THE SEASONAL AND VERTICAL DISTRIBUTION OF SUSPENDED PARTICULATE MATTER IN AN AREA OF THE NORTHEAST PACIFIC OCEAN1

Concentrations of the particulate matter, particulate organic carbon, and particulate carbohydrate were determined in an area of the northeast Pacific Ocean, at depths between the surface and 4,000 m, on six occasions in two years. Below 250 m, concentra­ tions of particulate matter ranged from 30 to 1,000 mg/mV particulate organic carbon from 8 to 110 mg/m3, and particulate carbohydrate from undetectable to 30 mg/m3. There was more particulate matter in winter than in spring and summer. This temporal variation appeared to be related to variations in advection. The particles making up about 90% of the mass of the particulate matter with diameters greater than about 2 fi ranged between 8and 44-/* diameter. Sinking rates were calculated (0.1 to 10 m/day) and were slow compared with horizontal speeds. Thus, the influence of phytoplankton production in the area of the concentration of particles below 250 m in that area was of minor importance. Below 250 m, the ratios of the variables and particle size showed no consistent changes with depth, suggesting that the particles were not rapidly oxidized while suspended in the water column.