Presampling - Field Sampling: Principles and Practices in Environmental Analysis - page 65

one example of surprises that can be unearthed if an adequate history of the
field is not obtained.
As part of the history of the field find out about the soils present and their characteristics.
This information can be obtained from soil surveys. If the soil is not the same as
indicated in the soil survey, it is either fill or disturbed by various activities on the field.
Knowing the soil—particularly its texture—will help determine the type of sampler
needed. This information will also be required to determine how deep sampling must be
done or is likely to be needed. The soil survey will also indicate if water is likely to be
encountered during sampling [9]. Information in the soil survey will also be needed in
any modeling of the field.
3.7. SAMPLING TOOLS
During the presampling stage decisions about sampling tools and their sources need to be
made. Solid materials, particularly soils, will require different samplers, depending on
their characteristics. Water and air will each require different samplers, although in many
cases no sampling tool will be needed.
On the basis of the characteristics of the soils present or likely to be present as
indicated by the soil survey, what type of sampler is likely to be most useful? In part this
will be determined not only by the texture of the soil but also the moisture levels likely to
be encountered. Dry, sandy soils will require a different type of sampler than wet, clayey
soils. Likewise, a stony or rocky soil will require yet another type of sampler. Another
important consideration is the depth to which sampling is to occur. The sampler must be
able to sample to the maximum depths needed to account for all the contaminant likely to
be present. (See below and Chapter 5 for more detailed information about samplers.)
Contaminant type, whether inorganic or organic, will affect the choice of sampler. For
inorganic components the metal used in the sampler will be important. If, for instance,
zinc is the component of interest the sampler must not have zinc in it. Many different
types of metals are used in the construction of samplers, so it is important to be sure that
the composition of the sampler is compatible with the sample being taken. If the
component is organic, there are two other considerations. The first is that the sampler (or
sampler liner, if used) is not adding organic material to the sample. The second occurs
when the sample contains volatile organic compounds (VOCs). In this case the sampler
should, as much as possible, minimize the loss of the organic components during the
sampling process [9].
3.7.1. Soil Samplers
There are three different basic types of soil sampler heads—simple auger, bucket auger,
and core. The three different types are shown in Figure 3.6. (See also Figures 5.5 and 5.6
in Chapter 5.) A simple auger looks like an old-fashioned wood drill bit. It can be used in
moist and wet fine-textured and rocky soils but does not work well with sandy soils,