Speciation of trace elements in the Lower Baram River sediments

What is it about?

Baram is one of the largest rivers in Malaysian Borneo that drains the extensive tropical forest in Sarawak. The river basin mainly consists of alternating beds of sandstone and shale (technically called turbidites) that are considered to have formed under the sea. These turbidites are under intense weathering due to prevailing climatic conditions. Moreover, the recent degradation of the rain forest has resulted in enhanced erosion and transportation of the sediments to the coastal area. Thus, the study of the river sediments in its lower segment could expose an overall picture of the current state of the environment in the whole river basin. Thus, in this work, we report the concentration of trace elements obtained by bulk digestion and sequential extraction. While bulk digestion dissolves the whole sediment, sequential extraction releases only the trace elements that are easily mobile under the Earth's surface conditions. Using these two sets of results, we have calculated various risk indices (contamination factor, geoaccumulation index, risk assessment code and biological toxicity level) and report the sediment quality. Such information is essential for assessing the trace elements toxicity and bioavailability to aquatic organisms such as fish. Then, using statistical methods, we tried to understand the natural processes and anthropogenic sources responsible for the observed levels of the trace elements in the sediments.

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Why is it important?

This research work presents the levels of trace elements in different carrier phases of the sediments. Moreover, several risk assessment indices were employed to bring out the status of contamination of the sediments. Such information is vital to understand the mobility and biological toxicity of the trace elements. Moreover, from bulk analysis (total digestion), the major geochemical processes that regulate the elemental distribution in the sediments are identified.

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