Determination of airborne trace elements in an urban area using lichens as biomonitor

A New Rare Halogenated Depside from Lichen and Study of its Anti-Proliferative Activity

Lichens are a symbiotic association of algae and fungus, belonging to the family Parmeliaceae. Some lichen species are edible and used as an active ingredient for preparation of exotic spices as well as folklore medicine to cure different kinds of ailments. A specimen of lichen was collected from Munner in the Kerala State of South India for chemical profiling. Chemical analyses of the diethyl ether extract of the defatted lichen led to the isolation of six phenols 1-6 with variation of relative abundance. Amongst them, the relative abundance of compound 3 was the greatest (1 % of crude extract) and it was identified as atranorin. The structures of known compounds were confirmed by comparison of their 1H-NMR, 13C NMR, and mass data with published values available in the literature. In vitro bioassay for anti-proliferative activity of these compounds has been conducted against various human cancer cell lines in comparison with paclitaxel as control using SRB assay. Interestingly, a new compound 5 was found along with previously reported compounds from this lichen. This new compound was designated as fluoroatranorin 5 which was reported for the first time herein. The structural characterization of a new depside was determined by spectral methods such as 1H-NMR, 13C NMR, 19F NMR, IR, LC-HRESI-MS, and LC-MS/MS study. Its structure was confirmed by single crystal X-ray diffraction study. This new compound was designated as fluoroatranorin 5 which was reported first time herein. Anti-proliferative activity of all these compounds was evaluated against six different cancer cell lines. The inhibitory activity, IC50 value of compounds 1-3 and 5 exhibited at 99.64, 102.04, 109.20, 53.0 and 2.4 μM on cancer cell lines HT-29 (colon), Hela (cervical), HT-29, HPAC (pancreas) and A2780 (ovarian cancer cell line) respectively in comparison with paclitaxel as control. The new compound 5 exhibited significant activity with IC50 value 2.4 μM on A2780 ovarian cancer cell line.

Lichen biomonitoring to assess spatial variability, potential sources and human health risks of polycyclic aromatic hydrocarbons (PAHs) and airborne metal concentrations in Manchester (UK)

Airborne metals and organic pollutants are linked to severe human health impacts, i.e. affecting the nervous system and being associated with cancer. Airborne metals and polycyclic aromatic hydrocarbons (PAHs) in urban environments are derived from diverse sources, including combustion and industrial and vehicular emissions, posing a threat to air quality and subsequently human health. A lichen biomonitoring approach was used to assess spatial variability of airborne metals and PAHs, identify potential pollution sources and assess human health risks across the City of Manchester (UK). Metal concentrations recorded in lichen samples were highest within the city centre area and along the major road network, and lichen PAH profiles were dominated by 4-ring PAHs (189.82 ng g-1 in Xanthoria parietina), with 5- and 6-ring PAHs also contributing to the overall PAH profile. Cluster analysis and pollution index factor (PIF) calculations for lichen-derived metal concentrations suggested deteriorated air quality being primarily linked to vehicular emissions. Comparably, PAH diagnostic ratios identified vehicular sources as a primary cause of PAH pollution across Manchester. However, local more complex sources (e.g. industrial emissions) were further identified. Human health risk assessment found a "moderate" risk for adults and children by airborne potential harmful element (PHEs) concentrations, whereas PAH exposure in Manchester is potentially linked to 1455 (ILCR = 1.45 × 10-3) cancer cases (in 1,000,000). Findings of this study indicate that an easy-to-use lichen biomonitoring approach can aid to identify hotspots of impaired air quality and potential human health impacts by airborne metals and PAHs across an urban environment, particularly at locations that are not continuously covered by (non-)automated air quality measurement programmes.

Spatial evaluation of air quality by biomonitoring of toxic element accumulation in lichens in urban green areas and nature parks on the Anatolian side of Istanbul

