SEAREX OVERVIEW (INCLUDING DETAILS OF MAJOR JOINT FIELD EXPERIMENTS) I. INTRODUCTION There has been increasing interest in the possibility that significant An understanding of the importance of the atmosphere as a transport path is critical in determining the basic geochemical cycles and budgets of a variety of naturally occurring substances and in predicting the near-global impact of anthropogenic material in open ocean regions. In coastal areas primary attention has been given to direct water discharge of river and of urban and industrial wastes, although atmospheric input may also be large and in some cases dominant for certain substances. For example, the input of several trace metals to Lake Michigan appears to be primarily from air pollution fallout from Chicago (Skibin et al., 1973). Patterson and Settle (1974) found that the atmospheric deposition of Pb into . a 12000 Km? area of the Southern California Bight accounted for about 45% of the pollutant Pb input, the remaining 55% being from waste water, storm runoff, and river input. There is evidence that measurable quantities of lead and perhaps other trace metals, DDT, PCB, low molecular weight petroleum hydrocarbons and other organic substances are transported to the open ocean by the atmosphere, either as particles or in the gas phase (SCEP, 1970; FAO, 1971; Duce et al., 1976a; Fitzgerald, 1976; Bidleman et al., 1976). The high lead content of Greenland ice has been attributed to the burning of tetraethy] lead in auto- vr ee t to the ocean via the atmosphere in mid-ocean regions. e arene quantities of both natural and anthropogenic substances may be transported