Atmospheric Input of Phosphorus to Remote Tropical Islands

Abstract

Atmospheric particulate phosphorus has been measured in the tradewinds of the Hawaiian and Samoan islands. The concentration of phosphorus range from 300 to 800 pg m-3 and averages about 500 pg m-3. Reactive phosphorus comprises 20-35 percent of the total phosphorus, persulfate persulfate releasable phosphorus 20-35 percent, and acid-soluble phosphorus 40-60 percent. The reactive phosphorus appears to be of crustal origin, while the acid-soluble fraction is of marine origin. The origin of the persulfate releasable phosphorus is not readily apparent. The acid-soluble fraction may be either organic or inorganic in nature. The persulfate releasable fraction appears to be comprised of organic material. The net phosphorus input to the vegetation on the windward sides of these islands is estimated to be 0.025-0.030 kg ha-1 yr- 1 . The value amounts to percent of the phosphorus deposition measured at an island site. It appears that bulk precipitation samples are easily contaminated in regions of intense biological activity.