## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & **Year** & **Pb** & **Cd** & **Ni** & **Cu** & **Fe** & **Zn** & **Cl** & **SO4** & **NH4** \\  & **Hg/L** & **Hg/L** & **Hg/L** & **Hg/L** & **Hg/L** & **Hg/L** & **Hg/L** & **Hg/L** & **Hg/L** & **Hg/L** \\ \hline \multirow{4}{*}{P1} & 1995 & 40.0 & 4.0 & 50.0 & 10.0 & 4460.0 & 60.0 & 124.0 & 133.7 & 0.2 \\  & 2003 & 20.0 & 5.0 & 130.0 & 15.0 & 5860.0 & 90.0 & 376.0 & 195.0 & 1.4 \\  & 2010 & 10.0 & 1.0 & 4.0 & 4.0 & 34,450.0 & 5.0 & 260.0 & 220.0 & 27.5 \\  & 2021 & 4.0 & 5.0 & 48.0 & 4.0 & 55,000.0 & 32.0 & 772.0 & 179.0 & 56 \\ \hline \multirow{4}{*}{P2} & 1995 & 410.0 & 5.0 & 37.0 & 18.0 & 2.0 & 87.0 & 106.3 & 165.7 & 0.0 \\  & 2003 & 20.0 & 5.0 & 27.0 & 20.0 & 64.0 & 13.0 & 95.5 & 129.4 & 0.0 \\  & 2010 & 10.0 & 1.0 & 4.0 & 6.0 & 177.0 & 5.0 & 125.4 & 165.0 & 13.8 \\  & 2021 & 4.0 & 5.0 & 17.0 & 7.0 & 250.0 & 45.0 & 42.0 & 115.0 & 1.8 \\ \hline \multirow{4}{*}{P8} & 1995 & 20.0 & 5.0 & 10.0 & 7.0 & 31,100.0 & 60.0 & 41.2 & 128.0 & 1.3 \\  & 2003 & 20.0 & 5.0 & 10.0 & 20.0 & 22,010.0 & 10.0 & 35.5 & 116.4 & 0.1 \\  & 2010 & 10.0 & 1.0 & 4.0 & 4.0 & 13,300.0 & 39.0 & 87.2 & 120.0 & 0.4 \\  & 2021 & - & - & - & - & - & - & - & - & - \\ \hline \multirow{4}{*}{P9} & 1995 & 20.0 & 5.0 & 40.0 & 10.0 & 54.0 & 65.0 & 88.0 & 92.3 & 0.3 \\  & 2003 & 20.0 & 5.0 & 15.0 & 18.0 & 243.0 & 12.0 & 129.7 & 87.0 & 0.1 \\  & 2010 & 10.0 & 1.0 & 5.0 & 5.0 & 170.0 & 36.0 & 65.6 & 130.0 & 18.9 \\  & 2021 & 4.0 & 5.0 & 48.0 & 7.0 & 7850.0 & 37.0 & 195.0 & 84.0 & 20.0 \\ \hline \multirow{4}{*}{P10} & 1995 & 60.0 & 39.0 & 65.0 & 10.0 & 1070.0 & 89.0 & 769.7 & 271.3 & 41.4 \\  & 2003 & 20.0 & 5.0 & 68.0 & 30.0 & 22,600.0 & 13.0 & 783.8 & 143.8 & 282.9 \\  & 2010 & 10.0 & 1.0 & 4.0 & 4.0 & 860.0 & 8.0 & 341.0 & 65.0 & 79.6 \\  & 2021 & 4.0 & 5.0 & 41.0 & 4.0 & 8160.0 & 42.0 & 571.0 & 85.0 & 115.5 \\ \hline \multirow{4}{*}{P16} & 1995 & - & - & - & - & - & - & - & - & - \\  & 2003 & 20.0 & 3.0 & 24.0 & 18.0 & 81.0 & 15.0 & 24.3 & 94.9 & 0.3 \\  & 2010 & 10.0 & 1.0 & 4.0 & 4.0 & 30.0 & 15.0 & 22.6 & 80.0 & 0.4 \\  & 2021 & 4.0 & 5.0 & 18.0 & 4.0 & 150.0 & 32.0 & 33.0 &The values obtained for the HR index varied over the years. In 1995, it was not possible to calculate this index due to the absence of the P16 piezometer. The values of the index calculated for the year 2003 would indicate that the water in all the piezometers was more polluted at the beginning of the system than after flowing under the landfill. This would suggest that the landfill had no impact on the water quality in the analyzed area, which is an incorrect conclusion when considering the groundwater monitoring results (Figure 4). The total (very high) value of the index was due to the identical (low) values of heavy metals in the water both in the P16 piezometer and in other piezometers belonging to the observation network, as well as in the increased concentration of chromium, which was as much as 12 times higher than the values measured in other piezometers. However, the values of this index for 2010 indicate the impact of the landfill on groundwater. In one case (P19 piezometer), the value of the index was higher than 10, which is related to the low content of sulphates in the water of this piezometer. The values obtained for the HR index indicate the negative impact of the landfill. However, as in the previous period, they were affected by the very low concentration of sulphates in the water of the P18 piezometer and the P19 piezometer. As a result, for this single component alone, the total index value increased to over 16, while the value of 15 was for the sulphates alone (Appendix A). So far, this indicator has not been used for groundwater in Poland. In the case of studies conducted in the area of other landfills [17], higher values of the HR index were obtained. Values for a single component reached 2.5. This value was calculated for copper. The total value of the indicator obtained by the authors of the article on the landfill in Nigeria was about 10.