Determining of risk areas due to exposure to heavy metals in the Toluca Valley using epiphytic mosses as a biomonitor

Evaluation of an aquatic liverwort and terrestrial moss as biomonitors of heavy metals associated with particulate matter

In this study, the capacity of the aquatic liverwort Ricciocarpus natans L. and the terrestrial moss Entodon serrulatus Mitt. as biomonitors of heavy metals associated with particulate matter from a highly polluted urban area was evaluated, and concentrations in moss tissues were correlated with concentrations of PM10 and PM2.5 present in the atmosphere. The two species were exposed by the moss bag technique to the pollution of the Toluca Valley Metropolitan Area (TVMA) for two periods of 6 months, using the sites of the Automatic Atmospheric Monitoring Network of the Government of the State of Mexico, and were subsequently analyzed using elemental and structural characterization techniques. The results show that mainly the functional groups -OH and -NH, N-H and C-O on the surface of the liverwort and moss participate in the adsorption of heavy elements. The average enrichment factors of Cd and Pb show to be highly enriched (> 10) in the study area while chromium is not enriched (< 2). The statistical results indicate a temporary variation in the concentration of metals and particles in the atmosphere, where there is a lower concentration of these pollutants in the rainy and dry-cold season and a higher concentration in the dry-hot season and a possible association of Cr and Cd with PM10 and PM2.5. In addition, except for Cr, both species accumulate the metals associated with airborne particulate matter at equivalent levels. There is strong association between PM2.5 and PM10 particles and between the metals Cr-Pb-Fe in R. natans and between PM2.5-PM10 and Fe and between Cd-Cr-Pb in E. serrulatus and these pollutants are mainly associated with sampling sites with the highest concentrations of metals in the TVMA. Although terrestrial moss showed slightly better characteristics than aquatic liverwort as a biomonitor of heavy metals associated with atmospheric particles, these differences were not statistically significant for all metals, so both species could be useful for heavy metal biomonitoring in highly polluted urban areas.

Active Moss Biomonitoring of Mercury in the Mine-Polluted Area of Abbadia San Salvatore (Mt. Amiata, Central Italy)

Active biomonitoring of mercury (Hg) using non-indigenous moss bags was performed for the first time within and around the former Hg mining area of Abbadia San Salvatore (Mt. Amiata, central Italy). The purpose was to discern the Hg spatial distribution, identify the most polluted areas, and evaluate the impacts of dry and wet deposition on mosses. The exposed moss bags consisted of a mixture of Sphagnum fuscum and Sphagnum tenellum from an external uncontaminated area. In each site, two different types of moss bags, one uncovered (to account for the wet + dry deposition) and one covered (to evaluate the dry deposition), were exposed. The behavior of arsenic (As) and antimony (Sb) in the mosses was investigated to assess the potential relationship with Hg. GEM (Gaseous Elemental Mercury) concentrations were also measured at the same sites where the mosses were exposed, although only as a reference in the initial stages of biomonitoring. The results revealed that the main Hg emissions sources were associated with the former mining area of Abbadia San Salvatore, in agreement with the measured GEM concentrations, while arsenic and antimony were related to soil enriched in As-Sb waste material. The three elements registered higher concentrations in uncovered mosses with respect to the covered ones, i.e., wet deposition was the key factor for their accumulation on the uncovered mosses, while dry deposition was especially important for the covered samples in the mining area. Hg was accumulated in the mosses via GEM adsorption, uptake of particulate Hg, and precipitation via raindrops/snowfall, with almost no loss and without post-deposition volatilization. The results testified that the chosen biomonitoring technique was an extremely useful tool for understanding Hg transport and fate in a contaminated area.

