Sampling Niskin samplers

Syiplinq, Discrete water column samples were obtained with 5-L Niskin bottles attached to a General Oceanics Rosette fitted with Plessey Environmental Systems model 9040 CTD. A 1-L aliquot of seawater was transferred from the Niskin samplers into glass-stoppered bottles in such a way that air bubbles were not trapped. The bottles were then stored in the dark at... 

Fig. 1-11. Niskin sampler for the collection of microbiological samples from deep ocean waters (General Oceanics).

At the sampling step, contamination from sampling bottles and hydrowire should be minimized [10], Old types of sampling devices such as Nansen and Knudsen are constructed mostly from brass, which may cause contamination of Cu and Zn into seawater. The recently developed Niskin plastic sampling bottle provides less contamination from the sampler walls. However, the materials used for the end-caps or springs, rubber or Teflon-coated stainless steel, sometimes release significant amounts of Ba, Cu, Sb and Zn [14]. 

Upon acquisition of the Inter-Ocean pump sampling system, a series of seawater samples was collected from New York Bight at 10 m depth simultaneously with the pump and with Niskin 10-1. samplers with internal rubber closmres. The samples were Altered through 0.4/x Nucleopore filters. One aliquot was frozen for subsequent analysis of nitrate, nitrite, phosphate, and silicate by standard automated techniques. A second aliquot was acidified to pH 1 with siUca-distilled, concentrated nitric acid and was subsequently analyzed by flameless atom reservoir atomic absorption spectrophotometry, both by direct injection (4) and after extraction of the metal pyrollidine dithiocarbamates with methyl isobutyl... 

Collection of samples at various depths with Niskin bottles, extraction of unfiltered small volumes (1 1) with carbon tetrachloride, collection of particulate hydrocarbons using a neuston sampler determination of hydrocarbons by fluorescence spectrophotometry. 

Model lOlOC Niskin-type sampler, special holding device allows single use in vertical and horizontal direction, designed for surface sampling 1.7, 2.5 2.9, 3.6 ul Std. GO... 

Deadweight in air (kg) in parantheses limited suitability intelligent rosette multi-bottle water sampling system small volume sampler FSl SURE-FIRE submersible array Niskin non-metallic convertible surface water sampling bottles. 

Station salinity samples for analysis with a salinometer are taken from water samplers that are closed at desired depths or pressures. In many cases, a rosette sampler is used that carries Niskin or comparable water sampling bottles (see Chapter 1). Ihe bottles are mounted in one or more rings on a frame. Closing the bottles at desired pressure levels is triggered from the deck unit in the ship s laboratory. New s tems allow selection of bottles individually and not just in the order of their position on the frame. Most frequently, and necessary for WOCE standards, the rosette sampler is operated together with a CTD that is mounted on the rosette s frame. The CTD s on-line pressure information is then used for controlled closing of the water samplers. 

Most samplers used for seawater collection are adequate to obtain seawater samples for arsenic species determination we have used Niskin and Go-Flo samplers (General Ocea-nics) as well as TPN and COC samplers (Hydrobios) for sample collection and have not seen evidence of contamination resulting from any of these samplers (see also Chapter 1). 

Water for the analysis of suspended particles may be collected with any clean water sampler used for oceanographic work, e.g., Niskin bottles, Go-Flo bottles, Nansen bottles. Hydrobios water samplers (see also Chapter 1). The sample volume will depend on the expected concentration of POM. In nearshore and/or biologically productive water, 0.5-2 L usually is an adequate sample volume. Ten litres may be required in particle-poor open ocean waters such as the Sargasso Sea. For sampling large volumes of water, 30 L Niskin bottles are recommended. Even larger volumes may be sampled with in situ pumps. (See Chapters 1,2 and 13). 

Bottle samplers (e.g., Niskin, Nansen, Go-Flo, etc.) allow the collection of discrete water samples (0.5-30 L), whereas the acquisition of large volumes (100-1000 L) or a continuous... 

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