Water Chemistry of the Middle Amur River

This chapter examines water chemistry in terms of iron, organic matter, and nutrients in river, drainage, and groundwater from the middle reaches of the Amur River, to ascertain the watershed environment of the Amur River Basin during 2005–2007. Nitrate-N concentration was 0.46 ± 0.38 mg/L for river water and 1.9 ± 5.0 mg/L for groundwater, corresponding respectively to 87 ± 11 % and 39 ± 42 % of total inorganic nitrogen. Dissolved iron concentrations were 0.10–1.08 mg/L for river water and 0.39 ± 0.26 mg/L on average. A positive correlation was found between dissolved organic carbon (DOC) and dissolved iron concentrations in river water. However, the groundwater had average iron concentrations of 4.9 ± 3.1 mg/L and 4.3 ± 9.9 mg/L of DOC concentration, and there was no correlation between DOC and dissolved iron concentrations. The results indicate that wetland and forest areas are important in the export of dissolved iron and organic matter in the middle reaches of the Amur River. In the groundwater system, sources of dissolved iron and organic matter are independent for each underground environment, because of differences in geologic media, groundwater flow, and redox conditions.