Analyses of the seasonal variations in d15N of settling particles in the western subarctic Pacific using an ecosystem model including nitrogen isotopes

Abstract

Settling particles were collected by time-series sediment trap moored at station KNOT (44N 155E, water depth 770m) from October 25th 1999 to June 20th 2001, and from June 25th 2002 to May 11th 2006. Particulate nitrogen contents and its isotope ratios (d15N) in the collected samples were measured. The results of d15N showed the general variations that are lower during the spring bloom periods and higher during winter periods. In order to analyze quantitatively the factors controlling such variations, we used an ecosystem model including nitrogen isotopes. We will present the analyses obtained with the model.