Basin scale distribution of chromophoric dissolved organic matter in the Pacific Ocean

Yamashita, Youhei; Tanoue, Eiichiro

doi:10.4319/lo.2009.54.2.0598

Cited by 83 publications

(51 citation statements)

References 38 publications

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“…The larger standard deviations reported in the deeper samples between both Fe and Cu speciation results may also reflect aspects of the quality of the ligand pools present for these elements-such as fresher, biologically produced ligands in the chlorophyll maximum and a "ligand soup" of various organic breakdown materials at depth (Hirose 2007;Hunter and Boyd 2007). This ligand soup at depth in the North Pacific may also include humic-like substances (Laglera and van den Berg 2009;Yamashita and Tanoue 2009). Labs E and F employed the same experimental approach and instrumentation for Cu speciation measurements.…”

Section: Cu Speciationmentioning

confidence: 99%

The organic complexation of iron and copper: an intercomparison of competitive ligand exchange‐adsorptive cathodic stripping voltammetry (CLE‐ACSV) techniques

Buck

Moffett

Barbeau

et al. 2012

Limnology & Ocean Methods

108

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Competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV) is used in chemical oceanography to measure the organic complexation of metal ions in seawater. The bioactive trace metals iron, copper, cobalt, nickel, and zinc are all complexed (up to > 99% of iron and copper) by organic ligands in seawater (van den Berg and Nimmo 1987;Coale and Bruland 1988;Bruland 1989;Gledhill and van den Berg 1994;Rue and Bruland 1995;Wu and Luther 1995;Ellwood and van den Berg 2001), which can control solubility and bioavailability of these elements. Measuring the organic complexation of trace metals is, thus, an exceedingly important component of their biogeochemistry. To date, CLE-ACSV is the only widely accepted technique employed for measuring dissolved metalbinding ligand concentrations ([L i ]) in seawater and the conditional stability constants ( ) for their complexes with the metal of interest (M).To accomplish this, CLE-ACSV employs a well-characterized added ligand (AL) to compete against ambient ligands for M over a complete titration of a buffered seawater sample with additions of inorganic metal (M¢; typically from + 0 to + 10 ¥ [M]). Following equilibrium first with the metal additions (typically several hours) and then with the added ligand (minutes to hours), the resulting M(AL) x complex for each titration point is adsorbed to the surface of a hanging mercury drop electrode (HMDE) at a set voltage potential over a deposition time prede- AbstractCharacterization of the speciation of iron and copper is an important objective of the GEOTRACES Science Plan. To incorporate speciation measurements into such a multinational program, standard practices must be adopted that allow data from multiple labs to be synthesized. Competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV) is the primary technique employed for measuring metal-binding ligands and determining metal speciation in seawater. The determination of concentrations and conditional stability constants of metal-binding ligands is particularly challenging, as results can be influenced both by experimental conditions and interpretation of titration data. Here, we report an investigation between four laboratories to study the speciation of iron and copper using CLE-ACSV. Samples were collected on the GEOTRACES II intercomparison cruise in the North Pacific Ocean in May 2009 at 30° N, 140° W. This intercomparison was carried out shipboard and included an assessment of the viability of sample preservation by freezing. Results showed that consensus values could be obtained between different labs, but that some existing practices were problematic and require further attention in future work. A series of recommendations emerged from this study that will be useful in implementing multi-investigator programs like GEOTRACES.

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Section: Cu Speciationmentioning

confidence: 99%

The organic complexation of iron and copper: an intercomparison of competitive ligand exchange‐adsorptive cathodic stripping voltammetry (CLE‐ACSV) techniques

Buck

Moffett

Barbeau

et al. 2012

Limnology & Ocean Methods

108

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“…In addition, S 275−295 was successfully used as a retrieval method of DOC concentration and as a tracer of terrestrial DOC in river-influenced ocean margin Benner, 2011, 2012;Fichot et al, 2013). Since S 275−295 can be measured with high precision due to relatively high absorbance levels in this wavelength range (Helms et al, 2008), these spectral parameters may also be used as a tracer of water masses and biogeochemical history of CDOM in the open ocean where CDOM levels are quite low (Nelson et al, 2007(Nelson et al, , 2010Swan et al, 2009;Yamashita and Tanoue, 2009). Although changes in S R and S 275−295 along with photobleaching of deep ocean DOM have recently been reported (Stubbins et al, 2012;Helms et al, 2013), the distribution of these parameters has not been evaluated in the open ocean thus far.…”

Section: Introductionmentioning

confidence: 99%

“…Chromophoric dissolved organic matter (CDOM) ubiquitously occurs in the open ocean (Kitidis et al, 2006;Nelson et al, 2007Nelson et al, , 2010Swan et al, 2009;Yamashita and Tanoue, 2009). CDOM is one of the major factors controlling optical properties of seawater Nelson and Siegel, 2013), and thus, controls the light penetration, especially, in the UV region (Fichot et al, 2008;Nelson and Siegel, 2013), which affects the primary production and microbial production, and also the structure of the marine food web (Smith et al, 1992;Herndl et al, 1993;Häder et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

