Pesticides Research, 86 – Fate of Pyrethroids in Farmland Ponds

Fate of Pyrethroids in Farmland Ponds

PART II : Fate of pyrethroids in farmland ponds. Experimental data interpretation using mathematical models

8 Introduction, part II

Many pesticides, especially insecticides, are very toxic to aquatic life. During application of pesticides they may accidentally reach streams and ponds e.g. by wind drift. To assess potential harm from pesticides to aquatic organisms in farmland ponds it is essential to know the fate of the pesticides in such ponds.

Pyrethroid insecticides have been used widespread in Danish agriculture and they are very toxic to fish, crustacean and aquatic insects. For risk assessment it is therefore important to know how these compounds partition in an aquatic ecosystem and residence time in different parts of the system.

The aim of this study is to investigate the fate of pyrethroid insecticides in small farmland ponds after the pesticides have been applied to the surface of the pond. This includes distribution in the pond, disappearance and bioavailability.

An ecosystem is a complex system built up by biotic and non biotic elements. To model a system it is necessary to divide it into compartments. This distribution model should include all compartments that are important either because they contribute significantly to the mass balance and/or because they are important as residence for sensitive aquatic organisms.

The investigation is reported in two parts. The first part includes field studies while the second part focuses on the distribution model. This part of the report concerns the distribution model in form of a mathematically fate model to interpretation of the experimental results using artificial farmland ponds. For a more detailed description of the experimental conditions part I should be consulted. The scope of this investigation is not to "develop a model", but to make an extended interpretation of the experimental results by using mathematical models.