Bindler, R. Dept. of Ecology and Earth Science, Umeå University, richard.bindler@mhs.umu.se
Renberg, I. Dept. of Ecology and Earth Science, Umeå University, ingemar.renberg@mhs.umu.se
Högberg, P. Dept. of Forest Ecology, Swedish University of Agricultural Sciences,

 
RECORDS OF 13C, 15N, AND 34S IN SEDIMENTS OF AN ACIDIFIED LAKE IN SOUTHERN SWEDEN: THE IMPORTANCE OF LONG-TERM MECHANISMS FOR THE EVOLUTION OF LAKE pH
 
Paleolimnological investigations have disclosed an alkalization phase in acid-sensitive southern Swedish lakes, which was attributed to regional land-use changes from long-term human impact. However, analyses of 13C, 15N, and 34S in a sediment core from Härsvatten, an acidified lake, demonstrate a need to re-examine long-term mechanisms affecting lake pH. Changes in 13C and 15N, which have a temporal relationship with changes in diatom-inferred pH, suggest that the alkalization phase had two separate periods: the first period was synchronous with changes in the pollen assemblage resulting from regional land-use changes; the second period occurred after a return to a pre-disturbance pollen assemblage, but along with increasing atmospheric Pb pollution. In Sweden the cumulative deposition of pollutant Pb in the 2000 years prior to industrialization equaled that of the industrial period. Similar to Pb, the cumulative deposition of pollutant S prior to industrialization must have been substantial, but in the acidification debate the role of pre-industrial S pollution has been overlooked. Analysis of 34S in Härsvatten sediments suggest a pre-industrial change in ecosystem S cycling dynamics, which possibly predisposed the lake to the severity of modern acidification (pH 4.5). Lake acidification studies must consider the importance of long-term processes.
 
Day: Wednesday, Feb. 3
Time: 12:00 - 12:15pm
Location: Eldorado Hotel
 
Code: SS32WE1200E