Natural and anthropogenic heavy metals in estuarine cohesive sediments: geochemistry and bioavailability.

GRECCO L. E.; GÓMEZ E.A.; BOTTÉ S.; MARCOS A.O.; MARCOVECHIO J.; CUADRADO, DIANA G.

OCEAN DYNAMICS

SPRINGER HEIDELBERG

Lugar: HEIDELBERG; Año: 2010 vol. 61 p. 285 - 293

1616-7341

The geochemistry, mineralogy, and grain sizedistribution of several estuarine cohesive sediment samplesfrom potentially human-influenced areas without suchan influence were analyzed to determine the natural heavymetal content and evaluate its impact on the Bahía Blancaestuarine environment. The data were compared withdifferent ranges of concentrations for heavy metals inmarine sediments established by the NOAA ScreeningQuick Reference Tables in which values range frombackground levels to those considered toxic to the marineenvironment. Our total heavy metal contents were belowthe established hazardous levels in all the analyzedsamples, even though the potentially human-influencedareas (harbors, industry, urban spread) showed the highesttotal concentration values as well as greater percentages ofbioavailable compounds. This would imply a low and notextensive anthropogenic input into the environment. Therelatively high proportions in which Cd, Pb, and Cr appearas bioavailable compounds at some sites not influenced byhuman activity suggest the presence of a natural source forthese elements. This could be attributed to the weatheringof naturally occurring volcanic minerals, indicating thatspecial care must be taken when monitoring of sedimentfor anthropogenic activity is carried out within thisenvironment. According to the results obtained, and inorder to minimize the environmental impact caused byperiodic water injection dredging, relocation of sewageoutfalls from vessel mooring areas into open waters isstrongly recommended.