Aligarh one of the famous places of Utter Pradesh (U.P) India is richly well-off with wetlands. They support an extensive and regular fishery of various kinds. The carbon dioxide system contributes the fitness of the wetlands, as it serves to buffer the environment against rapid changes in pH and also regulates biological processes in aquatic communities. Free CO₂ was never found to be present in these wetlands of Aligarh region of northern India. Its absence in all the samples may be attributed to increased pH values. It may be also due to its complete utilization during photosynthesis by green aquatic organisms. Alkalinity, which is important for aquatic life, was found to be contributed mainly by Calcium and Magnesium cations forming carbonates, bicarbonates, hydroxide ions. Carbonates were recorded in all the samples collected from these wetlands, whereas bicarbonates were found to be absent in some samples collected from MP wetland where they are represented by hydroxide ions.