Distribution and composition of suspended matter in waters

Abstract

By suspension, we understand particles of different origin suspended in seawater from 1 mm to 0.1–0.01 mm in size. Water samples obtained with sunken pumps and bathometers for 200 liters. The suspensions obtained by the method of semi-automatic membrane ultrafiltration and separation with industrial plate and many chamber separators. In the Indian Ocean 4,000 samples were collected from the surface and vertical sections. This provides quantitative and qualitative data about the contents of the suspended material. The separation method provided samples of suspension weighing several tens and several hundreds of grams. According to collected materials, maps were compiled of the quantitative distribution of the suspension in the surface waters, and also the vertical sections across the southern part of the Indian Ocean, and two meridional sections running across the whole ocean. For the surface waters of the Indian Ocean the 0,5–1 g/m3 of suspension contents is typical, which is less than the corresponding data of the Pacific. Towards the coasts the suspension concentrations grows and reaches maximum values near the ice edge due to the development of the phytoplankton. The most striking changes in the concentration of the suspension along the vertical sections were observed in the 0–200 m layer, below this the waters of the Indian Ocean contain usually from 1 to 2 g/m3 of suspension. Towards the continental slopes, the concentration reaches 2–4 g/m3, and sometimes 10 g/m3. In the shelf regions and on the continental slopes in the waters of the open ocean «tongues» and «clouds» could be found with a larger content of suspension. This originates from the fault of the fine sediment material from the shelf. The value of the mean content of suspension for every station was obtained by the method of mean suspended, which turned out to be equal to 1-1,5 g/m3 for the whole bulk of water. The absolute quantity of suspension under the 1 m 2 of the ocean's surface to the bottom was usually estimated from· 3000 to 6000 g.