Sorrentino, Maria Cristina (2021) Response and tolerance to pollutants by plants: perspectives in biomonitoring and phytoremediation. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Resource language: English
Title: Response and tolerance to pollutants by plants: perspectives in biomonitoring and phytoremediation
Sorrentino, Maria
Date: 1 July 2021
Number of Pages: 157
Institution: Università degli Studi di Napoli Federico II
Department: Biologia
Dottorato: Biologia
Ciclo di dottorato: 33
Coordinatore del Corso di dottorato:
Spagnuolo, ValeriaUNSPECIFIED
Date: 1 July 2021
Number of Pages: 157
Keywords: Metal pollution; environmental quality; PAHs
Settori scientifico-disciplinari del MIUR: Area 05 - Scienze biologiche > BIO/01 - Botanica generale
Date Deposited: 23 Jul 2021 10:46
Last Modified: 07 Jun 2023 10:39

Collection description

Environmental pollution represents one of the modern challenges for scientific community; researchers should indeed, increase resources to improve green and low-cost technologies for monitoring compromised ecosystems, and developing new eco-friendly methodologies for their recovery. Plant organs and associated microbiota interact with pollutants in the phyllosphere and rhizosphere to remediate (or mitigate the effects) of contaminants not only in soils but also in the air. This makes phytoremediation one of the possible green technique in the control of air pollution. Phytoremediation is indeed not only considered as a method to return soils to agriculture for food and feed production, but also as a technique to control air pollution by avoiding the resuspension of contaminated PM (Particulate Matter). This consideration makes it clear that phytoremediation and air biomonitoring represent two interconnected aspects in the framework of plant-abiotic stress interaction. These two related aspects represent the research area of my Ph.D. project. As for soil phytoremediation I carried out several experiments on Cynara cardunculus L. var. altilis DC. Particularly, three cultivars were grown on a gardening soil added with Cd and Pb, on industrial soil containing Cd and Pb, and in hydroponics contaminated with the same metals. Different behaviors were observed under metal stress compared to the control plants, with some cultivar-specific responses. Although all cultivars could uptake significant amounts of metals, only C. cardunculus cv Spagnolo counteracted metal stress preserving chloroplast ultrastructure and cell morphology. Moreover, the same cultivar showed a significant increase in stomata number, with subsequent enhancement of gas exchanges and net photosynthesis. By contrast, in the other cultivars analyzed, Cd and Pb uptake were coupled to severe ultrastructural alterations, a decrease in life span, pigment content, stomata number and photosynthetic activity. Finally, the sequential elution technique on the three cultivars grown in hydroponics was carried out to establish the amount of metal fractions in the apoplast and symplast compartments. The results indicated that a low fraction of Cd and Pb was chelated by EDTA; therefore, a high quantity of metals could potentially reach the cytoplasm inducing all observed responses. Furthermore, a lower translocation factor for both metals was calculated in hydroponics compared to soil; this result support the idea that root hairs, developed in hydroponics only under metal stress, act as metal sequestration sites. Regarding air biomonitoring, the aim of my PhD project was to investigate new applicative aspects of the moss- and lichen-bags technique. Since numerous contributions exist focused on metal uptake, but few were directed to organic pollutants so far, I tested the ability of moss and lichen transplants exposed alive or oven-devitalized, to entrap PAHs (Polycyclic Aromatic Hydrocarbons) in summer and winter. The results indicate that lichen performed better than moss due to its thallus morphology storing and preserving the low molecular weight PAH fraction (not linked to PM) from photodegradation, especially in summer. In addition, oven devitalization did not affect PAH accumulation, since both biomonitors spent their life mainly in cryptobiosis, even when exposed alive and sprayed with water; by contrast, devitalization, lowering PAH pre-exposure content allowed to estimate even low pollution levels. The other experiments on biomonitoring of air quality were carried out at Antwerp University, in the laboratory of prof. Roeland Samson. Moss bags have been used since '70s, and are regarded as a useful, versatile tool for biomonitoring of air quality, but almost all published papers concern exposure in fixed points in open air. Therefore, the novelty of my research was to investigate indoor metal pollution and metal uptake in moss-bags exposed in moving systems (bicycles). In both experiments I evaluated moss metal contents by ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) and magnetic properties of moss by saturated isothermal remanent magnetization (SIRM). The indoor-outdoor moss-bags exposure, carried out in parallel at Naples and Antwerp, showed outdoor element concentrations were significantly higher than indoors, and that most of indoor pollution derived from outdoor sources, even if some elements (e.g., Ni and Ti) were related to specific indoor fonts (e.g., cooking and house cleaning products). The short residence time (8-12h), prevalent in Belgium, lowered the ventilation frequency by opening windows, preserving indoor environments from outdoor metal contamination. Bike experiments carried out by six volunteers plus me in Antwerp, demonstrated that moss bags could entrap PM and related elements, when exposed in moving systems. Their well-known ability to discriminate specific land use classes was confirmed, since different metal uptakes and fluxes were observed along green, urban and industrial routes. Furthermore, daily flux calculation evidenced an exposure to air metal pollution 10-25 folds higher in moving systems compared to fixed positions (comparison with fixed outdoor exposure points). In both experimental designs, SIRM proved a useful, sample-conservative method for predicting metal-pollution level before chemical analysis. The evaluation of air quality outdoors, indoors and in fixed and moving conditions can provide a complete picture of human exposure to atmospheric elemental pollution.


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