Assessment of microplastic contamination in shrimps from the Bay of Bengal and associated human health risk.

Microplastics (MPs) were analyzed in seven shrimp species Tiger shrimp (Penaeus monodon), Red tiger shrimp (Caridina cantonensis), Indian shrimp (Penaeus indicus), Red shrimp (Metapenaeus dobsoni), White shrimp (Penaeus merguiensis), Brown shrimp (Metapenaeus monoceros), and Roshna shrimp (Palaemon styliferus) collected from the Bay of Bengal. The abundance and characteristics of MPs were assessed in the gastrointestinal tract (GIT), which certainly translocated to the muscle of shrimp species. The highest MP abundance was found in C. cantonensis with 7.2 items/individual (25.3 items/g in the GIT and 6.3 items/g in muscle). The prominent types of MPs in shrimp samples were fibers (30 %) and fragments (29 %). The ingestion rate of MPs of black and transparent color was comparatively higher, with 64 % of the ingested MPs were < 100 µm. The primary polymer types detected based on Fourier Transform Infrared (FTIR) analysis were Low-Density Polyethylene (LDPE), High-Density Polyethylene (HDPE), Polymethyl Methacrylate (PMMA), Polyvinyl Chloride (PVC), Polypropylene (PP), and Ethylene Vinyl Acetate (EVA). Results from Scanning Electron Microscopy (SEM) showed rough surface textures and adhered particles on the MPs isolated from shrimps. The margin of exposure for females was 71.42, and for males, it was 80.64, indicating that women in Bangladesh are more likely to be exposed to MPs and face a higher risk than men. Sensitivity analysis revealed that MPs particle size was the most sensitive parameter. These findings provide a comprehensive understanding of MP ingestion, human exposure, and contamination in shrimps of Bangladesh, which can help future monitoring efforts.

Abundance and characteristics of microplastics in major urban lakes of Dhaka, Bangladesh.

Microplastics (MPs) are prevalent in nature due to the proliferation of plastic in the environment. However, the presence of microplastics in lakes is largely unknown in comparison to other aquatic bodies. This study was performed to evaluate the abundance and characteristics of MPs in water, sediment, and fish from three major urban lakes in Dhaka, Bangladesh, namely Dhanmondi, Gulshan, and Hatir Jheel lake. The highest concentrations of microplastics in surface water (36 items/L), sediment (67 items/kg), fish (17 items/individual), and the gastrointestinal tract (4.88 items/gm) were observed. Highest abundance of microplastic in an individual fish was observed in Oreochromis mossambicus from Dhanmondi Lake. The samples were visually examined using stereomicroscope and SEM, which revealed that films were the most prevalent kind of microplastics in both the water and the sediment samples, whereas pellets and foams predominated in the fish samples. Visual observation also revealed MPs dominated by <100 µm in size and transparent in color. According to the Fourier Transform Infrared (FTIR) analysis, the dominant polymers in the analyzed samples were high-density polyethylene, low-density polyethylene, ethylene vinyl acetate, polyvinyl chloride, polycarbonate, cellulose acetate, and polypropylene. MPs were relatively higher in the water and sediment samples of Gulshan Lake, and fish samples of Dhanmondi Lake. The results of this study indicate that microplastic contamination has occurred not only in the water and sediment but also in the inhabitant fishes of the lakes. However, it is discovered that the microplastic intake of fish was significantly related to body weight and length. The implication of the finding suggests that the presence of MPs in urban lakes has raised concerns about the potential human health impact.

Streamflow characteristics of Sangu-Matamuhuri watershed in the southeastern part of Bangladesh.

