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Book ; Online: Estimating the seasonal impact of optically significant water constituents on surface heating rates in the Western Baltic Sea

Cahill, Bronwyn E. / Kowalczuk, Piotr / Kritten, Lena / Gräwe, Ulf / Wilkin, John / Fischer, Jürgen

eISSN:

2023

Abstract: Heating rates induced by optically significant water constituents (OSCs), e.g. phytoplankton and coloured dissolved organic matter (CDOM), contribute to the seasonal modulation of thermal energy fluxes across the ocean–atmosphere interface in coastal and ...

Abstract	Heating rates induced by optically significant water constituents (OSCs), e.g. phytoplankton and coloured dissolved organic matter (CDOM), contribute to the seasonal modulation of thermal energy fluxes across the ocean–atmosphere interface in coastal and regional shelf seas. This is investigated in the western Baltic Sea, a marginal sea characterised by considerable inputs of freshwater carrying nutrients and CDOM and by complex bio-optical and hydrodynamic processes. Using a coupled bio-optical ocean model (ROMS–Bio-Optic), the inherent optical properties of different OSCs are modelled under varying environmental conditions, and the underwater light field is spectrally resolved in a dynamic ocean. We estimate the relative contribution of these OSCs to the divergence of the heat flux and heating rates and find that, while phytoplankton and CDOM both contribute to surface heating in summer, phytoplankton dominates the OSC contribution to heating in spring, and CDOM dominates the OSC contribution to heating in autumn. The study shows that seasonal and spatial changes in OSCs in the western Baltic Sea have a small but noticeable impact on radiative heating in surface waters and consequences for the exchange of energy fluxes across the air–sea interface and the distribution of heat within the water column. In the Pomeranian Bight, where riverine influx of CDOM is strongest, water-constituent-induced heating rates in surface waters in 2018 are estimated to be between 0.8 and 0.9 K m −1 d −1 in spring and summer, predominantly as a result of increased absorption by phytoplankton and CDOM. Further offshore, OSC-induced heating rates during the same periods are estimated to be between 0.4 and 0.8 K m −1 d −1 . Warmer surface waters are balanced by cooler subsurface waters. Surface heat fluxes (latent, sensible and longwave) respond to warmer sea surface temperatures, with a small increase in heat loss to the atmosphere of 5 W m −2 during the period April to September. We find relatively good agreement between our ...
Subject code	333 ; 551
Language	English
Publishing date	2023-07-13
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Estimating the seasonal impact of optically significant water constituents on surface heating rates in the western Baltic Sea

Cahill, Bronwyn E. / Kowalczuk, Piotr / Kritten, Lena / Gräwe, Ulf / Wilkin, John / Fischer, Jürgen

eISSN: 1726-4189

2023

Abstract	Heating rates induced by optically significant water constituents (OSCs), e.g. phytoplankton and coloured dissolved organic matter (CDOM), contribute to the seasonal modulation of thermal energy fluxes across the ocean–atmosphere interface in coastal and regional shelf seas. This is investigated in the western Baltic Sea, a marginal sea characterised by considerable inputs of freshwater carrying nutrients and CDOM and by complex bio-optical and hydrodynamic processes. Using a coupled bio-optical ocean model (ROMS–Bio-Optic), the inherent optical properties of different OSCs are modelled under varying environmental conditions, and the underwater light field is spectrally resolved in a dynamic ocean. We estimate the relative contribution of these OSCs to the divergence of the heat flux and heating rates and find that, while phytoplankton and CDOM both contribute to surface heating in summer, phytoplankton dominates the OSC contribution to heating in spring, and CDOM dominates the OSC contribution to heating in autumn. The study shows that seasonal and spatial changes in OSCs in the western Baltic Sea have a small but noticeable impact on radiative heating in surface waters and consequences for the exchange of energy fluxes across the air–sea interface and the distribution of heat within the water column. In the Pomeranian Bight, where riverine influx of CDOM is strongest, water-constituent-induced heating rates in surface waters in 2018 are estimated to be between 0.8 and 0.9 K m −1 d −1 in spring and summer, predominantly as a result of increased absorption by phytoplankton and CDOM. Further offshore, OSC-induced heating rates during the same periods are estimated to be between 0.4 and 0.8 K m −1 d −1 . Warmer surface waters are balanced by cooler subsurface waters. Surface heat fluxes (latent, sensible and longwave) respond to warmer sea surface temperatures, with a small increase in heat loss to the atmosphere of 5 W m −2 during the period April to September. We find relatively good agreement between our ...
Subject code	333 ; 551
Language	English
Publishing date	2023-07-13
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Radiative Transfer Modeling With Biogeochemical‐Argo Float Data in the Mediterranean Sea

