scholarly journals The dark portion of the Mediterranean Sea is a bioreactor of organic matter cycling

2012 ◽  
Vol 26 (2) ◽  
pp. n/a-n/a ◽  
Author(s):  
G. M. Luna ◽  
S. Bianchelli ◽  
F. Decembrini ◽  
E. De Domenico ◽  
R. Danovaro ◽  
...  
Keyword(s):  
Organic Matter ◽  
Mediterranean Sea ◽  
Organic Matter Cycling ◽  
The Mediterranean ◽  
Dark Portion

scholarly journals A Two-Component Parameterization of Marine Ice Nucleating Particles Based on Seawater Biology and Sea Spray Aerosol Measurements in the Mediterranean Sea

2020 ◽  
Author(s):  
Jonathan V. Trueblood ◽  
Alesia Nicosia ◽  
Anja Engel ◽  
Birthe Zäncker ◽  
Matteo Rinaldi ◽  
...  
Keyword(s):  
Organic Matter ◽  
Mediterranean Sea ◽  
Biological Properties ◽  
Organic Content ◽  
Water Soluble ◽  
Sea Spray ◽  
Surface Microlayer ◽  
Natural Seawater ◽  
Order Of Magnitude ◽  
The Mediterranean

Abstract. Ice nucleating particles (INP) have a large impact on the climate-relevant properties of clouds over the oceans. Studies have shown that sea spray aerosols (SSA), produced upon bursting of bubbles at the ocean surface, can be an important source of marine INP, particularly during periods of enhanced biological productivity. Recent mesocosm experiments using natural seawater spiked with nutrients have revealed that marine INP are derived from two separate classes of organic matter in SSA. Despite this finding, existing parameterizations for marine INP abundance are based solely on single variables such as total organic carbon (TOC) or SSA surface area, which may mask specific trends in the separate classes of INPs. The goal of this paper is to improve the understanding of the connection between ocean biology and marine INP abundance by reporting results from a field study and proposing a new parameterization of marine INP that accounts for the two associated classes of organic matter. The PEACETIME cruise took place from May 10 to June 10, 2017 in the Mediterranean Sea. Throughout the cruise, INP concentrations in the surface microlayer (SML) and in SSA produced using a plunging aquarium apparatus were continuously monitored while surface seawater (SSW) and SML biological properties were measured in parallel. The organic content of artificially generated SSA was also evaluated. A dust wet deposition event that occurred during the cruise increased the INP concentrations measured in the SML by an order of magnitude, in line with increases of iron in the SML and bacterial abundances. Increases of INPs in marine SSA (INPSSA) were not observed before a delay of three days compared to increases in the SML, and are likely a result of a strong influence of bulk SSW INP for the temperatures investigated (T = −18 °C for SSA, T = −16 °C for SSW). Results confirmed that INPSSA are divided into two classes depending on their associated organic matter. Here we find that warm (T ≥ −22 °C) INPSSA concentrations are correlated with water soluble organic matter in the SSA, but also to SSW parameters (POCSSW INPSSW,−16 °C) while cold INPSSA (T 

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 A two-component parameterization of marine ice-nucleating particles based on seawater biology and sea spray aerosol measurements in the Mediterranean Sea

2021 ◽  
Vol 21 (6) ◽  
pp. 4659-4676
Author(s):  
Jonathan V. Trueblood ◽  
Alessia Nicosia ◽  
Anja Engel ◽  
Birthe Zäncker ◽  
Matteo Rinaldi ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Mediterranean Sea ◽  
Water Soluble ◽  
Component Model ◽  
Sea Spray ◽  
Surface Microlayer ◽  
Model Based ◽  
Two Component ◽  
The Mediterranean

