Magnetic properties and element concentrations in lichens exposed to airborne pollutants released during cement production

Abstract

The content of selected elements (Al, As, Ca, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, S, Ti, V and Zn) was measured in samples of the lichen Evernia prunastri exposed for 30, 90 and 180 days around a cement mill, limestone and basalt quarries and urban and agricultural areas in SW Slovakia. Lichens transplanted around the investigated quarries and the cement mill rapidly (30 days) reflected the deposition of dust-associated elements, namely Ca (at the cement mill and the limestone quarry) and Fe, Ti and V (around the cement mill and the basalt quarry), and their content remained significantly higher throughout the whole period (30-180 days) with respect to the surrounding environment. Airborne pollutants (such as S) progressively increased in the study area from 30 to 180 days. The magnetic properties of lichen transplants exposed for 180 days have been characterized and compared with those of native lichens (Xanthoria parietina) and neighbouring bark, soil and rock samples, in order to test the suitability of native and transplanted samples as air pollution magnetic biomonitors. The magnetic mineralogy was homogeneous in all samples, with the exception of the samples from the basalt quarry. The transplants showed excellent correlations between the saturation remanent magnetization (Mrs) and the content of Fe. Native samples had a similar magnetic signature, but the values of the concentration-dependent magnetic parameters were up to two orders of magnitude higher, reflecting higher concentrations of magnetic particles. The concentrations of As, Ca and Cr in lichens correlated with Mrs values after neglecting the samples from the basalt quarry, which showed distinct magnetic properties, suggesting the cement mill as a likely source. Conversely, Ti and Mn were mostly (but not exclusively) associated with dust from the basalt quarry. It is suggested that the natural geological characteristics of the substrate may strongly affect the magnetic properties of lichen thalli. Taking this into account, the results of this study point out the suitability of lichens as air pollution magnetic biomonitors.

Biomineralization in saxicolous lichens: Raman spectroscopic study supported with XRF and SEM-EDX analyses

“…Therefore, calcium is coming from an environmental source, probably as calcite particles that deposit on the lichen surface and are incorporated to the metabolism. The discussion on the atmospheric intake of calcite particles by diverse lichen genera is not a novelty, [14,34] but in the authors' knowledge, the distribution of the biominerals related with this process on the lichen-support interface has not been described up to now by means of Raman spectroscopy.…”

Magnetic Emissions from Brake Wear are the Major Source of Airborne Particulate Matter Bioaccumulated by Lichens Exposed in Milan (Italy)

“…Transplants of the same lichen species exposed for 2 months in an industrial area showed values in the range 0.4 to 7.4 × 10 −8 m 3 /kg −1 [46]. Transplants of Evernia prunastri exposed for 6 months around a cement production plant in Slovakia showed magnetic susceptibility ranging 1.3 to 8.1 × 10 −8 m 3 /kg −1 [47]. Bags of Parmotrema pilosum exposed to atmospheric pollutants over the course of 1 year increased from an initial mass-specific magnetic susceptibility value (mean ± S.D.)…”

Biomagnetic Monitoring of Atmospheric Pollution: A Review of Magnetic Signatures from Biological Sensors

“…Magnetic properties have been reported recently of terrestrial mosses and lichens 116,136,137 and moss bags 41,127,135,[138][139][140][141] . Because of their high accumulation capacity and high surface:volume ratio, mosses and lichens are suitable for magnetic evaluation of environmental pollution 116 .…”