at b. Low Temperature Emissions from Forests and Agricultural Areas Individual groups will. collect atmospheric samples from forests, agricultural regions, etc. for analysis of organic substances and vapor phase metals, the latter by laser spectroscopy. ¥V. THE FIRST TWO YEARS OF SEAREX A. Flux Experiments 1. Objectives The objectives of the flux experiments are to give us quantita- tive information on the input of heavy metals and certain organic substances to the ocean from the atmosphere. a. Heavy Metals Heavy metals are a normal constituent of unpolluted air, and it is often not a simple matter, particularly in remote regions, to distinguish between natural and anthropogenic sources of these elements. A first approach to this problem has been to calculate enrichment factors using reference elements from expected sources such as the ocean or the earth's crust. This approach has identified, in several remote regions, the elements Pb, Cd, Zn, Se, Sb, As, Cu, Hg and Ag (Duce et al., 1976a) as having concentrations higher than normally expected from simple crustal weathering or bulk seawater injection into the atmosphere. Thus these metals are of primary interest, both because their high concentrations may be related to anthro- a F pogenic processes and because they may be related to natural geochemical pro- i cesses which we do not yet fully understand. 4 An estimation of the input to the ocean of these metals, and the clearly crustal origin elements as well, is critical to an understanding of the basic geochemical and environmental 5 wd eine e- SA s z 4m. att we oe [ant ‘ nd aa re