Internal Loading of Phosphorus from Bottom Sediments of Two Meso-eutrophic Lakes Article Swipe
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· 2019
· Open Access
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· DOI: https://doi.org/10.1007/s41742-019-00167-y
· OA: W2910729158
The aim of the study was to determine the seasonal and spatial variability of phosphorus release from bottom sediments of two lakes in Poland (Wielkopolska Region): Lusowskie Lake and Prawe Lake. The comparison of results from these two lakes could have been reliably made, because they were characterized by a similar trophic state (meso-eutrophic), were located in the same climatic zone, and were examined at the same time but differed in terms of morphometry (area, depth, and shape) as well as land use of catchment area. These dimictic lakes were characterized by hypolimnetic oxygen deficits in summer. The internal loading of phosphorus was analysed on the basis of ex situ experiments with intact cores of bottom sediments sampled at two stations, situated in the profundal (the deepest place in the lake) and in the littoral (2.0 m depth). The results indicated that a higher phosphorus load was released from bottom sediments in the profundal zone than in the littoral zone of both lakes. Phosphorus release from the profundal zone was twofold higher in Prawe Lake than in Lusowskie Lake. It reached 2.6 mg P m−2 d−1 in spring and winter in the larger and deeper Lusowskie Lake, compared to 6.04 mg P m−2 d−1 in autumn in the smaller and shallower Prawe Lake. In the littoral zone, phosphorus release reached 1.67 mg P m−2 d−1 and 0.16 mg P m−2 d−1 in both lakes, respectively. Differences in phosphorus internal loading between the lakes were due to differences in the stability of thermal stratification, time of water mixing and oxygen concentration in the depth profile of the lake.
