Samplers, Niskin

Numbers result from common computer analyses and not all such figures will be necessarily significant PCS = Plastic-coated steel hydrowire SS = Stainless steel (type 302 unlubricated) hydrowire KEV = Kevlar hydrowire HB = Hydro-bios sampler MGF = Modified GO-FLO sampler Mod GF = Unmodified GO-FLO sampler Exw GF = Unmodified GO-FLO sampler NIS = Modified Niskin sampler m = mean sd = standard deviation... 

The results in Fig. 1.2 show values between 0.06 and 0.12nmol/kg. The average mercury contents obtained by pumping, Niskin sampler, Go-Flo sampler, and the close-open-close device are 0.09 0.01,0.08 0.03, and 0.10 0.02 nmol/kg, respectively. 

Williams, P. J., and Robertson, J. I. (1989). A serious inhibition problem from a Niskin sampler during plankton productivity studies. Limnol. Oceanogr. 34, 1300—1305. 

A Comparison of Various Niskin Samplers and a Pumping System... 

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... 

Comparison of commercially available rosette samplers (Table 1-2, Fig. 1-5) shows that different constructions follow almost the same principle. A circular protective frame accommodates 3-36 samplers which commonly can be used as serial samplers in hydrocasts. In addition to their usage in basic hydrochemical studies, standard rosette samplers (e.g., 12 L Niskin samplers see Table 1-2) are also suitable for the collection of oceanographic tracers such as fluorocarbon compounds, helium-3, tritium or even carbon-14 (except for studies in the deep waters of the Pacific and Indian Oceans, where large special samplers of > 250 L volume are needed see Table 1-2 and Oiapter 13). 

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... 

In light of the above data, use of the pump system was discontinued, and a Niskin Rosette sampler (Figure 3) was used to perform a com-... 

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. 

Pump collection Bottle (e.g., Niskin) Biological net sampler In situ plate collection Porous cup (in soils) (Tension-free) Lysimeter (in soils)... 

Niskin 1010 PVC tube. Teflon coating optional, internal rubber spring, for single use and in rosette-type samplers, reduced flushing 1.2-30 2-12.7 ul Std., (TM) GO... 

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. 

Plastic samplers are cleaned internally in a manner similar to that described for plastic bottles. Go-Flo samplers (Niskin type see Qiapter 1) are first thoroughly cleaned with a detergent, then rinsed with tap water and, after soaking in about 1 mol/L HQ (a.g.) for several days, flushed with a final rinse of purest distilled water. Afterwards, the samplers are wrapped in clean plastic bags for storage. 

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). 

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