Regularities in the Variations of Chemical Runoff Module in Rivers of the Lena Basin in 2010–2019

The space and time variations of the concentrations of the most informative hydrochemical characteristics in the Lena R. basin are analyzed for two periods (2010–2014 and 2015–2019) in accordance with the most stringent standards for water bodies used for fishery. The constructed maps of the normal annual unit-area discharge for these components give a space and time characteristic of water quality and reveal the dynamics of hydrochemical runoff variations in the recent years. The effect of climate on surface-water regime in the Lena basin is also considered. The unit-area discharge for the majority of dissolved substances, primarily, the major ions and nutrients, was found to increase at an increase in the total precipitation and to decrease at an increase in the temperature, in which case the effect of precipitation is higher. The effect of temperature on chemical runoff is more noticeable in rivers with predominantly snow feeding, and the effect of precipitation, in rain-fed rivers.