An equatorial pacific ocean source of atmospheric mercury.

Pronounced increases in total gaseous mercury (TGM) in the near surface marine atmosphere were found in the equatorial region (4 degrees N to 10 degrees S) of the Pacific Ocean at 160 degrees W. The atmospheric enhancement of TGM corresponded closely to sea-surface manifestations of equatorial upwelling as reflected in measured changes of temperature and nutrient concentrations as well as to variations of reactive mercury in surface seawater. The elevated atmospheric TGM levels most probably result from oceanic mercury evasion associated with upwelling and increased biological production that occurs in the equatorial Pacific Ocean.This evidence of sea-to-air mercury transfer supports model predictions of an oceanic source of atmospheric mercury and suggests that marine-derived mercury emissions should occur in other biologically productive regimes.