earticle

영어

It shows that the longitudinal water quality changes observed along the Tuul River that can be demonstrated by the changes of the concentration of mineralization and ammonium nitrogen. The main pollution source is effluent discharge from the Central Waste Water Treatment Plant (CWWTP) of Ulaanbaatar that can be shown by monthly comparative investigations in the Tuul River in the upstream of Ulaanbaatar (Terelj) and waste water from CWWTP discharges to the Tuul River (Songino) and diurnal study in the discharge from the CWWTP. At Sta MO8, the ammonium nitrogen concentration was highest in April (after snow melting) and lowest in July between 2005 and 2008, which might be related to dilution due to rain events in July. At Sta. M05, the ammonium nitrogen concentration was low throughout the period of investigation. Despite this seasonal variability, the concentrations of ammonium nitrogen and conductivity at Sta. M08 were generally much higher than those at Sta. M05. Moreover there was a very large change in water quality during a day. Ammonium concentration was very high and variable, being correlated with conductivity. There was very little dissolved oxygen at night. This is because of the microbial consumption of oxygen. High ammonium concentration and low dissolved oxygen is very bad (toxic) for fish. Therefore, it seems that Ulaanbaatar is a significant source of pollutants regardless of season in the Tuul River.