Water Quality Features in Small Rivers of Khabarovsk During Floods. 1. Major Ions and Nutrients

The results of studying water chemistry in small rivers of Khabarovsk City during spring flood in 2018–2022 are presented. The concentrations of major ions and nutrients in river water are shown to vary widely due to the considerable difference between the water chemistry in snowmelt water, groundwater, and wastewater, as well as waters from worn-out systems of water supply and water disposal. In the early period of snow melting, maximal TDS and the concentrations of chloride and sodium ions in the center of the city in excess of the MAC, and chloride-sodium composition due to the application of deicing agents were found in the water of rivers draining regions with intense traffic. The heaviest pollution of river water with ammonium and nitrate nitrogen and phosphates was recorded in the beginning of spring flood because of their export from catchment surface areas. It is shown that, during spring flood, the concentrations of dissolved substances in the water of many rivers, except for those fed by municipal wastewaters, gradually decrease, and water chemistry becomes hydrocarbonate-calcium.