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Does ionic strength affect the configuration of aquatic humic substances, as indicated by gel filtration?
Author(s) -
HAAN H.,
JONES R. I.,
SALONEN K.
Publication year - 1987
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1987.tb01066.x
Subject(s) - ionic strength , size exclusion chromatography , chemistry , sephadex , dissolved organic carbon , fractionation , environmental chemistry , filtration (mathematics) , chromatography , elution , humus , ionic bonding , humic acid , soil water , aqueous solution , ion , ecology , organic chemistry , biology , fertilizer , statistics , mathematics , enzyme
SUMMARY. 1. The effect of ionic strength on the configuration of aquatic humic substances was studied by gel filtration and dialysis of water from small. Finnish forest lakes of varying colour. 2. Sephadex gel filtration of water from the most humic lake gave similar elution profiles of UV absorbance and dissolved organic carbon (DOC). Gel filtration of unconcentrated samples from all three lakes under natural conditions of ionic strength (I = 1.7 × 10 −4 ) and pH (5.5–6.0) gave similar fractionation of humic substances, despite their widely differing colour (30–350 mg Pt l −1 ) and DOC (5–25mg C l −1 ). 3. Increasing the ionic strength by two orders of magnitude caused considerable retardation on the Sephadex columns of the humic substances, suggesting a decrease in their molecular size and/or shape. 4. Dialysis experiments strongly indicated that ionic strength‐induced changes in the configuration of the aquatic humic substances are indeed real. Hence it is probable that the elution behaviour of aquatic humic substances on Sephadex gels has previously been wrongly attributed to ionic strength‐dependent interactions between the gel and the humic substances.