In Bangladesh, a nationwide lockdown was imposed on 26 March 2020, due to the COVID-19 pandemic. Due to restricted emissions, it was hypothesized that the air quality has been improved during lockdown throughout the country. The study is intended to assess the impact of nationwide lockdown measures on air quality in Bangladesh. We analyzed satellite data for four different air pollutants (NO 2 , SO 2 , CO, and O 3) to assess the changes in the atmospheric concentrations of pollutants in major cities as well as across the country. In this study, the concentrations of NO 2 , SO 2 , CO, and O 3 from 1 February to 30 May of the year 2019 and 2020 were analyzed. The average SO 2 and NO 2 concentrations were decreased by 43 and 40%, respectively, while tropospheric O 3 were found to be increased with a maximum of > 7%. Among the major cities, Dhaka, Gazipur, Chattogram, and Narayanganj were found to be more influenced by the restricted emissions. In Dhaka, NO 2 and SO 2 concentrations were decreased approximately by 69 and 67%, respectively. Our analysis reveals that NO 2 concentrations are highly correlated with the regional COVID-19 cases (r = 0.74). The study concludes that the lockdown measures significantly reduced air pollution because of reduced vehicular and industrial emissions in Bangladesh.

Abstract:The study was conducted to observe the status of fisheries resource of Tanguar haor, one of the large wetland in the north eastern part of Bangladesh. For this purpose the whole study was completed in two parts: interviewing with local people and analyzing the water quality. Indiscriminate harvesting of mother fishes, use of agrochemicals, sedimentation on haor basin and habitat destruction were found as major causes of fisheries resources degradation in the study area. Most of the water quality parameters were found good which were within the standard level set by Government of Bangladesh for fisheries. However, EC and TDS were found higher than the recommended level for fish production.

This study deals with the investigation of water quality of the Buriganga river, Dhaka. For this purpose, samples were collected from five locations of the Buriganga river of Bangladesh during wet (monsoon) and dry (winter) season in 2011 to determine the spatial distribution and temporal variation of various water quality parameters. Water samples were collected from three different depths of river. The color was light brown in wet season and slightly black to black color in dry season. The water was found slightly acidic to slightly alkaline (6.6-7.5). Water temperature ranged from 18.2 o C (dry) to 27.04 o C (wet). The river was found to be highly turbid both in dry and wet season. Biochemical Oxygen Demand (BOD), Electric Conductivity (EC) and Total Dissolved Solids (TDS) were found higher in the dry season compared to that of wet season, while Dissolved Oxygen (DO) was found higher in wet season. The mean values of parameters were EC: wet-1685 µs/cm, dry-2250 µs/cm; DO: wet-4.9 mg/L, dry-3.7 mg/L; BOD: wet-26.4 mg/L, dry-33.4 mg/L; TDS: wet-238 mg/L, dry-579 mg/L; transparency: wet-24.6 cm, dry-22.8 cm.

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