Nutrient balances and phytoplankton dynamics in two agriculturally loaded shallow lakes

Knuuttila, Seppo; Pietiläinen, Olli-Pekka; Kauppi, Lea

doi:10.1007/978-94-017-2460-9_32

Cited by 12 publications

(11 citation statements)

References 9 publications

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“…This was primarily a function of the differences in SS mobilization, which suggests that strategies for reducing the TP loads for this pastureland catchment setting should target those areas within the catchment that possess both high erosion potentials and high potentials for sediment delivery to the stream. Although PP is not as effective as DP in promoting short-term algal growth since only a portion of it is immediately available for biological uptake (Sharpley, 1993), PP presents a long-term risk to lake eutrophication as a result of the gradual release of soluble P from lake-bottom sediment (Knuuttila et al, 1994). Any enduring remedial strategy must also include, as a long-term goal, the reduction in soil P levels that act as a source for the hydrological transport.…”

Section: Discussionmentioning

confidence: 99%

A nested catchment approach for defining the hydrological controls on non-point phosphorus transport

Scanlon

Kiely

Xie

2004

Journal of Hydrology

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Section: Discussionmentioning

confidence: 99%

A nested catchment approach for defining the hydrological controls on non-point phosphorus transport

Scanlon

Kiely

Xie

2004

Journal of Hydrology

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“…During the period when most of the agricultural loading enters the surface waters in southern Finland (from October to April) the DRP concentration in lakes varies from 20-40 pg l-' and the pH is about 7 (Knuuttila et al, 1994). At pH 7 the EPC of the samples concentrated by filtration varied between 0 and 8 pg l-'.…”

Section: Bioavailability Of Dissolved Pmentioning

confidence: 99%

“…In many agriculturally loaded lakes DRP is utilized by algae almost completely (Knuuttila et al, 1994). Thus the DRP concentration in lakes becomes lower than the EPC, which makes the desorption of P possible.…”

Section: Bioavailability Of Dissolved Pmentioning

confidence: 99%

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Bioavailability of phosphorus in agriculturally loaded rivers in southern Finland

Ekholm¹

1994

Hydrobiologia

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The potential bioavailability of phosphorus in agriculturally loaded rivers of southern Finland was determined by an algal bioassay and the release of the potentially bioavailable particulate P was estimated by sorption studies. According to the bioassay 0 to 13.2 per cent (mean 5.1%) of the particulate P in river water samples was potentially bioavailable. Dissolved reactive P (DRP) in river waters appeared to be totally bioavailable whereas the dissolved unreactive P appeared not to be utilized by algae. In addition to river waters two lake sediment samples were also assayed. In these samples 0 and 2.6% of the P was bioavailable. The potential bioavailability of particulate P in agriculturally loaded rivers obtained in this study was lower than that reported in studies from other countries. The difference was assumed to arise partly from methodological factors and partly from the nature of the Finnish soils. The EPC (equilibrium phosphate concentration) values indicated that during the period when most of the agricultural loading enters the lakes in Finland, potentially bioavailable P is not released from the particles because of the relatively high DRP concentration in the receiving waters. However, during the algal production period the DRP concentration in lakes decreases below the EPC and potentially bioavailable particulate P is desorbed. The increase in pH during this period may further enhance the desorption of P.

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“…Although numerous studies have focussed on the amount, pathways, mechanisms and reduction of agricultural nutrient losses to aquatic systems (Särkkä, 1972;Kauppi, 1984;Turtola and Paajanen, 1995;Yli-Halla et al, 1995;Vuorenmaa et al, 2002;Koskiaho et al, 2003), relatively little information is available on the actual impact of these losses on lakes in Finland. The response of a specific lake to present and historical loads has been examined by Kukkonen and Tynni (1970), Kauppi et al (1988), Räsänen et al (1992), Salonen et al (1993), Knuuttila et al (1994), Ekholm et al (1997), Itkonen and Olander (1997), Räsänen et al (2004) and Krogerus and Ekholm (2003). However, with the exception of the survey of Kauppi et al (1990a,b) on the relationship between land-use and blue-green algal blooms, no large-scale studies have been conducted on general spatial and temporal trends in the water quality of agricultural lakes.…”

Section: Introductionmentioning

confidence: 99%

Agricultural Lakes in Finland: Current Water Quality and Trends

Ekholm

Mitikka

2006

Environ Monit Assess

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Agriculture is the largest source of nutrients into surface waters in Finland, and yet relatively little is known about the actual impact of the agricultural load on the state of lakes. We analysed the water quality data of 20 Finnish agricultural lakes and found that they had higher levels of nutrients, chlorophyll a and turbidity than did the other types of lakes (e.g. those receiving point-source load) in the national monitoring network (the Finnish Eurowaternet). Currently, six of the agricultural lakes can be classified as eutrophic and 14 as hypertrophic. Trend analysis (based on Kendall's tau-b) indicated that during 1976-2002 the water quality of the lakes either remained constant or showed signs of increasing eutrophication and elevated turbidity. Decreasing nutrient concentrations were found only in one intensively restored lake. In none of the lakes had the chlorophyll a concentration decreased. The results of the trend analysis are compatible with the recent finding that, despite vigorous efforts, the nutrient load from agriculture has not declined in Finland. Recovery of the most eutrophied agricultural lakes would call for a drastic reduction in the external nutrient load, possibly supplemented with in-lake restoration.

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Nutrient balances and phytoplankton dynamics in two agriculturally loaded shallow lakes

Cited by 12 publications

References 9 publications

A nested catchment approach for defining the hydrological controls on non-point phosphorus transport

A nested catchment approach for defining the hydrological controls on non-point phosphorus transport

Bioavailability of phosphorus in agriculturally loaded rivers in southern Finland

Agricultural Lakes in Finland: Current Water Quality and Trends

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