Change search
ReferencesLink to record
Permanent link

Direct link
Liming placed in a long-term perspective: a paleolimnological study of 12 lakes in the Swedish liming program
Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
2007 (English)In: Journal of Paleolimnology, ISSN 0921-2728, Vol. 37, no 2, 247-258 p.Article in journal (Refereed) Published
Abstract [en]

Since the 1970s liming has been practised on a large scale in Sweden to mitigate acidification and several thousand lakes and streams are limed repeatedly. The Swedish monitoring program ISELAW (Integrated Studies of the Effects of Liming Acidified Waters) studies the long-term effects of liming. This paper summarizes the paleolimnological part of the program. Sediment cores from 12 lakes were analysed to study the development of the lakes from pre-industrial time until the present, and address questions about natural conditions and the effects of early human impact, acidification, and liming. Diatoms were used to reconstruct the pH history and to study shifts in species composition due to acidification and liming. Analyses of lead and spheroidal carbonaceous particles were applied for indirect dating and as indicators of the atmospheric deposition of pollutants associated with acid rain. Pollen analysis was performed in eight of the lakes to study the vegetation and agricultural history. The natural pH (prior to human disturbance) was between 5.3 and 6.5 in the eight lakes where the complete post-glacial sediment sequence was recovered. Pollen from anthropochores and apophytes indicated early agricultural land use in the vicinity of the lakes from 1000 to 2000 years ago, and pH increased with land use in six of these lakes. Five of the lakes have been acidified during recent decades, and in all 12 lakes some effects of liming were recorded in the diatom assemblage. The lakes show different responses to liming, including a return to a pre-acidification diatom composition or a shift to a state previously not recorded in the lake’s histories. This study accentuates the complexity of biological response to acidification and liming, and highlights the importance of historical perspectives to assess the current state of a lake’s ecosystem and to establish adequate restoration goals.

Place, publisher, year, edition, pages
2007. Vol. 37, no 2, 247-258 p.
URN: urn:nbn:se:umu:diva-11880DOI: doi:10.1007/s10933-006-9014-9OAI: diva2:151551
Available from: 2007-03-15 Created: 2007-03-15Bibliographically approved
In thesis
1. A paleolimnological perspective on liming – implications for defining reference conditions in Swedish lakes
Open this publication in new window or tab >>A paleolimnological perspective on liming – implications for defining reference conditions in Swedish lakes
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Using paleolimnological techniques, I have studied surface-water acidification and the effects of liming in Swedish lakes on a decadal to millennial time-scale. The overall objective was to contribute to the discussion on the fulfilment of goals within the Swedish liming program. One of the main goals of this program is to restore lakes to natural or nearly natural conditions, i.e. to a reference condition as termed in the EU Water Framework Directive. In this context, a key issue is to define reference conditions. This is a central theme of my thesis, as lake sediments offer a unique way to study past lake conditions.

Past lake-water acidity of 12 reference lakes in the Swedish liming program (ISELAW) was determined using diatom analysis of sediment cores. Pollen, lead, and flyash from coal/oil combustion were used as indicators of impact from land use and atmospheric pollution. A general trend in these lakes is an initial decline in pH after lake formation due to natural soil processes, which was then followed by rather low pH values (pH 5.3-6.5). In six of the lakes pH increased as a result of expansion of agriculture (burning, forest grazing) 2000 to 1000 years ago. Local mining and long-range airborne pollution have also impacted the lakes since medieval time. These results show that the conditions of the study lakes were not natural prior to industrialization and recent (20th century) acidification.

The ISELAW lakes were selected on the basis of representing typical limed lakes, and they have been limed and monitored since at least the 1980s. A comparison of chemical/biological monitoring data and the paleolimnological data gives somewhat diverging results. Most of the monitoring data suggest that the lakes were subjected to acidification during the 20th century, but the paleolimnological data can only identify clear evidence of acidification in five of the 12 lakes, hence, all lakes were probably not recently acidified. According to conclusions from monitoring the lakes have recovered following liming. The paleolimnological data give a more complex picture and three different responses have been identified: 1) a return to a diatom composition found in the lake one hundred to several thousand years ago; 2) very small shifts in the diatom composition; or 3) a diatom composition previously not found in the lake. The latter response raised the question whether liming can cause an unnatural diatom community. A comparison of diatoms in surface sediment samples of 31 limed lakes with pre-industrial reference samples from 291 lakes showed that liming does not create an unnatural diatom composition. These results illustrate that the goals for liming were not reached in all of the limed lakes, and that paleolimnology can play an important role for assessments of acidification and liming. The comparative study also highlights the importance of designing monitoring programs that can produce reliable and long data series.

Given the results of the paleolimnological investigations, it is obvious that we cannot assume that the 19th century represented a natural or near natural state, and thus is a realistic reference conditions. Natural long-term lake development and previous land-use impacts need to be considered in defining reference conditions. Neither can we disregard the fact that humans always will impact nature. Although paleolimnological studies are time consuming, I believe that they could be simplified to the extent that paleolimnology could become a routine method for environmental management.

Place, publisher, year, edition, pages
Umeå: VMC, KBC, Umeå University, 2009. 14+4 papers p.
Acidification, Liming, European Water Framework Directive, Reference condition, Diatoms, Paleolimnology, Monitoring, Lake sediments
National Category
Earth and Related Environmental Sciences
Research subject
Earth Sciences with Specialization Environmental Analysis
urn:nbn:se:umu:diva-20583 (URN)978-91-7264-761-9 (ISBN)
Public defence
2009-04-24, KB3A9 (Lilla hörsalen), plan 3, KBC-huset, Umeå universitet, Umeå, 10:00 (English)
Available from: 2009-03-31 Created: 2009-03-23 Last updated: 2009-03-31Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Guhrén, MatildaBigler, ChristianRenberg, Ingemar
By organisation
Ecology and Environmental Science
In the same journal
Journal of Paleolimnology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 106 hits
ReferencesLink to record
Permanent link

Direct link