Chromatographic Determination of Nanomolar Cyanate Concentrations in Estuarine and Sea  Waters by Precolumn Fluorescence Derivatization

Widner, Brittany; Mulholland, Margaret R.; Mopper, Kenneth

doi:10.1021/ac400351c

Cited by 38 publications

(41 citation statements)

References 33 publications

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“…For example, while ammonium is frequently at the limit of analytical detection in surface waters, as was observed in this and other studies, it typically accounts for a large fraction of total N uptake because its production and consumption are tightly coupled (Bronk and Steinberg ; Mulholland and Lomas ). Cyanate concentrations were 1–2 orders of magnitude lower in coastal waters in the mid‐Atlantic than those previously observed from the Chesapeake Bay estuary (17–100 nM; Widner et al , unpubl.) and higher on the continental shelf than on the slope (Table ; Fig.…”

Section: Discussionmentioning

confidence: 54%

“…However, marine cyanate concentrations had never been measured prior to the first three cruises, due to the lack of a cyanate assay for seawater, so we based our cyanate additions on those we used for ammonium, nitrite, nitrate, and urea uptake experiments (100 nM final concentration; Mulholland et al unpubl.). Prior to the August 2012 cruise, we made the first measurements of cyanate along a Chesapeake Bay mouth transect and found that cyanate concentrations there ranged from 27.3 nM to 41.1 nM (Widner et al ). Consequently, on the final cruise, tracer additions were decreased to 30 nM to minimize potential over‐estimation of rates while ensuring sufficient tracer to detect enrichment in the particulate phase and minimize depletion of the source pool over the course of the incubation (Lipschultz ).…”

Section: Methodsmentioning

confidence: 99%

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Cyanate distribution and uptake in North Atlantic coastal waters

Widner

Mulholland

2017

Limnology & Oceanography

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Cyanate (OCN−) is a reduced nitrogen compound that may be a source of nitrogen and carbon for marine phytoplankton. Cyanate is produced photochemically and through organic matter degradation but its distribution in marine systems is poorly defined because, until recently, there was no method to measure its concentration in marine environments. Here, we report results from the first regional oceanographic survey of cyanate distributions and uptake. Cyanate concentrations ranged from below detection (0.4 nM) to 11 nM in the coastal North Atlantic Ocean along the North American continental shelf and were slightly higher in nearshore surface waters than offshore surface waters. Subsurface cyanate maxima were observed at many stations suggesting a nonconservative distribution. Subsurface cyanate peak concentrations were tightly correlated with chlorophyll a concentrations integrated throughout the water column (R2 = 0.79). Cyanate N and C uptake were measurable in all regions and seasons sampled. Cyanate N uptake was significantly higher than cyanate C uptake for all cruises (1.3 ± 1.9 nmol L−1 h−1 and 0.4 ± 0.6 nmol L−1 h−1 for N and C, respectively). However, cyanate N uptake was significantly lower in November than in June and August, and cyanate C uptake was significantly higher in November than during June and August. Spatial trends in cyanate distribution and uptake, along with the correlation between depth‐integrated Chl a concentrations and cyanate maxima, suggest that cyanate is taken up in the euphotic zone and is likely produced by degradation of phytoplankton‐derived organic matter in subsurface waters.

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Section: Discussionmentioning

confidence: 54%

Section: Methodsmentioning

confidence: 99%

Cyanate distribution and uptake in North Atlantic coastal waters

Widner

Mulholland

2017

Limnology & Oceanography

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“…Limits of detection for

{NO}_{3}^{-}

{NO}_{2}^{-}

{NH}_{4}^{+}

, and urea were 70 nM, 20 nM, 40 nM, and 80 nM, respectively, using the nutrient autoanalyzers, and the limit of detection for

{NH}_{4}^{+}

using the OPA method was 10 nM. The limit of detection for cyanate was 0.4 nM (Widner et al ).…”

Section: Methodsmentioning

confidence: 99%

Cyanate distribution and uptake above and within the Eastern Tropical South Pacific oxygen deficient zone

Widner

Mordy

Mulholland

2017

Limnology & Oceanography

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Cyanate is a simple reduced nitrogen (N) compound that can be a source of N and carbon (C) for marine organisms and may also be a substrate for dissimilatory N processes such as nitrification and anammox. We measured cyanate distributions and cyanate and urea uptake in the Eastern Tropical South Pacific, a region defined by coastal upwelling, high primary productivity, a shallow oxic layer, and rapid N loss from a large oxygen deficient zone (ODZ). Cyanate concentrations ranged from below the limit of detection (0.4 nM) to 45 nM in the oxic upper water column. Below the oxycline, cyanate concentrations were largely below detection except for small cyanate peaks (2–8.3 nM) within the core of the ODZ at some stations. The majority of N taken up in the shallow oxic layer was from ammonium and urea (78% ± 8%); cyanate uptake was < 2% of these. Uptake of cyanate fluctuated diurnally with the highest rates of cyanate N uptake in the early afternoon. In the ODZ, rates of cyanate, urea, and ammonium uptake were similar to each other (0.1–14 nmol N L−1 d−1) and to previously reported rates of 29N2 production supported by cyanate and ammonium (3–14 nmol N2 L−1 d−1). This suggests a role for cyanate in the metabolism of anaerobic microbes and a potential role for cyanate in the anammox reaction (cyanammox). To our knowledge, these represent the first rates of N uptake in a marine anoxic water column.

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“…Cyanate could result from equilibrium with intracellular urea or carbamoyl phosphate decomposition, and is a toxic N-containing compound existing in the ocean (Widner et al, 2013). The assembled unigene of cynS contained DinoSL at 5 0 end and almost complete coding region, indicating that it was dinoflagellate originated and was likely functional.…”

Section: N Uptake and Assimilationmentioning

confidence: 99%