Traps, Mistakes, and Errors - Field Sampling: Principles and Practices in Environmental Analysis - page 284

11.5.1. Using GPS
A particularly effective way to solve many of these problems is with the use of GPS.
Fields can be unequivocally located using GPS, and waypoints or sampling sites can be
located and their positions programmed into the GPS instrument being used. In this way
the location of the field and sample sites therein are known and the sampler can locate
them by referring to the GPS unit. Both experienced samplers and inexperienced
samplers will need training in reading, interpreting, and recording GPS data. It is
essential that the person sampling be able to accurately read and record GPS data in the
project notebook. This is particularly important if the sample is not taken at the exact
location specified but nearby, or if the field is to be repeatedly sampled. While learning to
use a GPS instrument it is important that samplers practice sampling under the
supervision of an experienced sampler.
It might be thought that having the sampler physically mark the sampled sites would
solve this problem—it does not. With inexperienced samplers, checking sampling
markers placed at the sampling sites will show that the field was not sampled correctly.
The solution to this problem would be for the field to be resampled correctly. Time is an
important component of sampling, and resampling may not be possible for several weeks
after the original sampling event because of weather or work schedules. Thus, the
original samples will not be comparable to the later samples. For some situations it may
be critical for the success of the sampling and remediation process that samples be taken
at a particular time. In this case resampling can have a large detrimental impact on the
whole sampling project [2]. Common mistakes made by inexperienced samplers are
summarized in Table 11.3.

11.5.2. Safety
Safety will also be of special concern, especially for inexperienced field samplers, and
the first concern is for the safety of the person doing the sampling. This is due to the fact
that some samples or fields can be dangerous to human health, and this fact may only be
discovered after analysis is complete. All workers must observe all safety rules at all
times. In addition to this being important for the person doing the sampling, it is also
important for persons helping with the sampling. The second concern is for the safety of
sampling equipment and the samples already taken. In the sampling process money and
time is expended in purchasing and maintaining sampling tools and in obtaining the
samples.

TABLE 11.3 Mistakes Made by the Inexperienced Sampler

Field Not finding the field and the corresponding field map

Sampling Taking samples from the incorrect places in the field

Sample size Not taking samples from the same depth at each site