Terzić, Elena / Miró, Arnau / Organelli, Emanuele / Kowalczuk, Piotr / D’Ortenzio, Fabrizio / Lazzari, Paolo

Journal of geophysical research. 2021 Oct., v. 126, no. 10

2021

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, particulate optical backscattering at 700 nm, ... ...

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, particulate optical backscattering at 700 nm, and fluorescence of chromophoric dissolved organic matter (CDOM) were used to parametrize the light absorption and scattering coefficients of the optically significant water constituents (such as pure water, non‐algal particles, CDOM, and phytoplankton). The model was validated with in situ downwelling irradiance profiles and apparent optical properties derived both from irradiance profiles and satellite data, such as the diffuse attenuation coefficients and remote sensing reflectance. 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 CDOM fluorescence or particulate optical backscattering, the model skill increased at all examined wavelengths. Finally, using a multi‐spectral optical configuration also enabled the estimation of the relative contribution of separate water constituents in the examined spectral range. Simulations including non‐algal particles and CDOM performed up to 61% and 79% better than when considering the optical properties of pure seawater alone. Moreover, a simulation including phytoplankton light absorption resulted in an error reduction of up to 42%, especially at 412 nm and with a more uniform response at the wavelengths considered.
Keywords	absorption ; chlorophyll ; dissolved organic matter ; fluorescence ; geophysics ; light intensity ; models ; phytoplankton ; radiative transfer ; reflectance ; remote sensing ; research ; seawater ; spatial distribution ; wavelengths ; Mediterranean Sea
Language	English
Dates of publication	2021-10
Publishing place	John Wiley & Sons, Ltd
Document type	Article
Note	JOURNAL ARTICLE
ZDB-ID	161667-5
ISSN	2169-9291 ; 2169-9275 ; 0148-0227 ; 0196-2256
ISSN (online)	2169-9291
ISSN	2169-9275 ; 0148-0227 ; 0196-2256
DOI	10.1029/2021JC017690
Database	NAL-Catalogue (AGRICOLA)

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Article: Radiative Transfer Modeling With Biogeochemical-Argo Float Data in the Mediterranean Sea.

Terzić, Elena / Miró, Arnau / Organelli, Emanuele / Kowalczuk, Piotr / D'Ortenzio, Fabrizio / Lazzari, Paolo

Journal of geophysical research. Oceans

2021 Volume 126, Issue 10, Page(s) e2021JC017690

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 ... ...

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
Language	English
Publishing date	2021-10-18
Publishing country	United States
Document type	Journal Article
ZDB-ID	161667-5
ISSN	2169-9291 ; 2169-9275 ; 0148-0227 ; 0196-2256
ISSN (online)	2169-9291
ISSN	2169-9275 ; 0148-0227 ; 0196-2256
DOI	10.1029/2021JC017690
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Book ; Online: Inherent optical properties and optical characteristics of dissolved organic and particulate matter in an Arctic fjord (Storfjorden, Svalbard) in early summer

Petit, Tristan / Hamre, Børge / Sandven, Håkon / Röttgers, Rüdiger / Kowalczuk, Piotr / Zablocka, Monika / Granskog, Mats

eISSN: 1812-0792

2021

Abstract: There have been considerable efforts to understand the hydrography of the Storfjorden fjord (Svalbard). A recurring winter polynya with large sea ice production makes it an important region of dense water formation at the scale of the Arctic Ocean. In ... ...

