Simulated annealing and kriging method for identifying the spatial patterns and variability of soil heavy metal

Environmental data, including information regarding soil heavy metals, may contain significant uncertainty and exhibit a skewed distribution with a complex and unexplainable spatial variation. This study identified the spatial patterns and variations of soil heavy metals (Cu, Cd, Hg, and Pb) in the northern part of Changhua County in Taiwan to clarify the characteristics and pollution of soil heavy metals. The spatial maps of soil heavy metals were also estimated and simulated using kriging and simulated annealing methods. Correlation analysis indicated that Pearson and Spearman correlation coefficients among these four heavy metals were significant; between Cd and Cu, these two correlation coefficients were strongly significant. As expected, the spatial maps of estimation and simulation of soil heavy metals revealed high concentration areas of Cd, Cu along the main irrigation‐ditch system and surrounding industrial plants in the area of study. In addition to reproducing the spatial variation of the investigated Cd, Cu, Hg and Pb, simulated annealing could also identify the global spatial continuity and discontinuity patterns of soil heavy metals. Kriging and simulated annealing methods can both be applied to identify pollution sources and patterns for monitoring and remedy.