Effects of static stability and the C/N ratio on aggregation processes of oceanic particles

Abstract

The cumulative numbers of particles obtained from seven waters in the depth range of 0–100 m in coastal seas and in the North Pacific Ocean followed a hyperbolic distribution with two segments on log-log plots (132 sets of data). An alteration of the segment-slope in the fine size classes (1.59–10.08 µm in the coastal region, 1.59–6.35 µm in the open sea) was assumed to show a loss or a supply of fine particles due to aggregation or disaggregation. We studied relationships between segment slopes, static stabilities of water above the pycnocline which concern the dynamics of particles, and C/N ratios as an indicator of freshness of particles. A negative correlation between the segment-slope of particle size distribution and static stability was obtained, though the slope P of the regression line varied from 0.059 to 0.316. The average C/N ratio in the waters were in the range of 7.5 to 16.3. The slope P negatively correlated to the C/N ratio (r=−0.97). The present results suggested that aggregations of fine-sized particles in the sea are activated in the water with fresh organic matter and with high static stability.