May the Diversity of Epiphytic Lichens Be Used in Environmental Forensics?

Nature-based solutions for monitoring the impact of vehicular particulate matter and for the preventive conservation of the Palatine Hill archaeological site in Rome, Italy

Magnetic and chemical biomonitoring methodologies were applied to the southern slopes of the Palatine Hill archaeological area in Rome, Italy. Plant leaves and lichen transplants were respectively sampled and exposed between July 2022 and June 2023 to assess the impact of vehicular particulate matter from Via dei Cerchi, a trafficked road coasting Circus Maximus, towards the archaeological area upon the Palatine Hill. The magnetic properties of leaves and lichens, inferred from magnetic susceptibility, hysteresis loops and first order reversal curves, were combined with the concentration of trace elements. It was demonstrated that the bioaccumulation of magnetite-like particles, associated with tracers of vehicular emissions, such as Ba and Sb, decreased with longitudinal distance from the road, without any important influence of elevation from the ground. Lichens demonstrated to be more efficient biomonitors of airborne PM than leaves, irrespective of the plant species. Conversely, leaves intercepted and accumulated all PM fractions, including road dusts and resuspended soil particles. Thus, plant leaves are suitable for providing preventive conservation services that limit the impact of particulate pollution on cultural heritage sites within busy metropolitan contexts.

Use of lichens as bioindicators of contamination by agrochemicals and metals

The presence or absence of lichens serves as an indicator of the condition of an ecosystem and the degree to which it is contaminated by various agents, such as agrochemicals and metals. Evaluating the use of lichens as bioindicators of agrochemical contamination could provide a more comprehensive perspective of current contamination levels. Monitoring was conducted over a 4-month period in two study areas: one was a well-conserved area contaminated by metals, and the other was an area surrounded by agricultural crops contaminated by agrochemicals. Data on the presence and abundance of lichens in each study area were recorded at 10 monitoring points, a procedure that was repeated 16 times (every 15 days), and concentrations of heavy metals and "organophosphate" agrochemicals in the lichens collected were measured by means of Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-OES) and Gas Chromatography (GC), respectively. Generalized linear mixed models were used to assess abundance and richness, while general linear mixed models were used to attain Shannon diversity and Simpson dominance indices. Moreover, a multivariate analysis was performed in order to compare the lichen communities in both areas. The results indicated differences between the area contaminated by metals and that contaminated by agrochemicals in terms of abundance and Simpson's dominance index, while no differences were found in the case of the richness and diversity models. The PERMANOVA analysis additionally showed differences between the lichen communities in the two areas. The results also demonstrated that Canoparmelia caroliniana bioaccumulated metals in both areas. The levels of barium, cadmium, and sodium were higher in the area contaminated by metals, while concentrations of chromium and copper were higher in the area contaminated by agrochemicals. Finally, the concentrations of agrochemicals were higher in the area contaminated by agrochemicals and included toxic substances such as Methylparathion and Parathion, which are prohibited in Ecuador. In conclusion, this research underscores the importance of lichens as precise indicators of environmental health and contamination by agrochemicals and metals.

Physiological alterations and heavy metal accumulation in the transplanted lichen Pyxine cocoes (Sw.) Nyl. in Lucknow city, Uttar Pradesh

