Herbicide groundwater contaminated

Abiotic hydrolysis, sorbed pesticides, 221-43 Acetanilide herbicide, groundwater contamination, 299 Acid-catalyzed hydrolysis aldlcarb by RIEX, 257f kinetics, disappearance rate, 223 Acid hydrolysis, sorbed pesticides, 242... 

Biocides should not be present in water used for aquaculture. Sources of herbicides and pesticides are mnoff from agricultural land, contamination of the water table, and spray drift from crop-dusting activity. Excessive levels of phosphoms and nitrogen may occur where mnoff from fertilized land enters an aquaculture faciUty either from surface mnoff or groundwater contamination. Trace metal levels should be low as indicated in Tables 4 and 5. 

ISOTEC is a technology that uses the periodic injection of hydrogen peroxide and proprietary catalysts to oxidize organic contaminants in situ. According to the vendor, this technology can treat soil and groundwater contaminated with chlorinated compounds, petroleum hydrocarbons, polychlorinated biphenyls (PCBs), trichloroethene (TCE), tetrachloroethene (PCE), pesticides, herbicides, as well as benzene, toluene, ethylbenzene, and xylene (BTEX). The ISOTEC technology is commercially available. 

Pickett, C.H., L.S. Hawkins, J.E. Pehrson, and N.V. O Connell (1992). Irrigation practices, herbicide use and groundwater contamination in citrus production A case study in California. Agri., Ecosyst. Environ., 41 1-17. 

Ripparbelli, C. Scalvini, C., Bersani, M., Auteri. D., Azimonti, G., Maroni, M., Salamana, M.,Carreri, V., 1996 Groundwater contamination from herbicides in the region of Lombardy - Italy., Period 1983-1993., Proceedings of the X symposium Pesticide chemistry, Piacenza, 559-63. 

Properties of Herbicides, Indicating Their High Groundwater Contamination Potential... 

Table 26.1 summarizes the properties of herbicides and their high groundwater contamination potential. ... 

Guideline values proposed by the World Health Organization based on a toxicological approach for each substance are 2 /rg/l for simazine and atrazine, and 20 /rg/l for alachlor. Directive 91/414/CE harmonizes at the European scale the principle of authorization delivery of active substances. For example, a herbicide can be introduced in the positive list of the directive Annex 1 if only the scenario takes into account toxicity, ecotoxicity, and study on presence and fate in the environment, in order to exclude aU risks of groundwater contamination at levels higher than... 

Among the triazine herbicides, atrazine has been classified as a restricted use pesticide (RUP) because of its potential for groundwater contamination. Only the certified applicators may purchase and use this compound. 

Cyclodextrins have found particular application for the formulation of poorly water soluble, volatile, or unstable herbicides. Among the advantages of cyclodextrin complexes of pesticides are enhanced stabilization, reduced volatility, masked bad odor, enhanced wettability, solubility and bioavailability, and controlled release properties. Of the cyclodextrins, BCD is the only one available at a reasonid)le price, and its use may be economically feasible within a few years (. Several herbicides that have been frequently implicated in groundwater contamination (1-2) were selected as candidates for complexation with BCD in an attempt to develop formulations that could prevent entry of the chemical into the groundwater while maintaining effective weed control. 

An interesting example on the question of by-products is provided by the surface and groundwater contamination by pesticides. Triazines are among the most abvmdant pesticides and since 1997, atrazine has been found in more than 50% of samples of both surface water and groundwater, while its degradation product, desethylatrazine, is the most frequently found (about half of all analyses). Other frequently found herbicides include diuron and isoproturon (urea substitute... 

Cobalt and nickel porphyrins have also been used for catalyzing the chemical dechlorination with a reductant, namely titanium(III) citrate or nanoscale Zero Valent Iron (nZVI), of e.g. atrazine, (2-chloro-4-(ethylamine)-6-(isopropylamine)-s-triazine), a widely used herbicide which is a persistent groundwater contaminant [38]. Nickel 5,10,15,20-tetrakis(l -methyl-4-pyridinium)porphyrintetra(p-toluene-sulfonate) (TMPyP) was activated by nZVI, while cobalt porphyrins (TMPyP,5,10,15,20-tetrakis(4-hydroxyphenyl)-21 H,23H-porphine-(TP(OH)P) and 4,4, 4",4 -(porphine-5,10,15,20-tetrayl)tetrakis (benzenesulfonic acid)-(TBSP)) were activated by titanium(lll) citrate as the electron donor. All these processes probably could be more efficient using electrochemical methods. 

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. 

Baird is the 20-acre site of a former chemical mixing and batching company. Poor waste disposal practices resulted in the contamination of groundwater, soil, the municipal water supply, and a brook adjacent to the site. Over one hundred contaminants, including chlorinated and nonchlorinated volatile organics, heavy metals, pesticides, herbicides, and dioxins, had been identified in site soil and groundwater. Remediation activities included soil excavation and incineration, and groundwater treatment (the audit focused on the soil excavation and incineration... 

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