Sampling - Field Sampling: Principles and Practices in Environmental Analysis - page 139

standpoint of the safety of the personnel adding the contaminant and the person doing the
analysis. In such cases, a surrogate may be added to the sample. This is a compound that
is not toxic (or is very much less toxic), but has the same or similar physical, chemical,
and biological properties as the component of interest. The surrogate allows one to
determine if there is any change in the sample between sampling and analyses without
undue danger [25].
Liquid or solid contaminants or surrogate compounds added to soil or regolith
materials do not cover them uniformly. Only analysis of the whole sample will give an
accurate picture of the fate of the contaminant or surrogate. A subsample may give an
erroneous result because of nonuniform distribution, which can occur even if the sample
is ground, sieved, and mixed exhaustively.
5.17. LABELING
Labeling seems like a simple part of any sampling activity. Incomplete, unreadable, and
missing labels cause error, however, as well as a great deal of wasted time and money.
5.17.1. Labeling a Sample
Labels must include reference to the field position from which the sample was taken and
to the page in the project notebook on which sampling is described. Numbering of the
designated sampling areas, as indicated in Figure 5.9, is done sequentially. The sample
areas below the surface are indicated by Greek letters. In this instance, one would know
that sample 15 β is the second sampling area below surface area 15. This gives an
unequivocal designation and location to this sample. The question might be asked as to
why Greek letters are used when the Roman alphabet will do. What most researchers find
is that they have use for the alphabet in designating other aspects of the sample. We
therefore save our alphabet for these uses and use the Greek alphabet for designating
subsurface sampling areas. A sample number must be unique, but allow for easy lookup
when needed.
The project notebook page on which the sampling is described is on the label, which
must also show the date and time sampling was performed as well as who took the
sample. Additionally, where it is to be stored and shipped must be shown, as well as the
shipping route.
There are other considerations in deciding on how to label a sample. First, during
handling, will the samples be subject to wetness, even if only from workers' hands? The
answer is always yes. This means that any numbering or other designation that can be
removed with water will be removed, or at least smeared until it is no longer
recognizable. The first step is thus to use only “tested” permanent markers (e.g., a test
sample number is applied to the sample container when it is dry, and then it is wiped with
water, soap and water, etc.).
Another strategy is to put the sample label in several places on the sample container.
Thus a copy of the label can be put on the bottom of the sample container, since people
will not be rubbing against the bottom as much as the sides. The drawback is of course is