Factors behind the variability of phosphorus accumulation in Finnish lakes

Abstract

Purpose. Phosphorus retention (TPacc) is one of the major water quality regulators in lakes. The current study aimed at ascertaining the specific lake characteristics regulating TPacc. Moreover, we were interested whether NAO (North Atlantic Oscillation), a proxy of climatic forcing, can explain variability in TPacc, 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 TPacc (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 TPacc. Results and discussion. Lake characteristics explained the bulk of TPacc variability. The most influential factors (positive drivers) behind TPacc 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 TPacc. 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 TPacc 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.

Impacts of a deep reactive layer on sedimentary phosphorus dynamics in a boreal lake recovering from eutrophication

“…The exponential increase in sedimentation rate observed with increasing water depth (Fig. 3d) is consistent with earlier studies reporting intensive sediment focusing into the deeps of Enonselka ¨(e.g., Nyka ¨nen et al, 2010;Niemisto ¨et al, 2012;Tammeorg et al, 2018). This phenomenon strongly influences the spatial distribution of P burial (Fig.…”

Windows into the past: lake sediment phosphorus trajectories act as integrated archives of watershed disturbance legacies over centennial scales

“…These results are consistent with previous studies that report the link between external P loading and morphology on P accumulation in lakes. For instance, elevated accumulation of P sed in smaller lakes was also reported in Finnish (Tammeorg et al 2018) and other European lakes (Keatley et al 2011). Lakes with higher W:L area experience greater watershed inputs per unit lake area (Schindler 1971) that potentially leads to higher sediment P accumulation.…”

“…These studies have mostly focused on understanding the drivers of sediment P dynamics in individual lakes (Engstrom et al 2006, Otu et al 2011, Levine et al 2018. Regionalscale studies that explore P trajectories are limited, albeit a few exist, such as a study across two dozen lakes in Finland (Tammeorg et al 2018), or a range of shallow lakes in Southern Florida, USA (Kenney et al 2016). Using a meta-analysis approach, Carey and Rydin (2011) show that P burial patterns are representative of lake trophic status, alluding to the linkage between lake sediment and watershed inputs.…”

Adsorption-Release Characteristics of Phosphorus and the Community of Phosphorus Accumulating Organisms of Sediments in a Shallow Lake

“…Fe/Al-P is quickly released from sediments under specific redox, pH, and other conditions, and the released P then becomes bio-available. In contrast, Ca-P is a relatively stable P and typically remains biologically unavailable [39]. The optimum adsorption rate was calculated using the double-constant rate model and the modified Elovich model.…”