SEDIMENT GRANULOMETRY AND ORGANIC MATTER CONTENT IN THE INTERTIDAL ZONE OF THE SUNGAI BRUNEI ESTUARINE SYSTEM, NORTHWEST COAST OF BORNEO
M. Belal HOSSAIN1*, David J. MARSHALL1 & Senapathi VENKATRAMANAN2
1Biological Sciences, Faculty of Science, Universiti Brunei Darussalam, Jalan Tunkgku Link, Gadong- BE1410, Brunei Darussalam. Email: mbhnstu@gmail.com
2Institute of Environmental Geosciences, Department of Earth and Environmental Sciences, Pukyong National University, 599-1, Daeyeon-dong Nam, Busan - 608737, Korea
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Abstract
Most of the estuarine and ocean bottoms are covered with sediments making this the largest habitat on our planet. Grain size data of the estuarine sediments are of great importance in differentiating various depositional microenvironments and also useful for assessing the textural characteristics of the habitat in benthic ecological studies. Here we use grain size analysis of the intertidal surface sediments along the Brunei estuary (Borneo, South East Asia) and the result reveals the dominance of sand fractions, and the percentage of dominance follows the order of sand > clay > silt. The sand size fraction was higher at seaward stations, which were poor in organic matter (<4 %), in contrast to the low-energy landward stations, which comprised a higher proportion of fine-grained (clay and silt) sediments and were rich in organic matter (> 5%). This pattern suggests that the intertidal sediments of the estuary derive from a mixed origin, including continental/marine and terrestrial sources, which vary in degree along the estuarine gradient in relation to hydrodynamic wave/current energy (generally low to high in a seaward direction along the estuary). There was strong negative correlation between the sand fraction and the other sediment variables (silt, clay and organic matter), whereas a positive correlation was observed between organic matter and silt/clay. Univariate (ANOVA) and multivariate (PCA) techniques clearly showed significant spatial differences in the sediment variables among the stations investigated, confirming differential energy conditions at different locations. Cluster analysis and PCA helped to discriminate the station groups along the estuary according to their sediment textural properties. This study also revealed that sediment grain size is a key factor influencing the organic matter accumulation in surface sediments. The organic matter observed in different stations is quite in agreement with the widely accepted view of other researchers from the tropical region that fine grained sediments generally have higher amounts of organic matter than the coarse grained one. The high organic matter at landward stations was found to reflect natural (mangroves) and anthropogenic (pollution) organic input.
Keywords:
- grain
- size
- sand
- silt
- clay
- organic
- matter
- Brunei
- estuary
- Borneo
How to cite
M. Belal HOSSAIN, David J. MARSHALL & Senapathi VENKATRAMANAN (2014). SEDIMENT GRANULOMETRY AND ORGANIC MATTER CONTENT IN THE INTERTIDAL ZONE OF THE SUNGAI BRUNEI ESTUARINE SYSTEM, NORTHWEST COAST OF BORNEO