Quantification of streamflow chatacteristics is considered crucial for designing effective management practices in a watershed. Sangu and Matamuhuri are two major rivers of Chittagong Hill Tracts (CHT's) and main sources of upland freshwater inflows to the south-eastern part of Bangladesh. This study was performed to evaluate the streamflow characteristics of Sangu-Matamuhuri watershed based on 25 years historical observed streamflow and rainfall records. Mean daily discharge data recorded by Bangladesh Water Development Board were collected and analyzed for the period of 1995-2019. Stream flow characteristics were determined in terms of different parameters including mean annual runoff discharge, specific water yield, run-off ratio, peak flow, seasonal flow and flow duration. Various statistical measures including mean, standard deviation, co-efficient of variation, lag-1 serial correlation, Mann Kendall test and Sen's slope estimator were applied to justify these parameters. The mean annual runoff discharges of 2167.77 and 1490.61 million cubic meters (mcm) were measured at the gaging stations at Sangu and Matamuhuri watershed, respectively. Matamuhuri basin showed higher value of specific water yield (1.52 mcm/sq. km) compared to the Sangu basin (1.02 mcm/sq. km). The average annual runoff coefficient value of Sangu watershed was found 0.36 while in case of Matamuhuri watershed it was about 0.49. The mean annual peak discharges of 25 years were found 607.63 m3s-1 and 628.42 m3 s-1 at Sangu and Matamuhuri watershed, respectively. Mann-Kendall Test (MK) and Sen's Slope Estimator method were applied for temporal trend analysis. An increasing trend in runoff observed during wet season which may cause flash floods and a decreasing trend observed during dry season that may cause water scarcity in Sangu-Matamuhuri watershed area. Flow duration curves based on 25 years' hydrological data were developed which showed progressive reduction in flows over time in both the watersheds for three periods 1995-2002, 2003-2010 and 2011-2019 with major changes occurred in Matamuhuri watershed during 2011-2020 which might be due to the impact of land use and land cover changes as well as changes in precipitation pattern. Implications of these findings indicate baseline information that can be used to evaluate the impacts of land use changes and climate change, and thereby may facilitate the planning and local management of water resources in the long term.

Prediction of Hazardous Effect of Heavy Metals of Point-Source Wastewater on Fish (Anabas cobojius) and Human Health.

Aquatic ecosystems are exceedingly contrived due to industrial dispenses, as a huge amount of toxicants especially heavy metals are released, causing drastic effects on aquatic lives and the human body. This study was performed to assess the quality of point-source industrial wastewater at varying percentage levels and their subsequent hazardous effect on fish (Anabas cobojius) and human health. The perceived value revealed that water quality parameters declined with the increase of wastewater concentration and trace metal evaluation index (TEI) ascertained a high level of water pollution due to Cr, Mn, Fe, Co, Ni, Cu, Zn, and As content for all percentages of wastewater. Concentration of wastewater and culture treatment duration largely impacted on fish mortality rate, body dis-pigmentation, mucus secretion rate, coagulation of mucus all over the body, and accumulation of heavy metals by fish samples. Metal pollution index (MPI) indicated low contamination of fish by the measured elements. Zn and Hg exceeded the threshold limit of target hazard quotient (THQ > 1) and contributed significantly to non-carcinogenic health implications for both the population group. Maximum hazard index in adults and children was observed to be 10.638 and 16.548 for 100% effluent at 96-h exposure period and the overall HI value manifested a very high to medium significant health effects regardless of age. Carcinogen Pb showed insignificant risk but Cr and Ni showed extremely high to medium-high risk for both the population group, and children were found more vulnerable receptors than adults. However, source of heavy metals in wastewater and fish samples stipulated anthropogenic sources.

Performance evaluation of FAO Penman-Monteith and best alternative models for estimating reference evapotranspiration in Bangladesh.

Proper assessment of reference evapotranspiration (ET 0 ) is necessary for pastoral activity and water management. The Penman-Monteith FAO56 (ET pmf ) method has been recommended as the identical ET 0 estimation model; nonetheless, it belongs to a vast climatic data requirement. There is an urgent need to discover an ideal alternate model for evaluating ET 0 in particular places where all climatic data is insufficient. The performances of 15 empirical models were assessed to get the best alternative model by comparing it with the PMF-56 model. These 15 models were evaluated by employing a daily scatter plot and three well known numerical approaches: relative root-mean-square error, mean absolute error and Nash-Sutcliffe coefficient in this study. Furthermore, a linear regression model was implemented to calibrate and validate the empirical models' performances throughout the 1981-2005 and 2006-2018 time intervals, separately. The outcomes displayed that the ET pmf rose primarily and declined later on a monthly period with the topmost amount in April and the lowermost amount in January. Overall, the Abtew model was the best alternate method showing the highest determination coefficient values more than 0.85 from January to December. In contrast, the Penman, WMO, Trabert, Valiantzas1, Valiantzas2, Valiantzas3 and Jensen-Haise models presented moderate performances with fewer inaccuracies. Afterwards, modification, the version of the above-described models every month has been upgraded deliberately related to actual. The Abtew model had simplicity in the computation process, only used maximum temperature and solar radiation data and linearly well connected to the PMF-56 model.