Deep samples

Comparison with other Studies. How do the results of our investigation compare with similar studies Our results corroborate the data provided in a similar study of the effect of UV-B on primary productivity in the southeastern Pacific Ocean (35). In the latter study, it was noted that enhanced UV-B radiation caused significant decreases in the productivity of surface and deep samples. Compared to ambient, primary productivity decreased with increasing doses of UV-B. In another study in which in situ experiments using natural Antarctic phytoplankton populations, it was noted that incident solar radiation significantly depressed photosynthetic rates in the upper 10-15 meters of the water column (36). It was also found that the spectral region between 305 and 350 nm was responsible for approximately 75 percent of the overall inhibitory effect. 

For obtaining deeper samples or large numbers of samples, it may be practical to use a mechanical sampler. Truck-mounted samplers are available and can be used to take samples meters deep. Other more robust samplers may be necessary if very deep samples must be taken. 

If contamination is the reason for sampling, samples at depth along the transect line will also be required. Depending on the soil depth, depth to the water table, the severity of contamination, and the type of soil, deep samples may need to be taken at each location. As with the transect, depth samples must be taken until the contaminant or analyte of interest is found to be at background levels. Thus, several depths may need to be taken at each location along the transect. 

Fig. 3. Selection of sampling sites (Modified after Darnley et al. 1995). Schematic outline of sampling pattern and sampling pit for geochemical reference network. The sample pit applies to all residual soil locations. Deep sample (C) a 25 cm thick section within a depth range of 50 cm - 200 cm.

The second pattern evident in Table II is that the photochemically mediated transfer of carbon into the microbial food web is more pronounced for deep-water marine DOM than for surface water marine DOM. In two studies that explicitly compared relative photoreactivity of surface and deep samples, the biological lability of deep-water DOM was consistently greater after exposure to sunlight, whereas surface waters typically... 

Several examples in which DOM was adsorbed to a single type of XAD resin can be used to illustrate some basic trends. Stuermer and Harvey (1977) adsorbed DOM from surface and deep samples in the Sargasso Sea on a column of XAD-2 resin, which was back-eluted with NH4OH and CH3CH2OH to recover the hydro-phobic acid fraction (HbA) and hydrophobic neutral fraction (HbN) of marine DOM. HbA and HbN fractions accounted for 4.5% and 3.4%, respectively, of DOM in the surface water sample. In contrast, 22.5% of DOM in the deep water sample was isolated as the HbA fraction, and an additional 8.2% of DOM was isolated in the HbN fraction. Slauenwhite and Wangersky (1996) used XAD-2 resin to adsorb DOM from coastal surface samples in Halifax Harbour. Using both NaOH and CH3OH as eluents, they were able to recover less than 15% of DOM (HbA and HbN combined). Druffel et al. (1992) used XAD-2 resin for adsorption and NaOH for desorption of DOM to recover 22% + 2% of marine DOM from four samples... 

Figure 6.9. Mean concentrations of dissolved species in Checker Reef pore waters and overlying seawater. Vertical bars indicate standard deviations. "FR" and "BK" refer to seawater samples from the fore and back reef stations. Other symbols refer to l-and-2 meter deep sampling stations across the reef (D is the midpoint of the reef). (After Sansone et al., 1990.)...

An explosion resistance pool must be more than 3m in diameter and 2m deep. Samples are exploded at a depth of 1 m in the center of the pool. 

The discrepancies between the methods are even more marked in the deep samples, where the persulfate values are close to 0.5 mg, and the dry combustion values range between 1 and 1.7 mg carbon/1. The discrepancies between the two methods were pointed out almost as soon as enough numbers were in the literature to permit a comparison (30). However, North American workers have chosen either to ignore the difiFerences or to assume that the Russian values, although higher, showed the same invariance with depth as was claimed for the American values (32). Such an assumption was only possible because the Russian method was tedious, and so few deep samples were taken at any one station that a meaningful depth profile could not be established. Even with the sparse data available, it should have been noted that the difiFerence between the two methods was much greater in the deep water than at the surface. 

Davy and Stokes (1977) also reported the determination of sulphur dioxide in the soil air overlying sulphide mineralisation. The levels measured were low, the contrast was poor, the samples were few and the traverses were not repeated. Despite very long sampling times (24-96 h) and deep sample holes (1.5-7.6 m), the results proved to be ambiguous. 

