# Is It Possible to Restore a Heavily Polluted, Shallow, Urban Lake?
## 3 Results
### Mass Calculation  
The results of the research on the spatial variability of phosphorus content and its fractions in the Karczemne Lake sediments enabled the precise determination of sediment layers that need to be removed from particular sectors of the ecosystem bottom. The deposit thicknesses indicated for removal in each of the separated bottom sediment sectors are presented in Table 4. Considering the sector areas and the thickness of the layer to be removed, the volume of deposits to be dredged from Karczemne Lake was 240 013 m\({}^{3}\) (Table 4). Based on the density of the sediment and the degree of hydration, it was estimated that the fresh mass of the output will be 2,588,054.7 Mg and that the dry weight of the output will be 2691.35 Mg (Table 4). The amount of nutrients that will be removed from the ecosystem along with the sediments and interstitial waters will be 212.86 Mg of phosphorus and 405.67 Mg of nitrogen (Table 5).  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Parameter** & **Norm** & **SampleNo. 1** & **SampleNo. 2** & **SampleNo. 3** & **SampleNo. 4** & **SampleNo. 5** \\ \hline As & \textless{}30 mg/kg d.w. & 9.77 & 5.0 & 13.3 & 6.05 & 12.7 \\ \hline Cr & \textless{}200 mg/kg d.w. & 29.1 & 18.8 & 40.1 & 33.2 & **44.1** \\ \hline Zn & \textless{}1000 mg/kg d.w. & 406.0 & 104.0 & 503.0 & 152.0 & 843.0 \\ \hline Cd & \textless{}7.5 mg/kg d.w. & 0.543 & 0.050 & 0.794 & 0.050 & 0.846 \\ \hline Cu & \textless{}150 mg/kg d.w. & 93.5 & 25.9 & 123.0 & 38.4 & 247.0 \\ \hline Ni & \textless{}75 mg/kg d.w. & 19.9 & 13.8 & 25.8 & 21.9 & 22.5 \\ \hline Pb & \textless{}200 mg/kg d.w. & 97.2 & 31.6 & 126.0 & 49.4 & 317.0 \\ \hline Hg & \textless{}1.0 mg/kg d.w. & 0.60 & 0.22 & 0.68 & 0.26 & 0.30 \\ \hline Benzo(a) anthracene & \textless{}1.5 mg/kg d.w. & 1.13 & 0.361 & 1.69 & 0.240 & 13.0 \\ \hline Benzo(b) fluoranthene & \textless{}1.5 mg/kg d.w. & 1.88 & 0.69 & 3.57 & 0.55 & 14.40 \\ \hline Benzo(k) fluoranthene & \textless{}1.5 mg/kg d.w. & 0.803 & 0.270 & 1.380 & 0.246 & 5.770 \\ \hline Benzo(g, h, i) perylene & \textless{}1.0 mg/kg d.w. & 1.44 & 0.548 & 2.65 & 0.72 & 7.34 \\ \hline Benzo(a) pyrene & \textless{}1.0 mg/kg d.w. & 1,21 & 0.410 & 2.10 & 0.39 & 9.75 \\ \hline Dibenzo(a, h) anthracene & \textless{}1.0 mg/kg d.w. & 0.297 & 0.020 & 0.482 & 0.020 & 3.24 \\ \hline Indeno(1, 2, 3-cd) pyrene & \textless{}1.0 mg/kg d.w. & 1.75 & 0.976 & 1.86 & 0.916 & 8.03 \\ \hline \end{tabular}
\end{table}
Table 3: Organic pollutants and heavy metal contents in bottom sediment of Karczemne Lake.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Number of Sampling Point**} & **Sector Area** & \begin{tabular}{c} **The Thickness of** \\ **Layer to Be Removed** \\ **(m)** \\ \end{tabular} & \begin{tabular}{c} **Volume of the Layer** \\ **to Be Removed** \\ **(m\({}^{3}\))** \\ \end{tabular} & \
\begin{tabular}{c} **Wet Sludge Mass to** \\ **Be Removed** \\ **(kg m\({}^{-2}\))** \\ \end{tabular} &
\begin{tabular}{c} **Dy Sludge Mass to** \\ **Be Removed** \\ **(kg m\({}^{-2}\))** \\ \end{tabular} \\ \hline  
& 8,529,586.9 & 615,247.2 \\ Total & **360,823** & **-** & **240,013** & **2588,054.7 Mg** & **269,173.5 Mg** \\ \hline \hline \end{tabular}
\end{table}
Table 4: Characteristics of physical parameters of bottom sediments with respect to the spatial volume balance and the mass of potential output to be removed.  
\begin{table}
\begin{tabular}{c} **The Content of TN** \\ **in Interstitial Water** \\ \end{tabular} \\ \hline
1 & 10,273 & 0.46 & 4691.2 & 0.94 & 9697.7 & 1.62 & 16.66 & 10.60 & 109.28 \\
2 & 15,100 & 0.49 & 7468.5 & 1.12 & 16,966.2 & 1.45 & 21.86 & 7.68 & 116.02 \\
3 & 6000 & 0.6 & 3769.7 & 1.47 & 8830.2 & 0.68 & 4.06 & 5.11 & 30.67 \\
4 &