Estimation of Emissions of [gamma]-Hexachlorcyclohexane from the Great Lakes-St. Lawrence Ecosystem Using a Coupled Efficient Kalman Filter-Atmospheric Transport-Soil Model

In this study, results of [gamma]-HCH emissions from the Great Lakes-St. Lawrence ecosystem, estimated from the coupled model, are presented and discussed. A source receptor technique is used to identify a priori the locations of emission sources of [gamma]-HCH, the emissions are then updated through a Kalman filtering procedure which minimizes the weighted difference between the predicted mixing ratios from the coupled model and the measured concentrations over the Great Lakes-St. Lawrence river region. Results from the inverse technique for the year 1995 have been compared with grided [gamma]-HCH emission inventory in Canada. It is shown that the estimated emissions of [gamma]-HCH are consistent with the measured emissions. It is found that the St. Lawrence valley has larger emissions of [gamma]-HCH than the Great Lakes region, indicating an opposite distribution to the emission usage inventory, but in agreement with the measured [gamma]-HCH concentration.