Dissolved, particulate and sedimentary humic acids in the mangroves and estuarine ecosystem of Goa, west coast of India

Abstract

Highest concentration of humic acids in all the three forms (dissolved, particulate and sedimentary) was found in the monsoon (June-Sept.) when the salinity was minimum while the lowest concentration was observed in the premonsoon (Feb-May) when the salinity was maximum. Sedimentary humic acids (SHA) level was relatively higher than the dissolved (DHA) and the particulate (PHA) humic acids except in the monsoon when the proportion of PHA exceeded than of SHA. The percentage of organic matter associated with humic acids in the sediments was maximum in the monsoon and minimum in the premonsoon season which may be attributed to the decomposition of the litter from the mangrove swamps as well as to the fresh water inflow from the upstream region. A positive correlation (r = .736) is observed between organic carbon and humic acids in this mangrove ecosystem. Among the three stations, the one with a very thick population of mangroves was found to be the most productive with respect to humic acids.