## 3 Results and Discussion
Anomalously elevated values (over 100 mg/L) were also found in the P2, P16, and P17A piezometers. In the monitored groundwater, apart from nickel and occasionally cadmium and lead, practically no significantly elevated concentrations of heavy metals were found. The vast majority of measurements of these metals (except nickel) indicated their very low concentrations (practically below the limits of their quantification). However, elevated nickel concentrations were still recorded (up to 0.69-0.75 mg/L in P18). In the monitored water, significantly increased iron content (up to 36-74 mg/L) was also found in P1. Additionally, iron content greater than 10 mg/L was found in the P18, P19, and P19A piezometers. Increased manganese content was found in practically all the piezometers except for P16 (0.016-0.028 mg/L) and P18 (0.051-0.041 mg/L), and the maximum concentrations reached 6.0-8.6 mg/L in P1 and 7.3 mg/L in P10. The results of physicochemical analyses from 2021 were taken into account in the overall water quality assessment based on the Regulation of the Minister of Maritime Economy and Inland Navigation of 11 October 2019, on the criteria and method of assessing the state of groundwater bodies. The results of the analyses made it possible to estimate that these are bodies of water of a poor chemical state (V class and in one case IV). Detailed information is provided in Table 3.  
The results of the chemical analysis for the chosen four years in all of the samples are illustrated in Table 4. Concentrations of Pb, Cd, Ni, Cu, Fe, and Zn are given in \(\mu\)g/L, and those of Cl, SO\({}_{4}\), and NH\({}_{4}\) in mg/L. The table presents the averaged data for the selected four years for which the values of the individual indices were calculated. The average values of the individual parameters were calculated on the basis of three (in 1995) or two values measured in the piezometers in particular years. \begin{table}
\begin{tabular}{c c c} \hline
**Piezometer** & **Class** & **Factors Determining Belonging to the Class** \\ \hline P1 & V & pH, EC, TOC, NH\({}_{4}\)\({}^{+}\), Fe, Mn, K, Cl\({}^{+}\) \\ P2 & V & pH, Mn \\ P9 & V & pH, NH\({}_{4}\)\({}^{+}\), K, Mn \\ P10 & V & EC, TOC, NH\({}_{4}\)\({}^{+}\), Na, K, Mn, B, Cl\({}^{-}\), HCO\({}_{3}\)\({}^{-}\) \\ P16 & IV & pH \\ P17 & V & EC, TOC, Na, Cl\({}^{-}\) \\ P17A & V & EC, TOC, NH\({}_{4}\)\({}^{+}\), Na, K, Mn, HCO\({}_{3}\)\({}^{-}\),Cl\({}^{-}\) \\ P18 & V & EC, TOC, NH\({}_{4}\)\({}^{+}\), Na, K, Fe, B, Ni, Cd, Cl\({}^{-}\), HCO\({}_{3}\) \\ P19 & V & TOC, NH\({}_{4}\)\({}^{+}\), K, Fe, Mn \\ P19A & V & EC, TOC, NH\({}_{4}\)\({}^{+}\), Na, K, Fe, B, HCO\({}_{3}\)\({}^{-}\) \\ \hline \end{tabular} Class IV is water of medium quality (the values of the water quality indicators increased as a result of natural processes and a weak anthropogenic impact), while Class V is water of poor quality (the values of the water quality indicators confirm an anthropogenic impact).  
\end{table} 
Table 3: Water quality classes determined on the basis of data from 2021. All indicator values presented in Figures 4-7 were calculated as sums of individual indicator values for individual parameters.