NIR spectroscopy as a tool for discriminating between lichens exposed to air pollution

Area of Science:

• Environmental Science
• Analytical Chemistry
• Botany

Background:

• Lichens are sensitive bioindicators of atmospheric composition changes.
• Biomonitoring using lichens requires methods to detect pollution-induced alterations.

Purpose of the Study:

• To investigate Near-infrared spectroscopy (NIRS) for lichen-based air pollution biomonitoring.
• To assess the efficacy of chemometric methods in differentiating polluted and non-polluted lichen samples.

Main Methods:

• Collection of Pseudevernia furfuracea thalli from unpolluted and polluted (Genoa industrial port) areas.
• Analysis of lichen samples using Near-infrared spectroscopy (NIRS).
• Application of chemometric techniques, including Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA).

Main Results:

• NIRS combined with chemometrics successfully discriminated between lichen samples exposed to different pollution levels.
• Principal Component Analysis (PCA) indicated pollution exposure had a greater impact than varietal differences.
• Linear Discriminant Analysis (LDA) achieved high classification accuracy: 95.2% average, 93.0% internal cross-validation, and 100.0% external prediction.

Conclusions:

• NIRS offers a robust, non-destructive method for lichen biomonitoring of air pollution.
• Chemometric analysis of NIR spectra provides a reliable 'fingerprint' for assessing environmental pollution exposure in lichens.