The Influence Of Seasonal Variation Towards Nutrient Distribution And Behaviour In Kelantan River Estuary, Malaysia

Abstract

Nutrients input to estuarine has increased significantly globally, due to the rising of human populations and this results in eutrophication. This study was designed to determine the spatial and temporal distributions of nutrients in Kelantan River estuary during different monsoon seasons and to identify the potential sources and sinks of nutrients in the estuary. The general water quality variables such as salinity, temperature, pH, dissolved oxygen (DO) and total suspended solids (TSS) were monitored in situ. Surface and bottom water samples were collected at 16 sampling points using “Van Dorn Sampler” and were analysed colorimetrically. The results indicate there was a signicant effect of monsoon season on the general water quality of the water column. This study also reveals that the concentrations of nitrate and ammonia in surface and bottom water were highest during the monsoon season, with the range of 16.13-20.39 (mean 17.52 ± 1.42) µM and 11.63-22.75 (mean 17.55 ± 2.43) µM for nitrate and 25.57-88.97 (mean 58.43 ± 21.14) µM and 1.30-99.08 (mean 47.25 ± 32.67) µM for ammonia, respectively. For particulate organic nitrogen (PON) and dissolved organic nitrogen (DON), the concentrations were highest during the premonsoon season while the concentrations of nitrite, dissolved inorganic phosphate (DIP), total particulate phosphate (TPP) and dissolved organic phosphate (DOP) were highest during the post monsoon season. Kelantan River estuary also recorded higher nutrient concentrations in the middle part of the estuary and at the upstream areas, which suggest that the anthropogenic inputs and agricultural factors take place in these areas.