Surface waters herbicide contamination

A comprehensive search (295) of the STORET water quaUty database, maintained by the U.S. EPA Office of Water, is used to evaluate the potential water quaUty implications of various herbicides. This database contains information on contamination of surface water (SW) and groundwater (GW) suppUes. The data are provided to give a general impression of the occurrence of a given herbicide in SW and GW (269). The U.S. EPA scheme for categorizing a chemical s carcinogenic potential is used for herbicides for which healthy advisory information (HA) is available. The U.S. EPA is continually issuing HAs for various environmental contaminants HAs available in Reference 269 were used in preparation of this article. 

Dinitroaniline herbicides have low soil mobility potential. Herbicide residues in the treated field are usually incorporated into the upper layers of the soil mainly as unextractable bound residue therefore, the movement of dinitroaniline herbicides from soil to the water compartment is minimal. Run-off is the principal route, which could lead to the contamination of surface waters. Residue methods were developed to measure the parent concentration in water samples. 

Bucheli, T. D., S. R. Mttller, A. Voegelin, and R. P. Schwarzenbach, Bituminous roof sealing membranes as major source of the herbicide (R,S)-mecoprop in roof runoff waters Potential contamination of groundwater and surface waters , Environ. Sci. Technol., 32, 3465-3471 (1998b). 

Mills, M.S. and E.M. Thurman (1994a). Reduction of nonpoint source contamination of surface water and groundwater by starch encapsulation of herbicides. Environ. Sci. Technol., 28 73-79. 

The widespread application of herbicides in agriculture has resulted in many polluted surface waters. As a result, numerous pesticides/herbicides have been treated in bench-scale laboratory studies with 03/UV/H202 processes during the last 10 years (see Table 10). Among them, many studies focused on the treatment of atrazine and other. v-triazine herbicides (simazine, prop-azine, etc.). Atrazine is a priority pollutant that similar to other individual pesticides has a very low maximum contaminant level (MCL) (0.1 pg L 1 for the European Environmental Commission according to Directive 80/778/ EEC). In some countries atrazine cannot be used but it is still found in many surface waters. In France, for example, atrazine was banned on September 28, 2001. From applied technologies, only carbon adsorption [180] and possibly advanced oxidations can be recommended to remove some of these... 

Often, the rates of fertilization in intensively managed agriculture are intended to satiate the needs of crop plants for these chemicals, so their productivity will not be limited by nutrient availability. However, excessive rates of fertilization have important environmental costs. These include the contamination of ground water with nitrate eutrophication of surface waters caused by nutrient inputs (especially phosphate) acidification of soil because of the nitrification of ammonium to nitrate large emissions of nitrous oxide and other nitrogen gases to the atmosphere, with implications for acid rain and Earth s greenhouse effect and the need to use herbicides to control the weeds that flourish under artificially nutrient-rich conditions. 

An herbicide, atrazine, which is commonly used on corn crops in the mid-western United States, was chosen as an example. During the spring, rainfall washes this compound from soil, and concentrations of herbicide in surface water will reach the Environmental Protection Agency s annual maximum contaminant level of 3 gg/L. It is necessary to detect this compound at concentrations as low as 0.05 gg/L. How would one isolate and purify this compound from water for analysis by gas chromatography/mass spectrometry (GC/MS) using SPE Some questions and ideas that come to mind follow ... 

Butoxyethanol was detected at a concentration of 23 g/L in a surface water sample collected in 1979 at a site in Kentucky where it has been estimated that as many as 100,000 drums of industrial waste were disposed of between 1967 and 1977 (Stonebreaker and Smith 1980). Examination of mass spectral libraries of data from water and soil samples from U.S. hazardous wasted sites taken between late 1987 and mid-1989 identified 2-butoxyethanol in 110 samples (Eckel et al. 1996). The media in which the compound was found was not indicated. No other data were found in the available literature on the levels of 2-butoxyethanol or 2-butoxyethanol acetate in surface or groundwater, or in soil or sediment such data would be useful to assess the potential for exposure from these media. The low estimated BCF and values of 2-butoxyethanol and 2-butoxyethanol acetate (see Section 5.3.1 and Tables 3-3 and 3-4), and the ease with which these compounds are metabolized in higher trophic level animals (see Section 2.3) indicate that these compounds will not biomagnify in the food chain and, consequently, that concentrations in food will be insignificant however, there may be some potential for food contamination from packaging and washing procedures (see Section 5.4.4). The minor use of 2-butoxyethanol in herbicides (see Section 4.3) may also present the potential for food contamination by this compound. 

A disadvantage of a weed wiper is that when a treatment is complete there can be a large area of the wiper still contaminated with herbicide. This has to be hosed off with water, using a brush to ensure penetration of the absorbent surface. It is important to ensure that the herbicide contaminated washings can be disposed of safely and, when dry, the wiper should be covered by a protective sleeve. 

The insect repellent N,N-diethyltoluamide (DEET) and the herbicide mecoprop (MCPP) were also identified in the samples SW1, SW2 and LW. The amounts of DEET ranged between 200 and 320 pg/L. Similar concentrations in all samples suggest that DEET is moderately stable under anaerobic and aerobic conditions. DEET and MCPP are widely used and the resulting contamination of surface water has been reported (e.g. Franke et al., 1995 Buser et al., 1998). The herbicide has also been reported as contaminant in landfill leachates with a high persistence under the anaerobic conditions existing within the deposits (e.g. Schultz und Kjeldsen, 1986 Gintautas et al., 1992). 

The commonest of these occur in industrialized and urban areas where discharges from indnstry canse the snrface water (and groundwater to a lesser extent) to be contaminated with phenol or its derivatives, like cresol. Examples include the manufacture of certain herbicides or their precursors, the pulp and paper industry, the manufacture of phenol for use in plastics, such as phenol-formaldehyde, the manufacture and use of pentachlorophenol as a wood preservative, use of phenol derivatives (cresol, etc.) in hospitals, etc. The runoff of these compounds to surface waters and seepage to the groundwater are enlarged in rainy seasons in many Asian cities. 

EXPOSURE ROUTES Inhalation (plant emissions and herbicide) absorption through skin and eyes (farm workers) ingestion (contaminated fish, agricultural products and agricultural runoff in surface water). 

TJicloram (4-amino-3,5,6-trichloropicolinic acid) is a herbicide used mainly to control woody plants and herbaceous weeds. This chemical is used to improve grassland or to maintain watershed and could contaminate surface water. Upon entering surface water, photochemical or microbiological processes are the most likely routes for picloram degradation. 

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