Abstract	There have been considerable efforts to understand the hydrography of the Storfjorden fjord (Svalbard). A recurring winter polynya with large sea ice production makes it an important region of dense water formation at the scale of the Arctic Ocean. In addition, this fjord is seasonally influenced by freshwater inputs from sea-ice melt and the surrounding islands of the Svalbard archipelago which impacts the hydrography. However, the understanding of factors controlling the optical properties of the waters in Storfjorden are lacking and are crucial for development of more accurate regional bio-optical models. Here, we present results from the first detailed optical field survey of Storfjorden conducted in early summer of 2020. In addition to the expected seasonal contribution from phytoplankton, we find that in early summer waters in Storfjorden are optically complex with a significant contribution from coloured dissolved organic matter (33–64 % of the non-water absorption at 443 nm) despite relatively low CDOM concentrations, and in the nearshore or near seabed from non-algal particles (up to 61 % of the non-water absorption at 550 nm). In surface waters, the spatial variability of light attenuation was mainly controlled by inorganic suspended matter originating from river runoff. A distinct subsurface maximum of light attenuation was largely driven by a subsurface phytoplankton bloom, controlled by stratification resulting from sea-ice melt. Lastly, the cold dense bottom waters of Storfjorden, from winter sea ice production, which periodically overflows into the Fram Strait, was found to contain elevated levels of both non-algal particles and dissolved organic matter, which is likely caused by the dense flows of the nepheloid layer interacting with the sea bed.
Subject code	551 ; 550
Language	English
Publishing date	2021-10-06
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Inherent optical properties of dissolved and particulate matter in an Arctic fjord (Storfjorden, Svalbard) in early summer

Petit, Tristan / Hamre, Børge / Sandven, Håkon / Röttgers, Rüdiger / Kowalczuk, Piotr / Zablocka, Monika / Granskog, Mats A.

eISSN: 1812-0792

2022

Abstract: There have been considerable efforts to understand the hydrography of Storfjorden (Svalbard). A recurring winter polynya with large sea ice production makes it an important region of dense water formation at the scale of the Arctic Ocean. In addition, ... ...

Abstract	There have been considerable efforts to understand the hydrography of Storfjorden (Svalbard). A recurring winter polynya with large sea ice production makes it an important region of dense water formation at the scale of the Arctic Ocean. In addition, this fjord is seasonally influenced by freshwater inputs from sea ice melt and the surrounding islands of the Svalbard archipelago, which impacts the hydrography. However, the understanding of factors controlling the optical properties of the waters in Storfjorden are lacking and are crucial for the development of more accurate regional bio-optical models. Here, we present results from the first detailed optical field survey of Storfjorden conducted in early summer of 2020. Our observations are based on spectrometric analysis of water samples and in situ vertical profiles with an absorption and attenuation meter, a fluorometer, and a conductivity, temperature, and depth (CTD) sensor. In addition to the expected seasonal contribution from phytoplankton, we find that in early summer waters in Storfjorden are optically complex with a significant contribution from coloured dissolved organic matter (CDOM, 33 %–64 % of the non-water absorption at 443 nm) despite relatively low CDOM concentrations and in the nearshore or near the seabed from non-algal particles (up to 61 % of the non-water absorption at 550 nm). In surface waters, the spatial variability of light attenuation was mainly controlled by inorganic suspended matter originating from river runoff. A distinct subsurface maximum of light attenuation was largely driven by a subsurface phytoplankton bloom, controlled by stratification resulting from sea ice melt. Lastly, the cold dense bottom waters of Storfjorden from winter sea ice production periodically overflows the sill at the mouth of the fjord and can thus reach the Fram Strait. It contained elevated levels of both non-algal particles and dissolved organic matter, which are likely caused by the dense flows of the nepheloid layer interacting with the sea bed.
Subject code	551
Language	English
Publishing date	2022-04-07
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Bio‐optical Properties of Surface Waters in the Atlantic Water Inflow Region off Spitsbergen (Arctic Ocean)

Kowalczuk, Piotr / Sagan, Sławomir / Makarewicz, Anna / Meler, Justyna / Borzycka, Karolina / Zabłocka, Monika / Zdun, Agnieszka / Konik, Marta / Darecki, Mirosław / Granskog, Mats A. / Pavlov, Alexey K.