Deep sampling was also recommended by Jones and Drozd (1983), who collected soil gases from holes drilled to 4 m. There are, however, obviously many circumstances in which deep sampling is not possible, such as areas of shallow water table. Whilst it may be argued that shallow sampling must then suffice (Gregory and Durrance, 1985), it may be that in such circumstances gas sampling is not an appropriate procedure. 

An example of the power of such tracers is in the "dating" of abyssal water using C. Stuiver et al. (1983) have measured the distribution in dissolved inorganic carbon in deep samples from major ocean basins (Fig. 9-12). These data were used to calibrate a box model which indicated that the... 

At about fhe same time, lin and coworkers [84] at fhe National Cheng Kung University in Tainan, Taiwan published fheir version of a chip, which is similar to that of Harrison s group in Alberta. This group had extensive experience in flow injection analysis and on-line analysis wifh conventional electrophoresis. In their design, a 3 mm wide X 40 pm deep sample inlet channel (SIC) was etched for sample flow-through, which in turn was connected to fhe electrophoretic manifold of 80 X 40 pm cross section, in a configuration similar to the Alberta chip (see... 

T correction made assuming 18 kcal/mole apparent activation energy on experimental values determined at 22°C (Fig. 36). r estimated from deep-burrowing (>2-3 cm) polychaete abundance in box core taken within 20 m of chem core. Difference between estimated and actual model value usually is equivalent to 2-3 more individuals in a faunal sample. DEEP sample higher values use Pherusa abundance only. 

Still another heated sample holder was described by Wendlandt and. Hecht (1). It consisted of a block of aluminum, 50 mm in diameter by 25 mm thick, into which was machined a 25-mm by 1-mm deep sample well, A 35-watt stainless steel sheated heater cartirdge embedded in the main block of the holder was used as the heater. The same two-thermocouple systems, one for the temperature programmer and the other for sample temperature, was employed. For samples which evolved gaseous products, a Pyrex or quartz cover glass was used to prevent contamination of the integrating sphere. 

Fig. 20. Log plot across one of the Magnolia pay zones showing gamma ray, lithology, resistivity, and associated gas 6 Cc, from two undersaturated oil MDT samples ( ). Calculated fluid densities at reservoir pressures are 0.639 and 0,644 g/cra for the shallow and deep sample respectively. The of the few gas...

Samples from reservoirs, ponds and lakes are taken from various localities and various depths, usually by means of deep sampling devices. It is not recommended to take an average (pooled) sample since substantial differences in the water quality in different positions of the point samples may cause chemical reactions and mispresent the final results. 

Samples from drills (probes) are taken by a narrow deep sampling device or a pump. The samples from drills in which water has been present for a long time or whose outlet was not well closed ar.e not reliable. 

Nondescanned (or direct ) detection solves a problem endemic to fluorescence scattering in deep sample layers. Fluorescence photons have a shorter wavelength than the excitation photons and experience stronger scattering. Photons from deep sample layers therefore emerge from a relatively large area of the sample surface. To make matters worse, the surface is out of the focus of the objective tens. Therefore the fluorescence cannot be focused into a pinhole. 

Fig. 7. Variation of vs. 5 B for DSDP cherts. Despite the scatter, a positive trend is present. This trend is consistent with diagenesis under variable conditions (see text) high T and closed system for deep samples having low and low 6 B values and low T and seawater dominated pore fluid for samples above 700 mbsf having high and high 6 B values.

Determination of the residual pore water pressure. (From Kirkpatrick, W.M., and Retmie, I.A., Stress relief effects in deep sampling operations, Proceedings Underwater Construction Conference, University College, Cardiff, 1975.)... 

Advantages of NIR include speed, little or no sample preparation, solvents and reagents are rarely needed, high dynamic concentration range, and deep sample penetration. NIR obeys the same selection rules as mid-IR. Only molecules that exhibit a dipole moment will absorb NIR radiation. 

PA-FTIR depth profiling results are consistent with the known layer stmcture of a packaging laminate film and an adhesive label [477]. Doublelayered PET/PET, PP/PET and PET/PP laminates were studied by PA-FTIR [478]. PA-FTIR and DSC identified a skin layer and a core in injection moulded PET plates [479]. Plastic-coated paper was analysed by both PA-FTIR and DRIFTS allowing for shallow- and deep-sampling, respectively [453]. PA-FTIR is also a suitable tool for the analysis of polymer films used as a barrier coating on beverage and food containers at variance to specular reflectance measurements surface flatness is not critical. 

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