Sampling - Field Sampling: Principles and Practices in Environmental Analysis - page 120

containing gravel or other large stone fragments, in which they can be used to depths of
15 to 20 cm (6 to 8 in.). Auger-type samplers can have the same variations as the core
samplers mentioned above.
Another type of auger sampler is one with an integral bucket. These samplers are
screwed into the soil and a sample is collected in the bucket (Chapter 3, Figure 3.6). The
sampler may be fixed to a T-type handle with a definite length of pipe between the handle
and the auger. Some people keep a series of samplers of different lengths for different
jobs. In situations in which there is a constant need for samplers with different lengths the
lengths are threaded in such a way that additional pipe can be added or removed to make
the sampler longer or shorter.
For very deep sampling in complex situations it is imperative that a standard well-
drilling outfit be used [11, 12].
No matter which type of sampler is being used, it is important to keep samples
separated and identified. Samples should not be allowed to become cross-contaminated
during the sampling procedure. The sampler therefore needs to be cleaned after the
collection of each sample.
Generally speaking there is no correlation between the precision or accuracy of
analytical results and the type of sampler use. Because of this, soil scientists familiar with
the area in which the field is located can give excellent guidance as to the best type of
sampler to use for the local soils and regolith [1].
5.7. SAMPLE AMOUNT
The amount of sample taken will be determined by two factors. How much sample is
needed for analysis, and what type of component is the sample to be analyzed for?
Because of these considerations the absolute size of the sample cannot be given. The
amount of sample needed in the field laboratory and the commercial laboratory are added
to obtain the total amount of sample needed. This may change, however, depending on
the sample container requirements, because some samples must fill the container
completely and this determines the amount of sample taken. In those cases in which
multiple analyses are called for, more sample is also needed.
In sampling, several “cores” will be combined to make a sample to be analyzed. For
instance, three or four cores might be taken from each grid in Figure 5.7. These would be
placed in the same bag as a single sample for analysis. Figure 5.8 shows three cores and a
core still in the sampler. If the cores are not about the same size, the larger core sample
characteristics will dominate the sample and analytical results. This can lead to dilution
or concentration of the component of interest. In either case the resulting analytical data
will not give a true picture of the area being sampled. It is