The city of Istanbul is constantly exposed to air pollution due to its high population, heavy traffic - sea and air transport - and urban industry. This study basically aims to determine the recent level of airborne heavy metals, using lichen biomonitoring method. The cosmopolitan foliose lichen Xanthoria parietina growing abundantly on trees was sampled from 16 urban green spaces in 8 districts on the Anatolian side of Istanbul. Multi-element analysis by ICP-MS was applied to measure the accumulation of 10 potentially toxic trace elements in lichen samples. Spatial distributions of element levels in the air in the sampling areas are shown by mapping. According to the analysis data, the sequence of element deposition levels in lichen samples was as follows; Al > Fe > Mn > Zn > Cr > Cu > Pb > V > Ni > As. Most of the measured atmospheric element amounts yielded results much higher than the reference material in all areas. It was detected that the highest pollution in terms of Al, Cu, Fe, Mn, and Ni elements was in Elmasburnu Nature Park area in Beykoz district, which is a touristic place by the sea. Changes in the city's air quality over the years have been evaluated by comparing element levels in these locations in a previous biomonitoring study and some differences were found. The resulting data is valuable for periodic monitoring of toxic elements in the air, for determining causes of air pollution, and for taking precautions.

Mercury Content and Amelioration of Its Toxicity by Nitric Oxide in Lichens

Mercury (Hg) content measured in five epiphytic lichen species collected in Slovakia mountain forests ranged from 30 to 100 ng/g DW and was species-specific, decreasing in the order Hypogymnia > Pseudevernia > Usnea > Xanthoria > Evernia prunastri (but polluted sites had no impact on Hg amount in Xanthoria). Evernia was therefore used to study the impact of short-term exogenous Hg (100 µM, 24 h) and possible amelioration of Hg toxicity by nitric oxide (NO) donor sodium nitroprusside (SNP). NO was efficiently released from SNP as detected by two staining reagents and fluorescence microscopy and reduced Hg-induced ROS signal and absorption of Hg by thalli of Evernia prunastri. At the same time, NO ameliorated Hg-induced depletion of metabolites such as ascorbic acid and non-protein thiols, but not of free amino acids. The amount of metabolites, including soluble phenols, was reduced by excess Hg per se. On the contrary, NO was unable to restore Hg-stimulated depletion of chlorophyll autofluorescence but mitigated the decline of some macronutrients (K and Ca). Data confirm that accumulation of Hg in the epiphytic lichens is species-specific and that NO is a vital molecule in Evernia prunastri that provides protection against Hg-induced toxicity with considerable positive impact on metabolic changes.

Biomonitoring Potentially Toxic Elements (PTEs) Using Lichen Transplant Usnea misaminensis: A Case Study from Malaysia

Urban air pollution has been a major concern due to its impact on global public health. Various techniques for monitoring urban air quality have been developed. However, there is currently a dearth of research on how effective bioaccumulators such as lichen are at monitoring urban air pollution. As a result, the purpose of this research is to investigate the use of U. misaminensis as a biological indicator for biomonitoring urban air quality in Malaysia. Three months were spent exposing lichen samples in three Malaysian cities (Kuala Lumpur, Penang, and Johor Bahru). The trace element content and vitality of the lichens were assessed. The results of this study revealed that U. misaminensis is an effective biological indicator for measuring 25 elements of air pollutants in metropolitan areas. They also revealed that all 25 elements accumulated in the urban area sample were greater than in the control sample. The vitality rate of lichens dropped in the urban area sample when compared with the control sample, indicating that an increase in elements in the air will impact the vitality rate of any biological component. In this study, two arguments are made: (a) Lichen is an excellent biological indicator, particularly for urban air pollutants such as potentially toxic elements; and (b) traffic is the primary contributor to urban air pollution; hence, the local government requires a better plan and design for urban areas to decrease air pollutants build-up.

Biomonitoring of airborne trace elements using transplanted lichens around a paper industry (Morelia, Mexico)

The deposition of trace elements around a pulp and paper industry in Morelia, Mexico, was evaluated using two lichen species as biomonitors. Samples of the foliose lichen Flavopunctelia praesignis and the fruticose lichen Usnea ceratina were collected in two remote areas and transplanted at different distances and directions from the pollution source. Lichen samples were exposed for 4 months (1) around the industrial area and (2) in their native habitats (control sites). We investigated the bioaccumulation of 11 trace elements in lichen thalli, and we compared the response of the two lichen species. To identify possible common sources, we evaluated the relationships between trace elements by correlations and cluster analyses. Our results showed that Cd was a good tracer for air pollution from the pulp and paper mills. In samples of Usnea ceratina exposed around the industrial area, Cd was significantly higher than in the remote area. Within the study area, trace element contents increase with the distance from the source, and they showed high depositions in the direction of prevailing winds. Moreover, we were able to detect groups of elements with similar behavior and common origins. Our results indicated that Flavopunctelia praesignis showed a higher capacity to accumulate trace elements than Usnea ceratina.

