Acid-base characteristics of organic carbon in the HUMEX Lake Skjervatjern

Journal Article · Wed Jan 01 04:00:00 EST 1992 · Environment International; (United States)

DOI:https://doi.org/10.1016/0160-4120(92)90029-4· OSTI ID:6827869

Kortelainen, P; David, M B; Roila, T; Maekinen, I ^[1]

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1. National Board of Waters and the Environment, Helsinki (Finland)

The Humic Lake Acidification Experiment (HUMEX) was launched in 1988 to study the role of humic substances in the acidification of surface waters and the impacts of acidic deposition on the chemical and biological properties of humic substances. This subproject was designed to determine the contribution of organic acids to the acidity of Lake Skjervatjern (the HUMEX Lake) and the impacts of the acidification on the characteristics of organic carbon. In order to get an empirical measure for organic acidity, dissolved organic carbon (DOC) was fractionated, isolated, and base-titrated from each half of Lake Skjervatjern. Hydrophobic acids were the dominant organic carbon fraction; the total organic acid content was generally greater than 80% of the DOC. The reliability of the fractionation procedure was tested with synthetic acids and the Nordic Fulvic acid. The DOC fractions did not show high variation over the 1.5-y acidification period. Hydrophilic acids had consistently greater exchange acidities compared to hydrophobic acids, averaging 12.9 [mu]eq/mg DOC vs. 10.9 [mu]eq/mg DOC, respectively. The dissociation of organic acids during acid-base titrations clearly increased with increasing pH. The high organic anion contribution to the ion balances indicates that humic matter is an important acidity source in Lake Skjervatjern. There are slight signs that the contribution of organic acids to overall lake acidity has decreased since acidification was initiated. 22 refs., 5 figs., 1 tab.

• OSTI ID: 6827869
• Journal Information: Environment International; (United States), Journal Name: Environment International; (United States) Vol. 18:6; ISSN ENVIDV; ISSN 0160-4120
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540320* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
ACID RAIN
ACIDIFICATION
ATMOSPHERIC PRECIPITATIONS
CHEMICAL ANALYSIS
CHEMICAL PROPERTIES
CHEMISTRY
DATA
ENVIRONMENTAL EFFECTS
EXPERIMENTAL DATA
FULVIC ACIDS
HUMIC ACIDS
INFORMATION
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
RAIN
SURFACE WATERS
WATER CHEMISTRY