Environmental Engineering Reference
In-Depth Information
Temperature (
0
C)
ice
0
2
2
4
6
8
10
12
14
O
2
(mg L
-1
)
0
2
4
6
8
10
12
14
Redox (mV)
0
2
4
6
8
10
12
14
Total Iron (mg L
-1
)
0
2
4
6
8
10
12
14
Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb
FIGURE 11.7
Temporal patterns of temperature, O
2
, redox, and total iron in Esthwaite Wa-
ter (an English lake) over a year (redrawn from Mortimer, 1941). This type of figure is com-
mon for representing time series in lakes. The contours represent the boundaries of the val-
ues, with depth on the
y
axis and time on the
x
axis.
an excellent example of a reaction that goes against potential energy; CO
2
is transformed to sugar (with a higher potential energy) using the energy
of sunlight to accomplish the energy-requiring transformation.
OXYGEN: FORMS AND TRANSFORMATIONS
The element oxygen can be found in many forms in the natural envi-
ronment including water. The predominant form in the atmosphere is oxy-
gen gas, O
2
. It comprises about 21% of the atmospheric gas. Oxygen is
found in numerous compounds in combination with many other elements.
It is a major component of organic compounds and biologically relevant
inorganic compounds. As a result, it is important to understand the be-
havior and distribution of oxygen in the natural environment in order to
appreciate its impact on aquatic ecosystems.
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