Particulate organic carbon and particulate humic material in the Arabian Sea

Abstract

Variations in particulate organic carbon (POC) and particulate humic material (PHM) were studied in winter (February-March 1995) and intermonsoon (April-May 1994) seasons in the Arabian Sea. Higher levels of POC were found in the north than in the southeastern side of the Arabian Sea close to the coast caused by higher biological production as a consequence of winter overturning. The PHM showed significant aggregation between 100 and 200 m during winter and was negligibly low towards north and relatively more towards south indicating accumulation of humic material. In contrast, PHM occurred in north than in south in intermonsoon. The north south trends cloud be seen in POC and PHM along 64 degrees E in the Arabian Sea. The POC levels were lower in the Central Arabian Sea in winter, than in intermonsoon, its concentration increasing slightly towards north in accordance with the microzooplankton and bacterial production. The abundance of PHM seems to be related to the intensity of biological activity, the nature of organic material and the spatial and temporal variations in biochemical conditions.