Humic Substance and Dissolved Organic Matter Distribution in the Bureya Reservoir Water System, Central Priamurye, Russia

At the initial stage of filling of the Bureya Reservoir, the dissolved organic carbon (DOC) concentration ranged broadly from 6.2 to 11.7 mg C L⁻¹, and the share of humic substances (HS) attained 55.4–80%. of DOC. The maximum values were observed in the near-bottom horizon and were probably related to soil humus. After the reservoir had been completely filled, the concentration of DOC decreased to 6.3–7.4 mg C L⁻¹, and percentage of HS decreased to 47.8–51.4%. of DOC. Humic substances are formed in the reservoir bed predominantly in the intermediate and near-bottom horizons. The Bureya River and its tributary waters contain mainly dissolved organic substances (90%. and more) of humic origin whose quantitative characteristics are higher as compared to those of the reservoir.