Grab samplers

Sediments from the bottom of streams, rivers, lakes, estuaries, and oceans are collected with a bottom grab sampler or with a corer. Grab samplers are equipped with a pair of jaws that close when they contact the sediment, scooping up sediment in the process (Figure 7.5). Their principal advantages are ease of use and the ability to collect a large sample. 

Figure 5 (a) Ekman-Birge grab sampler for clay or loamy sediments and (b) Smith-Mcintyre grab... 

The devices used for sampling of solid samples (sludge, sediment, and soil) are usually grab samplers or corers. Box corers or multicorers can be employed if more detailed information on the spatial distribution of the analytes is needed. The samples are stored in the dark at 4 °C or more commonly at -20 °C, preferably in glass containers [53]. Very often, solid samples are also dried or lyophilized prior to storage. 

Sediment samples are collected synoptically from both exposed and reference areas (e.g., by the use of remote grab samplers operated from a vessel, or using divers for locations where grab sampling is impractical). Spatial heterogeneity in sediment contamination and toxicity render coincident sampling extremely difficult to interpret, and such sampling is not recommended. Appropriate quality assurance /... 

Portable sampling devices were categorised by Nielsen and Yeates (1985) as grab samplers, suction lift devices and positive displacement mechanisms. A brief review of each category is given below. 

Sample HR (3.70% organic carbon) was collected with a Shlpek. grab sampler from a marginal cove In the Hudson River approximately 60 river miles north of the southern tip of Manhattan (1). The... 

Sediment samples were collected using a grab sampler (which samples approximately the top 10 cm) aboard Old Dominion University s research vessels, ODU-1 and Linwood Hoi Con. The sample locations are shown In Figure 1. The samples were stored frozen In clean, solvent-washed jars until analyzed. Creosoted wood samples were collected from areas adjacent to the Elizabeth River (Figure 1). Three samples of refined creosote and one sample of coal tar were also analyzed. Creosote samples from Atlantic Wood Industries, the remaining operative creosotlng facility on the Elizabeth River, were not available. The woodstove soot sample was obtained from a domestic woodstove in which predominantly hardwoods were burned. 

The lake sediment has been taken from Lago Maggiore (Italy) at one of the deepest basins in the northern part of the lake near Cannero (from a depth of ca. 280 m). A modified Eckman grab sampler was used. The sample collected from this depth is typical for a fine particle anaerobic deep-lake sediment. There was no local source of pollution in the vicinity of the sampling area. Immediately after collection, the sample was air-dried, crushed and sieved through a sieve with apertures of 90 pm and set aside for further treatment. 

All sampling locations are given in Table 1 and are illustrated in Figure 1. The sediment samples were taken in 1993/4. Surface sediment samples (Sl-Sll, S13, S14, H1-H4, H6, H9, Tl, T4-T6) were collected with an Ekman-Birge-grab sampler yielding up to 20 cm of the top layer. 

Tab. 1 Samples of Havel and Spree river sediments. Sampling devices EB = Eckman-Birge-grab sampler NF = liquid nitrogen deep freeze method.

Four sediment samples were taken in 1998 and 1999 from three locations at the Teltow Canal in Berlin, as indicated in Fig. 1. In addition to the surface sediment samples T1 and T3 taken by means of a 4L Ekman-Birge grab sampler a short sediment core T2 was obtained by using a tube coring device. The sediment core was subdivided into an upper part T2a (0-3 cm) and a lower part T2b (3-10 cm), that represents an older accumulation time between 1980 and 1990. 

EB ECD EDTA EI+ EPA EPTC ESR EU Eckman-Birge-grab sampler Electron capture detector Ethylenediaminetetraacetic acid Postive electron impact ionisation Environmental protection agency (USA) S-Ethyldipropylcarbamate Electron spin resonance (spectroscopy) European union... 

Rio Negro, Amazon River system Obtained from J. Edmond (MIT). The sediment (mixed silt, clay, and sand) was taken upstream of Manaus at 03°07 S, 60° 06 W. The sample was obtained with a grab sampler. 

The sediment sample used in the first interlaboratory trial was collected in Yrseke, The Netherlands, with grab samplers, wet sieved at 2 mm and air dried at room temperature (ca. 20 °C). The air-dried material was then ground, sieved at 90 pm and homogenized before bottling. The bulk homogeneity of the sediment was tested by X-ray fluorescence (XRF) by determining the major components. 

Surface sediments can be collected intertidally or by means of a variety of grab samplers from a vessel. Because PCB concentrations in sediments can show a patchy distribution, several grabs from one location are normally combined to one pooled sediment... 

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