Delayed Nutrient Responses to the Liming of Lake Gårdsjön, Sweden

• Published in: Ambio 1988-01, Vol.17 (1), p.22-27
• Main Author: BROBERG, O
• Format: Article
• Language: English
• Subjects: Aluminum; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Lakes; Lentic systems; Liming; Liming Acid Lakes; Nitrogen; Particulate matter; Phosphorus; Phosphorus acids; Sediments; Watersheds
• ISSN: 0044-7447; 1654-7209

The acidified lakes Gårdsjön and Stora Hästevatten (reference lake) have been monitored since 1980. These lakes are situated in southwestern Sweden, in an area severely affected by acid deposition. In terms of improvements in pH and alkalinity Lake Gårdsjön was successfully limed (in the spring of 1982). The short-term effect was mainly an increase in dissolved organic carbon (DOC) and chlorophyll a concentrations together with a decrease in particulate-nitrogen and carbon concentrations. Further development was characterized by a mineralization of the "acid benthic flora" (algae and sphagnum), which was extensive in Lake Gårdsjön before liming. This mineralization episode led to a further increase in DOC concentrations accompanied by increases in organic nitrogen and particulate phosphorus, nitrogen and carbon. This increase in particulate organic matter was mainly due to a bloom of the phytoplankton Cosmocladium perissum (Roy & Biss.). This algal bloom was followed by a period of low oxygen concentrations in the deeper areas of Lake Gårdsjön, with a subsequent release of sediment phosphorus. This paper focuses on the possible mechanisms underlying the measured concentration changes of phosphorus, nitrogen and organic carbon in relation to the acid reference lake and compares these results to those from other limed lakes. The question of whether or not liming in general can fully restore the chemical bases for primary production (i.e. the availability and amounts of the limiting nutrients phosphorus and nitrogen) is addressed.