Despite various measures taken over the years to reduce water pollution, rivers around Dhaka city remain heavily contaminated, according to a recent study. The report, titled The Surface and Groundwater Quality Report 2022, highlights that industrial waste, municipal sewage, and medical waste continue to pollute the rivers surrounding major cities and urban growth centers.
Rivers around greater Dhaka were highly polluted, particularly during the first five months of 2022, according to a report by the Department of Environment (DoE). The DoE tested water samples from 103 points across 26 rivers for this report. In 2021, the study included 29 rivers, though the DoE did not specify how many of them were polluted. Typically, the DoE provides water test results for specific rivers, allowing comparisons with standard parameters, explained Syeda Masuma Khanam, one of the study's editors.
The latest report from the DoE includes water sampling from the Buriganga, Shitalakhya, Turag, Balu, Dhaleshwari, Brahmaputra, Kaliganga, Jamuna, Meghna, Padma, Korotoa, Teesta, Karnaphuli, Halda, Moyuri, Bhairab, Gorai, Rupsa, Pashur, Khakshiali, Ganges, Kirtankhola, Tatulia, Sugandha, Surma, and Kushiara rivers.
The monitoring process included field measurements and the collection of water samples for laboratory analysis, assessing a total of 12 parameters: pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), total dissolved solids (TDS), electrical conductivity (EC), chloride, turbidity, total alkalinity, and salinity.
The water quality of rivers around Dhaka was more degraded during the dry season compared to the wet season.
Water quality improved significantly during the wet season, highlighting a clear link between increased river flow and better water conditions. In April 2022, the dissolved oxygen (DO) level in the Buriganga River dropped to 0.1 mg/L at the Bosila point but rose to 6.26 mg/L during the monsoon in July near the Bangladesh-China Friendship Bridge. By comparison, in 2019, DO levels ranged from 0.2 mg/L to 5.00 mg/L.
DO levels below 5.0 mg/L place aquatic life under stress, with lower concentrations causing even greater harm. Oxygen levels falling below 1-2 mg/L for several hours can lead to significant fish kills. Similar test results were found in other rivers around Dhaka and its suburban areas, such as the Turag, Balu, Shitalakhya, and Dhaleshwari. In addition to these central rivers, rivers in Chattogram and Khulna, including the Karnaphuli and Moyuri, were also found to be severely polluted according to the report's parameters.
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