Organic carbon fluxes to the ocean from high-standing islands

Abstract

The transfer of terrestrially derived (yet poorly quantified) organic carbon to the oceans is an important yet unagreed upon proportion of the world's carbon budget. The few data that exist suggest that high-standing oceanic islands in the southwest Pacific may make important contributions to the overall terrestrial flux of particulate organic carbon (POC) to the oceans. We have determined the POC flux from several streams in New Zealand. With those data and previous measurements from Taiwan and Papua New Guinea, we estimate the POC flux from high-standing islands in the southwest Pacific to be 48 × 1012 g C yr−1, a value slightly lower than previous estimates. These islands, which make up only ∼3% of Earth's landmass, contribute 17%– 35% of the estimated POC entering the world's oceans annually and thus may be important sources of terrestrial carbon to the ocean. Anthropogenic activities, especially deforestation and forest harvesting, have probably exacerbated the natural flux. Few to no data exist for many of these islands and thus a more detailed assessment awaits further measurements.