Geoscience Reference
In-Depth Information
2004). As an added benei t, treatment wetlands
may also provide habitat to local fauna in some
cases.
Treatment wetlands are employed to i lter
and decontaminate water from agricultural and
livestock facilities or treat storm-water runoff
(Natural Resources Conservation Service 2010).
These facilities are generally located in upland
regions away from l oodplains and take special
precautions in highly permeable soils to mini-
mize the risk of accidental contamination of
surrounding areas (U.S. Environmental Protec-
tion Agency 2004; Scholz and Lee 2005).
The construction of treatment wetlands
requires careful engineering, taking into consid-
eration the soils, hydrology, topography and sur-
rounding land uses. Typically, construction
requires excavating the land surface to create
a depression or embankments, appropriately
grading the surface, transporting in a suitable
layer of top soil, if needed, and installing dikes,
spillways or other water-control structures to
manage water levels and l ows (U.S. Environ-
mental Protection Agency 2004). Macrophytes
such as
Phragmites
sp. and
Typha
sp. are intro-
duced and allowed to colonize the constructed
site (Scholz and Lee 2005). By and large, wetland
species that spread easily and are tolerant of high
concentrations of nutrients and contaminants are
selected for treatment wetlands. Collectively,
these features attempt to mimic a natural wet-
land's structure and provide the conditions nec-
essary for an efi ciently functioning system.
Figure 13-9.
Tar Creek carries highly polluted mine
runoff from the Treece-Picher-Cardin vicinity, as shown
by its typical rust-orange color at low l ow (see Color
Plate 13-9). According to the U.S. Army Corps of
Engineers, “Tar Creek is highly toxic and, for all intents
and purposes, dead” (USACE 2005); however, continued
stream monitoring has recently revealed the presence
of some i sh and macro-invertebrates. View
downstream just east of Commerce, Oklahoma. Photo
by J.S. Aber.
mental regulations or controls existed. Mining
lead and zinc ore generated a huge volume of
waste rock
-
chat, which was simply dumped on
the surface in big piles (see Fig. 1-15). The chat
piles, water-i lled mines, and former smelting
sites are today sources for highly polluted water
that contains heavy metals. In addition to lead
and zinc, mining byproducts included cadmium,
germanium, and gallium (Park 2005). Streams,
lakes, and shallow aquifers of the region are
severely contaminated (Fig. 13-9).
Such contamination led to the establishment
of Environmental Protection Agency (EPA)
superfund sites in Missouri, Kansas, and Okla-
homa beginning in the early 1980s. After decades
of effort, the former mining areas around Joplin,
Missouri and Galena, Kansas have mostly been
13.7 Contaminated mine-water treatment
Mining brings buried minerals to the surface
where they undergo weathering and may release
acids and toxic compounds into surface and
ground water. The deleterious impacts of mining
on wetlands are well known and well docu-
mented around the world (see chapter 10.3.2).
Wetlands may also be utilized to clean up the
consequences of past mining. The Tri-state
mining district in southwestern Missouri, south-
eastern Kansas, and northeastern Oklahoma was
exploited for lead and zinc beginning in the mid-
1800s until 1970, during which time no environ-
