Long-term measurements of gamma-HCH in precipitation in the Netherlands

The results of 20 years of measuring gamma-HCH in precipitation in the Netherlands are presented here. Analysis has revealed a systematic seasonal behaviour, with enhanced levels of gamma-HCH in precipitation from April through June. Evidence was found for a statistically significant change in concentrations during the last 20 years. Measurement results from the last three years (1999-2001) showed a clear downward trend, suggesting a decline in lindane emissions. An evaluation of measurement results from north-west Europe confirms the large-scale distribution of gamma-HCH in precipitation in north-west Europe. Given the large uncertainties in emission estimates and in modelling of atmospheric transport and deposition, measurements are concluded to form a better tool for monitoring the changes in environmental quality and emissions.