Aggregation of aquatic humic substances

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doi: 10.1016/0009-2541(84)90148-7
Authors:Tipping, E.; Ohnstad, M.
Author Affiliations:Primary:
Freshwater Biol. Assoc., Ambleside, United Kingdom
Volume Title:Chemical Geology
Source:Chemical Geology, 44(4), p.349-357. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0009-2541
Publication Date:1984
Note:In English. 18 refs.; illus. incl. 2 tables
Summary:Humic substances (HS) were isolated from the Penwhirn reservoir (PR) of Galloway, Scotland, and from surface water samples of Esthwaite Water (EW) in Cumbria, England. Their removal from solution by centrifugation was studied as a function of pH, humic concentration and molecular weight, and CaCl2 concentration. Large amounts (= or <50%) of PR HS could be removed but only small amounts (<3%) of EW HS. At pH >5, removal of PR HS by Ca2+ can be explained satisfactorily in terms of decrease in HS induced by complexation with the cation, but removal induced by protonation of the PR HS is unusual in that it decreases with increasing humic concentration. The results suggest that PR HS comprise a range of molecules differing in solubility, with the high-molecular-weight (40 000) components being the least soluble. The EW HS consist of molecules of average molecular weight 5000 and resemble similarly sized PR HS in that they remain unaggregated in solution even when highly complexed with Ca2+. [P.Br.]
Subjects:Alkaline earth metals; Calcium; Complexing; Geochemistry; Humates; Humic acids; Humic substances; Hydrochemistry; Hydrology; Metals; Organic acids; Organic compounds; PH; Solubility; Surface water; Surveys; Cumbria England; England; Europe; Galloway Scotland; Great Britain; Scotland; United Kingdom; Western Europe; Calcium ion; Esthwaite Water; Organic materials; Penwhirn Reservoir
Coordinates:N540000 N553000 W0021500 W0051500
Abstract Numbers:85M/0647
Record ID:1985006238
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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