Abstract. Ice-nucleating particles (INPs) have a large impact on the climate-relevant properties of clouds over the oceans. Studies have shown that sea spray aerosols (SSAs), produced upon bursting of bubbles at the ocean surface, can be an important source of marine INPs, particularly during periods of enhanced biological productivity. Recent mesocosm experiments using natural seawater spiked with nutrients have revealed that marine INPs are derived from two separate classes of organic matter in SSAs. Despite this finding, existing parameterizations for marine INP abundance are based solely on single variables such as SSA organic carbon (OC) or SSA surface area, which may mask specific trends in the separate classes of INP. The goal of this paper is to improve the understanding of the connection between ocean biology and marine INP abundance by reporting results from a field study and proposing a new parameterization of marine INPs that accounts for the two associated classes of organic matter. The PEACETIME cruise took place from 10 May to 10 June 2017 in the Mediterranean Sea. Throughout the cruise, INP concentrations in the surface microlayer (INPSML) and in SSAs (INPSSA) produced using a plunging aquarium apparatus were continuously monitored while surface seawater (SSW) and SML biological properties were measured in parallel. The organic content of artificially generated SSAs was also evaluated. INPSML concentrations were found to be lower than those reported in the literature, presumably due to the oligotrophic nature of the Mediterranean Sea. A dust wet deposition event that occurred during the cruise increased the INP concentrations measured in the SML by an order of magnitude, in line with increases in iron in the SML and bacterial abundances. Increases in INPSSA were not observed until after a delay of 3 days compared to increases in the SML and are likely a result of a strong influence of bulk SSW INPs for the temperatures investigated (T=-18 ∘C for SSAs, T=-15 ∘C for SSW). Results confirmed that INPSSA are divided into two classes depending on their associated organic matter. Here we find that warm (T≥-22 ∘C) INPSSA concentrations are correlated with water-soluble organic matter (WSOC) in the SSAs, but also with SSW parameters (particulate organic carbon, POCSSW and INPSSW,-16C) while cold INPSSA (T<-22 ∘C) are correlated with SSA water-insoluble organic carbon (WIOC) and SML dissolved organic carbon (DOC) concentrations. A relationship was also found between cold INPSSA and SSW nano- and microphytoplankton cell abundances, indicating that these species might be a source of water-insoluble organic matter with surfactant properties and specific IN activities. Guided by these results, we formulated and tested multiple parameterizations for the abundance of INPs in marine SSAs, including a single-component model based on POCSSW and a two-component model based on SSA WIOC and OC. We also altered a previous model based on OCSSA content to account for oligotrophy of the Mediterranean Sea. We then compared this formulation with the previous models. This new parameterization should improve attempts to incorporate marine INP emissions into numerical models.

scholarly journals Stable carbon isotope gradients in benthic foraminifera as proxy for organic carbon fluxes in the Mediterranean Sea

2016 ◽  
Vol 13 (23) ◽  
pp. 6385-6404 ◽  
Author(s):  
Marc Theodor ◽  
Gerhard Schmiedl ◽  
Frans Jorissen ◽  
Andreas Mackensen
Keyword(s):  
Organic Matter ◽  
Transfer Function ◽  
Primary Production ◽  
Mediterranean Sea ◽  
Pore Water ◽  
Benthic Foraminifera ◽  
Stable Carbon Isotope ◽  
Aegean Sea ◽  
Stable Carbon ◽  
The Mediterranean

Abstract. We have determined stable carbon isotope ratios of epifaunal and shallow infaunal benthic foraminifera in the Mediterranean Sea to relate the inferred gradient of pore water δ13CDIC to varying trophic conditions. This is a prerequisite for developing this difference into a potential transfer function for organic matter flux rates. The data set is based on samples retrieved from a well-defined bathymetric range (400–1500 m water depth) of sub-basins in the western, central, and eastern Mediterranean Sea. Regional contrasts in organic matter fluxes and associated δ13CDIC of pore water are recorded by the δ13C difference (Δδ13CUmed-Epi) between the shallow infaunal Uvigerina mediterranea and epifaunal species (Planulina ariminensis, Cibicidoides pachydermus, Cibicides lobatulus). Within epifaunal taxa, the highest δ13C values are recorded for P. ariminensis, providing the best indicator for bottom water δ13CDIC. In contrast, C. pachydermus reveals minor pore water effects at the more eutrophic sites. Because of ontogenetic trends in the δ13C signal of U. mediterranea of up to 1.04 ‰, only tests larger than 600 µm were used for the development of the transfer function. The recorded differences in the δ13C values of U. mediterranea and epifaunal taxa (Δδ13CUmed-Epi) range from −0.46 to −2.13 ‰, with generally higher offsets at more eutrophic sites. The measured δ13C differences are related to site-specific differences in microhabitat, depth of the principal sedimentary redox boundary, and TOC content of the ambient sediment. The Δδ13CUmed-Epi values reveal a consistent relation to Corg fluxes estimated from satellite-derived surface water primary production in open-marine settings of the Alboran Sea, Mallorca Channel, Strait of Sicily, and southern Aegean Sea. In contrast, Δδ13CUmed-Epi values in areas affected by intense resuspension and riverine organic matter sources of the northern to central Aegean Sea and the canyon systems of the Gulf of Lion suggest higher Corg fluxes compared to the values based on recent primary production. Taking regional biases and uncertainties into account, we establish a first Δδ13CUmed-Epi-based transfer function for Corg fluxes for the Mediterranean Sea.

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.

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