Factors behind the variability of phosphorus accumulation in Finnish lakes

• Published in: Journal of soils and sediments Vol. 18; no. 5; pp. 2117 - 2129
• Main Authors: Tammeorg, Olga, Haldna, Marina, Nõges, Peeter, Appleby, Peter, Möls, Tõnu, Niemistö, Juha, Tammeorg, Priit, Horppila, Jukka
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2018; Springer Nature B.V
• Subjects: Anoxia; Anoxic sediments; Atmospheric forcing; autumn; Bottom water; Catchment areas; Climate change; Climate change models; Climate models; Components; Cores; Dating techniques; Dynamics; Earth and Environmental Science; Environment; Environmental Physics; Inflow; Lakes; Mineralization; Modelling; North Atlantic Oscillation; Ocean-atmosphere system; Organic matter; Phosphorus; Radiometric dating; radiometry; Regulators; Residence time; Retention; Sec 2 • Physical and Biogeochemical Processes • Research Article; Sediment; Sediments; Soil Science & Conservation; Stability; Variability; Water column; Water depth; Water inflow; Water quality; Water temperature; Watersheds; Lake characteristics; Lakes; NAO; Phosphorus retention; Phosphorus accumulation rate
• ISSN: 1439-0108; 1614-7480
• DOI: 10.1007/s11368-018-1973-8

Purpose Phosphorus retention (TP acc ) is one of the major water quality regulators in lakes. The current study aimed at ascertaining the specific lake characteristics regulating TP acc . Moreover, we were interested whether NAO (North Atlantic Oscillation), a proxy of climatic forcing, can explain variability in TP acc , additionally to that ascribed to lake characteristics. Materials and methods Sediment cores were obtained from 21 Finnish lakes, subject to radiometric dating and measurements of TP concentrations. Principal components (PCs) were generated using lake characteristics that are usually included into the modelling of TP acc (e.g. lake area, lake depth, catchment area, P inflow) but also the parameters that the classical models usually missed (e.g. anoxic factor). We used significant principal components (PCs), specific combinations of lake characteristics and monthly NAO values as predictors of TP acc . Results and discussion Lake characteristics explained the bulk of TP acc variability. The most influential factors (positive drivers) behind TP acc included PC1 (representing mainly deep lakes), PC2 (small lakes with high levels of anoxia and water column stability), PC3 (productive lakes with large catchment area and short water residence time), PC4 (lakes with high water column stability, low anoxic factor and relatively high sediment focusing) and PC5 (lakes with high levels of P inflow, anoxia and long water residence time). Additionally, we found a potential negative effect of NAO in October on the annual TP acc . This NAO was significantly positively related to temperatures in surface and near-bottom water layer (also their difference) in autumn, suggesting the possible implications for the internal P dynamics. Increased mineralization of organic matter is the most likely explanation for the reduced TP acc associated with NAO-driven water temperature increase. Conclusions The analysis presented here contributes to the knowledge of the factors controlling P retention. Moreover, this spatially and temporally comprehensive sediment data can potentially be a valuable source for modelling climate change implications.