Ergebnisse der limnologischen Untersuchungen der Oberengadiner Seen

Bosli-Pavoni, Marianne

doi:10.1007/bf02504004

Cited by 9 publications

(7 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Concomitant with distinct changes in sediment colour, diatom assemblages point to progressively increasing TP levels ( Figure 8) that are culminating towards the early 1960s (>50 µg/l). DI-TP during this period corresponds well with observational data, as a TP concentration of 43 µg/l is reported at the end of the 1960s (Bosli-Pavoni, 1971). At the present-day, diatoms suggest TP levels that are in good agreement with observational data (~20 µg/l).…”

Section: Tp Inference Model and Quantitative Reconstructionssupporting

confidence: 87%

“…A decreasing diatom diversity as caused by nutrient enrichment is also observed in lakes with differing catchment properties (eg, Lotter, 1998Lotter, , 2001bRusak et al, 2004) and experimental studies (Proulx et al, 1996). Since AD 1960, sewage input to the lake was systematically reduced, for example by directing wastewater from the town of St Moritz to the River Inn downstream of Lej da San Murezzan in AD 1969, and the establishment of regional sewage treatment plants at the beginning of the 1970s (Bosli-Pavoni, 1971;Züllig, 1982a). These wastewater management measures led to a substantial reduction of TP concentrations, with positive effects on diatom diversity.…”

Section: Variability and Recovery Of Diatom Assemblages In Relation Tmentioning

confidence: 97%

“…has a maximum depth of 44 m, an area of 0.8 km 2 and a water residence time of <1 yr (Züllig, 1982a;Schelske et al, 1987). The lake is ice-covered from January to May (ice-break up dates have been recorded since AD 1832; Livingstone, 1997), followed by a stable summer stratification from June through November (Bosli-Pavoni, 1971) causing hypolimnetic anoxia. The TP concentration (depth-weighted average value for the entire water column) in Lej da San Murezzan is 15 µg/l and indicates mesotrophic nutrient conditions, the lake-water pH is 6.8 (both measured 27 August 2002; Bigler et al, 2006).…”

Section: Sitesmentioning

confidence: 99%

See 2 more Smart Citations

Quantifying human-induced eutrophication in Swiss mountain lakes since AD 1800 using diatoms

et al. 2007

View full text Add to dashboard Cite

Sedimentary diatom assemblages from three lakes in the southeastern Swiss Alps were analysed at high temporal resolution since AD 1800. Altered land-use patterns, increasing population and exploitation through tourism are clearly reflected in annually laminated sediments of Lej da San Murezzan (Lake St Moritz) and Lej da Silvaplauna (Lake Silvaplana). Diatom assemblages originally dominated by Cyclotella taxa are replaced by taxa indicating higher total phosphorus (TP) concentrations, such as Asterionella formosa, Fragilaria crotonensis and Stephanodiscus parvus. In Lej da la Tscheppa, located well above the treeline in a catchment that was hardly exposed to human impact, Cyclotella comensis prevails throughout the entire sediment sequence. Quantitative estimates of past TP concentrations were inferred using a newly developed regional diatom-TP inference model based on 119 modern samples. In Lej da la Tscheppa diatoms imply stable, low TP concentrations (~10 µg/l), which can be considered as natural background concentration. Elevated TP levels are inferred for Lej da San Murezzan (max. 60 µg/l) since AD 1910 and for Lej da Silvaplauna (max. 40 µg/l) since AD 1950, corroborated by changes in sedimentary biogenic silica concentration and organic carbon content. Since ~AD 1970 improved waste water management led to a considerable reduction in TP loading in Lej da Silvaplauna and Lej da San Murezzan.

show abstract

Section: Tp Inference Model and Quantitative Reconstructionssupporting

confidence: 87%

Section: Variability and Recovery Of Diatom Assemblages In Relation Tmentioning

confidence: 97%

Section: Sitesmentioning

confidence: 99%

See 1 more Smart Citation

Quantifying human-induced eutrophication in Swiss mountain lakes since AD 1800 using diatoms

et al. 2007

View full text Add to dashboard Cite

show abstract

“…Conductivity ranges from 80 to 105 µS cm -1 and the water hardness is 3.2 -3.9 °fr. H. (Bosli-Pavoni 1971). Maximum water depth is 71 meters and the mean residence time is about 2 years (LIMNEX 1994).…”

Section: Study Areamentioning

confidence: 99%

The last 1300 years of environmental history recorded in the sediments of Lake Sils (Engadine, Switzerland)

Blass

Anselmetti

Grosjean

et al. 2005

Eclogae geol. Helv.