Air pollution has become a major concern due to its detrimental effects on living beings. The present study is aimed at assessing the current status of air pollution in Lucknow city using lichen transplantation technique and assesing its effect on physiology of Pyxine cocoes. The samples of P. cocoes were collected from relatively pollution-free area Malihabad and transplanted in 10 designated sites in five regions for 30 days. Various parameters such as heavy metals, chlorophyll pigments, carotenoid, chlorophyll degradation, and electrolyte conductivity were estimated in transplanted lichens. The study revealed that the concentration of all 10 heavy metals was higher in all transplanted samples than in the control sample, which was found in order of Al > Fe > Mn > Zn > Cu > Cr > Pb > Ni > Co > Cd. Among all 10 transplanted sites, the significantly increased accumulation of aluminum (5.11 to 5.47 µg L-1), iron (4.73 to 5.46 µg L-1), manganese (110.99 to 144.58 µg g-1), and zinc (87.96 to 97.40 µg g-1) was found in Charbagh, Qaisarbagh, and Alambagh sites. Further, in all samples, chlorophyll a (3.98 µg L-1), chlorophyll b (1.22 µg L-1), total chlorophyll (5.20 µg L-1), and chlorophyll degradation (0.55 µg g-1) were significantly decreased, whereas elevated levels of carotenoid (0.71 µg g-1), and electrolyte conductivity (64.99 µS cm-1), were observed. The scanning electron microscope (SEM) investigated the morphological changes in transplanted lichen samples, and significant damage to the anatomy of mycelium was found in most of the polluted site's samples, which correlated with the pollution levels. The present study clearly demonstrated that the transplanted lichen P. cocoes is an efficient bioaccumulator and bioindicator of air quality in urban environments.

Using plants in forensics: State-of-the-art and prospects

The increasing use of plant evidence in forensic investigations gave rise to a powerful new discipline - Forensic Botany - that analyses micro- or macroscopic plant materials, such as the totality or fragments of an organ (i.e., leaves, stems, seeds, fruits, roots) and tissue (i.e., pollen grains, spores, fibers, cork) or its chemical composition (i. e., secondary metabolites, isotopes, DNA, starch grains). Forensic botanists frequently use microscopy, chemical analysis, and botanical expertise to identify and interpret evidence crucial to solving civil and criminal issues, collaborating in enforcing laws or regulations, and ensuring public health safeguards. The present work comprehensively examines the current state and future potential of Forensic Botany. The first section conveys the critical steps of plant evidence collection, documentation, and preservation, emphasizing the importance of these initial steps in maintaining the integrity of the items. It explores the different molecular analyses, covering the identification of plant species and varieties or cultivars, and discusses the limitations and challenges of these techniques in forensics. The subsequent section covers the diversity of Forensic Botany approaches, examining how plant evidence exposes food and pharmaceutical frauds, uncovers insufficient or erroneous labeling, traces illegal drug trafficking routes, and combats the illegal collection or trade of protected species and derivatives. National and global security issues, including the implications of biological warfare, bioterrorism, and biocrime are addressed, and a review of the contributions of plant evidence in crime scene investigations is provided, synthesizing a comprehensive overview of the diverse facets of Forensic Botany.

Forensic botany: who?, how?, where?, when?

Plants are a good source of biological forensic evidence; this is due to their ubiquity, their ability to collect reference material, and their sensitivity to environmental changes. However, in many countries, botanical evidence is recognised as being scientifically. Botanical evidence is not mostly used for perpertration, instead it tends to serve as circumstantial evidence. Plant materials constitute the basis, among others, for linking a suspect or object to a crime scene or a victim, confirming or not confirming an alibi, determining the post-mortem interval, and determining the origin of food/object. Forensic botany entails field work, knowledge of plants, understanding ecosystem processes, and a basis understaning of geoscience. In this study, experiments with mammal cadavers were conducted to determine the occurence of an event. The simplest criterion characterising botanical evidence is its size. Therefore, macroremains include whole plants or their larger fragments (e.g. tree bark, leaves, seeds, prickles, and thorns), whereas microscopic evidence includes palynomorphs (spores and pollen grains), diatoms, and tissues. Botanical methods allow for an analysis to be repeated multiple times and the test material is easy to collect in the field. Forensic botany can be supplemented with molecular analyses, which, although specific and sensitive, still require validation.

