tests for radioactivity can be performed using the Radiac Set, AN/PDR--27 (see
figure 6-16). This instrument measures low-intensity gamma radiation within the range
of 0 to 500 miIIiroentgens per hour.
Figure 6-16. Radiac set, AN/PDR-27.
b. Biological Agents. The laboratory identification of most microorganisms is
difficult and time-consuming; consequently, quick identification of biological agents in
the field is not yet feasible. Biological agents may be disseminated by such means as
means are employed, the possibility that biological agents are being used must be
considered. The results of biological contamination are not so readily evident as are
those of chemical contamination; therefore, detection is much more difficult. One sign
that may be indicative of biological contamination in water is a sudden and otherwise
unexplained increase in the chlorine demand (see paras 2-4b, 5-10b).
c. Chemical Agents. Contamination by chemical agents usually, though not
always, leaves significant signs that should arouse immediate suspicion. These include
a drastic lowering of the pH of the water (less than six), odors, and tastes characteristic
of chemical contamination, and dead fish or animals in significant numbers. If chemical
contamination is suspected, tests should be initiated immediately to confirm or rule out
the contamination. The conduct of chemical tests on water was discussed in Lesson 4.