Integrated Multivariate and Index-Based Assessment of Seasonal Water Quality and Heavy Metal Risks Surrounding a Coal Power Plant in Coastal Bangladesh

This study evaluates the water quality in areas surrounding a coal power plant in the Southwestern coastal region of Bangladesh, with a focus on potential risks to aquaculture suitability and drinking water security. To improve regional relevance, monsoonal hydrological variability was explicitly considered as a primary driver of water quality in this coastal deltaic environment. Multivariate analyses including the PERMANOVA, PCA and HCA was employed to identify patterns, group similarities and statistically quantify seasonal differences in water quality. Additionally, index-based analyses (CCME WQI, HPI, HEI and CF) were used to simplify the overall water status and pollution intensity for aquaculture and drinking purposes. The multivariate analysis indicated strong seasonal contrast, with the dry season showing high iconic concentrations whereas the wet monsoon was influenced by elevated turbidity, organic loads and metal concentrations. The CCME WQI indicated that the water suitability for aquaculture declined notably during the wet season with 50% of the stations shifting from fair to marginal category mostly due to oxygen depletion and elevated heavy metal contents. Significant heavy metal contamination was found at multiple locations (e.g., S3, S6, and S8), particularly during the monsoon season, rendering them unfit for drinking water use. Furthermore, the spatial distribution patterns revealed high contamination zones near the discharge pathway. These localized effects highlight the sensitivity of coastal-marine transition zones to coal-based industrial operations and underscore the need for continuous monitoring and sustainable management in coastal areas.