Unraveling the ameliorative potentials of native lichen Pyxine cocoes (Sw.) Nyl., during COVID 19 phase

Due to the rapid increase in the novel coronavirus virulence, the entire world implemented the practice of lockdown along with the constraint of human movement. The obligation of quarantine halted most of the commercial and industrial movement that prominently disturbed the distinct key environmental parameters directly associated with the plant's and animal's health conditions. In this regard, the research aims to study the sudden shut-off of vehicular activity impact on the naturally growing lichen of the genus Pyxine cocoes. The results showed an increase in the pigments, Fv/Fm ratio, and phytohormones during the lockdown and concurrently the decreasing levels in the post-lockdown period. Interestingly, modulations in the phytohormones occur in the lockdown period as compared to the post-lockdown period. The metals Al, Cr, and Fe show the highest increasing trends in the unlocking period, whereas As, Cd, Pb, Cu, Hg, Mn, and Zn show very little variation during the running and post-lockdown phases. The lichen photosynthetic activity justifies further examination as initial biological indicators of the abrupt environmental variations prompted by such types of atmospheric situations and, to a greater extent, for the risk assessment in the near future. In conclusion, stress-phytohormone and amino acids play a significant role as stress reducers. Although lichens are well known for long environmental assessment, the present study will provide qualitative and quantitative variation in physiochemical changes in the short term and sudden environmental fluctuations. HIGHLIGHTS: • Qualitative and quantitative variation in biochemical parameters in lichen during and post-lockdown period was analyzed. • Stress-phytohormone and amino acids play a significant role as stress reducers. • Selectivity sequence reflection in heavy metal accumulation may be used in future studies.

The Genus Cetraria s. str.-A Review of Its Botany, Phytochemistry, Traditional Uses and Pharmacology

The genus Cetraria s. str. (Parmeliaceae family, Cetrarioid clade) consists of 15 species of mostly erect brown or greenish yellow fruticose or subfoliose thallus. These Cetraria species have a cosmopolitan distribution, being primarily located in the Northern Hemisphere, in North America and in the Eurasia area. Phytochemical analysis has demonstrated the presence of dibenzofuran derivatives (usnic acid), depsidones (fumarprotocetraric and protocetraric acids) and fatty acids (lichesterinic and protolichesterinic acids). The species of Cetraria, and more particularly Cetraria islandica, has been widely employed in folk medicine for the treatment of digestive and respiratory diseases as decoctions, tinctures, aqueous extract, and infusions. Moreover, Cetraria islandica has had an important nutritional and cosmetic value. These traditional uses have been validated in in vitro and in vivo pharmacological studies. Additionally, new therapeutic activities are being investigated, such as antioxidant, immunomodulatory, cytotoxic, genotoxic and antigenotoxic. Among all Cetraria species, the most investigated by far has been Cetraria islandica, followed by Cetraria pinastri and Cetraria aculeata. The aim of the current review is to update all the knowledge about the genus Cetraria covering aspects that include taxonomy and phylogeny, morphology and distribution, ecological and environmental interest, phytochemistry, traditional uses and pharmacological properties.

Assessing the impact of vehicular particulate matter on cultural heritage by magnetic biomonitoring at Villa Farnesina in Rome, Italy

Magnetic biomonitoring methodologies were applied at Villa Farnesina, Rome, a masterpiece of the Italian Renaissance, with loggias frescoed by renowned artists such as Raffaello Sanzio. Plant leaves were sampled in September and December 2020 and lichen transplants were exposed from October 2020 to early January 2021 at increasing distances from the main trafficked road, Lungotevere Farnesina, introducing an outdoor vs. indoor mixed sampling design aimed at assessing the impact of vehicular particulate matter (PM) on the Villa Loggias. The magnetic properties of leaves and lichens - inferred from magnetic susceptibility values, hysteresis loops and first order reversal curves - showed that the bioaccumulation of magnetite-like particles, associated with trace metals such as Cu, Ba and Sb, decreased exponentially with the distance from the road, and was mainly linked to metallic emission from vehicle brake abrasion. For the frescoed Halls, ca. 30 m from the road, the exposure to traffic-related emissions was very limited or negligible. Tree and shrub leaves of the Lungotevere and of the Villa's Gardens intercepted much traffic-derived PM, thus being able to protect the indoor cultural heritage and providing an essential conservation service. It is concluded that the joint use of magnetic and chemical analyses can profitably be used for evaluating the impact of particulate pollution on cultural heritage within complex metropolitan contexts as a preventive conservation measure.

