Concentration and Behavior of Detrital Mineral Grains Suspended in the Water Column of the Open Sea in the Western Pacific

Abstract

The pattern of distribution of detrital mineral grains in the water column wasinvestigated at three stations in the western Pacific during July through August of 1979.The sedimentation of detrital mineral grains was also studied using piston cores from twosites adjacent to the three stations. The concentration of suspended detrital mineral grainsin the subsurface waters becomes lower with increasing distance from the land, and shows aprominent peak in the intermediate zone of the water column. The sharp increase in waterdensity and viscosity in the pycnocline in the intermediate zone decreases the settling velocityof grains, and may result in the accumulation of falling grains in the intermediate layer.Proportion of detrital mineral grains to organic remains in the sediment was more than twoorders of magnitude larger than in the overlying water column, and reasons for this arebriefly discussed.