title: NIR spectroscopy as a tool for discriminating between lichens exposed to air pollution.
abstract: Lichens are used as biomonitors of air pollution because they are extremely sensitive to the presence of substances that alter atmospheric composition. Fifty-one thalli of two different varieties of Pseudevernia furfuracea (var. furfuracea and var. ceratea) were collected far from local sources of air pollution. Twenty-six of these thalli were then exposed to the air for one month in the industrial port of Genoa, which has high levels of environmental pollution. The possibility of using Near-infrared spectroscopy (NIRS) for generating a 'fingerprint' of lichens was investigated. Chemometric methods were successfully applied to discriminate between samples from polluted and non-polluted areas. In particular, Principal Component Analysis (PCA) was applied as a multivariate display method on the NIR spectra to visualise the data structure. This showed that the difference between samples of different varieties was not significant in comparison to the difference between samples exposed to different levels of environmental pollution. Then Linear Discriminant Analysis (LDA) was carried out to discriminate between lichens based on their exposure to pollutants. The distinction between control samples (not exposed) and samples exposed to the air in the industrial port of Genoa was evaluated. On average, 95.2% of samples were correctly classified, 93.0% of total internal prediction (5 cross-validation groups) and 100.0% of external prediction (on the test set) was achieved.
authors.affiliation: University of Genoa, Department of Pharmacy, Via Brigata Salerno, 13, I-16147 Genoa, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Casale
authors.affiliation: University of Genoa, Department of Pharmacy, Via Brigata Salerno, 13, I-16147 Genoa, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Bagnasco
authors.affiliation: University of Genoa, Department of Pharmacy, Via Brigata Salerno, 13, I-16147 Genoa, Italy. Electronic address: giordani@difar.unige.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: Giordani
authors.affiliation: University of Genoa, Department of Earth Sciences, Environment and Life (DISTAV), Corso Europa, 26, I-16126 Genoa, Italy.
authors.forename: Mauro Giorgio
authors.initials: MG
authors.lastname: Mariotti
authors.affiliation: University of Genoa, Department of Earth Sciences, Environment and Life (DISTAV), Corso Europa, 26, I-16126 Genoa, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Malaspina
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D000397:Air Pollution / Q000032:analysis / Q000706:statistics & numerical data; D004784:Environmental Monitoring / Q000379:methods*; D008011:Lichens / Q000737:chemistry*; D025341:Principal Component Analysis; D019265:Spectroscopy, Near-Infrared
chemical_list: D000393:Air Pollutants
keywords: Air pollution; Chemometrics; Lichens; NIR spectroscopy