Pesticide Degradation in Water - Pesticides: Evaluation of Environmental Pollution - page 79

4
Pesticide Degradation in Water
Pilar Sandín-España and Beatriz Sevilla-Morán
CONTENTS
4.1 Routes for Pesticides and Transformation Products to Reach Aquatic
Environment ...................................................................................................................... 79
4.2 Pesticide Degradation in the Water Compartment ......................................................... 83
4.3 Environmental Relevance of Transformation Products ................................................. 87
4.3.1 Properties Affecting the Fate of Transformation Products................................ 87
4.3.2 Biological Activity of Transformation Products.................................................. 89
4.4 Legislative Framework of Pesticide Residues in Water .................................................. 92
4.4.1 European Union Water Legislation....................................................................... 92
4.4.2 Other International Legislation ............................................................................. 94
4.5 Occurrence of Transformation Products in Environmental Waters............................. 95
4.6 Chemical Analysis of Pesticide Degradation Products ................................................ 113
4.7 Future Trends ..................................................................................................................... 117
Acknowledgments ...................................................................................................................... 119
References..................................................................................................................................... 119
4.1 Routes for Pesticides and Transformation
Products to Reach Aquatic Environment
Since many years, intensive agriculture has led to a large-scale use of herbicides, fungi-
cides, and insecticides in developed countries. As a result, some of these pesticides, which
are widely used in rural areas for agricultural purposes, constitute important pollutants
of natural water. In this sense, environmental contamination of natural water by pesticide
residues has been a great concern since 1940 (Coats 1993). Freshwater is considered the
most precious of all natural resources. Furthermore, groundwater is the main source of
drinking water in many European countries and in the United States (D'Archivio et al.
2007). In rural areas, groundwater is often the only source of water with acceptable quality
for human consumption without any treatment.
During the last 30-40 years, there has been a general trend toward the introduction
of agrochemicals with lower application rates, decreased environmental persistence, and
reduced nontarget organism toxicity. For example, whereas the average rate of use for
chlorinated hydrocarbon insecticides was estimated at 3 Kg/ha, more recently introduced
pyrethroid or neonicotinoid insecticides may be applied at 0.01-0.1 Kg/ha (Casida and
Quistad 1998). Similar trends exist for herbicides also, the use of which, for many crops,
has shifted from Kg/ha in the 1950s to g/ha by the 1990s, with herbicides belonging to
families such as sulfonylurea and cyclohexanedione oxime.
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