Over the past decade it has become apparent that the atmosphere is a significant pathway for the transport of many natural and pollutant materials from the continents to the ocean. The atmospheric input of many of these species can have an impact (either positive or negative) on biological processes in the sea and on marine chemical cycling. For example, there is now evidence that the atmosphere may be an important transport path for such essential nutrients as iron and nitrogen in some regions. In this report we assess current data in this area, develop global scale estimates of the atmospheric fluxes of trace elements, mineral aerosol, nitrogen species, and synthetic organic compounds to the ocean; and compare the atmospheric input rates of these substances to their input via rivers. Trace elements considered were Pb, Cd, Zn, Cu, Ni, As, Hg, Sn, Al, Fe, Si, and P. Oxidized and reduced forms of nitrogen were considered, including nitrate and ammonium ions and the gaseous species NO, NO2, HNO3, and NH3. Synthetic organic compounds considered included polychlorinated biphenyls (PCBs), hexachlorocyclohexanes (HCHs), DDTs, chlordane, dieldrin, and hexachlorobenzenes (HCBs). Making this assessment was difficult because there are very few actual measurements of deposition rates of these substances to the ocean. However, there are considerably more data on the atmospheric concentrations of these species in aerosol and gaseous form. Mean concentration data for 10° × 10° ocean areas were determined from the available concentration data or from extrapolation of these data into other regions. These concentration distributions were then combined with appropriate exchange coefficients and precipitation fields to obtain the global wet and dry deposition fluxes. Careful consideration was given to atmospheric transport processes as well as to removal mechanisms and the physical and physicochemical properties of aerosols and gases. Only annual values were calculated. On a global scale atmospheric inputs are generally equal to or greater than riverine inputs, and for most species atmospheric input to the ocean is significantly greater in the northern hemisphere than in the southern hemisphere. For dissolved trace metals in seawater, global atmospheric input dominates riverine input for Pb, Cd, and Zn, and the two transport paths are roughly equal for Cu, Ni, As, and Fe. Fluxes and basin-wide deposition of trace metals are generally a factor of 5-10 higher in the North Atlantic and North Pacific regions than in the South Atlantic and South Pacific. Global input of oxidized and reduced nitrogen species are roughly equal to each other, although the major fraction of oxidized nitrogen enters the ocean in the northern hemisphere, primarily as a result of pollution sources. Reduced nitrogen species are much more uniformly distributed, suggesting that the ocean itself may be a significant source. The global atmospheric input of such synthetic organic species as HCH,PCBs, DDT, and HCB completely dominates their input via rivers.

The atmospheric input of trace species to the world ocean

An absorption model of GAS/Particle partitioning of organic compounds in the atmosphere

PAH source fingerprints for coke ovens, diesel and, gasoline engines, highway tunnels, and wood combustion emissions

Measuring and simulating particulate organics in the atmosphere: problems and prospects

An absorption model of the gas/aerosol partitioning involved in the formation of secondary organic aerosol

Three- to six-ring polycyclic aromatic hydrocarbons in the vapor phase (PAHs/sub vap/) and in the particulate phase (PAHs/sub pat) and total suspended particulate (TSP) in ambient air were sampled and determined year-round. At ambient temperature levels, substantial amounts of three-to five-ring PAHs were found in the vapor phase depending upon temperature (T, K) and the six-ring PAHs were all found in the particulate phase. For three- to five-ring PAHs, the Langmuir adsorption concept was introduced for PAHs/sub vap/ and PAHs/sub pat/ on the particulates. log ((PAHs/sub vap/) /)(PAHs/sub pat/) / (TSP))) was related to 1/T, and a high correlation (r = 0.834 to -0.942) was obtained between the two quantities. Thus, aspects of the three- to five-ring PAHs in ambient air were considered to be explained by using the Langmuir adsorption concept.

Kazuhiro. Kuwata

Papers

Effects of ambient temperature on aspects of airborne polycyclic aromatic hydrocarbons

Collection of atmospheric polycyclic aromatic hydrocarbons using polyurethane foam plugs.