scholarly journals Deep-ocean dissolved organic matter reactivity along the Mediterranean Sea: does size matter?

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Alba María Martínez-Pérez ◽  
Xosé Antón Álvarez-Salgado ◽  
Javier Arístegui ◽  
Mar Nieto-Cid
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Mediterranean Sea ◽  
Deep Ocean ◽  
The Mediterranean ◽  
Size Matter

scholarly journals Molecular composition of dissolved organic matter in the Mediterranean Sea

2017 ◽  
Vol 62 (6) ◽  
pp. 2699-2712 ◽  
Author(s):  
Alba María Martínez-Pérez ◽  
Helena Osterholz ◽  
Mar Nieto-Cid ◽  
Marta Álvarez ◽  
Thorsten Dittmar ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Mediterranean Sea ◽  
Molecular Composition ◽  
The Mediterranean

scholarly journals The composition and flux of particulate and dissolved carbohydrates from the Rhone River into the Mediterranean Sea

2012 ◽  
Vol 9 (5) ◽  
pp. 1827-1844 ◽  
Author(s):  
C. Panagiotopoulos ◽  
R. Sempéré ◽  
J. Para ◽  
P. Raimbault ◽  
C. Rabouille ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Mediterranean Sea ◽  
Terrestrial Organic Matter ◽  
Rhône River ◽  
Rhone River ◽  
Northwestern Mediterranean Sea ◽  
The Mediterranean ◽  
Northwestern Mediterranean ◽  
Annual Flux

Abstract. Carbohydrates are important components of the carbon cycle and may be used as indicators of the origin and the diagenetic status of marine and terrestrial organic matter. Nevertheless, comprehensive studies of both particulate (PCHO) and dissolved (DCHO) carbohydrates in rivers are scarce, and the seasonal and interannual variability of these compounds in relationship to the bulk particulate (POM) and dissolved organic matter (DOM) is largely unknown. For the period 2007–2009, we sampled once per month POM and DOM and measured the total suspended matter (TSM), POM, DOM, PCHO, and DCHO for the Rhône River, which flows into the Mediterranean Sea. Using these measurements, we estimated for the above parameters annual fluxes for the period 2007–2009. The estimated carbohydrate fluxes averaged 0.064 ± 0.026 × 1010 moles C yr−1 for PCHO and 0.042 ± 0.008 × 1010 moles C yr−1 DCHO, representing 6 % and 7 % of the annual flux of POC and DOC, respectively. During flood and low-water periods, POM variations were reflected into the PCHO pool, whereas this was not observed for DOC and DCHO, indicating a decoupling between particulate and dissolved organic matter. Our results also showed that flood and low-water periods may be differentiated using the ratios PCHO/DCHO and POC/DOC, which had a significant relationship. Based on the carbohydrate abundances in both the PCHO and DCHO pools, we conclude that this material mainly derives from allochthonous sources (vascular plants, bacteria and soils). Moreover, during flood events, an enrichment in mannose in POM was observed, probably reflecting an angiosperm source (leaves or grasses). By expanding our results to the northwestern Mediterranean Sea (Gulf of Lions), we found that the total organic carbon (TOC) fluxes of the Rhône River accounted for ~1 % of the standing stock of seawater TOC. Considering that glucose is the most abundant carbohydrate in both particulate and dissolved organic matter pools (~33 %), its annual flux in the northwestern Mediterranean Sea was estimated to 3.8 × 108 moles glucose.

scholarly journals The composition and flux of particulate and dissolved carbohydrates from the Rhône River into the Mediterranean Sea

2011 ◽  
Vol 8 (6) ◽  
pp. 11165-11213 ◽  
Author(s):  
C. Panagiotopoulos ◽  
R. Sempéré ◽  
J. Para ◽  
P. Raimbault ◽  
C. Rabouille ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Mediterranean Sea ◽  
Terrestrial Organic Matter ◽  
Rhône River ◽  
Rhone River ◽  
Northwestern Mediterranean Sea ◽  
The Mediterranean ◽  
Northwestern Mediterranean ◽  
Annual Flux