Spatial Distribution of Air Pollution, Hotspots and Sources in an Urban-Industrial Area in the Lisbon Metropolitan Area, Portugal-A Biomonitoring Approach

This study aimed to understand the influence of industries (including steelworks, lime factories, and industry of metal waste management and treatment) on the air quality of the urban-industrial area of Seixal (Portugal), where the local population has often expressed concerns regarding the air quality. The adopted strategy was based on biomonitoring of air pollution using transplanted lichens distributed over a grid to cover the study area. Moreover, the study was conducted during the first period of national lockdown due to COVID-19, whereas local industries kept their normal working schedule. Using a set of different statistical analysis approaches (such as enrichment and contamination factors, Spearman correlations, and evaluation of spatial patterns) to the chemical content of the exposed transplanted lichens, it was possible to assess hotspots of air pollution and to identify five sources affecting the local air quality: (i) a soil source of natural origin (based on Al, Si, and Ti), (ii) a soil source of natural and anthropogenic origins (based on Fe and Mg), (iii) a source from the local industrial activity, namely steelworks (based on Co, Cr, Mn, Pb, and Zn); (iv) a source from the road traffic (based on Cr, Cu, and Zn), and (v) a source of biomass burning (based on Br and K). The impact of the industries located in the study area on the local air quality was identified (namely, the steelworks), confirming the concerns of the local population. This valuable information is essential to improve future planning and optimize the assessment of particulate matter levels by reference methods, which will allow a quantitative analysis of the issue, based on national and European legislation, and to define the quantitative contribution of pollution sources and to design target mitigation measures to improve local air quality.

Characterization and source estimates of primary and secondary carbonaceous aerosols at urban and suburban atmospheres of Düzce, Turkey

Düzce is one of the cities located in the western Black Sea region of Turkey with a population of 377,610 in 2017 (TUIK, 2017). There is no satisfying scientific information available to address the contribution of primary and secondary sources of carbonaceous aerosols to the observed PM₁₀ levels in the city. The main objective of the study is to determine the levels and sources of carbonaceous aerosols in PM₁₀. For this purpose, PM₁₀ samples were collected at urban and suburban locations in Düzce during winter and summer season in 2015. Average summer OC and EC concentrations in the urban area were 9.5 and 1.3 μg m^-3, respectively, while the corresponding concentrations were observed as 28.5 and 2.3 μg m^-3, respectively for winter season. Summer mean OC and EC levels at the suburban site were 5.46 and 0.37 μg m^-3, respectively, while those for winter were found as 6.68 and 0.61 μg m^-3.The contributions of OC and EC to measured PM₁₀ levels were found in the range of 10% to 60% and 1% to 7%, respectively, at the urban station while the associated contributions were in the range of 10% to 50% and 0.6% to 6%, respectively, at the suburban station. The concentrations measured during winter months in both areas were found to be higher than those measured during summer months. The EC tracer method was used in order to estimate the SOC contribution. The contribution of SOC concentrations to the total PM₁₀ mass was found to be higher during winter in the urban area and during summer in the suburban area.

Activity of the soil enzymes and moss and lichen biomonitoring method used for the evaluation of soil and air pollution from tailing pond in Nižná Slaná (Slovakia)

The surrounding of the poorly maintained tailing ponds is endangered by the toxic substances and represents a serious risk for the health of the local population. The aim of the study was to determine the soil pollution by the hazardous elements (As, Cr, Cd, Cu, Fe, Mn, Ni, Pb, Zn) around the tailing pond using contamination factor (C_f), degree of contamination (C_d) and pollution load index (PLI). The health and the condition of soil were evaluated by soil enzyme activity (urease, acid and alkaline phosphatase, florescein diacetate, and ß-glucosidase). The spreading of the airborne hazardous elements from the body of the tailing pond was evaluated by moss and lichen bag technique and relative accumulation factor was used for the result expression. Cd, Fe, and Mn in soils reached above the limit values at all sampling sites. According to the degree of contamination (C_d), the soils at the sampling area were very high contaminated by As, Cd, Cu, Fe, Mn, Ni, and Pb. The most part of the assessed area was according to the PLI values extremely polluted. The air pollution was the most serious around the tailing pond, but serious levels of some hazardous elements were determined also in the remote distances.