Phosphate, carbonate and organic matter distribution in sediment cores off Bombay-Saurashtra coast, India

Abstract

Phosphate, organic matter and calcium carbonate content in five sediment cores (three from the outer shelf one from the slope and one from the basin) from the Arabian Sea have been determined. The distribution pattern indicates their close genetic relationship. The total phosphorus value is high in the core from the slope, almost uniform in the cores from the outer shelf and a core from the nearby basin, but poor in a core (no. 3) considered to be from a 'closed basin' within the shelf. The total phosphorus is maximum (2140-1120 ~kg/gm or 1.04-0.84% P@d2@@O@d5@@ on a carbonate-free basis) in the upper 7.5 cm of the slope sediment and minimum (105-80 ~kg/gm or 0.025 0.022% P@d2@@O@d5@@) in similar sediment on the shelf. It is also higher in the oolithic fractions of the cores. The organic carbon closely fluctuates with increase and decrease of the phosphate content and ranges from 4.655% with 1.04% P@d2@@O@d5@@ in the top part of the core from the slope and 0.385% with 0.160% P@d2@@O@d5@@ in the bottom part of the core from the shelf. Calcium carbonate percentage is uniform in the sediments from the slope and basin region, but varies considerably in the cores from the shelf