Effects of acute NH3 air pollution on N-sensitive and N-tolerant lichen species

Abstract

Lichens are sensitive to the presence of ammonia (NH3) in the environment. However, in order to use them as reliable indicators in biomonitoring studies, it is necessary to establish unequivocally the occurrence of certain symptoms following the exposure to NH3 in the environment. In this paper, we simulated an episode of acute air pollution due to the release of NH3. The biological effects of acute air pollution by atmospheric NH3 have been investigated using N-sensitive (Flavoparmelia caperata) and N-tolerant (Xanthoria parietina) species. Lichen samples were exposed to ecologically relevant NH3 concentrations for 8 weeks, simulating three areas of impact: a control area (2 μg/m(3)), an area of intermediate impact (2-35 μg/m(3)) and an area of high impact (10-315 μg/m(3)), with a peak of pollution reached between the fourth and fifth week. Ammonia affected both the photobiont and the mycobiont in F. caperata, while in X. parietina only the photosynthetic performance of the photobiont was altered after exposure to the highest concentration. In the photobiont of F. caperata we recorded chlorophyll degradation as indicated by OD435/415 ratio, decrease of the photosynthetic performance (as reflected by the maximum quantum yield of primary photochemistry FV/FM and the performance index PIABS); in the mycobiont, ergosterol reduction, membrane lipid peroxidation (as reflected by the increase of thiobarbituric acid reactive substances), alteration (decrease) of the secondary metabolite usnic acid. No effects were detected on caperatic acid and dehydrogenase activity. In X. parietina, the only signal determined by NH3 was the alteration of FV/FM and the performance index PIABS. The results suggest that physiological parameters in N-sensitive lichens well reflect the effects of NH3 exposure and can be applied as early indicators in monitoring studies.

More tolerant than expected: Taking into account the ability of Cladonia portentosa to cope with increased nitrogen availability in environmental policy

“…Lichen functional groups, defined as groups of species with a similar response to specific environmental factors (Lavorel et al, 2002), are widely used as a monitoring tool (e.g. Benítez et al, 2018;Paoli et al, 2015). The attribution of a species to a certain functional group usually reflects an expert-assessment based on data available in the literature (for ex.…”

The Impact of Nitrogen Pollution in the Agricultural Landscape on Lichens: A Review of Their Responses at the Community, Species, Biont and Physiological Levels

“…The main sources of nitrogen in the agricultural landscape are ammonia (NH 3 ) and the ammonium cation (NH 4 + ). Agricultural activities, principally livestock farming, the application of organic and mineral fertilizers, and biomass burning, contribute significantly to emissions of these compounds [5][6][7][8][9][10][11][12].…”

“…Those authors demonstrated the sensitivity of photosystem II to this N pollutant; a marked decrease in the potential quantum yield of PSII was detected in thalli exposed near a sheep farm [9]. The sensitivity of the photobiont in Flavoparmelia caperata to N pollution was manifested by chlorophyll degradation and diminished photosynthetic performance, whereas in Xanthoria parietina, only the highest concentration affected the autotroph [10]. Under the impact of ammonium nitrate (NH 4 NO 3 ), the photobiont of Cladonia arbuscula ssp.…”

Mechanisms of nitrogen deposition effects on temperate forest lichens and trees

“…Depending on the species ( Johansson et al 2011 , Paoli et al 2015 ) and certain climate factors, the acidification of pigments from increasing N deposition (in the form of NH 4 + , NO 3 − , and organic N) can harm lichens’ photosynthetic abilities and therefore their ability to capture energy and C ( Fig. 1 ).…”