Study of "tropic status" of a pond through diurnal profiling

The purpose of the study was to ascertain the trophic status of the pond through significant correlation among the physicochemical parameters in a 24 hr period. The work involved a systematic study involving selected physicochemical parameters of two ponds located in Patna, India. It was found out that the content of dissolved oxygen in the Secretariat pond varied with the depth of the pond. Higher value of dissolved oxygen (DO) at surface and at a depth of 0.5 m, in comparison to the bottom, suggests that the diurnal variation of DO is mainly attributed to photosynthetic activities of the phytoplankton. The DO content begins to fall off with the decline of effective sunlight (16:00 hours). Thus, it is evident that the diurnal periodicity of the dissolved oxygen is an indirect reflection of the biochemical pulse of the system. However, at the Adalatgunj pond, clinograde distribution of DO was observed, suggesting water to be eutrophic. The study also revealed the sharp diurnal variations of free CO/sub 2/ at the Adalatgunj pond. The bicarbonate alkalinity was maximum at 12:00 hours suggesting the dominance of HCO/sub 3//sup o/ns by that time. When photosynthetic demand of CO/sub 2/ increases, the required amount is furnished by distribution of bicarbonate ions. As a result, the bicarbonate alkalinity starts decreasing from 12:00 hours-16:00 hours, and starts increasing when the photosynthetic activity ceases (beyond 20:00 hours). Low alkalinity and least variation at Adalatgunj pond is an indicative of eutrophic water. This diurnal study gives information about the trophic status (oligotrophic, eutrophic) of a pond vis-a/spl grave/-vis the various parameters-alkalinity, DO, free CO/sub 2/ etc.