Abstract. Carbohydrates are important components of the carbon cycle and may be used as indicators of the origin and the diagenetic status of marine and terrestrial organic matter. Nevertheless, comprehensive studies of both particulate (PCHO) and dissolved (DCHO) carbohydrates in rivers are scarce, and the seasonal and interannual variability of these compounds in relationship to the bulk particulate (POM) and dissolved organic matter (DOM) is largely unknown. For the period 2007–2009, we sampled once per month POM and DOM and measured the total suspended matter (TSM), POM, DOM, PCHO, and DCHO for the Rhône River, which flows into the Mediterranean Sea. Using these measurements, we estimated for the above parameters annual fluxes for the period 2001–2010. The estimated carbohydrate fluxes averaged 0.061±0.043×1010 moles Cy−1 for PCHO and 0.041±0.0062×1010 moles Cy−1 DCHO, representing 8% and 7% of the annual flux of POC and DOC, respectively. During flood and low-water periods, POM variations were reflected into the PCHO pool, whereas this was not observed for DOC and DCHO, indicating a decoupling between particulate and dissolved organic matter. Our results also showed that flood and low-water periods may be differentiated using the ratios PCHO/DCHO and POC/DOC, which had a significant linear relationship. Based on the carbohydrate abundances in both the PCHO and DCHO pools, we conclude that this material mainly derives from allochthonous sources (vascular plants, bacteria and soils). Moreover, during flood events, an enrichment in mannose in POM was observed, probably reflecting an angiosperm source (leaves or grasses). By expanding our results to the northwestern Mediterranean Sea (Gulf of Lions), we found that the total organic carbon (TOC) fluxes of the Rhône River accounted for ~1% of the standing stock of seawater TOC. Considering that glucose is the most abundant carbohydrate in both particulate and dissolved organic matter pools (~33%), its annual flux in the northwestern Mediterranean Sea was estimated to 19.2×108 moles glucose-C.

scholarly journals Radiative transfer modeling with BGC-Argo float data in the Mediterranean Sea

2021 ◽  
Author(s):  
Elena Terzić ◽  
Arnau Miró ◽  
Paolo Lazzari ◽  
Emanuele Organelli ◽  
Fabrizio D'Ortenzio
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Radiative Transfer ◽  
Dissolved Organic Matter ◽  
Water Absorption ◽  
Mediterranean Sea ◽  
Pure Water ◽  
Colored Dissolved Organic Matter ◽  
Water Constituents ◽  
The Mediterranean

Abstract. A radiative transfer model was parameterized and validated using Biogeochemical Argo float data acquired between 2012 and 2017 across the Mediterranean Sea. Fluorescence-derived chlorophyll a concentration, particle backscattering at 700 nm and fluorescence of colored dissolved organic matter were used to parametrize the light absorption and scattering coefficients of the optically significant water constituents (pure water, non-algal particles, colored dissolved organic matter and phytoplankton). The model was validated with in-situ downwelling irradiance profiles and irradiance-derived apparent optical properties from satellite data, such as the diffuse attenuation coefficients and remote sensing reflectance. To the authors' knowledge, this is the first time that a three-platform comparison of such kind is performed between model, floats and satellites. Results showed that by using regional parameterizations that are not only related to chlorophyll concentration and vertical distribution, the model was able to capture a more accurate spectral response in the examined wavelength range compared to chlorophyll-related (or Case 1) optical models. When using alternative models that incorporated also measurements of colored dissolved organic matter fluorescence or particulate optical backscattering, the model skill increased at all examined wavelengths. A series of upgrades, such as the inclusion of temperature and salinity data for the modification of the pure water absorption spectra, a refined pure water absorption model, as well as the correction of regional algorithms that had overestimated the pure water contribution in the blue, all contributed to improve the model performance. Finally, using a multi-spectral optical configuration enabled to estimate also the relative contribution of separate water constituents in the examined spectral range. Simulations including non-algal particles and colored dissolved organic matter performed up to 60 % and 76 % better than when considering the optical properties of pure seawater alone. Moreover, a simulation including phytoplankton absorption resulted in an error reduction of up to 43 %, especially at 412 nm and with a more uniform response at the wavelengths considered. Such studies can therefore also tackle the bio-optically anomalous nature of the Mediterranean Sea, and show that non-chlorophyll-related constituents (i.e. non-algal particles and colored dissolved organic matter) can substantially modulate the underwater light field in the blue.

scholarly journals Linking optical and molecular signatures of dissolved organic matter in the Mediterranean Sea

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Alba María Martínez-Pérez ◽  
Mar Nieto-Cid ◽  
Helena Osterholz ◽  
Teresa S. Catalá ◽  
Isabel Reche ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Mediterranean Sea ◽  
Molecular Signatures ◽  
The Mediterranean

Efficient export of carbon to the deep ocean through dissolved organic matter

Nature ◽  
2005 ◽  
Vol 433 (7022) ◽  
pp. 142-145 ◽  
Author(s):  
Charles S. Hopkinson ◽  
Joseph J. Vallino
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Deep Ocean
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