal of atmospheric contribu- tion (~90%) to signals received by satellite sensors to successfully link to in situ observations. Three atmospheric correction schemes (e.g., Standard NIR correction, Iterative NIR correction, and SWIR correction) were tested first to find a suitable correction scheme for the VIIRS imagery in low to moderately turbid Apalachicola Bay. The iterative NIR correction performed well, and validation showed high correlation (R2 = 0.95, N = 25) against in situ light measurements. A VIIRS-based CDOM algorithm was developed (R2 = 0.87, N = 9) and validated (R2 = 0.76, N = 20, RMSE = 0.29 m-1) against in situ observations. Subsequently, ag412 was used as a proxy of DOC in March (DOC = 1.08 + 0.94 × ag412,R2 =0.88, N = 13)and in November (DOC= 1.61 + 1.33 × ag412, R2 = 0.83, N = 24) to derive DOC maps that provided synoptic views of DOC distribution, sources, and their transport to the coastal waters during the wet and dry seasons. The estimated DOC stocks were ~3.71 × 106 kg C in March and ~4.07 × 106 kg C in November over an area of ~560 km2. Volume flux (out of the bay) almost doubled for March 24 (735 m3 s-1) relative to November 4 (378 m3 s-1). However, estimates of DOC fluxes exported out of the bay from model-derived currents and satellite-derived DOC were only marginally greater in March (0.163 × 106 kg C d-1) than in November (0.124 × 106 kg C d-1) and reflected greater DOC stocks in the fall. Finally, the combination of satellite-, field-, and model-based observations revealed the strong linkage between the Apalachicola River plume, a major source of DOM, and the overall hydrodynamic forcing that controlled distributions of CDOM abundance, DOC concentration, stocks, and fluxes in the bay.},
doi = {10.1016/j.rse.2017.01.039},
journal = {Remote Sensing of Environment},
number = C,
volume = 191,
place = {United States},
year = {Mon Feb 06 00:00:00 EST 2017},
month = {Mon Feb 06 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 2works
Citation information provided by
Web of Science

Save / Share:
  • Using bio-optical estimates of gelbstoff and a few platinum measurements of dissolved organic carbon (DOC{sub pt}), a budget of the meridional flux of DOC and dissolved organic nitrogen (DON) across 36{degrees}25{prime}N in the North Atlantic is constructed from previous inverse models of water and element transport. Distinct southward subsurface fluxes of dissolved organic matter (DOM) within subducted shelf water, cabelled slope water, and overturned basin water are inferred. Within two cases of a positive gradient of DOC{sub pt} between terrestrial/shelf and offshore stocks, the net equatorward exports of O{sub 2} and DOC{sub pt} from the northern North Atlantic yield molarmore » ratios of 2.1 to 9.1, compared to the expected Redfield O{sub 2}/C ratio of 1.3. In the first case, 63% of the apparent oxygen utilization demands of the water column may be met by DOC, instead of only 14% in the second scenario, preserving a role for falling particles in the sea. With a DOC/DON ratio of 10, the larger net southward export of DON across 36{degrees}25{prime}N balances the postulated net northward input of 1.7 x 10{sup 3} kg NO{sub 3} s{sup {minus}1} of unutilized nitrate within the Gulf Stream. Without an enhanced supply of DOM from the shelves, a zero seaward gradient of DOM in the third case suggests that none of the poleward nitrate flux is returned southward as DON, but instead a net poleward flux of DON prevails as well. The authors present estimates are confounded, however, by the seasonal and multiyear variability of sinking processes in the North Atlantic. Future active and passive remote sensors, field programs, and simulation models must now discriminate between particulate and dissolved components of surface color signals to verify the importance of both continental margins and DOM in global biogeochemical cycles. 98 refs., 4 figs., 4 tabs.« less
  • Cited by 2
  • Benthic fluxes of dissolved organic carbon (DOC) were measured over an annual cycle at two contrasting sites in Chesapeake Bay. At an organic-rich, sulfidic site in the mesohaline portion of the Bay (site M) DOC fluxes from the sediments ranged from 1.4 to 2.9 mmol/m[sup 2]/d. Measured benthic DOC fluxes at site M corresponded to [approximately]3-13% of the depth-integrated benthic C remineralization rates ([Sigma]OCR), and agreed well with calculated diffusive DOC fluxes based on porewater DOC profiles. This agreement suggests that DOC fluxes from site M sediments were likely controlled by molecular diffusion. The second site that was studied ismore » a heavily bioturbated site in the southern Bay (site S). The activity of macrobenthos did not appear to enhance DOC fluxes from these sediments, since measured benthic DOC fluxes (>0.5 mmol/m[sup 2]/d) were lower than those at site M. The ratios of benthic DOC fluxes to [Sigma]OCR values at site S were also slightly smaller than those observed at site M. Benthic DOC fluxes from Chesapeake Bay sediments do not appear to significantly affect the transport of DOC through this estuary, although uncertainties in the reactivity of DOC in estuaries makes this conclusion somewhat tentative at this time. However, when these results are used to make a lower limit estimate of the globally integrated benthic DOC flux from marine sediments, a value similar to that previously calculated by Burdige et al. is obtained. This observation further supports suggestions in this paper about the importance of benthic DOC fluxes in the oceanic C cycle.« less
  • The authors present evidence suggesting that only a portion of the dissolved organic carbon (DOC) in the seawater analyzed previously by Williams and Druffel (1987) was oxidized by the UV-radiation method. High temperature catalytic (HTC) methods (Sugimura and Suzuki, 1988) used to reoxidize the central North Pacific gyre water samples reveal that the total DOC (DOC{sub HTC}) is about twice that of the UV-oxidizable DOC (DOC{sub UV}). Indications from the original study suggest that this additional DOC contains higher concentrations of radiocarbon than in the DOC{sub UV} (Williams and Druffel, 1987). This evidence implies that DOC is older and thusmore » more refractory with respect to biological utilization, yet is more chemically reactive with respect to photooxidation, than the fraction resistant to UV (DOC{sub res}). The authors report accelerator mass spectrometry (AMS) {Delta}{sup 14}C measurements of humic, fulvic and hydrophilic acid fractions isolated from water collected at 180 m in the North Pacific (19{degree}N, 158{degree}W) using XAD macroreticular resins. {Delta}{sup 14} values of the humic material are less than those of DOC{sub UV} from a similar depth 1,200 km further north (Williams and Druffel, 1987) indicating that these humic substances are part of the old recycled DOC{sub UV} in the ocean.« less
  • Copper-dissolved organic matter binding is observed for Black Lake, NC, fulvic acid by measuring free metal with a copper ion selective electrode (ISE) and the unbound organic ligand by fluorescence. The two detectors agree at low, aquatic levels of copper loading; a discrepancy at high copper concentrations may result from precipitation or inappropriate assumptions about the fluorescence technique. Complementary error properties of combined detection provide low-error titration data over a wider range of pH and pCu than either detector alone. Calibration by ISE is more reliable than curve fitting for relating fluorescence to bound copper concentrations. 24 references, 6 figures.