Environmental Engineering Reference
In-Depth Information
The U.S. Soil Conservation Service (1993) developed a wetland process for treatment
of agricultural runoff consisting of a wet meadow, followed by a marsh and pond with
an optional vegetated polishing area. It is applicable for the removal of sediments and
nutrients such as phosphorus. The wet meadow with a slope of 0.5% to 5% consists of
permeable soils with cool-season grasses. The depth of the marsh with cattails var-
ies from zero at the surface of the meadow to 0.46 m at the deep pond. The deep pond
performs as a biological ilter for the removal of nutrients and sediments. Fish, such as
common or golden shiners, should be included in the pond to feed on the plankton.
Average sediment and phosphorus removal in a system for potato growing in northern
Maine over two seasons were determined to be 96% and 87%, respectively (Higgens et
al., 1993).
Losses to the environment of pesticides and herbicides through volatilization and runoff
must also be minimized. Large quantities of agrochemicals have been found in various
water bodies such as the Great Lakes in North America. Application of these chemicals
during calm conditions can minimize losses due to drift. Biological methods can be used
to control weeds and insects.
It has been proposed that an “integrated pest management” (Janzen, 1998) strategy be
utilized through chemical, biological, and cultural methods to optimize the use of pesti-
cides. The EPA (2012) indicates that four steps are included: (1) action thresholds are set,
(2) pests are monitored and identiied, (3) pests are prevented from becoming a threat, and
inally, (4) pests are controlled when other means fail.
6.5.1.5 Source Control
A major element in
source control
is reduction in use of various mineral and organic fertil-
izers and pesticides. These are sources for non-point contaminant stressors when they are
transported in the ground. Other source control measures that can be exercised include
• Strict standards and monitoring to maintain ground and surface water quality,
and storage systems commonly used in industrial processes—to reduce source
contaminants
• Optimization of natural pollinators and predators to conserve species and eco-
systems by maintaining natural vegetation near agricultural lands (Thies and
Tscharntke, 1999)
• Optimization of the water supply and quantity by correct use of water and chemi-
cals to protect human health and ecosystems (Matson et al., 1997)
• Use of technologies that reduce erosion, salinization, water consumption, chemi-
cal pollution, and other environmental effects
• Minimization of tillage to prevent runoff
• Use of intercropping and ground cover as, for example, inter-planting with red clo-
ver to reduce water runoff, Wall et al. (1991)—with resultant beneits of (a) reduc-
ing water and soil loss, (b) conservation of water, (c) decreasing non-point sources
of pollution, and (d) increasing water availability for plants (NGS, 1995)
• Minimization of water use through precise applications, e.g., through night appli-
cation, use of surge-low irrigation, low-pressure sprinklers, and drip irrigation
(Verplancke, 1992; Goldhamer and Snyder, 1989)
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