## 3 Results
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Treatment**} & \multicolumn{3}{c}{**OP Removed**} \\ \cline{2-4}  & **[mg PO\({}_{\textbf{4}}\)\({}^{\textbf{3-}}\)]** & **[mg PO\({}_{\textbf{4}}\)\({}^{\textbf{3-}}\) cm\({}^{\textbf{-2}}\)]** & **[mg PO\({}_{\textbf{4}}\)\({}^{\textbf{3-}}\) g\({}^{\textbf{-1}}\)]** \\ \hline \hline \multicolumn{4}{c}{**1 week**} \\ \hline Laminates & 25.8 & 0.017 & 7.2 \\ \hline Modules & 23.4 & 0.032 & 0.1 \\ \hline \multicolumn{4}{c}{**6 weeks**} \\ \hline Laminates & 21.7 & 0.014 & 6.0 \\ Modules & 59.8 & 0.081 & 0.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The OP removal during incubation calculated based on the OP concentration difference between the control mesocosm (no treatment) and treatment using laminates and modules. OP mass was corrected for the water volume reduction due to sampling. mg PO\({}_{\textbf{4}}\)\({}^{\textbf{3-}}\) stands for the total mass of the OP removed from the lake water; mg PO\({}_{\textbf{4}}\)\({}^{\textbf{3-}}\) cm\({}^{\textbf{-2}}\) indicates OP mass removed per unit of surface area of the calcite layer exposed in the mesocosm while mg PO\({}_{\textbf{4}}\)\({}^{\textbf{3-}}\) g\({}^{\textbf{-1}}\) indicates the OP mass removed by unit mass of calcite. Figure 5: OP availability in the lake water during incubation experiment: (**a**) OP concentration (mg PO\({}_{\textbf{4}}\)\({}^{\textbf{3-}}\) L\({}^{\textbf{-1}}\)); (**b**) OP balance (mg PO\({}_{\textbf{4}}\)\({}^{\textbf{3-}}\)) calculated as a change in the total OP mass present in the lake water at the beginning of the experiment; lake water volume was corrected for the reduction due to sampling. Day 0 in chart (**a**) indicates initial conditions. The laminates and modules were placed into experimental chambers at the end of day 0. ’No treatment’ refers to lake water without any additions. Results were means \(\pm\) SDs from duplicate experiments. use of laminates compared to modules (Figure 6a). The concentration of calcium in the control mesocosom was rather stable and fluctuated in a small range between 58 and 62 mg Ca\({}^{2+}\) L\({}^{-1}\) (Figure 6b). Similar values were observed in treated chambers (laminates and modules). The exception was a slightly higher concentration of 65 mg Ca\({}^{2+}\) L\({}^{-1}\) recorded after 3 weeks in the treatment with laminates (Figure 6b). In none of the mesocosms, the calcium concentration showed a trend in time. Alkalinity fluctuated in a small range of 3.1-3.3 mmol L\({}^{-1}\) (at the measurement accuracy of 0.2 mmol L\({}^{-1}\) (Figure 6c)). Although no trend could be seen, in the control mesocosom, the alkalinity was lower during the incubation, compared to the initial conditions; the same pattern could be noticed in the treatment using modules. Meanwhile, in the mesocosms with laminates, the alkalinity increased at some points in time compared to the initial level, especially at the end of the experiment (Figure 6c). Electrolytic conductivity changed in a small range between 400 and 420 \(\upmu\)S cm\({}^{-1}\). The dynamics in time were generally the same in all chambers, with a slight increase at the beginning of the experiment and further decline after 2 weeks (Figure 6d).