Organic matter runoff from the Don River into the Sea of Azov in the low water period 2007–2020

Based on data from expeditionary studies of the Southern Scientific Center of the Russian Academy of Sciences, using statistical modeling, new quantitative estimates of the runoff of dissolved organic carbon, chlorophyll-a, total suspended solids, particulate organic carbon with the waters of the Don River into the Sea of Azov during the low water period 2007–2020 were obtained. Statistical models were constructed using Weighted Regressions on Time, Discharge, and Season (WRTDS), which provides some of the most accurate quantitative estimates of concentrations and fluxes to date. Seasonal and interannual features of the relevant substances’ concentrations in the river are considered, and their relationship with water discharges is shown. A comparison was made of the runoff of organic matter and suspended solids of the Don in the modern low water period and other periods of the 20th century.