Relationship Between Chlorophyll-A, Ph, and Dissolved Oxygen in a Tropical Urban Lake Waters: A Case Study From AIr Hitam Lake, Samarinda City, Indonesia

The relation between chlorophyll-a concentration, pH, and dissolved oxygen in a tropical urban lake is important but relatively unknown. Globally, due to population growth and urban area expansion, it is predicted that the number of constructed urban lakes will also increase. The main objectives of this paper were to observe the general patterns and connections between these parameters in the Air Hitam Lake in Samarinda City, East Kalimantan, Indonesia. The variation of chlorophyll-a, pH, and DO were obtained at five different stations. Eight weekly measurements were conducted between mid-October and mid-December 2022 (n = 40). The linear model relationship between pH and chlorophyll-a in our study resulted in a significant positive correlation (R2 = 0.16; p-value = 0.01). A significant correlation between DO and chlorophyll-a was also identified, with an R2 = 0.10 and a p-value = 0.042. Lastly, a significant positive correlation was also identified between pH and DO (R2 = 0.48; p-value = 6.02E-07). Algal photosynthesis is a key factor responsible for the changes in both pH levels and the presence of dissolved oxygen. In Air Hitam Lake, the substantial amount of algae, as indicated by the concentration of chlorophyll-a, significantly influences the pH of the water and the fluctuations in dissolved oxygen.