View full text Add to dashboard Cite

Proglacial Lake Sils is located in the Upper Engadine (south-eastern Swiss Alps) at 1800 m a.s.l. and is the uppermost of four lakes in the valley. A highresolution seismic survey combined with geophysical and chemical data of 22 short sediment cores, and 137 Cs, 210 Pb, and 14 C AMS dating provide insight into the sedimentological development of the lake during the last 1300 years. The deposits consist of diffusely laminated clayey silts. In contrast to nearby Lake Silvaplana, no varves could be detected. Sedimentation rates are on average 1.1 mm per year (40 mg cm -2 a -1 ) which is much lower than in the adjacent Engadine lakes. The most prominent sediment feature is a turbidite that was deposited around cal AD 700, has a thickness of up to more than 6 metres and a total estimated volume of 6.5*10 6 m 3 , which is more than the total cumulated sediment mass deposited since that time (4.5 * 10 6 m 3 ).The sediments deposited after around AD 1880 show higher contents of organic carbon (Corg) and biogenic silica (bSi), which suggests enhanced primary production due to increasing tourism in the area and subsequent higher nutrient supply to the lake. Sediments with distinctly lower Corg and bSi concentrations, but with larger grain-size medians and higher mica concentrations were accumulated between AD 1500 and 1880. These features are related to a late period of the 'Little Ice Age' when major regional glacier advances occurred. ZUSAMMENFASSUNGDer von Gletscherwasser gespiesene Silsersee liegt im Oberengadin in den Schweizer Südost-Alpen auf 1800 m ü. M. und ist der Oberste in der Engadiner Seen-Kette. Aufgrund von hoch auflösenden, seismischen Daten und ungefähr zwei Dutzend Sedimentkernen, datiert anhand von 137 Cs, 210 Pb und AMS 14 C, mit anschliessenden geophysikalischen und geochemischen Analysen, kann hier eine breite Datenbasis präsentiert und die sedimentologische Entwicklung des Sees in den letzten 1300 Jahren aufgezeigt werden. Die Ablagerungen sind diffus laminiert und bestehen hauptsächlich aus tonigem Silt. Varven, wie im benachbarten Silvaplanersee, wurden keine erkannt. Die Sedimentationsrate liegt mit 1.1 mm pro Jahr (40 mg cm -2 a -1 ) ungefähr eine Grös-senordnung tiefer als in den anderen Engadiner Seen. Ein bis zu 6 Meter mächtiger Turbidit wurde um AD 700 abgelagert. Das geschätzte Volumen von 6.5*10 6 m 3 liegt wesentlich über dem seither abgelagerten Volumen von 4.5 * 10 6 m 3 .Seit ungefähr AD 1880 wurde in den Sedimenten markant höhere Werte an organischem Kohlenstoff (Corg) und biogenem Silizium (bSi) gemessen. Dies wird auf die seit anfangs des letzten Jahrhunderts stark angestiegenen Touristenzahlen zurückgeführt, was ein erhöhtes Angebot an Nährstoffen im See verursacht hat. In der Periode von ca. AD 1500 -1880 wurden einerseits deutlich tiefere Konzentrationen an bSi und Corg, andererseits besser sortierte und gröbere Sedimente festgestellt und zudem erhöhte Glimmer Werte gemessen. Diese Veränderungen werden mit einer späten Phase der 'kleinen Eiszeit' in Verbindung gebrach...

show abstract

“…The dimictic lake is thermally stratified during summertime (Bosli-Pavoni, 1971) and has a depth of 78m. Its primary sources are the outflow of adjacent Lake Sils in the southwest and the Fedocla, which drains the southern part of the catchment.…”

Section: Introductionmentioning

confidence: 99%

Holocene glacial activity and climatic variations in the Swiss Alps: reconstructing a continuous record from proglacial lake sediments

1994

View full text Add to dashboard Cite

Cores recovered from proglacial Lake Silvaplana (Swiss Alps) were investigated to examine the influence of Holocene glaciers on lacustrine sedimentation. During times of glacial activity in the catchment the sedimentation in the lake is dominated by the input of silt and clay-sized material delivered by glacial meltwaters. The deposition of fine-grained material and the formation of varves reflect the existence of glaciers in the catchment and can therefore be used for the reconstruction of glacial history. Sedimentation rates are up to nine times higher in the varved than in the non-varved sediments, indicating significantly higher erosion rates under glaciated catchment conditions. Glacial varves were deposited in Lake Silvaplana during glacial retreat in the latest Pleistocene and early Holocene until 9400BP. Non-varved deposits having a higher organic content and coarser grainsizes accumulated at lower rates when glacial activity was absent or negligible within the catchment between 9400 and 3300 BP. The continuous deposition of varves after 3300 BP indicates that Neoglaciation provided glacial cover for part of the catchment since then. Long-term variation in varve thickness is interpreted as being controlled by the size of the glaciers in the catchment. Maximal varve thicknesses are observed from AD 1790 to 1870. Since the changes in glacial activity for this area seem to be mainly controlled by temperature rather than precipitation, we suggest that the entire lacustrine sediment record of Lake Silvaplana reflects relative changes of summer air temperature during the Holocene.

show abstract

Ergebnisse der limnologischen Untersuchungen der Oberengadiner Seen

Cited by 9 publications

References 2 publications

Quantifying human-induced eutrophication in Swiss mountain lakes since AD 1800 using diatoms

Quantifying human-induced eutrophication in Swiss mountain lakes since AD 1800 using diatoms

The last 1300 years of environmental history recorded in the sediments of Lake Sils (Engadine, Switzerland)

Holocene glacial activity and climatic variations in the Swiss Alps: reconstructing a continuous record from proglacial lake sediments

Contact Info

Product

Resources

About