Atmospheric 14CO2 variations in the equatorial region

Abstract

Results of 14CO2 monitoring at two sampling sites in the equatorial region of the South American continent (Aychapicho, Ecuador and Llano del Hato, Venezuela) are presented. Data for two other stations representing undisturbed marine atmosphere at mid-latitudes of both hemispheres, far from large continental sources and sinks of CO2 (Izana, Tenerife, Spain and Cape Grim, Tasmania). Between 1991 and 1993, 14CO2 levels in the tropical troposphere were generally higher by 2-5 ‰ when compared to mid-latitudes of both hemispheres. This apparent maximum of 14C in the tropics can be explained by two major factors: emissions of 14C-free fossil fuel CO2, restricted mainly to mid-latitudes of the northern hemisphere; and 14C depletion due to gas exchange with circumpolar Antarctic upwelling water, influencing mainly mid- and high southern latitudes. -from Authors