Rice fields, pesticide-contaminated

This high agriculture activity compromises the chemical and ecological status of the Ebro delta. Pesticides used in the area migrate into the delta building up, together with the pollution produced by some industries, a contamination that can be dangerous to its both fauna and flora, and this contamination increases when water from the rice fields is drained into the delta [17]. 

Immunochemical methods are rapidly gaining acceptance as analytical techniques for pesticide residue analysis. Unlike most quantitative methods for measuring pesticides, they are simple, rapid, precise, cost effective, and adaptable to laboratory or field situations. The technique centers around the development of an antibody for the pesticide or environmental contaminant of interest. The work hinges on the synthesis of a hapten which contains the functional groups necessary for recognition by the antibody. Once this aspect is complete, immunochemical detection methods may take many forms. The enzyme-linked immunosorbent assay (ELISA) is one form that has been found useful in residue applications. This technique will be illustrated by examples from this laboratory, particularly molinate, a thiocarbamate herbicide used in rice culture. Immunoassay development will be traced from hapten synthesis to validation and field testing of the final assay. 

The second soil, collected at a depth of 0-20 cm from the rice crop fields of the Ebro Delta area (Tarragona, Spain), where the pesticides are currently applied, was naturally contaminated with aged residues corresponding to the last atrazine application carried out 40 days before its sampling. Characteristics of this soil are shown in Table 12.2 (Soil 1), and more details are available in Durand, Forteza, and Barcelo (1989). 

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