Abstract
The study of organic matter characterisation in coastal sediment is useful for understanding how dissolved organic matter (DOM) reactivity influences the fate of pollutants in the aquatic environment. However, there is little information available on the structural properties of DOM in coastal sediment. Chemical analysis, UV-Visible (UV-Vis) absorbance, fluorescence, and Fourier-transform infrared (FTIR) spectroscopy were used in this work to characterise and compare the components of water-extractable organic matter (WEOM) fractions from sediment from an estuary, a coastal area, and a port in Peninsular Malaysia, Malaysia. The elemental analysis (H/C and C/N ratios) of the three samples differed, which coincided with the findings of optical indices estimated from UV-Visible and fluorescent spectroscopy analyses. WEOM had an average output of 7.05 to 8.47 mg/L and was very dominating with heavy fraction organic carbon (HFOC). In DOM-KS and DOM-K sediments, the allochthonous component with a high degree of condensation and the aromatic compound was the dominating composition. Meanwhile, the DOM-KT possessed a high autochthonous composition as well as carboxylic and phenolic content. Correlation analysis indicates that the aromaticity index SUVA254 and humification index (HIX) have positive correlations. The combined results of the chemical and spectroscopic analyses indicate that different coastal ecosystems, with the integration of various human and land activities, produce variations in DOM in the coastal area.
Highlights
Coastal areas, which serve as the dynamic interface between land and marine ecosystems, play critical roles in global carbon cycling
Coastal surface sediments serve as a major carbon burial interface, receiving huge amounts of organic carbon generated in upper waters, degrading, and eventually burying it [1]
Our findings have shown that there are variations in the sources of marine sediment dissolved organic matter (DOM) from different backgrounds, depending on land activities, which could be associated with land-derived input and human activity
Summary
Coastal areas, which serve as the dynamic interface between land and marine ecosystems, play critical roles in global carbon cycling. It was estimated that 80% of the total organic carbon preserved in marine sediments is found within the deltaic and shelf regions. Coastal surface sediments serve as a major carbon burial interface, receiving huge amounts of organic carbon generated in upper waters, degrading (mainly by microorganisms), and eventually burying it [1]. On the other hand, collect natural and anthropogenic products from the overlying water, functioning as both a sink and a source of contaminants. Coastal sediments may function as a non-point source of contaminants, especially damaging to species and human health via trophic transfer. Coastal sediment has a lower organic carbon concentration and a greater salt content than soil, making organic matter characterisation more challenging in sediment [2]
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