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Photobleaching as a factor controlling spectral characteristics of chromophoric dissolved organic matter in open ocean

et al. 2013

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Abstract. Chromophoric dissolved organic matter (CDOM) ubiquitously occurs in marine environments and plays a significant role in the marine biogeochemical cycles. Basin scale distributions of CDOM have recently been surveyed in the global ocean and indicate that quantity and quality of oceanic CDOM are mainly controlled by in situ production and photobleaching. However, factors controlling the spectral parameters of CDOM in the UV region, i.e., spectral slope of CDOM determined at 275-295 nm (S 275−295 ) and the ratio of two spectral slope parameters (S R ); the ratio of S 275−295 to S 350−400 , have not been well documented. To evaluate the factor controlling the spectral characteristics of CDOM in the UV region in the open ocean, we determined the quantitative and qualitative characteristics of CDOM in the subarctic and subtropical surface waters (5-300 m) of the western North Pacific. Absorption coefficients at 320 nm in the subarctic region were higher than those in the subtropical region throughout surface waters, suggesting that magnitudes of photobleaching were different between the two regions. The values of S 275−295 and S R were also higher in the subtropical region than the subarctic region. The dark microbial incubation showed biodegradation of DOM little affected S 275−295 , but slightly decreased S R . On the other hand, increases in S 275−295 and relative stableness of S R were observed during photo-irradiation incubations respectively. These experimental results indicated that photobleaching of CDOM mainly induced qualitative differences in CDOM at UV region between the subarctic and subtropical surface waters. The results of this study imply that S 275−295 can be used as a tracer of photochemical history of CDOM in the open ocean.

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“…Fluorescence dissolved organic matter (FDOM) is a fraction of chromophoric DOM (CDOM) which not only absorbs but also emits a blue fluorescence when it is irradiated with ultraviolet (UV) light (Coble, 2007). FDOM is often used as an indicator for humic-like marine DOM (Yamashita and Tanoue, 2009) and frequently enriched in the SML (Zhang and Yang, 2013) due to its hydrophobic properties.…”

Section: Introductionmentioning

confidence: 99%

High-resolution variability of the enrichment of fluorescence dissolved organic matter in the sea surface microlayer of an upwelling region

Mustaffa¹,

Ribas-Ribas²,

Wurl³

2017

Elementa: Science of the Anthropocene

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Mustaffa, NIH, et al 2017 High-resolution variability of the enrichment of fluorescence dissolved organic matter in the sea surface microlayer of an upwelling region. Elem Sci Anth, 5: 52, DOI: https://doi.org/10.1525/elementa.242 IntroductionThe uppermost part of the ocean, covering approximately 70% of the surface is defined as the sea surface microlayer (SML) (Liss and Duce, 2005). Due to its unique position between the atmosphere and ocean, the SML plays an important role in biogeochemical processes, including the marine carbon cycle, photochemistry and air-sea exchange of climate-relevant gases. All materials exchanged between the ocean and atmosphere, including gases, particulate organic matter, and sea salt, have to pass through the SML (Liss and Duce, 2005). With a total thickness between 1 µm and 1000 µm, depending on the sampling technique (Shinki et al., 2012) and region of interest (Hardy, 1982), the SML remains sufficiently stable at a global average wind speed of 6.6 m s -1 (Wurl et al., 2011b) to control the rate of air-sea exchange of gases and heat, highlighting its global relevance. It is well established that the SML has unique physical, chemical, and biological properties that differ from those of the wellmixed underlying water masses (Hardy, 1982;Cunliffe et al., 2013). Biological and physical processes in the water column, such as primary productivity, diffusion, buoyancy flux, and rising bubbles, are the main factors determining the enrichment of chemical compounds and microbes in the SML (Wurl et al., 2009;Stolle et al., 2010). Enriched materials include surface-active dissolved organic matter (DOM) (e.g., carbohydrates, proteins and lipids) and particulate organic matter (POM), as well as autotrophic and heterotrophic cells (Williams et al., 1986;Cunliffe et al., 2009). Fluorescence dissolved organic matter (FDOM) is a fraction of chromophoric DOM (CDOM) which not only absorbs but also emits a blue fluorescence when it is irradiated with ultraviolet (UV) light (Coble, 2007). FDOM is often used as an indicator for humic-like marine DOM (Yamashita and Tanoue, 2009) and frequently enriched in the SML (Zhang and Yang, 2013) due to its hydrophobic properties.CDOM enrichment in the SML is of particular interest due to its active role in photochemistry (de Bruyn et al., 2011), as the SML is the part of the ocean with the highest exposure to radiation. For this reason, some photochemical reactions in the SML can be unique (Carlson, 1993), and the SML may act as microreactor (Blough, 2005), including changing the composition of surface active species RESEARCH ARTICLEHigh-resolution variability of the enrichment of fluorescence dissolved organic matter in the sea surface microlayer of an upwelling region Nur Ili Hamizah Mustaffa, Mariana Ribas-Ribas and Oliver Wurl Enrichment of fluorescence dissolved organic matter (FDOM) in the sea surface microlayer (SML) provides insights into biogeochemical processes occurring at the sea surface, including cycling of organic matter, photochemistry, and air-se...

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Basin scale distribution of chromophoric dissolved organic matter in the Pacific Ocean

Cited by 83 publications

References 38 publications

The organic complexation of iron and copper: an intercomparison of competitive ligand exchange‐adsorptive cathodic stripping voltammetry (CLE‐ACSV) techniques

The organic complexation of iron and copper: an intercomparison of competitive ligand exchange‐adsorptive cathodic stripping voltammetry (CLE‐ACSV) techniques

Photobleaching as a factor controlling spectral characteristics of chromophoric dissolved organic matter in open ocean

High-resolution variability of the enrichment of fluorescence dissolved organic matter in the sea surface microlayer of an upwelling region

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