Go-Flo samplers

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. 

Reliable results on trace elements require precautions to avoid contamination. Concentrations of trace elements determined in lake water are often in ranges similar to those measured in the oceans the requirements for contamination-free sampling are thus similar (25, 26). Teflon-coated Go-Flo samplers were used. They were carefully cleaned with acid (0.01 M HN03) and high-... 

Figure 5.2. Cadmium (a) and Pb (b) concentrations in the ultrapure water used to condition Go-Flo samplers (different symbols refer to different bottles). Concentration was detected in aliquots of 50 ml of water where 300 pi of satured KCl were added(- - stands for the blank). Adapted from Capodaglio et al. (88).

Fig. 1-6. GO-FLO sampler made of PVC with optional internal Teflon-coating (Model 1080, General Oceanics). The samfrier passes through the water surface closed and opens at about 10 m depth via a pressure-activated releaser .

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). 

A Teflon-coated sampler (General Oceanics, 10-L Go-Flo) on a stainless steel hydrowire was used to obtain whole-water samples and samples for filtration from 16 points in the water column on each cruise. Samples were pressure filtered onboard ship, within a Class-100 laminar flow enclosure, in an all-Teflon column-filter holder (Savilex) through tared 0.4-pm track-etched filters (Nuclepore). Samples, both total P and total filtrable P, were acidified with high-purity HC1 (Ultrex) and immediately frozen. 

In our study, contact of the anoxic samples with oxygen was avoided. The samples were transferred from the samplers (Go-Flo, General Oceanics, 5 L) into bottles equipped with three-way taps under N2 pressure. The bottles had previously been flushed with N2, and they were completely filled. Filtration in the laboratory with acid-cleaned 0.45- xm cellulose nitrate filters (Sartorius) and a polycarbonate filtration unit (Sartorius) was also carried out under nitrogen gas. Most analytical determinations were performed in the laboratory on the sampling day. 

Spencer, M.3., Piotrowicz, S.R. and Betzer, P.R., 1982. Concentrations of cadmium, copper, lead and zinc in surface waters of the northwest Atlantic Ocean - a comparison of Go-Flo and teflon water samplers. Mar. Chem., 11 403-410. 

Fig. 1. Comparison of profiles obtained with Go-Flo (O) and CIT (X) samplers. Data points represent replicate extraction values. (From ref. 15.)...

Determination and Speciation of Cu and Zn. Water samples were collected with a sampler (Go-Flo, General Oceanics), which had been carefully cleaned with HN03. Samples were filtered in the laboratory (0.45... 

The sampler itself should be constructed from noncontaminating and, equally important, nonadsorptive material. The sampler should also be capable of being lowered through the sea surface closed so as to avoid contamination from the organic-rich sea surface microlayer. Unfortunately, there is no ideal sampler. The modified General Oceanics Go-Flo bottles widely used by workers in the field of oceanic trace inorganic analysis are often the most suitable systems that are commonly available. In some cases (e.g., for halocarbons), special devices have been constructed to allow uncontaminated withdrawal for the sample... 

GO-FLO PVC tube. Teflon coating optional, external rubber spring, for single use and in rosette-type samplers, COC, reduced flushing 1.7-100 3.9 7 ul Std., TM GO... 

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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