Modern Analysis of Sediment Contamination in Coastal Wetlands

Coastal wetlands are among the most ecologically significant and threatened ecosystems globally, serving critical functions in biodiversity conservation, nutrient cycling, and water purification. However, the increasing burden of pollution from industrial, urban, and agricultural sources poses significant challenges to their health and sustainability. This study revisits the Mai Po Marshes, a Ramsar-listed wetland in Hong Kong, to analyze sediment contamination and its ecological implications using both historical data and contemporary methodologies. The research evaluates the spatial and vertical variations in sediment contamination by nutrients and heavy metals, identifying hot spots and assessing potential ecological impacts. The study employs modern analytical techniques, including Geographic Information System (GIS)-based mapping for spatial distribution, advanced toxicity bioassays for ecological risk assessment, and multivariate statistical analyses to identify relationships between contaminant sources and ecological effects. Key findings reveal significant contamination in surface sediments, particularly for nutrients like nitrogen and phosphorus, and heavy metals such as copper and zinc, with higher concentrations in industrially and urban-influenced regions. Despite marked contamination, the low water solubility of these pollutants suggests limited bioavailability under current conditions, aligning with the weak toxic responses observed in bacterial toxicity assays. However, the potential for long-term ecological impacts, including bioaccumulation and biomagnification, raises concerns for the wetland’s flora and fauna, particularly migratory bird species that depend on this habitat.