ABSTRACT

Molecular weights of humic acids separated from two lake and three marine sediments were measured by gel filtration through Sephadexes. The results indicate that mol. wt. of humic acid distributes from less than 700 to over 200, 000. On the basis of mol. wt. the humic acids are divided into three main groups: (1) components with mol. wt. from 100, 000 to over 200, 000 (43-70%), (2) components with mol. wt. from 5, 000 to 10, 000 (8-25%) and (3) components with mol. wt. less than 700 (10-17%). The humic acids gave rise to lower mol. wt. compounds on acid or alkali hydrolysis, but the ratio of the hydrolyzable portion to the total varied from sample to sample. A possible conversion process of sedimentary humic acids is discussed.