Contrasting Patterns of Climatic Niche Divergence in Trebouxia-A Clade of Lichen-Forming Algae

Lichen associations are overwhelmingly supported by carbon produced by photosynthetic algal symbionts. These algae have diversified to occupy nearly all climates and continents; however, we have a limited understanding of how their climatic niches have evolved through time. Here we extend previous work and ask whether phylogenetic signal in, and the evolution of, climatic niche, varies across climatic variables, phylogenetic scales, and among algal lineages in Trebouxia—the most common genus of lichen-forming algae. Our analyses reveal heterogeneous levels of phylogenetic signal across variables, and that contrasting models of evolution underlie the evolution of climatic niche divergence. Together these analyses demonstrate the variable processes responsible for shaping climatic tolerance in Trebouxia, and provide a framework within which to better understand potential responses to climate change-associated perturbations. Such predictions reveal a disturbing trend in which the pace at which modern climate change is proceeding will vastly exceed the rate at which Trebouxia climatic niches have previously evolved.

Lichens as monitors of the atmospheric deposition of potentially toxic elements in high elevation Mediterranean ecosystems

In this study we used a terricolous lichen (Cetraria islandica) as bioaccumulator of potentially toxic elements (PTEs) to explore spatial patterns of air pollutant deposition along elevational gradients in the Majella Massif (Italy). Samples of C. islandica were collected at 200 m intervals along 6 transects from 1600 to 2600 m, both along the eastern and the western slope of the Majella massif, and analyzed for their PTE content. The results supported the hypothesis that the deposition of PTEs to the Majella massif is largely influenced by elevation and slope. Two main patterns emerged connected either with local soil erosion and long-range atmospheric transport. For some PTEs, namely Al, Cr, Li, Mg, in the absence of any other data, it is supposed that the anthropogenic input is very small compared to the natural input from weathering processes. In contrast, the group of air pollutants subjected to long-range transport, as in the case of Cd, Hg, and Pb, has very limited local input and the main sources responsible for the higher concentrations on the eastern slope are probably to be searched in the Balkan area.

Influence of washing thalli on element concentrations of the epiphytic and epilithic lichen Parmotrema tinctorum in the tropic

To enhance the reliability of active biomonitoring of air pollution using lichens, we tested how a water-washing procedure influences element concentrations in lichens growing on bark and rock substrates. Thalli of the lichen Parmotrema tinctorum were collected from tree bark and sandstones from a relatively clean air site in Khao Yai National Park, Thailand. After dry cleaning, each thallus was divided equally: the first part was directly used for element analysis, and the second part was washed with deionized water before it was sent for element analysis. The concentrations of 13 elements, including Al, As, Ca, Cu, Fe, K, Mg, Mn, Se, Sr, Ti, V, and Zn, were determined using inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the washing procedure substantially decreased the amounts of most elements in the lichens; after washing, concentrations of the elements in the epiphytic thalli showed decreases ranging from 17 to 81% (54% on average), and those in the epilithic thalli showed decreases ranging from 10 to 27% (18% on average). The coefficient of variation (CV) was also reduced for most elements, especially for those in the epiphytic thalli, indicating that washing could produce more homogeneous samples. All elements from the unwashed samples had higher contents in the epiphytic thalli than in the epilithic thalli, but the element contents were higher in the epilithic thalli after washing. Most elements in the washed epiphytic and epilithic thalli were not comparable, indicating that the washing procedure did not produce the same order of magnitude of element contents in the epiphytic and epilithic thalli. Based on the results of this study, we recommend washing pre-exposed lichen samples for more reliable results in active biomonitoring studies of air pollution.

