Phosphorus flux in Lake Peipsisensu stricto, Eastern Europe

Abstract

Phosphorus distribution in sediments and monitoring data from Lake Peipsi sensu stricto (s.s.) were used to elucidate the distribution of P fractions in the lithological and geochemical composition of the lake's sediments. The composition of P fractions in the sediment cores was rather constant in layers with porosity lower than 88%. The decay of biota during the compression and genesis of sediments leading to the liberation of P to interstitial water and its further diffusion along the concentration gradient towards the sediment-water surface are directed by environmental conditions. During phytoplankton blooms the release of P fractions from sediments may be as high as 875 tonnes of P in Lake Peipsi s.s. Calculations show that the average annual total P accumulation in Lake Peipsi s.s. is ca 270 mg m -2 y -1 .

Pool of mobile and immobile phosphorus in sediments of the large, shallow Lake Peipsi over the last 100 years

“…1b; 1,830 km 2 , i.e. ca 70% of the total bottom area of L. Peipsi s.s.) was taken into account following and Punning and Kapanen (2009).…”

“…The neutral salt solution extracted more P (NaCl-P) than the extraction with NH 4 Cl according to the modified Hieltjes and Lijklema (1980) method used in previous research of the P depositions in L. Peipsi (Kapanen 2008;Punning and Kapanen 2009). In previous studies the sediments were dried, which could cause degradation of easily degradable organic P compounds, increasing the NaCl-iP fraction (Lukkari 2008).…”

“…It is pointed out by many researchers that a typical exponential increase of the P content in surface layers of lake sediment cores does not always mark an increasing human-induced P load, but is a result of a comprehensive increase of sediment porosity (Perrone et al 2008). In L. Peipsi, where due to wind, wave action and internal currents the thermal and oxygen stratification are weak and sediments are highly cohesive, the depth of active layers can be preliminarily estimated to reach the depth of 88% water content (Punning and Kapanen 2009). In the current study, the sediment water content reached 89%, which means that also deep layers of the investigated profiles could take part in the active processes related to the P internal load.…”

“…While the external loading of Lake Peipsi sensu stricto (s.s.) has been extensively studied (Mourad et al 2006;Loigu et al 2008;Buhvestova et al 2011), comparatively few studies exist on the phosphorus release from sediment. The P flux at the sedimentwater interface is far from negligible and should be taken into account in lake management activities of L. Peipsi s.s. (Punning and Kapanen 2009).…”

“…Internal nutrient loading from lake sediments is known to affect the lake's trophic status and can substantially delay the recovery of its ecosystems to reduced external loading (Marsden 1989;Søndergaard et al 2003;Jeppesen et al 2005;Nõges et al 2007;Punning and Kapanen 2009). Understanding the size and availability of the nutrient pools in the sediments is therefore of critical importance in predicting how and when lake ecosystems will respond to changes in external loading (Nürnberg 1984;Marsden 1989;Lijklema et al 1993;Ramm and Scheps 1997;Gonsiorczyk et al 1998;Wu et al 2001;Zhou et al 2001;Kaiserli et al 2002;Spears et al 2007;Zhou et al 2008;Simon et al 2009).…”