Figure 2
The figure consists of four vertical bar graphs. The horizontal axis in all graphs is labeled with the elements “Cadmium”, “Chromium”, “Nickel”, and “Lead”, arranged from left to right. The vertical axes differ across graphs and include error bars on each bar indicating variability. The first graph in the top left is labeled “a)”. The horizontal axis consists of four vertical bars arranged from left to right. The vertical axis ranges from negative 0,6 to 0,8 in increments of 0,2 units. A horizontal reference line is drawn at 0. The data for the bars are as follows: Cadmium: negative 0,39 with an error bar ranging from about negative 0,41 to negative 0,37. Chromium: 0,1 with an error bar ranging from about 0,08 to 0,12. Nickel: 0,42 with an error bar ranging from about 0,40 to 0,44. Lead: 0,58 with an error bar ranging from about 0,55 to 0,61. The second graph in the top right is labeled “b)”. The horizontal axis consists of four vertical bars arranged from left to right. The vertical axis ranges from 0,0 to 2,5 in increments of 0,5 units. A horizontal reference line is drawn at 2,0. The data for the bars are as follows: Cadmium: 1,1 with an error bar ranging from about 1,0 to 1,2. Chromium: 1,55 with an error bar ranging from about 1,45 to 1,65. Nickel: 1,95 with an error bar ranging from about 1,85 to 2,05. Lead: 2,15 with an error bar ranging from about 2,0 to 2,3. The third graph in the bottom left is labeled “c)”. The horizontal axis consists of four vertical bars arranged from left to right. The vertical axis ranges approximately from 0,0 to 2,5 in increments of 0,5 units. A horizontal reference line is drawn at 1,0. The data for the bars are as follows: Cadmium: 1,15 with an error bar ranging from about 1,05 to 1,25. Chromium: 1,6 with an error bar ranging from about 1,5 to 1,7. Nickel: 2,05 with an error bar ranging from about 1,95 to 2,15. Lead: 2,2 with an error bar ranging from about 2,1 to 2,3. The fourth graph in the bottom right is labeled “d)”. The horizontal axis consists of four vertical bars arranged from left to right. The vertical axis ranges approximately from 0,0 to 3,0 in increments of 0,5 units. A horizontal reference line is drawn at 1,0. The data for the bars are as follows: Cadmium: 2,25 with an error bar ranging from about 2,15 to 2,35. Chromium: 2,75 with an error bar ranging from about 2,6 to 2,9. Nickel: 1,3 with an error bar ranging from about 1,2 to 1,4. Lead: 0,95 with an error bar ranging from about 0,85 to 0,98. Note: All numerical data values are approximated.Own elaboration graph comparing single-metric contamination indices for Cd, Cr, Ni and Pb: (a) Geoaccumulation index (Igeo), (b) Enrichment Factor (EF; Al reference), (c) Contamination Factor (CF), (d) Pollution Index (PI; preventive limits as reference). Class thresholds follow Weissmannová and Pavlovský (2017). Error bars represent ± standard deviation of analytical triplicates