Abstract
The objective of this research is to obtain the knowledge about decomposition of sinking particulate nitrogen in the twilight zone ( depths below the euphotic zone to 1000m) in the western subarctic Pacific and its influence on the nitrogen isotopic ratio. Samples were collected from March 20th, 2005 to September 18th, 2005 at 150m, 540m and 1000m water depth using time series sediment trap system. First, the simple settling model which could reconstruct the fluxes of settling particles at 540m and 1000m using the settling particle fluxes at 150m as initial values, was developed. In this model, following assumptions were made: 1) Total components sink simultaneously as same aggregates. 2) Organic materials, Calcium Carbonate and Opal in main components of sinking particles decompose in settling process. 3) Particle settling rates increase with depth. 4) Ballast minerals (Calcium Carbonate, Opal and Lithogenic materials) have constant organic matters that are protected from remineralization. We will report the results of analyzing the above objective based on this model.
