Effects of bio-chemo-mechanical processes on the properties of contaminated marine sediments

A detailed multi-scale investigation of the geotechnical, chemical and mineralogical properties was conducted on contaminated sediment samples collected within the Mar Piccolo, a marine basin in south of Italy. The basin is located close to one of the most important industrial sites in Europe also declared ‘at high risk of environmental crisis’ and prioritised for remediation activities. A multidisciplinary investigation campaign showed that the samples collected close to the seafloor are characterized by high values of both heavy metals and organic pollutants and by the presence of significant amount of organic matter. Several samples in the top layer exhibited peculiar geotechnical properties, in terms of plasticity and activity indexes, compressibility and hydraulic permeability. While the prime suspect for such unconventional behaviour was the chemo-mechanical coupling between soil skeleton and contaminants, it turned out that the biogeochemical degradation of organic matter and the presence of microfossils and diatoms is likely to affect significantly the micro to macro behaviour of polluted marine sediments.

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Marine Sediments from a Contaminated Site: Geotechnical Properties and Chemo-Mechanical Coupling Processes

Geosciences ◽

10.3390/geosciences9080333 ◽

2019 ◽

Vol 9 (8) ◽

pp. 333 ◽

Cited By ~ 3

Author(s):

Francesca Sollecito ◽

Claudia Vitone ◽

Daniela Miccoli ◽

Michael Plötze ◽

Alexander M. Puzrin ◽

...

Keyword(s):

Urban Areas ◽

Data Interpretation ◽

Environmental Crisis ◽

Contaminated Site ◽

Standard Equipment ◽

Mechanical Coupling ◽

Industrial Sites ◽

The Rich ◽

High Concentrations ◽

Coupling Processes

The city of Taranto in the south of Italy is one of the areas declared as “at high risk of environmental crisis” by the Italian government because it represents one of the most complex industrial sites in Europe, located near urban areas of high population density. The rich ecosystem of the Mar Piccolo basin, located at north of Taranto, started exhibiting unconfutable signs of environmental pollution, confirmed by the high concentrations of organic and inorganic contaminants. Among the different aspects involved in the environmental studies aiming at the basin remediation, this paper focuses on submarine sediments and reports some results of the geotechnical laboratory investigations which made also use of non-standard equipment and revised procedures for data interpretation in order to take account of the sediments’ contamination and heterogeneities. The geotechnical laboratory tests show that, despite the Mar Piccolo recent Holocene sediments having similar origin and composition to those of the Sub-Apennine clay basic formation, their behavioral facets appear to be altered by the presence of contaminants of both natural and anthropogenic origin. Results of washing tests are also presented as a first attempt to quantify the effects of chemo-mechanical coupling processes on the plasticity properties of the shallow sediments.

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