Assessment of metal contamination in coastal sediments of the Maluan Bay (China) using geochemical indices and multivariate statistical approaches

•Total metal concentrations and chemical forms in sediments were determined.•Geochemical indices and guidelines were used to assess quality of coastal sediments.•Two complex arrays of “hidden hotspots” of contaminants existed in Maluan Bay.•PCA/FA provided further evidence of the existence of clear pollution-risk gradients.•The integrative approach is a powerful tool to characterize the pollution status.

Total concentrations and chemical forms of heavy metals in surface sediments of Maluan Bay were determined and multiple geochemical indices and guidelines were applied to assess potential contamination and environmental risks. Metal concentrations exhibited significant spatial variation and the speciation of Cr was presented dominantly in the residual fraction, while Cd was found mostly in the non-residual fraction and thus of high potential bioavailability. Cluster analysis separated four subgroups of sampling sites with different levels of contamination. Further, a multivariate method offered the specific interpretation of possible contaminant sources and/or pathways. Factor scores characterized the sampling locations and elucidated the pollution status, pointing out the impact of multiple “hidden hotspots” of contaminants and providing further evidence of the existence of clear pollution-risk gradients in lagoon areas. The study supports the integrative approach as powerful tool to diagnose the pollution status scientifically for management decisions in coastal sediment of complex environment.

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