Sediment phosphorus mobility in Võrtsjärv, a large shallow lake: Insights from phosphorus sorption experiments and long-term monitoring
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Kuupäev
2022
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Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Elsevier
Abstrakt
Sediment phosphorus (P) recycling is one of the key issues in lake water quality management. We studied sediment P
mobility in Võrtsjärv, a large shallow lake in Estonia using both sorption experiments and long-term (1985–2020)
monitoring data of the lake. Over the years studied, the lake has undergone a decline in external phosphorus loading
(EL), while no improvement in phytoplankton indicators was observed.
The results of the sorption experiments revealed that it may be successfully used as a tool to determine P forms involved
in P retention, as up to 100%of the P fromthe water column was detected in sediments. Incubation of wet sediment
is preferred to dry because of the sensitivity of organic P to desiccation. In the sediments of Võrtsjärv, the labile P
(Lab-P) and iron bound (Fe-P) fractions are the major forms of the mobile pool that supply internal P load as sediment
released P. The internal P load calculated from summer total P (TP) increases (ILin situ) in the water column was on average
42%, but could reach 240% of EL at extreme environmental conditions. ILin situ was correlated with the active
area, which resembles the area involved in redox-related P release in polymictic lakes, and with the mean bottom
shear stress in summer. ILin situ showed a similar decreasing pattern as the external P load over the years
1985–2020, and was likely driven by the decrease of the pool of releasable P. Similarly, the decreases in sediment loading
by P retention in our P sorption experiment were associated with decreases in the concentration of the potentially
mobile P forms (mainly Lab-P and Fe-P). These results show that changes in external P loading can successfully control
internal P loading and are useful in water quality management of large lakes.
We acknowledge the Estonian Research Council grants PRG709 and PRG1167, also European Union's Horizon 2020 research and innovation programme (project TREICLAKE) under grant agreement No 951963 for providing financial support for the project.
We acknowledge the Estonian Research Council grants PRG709 and PRG1167, also European Union's Horizon 2020 research and innovation programme (project TREICLAKE) under grant agreement No 951963 for providing financial support for the project.
Kirjeldus
Received 11 January 2022; Received in revised form 6 March 2022; Accepted 10 March 2022; Available online 17 March 2022; Editor: Jay Gan
Märksõnad
internal phosphorus loading, external loading, P sorption experiments, redox-related release, active phosphorus release area, sediment resuspension, Võrtsjärv, articles