Transport patterns and potential sources of total gaseous mercury measured in Canadian high Arctic in 1995

Trajectory cluster analysis and the potential source contribution function (PSCF) model have been used to investigate the source–receptor relationship for the total gaseous mercury (TGM) measured in the Canadian High Arctic (Alert, 82.5°N, 62.3°W) during 1995. Cluster analysis of 10-day back-trajectories in 1995 shows that the synoptic flows arriving at Alert are dominated by the air masses from the north. Long-range transport only occurs in the cold seasons while summertime flows tend to circulate in the Arctic Ocean. The potential source regions identified by the PSCF modeling include Eurasia and populated areas in the North America and Europe. Based on the modeling results, it is suggested that the elevated TGM concentrations found in the Arctic summer should be of geological origins, mainly from the evasion of volatile Hg0 from earthʹs surfaces. In the autumn and winter, mercury is transported to the receptor site from remote anthropogenic sources. The preferred sources of TGM in the spring cannot be clearly determined due to the Arctic springtime mercury depletion, which significantly reduces the number of trajectories contributing to PSCF values. Using TGM data of higher temporal resolution improves the sensitivity of the PSCF modeling results.