A sensitive flow-batch system for on board determination of ultra-trace ammonium in seawater: Method development and shipboard application

Zhu, Yong; Yuan, Dongxing; Huang, Yongming; Ma, Jian; Feng, Sichao

doi:10.1016/j.aca.2013.08.009

Cited by 62 publications

(54 citation statements)

References 27 publications

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“…Simultaneously, continuous profiling sensor measurements of NO 3 ‐ (ISUS, Satlantic) and DO were conducted. Detailed analytical methods are introduced in the supporting information (Bourgault et al, ; Cao & Dai, ; Dai et al, ; Han et al, ; Johnson et al, ; Ma et al, ; Xie et al, ; Zhang, ; Zhou et al, ; Zhu et al, ).…”

Section: Methodsmentioning

confidence: 99%

Diapycnal Fluxes of Nutrients in an Oligotrophic Oceanic Regime: The South China Sea

Liu

Kao

et al. 2017

Geophysical Research Letters

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Nutrients from depth have been hypothesized as a primary source of new nutrients that sustain new productivity in oligotrophic oceans; however, the flux is challenging to quantify. Here we show for a first time in the oligotrophic South China Sea an extremely low diapycnal dissolved inorganic nitrogen (DIN) flux as 1.8 × 10−4 mmol m−2 d−1 in the nutrient‐depleted layer (NDL) above the nutricline, where other nutrient supplies sustain the new production. Here higher phosphate and silicate fluxes relative to DIN than Redfield stoichiometry further indicate N‐limited biological productivity and additional removal of DIN by diatoms. Below the NDL across the nutricline to the base of euphotic zone, termed as nutrient replete layer, the DIN flux is three orders of magnitude larger and sufficient in supporting the export production therein. Here higher DIC flux relative to DIN than Redfield stoichiometry further infers DIC excess in the upper ocean.

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Section: Methodsmentioning

confidence: 99%

Diapycnal Fluxes of Nutrients in an Oligotrophic Oceanic Regime: The South China Sea

Liu

Kao

et al. 2017

Geophysical Research Letters

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“…Artificial seawater, prepared with solid NaCl and MgSO 4 according to a national standard [21], was used as a matrix for salt-effect experiments. Reagent bottles were sealed with air inlet clean-up devices which consisted of a syringe filled with acidic silica gel, as described previously [20,22].…”

Section: Reagentsmentioning

confidence: 99%

Automated determination of nitrate plus nitrite in aqueous samples with flow injection analysis using vanadium (III) chloride as reductant

Shu

Lin

Chen

et al. 2016

Talanta

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“…At present, quantitative estimation of ammonium at low levels is still a huge challenge, in spite of the fact that the problems associated with sample storage and contamination have been resolved (Amornthammarong et al ; Zhu et al ; Hashihama et al ; Kodama et al ). One of the most important setbacks is the availability of ammonium‐free seawater.…”

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confidence: 99%

“…The concentration of ammonium in oceanic waters, particularly in oligotrophic oceans and deep oceans, is typically below 1 lmol L 21 (Watson et al 2005). In the surface seawater of the South China Sea (SCS), ammonium is present in dozens of nanomolar concentrations (Zhu et al 2013). In order to measure such low levels of ammonium in the oceanic waters, different sensitive methods have been developed and applied (Amornthammarong and Zhang 2008;Plant et al 2009;Bey et al 2011;Zhu et al 2014;Hashihama et al 2015;Kodama et al 2015).…”

mentioning

confidence: 99%

“…However, there are several discrepancies in the application of these methods, since they require measurements of nanomolar concentrations of ammonium (Plant et al 2009). At present, quantitative estimation of ammonium at low levels is still a huge challenge, in spite of the fact that the problems associated with sample storage and contamination have been resolved (Amornthammarong et al 2006;Zhu et al 2013;Hashihama et al 2015;Kodama et al 2015). One of the most important setbacks is the availability of ammonium-free seawater.…”

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confidence: 99%

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A novel ammonium‐free seawater preparation method for determination of trace quantities of ammonium in seawater

Zhu

Yuan

Chen

et al. 2017

Limnology & Ocean Methods

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A novel method for preparation of ammonium-free seawater, which is used as a carrier solution and matrix for standard solutions, was designed. These standard solutions are used for calibration curve in flow analysis to detect trace quantities of ammonium in seawater. The system, which consisted of only a peristaltic pump and a hydrophilic-lipophilic balance (HLB) cartridge, was simple, convenient, and easy to operate. The original seawater used in the method could be collected from the coastal regions. And appropriate quantities of ophthaldialdehyde (OPA) and sulfite solution were added to the original seawater (The molar proportions of ammonium : OPA : sulfite were 1 : 200 : 80). After allowing it to set for more than 16 h, the seawater was pumped through the HLB cartridge. The reaction product of ammonium (present in the matrix), OPA and sulfite was retained by the HLB column and the solution coming out of the cartridge was ammonium-free seawater. The ammonium in the original seawater was efficiently removed and also its concentration in the ammonium-free seawater prepared by this method was much lower than that of the seawater collected from the surface of the South China Sea. The difference in the salinity of the seawater before and after the process was negligible, and also the pH was slightly increased. Moreover, ammonium-free seawater could be prepared whenever required, and contamination due to transportation and storage could be prevented.

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A sensitive flow-batch system for on board determination of ultra-trace ammonium in seawater: Method development and shipboard application

Cited by 62 publications

References 27 publications

Diapycnal Fluxes of Nutrients in an Oligotrophic Oceanic Regime: The South China Sea

Diapycnal Fluxes of Nutrients in an Oligotrophic Oceanic Regime: The South China Sea

Automated determination of nitrate plus nitrite in aqueous samples with flow injection analysis using vanadium (III) chloride as reductant

A novel ammonium‐free seawater preparation method for determination of trace quantities of ammonium in seawater

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