Environmental Engineering Reference
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assigning systems to three trophic categories. The method has not been ap-
plied to macrophyte-dominated streams.
Trophic categorizations for groundwater and wetlands have not been
developed. Trophic state may correlate to biological characteristics of wet-
lands. For instance, some oligotrophic, nitrogen-limited wetlands contain
carnivorous plants that utilize captured insects as an N source. Also, P fer-
tilization of the Everglades can lead to shifts in plant and periphyton com-
munities. Thus, it should be possible to create biologically meaningful clas-
sifications of wetland trophic state.
Productivity of groundwaters is generally based on the influx of organic
carbon and O
2
, so more eutrophic groundwaters could be characterized by
high supply rates of organic C, low O
2
, and potentially high microbial pro-
ductivity. The rates of microbial activity may actually decrease in aquifers
that are anoxic because anoxic carbon cycling is less efficient than respira-
tion using O
2
. Aquifers that are eutrophic because of high organic carbon
input could lack a complex invertebrate community due to anoxic condi-
tions, so trophic state may correlate to biological characteristics.
WHY IS NUTRIENT POLLUTION RESULTING IN ALGAL BLOOMS IN
LAKES IMPORTANT?
The stimulation of algal blooms and creation of anoxic hypolimnia in
lakes leads to many problems. As mentioned in Chapter 1, the monetary
A
4
3
2
1
40
45
50
55
60
6
B
5
4
3
2
1
0
40
45
50
55
60
Trophic State Index
FIGURE 17.4
Relationship of trophic state index (determined by the method of Carlson,
1977; Fig. 17.2B) and water odor of surface (A) and hypolimnetic (B) samples from six
Kansas reservoirs. Water odor was ranked by human testers, with a higher rank indicating
lower drinking water quality (reproduced with permission from Arruda and Fromm, 1989).
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