Process of soil pollution and remediation
Contact: Meri Barbafieri (Unit of Pisa)
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Environmental pollution is a major threat to our planet. Pollution of precious water supplies is particularly important. Electric utilities, oil refineries, and chemical plants produce huge amounts of contaminated wastewater each year. In agriculture, toxic levels of various elements pollute the groundwater as a result of excessive fertilizer application (e.g., nitrates and phosphates), and through leaching of naturally occurring trace elements in the soil after irrigation (e.g., selenium). Pollution of both water and soil poses a significant hazard to human health.
Finding suitable treatment technologies to clean up contaminated water and soil is not easy. Many technologies that are available are usually very expensive. Because the need for practical and cost-effective procedures for cleaning up contaminated water and soil is so great, researchers in this group have dedicated themselves to achieving this goal through the study of process involved in soil pollution and analyze the best solution to apply. Among many technologies considered, Phytoremediation appears as a cost-effective and environment-friendly approach for cleanup.
Many agricultural and industrial sites have soils that are contaminated with toxic heavy metals, metalloids (e.g., boron, arsenic), or organic pollutants (e.g., PAH’s) These sites may be remediated or restored using different Phytoremediation approaches. Phytoextraction utilizes the ability of certain plants to remove contaminants from soil and water and accumulate them in plant tissues that may then be harvested and removed from the site. Phytostabilization on the other hand, uses plants to immobilize contaminants chemically and physically at the site, thereby preventing their movement to ground waters or to the atmosphere (i.e., through soil erosion and wind). Phytovolatilization makes use of plants and their associated microbes to convert contaminants to a volatile form and remove them from the local ecosystem. Phytodetoxification involves the ability of plants to change the chemical species of the contaminant to a less toxic form, e.g., plants can take up toxic hexavalent chromium and convert it to non-toxic trivalent chromium.
Research:
Essential contribution is devoted to the right selection of strategies to recover contaminated soil. The choice is based of knowledge of basic principles of soil characteristics and analysis of pollutants speciation and bioavailability.
Among the different remediation technologies the main activities are focused on Phytoremediation under public and private funded contracts. Consolidate knowledge and experience have been gained in the last 15 years and are related to:
- Basic research: to study and implement the technology. Investigations under multidisciplinary approach are conducted in the evaluation of different plant species on contaminant accumulation and distribution evaluating the strategic factors of phytoremediation processes. Phytotoxicity is studied evaluating Biomarkers of oxidative stress and metal induced protein in cooperation with CNR-IBF (Dr. E. Morelli) and genotoxicity in cooperation with CNR-IBBA (Dr. L. Giorgetti).
- Site specific applicability test: feasibility tests are necessary to develop before any technology application. Phytoremediation also is subjected to this demand. The studies are carried out at different experimental scale (see the scheme in figure below). Field test are particularly important in the technology evaluation and experimentation.
Other related studies/activities are focused on:
- metal bioavailability and phytoextraction technology
- study of behavior and transport/translocation of nanoparticles in the soil/plant system (cooperation with Prof. George Gardea Torresday, Texas University, Chemistry Department: Cerium nanoparticles tolerance and toxicity in Helianthus annus)
- in-situ characterization of metal polluted soil by means LIBS
