Corer

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. 

Schematic diagram of a piston corer in operation. The weight of the corer is sufficient to cause its penetration into the sediment, while the upward motion of the piston allows water pressure to help force the sediment column into the barrel of the corer.

Surface samples were collected in snow pits under ultra-clean conditions described elsewhere [13] with the exception that samples for anion analysis were collected in polystyrene cups precleaned without the use of acids. Ice core samples were cleaned to remove surface contamination using the "dry-core" procedure involving rinsing and melting of exterior surfaces with ultra-pure water [13]. Shallow-depth firn cores are permeable and the dry-core rinsing is unsuitable. Therefore an inner core of 2.5 cm diameter was taken from intervals of the 7.6 cm diameter South Pole firn core using a specially-built precleaned stainless steel corer within a -15 °C cold room. Prior to this coring, exposed ends of core sections were shaved away with precleaned stainless steel chisels. 

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. 

Instructions can be found in the AOAC Official Methods of Analysis (Padmore, 1990, p. 69). A pointed corer consisting of a single or double tube, or slotted tube and rod, is used to remove a diagonal core from end to end of the horizontal bag. Bulk feeds should have ten or more cores from different regions. The sample should be stored in such a way that deterioration and change in composition are prevented (BS 5766, 1979). 

Table 1.1. Comparison of Alexander pattern and modified design of silage corer.

Fig. 1.2. (a) Stainless still silage corer. Units in mm (and inches (in) when appropriate). 

Because a large number of cores was required for this study, we chose to economize on the number of samples for 210Pb and Hg analysis by sectioning most of the cores at coarse intervals. Historic trends in Hg deposition were provided by a few cores analyzed in stratigraphic detail, whereas the coarsely sectioned cores provided the spatial pattern in Hg accumulation across each basin at a few discrete time intervals. The samples from the coarse-interval cores were homogenized and analyzed for Hg and 210Pb content in the same manner as the detailed cores. Detailed cores were collected with a 10-cm-diameter corer, and the coarse-interval cores were obtained with a 5-cm-diameter corer. The number of cores collected from each lake is shown in Table II. 

A gravity dredge was used to recover samples of the soft, dark, organic-rich muds that have accumulated thinly over the inundated clay soils of the watershed. In some locations, soft deposits such as alluvial silts could be recovered with a 2.5-inch-diameter gravity corer. 

After collection, samples were divided into 5-cm sections or into sections determined by changes in sample matrix. Only sediment from the interior of the core (not in contact with the corer) was used to avoid possible contamination from the polycarbonate and from sediment fines forced along the wall of the tube. Sectioned samples were stored in solvent-rinsed bottles at 4 °C until analyzed. Some samples used in this study were collected from reaches of the submerged riverbed (where PCBs were deposited before the reservoir was filled). Sample locations (Figure 1) were determined in relation to buoys placed and maintained by the U.S. Army Corps of Engineers. Samples used in this study were limited to those found to be contaminated with at least 1 xg/g of total PCB to minimize quantification error during weight-percent calculations. 

Various new devices that have been used in soil sampling include a gravity-driven, hydraulically sampled multi-piston corer for fine-grained soils [11] and time-series trap that can collect 21 samples of soil at programmed intervals [12]. 

Peter Strasser, Sasha Corer, Qun Fan, Konstantinos Chondroudis,... 

Hollow tubes or casings that are used to collect soil or sediment samples. Small soil corers are normally pushed into the soil or sediment by hand-held tools. See also Sediment core sample. (PIANC, 1997). Volume 2(9). 

Sediment sample collected with a corer. The advantage of corers is that they preserve the vertical profile of the chemical constituents of the sediment. This allows for sediments to be sub-sampled to specific depths. Volume 2(9). 

Large-scale soil sampling equipment (augers, corers, split spoons, and core barrel samplers)... 

FIGURE 1.9 Collection of sediment samples from shallow water with a manual corer. 

The fish were taken by hook and line, poisoned, or netted. They were wrapped in aluminum foil, quick-frozen, and shipped to the laboratory packed in dry ice. Mud was taken usually down to a depth of 3 inches by scoop or wide-mouth container. Soil and rice field mud samples were taken with a %-inch i.d. soil corer down to a 3-inch level. Fields were crossed diagonally, and subsamples were taken at regular intervals. The samples were packed in wide-mouth, screw-cap jars with aluminum foil inserts. 

The northern portion of Chesapeake Bay was studied. This upper section of the bay can be classified as a classic salt-wedge type estuary (15). The humic materials used in this study were extracted from several cores of sediments. Two one-meter cores gravity corer. The cores of sediments were then divided into sections and squeezed under nitrogen to remove most of the interstitial water. The squeezed sediments were then dried, weighed and washed with distilled water. The sediments were then washed with 0.5N KCl to remove iron hydroxides, carbonates and exchangeable cations from the clays. Some of the fulvic acids are lost in this acid wash procedure. The humic materials were then extracted from the remaining solids by a O.IN NaOH solution. 

Core 1 and Core 7 had two cores removed from box corer for profile study. 

There are, however, relatively few signs that this has moved from being a niche activity to being part of the mainstream world of investment. For example, only three of 35 SRI research organizations evaluated by SustainAbility in Values for Money are found to currently analyze the link between social/environmental issues and material impacts on investment value drivers (Beloe et al., 2004). These are SAM Research, Innovest, and CoreRatings. These have the greatest potential to cross over into more widespread use among mainstream investors. 

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