The Distribution and Chemical Composition of Organic Particulate Matter in the Sea and Sediments Off the East Coast of South America1

Menzel (1967) showed that concentrations of particulate organic carbon suspended in the sea below about 100 m, adjacent to the continental rise off Peru, ranged between 6 and 15 pg/liter.The mean and range of the values were smaller than those reported by Hobson ( 1967)) Menzel (1964), Menzel and Goering (1966), Parsons and Strickland ( 1962)) Riley, Van Hemert, and Wangersky ( 1965)) and Szekielda ( 1967) from comparable depths in other offshore areas.The purpose of this study was to obtain samples of particulate organic carbon ( POC) off th e east coast of South America ( Fig. 1) to compare with measurements from the Pacific Ocean ( Menzel 1967).The mass and distribution of suspended particulate matter ( PM ) , nitrogen ( PN ) , and phosphorus (PP), and the organic carbon and nitrogen contents of the sediment, were also studied and are compared with relevant data in the literature. METHODS AND MATERIALSSamples were taken with a lo-liter glass and Teflon water bottle at 50-m intervals from 100-200 m; 100-m intervals from 200-1,000 m; from 2,500 m; and from 100-500 m above the sea bottom.The seawater was drained into a glass reservoir using Tygon plastic tubing and immediately filtered in a closed glass system.Samples of 6-7 liters were filtered through metal membrane filters ( Selas Flotronics, 1.2-p-pore diam), and POC and PN were determined using a Perkin-Elmer No. 240 Elemental Analyzer.The filters were combusted before use at 340C in a stream of O2 for 1 hr and contained ca. 10 ,ug of carbon and