Ecological and public health risk assessment of potentially toxic elements in the surface sediments of the Pasur river estuary, Bangladesh.

Potentially toxic elements (PTEs) in the surface sediments of the Pasur river estuary was investigated to assess its distribution, potential sources, and current dangers to ecological and public health. The Pasur River is a tidal, meandering, perennial river in south-western Bangladesh with a considerable number of fisheries and industrial activities. Sediment samples were collected from seven sampling points from January to December 2022 to assess the contamination level of six potentially toxic elements (Pb, Cr, Cd, As, Cu and Zn). Flame Atomic Absorption Spectrophotometer was utilized to detect the concentration of PTEs by following some sequential analytical procedure. Concentration of PTEs followed the reducing trend of Zn > Cr > Pb > As > Cu > Cd with the mean value of 61.04 > 49.15 > 26.58 > 10.28 > 6.28 > 1.59 mg/kg, respectively. The principle component and cluster analyses justified the anthropogenic source of the studied PTEs. The mean values of contamination factor (CF), geo-accumulation index (Igeo) and enrichment factor (EFc) showed that Pb and Cd were highly responsible for sediment (uncontaminated to moderate) contamination. Pollution load index (PLI) indicated higher pollution of sediments near the port areas. Potential ecological risk index (PERI) indicated low to moderate risks due to the contaminated sediment. However, the contamination of sediment was not associated with the non-carcinogenic (HQderm and HI < 1) and carcinogenic (CRderm < 10-6) risks due to the dermal contact. Although the risks were within the tolerable limit, regular monitoring is suggested to reduce the risk of PTEs contamination.

Freshwater pearl culture in Bangladesh: Current status and prospects.

Freshwater pearl farming is an emerging sector of aquaculture in Bangladesh which plays a growing role at major jewelry markets. With some improved techniques, high quality image or designer pearls are now produced from freshwater mussels Lamellidens marginalis. Yet it is difficult to reach in conclusion as the quantities produced, culture techniques used, and the upgrading of the existing culture technique are not well documented. Furthermore, many obstacles such as proper dissemination of culture technologies among the interested peoples, optimization of the culture environment and culture methods, standardization of breeding protocol and so on need to be addressed by the scientific community. This review article reports for the first time about the status of freshwater pearl culture in Bangladesh highlighting the fundamentals of pearl production, culture techniques used in farms, challenges, and prospects for upgradation of current culture principles in Bangladesh.

Seasonal dynamics of phytoplankton community and functional groups in a tropical river.

Functional classification of phytoplankton could be a valuable tool in water quality monitoring in the eutrophic riverine ecosystems. This study is novel from the Bangladeshi perspective. In this study, phytoplankton cell density and diversity were studied with particular reference to the functional groups (FGs) approach during pre-monsoon, monsoon, and post-monsoon at four sampling stations in Karatoya River, Bangladesh. A total of 54 phytoplankton species were recorded under four classes, viz. Chlorophyceae (21 species) Cyanophyceae (16 species), Bacillariophyceae (15 species), and Euglenophyceae (2 species). A significantly higher total cell density of phytoplankton was detected during the pre-monsoon season (24.20 × 103 cells/l), while the lowest in monsoon (9.43 × 103 cells/l). The Shannon-Wiener diversity index varied significantly (F = 16.109, P = 000), with the highest value recorded during the post-monsoon season. Analysis of similarity (ANOSIM) identified significant variations among the three seasons (P < 0.0001, R = 0.9518). The similarity percentage (SIMPER) analysis pinpointed Ulothrix spp. (Melosira granulate and Cymbella spp.) as the most contributory species are causing such a noticeable difference. Fifty-four phytoplankton species recorded during the study period were classified into 20 functional groups, whereas D/J/M/MP/X1 was considered the most abundant FG in the Karatoya River. FGs of the Karatoya River were influenced mainly by the nutrients (PO4-P and NO3-N) enrichments. As a novel investigation on FGs of phytoplankton in Bangladesh, this study recommends additional surveys in other rivers and floodplains to improve our understanding of phytoplankton diversity and functional groups.