Geoscience Reference
In-Depth Information
A
Figure 5-12.
Close-up view of
Sphagnum warnstori a
moss (see Color Plate 5-12). This moss forms red
tussocks at the edge of oligotrophic bogs. Karelia,
Russia; photo courtesy of E. Volkova.
B
Figure 5-13.
Tropical rain forest in northern Brazil
near Manaus. The forest is inundated for months at a
time during the rainy season; l ood waters bring
nutrients to support the rich species diversity and high
productivity of this wetland environment. Photo
courtesy of K. Buchele.
Figure 5-11.
Hydric soil proi le from a playa mud l at
at Dry Lake, west-central Kansas, United States (see
Color Plate 5-11). A. Freshly dug pit,
30 cm deep,
showing distinct horizons from the surface downward.
Note the redoximorphic iron accumulation (*) and dark
gray color at depth. B. Clump of greenish-gray (5 GY
6/1), clayey silt with ferric iron accumulation (*).
Photos courtesy of B. Zabriskie.
∼
et al. 1995). Positively charged cations, such as
ammonium (NH
4
+
) and potassium (K
+
), are
absorbed and held loosely by organic mole-
cules. The same principle is used for water sof-
tening, in which Na
+
in the softener i lter is
exchanged for Ca
2
+
in hard water. The stored
cations may be retained for long periods,
or taken up by other chemical or microbial
activity, or become buried in the wetland sedi-
ment. In this way, organic-rich hydric soils i lter
Organic matter has quite high cation exchange
capacity. What this means practically is that
organic-rich hydric soils act like sponges to soak
up excess nutrients and other pollutants (Welsch
