RT Journal Article ID 079288dd45460fcf A1 Linnik, P.N. A1 Ivanechko , Ya. S. A1 Linnik, R. P. A1 Zhezherya, V. A. T1 Humus Substances of Surface Waters and the Peculiarities of Their Distribution among Various Fractions JF Hydrobiological Journal JO HYD YR 2013 FD 2013-10-02 VO 49 IS 5 SP 90 OP 111 K1 humus substances K1 humic acids K1 fulvic acids K1 rivers, reservoirs K1 lakes K1 molecular-mass distribution K1 average molecular mass AB Results of the study of humus substances in water bodies of various types, including rivers, lakes, and reservoirs, are given in the paper. It has been shown that their maximum concentrations are registered in the rivers of the Pripyat River basin. In the studied water bodies, a relative contribution of humus acids to the total content of dissolved organic matter (% Corg) on the average accounts for 56.0−82.4%. The fraction of fulvic acids (81−95%) prevails in the composition of humus substances. Data on the molecular-mass distribution and relationship between the fractions of humus substances differing in their molecular mass depending on the method of their detection are discussed. The values of the average-number and average-mass molecular mass of humus substances, including the fractions of humic and fulvic acids, have been calculated. It has been shown that their average-mass molecular mass accounts for 2.3−12.2, 6.9−12.2, and 1.8−9.0 kDa. PB Begell House LK https://www.dl.begellhouse.com/journals/38cb2223012b73f2,0b3f864a50437d45,079288dd45460fcf.html