Relación entre las características pluviométricas y los niveles de residuos de insecticidas organoclorados en un curso fluvial

The concentrations of organochlorine insecticide residues was investigated during four well defined periods in samples of water from the River Almar (province of Salamanca, Spain). These periods coincides with a phase of drought, gentle rain after the drought, strong rains after the drought and heavy rains. It is seen that solubilization and drag from de basin are very small during the dry phase, increase during the phase of heavy rains, continue to rise during the gentle post-drought phase and reach a maximum during the strong rains post-drought. Among the organochlorine pesticides, lindane was always outstanding in its behaviour; this is noteworthy in that it is the only pesticide whose use is permitted by Spanish legislation.