Investigation of total gaseous mercury in the atmosphere of the Great Lakes and St. Lawrence River basin.

摘要

Mercury (Hg) is a highly toxic pollutant, and it can undergo long-range transport in the atmosphere. Hg is a pollutant of concern because of its tendency to accumulate and concentrate in biota. In this study, a statistical analysis of total gaseous mercury (TGM) was carried out using seven years of measurements at three Canadian Atmospheric Mercury Measurement Network (CAMNet) sites in the Great Lakes basin and three years measurements at two CAMNet sites in the St. Lawrence River basin. The average TGM concentrations ranged from 1.59 +/- 0.24 to 1.84 +/- 0.39 ng m-3 at the five sites. Two of the sites, Point Petre and St. Anicet, have significantly higher (p 0.05) TGM concentrations in the Great Lake basin and St. Lawrence River basin, respectively. Large Hg evasion from Lake Ontario is a primary contributor for Point Petre, while nearby industrial and metropolitan areas may contribute more anthropogenic inputs to St. Anicet. Seasonal variability was detected at all five sites with a similar winter high pattern. Higher TGM concentrations were observed at Point Petre in summer, whereas lower TGM values were observed during summertime at the other four sites. In terms of diurnal pattern, minimum TGM concentrations occur before early morning and reach maximum near noon at most sites except for St. Anicet with night peak. The diurnal pattern in summer is more prominent than in other seasons. (Abstract shortened by UMI.)