A device to study the effect of space radiation on photosynthetic organisms

This research concerns the study of the effects of ionising space radiation on the oxygen-evolving activity of algae and cyanobacteria, focusing our attention on Photosystem II (PS-II), the oxygen-evolving complex. These microorganisms as higher plants, can use light energy to split water molecules and evolve oxygen in a process that produce storable energy-rich products from atmospheric carbon dioxide. Algae and cyanobacteria which can grow in the presence of nutrients and carbonate are expected to be utilised to maintain an oxygen-atmosphere and to constitute biomass in space shuttles. Irradiation was performed in gamma 60Co-sources of different activities; fluorescence techniques in vivo and SDS-PAGE analysis in vitro were used to determine PS-II efficiency during radiation stress. We determined the radiation target on PS-II by immunoblot. We built a miniaturised growth box that preserves constant pressure and temperature to measure automatically photosynthetic activity by a fluorescence sensor, directly in space during a mission in an ASI balloon.

A bio-dosemeter that utilises isolated enzymes to detect ionising radiation

The development of a biosensor for the detection of ionising radiation (biodosemeter) utilising the advantageous properties of the photosystem II (PSII) complex and its response to ionising radiation is reported. The transducer signal for this biosensor can be fluorescence, which is dependent on photosynthetic activity. Exposure of biological material to ionising radiation leads to a loss of function due to the destruction of critical structures. Radiation target theory predicts an exponential decrease in biochemical activity that is dependent on the absorbed radiation energy and directly proportional to the mass of the individual molecules possessing this activity. The activity is lost whenever the protein is hit since very high energy is transferred through the chain. Several approaches were used to optimise the immobilisation of PSII complexes to improve the sensitivity of the bio-dosemeter.

Environmental assessment of a site contaminated by organic compounds

This paper presents a study on environmental assessment of an abandoned industrial area located in central Italy. Main production was refractory materials and compounds for treatment of industrial wastewater. The present work deals with a methodology for development of a sound sampling design, chemical characterization of soil samples, definition of the degree of site contamination according to law limits and evaluation of the fate and transport of contaminants by EPA simulation model (VLEACH 2.2a). Results indicate that toxic compounds (polycyclic aromatic hydrocarbons and plasticizers) are uniformly distributed in the contaminated site and only in one sampling point their concentrations exceed law limits. Modeling results confirm that contaminants migration to groundwater can be excluded, addressing for a site remediation limited to the surface layer.