The use of Parmotrema tinctorum (Parmeliaceae) as a bioindicator of air pollution

Abstract Air quality monitoring by automatic stations, although efficient, does not allow evaluating the effects of pollution on living organisms and communities. Thus, the aim of the present study was to use lichens of the Parmotrema tinctorum species in active air quality biomonitoring. We used a new methodology of chlorosis area analyses in QGis software, as low-cost and complementary tool to physicochemical methods. Samples of the aforementioned species were exposed to atmospheric pollution for 30 consecutive days in the dry and rainy seasons, in urban and industrial regions. The chlorosis rate (34% of the lichen thalli, on average) and the accumulation of sulfur (1.1 g.kg-1, on average) were higher in the samples of lichens exposed in the industrial region, in the dry season. There was a moderate-to-high positive correlation between chlorosis rate and lichen content of nitrogen, sulfur, iron and zinc, in the dry season, mainly with sulfur (r = 0.71). The results confirmed the sensitive of P. tinctorum to atmospheric pollution, even after a short exposure time. Such new active biomonitoring methodology (chlorosis analysis in the QGis) can be used in future studies of air quality assessment by environmental and health surveillance managers.

Disentangling sources of trace element air pollution in complex urban areas by lichen biomonitoring. A case study in Milan (Italy)

In this study we investigated the bioaccumulation of selected trace elements in lichen samples transplanted for three months in Milan, Italy, with the aim of assessing the main environmental contaminants and the overall pollution load, and of disentangling the main air pollution sources as well as of estimating fluxes of element deposition. The results highlighted Cu and Sb as important contaminants and suggested a common origin for these two elements from railways and non-exhaust sources of vehicular traffic such as brake abrasion. High or very high global air pollution emerged for all study sites. Source apportionment outlined three main factors, that found reliable correlation with distance from major roads and railways, an industrial plant, and soil resuspension. Ranges of estimated mean annual element deposition rates in the study area were similar to those reported for other cities.

Can Chitin and Chitosan Replace the Lichen Evernia prunastri for Environmental Biomonitoring of Cu and Zn Air Contamination?

This study compared the ability of the lichen Evernia prunastri, chitin and chitosan to take up Cu²⁺ and Zn²⁺. It was hypothesized that chitin and chitosan have an accumulation capacity comparable to the lichen, so that these biopolymers could replace the use of E. prunastri for effective biomonitoring of Cu and Zn air pollution. Samples of the lichen E. prunastri, as well as chitin (from shrimps) and chitosan (from crabs), were incubated with Cu and Zn solutions at concentrations of 0 (control), 10, 25, 50, 75, and 100 µM and analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Metal concentrations accumulated by lichen, chitin and chitosan samples were strongly and linearly correlated with the concentrations in the treatment solutions. The lichen always showed significantly higher accumulation values compared to chitin and chitosan, which showed similar accumulation features. The outcomes of this study confirmed the great effectiveness of the lichen Evernia prunastri for environmental biomonitoring and showed that chitin and chitosan have a lower accumulation capacity, thus suggesting that although these biopolymers have the potential for replacing E. prunastri in polluted areas, their suitability may be limited in areas with intermediate or low pollution levels.

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

The concentration of selected trace elements and the magnetic properties of samples of the lichen Evernia prunastri exposed for 3 months in Milan (Italy) were investigated to test if magnetic properties can be used as a proxy for the bioaccumulation of chemical elements in airborne particulate matter. Magnetic analysis showed intense properties driven by magnetite-like minerals, leading to significant correlations between magnetic susceptibility and the concentration of Fe, Cr, Cu, and Sb. Selected magnetic particles were characterized by Scanning Electron Microscope and Energy Dispersion System microanalyses, and their composition, morphology and grain size supported their anthropogenic, non-exhaust origin. The overall combination of chemical, morphoscopic and magnetic analyses strongly suggested that brake abrasion from vehicles is the main source of the airborne particles accumulated by lichens. It is concluded that magnetic susceptibility is an excellent parameter for a simple, rapid and cost-effective characterization of atmospheric trace metal pollution using lichens.

