Nictemeral variation of some climatic, physical and chemical variables on small lake in Guatapé (Antioquia), Colombia

Abstract

At a tropical lagoon in the municipality of Guatapé (Antioquia), Colombia was studied the nictemeral variation of several climatic, physical, and chemical variables evaluated during two days of separate samplings through six months in two different hydrologic periods in order to verify that the tropic the magnitude of the variability day-night cycle is greater than the temporary. At seasonal level, the pluviosity presented the highest variation (C. V. = 56.9%) followed by the air temperature (C. V. = 19.7%) which is common in the tropical areas. Through the day-night cycle the most of the studied variables presented significant differences except the pH, which maintained a very low variation during the whole time of study (C. V. < 5%) with a slightly acid tendency, which is very common in the natural aquatic systems or without antropic intervention and low productivity. The variation among hours permitted to show significant differentiates for some climatic and limnological variables such as solar radiation, air and water temperatures, wind speed, relative humidity, dissolved oxygen and its saturation percentage, conductivity, alkalinity, and dissolved inorganic carbon associated to the fluctuation of the cycles of light-darkness for all the variables evaluated, except for pH. This lagoon exhibits thermal stratification defined during the period illuminated of the day and a mix or tendency to this during the period nocturnal, proper to the polimixis is predominant in this aquatic system, so the variation of the physical and chemical conditions in the day-night cycle is greater than the seasonal variability (among sampling).