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The limnic ecosystems at Forsmark and Laxemar-Simpevarp. Site descriptive modelling SDM-Site

Abstract

The overall objective of this report is to provide a thorough description of the limnic ecosystems at both Forsmark and Laxemar-Simpevarp. This information may be used in the Safety Assessment and as a basis for the Environmental Impact Assessment. Three aims were set up for the report: 1) to characterize and describe the limnic ecosystems today and in the past in the Forsmark and Laxemar-Simpevarp areas and compare these ecosystems with limnic ecosystems in other areas; 2) to evaluate and visualize major pools, fluxes and sinks of elements within the limnic ecosystems; and finally 3) to describe human impact on the limnic ecosystems. The report includes a thorough description of the lakes and streams in Forsmark and Laxemar-Simpevarp and covers the following areas: catchment area characteristics, hydrology, climate, sediment characteristics, physical characteristics of streams, habitat distribution in lakes, biotic components, water chemistry, comparisons with other lakes and streams in the region, and a historical description. Ecosystem models for carbon and mass balances for a number of elements have been calculated to further improve the understanding of the lake ecosystems. Important processes for the safety assessment are described and evaluated in the report. The Forsmark regional model area contains more than  More>>
Authors:
Norden, Sara; Soederbaeck, Bjoern; [1]  Andersson, Eva [2] 
  1. Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)
  2. SWECO, Stockholm (Sweden)
Publication Date:
Nov 15, 2008
Product Type:
Technical Report
Report Number:
SKB-R-08-02
Resource Relation:
Other Information: 160 refs., figs., tabs.
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; RADIOACTIVE WASTE DISPOSAL; UNDERGROUND DISPOSAL; SITE CHARACTERIZATION; SURFACE WATERS; HYDROLOGY; AQUATIC ECOSYSTEMS; SAFETY ANALYSIS; LIMNOLOGY; CLIMATES; CARBON CYCLE; BENTHOS
OSTI ID:
951457
Research Organizations:
Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)
Country of Origin:
Sweden
Language:
English
Other Identifying Numbers:
Other: ISSN 1402-3091; TRN: SE0908125
Availability:
Also available from: http://www.skb.se/upload/publications/pdf/R-08-02del1webb.pdf (part 1) and http://www.skb.se/upload/publications/pdf/R-08-02del2webb.pdf (part 2); OSTI as DE00951457
Submitting Site:
SWDN
Size:
355 pages
Announcement Date:
Apr 24, 2009

Citation Formats

Norden, Sara, Soederbaeck, Bjoern, and Andersson, Eva. The limnic ecosystems at Forsmark and Laxemar-Simpevarp. Site descriptive modelling SDM-Site. Sweden: N. p., 2008. Web.
Norden, Sara, Soederbaeck, Bjoern, & Andersson, Eva. The limnic ecosystems at Forsmark and Laxemar-Simpevarp. Site descriptive modelling SDM-Site. Sweden.
Norden, Sara, Soederbaeck, Bjoern, and Andersson, Eva. 2008. "The limnic ecosystems at Forsmark and Laxemar-Simpevarp. Site descriptive modelling SDM-Site." Sweden.
@misc{etde_951457,
title = {The limnic ecosystems at Forsmark and Laxemar-Simpevarp. Site descriptive modelling SDM-Site}
author = {Norden, Sara, Soederbaeck, Bjoern, and Andersson, Eva}
abstractNote = {The overall objective of this report is to provide a thorough description of the limnic ecosystems at both Forsmark and Laxemar-Simpevarp. This information may be used in the Safety Assessment and as a basis for the Environmental Impact Assessment. Three aims were set up for the report: 1) to characterize and describe the limnic ecosystems today and in the past in the Forsmark and Laxemar-Simpevarp areas and compare these ecosystems with limnic ecosystems in other areas; 2) to evaluate and visualize major pools, fluxes and sinks of elements within the limnic ecosystems; and finally 3) to describe human impact on the limnic ecosystems. The report includes a thorough description of the lakes and streams in Forsmark and Laxemar-Simpevarp and covers the following areas: catchment area characteristics, hydrology, climate, sediment characteristics, physical characteristics of streams, habitat distribution in lakes, biotic components, water chemistry, comparisons with other lakes and streams in the region, and a historical description. Ecosystem models for carbon and mass balances for a number of elements have been calculated to further improve the understanding of the lake ecosystems. Important processes for the safety assessment are described and evaluated in the report. The Forsmark regional model area contains more than 20 permanent lakes and pools. All lakes are small and shallow, and are characterized as oligotrophic hardwater lakes. Calcareous soils in the area give rise to high calcium concentrations in the surface water, which in turn leads to high pH and low nutrient concentrations in water as phosphorus often co-precipitates with calcium. The shallow depths and moderate water colour permit photosynthesis in the entire benthic habitat of the lakes, and the bottoms are covered by dense stands of the macroalgae Chara sp. Moreover, many of the lakes also have a thick microbial mat (>10 cm), consisting of cyanobacteria and diatoms, in the benthic habitat. Fish in the lakes are dominated by species resistant to low oxygen concentrations, mainly due to poor oxygen conditions during the winter. The streams in Forsmark are all very small, and long stretches of the streams are dry during summer. The downstream parts of some of the streams may function as passages for migrating fish, and extensive spawning migration between the sea and a downstream lake has been observed. Human activities in the area have affected the limnic ecosystem, and large parts of the streams in the Forsmark area consist of man-made ditches. Moreover, one of the lakes has been lowered and one has been divided into two basins. The ecosystem carbon models for the Forsmark area show that the lakes that contain a microbial mat have larger primary production than respiration, and thus show a positive net ecosystem production (NEP). In lakes that lack a microbial mat, respiration is similar in magnitude as primary production and net ecosystem production is close to zero. Carbon mass balance models for the Forsmark lakes indicate, in accordance with the ecosystem models, that the larger lakes (with a microbial mat) in the area have a positive NEP. However, in contrast to the ecosystem models, the mass balance models indicate that the smaller lakes in the area have negative NEP, regardless of the occurrence of a microbial mat. A low proportion (7-10%) of the carbon incorporated into primary producers in the lake is transported upwards in the food web, and instead most carbon is consumed by bacteria in the form of DOC and POC. The mass balances for a number of elements in Forsmark lakes show that the proportions of different fluxes to and from the lakes are dependent on lake size and position in the catchment, but also on the specific properties of the different elements. The Laxemar-Simpevarp lakes are small and all but one are characterized as brown-water lakes. The lakes have moderate phosphorus concentrations, whereas the concentrations of nitrogen and dissolved organic carbon tend to be high. Because of the brownish water, light penetration is poor and the depth of the photic zone is generally small. In accordance, macrophyte coverage in the lakes is small and biota is dominated by heterotrophic organisms, particularly bacteria. Perch is the predominant fish species in numbers, as well as in weight, in the lakes in the area. Most of the streams in the Laxemar-Simpevarp area are small with mostly calm or slowly flowing water and many of the streams have dry sections in the summer. Most lakes in the Laxemar-Simpevarp area are affected by human activities; the water level in most lakes has been lowered, and one lake, Soeraamagasinet, was originally a sea bay but was dammed in order to ensure freshwater reserves to the nuclear power plant. Water is pumped from Laxemaraan to Soeraamagasinet in order to maintain the available water storage in the lake.}
place = {Sweden}
year = {2008}
month = {Nov}
}