Increased colour and organic acid concentrations in Norwegian forest lakes and drinking water: a result of increased precipitation?

Recently there have been major increases in water colour and dissolved organic carbon (DOC) in many forest lakes that serve as drinking water reservoirs in the southern part of Norway. We studied changes in the physical and chemical properties in (I) a selected group of lakes and (II) raw water from...

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Bibliographic Details
Published in:Aquatic sciences 2004-06, Vol.66 (2), p.231-238
Main Authors: HONGVE, Dag, RIISE, Gunnhild, KRISTIANSEN, Jan F
Format: Article
Language:English
Subjects:
Acidity
Carbon
Chemical properties
Dissolved organic carbon
Drinking water
Earth sciences
Earth, ocean, space
Exact sciences and technology
Forest floor
Freshwater
Geochemistry
Hydrology
Hydrology. Hydrogeology
Lakes
Leaching
Mineralogy
Organic acids
Organic matter
Raw water
Silicates
Water geochemistry
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Summary:Recently there have been major increases in water colour and dissolved organic carbon (DOC) in many forest lakes that serve as drinking water reservoirs in the southern part of Norway. We studied changes in the physical and chemical properties in (I) a selected group of lakes and (II) raw water from the municipal waterworks of Oslo since 1983 and 1976, respectively. The largest increase in DOC and water colour occurred between 1997 and 2001. Statistically significant correlations are seen between water colour and accumulated amounts of precipitation, while variation in temperature had no apparent effect. Despite significant reduction in sulphate concentrations in precipitation and lake waters since 1980, the lakes were more acidic in 2000 and 2001 than in previous years. Increases in colour and acidity, together with somewhat minor changes in DOC concentrations, indicate changes in the physical and chemical properties of the natural organic matter (NOM). Alteration in properties of NOM is most probably caused by increased precipitation that has changed the water pathways in the catchments and increased the leaching of organic components from the upper forest floor.
ISSN:1015-1621
1420-9055
DOI:10.1007/s00027-004-0708-7