Spatial distribution of mercury and other potentially toxic elements using epiphytic lichens in Nova Scotia

The use of naturally occurring epiphytic lichens can be an effective tool for regional monitoring of mercury (Hg) and other potentially toxic elements (PTEs). Nova Scotia, Canada is a hotspot for mercury and other trace metal accumulation in ecosystems; partially attributed to long-range transport of air pollution. The relative contribution of local and international sources of Hg to local air in Nova Scotia is unknown. This study assessed the potential of epiphytic lichens (Usnea spp.) as passive samplers for PTE air pollution in Nova Scotia. Lichens (n = 190) collected across mainland Nova Scotia were analyzed for PTEs. Results indicate that there are 3 distinct clusters of PTEs which suggest patterns and sources for each elemental cluster. Hg was correlated with longitude and prevailing wind direction, and Hg was not significantly different in site-specific hotspot sampling nor year of sampling. Our data support the hypothesis that Hg in lichens is from historical and ongoing long-range transport and diffuse emission patterns rather than localized pollution sources. PTE concentrations were shown to have median values that are similar to other remote regions (such as the Antarctic) however the maximum values were observed to be substantially higher for some elements (e.g. lead, cadmium). This research supports the use of lichens as biomonitors and provides a baseline for future monitoring efforts to identify changes in PTE distribution in Nova Scotia with ongoing industrial activity and a changing climate.

Lichen Diversity and Biomonitoring: A Special Issue

Lichens are symbiotic organisms susceptible to environmental alteration due to their morphological and physiological features. For this reason, researchers and decision-makers are extensively using lichen biomonitoring for assessing the effects of various anthropogenic disturbances. The Special Issue was launched to fulfil some knowledge gaps in this field, such as the development of procedures to interpret and compare results. The SI includes three reviews that explore the application of lichen biomonitoring for detecting the effects of climate change. Three articles and one review paper examined the use at a decision level of biomonitoring of air pollution employing lichens, including the application in environmental forensic. Finally, six research articles are illustrative examples of lichen biomonitoring in poorly known habitats, providing data from the physiological to the community level of observation, and pose the basis for extending comparable approaches on a global scale.

Current knowledge on Parmelia genus: Ecological interest, phytochemistry, biological activities and therapeutic potential

Parmelia Acharius is one of the most representative genera within Parmeliaceae family which is the largest and the most widespread family of lichen-forming fungi. Parmelia lichens present a medium to large foliose thallus and they are distributed from the Artic to the Antartic continents, being more concentrated in temperate regions. According to its current description, the genus encompasses up to 41 different species and it is phylogenetically located within the Parmelioid clade (the largest group in the family). Interestingly, some of its species are among the most common epiphytic lichens in Europe such as Parmelia sulcata Taylor and Parmelia saxatilis (L.) Ach. The present work aims at providing a complete overview of the existing knowledge on the genus, from general concepts such as taxonomy and phylogeny, to their ecological relevance and biological interest for pharmaceutical uses. As reported, Parmelia lichens arise as valuable tools for biomonitoring environmental pollution due to their capacity to bioaccumulate metal elements and its response to acid rain. Moreover, they produce a wide array of specialized products/metabolites including depsides, depsidones, triterpenes and dibenzofurans, which have been suggested to exert promising pharmacological activities, mainly antimicrobial, antioxidant and cytotoxic activities. Herein, we discuss past and recent data regarding to the phytochemical characterization of more than 15 species. Even though the knowledge is still scarce in comparsion to other groups of organisms such as higher plants and other non-lichenized fungi. Reviewed works suggest that Parmelia lichens are worthy of further research for determining their actual possibilities as sources of bioactive compounds with potential therapeutic applications.

Do Different Teams Produce Different Results in Long-Term Lichen Biomonitoring?

Lichen biomonitoring programs focus on temporal variations in epiphytic lichen communities in relation to the effects of atmospheric pollution. As repeated surveys are planned at medium to long term intervals, the alternation of different operators is often possible. This involves the need to consider the effect of non-sampling errors (e.g., observer errors). Here we relate the trends of lichen communities in repeated surveys with the contribution of different teams of specialists involved in sampling. For this reason, lichen diversity data collected in Italy within several ongoing biomonitoring programs have been considered. The variations of components of gamma diversity between the surveys have been related to the composition of the teams of operators. As a major result, the composition of the teams significantly affected data comparability: Similarity (S), Species Replacement (R), and Richness Difference (D) showed significant differences between “same” and “partially” versus “different” teams, with characteristics trends over time. The results suggest a more careful interpretation of temporal variations in biomonitoring studies.