Fig. 5.

Relationship between effect size of 8 heavy metals and the soil pH, mean annual precipitation (MAP), mean annual temperature (MAT), and farmland use patterns based on data during 2010–2021 and the background values in 1990. Values of effect sizes are calculated at the 95% CIs. A ratio of 0 (or CI = 0) means statistically no significant difference between the 12-year data and the background levels. A ratio greater than 0 indicates an increase of a pollutant compared with the background levels, whereas a ratio less than 0 indicates a decrease.