Methods of Seawater Analysis

Grasshoff, Klaus; Kremling, Klaus; Ehrhardt, Manfred

doi:10.1002/9783527613984

Cited by 2,268 publications

(144 citation statements)

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“…For Winkler titration measurements, 120 mL BOD glass bottles with glass stopper were used to sample the water using the procedures presented by Grasshoff et al (1983). Briefly, samples were carefully transferred into 120 mL oxygen bottles by using tubing with the tip submerged, allowing 2 volumes of overflow.…”

Section: Wikner Et Almentioning

confidence: 99%

“…A 0.14°C systematic temperature deviation resulted in a closely correlated change in the oxygen concentration of 1.0 µmol dm -3 (R 2 = 0.89, n = 39, 13.6-15.5 h). The slope coefficient of -5.9 µmol dm -3°C-1 matched the expected dependence of oxygen dissolution on temperature as defined in Grasshoff et al (1999) and was therefore associated with the temperature-dependent mathematical algorithms of the sensor. The calculation of the O 2 solubility at standard air mixture and pressure, used in the calculation of relative O 2 saturation in the Optode, involves temperature factors raised to the power of 5 (Garcia and Gordon 1992).…”

Section: Temperature Controlmentioning

confidence: 99%

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Precise continuous measurements of pelagic respiration in coastal waters with Oxygen Optodes

Wikner

Panigrahi

Nydahl

et al. 2013

Limnology & Ocean Methods

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An analytical setup for respiration rate measurements was developed and evaluated in pelagic water samples using a commercially available optical oxygen sensor (Optode™). This setup required the development of a gas tight stopper to connect the sensors to a 1 dm 3 glass sample bottle, precise temperature control (± 0.05°C), and proper stirring of samples. The detection limit and precision of the method was 0.3 mmol O 2 m -3 d -1 . This was similar to the detection limit for the high-precision Winkler titration method reported in field studies. When compared with the Winkler method, the Optode sensor enabled operator-independent, high temporal resolution measurement of respiration, better coverage of plankton groups and detection of non-linear oxygen decline, without the need for wet chemistry. Respiration rates measured by the Optodes showed good accuracy when compared with measurements made with the Winkler titration method (3% deviation), followed the expected temperature response (Q 10 = 3.0), were correlated with chlorophyll a and were congruent with earlier reported values in the literature. The main source of uncertainty was a necessary correction for system drift during the incubation period, due to oxygen release from the plastic components. Additionally, less stringent temperature control on board research vessels during rough seas reduced the precision. We conclude that the developed Optode system can be used to measure respiration in productive coastal waters. Samples from cold or deep waters were, however, often below the detection limit.

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Section: Wikner Et Almentioning

confidence: 99%

Section: Temperature Controlmentioning

confidence: 99%

Precise continuous measurements of pelagic respiration in coastal waters with Oxygen Optodes

Wikner

Panigrahi

Nydahl

et al. 2013

Limnology & Ocean Methods

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“…At each station, water samples were collected using 12-l Niskin bottles on a CTD rosette system equipped with temperature, pressure, conductivity and oxygen sensors. Nutrients and oxygen were determined according to Grasshoff et al (1999).…”

Section: Sampling and Analytical Methodsmentioning

confidence: 99%

An eddy-stimulated hotspot for fixed nitrogen-loss from the Peru oxygen minimum zone

et al. 2012

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Abstract. Fixed nitrogen (N) loss to biogenic N 2 in intense oceanic O 2 minimum zones (OMZ) accounts for a large fraction of the global N sink and is an essential control on the ocean's N-budget. However, major uncertainties exist regarding microbial pathways as well as net impact on the magnitude of N-loss and the ocean's overall N-budget. Here we report the discovery of a N-loss hotspot in the Peru OMZ associated with a coastally trapped mesoscale eddy that is marked by an extreme N-deficit matched by biogenic N 2 production, high NO − 2 levels, and the highest isotope enrichments observed so far in OMZ's for the residual NO − 3 . High sea surface chlorophyll in seaward flowing streamers provides evidence for offshore eddy transport of highly productive, inshore water. Resulting pulses in the downward flux of particles likely stimulated heterotrophic dissimilatory NO − 3 reduction and subsequent production of biogenic N 2 within the OMZ. A shallower biogenic N 2 maximum within the oxycline is likely a feature advected by the eddy streamer from the shelf. Eddy-associated temporal-spatial heterogeneity of N-loss, mediated by a local succession of microbial processes, may explain inconsistencies observed among prior studies. Similar transient enhancements of N-loss likely occur within all other major OMZ's exerting a major influence on global ocean N and N isotope budgets.

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“…Cellular C, N and P of the diatoms in the second grazing experiment were also measured by filtering 10-15 ml of culture onto a pre-combusted GF/F filter, and storing the filters at −80 • C until analysis. Cellular C and N were analyzed with a CHN elemental analyzer (Perkin-Elmer) and cellular P was analyzed as ortho-phosphate after acidic oxidative hydrolysis with 1% HCl (Grasshoff et al, 1999). The cell size of the diatom prey was determined using a Coulter Counter (Beckman Coulter, Z2 Coulter Particle Count and Size Analyzer).…”

Section: Experimental Organisms and Culture Conditionsmentioning

confidence: 99%

“…following the procedures described by Grasshoff et al (1999). Cellular C, N and P of the diatoms in the second grazing experiment were also measured by filtering 10-15 ml of culture onto a pre-combusted GF/F filter, and storing the filters at −80 • C until analysis.…”

Section: Experimental Organisms and Culture Conditionsmentioning

confidence: 99%

Effect of the Silica Content of Diatoms on Protozoan Grazing

Zhang

Liu

et al. 2017

Front. Mar. Sci.

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This study examined the effect that silica content in diatom cells has on the behavior of protists. The diatoms Thalassiosira weissflogii and T. pseudonana were cultured in high or low light conditions to achieve low and high silica contents, respectively. These cells were then fed to a heterotrophic dinoflagellate Noctiluca scintillans and a ciliate Euplotes sp. in single and mixed diet experiments. Our results showed that in general, N. scintillans and Euplotes sp. both preferentially ingested the diatoms with a low silica content rather than those with a high silica content. However, Euplotes sp. seemed to be less influenced by the silica content than was N. scintillans. In the latter case, the clearance and ingestion rate of the low silica diatoms were significantly higher, both in the short (6-h) and long (1-d) duration grazing experiments. Our results also showed that N. scintillans required more time to digest the high silica-containing cells. As the high silica diatoms are harder to digest, this might explain why N. scintillans exhibits a strong preference for the low silica prey. Thus, the presence of high silica diatoms might limit the ability of the dinoflagellate to feed. Our findings suggest that the silica content of diatoms affects their palatability and digestibility and, consequently, the grazing activity and selectivity of protozoan grazers.

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Methods of Seawater Analysis

Cited by 2,268 publications

References 0 publications

Precise continuous measurements of pelagic respiration in coastal waters with Oxygen Optodes

Precise continuous measurements of pelagic respiration in coastal waters with Oxygen Optodes

An eddy-stimulated hotspot for fixed nitrogen-loss from the Peru oxygen minimum zone

Effect of the Silica Content of Diatoms on Protozoan Grazing

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