Di Palma, Anna (2016) Mosses for monitoring air pollution: towards the standardization of moss-bag technique and the set-up of a new biomaterial. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Lingua: English
Title: Mosses for monitoring air pollution: towards the standardization of moss-bag technique and the set-up of a new biomaterial
Di Palma, Annaanna.dipalma@unina.it
Date: 31 March 2016
Number of Pages: 148
Institution: Università degli Studi di Napoli Federico II
Department: Agraria
Scuola di dottorato: Scienze agrarie e agro-alimentari
Dottorato: Agrobiologia e agrochimica
Ciclo di dottorato: 28
Coordinatore del Corso di dottorato:
Carputo, Domenicocarputo@unina.it
Date: 31 March 2016
Number of Pages: 148
Uncontrolled Keywords: biomonitoring; air pollution; mosses; moss-bags; cloned moss; moss characterization
Settori scientifico-disciplinari del MIUR: Area 07 - Scienze agrarie e veterinarie > AGR/13 - Chimica agraria
Area 05 - Scienze biologiche > BIO/03 - Botanica ambientale e applicata
Area 05 - Scienze biologiche > BIO/07 - Ecologia
Area 03 - Scienze chimiche > CHIM/01 - Chimica analitica
Date Deposited: 13 Apr 2016 14:29
Last Modified: 09 Nov 2016 08:58
URI: http://www.fedoa.unina.it/id/eprint/10899


The monitoring of the air quality by mosses provides qualitative and quantitative data using economic, easy-to-manage and eco-friendly methods. Due to peculiar morphological and physiological characteristics, mosses are very suitable adsorbents for a wide variety of pollutants (i.e. metals and metalloids, PAHs, radionuclides) and, when used as transplants in nylon bags, they allow an easy monitoring potentially of any site, with a highly dense sampling network. Nevertheless, the moss-bag technique, although widely applied, is still not based on standardized protocols. It follows that the data collected from biomonitoring surveys are not comparable, thus relegating the active biomonitoring exclusively to academic field or to scientific purposes. Moreover, there are not enough studies comparing bioaccumulation data with those obtained by estimation models or traditional monitoring approaches, neither it is clear how the moss-bag technique can discriminate pollution inputs on a very small scale and within areas relatively close to each other or characterized by different land uses. Another important issue is that the mosses employed as biomonitors are naturally grown species. The collection in nature implies an intrinsic variability of mosses in terms of elemental and chemical composition and, as a consequence, it poses a high degree of uncertainty in the interpretation of the results. Moreover, an uncontrolled harvesting of mosses could lead to a severe environmental impact. In this context, aims of this Doctoral Thesis are: 1) to test the variables affecting the exposure protocol in the view of a standard moss-bag method for the biomonitoring of air pollution; 2) to integrate biomonitoring results with emission data provided by inventories for the evaluation of the atmospheric pollution; 3) to characterize a novel moss biomaterial for biomonitoring purposes. For the standardization assay, more than one thousand moss bags were exposed contemporary in three European territories (Austria, Italy, Spain) belonging to three different climatic areas (Mediterranean, continental and oceanic). For each area, four distinct scenarios (background, urban, agricultural, industrial) were selected for the exposure, on the basis of their level and type of contamination. The moss included in bags was the Pseudoscleropodium purum (Hedw.) M. Fleisch, collected in a pristine area of the Galicia (NE Spain). Shoot apical parts were selected, EDTA-washed and finally devitalized by oven drying at 100 °C. For the first time, all the variables affecting the air pollutant uptake by moss exposed in bags were considered: 1) the moss bags characteristics (round, spherical and flat shapes; nylon net mesh size of 1, 2 and 4 mm; moss amount and moss weight/bag surface area ratio of 15, 30, 45 mg cm-2); 2) the exposure criteria (exposure time of 3, 6, 12 weeks; exposure heights of 4, 7, 10 m above ground); 3) the climatic conditions of the exposure area. The concentrations of metals and metalloids were determined by ICP mass spectrometry and the results were evaluated comparing pre- and post-exposure moss samples. Results showed that the amount of moss included in bags was the most important factor affecting the pollutant accumulation by mosses: the more the moss density inside bags increases, the less metal uptake occurs. The other variables (climate, bag size and shape, exposure time and height) had low or no influence at all. As consequence of the obtained results, the project Mossclone proposed the use of a standard moss bag, spherical-shaped, with a mesh size of 2 mm and filled with a moss amount less than 15 mg per cm2 of bag surface area. In addition, it was suggested to expose the moss-bags for not less than six weeks (to increase the detectability of metal concentrations in moss) and, for practical reasons, at 4 m above the ground. The proposed standardized protocol for moss-bag exposure was then tested in a biomonitoring campaign carried out in the framework of the LIFE-Ecoremed project, in order to assess the air quality of five municipalities belonging to the Italian RIPS “Litorale Domizio-Agro Aversano” (Campania Region, south Italy). In each municipality, two scenarios (urban and agricultural) and two sub-scenarios (a street side and a corresponding green area) were selected, in order to evaluate the anthropogenic pollution, with a particular attention to the vehicular traffic impact on the surrounding areas. The concentrations of twenty PAHs and of thirty-nine elements including rare earths were determined by ICP mass spectrometry in pre- and post-exposure samples of Hypnum cupressiforme Hedw. moss, treated and exposed following the standardized method. After exposure, the concentration of most of the elements and PAHs (in particular the 4- and 5-ringed PAHs) was significantly increased in moss material. The pollutants had a similar spatial distribution pattern over the entire study area, with road traffic and agricultural practices as the major diffuse pollution sources. Hypnum cupressiforme moss bags was able to detect airborne element and PAH inputs and to discriminate different pollution levels in a landscape characterized by a jeopardized structure in which agricultural and urban/residential sites are strictly mixed together. The data obtained in the Italian biomonitoring campaign were combined with those provided by emission inventories, which are a collection of estimations, recorded with spatial disaggregation, on the type, amount and emission sources of pollutants. As a result, it was observed that both approaches (biomonitoring and emission inventory) indicated the same most polluted municipality and a similar spatial pattern, in particular for lead. This suggests that the joint use of emission inventory and moss accumulation could be a valuable resource to reveal contaminants better than the use of a single approach, allowing a more deep investigation on the pollutant emission sources, especially for those contaminants not routinely monitored. To overcome the limits of the use of native mosses, the last part of the PhD thesis is focused on the characterization of a new moss biomaterial, provided by the cloning inside bioreactors. The cloned moss specie in question is the Sphagnum palustre L., whose elemental composition (pre- and post- treatments with EDTA and by devitalization) and molecular profile were given, in comparison with the conspecific field moss, in order to outline a defined fingerprint of the new biomaterial. The morphological and physico-chemical properties of the moss adsorbing surfaces were also examined by electron microscopy, in vitro experiments on metal adsorption and by the chemical analysis of the surface exchange sites. A field exposure test with moss-bags was performed, comparing the clone and the naturally grown P. purum. The clones exhibited a much lower metal concentration (from 10 to 100 times) in their tissues than the native samples, thus making the former better indicators of low metal loading. New DNA markers, also useful for systematic analyses of the Sphagnum genus, were provided in order to characterize and label the clone. The S. palustre clone exhibited acid base properties similar to those of naturally grown Sphagnum samples and showed a significantly higher metal uptake performance. Therefore, the use of this biomaterial, with very homogenous morphological and chemical characteristics and a remarkable metal uptake capability, is strongly recommended in the view of a rigorously standardized moss-bag protocol for the active monitoring of persistent atmospheric pollutants.

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