Atmospheric intertropical convergence impacts surface ocean carbon and nitrogen biogeochemistry in the western tropical Pacific

Concentrations of inorganic and organic carbon and organic nitrogen, as wel l as other hydrographic and biogeochemical variables, were measured in the oligotrophic waters of the western South Pacific Ocean (5-35 degrees S; 170 degrees W). With those data, we assess the impact of the intertropical con vergences of the western tropical Pacific Ocean on surface ocean biogeochem istry. Low salinity, oligotrophic waters of the western tropical Pacific un derlying regions of high net precipitation are characterized by concentrati ons of organic carbon and nitrogen that are elevated relative to higher sal inity (lower net precipitation) zones. We hypothesize that water column str atification, forced by high net precipitation, favors enhanced rates of N-2 fixation, with resultant elevation of organic carbon and nitrogen concentr ations in the region. An effect of anthropogenic ocean warming and the asso ciated increased hydrologic cycle in the tropical Pacific may be to alter t he biogeochemical cycling of carbon and nitrogen through enhancement of N-2 fixation.