Simultaneous determination of dissolved organic carbon and total dissolved nitrogen in seawater by high temperature catalytic oxidation: conditions for precise shipboard measurements

Álvarez‐Salgado, Xosé Antón; Miller, Axel E. J.

doi:10.1016/s0304-4203(98)00037-1

Cited by 167 publications

(60 citation statements)

References 23 publications

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“…The value agreed with the system blank reported in other previous studies (Álvarez-Salgado and Miller, 1998;Badr et al, 2003;Benner and Strom, 1993;Hopkinson et al, 1993;Koike and Tupas, 1993;Suzuki et al, 1992). The blank correction was applied to DOC and TDN data.…”

supporting

confidence: 92%

Distribution and C / N stoichiometry of dissolved organic matter in the North Sea in summer 2011–12

Chaichana

Jickells

Johnson

2017

Preprint

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Abstract. We present the distribution and C:N stoichiometry of dissolved organic matter (DOM) in the North Sea in 2 summers (August 2011 and August 2012), with supporting data from the intervening winter (January 2012). This data demonstrates local variability superimposed on a general pattern of decreasing DOM with increasing salinity, suggesting 10 strong control over broad scale concentrations by mixing between riverine sources and the open North Atlantic. We observe differences in DOC and DON concentrations and gradients between the two summers, leading to an estimated 10-20 Tg difference in the DOM carbon inventory between the 2 years, which is of the same order as the annual uptake of atmospheric CO 2 by the North Sea system, and thus significant for the carbon budget of the North Sea. Differences were particularly pronounced in the bottom layer of the seasonally stratifying Northern North Sea, with higher DOC and lower DON in 2011 15 and lower C:N ratio and more moderate concentrations of DOC and DON in 2012. Using other data we consider the extent to which these differences in the concentrations and C:N ratio of DOM could be due to differences in the biogeochemistry or physical circulation in the 2 years, or a combination of both. We discuss the implications of these observations for the shelf sea carbon pump and the export of carbon rich organic matter off the shelf. 20

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supporting

confidence: 92%

Distribution and C / N stoichiometry of dissolved organic matter in the North Sea in summer 2011–12

Chaichana

Jickells

Johnson

2017

Preprint

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Section: Fluorescence Of Particulate and Dissolved Organic Matter (Dom)mentioning

confidence: 99%

“…The catalyser was 0.5% Pt on Al 2 O 3 balls. The DOC concentration of each sample was obtained by subtracting the average (± SD) peak area of 3 to 5 injections (150 µl) from the average (± SD) peak area of the freshly produced Milli-Q water used as a blank and dividing by the slope of the standard curve with potassium hydrogen phthalate (Álvarez-Salgado & Miller 1998).Aliquots for the quantification of FDOM were collected directly in a quartz cell of 1 cm path-length and measured in a Perkin Elmer LS 55 luminiscence spectrometer. The fluorescence of particulate or ganic matter (FPOM) was obtained by subtracting the FDOM from the fluorescence of the unfiltered sample.…”

mentioning

confidence: 99%

Response of two marine bacterial isolates to high CO<sub>2 concentration

Teira¹,

Fernández²,

Álvarez‐Salgado³

et al. 2012

Mar. Ecol. Prog. Ser.

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Experimental results related to the effects of ocean acidification on planktonic marine microbes are still rather inconsistent and occasionally contradictory. Moreover, laboratory or field experiments that address the effects of changes in CO 2 concentrations on heterotrophic microbes are very scarce, despite the major role of these organisms in the marine carbon cycle. We tested the direct effect of an elevated CO 2 concentration (1000 ppmv) on the biomass and metabolic rates (leucine incorporation, CO 2 fixation and respiration) of 2 isolates belonging to 2 relevant marine bacterial families, Rhodobacteraceae (strain MED165) and Flavobacteriaceae (strain MED217). Our results demonstrate that, contrary to some expectations, high p CO 2 did not negatively affect bacterial growth but increased growth efficiency in the case of MED217. The elevated partial pressure of CO 2 (pCO 2 ) caused, in both cases, higher rates of CO 2 fixation in the dissolved fraction and, in the case of MED217, lower respiration rates. Both responses would tend to increase the pH of seawater acting as a negative feedback between elevated atmospheric CO 2 concentrations and ocean acidification. KEY WORDS: Bacterial metabolism · Flavobacteriaceae · Ocean acidification · RhodobacteraceaeResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 453: 27-36, 2012 on marine bacterial isolates (Takeuchi et al. 1997, Labare et al. 2010. The latter studies found a decrease in the production and growth rates at pH < 7 -values far from the usual pH observed in ocean waters under present or future scenarios of elevated p CO 2 .Most microorganisms, particularly heterotrophic bacteria, are able to assimilate CO 2 as part of their metabolism through anaplerotic reactions (Roslev et al. 2004). Although light-independent or dark CO 2 assimilation has been usually assumed to be insignificant in oxygenated marine waters, a recent work by Alonso-Sáez et al. (2010) suggests that the global relevance of this process could have been underestimated. Those results show for the first time that high ambient CO 2 concentrations could stimulate CO 2 fixation rates by increasing the CO 2 flux into the cells.A comprehensive understanding of the effect of elevated CO 2 concentration on carbon cycling in the ocean requires the analysis of both production and respiration rates to provide a total carbon budget. However, to the best of our knowledge none of the published studies have simultaneously addressed the effect of CO 2 on BP and respiration, which are essential variables for bacterial growth efficiency (BGE) calculations. Allgaier et al. (2008) did find changes in bacterial taxonomic composition in response to high CO 2 concentrations, which suggest that the effects of elevated p CO 2 are likely to vary among species. Therefore, the aim of the present study was to test the direct effect of elevated CO 2 concentrations (1000 ppmv) on the biomass and metabolic rates (leucine incorporation, CO 2 fixation and respiration...

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“…were measured with a nitrogen-specific Antek 7020 nitric oxide chemiluminescence detector coupled in series with the carbon-specific Infra-red Gas Analyser of a Shimadzu TOC-5000 organic carbon analyzer, as described in Álvarez-Salgado and Miller (1998) with a precision of ±0.7 µmol C l -1 and ±0.2 µmol N l -1 .…”

Section: Salinity (S)mentioning

confidence: 99%