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Causes of loading the water of the eutrophic Lake Jagielek with nitrogen and phosphorus compounds under the meteorological conditions of Olsztyn Lakeland

100%

Szymczyk S., Glinska-Lewczuk K.

Journal of Elementology

2007

tom 12

nr 4

347-361

The causes of the eutrophication of Lake Jagiełek, situated around 6 km south-west of Olsztyn, were investigated in the hydrological years 1998-2004. The catchment area of this water body is situated in the watershed zone of the Łyna and Pasłęka rivers. The lake is subject to advanced eutrophication. As regards precipitation amount, the analysed period consisted of three dry years, two normal years and one wet year. Due to the occurrence of three successive dry years and higher evaporation resulting from increased air temperatures (by 0.5°C on average), the lake shallowed with periodic exposure of bottom sediments in the shoreline zone. The periodic exposure and inundation of sections of the lake bottom has led to intense mineralization of bottom sediments. This process contributes to secondary contamination of surface water with mineral substances, mainly nitrogen and phosphorus compounds. The investigated water body is situated in a watershed zone and is characterised by low and stable electrolytic conductivity (113 µS·cm-1 on average) and low pH of water (6.72 on average) which periodically reaches 4.70. The concentration levels of biogenic elements (nitrogen and phosphorus compounds) are subject to seasonal fluctuation. Relatively high concentrations of N-NO3 (1.25 mg dm-3 on average) were observed in the winter and spring, while low levels of this compound (0.18 mg·dm-3 on average) were reported in the summer and autumn. P-PO4 concentrations were marked by a growing trend from 0.26 mg· dm-3 on average in the spring to 0.70 mg·dm-3 on average in the summer. A high water load with biogenic elements, whose concentrations significantly exceeded the allowable and dangerous levels of N and P according to Vollenweider’s criteria, speeded up the eutrophication process and stimulated the gradual self-decline of the entire ecosystem. The restoration of ecological balance in the surveyed.

Ograniczanie wyników

1 Journal of Elementology

1 Glinska-Lewczuk K.

1 Szymczyk S.

1 2007

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Causes of loading the water of the eutrophic Lake Jagielek with nitrogen and phosphorus compounds under the meteorological conditions of Olsztyn Lakeland