Heavy metals in group Ib (Fig. 2b) are represented as negative
scores in PC1 and positive scores in PC3 (supplementary material
Table S3). Group II (a) in Fig. 2b represents the close relation of
Hg, Cr and Cd which are represented as high positive scores in PC1
respectively. The high median concentration in IS and NFecas and
low median concentrations in PbM, CuM and NFe made Hg, Cr and
Cd to fall under one group (Fig. 2b). The metals Cr and Cd both
are known for its corrosion resistance properties and commonly
used in electroplating of steel [47]. Se and Sb (Fig. 2b) showed similar
trends in different processes waste, which may be due to their
common applications as pigment in metallurgy and glass making
[30,34].