Fig. 7From: Metal contamination in a sediment core from Osaka Bay during the last 400 yearsHeatmap of correlation coefficients based on the symmetric coordinates for the bulk sediment. Blue colors indicate negative and brown and red colors indicate positive correlations. The elements were sorted based on the cluster analysis as suggested by Reimann et al. (2017). The cluster of Cu, Zn, and Pb in the lower left indicates that these elements could share the same originBack to article page