Subject: Biogeochemical Cycling of Mercury In The North Atlantic Ocean This research will investigate the speciation, distribution and biogeochemical cycling of Hg in the North Atlantic Ocean. The ocean is an important source and sink for atmospheric Hg, and plays a significant role in the global Hg cycle. Knowledge of the behavior and fate of Hg in the marine environment is hindered by the lack of information on the distribution and speciation of Hg in open ocean regions. The Intergovernment Oceanographic Commission (IOC) Baseline Trace Metal cruise aboard the C.S.S. Hudson in June/July 1993 will provide essential data, as well as the supporting chemical and physical oceanographic program, to complement and extend previous oceanic studies of Hg, particularly those in the productive equatorial Pacific Ocean. Shipboard analyses will be made for reactive Hg, and dissolved gaseous species (Hg degree and dimethylHg). Post cruise analyses will be conducted for total Hg, participate Hg, and for monomethylHg. The research will focus on the distribution of methylated Hg species and elemental Hg in an effort to ascertain the principal sources and sinks for these compounds in the surface and deep ocean. The data obtained will allow the testing of current hypotheses concerning the sources and fate of Hg species in open ocean waters, and will broaden the understanding of the role of the ocean in the global Hg cycle.