Ecotoxicological assessments of atmospheric biomonitors exposed to urban pollution in a Brazilian metropolis

Subcellular metal distribution assessments are the most adequate biomonitoring approach to evaluate metal toxicity, instead of total metal assessments This study aimed to assess subcellular metal distributions and associations to the main metal exposure biomarker, metallothionein (MT), in two bromeliad species (Tillandsia usneoides and Tillandsia stricta) exposed established in industrial, urban, and port areas in the metropolitan region of Rio de Janeiro, southeastern Brazil, through an active biomonitoring approach conducted one year. Metals and metalloids in three subcellular fractions (insoluble, thermolabile and thermostable) obtained from the MT purification process were determined by inductively coupled plasma mass spectrometry (ICP-MS). Lower MT concentrations were observed both during the dry sampling periods, associated to the crassulacean acid metabolism (CAM) and during the COVID-19 pandemic, due to reduced urban mobility, decreasing pollutant emissions. The percentage of non-bioavailable metals detected in the insoluble fraction increased throughout the sampling period for both species. Several metals (Cr, Co, Cu, Cd, Mn, Ni, Se, and Zn), most associated with vehicle emissions, the main pollutant source in urban centers, were detected in the thermostable fraction and are, thus, associated with MT through the MT-metal detoxification route. Insoluble metal concentrations were higher in T. stricta, indicating that this species seems less susceptible to cellular metal exposure damage. A potential protective effect of Se and Fe was detected against Pb, suggested by a strong negative correlation, which may be attributed to antioxidant roles and similar uptake routes, respectively.

Evaluation of succulent plants Echeveria elegans as a biomonitor of heavy metals and radionuclides

This work evaluates the use of Echeveria elegans as a biomonitor of metals and radionuclides, using semi-urban soils as a study area. The study area is exposed to various trace elements of concern for various social groups in nearby localities. The quantification of metals and radionuclides was performed by X-ray fluorescence spectrometry and gamma spectrometry, respectively. Cumulative frequency distribution curves, descriptive statistics, and multivariate analysis were used to estimate the local geochemical baseline and identify geochemical and anthropogenic patterns of metals and radionuclides from topsoil and E. elegans. The evaluation of contaminants and the contribution of possible exposure routes (topsoil and atmospheric deposition) was performed with the enrichment factor (EF) and the relative concentration factor (CFR). The results suggest that the plant does not present significant physical stress due to the environmental conditions to which it was exposed. Likewise, it can bioaccumulate heavy metals from natural and anthropogenic sources. The quantification of radionuclides in the plant is below the detection limits, indicating a low bioavailability and transfer factor. The CFR and EF results showed that the plant accumulates metals from the topsoil and atmospheric deposition. The bioaccumulation mechanism would be related to the functioning of Crassulaceae Acid Metabolism (CAM). In topsoil, the organic acids of the plant would modify the solubility of the metals present in an insoluble form in the soil, acting as ligands and, subsequently, following the transport route of these metabolites. In atmospheric deposition, the metals deposited in the leaves would be incorporated into the plant through the opening of the stomata because of the capture of CO2 (at night, day, or during environmental stress) by the CAM. Overall, the evidence showed that the succulent can be used as a biomonitor of heavy metals. However, additional studies are required to determine its usefulness as a radionuclide biomonitor.

Moss as a passive biomonitoring tool for the atmospheric deposition and spatial distribution pattern of toxic metals in an industrial city

Anthropogenic pollution impacts human and environmental health, climate change, and air quality. Karabük, an industrial area from the Black Sea Region in northern Türkiye, is vulnerable to environmental pollution, particularly soil and air. In this research on methodological aspects, we analyzed the concentrations of six potential toxic metals in the atmospheric deposition of the city using the passive method of moss biomonitoring. The ground-growing terrestrial moss, Hypnum cupressiforme Hedw., was collected during the dry season of August 2023 at 20 urban points. The concentrations of Cr, Cu, Cd, Ni, Pb, and Co were determined in mosses by the ICP-MS method. Descriptive statistical analysis was employed to evaluate the status and variance in the spatial distribution of the studied metals, and multivariate analysis, Pearson correlation, and cluster analysis were used to investigate the associations of elements and discuss the most probable sources of these elements in the study area. Cd and Co showed positive and significant inter-element correlations (r > 0.938), representing an anthropogenic association mostly present in the air particles emitted from several metal plants. The results showed substantial impacts from local industry, manufactured activity, and soil dust emissions. Steel and iron smelter plants and cement factories are the biggest emitters of trace metals in the Karabük area and the primary sources of Cr, Cd, Ni, and Co deposition.

