Environmental Engineering Reference
In-Depth Information
TABLE 5.4
Average Chemical Composition of River Water throughout
the World
a
Current
Natural
Attribute
concentration
concentration
Pollution
% increase
Ca
2
14.7
13.4
1.3
9
Mg
2
3.7
3.4
0.3
8
Na
7.2
5.2
1.3
28
K
1.4
1.3
0.1
7
Cl
8.3
5.8
2.5
30
SO
4
2
11.5
6.6
4.9
43
HCO
3
53.0
52.0
1.0
2
SiO
2
10.4
10.4
0.0
0
Total dissolved solids
110.1
99.6
10.5
11
Dissolved nitrogen
21.5
14.5
7.0
32
Dissolved phosphorus
2.0
1.0
1.0
50
a
From Berner and Berner (1987) and Meybeck (1982). Concentrations in mg liter
1
.
erosion caused by watershed disturbance can be retained for decades,
prolonging the recovery time from sediment pollution events (Trimble,
1999).
The effects of change in temporal and spatial scales on stream habi-
tats can be linked to processes of erosion and habitat change, leading to
a hierarchical classification of stream habitats (Fig. 5.19). Such classifica-
tion provides a useful framework with which to approach the links be-
tween river hydrology and aquatic ecology and a template for the inter-
action of organisms with habitat (Gregory
et al.,
1991). Consideration of
scale is a vital component for understanding patchiness in stream ecosys-
tems (Stanley
et al.,
1997), scale controls chemical transport (Dent
et al.
2001), and may be useful in the study of water quality (Hunsaker and
Levine, 1995).
TABLE 5.5
Total Organic Carbon Export by Rivers for
Different Terrestrial Environments
a
Average total carbon
Total carbon load
export (g m
2
year
1
)
(10
12
g C year
1
)
Environment
Tundra
0.6
5
Taiga
2.5
40
Temperate
4.0
88
Tropical
6.5
241
Semiarid
0.3
5
Desert
0.0
0
Total
13.9
379
a
From Meybeck (1982), Reprinted by permission of
American Jour-
nal of Science
.
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