Journal of geophysical research. 2019 Mar., v. 124, no. 3

2019

Abstract: Bio‐optical properties of surface waters were characterized off western and northern Spitsbergen in the summers of 2013, 2014, and 2015. We observed statistically significant year‐to‐year differences in spatial distribution of spectral absorption (a(λ)) ... ...

Abstract	Bio‐optical properties of surface waters were characterized off western and northern Spitsbergen in the summers of 2013, 2014, and 2015. We observed statistically significant year‐to‐year differences in spatial distribution of spectral absorption (a(λ)) and beam attenuation (c(λ)). Highest a(λ) and c(λ) were located in the frontal zone between water masses and co‐varied strongly with chlorophyll a fluorescence. Phytoplankton pigments dominated the absorption budget at 443 nm (50%). The contribution of chromophoric dissolved organic matter to total nonwater absorption was highest at 412 nm (42%), and detrital absorption contributed most at 550 nm (37%). Almost all inherent optical properties, except chromophoric dissolved organic matter, were highly correlated with the chlorophyll a concentration (Chla, R² > 0.81). Relationships between Chla and the particulate and phytoplankton pigments absorption coefficients at 443 and 676 nm were characterized by significant determination coefficients (R² > 0.73). The phytoplankton pigments line height absorption aLH(676) was found to be the most reliable optical proxy for determination of Chla, compared to total nonwater absorption, aₚg(676), and stimulated in situ chlorophyll a fluorescence intensity, ICₕₗₐ. In the presence of sea ice melt the water column was stratified and the vertical distribution of inherent optical properties was characterized by a surface minimum followed by a distinct subsurface maximum, aligned with a subsurface chlorophyll a maximum. We surmise that prevailing regional wind patterns affect sea ice and surface drift in central Fram Strait, and thus the location of sea ice meltwater, which affects the vertical stratification and occurrence of subsurface chlorophyll a maximum.
Keywords	absorption ; chlorophyll ; dissolved organic matter ; fluorescence ; geophysics ; phytoplankton ; research ; sea ice ; snowmelt ; spatial distribution ; wind ; Norway
Language	English
Dates of publication	2019-03
Size	p. 1964-1987.
Publishing place	John Wiley & Sons, Ltd
Document type	Article
Note	JOURNAL ARTICLE
ZDB-ID	161667-5
ISSN	2169-9291 ; 2169-9275 ; 0148-0227 ; 0196-2256
ISSN (online)	2169-9291
ISSN	2169-9275 ; 0148-0227 ; 0196-2256
DOI	10.1029/2018JC014529
Database	NAL-Catalogue (AGRICOLA)

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Book ; Online: Characteristics of chromophoric and fluorescent dissolved organic matter in the Nordic Seas

Makarewicz, Anna / Kowalczuk, Piotr / Sagan, Sławomir / Granskog, Mats A. / Pavlov, Alexey K. / Zdun, Agnieszka / Borzycka, Karolina / Zabłocka, Monika

eISSN: 1812-0792

2019

Abstract: Optical properties of chromophoric (CDOM) and fluorescent dissolved organic matter (FDOM) were characterized in the Nordic Seas including the West Spitsbergen Shelf during June–July 2013, 2014, and 2015. The CDOM absorption coefficient at 350 nm, a CDOM ( ...

