SPECULATIONS ON BUDGET OF PARTICULATE AND VAPOR-PHASE NON-METHANE ORGANIC-CARBON IN GLOBAL TROPOSPHERE

Perhaps less is known about the global source, distribution, and fluxes of non-methane organic matter than any other major class of chemical substances in the atmosphere. Source strength estimates and consideration of the available concentration data suggest that the quantity of organic carbon on large particles (d>1 μm) in the global troposphere can be explained by primary emissions from anthropogenic sources and such natural sources as the ocean, crustal weathering, and forest wildfires. However, these pollution and natural sources apparently cannot account for the global tropospheric burden of small particle (d<1 μm) organic carbon. Approximately 80-160 MT/yr of small particle carbon from some additional source is required to balance this cycle. Possibilities include direct production from the leaves of vegetation and gas to particle conversion of natural and anthropogenic organic carbon compounds. The estimated production of reactive vapor phase organic compounds from natural and pollution sources is sufficient to account for the mass of this additional small particle organic carbon. However, considerably more data is required on the global distribution, source strengths, reaction pathways and rates, and removal mechanisms before an accurate description of the non-methane organic carbon cycle can be made. © 1978 Birkhäuser Verlag.