Potentially toxic element availability and risk assessment of cadmium dietary exposure after repeated croppings of brassica juncea in a contaminated agricultural soil

Phytoextraction of potentially toxic elements (PTEs) is eco-friendly and cost-effective for remediating agricultural contaminated soils, but plants can only take up bioavailable forms of PTEs, thus meaning that bioavailability is the key for the feasibility of this technique. With the aims to assess the phytoextraction efficiency on an agricultural soil contaminated by Cr, Zn, Cd, and Pb and the changes induced by plants in PTE bioavailability and in human health risk due to dietary exposure, in this work we carried out a mesocosm experiment with three successive croppings of Brassica juncea, each followed by Rocket salad as bioindicator. Brassica juncea extracted more Zn and Cd than Cr and Pb, significantly reducing, after three repeated croppings, the bioavailable element concentrations in soil as a result of plant uptake and soil pH changes. For Cd, this reduction did not bring the bioavailable amounts obtained by soil extraction with NH4NO3 below the trigger value of 0.1 mg kg−1 set by some European countries. Nevertheless, the Hazard Quotient for Cd in Rocket salad decreased across three repeated croppings of Brassica juncea. This indicated the beginning of a re-equilibration process between soil PTE forms of different bioavailability, that are in a dynamic equilibrium, thus stressing the need to monitor the possible regeneration of the most readily bioavailable pool

Degradative actions of microbial xylanolytic activities on hemicelluloses from rhizome of Arundo donax.

Polysaccharidases from extremophiles are remarkable for specific action, resistance to different reaction conditions and other biotechnologically interesting features. In this article the action of crude extracts of thermophilic microorganisms (Thermotoga neapolitana, Geobacillus thermantarcticus and Thermoanaerobacterium thermostercoris) is studied using as substrate hemicellulose from one of the most interesting biomass crops, the giant reed (Arundo donax L.). This biomass can be cultivated without competition and a huge amount of rhizomes remains in the soil at the end of cropping cycle (10–15 years) representing a further source of useful molecules. Optimization of the procedure for preparation of the hemicellulose fraction from rhizomes of Arundo donax, is studied. Polysaccharidases from crude extracts of thermophilic microorganisms revealed to be suitable for total degradative action and/or production of small useful oligosaccharides from hemicelluloses from A. donax. Xylobiose and interesting tetra- and pentasaccharide are obtained by enzymatic action in different conditions. Convenient amount of raw material was processed per mg of crude enzymes. Raw hemicelluloses and pretreated material show antioxidant activity unlike isolated tetra- and pentasaccharide. The body of results suggest that rhizomes represent a useful raw material for the production of valuable industrial products, thus allowing to increase the economic efficiency of A. donax cultivation

From theory to the complex geospatial ground-truth of contaminated soils.

Characterization and subsequent reclamation of contaminated sites require detailed knowledge of the geospatial distribution of contamination. In Italy, a potentially contaminated site is an area where the concentration of one or more contaminants in soils is above land-use legal limits (CSC according to Italian law 152/06). Four main phases have to be followed to assess contamination and then reclamation: 1) preliminary conceptual model, 2) characterization plan, 3) site specific risk analysis (by Risk-net software) setting the contamination threshold concentration (CSR), 4) assessment of contamination and therefore reclamation action by comparison between CSC and CSR. The geospatial distribution of contaminants is considered in the characterization plan. It is mandatory to sample at least three samples for each surveyed point (one sample in the 0 to 1 m depth, one sample in the capillary fringe zone and one in between). There aren’t clear indications on the sampling strategy and spatial density. According to Italian law (D.M. 471/99), it is usual to identify 5 to 15 sampling points for areas of 1 to 5 hectares. In this work we attempt to answer the question: “After more than a decade from the introduction of law 152/06 and considering the progress of scientific knowledge, are these soil sampling criteria suitable for assessing the spatial and volumetric distribution of site contamination? We considered the analytical and spatial dataset obtained from two rural and industrial potentially polluted sites of south Italy, formerly interested by past disposal of industrial sludge and wastes. In both sites results showed that: (i) the geospatial variability of contamination is always much more complex than expected and depends by the history of the contamination; (ii) the sampling of the first meter - as a single body - is not satisfactory because it does not take into account the real vertical distribution of pollutants and the soil stratigraphy (such as the presence of centimeter horizons). The work illustrates the use of proximal sensing sensors, such as EMI, ARP, portable gamma-ray spectrometers and portable XRFs to obtain detailed mappings for homogeneous areas identification, where to address subsequent pedological and chemical investigations. Moreover, the pedological observation - guided by these technologies - often provides essential information to understand the process of emplacement and possible migration of pollutants towards other environmental sectors. The applied integrated approach, which was found very relevant for the site characterization, can assume even greater importance in the subsequent phase of reclamation

Molecular Interactions and Properties of Biologically Active Compounds: Infrared and Raman Spectroscopic Studies

The correlation between molecular interactions and properties of biomolecules is a pre-eminent problem in the biological field. H-bond interactions in different classes of biomolecules, such as phospholipids, polypeptides, polynucleotides, polyamines and neurotransmitter-receptors, are here discussed by vibrational infrared and Raman spectroscopy. Effects of the strength, non-stoichiometry, and of the water molecules on this type of bond have been considered and correlated with structural and biological modifications

Ozone and water stress: effects on the behaviour of two white clover (Trifolium repens L.) biotypes.

Since ozone penetration in vegetation occurs mainly through stomata, all factors which alter plant-atmosphere relations could be able to modify plant response to ozone. Interaction between ozone and water stress in Mediterranean environment was studied on ozone resistant (R) and sensitive (S) biotypes of white clover, which were grown in charcoal filtered and not-filtered Open Top Chambers. Measurements of biomass, leaf area and stomata conductance were made during the growth period. Ozone injuries were estimated by the ratio between biomass yield gained in not-filtered and in filtered OTC; ozone uptake was estimated by the stomata conductance and ozone hourly concentrations. In presence of ozone, biomass yield was higher in R biotype than in S biotype, while no difference between the two biotypes was recorded in filtered air. Water stress partially reduced ozone injuries, as well as water stress effect was partially reduced in S biotype grown in the presence of ozone, while no interaction between ozone and water stress was noticed in R biotype. Yield losses of S was significantly correlated to cumulated ozone uptake, while yield losses of R was not influenced by variations in ozone fluxes. Flux based models could better estimate yield losses due to ozone in Mediterranean environments in which other stresses could be contemporary present; therefore, the new European directives might modify the actual thresholds based on ozone concentration with others based on models of stomata flux of ozone