Contributions of DOC from surface and groundflow into Lake Võrtsjärv (Estonia)

Hydrological changes have the greatest impact on shallow lakes where they alter the water volume and lake depth noticeably. Dissolved organic carbon (DOC), which is markedly affected by hydrological factors, has an important role in many biogeochemical processes. The DOC load supplied to Lake Võrtsj...

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Bibliographic Details
Published in:Hydrobiologia 2008-03, Vol.599 (1), p.213-220
Main Authors: Tamm, Toomas, Nõges, Tiina, Järvet, Arvo, Bouraoui, Faycal
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
Biogeochemistry
Biological and medical sciences
Biomedical and Life Sciences
Climate change
Ecology
Ells 2007
Fresh water ecosystems
Freshwater & Marine Ecology
Fundamental and applied biological sciences. Psychology
General aspects
Groundwater flow
Hydrology
Lakes
Life Sciences
Synecology
Zoology
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Summary:Hydrological changes have the greatest impact on shallow lakes where they alter the water volume and lake depth noticeably. Dissolved organic carbon (DOC), which is markedly affected by hydrological factors, has an important role in many biogeochemical processes. The DOC load supplied to Lake Võrtsjärv, the second largest lake in Estonia, was studied on the scale of the subcatchments discharging into the lake. Daily discharges and biweekly or monthly DOC concentrations were measured close to the river outlets over the years 1990-2002. The stream flow data were separated into groundflow and surface flow by applying local minimum and recursive digital filtering methods. Constituent load estimation software, LOADEST, was used to estimate DOC concentrations and load. LOADEST performed well for three of the four rivers. The total estimated DOC load to Võrtsjärv from all four main rivers varied from 1,320 to 4,934 t year-¹. The average annual load over the 13-year period was 3,265 t year-¹ or 1.18 g C m-² year-¹. Baseflow separation analysis indicated that the DOC load originating from groundflow contributed 79% and 69% of the total load according to the digital filter and local minimum methods, respectively. The results of our study demonstrate the utility of linking the rating-curve method and baseflow separation to assess the allochthonous DOC load to Võrtsjärv both currently and under changing climatic conditions.
ISSN:0018-8158
1573-5117
DOI:10.1007/s10750-007-9189-8