Effects of spring flood and water level draw-down on methane dynamics in the littoral zone of boreal lakes

Citation
S. Juutinen et al., Effects of spring flood and water level draw-down on methane dynamics in the littoral zone of boreal lakes, FRESHW BIOL, 46(7), 2001, pp. 855-869
Citations number
64
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Aquatic Sciences
Journal title
FRESHWATER BIOLOGY
ISSN journal
0046-5070 → ACNP
Volume
46
Issue
7
Year of publication
2001
Pages
855 - 869
Database
ISI
SICI code
0046-5070(200107)46:7<855:EOSFAW>2.0.ZU;2-X
Abstract
1. The annual dynamics of methane (CH4) in a temporarily flooded meadow, mi re bank, lacustrine sedge fen, temporarily and continuously inundated sedge (Carex sp.) and reed (Phragmites australis) marshes were studied from June to November in the humic mesoeutrophic Lake Mekrijarvi and in eutrophicate d parts of the mesotrophic Lake Heposelka in the southern part of East Finl and. The effects of water level and temperature on littoral CH4 fluxes were determined. Vegetation zonation along the moisture gradient, and associate d CH4 fluxes, were evaluated. 2. The CH4 flux increased along the moisture gradient from -0.2 to 14.2 mg CH4 m(-2) h(-1), and was highest in the permanently inundated marshes. The duration of anoxia in the sediment caused differences in the CH4 flux. Esti mated emissions for the period 1 June 30 September in continuously inundate d sparse reed and sedge marshes, drying sedge marsh, and lacustrine sedge f en were 13, 11 and 6 g CH4 m(-2), respectively. 3. In continuously inundated vegetation, the fluxes were highest in late Ju ly/early August. The seasonal CH4 flux pattern suggested that the fluxes we re regulated by the supply of organic matter during the course of the summe r and the water level. In the temporarily flooded zone, the seasonal CH4 fl ux dynamics was greatly affected by changes in the lake water level, the fl uxes being highest during the spring flood in early June.