Phosphorus retention as a function of external loading, hydraulic turnover time, area and relative depth in 54 lakes and reservoirs

Abstract

We analysed phosphorus retention as a function of external loading, hydraulic turnover time, area and relative depth on the basis of published data from 54 lakes and reservoirs in different climate regions around the world. Our analysis demonstrated that reservoirs and lakes that received higher areal loading of phosphorus (TP in ) also retained more P per m 2 but the proportion of the external P loading retained in the waterbody (retention coefficient, R P ) remained generally independent of TP in . The waterbodies with longer hydraulic residence times (T R ) retained larger proportions of external P and the correlation between R P and T R was much stronger in lakes with areas larger than 25 km 2 than in the whole data set. TP in and T R together determined 78% of the variation in R P in large lakes. We also partially confirmed our hypothesis that waterbodies with bigger relative depths (Z R ) retain more of the external phosphorus than larger and shallower waterbodies with lower Z R . The hypothesis was, however, validated only for lakes larger than 25 km 2 and for those with T R \0.3 year, where R P increased significantly with increasing Z R . In stratified lakes, increasing relative depth correlated with reduced P retention capacity, demonstrating the complex nature of phosphorus biogeochemistry in lake ecosystems.

Estimating internal P loading in a deep water reservoir of northern China using three different methods

“…According to the law of conservation of mass, P entering lakes is either directly deposited in the sediment or flows out from the reservoir. The results showed that P retention was positively related with inflow P load, in accordance with previous reports (Koiv et al 2011). Parts of the retained P would be buried as a permanently immobilized P fraction, whereas other parts would be mobile P, susceptible to releasing PO 4 3− to the overlying water.…”

Global phosphorus retention by river damming

“…As shown in Fig. S1, the modelpredicted R TP and R RP values exhibit positive trends with the hydraulic residence time, τ r , as expected from the literature (28)(29)(30). The trends are fitted to the classic Vollenweider model for P sequestration in lakes (Eq.…”

“…P retention in lakes and reservoirs correlates with the hydraulic residence time (τ r ) (28)(29)(30). Accordingly, τ r explains more than 45% of the variability of the R TP and R RP values generated by 6,000 Monte Carlo iterations of the P mass balance model.…”

High-frequency metabolism study in a large and shallow temperate lake reveals seasonal switching between net autotrophy and net heterotrophy

“…The Table 2 Parameters of the sinusoids fitted to the monthly mean values of gross primary production (GPP fit ), community respiration (R fit ), net ecosystem production (NEP fit ), daily solar irradiance (Q fit ) and daily surface water temperature (T fit ) in Lake Võrtsjärv The best model was selected with the stepwise procedure in Statistica 8.0 (StatSoft Inc., 1984-2007. Parameters are listed in order of decreasing importance, according to their t value (1998) mean depth of lakes per se had no significant effect on the auto-to-heterotrophy balance, whereas the relative depth, which is the maximum depth of a lake as a percentage of mean diameter (Wetzel, 2001) and characterises the potential of thermal stratification (Escobar et al, 2009;Tiberti et al, 2010) and phosphorus retention (Kõiv et al, 2011), had a significant impact towards heterotrophic conditions (decrease of GPP/R ratio) and a tendency towards lower NEP. Obviously, the trend of relatively deeper lakes being more heterotrophic can be attributed to stronger thermal stratification in these lakes, which leads to phosphorus depletion in the epilimnion during the growing season.…”