Optical investigations of Estonian and Finnish lakes

Arst, Helgi; Mäekivi, S.; Kutser, T.; Reinart, Anu; Blanco-Sequeiros, Alberto; Virta, J.; Nõges, Peeter

doi:10.1111/j.1440-1770.1996.tb00064.x

Cited by 13 publications

(12 citation statements)

References 10 publications

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“…It must be noted that the disagreement between the change of temperature and C chl was observed also from July to October 1998, when the water temperature decreased remarkably, but C chl preserved rather high values during that period. The high values of chlorophyll a in autumn have also been observed in other lakes and at other times (Arst et al 1996, 1999).…”

Section: Resultssupporting

confidence: 71%

“…Here it is better to consider the data on Lake Ülemiste together with the respective results for other lakes. In 1992–1998, we studied 30 Estonian and Finnish lakes, the correlation analysis results for 1992–1997 (without Ülemiste) are published in Arst et al 1995, 1996 and 1999. The correlation ln z SD versus ln[ c *(400–700)] for these lakes (including Lake Ülemiste) is presented in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Optical and biological properties of Lake Ülemiste, a water reservoir of the city of Tallinn I: Water transparency and optically active substances in the water

Erm¹,

Arst²,

Trei

et al. 2001

Lakes & Reservoirs

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Optical and biological measurements were performed in Lake Ülemiste in the summer of 1997 (four measurement days), and from May to October in 1998 (12 measurement days). This kind of data, describing the type and amount of optically active substances in the water, phytoplankton characteristics, the underwater light field, and temperature–oxygen situation in the lake are necessary when estimating the ecological state of the lake. Lake Ülemiste is the main drinking water reservoir of Tallinn, the capital of Estonia. Phytoplankton abundance and biomass, chlorophyll a and suspended matter were determined from collected Lake Ülemiste water samples in the laboratory. Spectrophotometrical processing of the filtered and unfiltered water was carried out to describe the beam attenuation coefficient spectra and optical influence of yellow substance in the water. Vertical profiles of downwelling irradiance of the PAR (400–700 m) region of the spectrum (and from these data the averaged over depth diffuse attenuation coefficient) were determined. The relative transparency of the water was estimated by using a Secchi disk. Passive optical remote measurements were episodically made from aboard a boat. Results obtained confirmed that Lake Ülemiste is turbid (almost hypertrophic), comparable with most turbid lakes in Estonia (e.g. Lake Võrtsjärv) and Finland (Lake Tuusulanjärvi). Its chlorophyll a content varied within the range 13–121 mg m–3, phytoplankton biomass 3–107 mg L–1, phytoplankton abundance 65 000–999 000 mL–1, suspended matter 8–34 mg L–1, effective concentration of the yellow substance 6–30 mg L–1, diffuse attenuation coefficient of light in the PAR region 1.0–3.3 m–1 and a Secchi disk depth of 0.5–1.75 m. The temporal variation of the spatial averages of these parameters during 1998 was analysed. Almost all characteristics showed an increase from May to midsummer with a maximum in late July or in August (correspondingly the Secchi depth values were minimal in late summer). The amount of yellow substance was an exception, which was nearly constant during the observation period. The maximum level of chlorophyll a content in July and August 1998 markedly exceeded that in 1997, despite the fact that the summer of 1997 was sunny, but the summer of 1998 was cold and rainy. The correlative relationships between the different parameters were investigated together with the respective data for other lakes. They show that the data of Lake Ülemiste supplemented the correlation graph in the region of turbid lakes, whereby in all cases the correlation coefficient increased following the addition of Lake Ülemiste data. The highest correlation coefficient was obtained when light attenuation coefficient values were correlated with a sum of weighted concentrations of chlorophyll a, yellow substance and suspended matter (multiple regression analysis).

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Section: Resultssupporting

confidence: 71%

Section: Resultsmentioning

confidence: 99%

Optical and biological properties of Lake Ülemiste, a water reservoir of the city of Tallinn I: Water transparency and optically active substances in the water

Erm¹,

Arst²,

Trei

et al. 2001

Lakes & Reservoirs

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“…2. This shape is very typical of lake waters rich in yellow substance (Hickman et al 1984; Kirk 1994b; Arst et al 1996). Selective absorption of violet and blue light (400–500 nm) with depth, and also to some extent red light, have a great influence on the spectral distribution of PAR in Lake Ülemiste, resulting in a transmission peak at approximately 580–600 nm in the spectra of underwater light.…”

Section: Resultsmentioning

confidence: 95%

Optical and biological properties of Lake Ülemiste, a water reservoir of the city of Tallinn II: Light climate in Lake Ülemiste

et al. 2001

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Underwater light climate in strongly eutrophic Lake Ülemiste was studied by applying in situ measurements and model calculations. The attenuation of light in the waters of Lake Ülemiste is rather high, with a diffuse attenuation coefficient of photosynthetically active radiation, spectral region 400–700 nm (PAR) being 1.0–3.3 m–1. From the subsurface irradiance, only 3–13% reaches the depth of 1 m. However, in most cases, 1% from the irradiance just under the surface of water is available at the average depth (2.5 m) of the lake. A simple model is used for an approximate description of the temporal variation of underwater PAR at different depths. The initial data are the episodically determined values of the diffuse attenuation coefficient of PAR, Kd,PAR and the values of continuously recorded incident irradiance. Light is limiting phytoplankton growth in Lake Ülemiste only for a very short time each year: in early spring and late summer. The study should be continued to investigate the effect of artificially regulated influx and outflow of water and nutrients to toxic cyanobacteria blooms in this lake.

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“…No correction for the small-angle forward scattering was applied. However, the previous analysis of lakes data show, that c*(k) spectra are rather good indicators of water transparency and quality (Arst et al, 1996(Arst et al, , 1999.…”

Section: Measurements Of Oasmentioning

confidence: 95%

Optical Properties and Light Climate in Lake Verevi

Reinart

Arst²,

Pierson

2005

Hydrobiologia

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The optical properties and light climate during the ice-free period in the highly stratified Lake Verevi (Estonia) have been studied together with other lakes in same region since 1994. The upper water layer above the thermocline belongs to class ''moderate'' by optical classification of Estonian lakes but can turn ''turbid'' (concentration of chlorophyll a up to 73 mg m )3 and total suspended matter up to 13.2 g m )3 ) during late summer blooms. In the blue part of the spectrum, light is mainly attenuated by dissolved organic matter and in red part notably scattering but also absorption by phytoplanktonic pigments effect the spectral distribution of underwater light. Consequently, the underwater light is of greenish-yellow color (550-650 nm). Rapid change in optical properties occurs with an increase of all optically active substances close to thermocline (2.5-6 m). Optical measurements are often hampered beneath this layer so that modeling of the depth distribution of the diffuse attenuation coefficient is an useful compliment to field measurements. K d,PAR ranges from 0.8 to 2.9 m )1 in the surface layer, and model results suggest that it may be up to 5.8 m )1 in the optically dense layer. This forms a barrier for light penetration into the hypolimnion.

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Optical investigations of Estonian and Finnish lakes

Cited by 13 publications

References 10 publications

Optical and biological properties of Lake Ülemiste, a water reservoir of the city of Tallinn I: Water transparency and optically active substances in the water

Optical and biological properties of Lake Ülemiste, a water reservoir of the city of Tallinn I: Water transparency and optically active substances in the water

Optical and biological properties of Lake Ülemiste, a water reservoir of the city of Tallinn II: Light climate in Lake Ülemiste

Optical Properties and Light Climate in Lake Verevi

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