Abstract	Optical properties of chromophoric (CDOM) and fluorescent dissolved organic matter (FDOM) were characterized in the Nordic Seas including the West Spitsbergen Shelf during June–July 2013, 2014, and 2015. The CDOM absorption coefficient at 350 nm, a CDOM (350) showed significant interannual variation ( T test, p < 0.00001). In 2013, the highest average a CDOM (350) values ( a CDOM (350) = 0.30 ± 0.12 m −1 ) were observed due to the influence of cold and low-salinity water from the Sørkapp Current (SC) in the southern part of the West Spitsbergen Shelf. In 2014, a CDOM (350) values were significantly lower ( T test, p < 0.00001) than in 2013 (average a CDOM (350) = 0.14 ± 0.06 m −1 ), which was associated with the dominance of warm and saline Atlantic Water (AW) in the region, while in 2015 intermediate CDOM absorption (average a CDOM (350) = 0.19 ± 0.05 m −1 ) was observed. In situ measurements of three FDOM components revealed that fluorescence intensity of protein-like FDOM dominated in the surface layer of the Nordic Seas. Concentrations of marine and terrestrial humic-like DOM were very low and distribution of those components was generally vertically homogenous in the upper ocean (0–100 m). Fluorescence of terrestrial and marine humic-like DOM decreased in surface waters (0–15 m) near the sea ice edge due to dilution of oceanic waters by sea ice meltwater. The vertical distribution of protein-like FDOM was characterized by a prominent subsurface maximum that matched the subsurface chlorophyll a maximum and was observed across the study area. The highest protein-like FDOM fluorescence was observed in the Norwegian Sea in the core of warm AW. There was a significant relationship between the protein-like fluorescence and chlorophyll a fluorescence ( R 2 = 0.65, p < 0.0001, n = 24 490), which suggests that phytoplankton was the primary source of protein-like DOM in the Nordic Seas and West Spitsbergen Shelf waters. Observed variability in selected spectral indices (spectral slope coefficient, S 300–600 , carbon-specific CDOM absorption coefficient at 254 and 350 nm, SUVA 254 , <math xmlns="http://www.w3.org/1998/Math/MathML" id="M32" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi>a</mi><mi mathvariant="normal">CDOM</mi><mo>*</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="33pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="eb9de09c197c725c3717629a33815e20"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="os-14-543-2018-ie00001.svg" width="33pt" height="15pt" src="os-14-543-2018-ie00001.png"/></svg:svg> (350)) and the nonlinear relationship between CDOM absorption and the spectral slope coefficient also indicate a dominant marine (autochthonous) source of CDOM and FDOM in the study area. Further, our data suggest that a CDOM (350) cannot be used to predict dissolved organic carbon (DOC) concentrations in the study region; however the slope coefficient ( S 300–600 ) shows some promise in being used.
Subject code	511 ; 333
Language	English
Publishing date	2019-01-07
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Bio‐optical properties of Arctic drift ice and surface waters north of Svalbard from winter to spring

Kowalczuk, Piotr / Meler, Justyna / Kauko, Hanna M. / Pavlov, Alexey K. / Zabłocka, Monika / Peeken, Ilka / Dybwad, Christine / Castellani, Giulia / Granskog, Mats A.

Journal of geophysical research. 2017 June, v. 122, no. 6

2017

Abstract: We have quantified absorption by CDOM, aCDOM(λ), particulate matter, aₚ(λ), algal pigments, aₚₕ(λ), and detrital material, aNAP(λ), coincident with chlorophyll a in sea ice and surface waters in winter and spring 2015 in the Arctic Ocean north of ... ...

Abstract	We have quantified absorption by CDOM, aCDOM(λ), particulate matter, aₚ(λ), algal pigments, aₚₕ(λ), and detrital material, aNAP(λ), coincident with chlorophyll a in sea ice and surface waters in winter and spring 2015 in the Arctic Ocean north of Svalbard. The aCDOM(λ) was low in contrast to other regions of the Arctic Ocean, while aₚ(λ) has the largest contribution to absorption variability in sea ice and surface waters. aₚ(443) was 1.4–2.8 times and 1.3–1.8 times higher than aCDOM(443) in surface water and sea ice, respectively. aₚₕ(λ) contributed 90% and 81% to aₚ(λ), in open leads and under‐ice waters column, and much less (53%–74%) in sea ice, respectively. Both aCDOM(λ) and aₚ(λ) followed closely the vertical distribution of chlorophyll a in sea ice and the water column. We observed a tenfold increase of the chlorophyll a concentration and nearly twofold increase in absorption at 443 nm in sea ice from winter to spring. The aCDOM(λ) dominated the absorption budget in the UV both in sea ice and surface waters. In the visible range, absorption was dominated by aₚₕ(λ), which contributed more than 50% and aCDOM(λ), which contributed 43% to total absorption in water column. Detrital absorption contributed significantly (33%) only in surface ice layer. Algae dynamics explained more than 90% variability in aₚ(λ) and aₚₕ(λ) in water column, but less than 70% in the sea ice. This study presents detailed absorption budget that is relevant for modeling of radiative transfer and primary production.
Keywords	absorption ; algae ; chlorophyll ; geophysics ; particulates ; primary productivity ; radiative transfer ; research ; sea ice ; spatial distribution ; surface water ; winter ; Arctic Ocean ; Arctic region ; Norway
Language	English
Dates of publication	2017-06
Size	p. 4634-4660.
Publishing place	John Wiley & Sons, Ltd
Document type	Article
Note	JOURNAL ARTICLE
ZDB-ID	161667-5
ISSN	2169-9291 ; 2169-9275 ; 0148-0227 ; 0196-2256
ISSN (online)	2169-9291
ISSN	2169-9275 ; 0148-0227 ; 0196-2256
DOI	10.1002/2016JC012589
Database	NAL-Catalogue (AGRICOLA)

