Environmental Engineering Reference
In-Depth Information
its seasonal application. It is more frequent and concentrated during late spring and early
summer months, following the spring application, and diminishes significantly in fall and
winter (Pereira and Hostettler 1993; Bradford et al. 2010). For instance, it was determined
that almost 80% of the annual herbicide load to the Gulf of Mexico occurred during the
growing season, that is, from May to August (Clark and Goolsby 2000).
Although agricultural pesticide inputs are dominant, it was shown that pesticide contri-
butions from urban sources to water contamination should not be neglected, sometimes
being similar to that of agriculture, especially on a local scale (Bucheli et al. 1998; Kolpin
et al. 1998; Blanchoud et al. 2007; Wittmer et al. 2010). There are a number of nonagricultural
pesticide sources, originating from urban pesticide use and nonapproved pesticide use or
misuse. Pesticides are commonly used in landscaping, gardening, food distribution, and
home pest control (Manahan 2001). Outdoor herbicides account for about 85% of pesticides
used in urban areas (Braman et al. 1997). They are prone to be flushed into the sewage dur-
ing rainfall. It was shown that effluents from urban wastewater treatment plants (WWTPs)
contribute to a great extent to herbicide pollution of surface water (Nitschke and Schüssler
1998; Kolpin et al. 2006). Farmyard activities, such as pesticide spillage, tank and sprayer fill-
ing, use of faulty equipment, washing or waste disposal, etc., can also significantly contrib-
ute to pesticide loading to surface water and groundwater. It was estimated that farmyard
activities can cause less than 20% of pesticide load into surface waters, originating from
WWTPs or direct input of pesticides into surface waters (Gerecke et al. 2002; Neumann
et al. 2002; Leu et al. 2004a). Many pesticides are not significantly eliminated in WWTPs
(Nitschke et al. 1999), and therefore their residues end up in natural waters after WWTP
effluents are discharged. Pollution can be reduced by good agricultural practices and the
installation of systems for farmyard wastewater decontamination, which can provide a
decontamination level greater than 90% (Fait et al. 2007). In urban areas, some pesticides
are used for the protection of construction materials. They are added to outdoor building
materials to prevent biological deterioration. For instance, the herbicide mecoprop is used
as a protection agent in flat-roof sealing. It was determined that mecoprop loads from flat
roofs enter surface waters up to 65% through WWTP effluents (Bucheli et al. 1998; Gerecke
et al. 2002). Another nonagricultural source of pesticides is their use in the maintenance of
the golf courses. Artificially created wetlands on a golf course have the potential for accept-
ing and storing pesticide-polluted water from within the golf course (Kohler et al. 2004).
Pesticide pollution of surface water and groundwater can arise from point (localized) and
nonpoint (diffuse) sources (Carter 2000; Gerecke et al. 2002; Holvoet et al. 2007). In agri-
cultural areas, there are two main sources of pesticide losses to surface waters: farmyards
acting as point sources and agricultural fields acting as diffuse sources (Müller et al. 2002;
Leu et al. 2004a). Point sources of pollution are largely the result of pesticide-handling pro-
cedures, such as spills during filling of the spraying equipment, cleaning of the equipment,
usage of faulty equipment, processing of spray waste, etc. Several studies have shown that
the major risk of point source pollution is a poor operator handling within the farmyard
area where sprayers are filled (Kreuger 1998; Müller et al. 2002; Neumann et al. 2002; Fait
et al. 2007). Water contamination can be caused by accidental pesticide spillage as well as
inadequate pesticide storage and disposal (Ricking and Schwarzbauer 2008; Frische et al.
2010). Sometimes, pesticide waste originating from agricultural or industrial activities can be
approved for discharge into surface waters (Carter 2000). It was determined that for contami-
nation of surface waters, WWTPs (for the treatment of farmyard and urban wastewater) are
the most important point source of pesticides, constituting 20%-90% of the total pesticide
water pollution in different catchments, especially during dry weather periods (Kreuger
1998; Müller et al. 2002; Neumann et al. 2002, 2003; Leu et al. 2004a; Holvoet et al. 2005).
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