Preface, Danish Environmental Protection Agency

Pesticides in air and in precipitation and effects on plant communities

Preface

The admission of pesticides on plants, water and soil surfaces may come from either direct application or unintentionally through spillage, run off and dry or wet deposition. Increasing efforts has been made to protect against the unintended pollution of the aquatic and terrestrial environments. The present project was started in 1996 as a co-ordinated research initiative to elucidate pesticide distribution via the atmosphere and consequences to plant life.

To cover this broad range of information, the project consisted of four parts to cover both emissions to the atmosphere, modelling of spreading in the atmosphere, deposition in precipitation and effects on plants. The participating institutes were The Danish Technological Institute (Laboratory system to determine pesticide volatility), National Environmental Research Institute (Modelling of atmospheric transport and deposition) and Danish Institute of Agricultural Sciences (Analysis of pesticides in precipitation and Effects of herbicides in precipitation on plants). The project was supported by The National Environmental Protection Agency (Miljøstyrelsen).

Besides the expected finding of pesticides in use in Denmark in the precipitation, an unexpected experience from the project was the finding of high concentrations of the herbicide DNOC in precipitation. This compound has not been used in Denmark since the end of the eighties. DNOC appeared in rainwater all over the sampling period, and it was concluded, that DNOC hardly came from pesticide use, but was due to photochemical reactions with toluene and nitrogen oxides in the atmosphere. The concentrations of DNOC were much higher than for the other pesticides and probably also a number of other chemicals are deposited on plants from the atmosphere.

Information gathered in such broad co-operative projects are of great importance for the elucidation of the spreading of pesticides and to calculate the load of pesticides on agricultural and non-agricultural areas. Further these values are important for the evaluation of pesticides in relation to their registration.

The current interest of the project was shown by an inquiry from members of parliament about spreading of pesticides to Denmark from other European countries and by the need for a technical report on causes of DNOC-pollution in the atmosphere.

A management group for the project was established with participants from University of Odense (Christian Lohse) and The National Environmental Protection Agency (Inge Vibeke Hansen). Chairman of the Management group was Erik Kirknel (DIAS), who also took the initiative to the project. The management of the project was taken over by Arne Helweg in 1998.