Anthropogenic activities in urban, agrarian, or industrial areas are the main cause of heavy metals in sediments worldwide. Since the 1960s, there have been submarine discharges through outfalls of poorly treated or untreated wastewater on the south coast of Mallorca island (Mediterranean Sea). In this study, the pollution of marine sediments is analyzed at a great number of points on the south of the seacoast. Heavy metal concentrations of As, Ba, Cd, Cr, Cu, Hg, Ni, Pb, Se, V, and Zn, total inorganic carbon (TIC), sulfur, mineralogy, and grain size were analyzed. The objective is to evaluate the concentrations of toxic substances and their spatial distribution and ranges that can negatively affect marine ecosystems and human health. In addition, the results obtained have been compared with standardized indices for marine sediments, and a regional index has been developed with the background values of heavy metals obtained in the sediments of the study area. To obtain consistent conclusions, concentrations of heavy metals were classified with the Igeo Index. The concentrations of heavy metals obtained show that a great number of samples exceeded the limits considered for uncontaminated sediments according to the index applied. Elements such as Hg, Ba, Pb, and Cu showed high concentrations close to the outfalls and lower concentrations in zones far from these points. To support the assessment, chemical processes such as dissolution or chemical precipitation have been studied. The results also show that marine sediments can be a good trap for chemical elements and a good proxy to analyze the impact of anthropogenic activities in areas heavily pressured by humans, and the risk to the environment and human health.

The alteration of marine sediments plays a key role in the global health of the seas as consequence of anthropogenic pollution in highly populated coastal areas. This research analyses the concentration and distribution of heavy metals in coastal and marine sediments of the Mediterranean Sea. Research has highlighted that Hg, Ni and Cu are present in very high concentrations in sediments, while Cr, Zn, Cd, Ba and V have slightly more moderate values. Sediment quality guidelines and the pollution indexes (Igeo and Geochemical Signal Type-GST) have been used to evaluate the trace element results, revealing a general trend of decreasing concentrations from the littoral coast to the open sea. Principal component analysis (PCA) indicates that the chemistry of metals in sediments is mainly regulated by the sequence Cu, Pb, Zn, Ba, and Cr. This study suggests that heavy metals distribution patterns are related to strong pressured tourist areas and management strategies are needed to ensure the health of the Mediterranean Sea.

Anthropogenic activities in the urban, agrarian, or industrial areas are the main cause of heavy metals in sediments worldwide. Since the 1960s there have been submarine discharges through outfalls of poorly treated or untreated wastewater on the south coast of Mallorca island (Mediterranean Sea). In this study, the pollution of marine sediments is analyzed at a great number of points on the south of the seacoast. Heavy metals concentrations of As, Ba, Cd, Cr, Cu, Hg, Ni, Pb, Se, V, Zn, Total Inorganic Carbon (TIC), Sulfur, mineralogy, and grain size were analyzed. The objective is to evaluate the concentrations of toxic substances and their spatial distribution and the ranges that can negatively affect marine ecosystems and human health. In addition, the results obtained have been compared with standardized indices for marine sediments and a regional index has been developed with the background values of heavy metals obtained in the sediments of the study area. To obtain consistent conclusions, concentrations of heavy metals were classified with the Igeo Index. The concentrations of heavy metals obtained show as a great number of samples exceeded the limits considered for uncontaminated sediments according to the index applied. Elements such as Hg, Ba, Pb, and Cu showed high concentrations close to the outfalls and lower concentrations in zones far from these points. To support the assessment chemical processes, such as dissolution or chemical precipitation have been studied. The results also show as marine sediments can be a good trap for chemical elements and a good proxy to analyze the impact of anthropogenic activities in areas heavily pressured by humans, and the risk to the environment and human health.