A comprehensive dataset of surface deformation satellite maps of the valley of Toluca, Mexico

This work presents a substantial compilation of ground deformation maps portraying the dynamic evolution of the Valley of Toluca (VT) in Mexico. The dataset comprises a repository of 1121 BEAM-DIMAP formated maps obtained by the Differential Interferometric Synthetic Aperture Radar (DInSAR) technique. Leveraging satellite image pairs from the Sentinel 1-A and Sentinel 1-B satellites, the dataset spans intervals of 1, 3, 6, and 12 months between each image acquisition and covers a panoramic timeframe from October 2014 to December 2022. This compilation provides an in-depth chronicle of the VT's ground transformations over a span of eight years that could be of interest to various disciplines. To enhance the dataset's robustness, a supplementary comma-separated values (CSV) dataset includes the coherence statistics from the satellite image pairs, substantiating the precision and dependability of the ground deformation maps presented herein.

Global ambient air quality monitoring: Can mosses help? A systematic meta-analysis of literature about passive moss biomonitoring

Surging incidents of air quality-related public health hazards, and environmental degradation, have prompted the global authorities to seek newer avenues of air quality monitoring, especially in developing economies, where the situation appears most alarming besides difficulties around 'adequate' deployment of air quality sensors. In the present narrative, we adopt a systematic review methodology (PRISMA, Preferred Reporting Items for Systematic reviews and Meta-Analyses) around recent global literature (2002-2022), around moss-based passive biomonitoring approaches which might offer the regulatory authorities a complementary means to fill 'gaps' in existing air quality records. Following the 4-phased search procedure under PRISMA, total of 123 documents were selected for review. A wealth of research demonstrates how passive biomonitoring, with strategic use of mosses, could become an invaluable regulatory (and research) tool to monitor atmospheric deposition patterns and help identifying the main drivers of air quality changes (e.g., anthropogenic and/or natural). Besides individual studies, we briefly reflect on the European Moss Survey, underway since 1990, which aptly showcases mosses as 'naturally occurring' sensors of ambient air quality for a slew of metals (heavy and trace) and persistent organic pollutants, and help assessing spatio-temporal changes therein. To that end, we urge the global research community to conduct targeted research around various pollutant uptake mechanisms by mosses (e.g., species-specific interactions, environmental conditions, land management practices). Of late, mosses have found various environmental applications as well, such as in epidemiological investigations, identification of pollutant sources and transport mechanisms, assessment of air quality in diverse and complex urban ecosystems, and even detecting short-term changes in ambient air quality (e.g., COVID-19 Lockdown), each being critical for the authorities to develop informed and strategic regulatory measures. To that end, we review current literature and highlight to the regulatory authorities how to extend moss-based observations, by integrating them with a wide range of ecological indicators to assess regional environmental vulnerability/risk due to degrading air quality. Overall, an underlying motive behind this narrative was to broaden the current regulatory outlook and purview, to bolster and diversify existing air quality monitoring initiatives, by coupling the moss-based outputs with the traditional, sensor-based datasets, and attain improved spatial representation. However, we also make a strong case of conducting more targeted research to fill in the 'gaps' in our current understanding of moss-based passive biomonitoring details, with increased case studies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10668-023-03043-0.

