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Explora: Environment
and Resource Trace elements in Mediterranean mussels

mercury can be remobilized and become bioavailable to mines along approximately 300 km of the Mediterranean
organisms. Seasonal variations in mercury concentrations coast. Enormous quantities of lead and zinc sulfides
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in mussels were also observed and attributed to the in Cartagena (Sierra Almagrera), precious metals (gold
influence of water temperature, salinity, and primary and silver in Rodalquilar, Las Herrerías), and mercury-
productivity. 5,48 antimony (Valle del Azogue) have been extracted, and

Another very similar case is the site of the Gulf of some mines are still active. Despite this enormous volume
Augusta in Sicily (Italy), where the presence of a large of mining waste, no geochemical mapping of toxic element
industrial complex has caused significant anthropogenic anomalies has been carried out, and monitoring studies on
contamination in the soil, groundwater, and marine element distribution are generally limited to areas where
ecosystem. 43,50 Here, the Priolo petrochemical district, pollution has reached extremely high levels.
one of the largest in Europe, has been identified as a The most critical case is that of Portman Bay (Spain),
hotspot for mercury contamination. A chloro-alkali a heavily polluted area due to decades of mining waste
plant operating in the area released significant amounts disposal, which serves as a unique case study for
of mercury into the environment, leading to elevated understanding the potential impacts of deep-sea mining.
levels in sediments and marine organisms. Studies have The bay’s contaminated sediments, rich in elements
shown that mercury from the contaminated sediments is such as iron, zinc, arsenic, and lead, pose a significant
bioavailable to various marine species, including mussels environmental risk, particularly when resuspended. Mestre
M. galloprovincialis, at levels that exceed limits considered et al. conducted a transplant experiment using caged
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safe for human consumption. In addition, mercury levels mussels, M. galloprovincialis, during the summer of 2014.
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were elevated – up to approximately 5 µg/g (dry weight) Biomarkers and trace element accumulation were analyzed
– both in wild mussels and in a population translocated in mussel tissues, and the results were integrated with
within the investigated area, confirming the current sediment chemistry and toxicity bioassays. An increased
persistence of anthropic contamination and reinforcing, bioavailability for several elements was observed, although
once again, the utility of mussels as bioindicators. Long- these were differently distributed in the various tissues
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term monitoring studies in Augusta Bay, including the of analyzed mussels. Silver was found to be elevated, up
use of sentinel organisms such as fishes and mussels, have to approximately 2 µg/g (dry weight), in the gills, as was
revealed a decline in mercury levels in sediments and biota nickel, with values up to 0.6 µg/g (dry weight), antimony
following the closure of the chlor-alkali plant. However, with concentrations up to about 1 µg/g (dry weight), and
the persistence of mercury in the environment, coupled zinc showing levels exceeding 200 µg/g (dry weight). On
with its bioaccumulation potential, continues to pose a the contrary, lead values were elevated in digestive tissues,
threat to marine ecosystems and human health. 50 reaching a concentration of about 5 µg/g (dry weight).
On the other hand, the influence of natural enrichments, Overall, these results confirm widespread contamination
such as volcanic activity in the Gulf of Naples (Campania, of the study area, primarily linked to the resuspension of
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Italy) or the presence of minerals such as HgS in the sediments and fine particulate matter.
Mount Amiata area (Tuscany, Italy), adds to the baseline This pollution source is further influenced by the
contamination from industrial activities, urban runoff, and interaction of cyclonic and anticyclonic currents through
maritime traffic in the most densely populated areas. This the Strait of Gibraltar and north of Corsica. These
results in the phenomena of the increased bioavailability of currents converge in the Algerian marine basin and
mercury, which can be found in mussels at severe levels of meet in the Alboran Sea, where increased bioavailability
up to about 10 – 20 µg/g (dry weight) in organisms’ tissues and bioaccumulation phenomena have been observed
(Table 2). in marine species, including mussels. The Spanish
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Institute of Oceanography has conducted a long-term
3.3. Trace element pollution due to historical mining monitoring program using wild mussels to assess trace
activities in the southwestern Mediterranean element pollution along the Spanish Mediterranean
The Southwestern Mediterranean coast has a long history coast. Researchers observed significant variations in trace
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of polymetallic mineral mining, which has led to the severe element concentrations across different regions, with some
release of various trace elements into the environment areas showing elevated levels of arsenic, cadmium, copper,
over time. Spain, Morocco, Algeria, and Tunisia possess mercury, lead, and zinc due to anthropogenic activities,
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a variety of mineral deposits of volcanic origin, primarily mining, industrial discharges, and urban runoff. Table 3
oxides, sulfides, and other sulfur salts. Mining activity summarizes the historical range of bioaccumulation
along the southeastern coast of Spain has been exploited recorded in mussels from the Spanish Mediterranean
since ancient times and encompasses over 120 abandoned coast over 20 years (from 1993 to 2013), as proposed by

Volume 2 Issue 2 (2025) 10 doi: 10.36922/eer.8078