Variability of nitrate concentration in nitrogen-depleted subtropical surface waters

Eppley, Richard W.; Garside, C.; Renger, Edward H.; Orellana, E.

doi:10.1007/bf01313241

Cited by 42 publications

(11 citation statements)

References 25 publications

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“…NO,-concentration was determined at the beginning and end of the incubations as before. In situ changes in N03-concentration were <20 nM between morning and evening samples from the upper 20 m, indicating NO,-consumption during the day that agreed well with the incubation results (Eppley et al 1990). Sixteen daytime and four overnight experiments yielded successful depth profiles of net changes in N03-concentration.…”

Section: Acknowledgmentssupporting

confidence: 74%

“…4). Other examples of apparent nitrification during this cruise were reported earlier (Eppley et al 1990). …”

Section: Acknowledgmentsmentioning

confidence: 93%

“…In this study the N03-utilization rate per unit of volume was a linear function of NO,-concentration for concentrations below about 40 nM in both areas I and 2 (Eppley et al 1990) and this relation accounted for most of the variability in NO,-use in the upper euphotic zone where NO,-concentrations were low. The depth-integrated rates of NO,-use also increased with the NO,-content of the euphotic zone in area 1 (Fig.…”

Section: Acknowledgmentsmentioning

confidence: 95%

“…Sources of error in the chemiluminescence NO,-measurements were examined in detail earlier (Eppley et al 1990) and will not be repeated here. That report considered contamination problems and their avoidance, interfering substances, nitrification, and comparisons of NO,-changes in situ with the bottle incubations.…”

Section: Acknowledgmentsmentioning

confidence: 99%

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Nitrate use by plankton in the eastern subtropical North Atlantic, March‐April 1989

Eppley

Koeve

1990

Limnology & Oceanography

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Nitrate concentration was measured in seawater samples from the euphotic zone at the beginning and end of 12‐h, daytime, in situ incubations. The changes in concentration are considered to be measurements of new production. During periods of 2–3 weeks in March–April 1989, important time scales for NO3− input to the euphotic zone (i.e. residence times) and new production were ~26 d at 18°N, 31°W and ~10 d near 33°N, 21°W. The average rate of NO3− use in the two areas was 2.63 and 0.62 mmol N m−2 (12 h)−1, or, in carbon equivalents 209 and 49 mg C m−2 d−1, respectively. These values bracket the large‐scale estimate by Jenkins of new production in the nearby beta triangle of 150 mg C m−2 d−1.

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Section: Acknowledgmentssupporting

confidence: 74%

“…4). Other examples of apparent nitrification during this cruise were reported earlier (Eppley et al 1990). …”

Section: Acknowledgmentsmentioning

confidence: 93%

Section: Acknowledgmentsmentioning

confidence: 95%

Section: Acknowledgmentsmentioning

confidence: 99%

See 2 more Smart Citations

Nitrate use by plankton in the eastern subtropical North Atlantic, March‐April 1989

Eppley

Koeve

1990

Limnology & Oceanography

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“…Since the development of sensitive analytical procedures, it has been shown that nitrate concentrations of subtropical surface waters over much of the world's oceans, including the subtropical gyres, is often at sub-micromolar concentrations (3 to <50 nmoles l −1 ). Using a chemiluminescent method, Garside (1985) and Eppley et al (1990) previously found nitrate concentrations <10 nM in the Sargasso Sea and in the subtropical Pacific. These concentrations, which would be depleted in a few hours by the ambient assemblages of phytoplankton, were low but not zero.…”

Section: Discussionmentioning

confidence: 99%

Distribution of inorganic and organic nutrients in the South Pacific Ocean − evidence for long-term accumulation of organic matter in nitrogen-depleted waters

2008

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Abstract. During the BIOSOPE cruise the RV Atalante was dedicated to study the biogeochemical properties in the South Pacific between the Marquesas Islands (141 • W-8 • S) and the Chilean upwelling (73 • W-34 • S). Over the 8000 km covered by the cruise, several different trophic situations were encountered, in particular strong oligotrophic conditions in the South Pacific Gyre (SPG, between 123 • W and 101 • W). In this isolated region, nitrate was undetectable between the surface and 160-180 m and only trace quantities (<20 nmoles l −1 ) of regenerated nitrogen (nitrite and ammonium) were detected, even in the subsurface maximum. Integrated nitrate over the photic layer, which reached 165 m, was close to zero. Despite this severe nitrogendepletion, phosphate was always present in significant concentrations (≈0.1 µmoles l −1 ), while silicic acid was maintained at low but classical oceanic levels (≈1 µmoles l −1 ). In contrast, the Marquesas region (MAR) to the west and Chilean upwelling (UPW) to the east were characterized by high nutrient concentrations, one hundred to one thousand fold higher than in the SPG. The distribution of surface chlorophyll reflected the nitrate gradient, the lowest concentrations (0.023 nmoles l −1 ) being measured at the centre of the SPG, where integrated value throughout the photic layer was very low (≈ 10 mg m −2 ). However, due to the relatively high concentrations of chlorophyll-a encountered in the DCM (0.2 µg l −1 ), chlorophyll-a concentrations throughout the photic layer were less variable than nitrate concentrations (by a factor 2 to 5). In contrast to chlorophyll-a, integrated particulate organic matter (POM) remained more or less constant along the study area (500 mmoles m −2 , 60 mmoles m −2 and 3.5 mmoles m −2 for particulate organic carbon, particulate organic nitrogen and particulate organic phosphorus, Correspondence to: P. Raimbault (patrick.raimbault@univmed.fr) respectively), with the exception of the upwelling, where values were two fold higher. The residence time of particulate carbon in the surface water was only 4-5 days in the upwelling, but up to 30 days in the SPG, where light isotopic δ 15 N signal noted in the suspended POM suggests that N 2 -fixation provides a dominant supply of nitrogen to phytoplankton. The most striking feature was the large accumulation of dissolved organic matter (DOM) in the SPG compared to the surrounding waters, in particular dissolved organic carbon (DOC) where concentrations were at levels rarely measured in oceanic waters (>100 µmoles l −1 ). Due to this large pool of DOM in the SPG photic layer, integrated values followed a converse geographical pattern to that of inorganic nutrients with a large accumulation in the centre of the SPG. Whereas suspended particulate matter in the mixed layer had a C/N ratio largely conforming to the Redfield stochiometry (C/N≈6.6), marked deviations were observed in this excess DOM (C/N≈16 to 23). The marked geographical trend suggests that a net in situ source exists, mainly due to biologic...

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Regionally variable contribution of dissolved organic phosphorus to marine annual net community production

Letscher

Wang

Liang

et al. 2022

Preprint

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Marine dissolved organic phosphorus (DOP) can serve as an organic nutrient to marine autotrophs, helping to sustain a portion of annual net community production (ANCP). Numerical models of ocean circulation and biogeochemistry have diagnosed the magnitude of this process at regional to global scales but have thus far been validated against DOP observations concentrated within the Atlantic basin. Here we assimilate a new marine DOP dataset with global coverage to optimize an inverse model

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Variability of nitrate concentration in nitrogen-depleted subtropical surface waters

Cited by 42 publications

References 25 publications

Nitrate use by plankton in the eastern subtropical North Atlantic, March‐April 1989

Nitrate use by plankton in the eastern subtropical North Atlantic, March‐April 1989

Distribution of inorganic and organic nutrients in the South Pacific Ocean − evidence for long-term accumulation of organic matter in nitrogen-depleted waters

Regionally variable contribution of dissolved organic phosphorus to marine annual net community production

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