Subsurface Dynamics of Physicochemical Parameters in the Pasur River Estuary, Bangladesh: A Baseline Assessment

The investigation aimed to record the vertical distribution of some key physicochemical parameters in the Pasur River estuary across five sampling stations using a CTD. Each sampling zone demonstrated varying depth according to the local bathymetric feature. Data were collected at one-meter intervals, ranging from 6 to 22 vertical layers, according to the stations. Pressure exhibited a consistent linear increase with depth, as expected in aquatic environments. Temperature profiles showed overall stability around 29°C, with minor variations at greater depths in some stations. Turbidity generally demonstrated an increasing trend with depth, though sporadic deviations were observed. Conductivity values remained predominantly stable across depths at all stations (nearly 1 S/m) with marginal deviations, reflecting a relatively homogeneous ionic composition corresponding to salinity, which ranged from 4.47 to 5.65 PSU. pH levels exhibited marginal but steady increases (within approximately 0.1 units) along the vertical profiles, suggesting a well-buffered system. These baseline findings provide critical insights into the estuarine dynamics of the Pasur River and contribute valuable reference data for future studies on environmental monitoring, biogeochemical cycling, and ecosystem modelling.