Uptake, localization and effects induced by emerging pollutants in plants: evaluation by cryptogams and phanerogams

My PhD work was divided into two phases, according to the aims of my research project: 1) Identify moss species that are good biomonitors of emerging airborne pollutants, especially PAHs, and study the way of interception of these pollutants by moss tissues. 2) Study the effects of heavy metals in selected higher plants evaluating biomass production and tolerance to HM stress, and to estimate their phyto-extracting or phyto-stabilizing capacities for certain heavy metals. As for the biomonitoring of air quality, a Sphagnum palustre clone and three native mosses such as Hypnum cupressiforme, Plagiomnium affine and Amblystegium humile were tested. I focused my attention on the interception and accumulation modes by polycyclic aromatic hydrocarbons (PAHs) by selecting the phenanthrene as target molecule. These pollutants are more difficult to trace than metals because they can be degraded and can be found in the environment in gaseous form or in particles depending on their weight and air temperature; The phenanthrene is self-fluorescent and emits in the red light (620-750 nm), the same wavelength of chlorophyll. Previous work indicated that phenanthrene accumulates in vacuoles, but being the PAHs lipophilic molecules, their accumulation in aqueous compartments such as vacuole seemed unlikely. The results showed that phenanthrene, even opportunely dissolved, aggregates in particles, intercepted by moss surface. The results highlight that among the tested moss species S. palustre was the most efficient in phenanthrene uptake, likely due to its surface properties. In Sphagnum palustre it is accumulated on leaf surface and in hyalocysts, dead empty cells acting in water storage. but Phenanthrene uptake is different depending on moss species. Anyway Physical-chemical characterization of moss surface is the forthcoming step to understand the basis of phenanthrene uptake. As for the point 2 I tested the use of vascular plants with high production of biomass and/or high capacity of bioaccumulation of HM to evaluate their application in phytoremediation or phytostabilization actions; the selected species were Cynara cardunculus e Zea mays. The results showed for both species a good capacity to accumulate Cd and Pb, the first both in shoot and in root and the second mostly in root tissue. Neverthless, C. cardunculus was more sensitive to Pb than Cd while an opposite result was observed in Z. mays, suggesting that both species could be suitable candidate for phytoremediation action (especially phytostabilization), thaking into account their different response depending on the different pollutant. In addition to the effect of toxic metals, the influence of a nutrient (Mn) on mineral uptake was tested as well. In particular, I tested the response of Cistus salvifolius, a species native of a soil very rich in heavy metals, to growing concentration of Manganese. The experiment, carried out in hydroponic culture, showed both an increase of its uptake depending on applied concentrations, and an influence of the Mn on the uptake of some important nutrients such as Mg, K, Fe, Zn; this indicatse that Mn can affect mineral nutrition in C. salvifolius