Ba Lat estuary is the large mouth of the Red river; every year, the Ba Lat estuary receives million cubic meters of water before the water is dissolved in the sea. Therefore, polluted materials in the water from the continent are also transported to the sea through the estuary. However, the volume of the water pouring into the sea varies with the season. In this paper, the water quality at Ba Lat estuary (Red river) was surveyed in July 2017 representing the Southwest wind season (rainy season) and in October 2017 representing the Northeast wind season (dry season). The research results show that the values of chemical parameters of water at Ba Lat estuary changed according to the season: the average temperature of water in the rainy season was higher than in the dry season; average pH in the rainy season ( ± ) was higher than that in the dry season ( ± ). Parameters such as conductivity, salinity, NO3-N, NH3-N, PO4-P, total grease, Fe and Zn in the dry season were – times higher than in the rainy season. Concentration of some nutrition (including NO3-N; NH3-N; PO4-P and SiO3-Si), heavy metals (Fe, Zn), and total grease in the water were high, in which NO3-N ranged from mg/l to mg/l; NH3-N ranged from mg/l to mg/l, to times higher than the standard of Vietnam. PO4-P ranged from mg/l to mg/l, which was 2 to times higher than the standard. SiO3-Si ranged from mg/l to mg/l. Iron concentration in the water was to times higher than the standard and not different between the two seasons. | Water quality of Ba Lat estuary
