Seasonal Variation of Temperature, pH, and Dissolved Oxygen Concentration in Lake Rosu, Romania

Lake Rosu (Red Lake) in the Hasmas (Curmaturii) Mountains was created by the natural barrage of the Bicaz River, a tributary of the Bistrita River, in 1837. Measurements in 2009 were performed, using the Hach Lange multi-parameter meter, to determine physical and chemical parameters of water. Basic parameters for the analysis of the ecological conditions were assessed: temperature, dissolved oxygen and pH. Surface water temperature was 2-3 degrees C lower in summer and higher in winter (except during the period of ice cover) compared with spring and autumn data. At depths <7m, the temperature showed constant values of 4-6 degrees C with nearly the same values in autumn and spring. pH values lied between 7 and 8 at the surface as well as in depth. During the summer, pH values decreased from 8 to 7 in the depth. In spring and autumn, the pH values remained constant and identical. The value of dissolved oxygen was good throughout the year. The surface reached values of 10mgO(2)/L annually at depths >7-8m with a limit of 0mgO(2)/L. Lake Rosu becomes a mountain aquatorium which attracts many tourists. However, its degree of pollution is extremely low.