Trace element studies in Laucala Bay, Suva, Fiji

Area of Science:

• Environmental Geochemistry
• Marine Pollution Studies
• Coastal Lagoon Ecosystems

Background:

• Laucala Bay, Fiji, is a coastal lagoon receiving significant freshwater input and adjacent to a densely populated capital city.
• Understanding trace metal sources is crucial for assessing environmental health in coastal ecosystems.
• Anthropogenic activities can introduce pollutants into marine environments, impacting sediment and biota.

Purpose of the Study:

• To investigate the distribution of trace metals (Mn, Zn, Cu, Pb, Cd, Hg) in Laucala Bay surface sediments.
• To assess the relative significance of anthropogenic versus natural sources of trace metals in the bay.
• To correlate trace metal concentrations with sediment characteristics and potential pollution sources.

Main Methods:

• Analysis of surface sediments from 25 sites for particle size, organic carbon, major elements, and trace metals.
• Analysis of suspended sediments and shellfish samples to identify sources and bioaccumulation.
• Geochemical analysis to determine elemental composition and spatial distribution patterns.

Main Results:

• Sediments are predominantly of terrigenous origin, with composition related to bay location.
• Riverine suspended solids represent a significant natural source of trace metals.
• Spatial distribution of trace metals is not fully explained by sediment properties alone, suggesting other influences.

Conclusions:

• Natural sources, particularly riverine input, are major contributors to trace metal loads in Laucala Bay sediments.
• While anthropogenic contributions are suspected, the current degree of trace metal enrichment from these sources is not substantial.
• Further monitoring is recommended to track potential future impacts of human activities on the bay's geochemistry.