Fig. 1
![Fig. 1](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs12302-020-00446-y/MediaObjects/12302_2020_446_Fig1_HTML.png)
Number of public sites with residue contamination for each season. Percentage of contaminated sites for each season in parenthesis (N = 24 sites per season). p-values denote differences in relation to the winter season as reference (Fishers-exact test with Bonferroni correction)