Spatial Distribution of Physicochemical Parameters for Quality of Coastal Seawater at Saint Martin's Island, Bangladesh

Author: Imtiaz Ahmed Sakib, Ferdousi Begum, Farhana Akter, Md. Arman Hossain, Md. Abu Bin Hasan Susan
DOI: doi.org/10.70279/bmj-v8-i1-1034
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Bangladesh, a nation situated on the Bay of Bengal's northern shore, is endowed with an abundance of natural resources. Saint Martin's Island is only coral-bearing island in Bangladesh Although marine biodiversity of this island is extremely rich due to its ideal habitat, but for natural disasters, many forms of pollution, and other man made activities, the marine ecosystem is always under threat. As a result, it is crucial to understand the current physicochemical status of the seas surrounding the island. In this study, Inverse Distance Weighted (IDW) Interpolation Method was applied to calculate the value of physicochemical parameters at un sampled locations within the scope of the point observations during dry seasons. Coastal seawater samples were collected from nine sampling stations and further analyzed to monitor the spatial distribution of seawater quality through the measurement of physicochemical parameters: pH, temperature, salinity, electrical conductivity (EC), total dissolved solids (TDS), density, dissolved oxygen (DO), viscosity, turbidity and refractive index using different methods. Correlation analysis of the spatial distribution of different parameters showed strong correlations between the parameters. The spatial distribution of concentration nutrients such as nitrate (NO₃₋) and phosphate (PO₄³⁻) were also observed to be critical indicators of seawater quality throughout the surrounding of the island. From the analysis of interpolated distribution of various seawater quality parameters along with concentration of nutrients, it was found that the seawater quality parameters during the sampling season were within the standard limit of characteristics of the seawater. In other words, it was further revealed that TDS, density, viscosity, refractive index, salinity, EC and DO significantly higher than that of permissible limit of drinking water recommended by World Health Organization (WHO) but well in standard in case of permissible limit of seawater. Thus, seawater quality parameters in the coastal area varied on spatial scales and these results may serve as baseline information for coastal management, specifically for the Saint Martin's Island.