Seasonal variations of chemical properties of water of the Kaptai lake, Rangamati, Bangladesh

Abstract

The chemical properties are the most important factors in the aquatic environment. The present study was carried out to analyze the chemical properties of the water of the Kaptai lake, Rangamati. The investigation was done from December, 2007 to November, 2008, during four seasons in two sites and three sub-sites. The main aim of the present research was to analyze the water quality of the Kaptai lake. Chemical properties of the water of this lake were determined by different standard methods. The chemical properties of water varied in different sites and seasons. The value of pH and dissolved oxygen (DO) was higher in undisturbed (UD) area than in less disturbed (LD) and disturbed (D) area (UD>LD>D). The nitrate (NO₃) value was higher in disturbed area than undisturbed and less disturbed area (D>UD>LD). The phosphate (PO₄) value was higher in less disturbed area than disturbed and undisturbed area (LD>D>UD). The electrical conductivity (EC), biological oxygen demand (BOD) chemical oxygen demand (COD) were higher in disturbed area than less disturbed and undisturbed area (D>LD>UD). The potassium (K) value was LD>UD>D. The pH value was higher in winter (W) than in late monsoon (LM), early monsoon (EM) and monsoon (M) (W>LM>EM>M). The NO₃ ^-1 value was EM>M>LM>W>EM. The PO₄ ^-2 value was LM>M>W>EM. The EC value was W>LM>M>EM. The biological oxygen demand (BOD) value was EM> W>LM>M. The DO value was higher in monsoon than late monsoon, early monsoon, and winter (M>LM>EM>W). The COD was EM>M>W>LM. The K value was EM>W>M>LM. The highest value of pH, K, NO₃ and BOD were recorded in the Kaptai hydroelectricity project area (site –A) and the highest value of the DO, EC and COD were recorded in the Longudu area (site-B). This study is the first initiative to assess the detail chemical properties of water of the Kaptai lake.

Jahangirnagar University J. Biol. Sci. 6(2): 11-17, 2017 (December)