Surface soil samplers

In most cases, if soil samples are needed, only surface samples are collected. An exception would be harvesting root crops where all residues in the top 6 in of soil would be sampled. A typical surface soil sampler is shown in Figure 2. It is the residue adsorbed on small particles (<150 o.m), which could cling to moist skin, which causes the most exposure to workers. After sampling, place a flag in the center of each sampled location to mark the area against future sampling. After the surface layer has been collected, the soil is sieved to collect the fraction <150 lam and the remainder of the soil is discarded. Maintain separate sieves and collectors for treated and control plots to prevent contamination of the control samples. 

The method above, however, is not suitable when one needs a precise study of the vertical distribution of pesticides. Generally, the concentration of pesticides in paddy sediment is highest at the surface. Special care is required to avoid contamination with surface soil when the sediment is collected. The sediment core should be collected in two stages. First, a pipe with a diameter greater than that of the core sampler is inserted in the sediment and then water inside the pipe is removed gently with a syringe, pipet, etc. Next, a layer of surface soil (1-3 cm) is taken with a spatula or a trowel and then subsurface soil is collected with a core sampler to the desired depth see also Figure 4. 

Samples should be collected from the surface layer 0-5 cm deep with a soil sampler having a diameter of 10 cm at five to eight locations. 

Surface soil can be collected with a scoop or cookie cutter. The scoop sampler is convenient for collecting a grab sample and transferring it directly into a collection container. A cookie cutter is a rigidly framed apparatus that can be sunk into the... 

It is often important to quantify the contamination of pore fluid in the unsaturated soil 2one, where monitoring wells are ineffective. In this region, suction cup lysimeters are useful (7). These samplers consist of a porous cup, typically ceramic, having two access tubes which are usually Teflon. One access tube provides a pressure-vacuum, the other discharges the sampled fluid to the surface. The porous cup, typically between 2 and 5 cm in diameter, is attached to a PVC sample accumulation chamber. 

The simplest adequate sampling device should be used. Where the contaminant Is believed to be on the surface, a soil punch or trowel may be used. If the contaminant Is soluble or Is expected to be located more than a meter below the surface, a truck mounted core sampler such as a split spoon sampler should be used. 

Soil samples were collected along a traverse over the Honerat kimberlite and extended off the kimberlite approximately 75 m SE and 225 m NW from the pipe s centre (Fig. 1). Although it is common practice to collect samples from upper B-horizon soil (Levinson 1980 Bajc 1998 Mann et al. 2005) our samples were collected from C-horizon soil because GAGI samplers were placed at a depth of 60 cm (well below the B horizon). Within 8 hours of sampling, a portion of each soil sample was mixed with Milli-Q water (1 1) to create a slurry. The values of pH and oxidation-reduction potential (ORP) were determined in each slurry. Ammonia acetate leach of the soil samples were performed at Acme Analytical Laboratories, Vancouver, where 20 ml of ammonium acetate was mixed with 1 g soil sample and elements were determined by inductively coupled plasma-mass spectrometry. The GAGI samplers installed at Unknown were placed in piezometers and submerged in water at a depth of approximately 1 m below ground surface. 

Direct NIR or MIR measurements of whole soil can be made using attenuated total reflectance (ATR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) samplers. This type of measurement detects only components on the surface and so has severe limitations when information about the bulk soil is needed [4],... 

Composite samples are typically collected for soil stockpile or surface area characterization. Twenty-four-hour composite samples of water may be collected with automated composite samplers from streams or process piping composite samples may be made of several grab samples collected from different depths in a soil boring. 

To sample with airtight coring devices, we must have access to exposed soil, which may be the ground surface, the bottom and sidewalls of an excavation, the stockpile face or side, or soil in the excavator bucket. We may also apply this technique for sampling of subsurface soil brought to the ground level in a split spoon sampler. 

The usual method for obtaining samples at significant depths below the surface is to push or drive a pipe or tube into undisturbed soil at the bottom of a drill hole. Of course, this process disturbs the soil, particularly when the pipe is heavy walled. Many different kinds and sizes of samplers are used, and the most common is shown in Figure 1.1. This sampler is commonly called a split spoon. When used with the dimensions shown, and hammered into the soil by a free falling, 140 pound weight, dropping 30 inches, this is the Standard Penetration Test (see ASTM Standard D.1586,... 

In fine, uniformly graded soils, large thin wall samplers pushed slowly and steadily offer the best chance for success. Close to ground surface, chunk sampling from test pits is most feasible. 

Under dry conditions a higher proportion of the DCPA was detected in the particles, however, after irrigation the total amount detected in the sampler increased as did the proportion in the vapor phase (Table 4.9). This observation is consistent with laboratory studies of the effect of soil moisture on evaporation from the soil surface. It was estimated that over the 21-day experimental period, evaporative flux from the treated area accounted for 10% of the herbicide applied. 

Piston sampler of hydraulically operated type, (a) Lowered to bottom of borehole, boring rod clamped in fixed position at the ground surface, (b) Sampling tube after being forced into the soil through water supplied through boring rod. 

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