An assessment of vital water quality parameters of Teesta River closest to barrage region in Lalmonirhat district of Bangladesh

Abstract

This study was conducted to monitor the key water quality parameters of Teesta river ecosystem closest to Teesta barrage from July 2018 to April 2019 (10 months) situated in the Lalmonirhat district of Bangladesh. Water samples were collected twice in every month from different six sampling sites selected from the upstream and downstream regions of the barrage. Monitored minimum temperature (21.67 ºC) was recorded in the month of January and it was maximum in the month of July (32.03 ºC). Gradual increase of temperature was recorded from March to July (early monsoon) indicated that water temperature was normally uplifted according to the seasonal change. The observed dissolve oxygen level showed relatively in the month of July (6.5 mg/l) and higher in the month of January (8.1 mg/l). Average temperature and dissolved oxygen fluctuations were significantly (p< 0.05) varied among different sampling months. Inverse relationships were observed between water temperatures and dissolve oxygen level. It is important to note that downstream region of barrage had slightly higher DO level than the upstream region that might the impact of barrage water flow. The recorded pH revealed that slightly alkaline pH level found in all the year round (7.1 to 7.7). Besides, both nitrate-nitrogen and phosphate-phosphorous levels were observed little higher in the late monsoon. The findings of this study suggested that better ecosystem health (temperature, pH and abundance of plankton) was observed in early monsoon season.