Characteristics of winds and their effect on dry deposition at the Connecticut coastline of Long Island Sound

Atmospheric concentration samples and meteorological data of onshore and offshore wind classes during 1994 were collected and analyzed to study the directional characteristics of winds and dry deposition of SO42−, NO3−, SO2 and HNO3 at the Connecticut coastline of Long Island Sound. The dry deposition velocities during onshore and offshore winds were approximately equal for all the species. The atmospheric concentrations, however, were higher during onshore than offshore winds throughout the study period for all the measured chemicals. The poor air quality during onshore winds indicated that the industrial complex southwest of the monitoring station was a major source area of the pollutants deposited to the area. Seasonal air quality varied with species, with higher SO42− concentrations and lower SO2 concentrations in summer for both wind classes. The seasonal variation in total dry deposition depended on the time fractions of wind classes. During the warm season, about two thirds of dry deposition were from onshore winds.