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Article: Composition of dissolved organic matter along an Atlantic Meridional Transect from fluorescence spectroscopy and Parallel Factor Analysis

Kowalczuk, Piotr / Tilstone, Gavin H / Zabłocka, Monika / Röttgers, Rüdiger / Thomas, Rob

Marine chemistry. 2013 Dec. 20, v. 157

2013

Abstract: Absorption spectra and induced fluorescence excitation emission matrices of colored dissolved organic matter were measured in water samples collected along the Atlantic Meridional Transect in different bio-geographic provinces of the Atlantic Ocean from ... ...

Abstract	Absorption spectra and induced fluorescence excitation emission matrices of colored dissolved organic matter were measured in water samples collected along the Atlantic Meridional Transect in different bio-geographic provinces of the Atlantic Ocean from October to November 2010. The highest values of CDOM absorption coefficient at 305nm (aCDOM(305)), were recorded at the continental margins of the English Channel and Patagonian Shelf. The lowest values of aCDOM(305) were observed in the mixed layer of both North and South Atlantic subtropical oligotrophic gyres. The DOM composition was assessed using fluorescence spectroscopy, Excitation Emission Matrix spectra (EEMs) and the Parallel Factor Analysis (PARAFAC) model in addition to spectral indices calculated from CDOM absorption spectrum and EEMs. Six different components were identified in the EEMs by PARAFAC: Two components were similar to the humic-like fraction of DOM, associated with basin scale microbial mineralization processes. These components represent allochthonous DOM in the biogeographic provinces studied. One component of marine humic-like material of autochthonous origin was associated with DOM production from marine phytoplankton. Three components were associated with protein-like DOM. Two protein-like components had the spectral characteristics of pure tryptophan and tyrosine. There was a significant difference in DOM composition both between bio-geographical provinces and above and below the mixed layer. In the mixed layer in all provinces, except the waters of the Western European Shelf, the DOM was dominated by protein-like components. At the Western European Shelf, it was dominated by humic-like components. Fluorescence intensities of humic-like components were high at the Patagonian Shelf, but were up to 40% lower compared to northern hemisphere shelf waters. Humic-like components made a significant contribution to the DOM composition of the upper mesopelagic layer in all provinces, with the highest values at the Equatorial Upwelling Zone. There was a significant inverse relationship between humic-like components and salinity and temperature and a positive relationship with Apparent Oxygen Utilization. The humification index (HIX) was linearly correlated with the intensity of the humic-like DOM components. These trends suggest that the humic-like components are in dynamic equilibrium between likely microbial production in the deep ocean and photochemical degradation in the mixed layer.
Keywords	absorption ; basins ; color ; dissolved organic matter ; factor analysis ; fluorescence ; fluorescence emission spectroscopy ; humification ; mineralization ; models ; oxygen ; phytoplankton ; salinity ; spectral analysis ; temperature ; tryptophan ; tyrosine ; Atlantic Ocean ; English Channel
Language	English
Dates of publication	2013-1220
Size	p. 170-184.
Publishing place	Elsevier B.V.
Document type	Article
ISSN	0304-4203
DOI	10.1016/j.marchem.2013.10.004
Database	NAL-Catalogue (AGRICOLA)

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