Establishing trace element concentrations for lichens and bryophytes in the ring of fire region of the Hudson Bay Lowlands, Ontario, Canada

Peatlands dominate the landscape of the Hudson Bay Lowlands in Ontario, Canada. Recently, mineral deposits of chromium (Cr), nickel (Ni), and copper (Cu) were discovered in the region and anticipated future industrial mining operations have the potential to impact the environment. Lichens and bryophytes are considered excellent biomonitors and indicators of deposition, deriving their nutrients directly from the atmosphere. Trace element concentrations in lichens and bryophytes have not been reported in the Hudson Bay Lowlands. Here, we seek to determine the baseline trace element concentrations of six non-vascular species (Evernia mesomorpha, Bryoria spp., Cladonia stellaris, Cladonia stygia, Sphagnum fuscum, and Sphagnum capillifolium) common to the region, explore linear relationships of trace elements with iron (Fe) as a signature of particulates with geogenic origin, and calculate trace element enrichment factors. Thalli, foliage, and peat (0-30 cm) were collected from 55 locations between 2013 and 2018 and analyzed for trace elements. Thalli and foliar concentrations are among the lowest reported in the broader literature and differ substantially from peat. Fe concentrations were significantly correlated (Pearson's r ≥ 0.8) with aluminum (Al), titanium (Ti), and vanadium (V) in all six species. Enrichment factors show some anthropogenic deposition effects non-vascular organism chemistry. Most trace element concentrations in lichens and bryophytes are indicative of long-range atmospheric transport of dust, but some is attributed to industry, with only minimal inclusions from the local area. Epiphytic lichens are well suited for ongoing atmospheric biomonitoring as industrialization commences.

Biomonitoring of metallic air pollutants in unique habitations of the Brahmaputra Valley using moss species-Atrichum angustatum: spatiotemporal deposition patterns and sources

In this paper, we have evaluated the bioaccumulation of metals by Atrichum angustatum, which is a readily available moss species in the Brahmaputra valley, India. A systematic investigation of metallic pollutants in the atmosphere was carried out using A. angustatum as a biomonitor collected from representative locations during three seasons viz. winter, pre-monsoon, and monsoon (n = 99) during the year 2018. The study was done in four unique habitations of the Brahmaputra Valley, which were further divided into three landuse areas: residential, roadside, and industrial. The highest accumulations were seen against Ca, Mg, Zn, and Fe. The calculated contaminant factors and ecological risk indices suggest that the Brahmaputra Valley is mostly contaminated by Cr, Zn, Cu, Ni, and Pb, and these metals pose a maximum ecological risk. The accumulation trend of metallic pollutants was site-specific, but most metals showed positive seasonal accumulation. A significant difference in spatial and seasonal accumulation patterns was specific to metal species. Principal component analysis (PCA) and inter-species correlations revealed that the air quality of Brahmaputra valley was greatly affected by coal burning, vehicular emission, biomass burning, road dust, and crustal dust. Finally, the study led us to the conclusion that A. angustatum can serve as a potential biomonitor for metallic pollutants.

Testing different methods of estimating edaphic inputs in moss biomonitoring

Although soil is known to contribute to the concentrations of elements in moss, protocols for atmospheric biomonitoring with terrestrial moss do not include recommendations on how to address this factor. As a result, researchers indiscriminately use a wide range of detection/correction methods without considering whether the results are equivalent. In this study, three of these methods were compared: i) use of the enrichment factor (EF) index; ii) calculation of the ratios of different elements in soil and moss, and subtraction of the contribution of soil concentrations from the raw concentrations of elements in mosses (SCS); and iii) positive matrix factorization (PMF), a receptor modelling method for source apportioning based on multivariate analysis techniques. The aim of the comparison was to determine whether the methods produce equivalent results and, if not, which method is the most appropriate for use in moss biomonitoring surveys. The data used corresponded to 146 samples of Pseudoscleropodium purum collected from a regular sampling grid of 15 × 15 km in Galicia (NW Spain). Comparison of the methods revealed that, although they yield relatively similar results, the corresponding interpretations are not equivalent and none of the methods provides a reliable estimate of the soil contribution to the concentrations of elements in moss samples. Independently of the technique applied, use of Ti as a reference element is not recommended, because, at least in this study, it was present at unusually high levels in moss. Given the absence of a reliable correction method and the fact that most elements are present in fairly high amounts in the soil, we recommend using atmospheric biomonitoring with moss only for Cu, Zn and Cd, i.e. for those elements in moss for which the soil contributes very low amounts and corrections are not therefore necessary.

Atmospheric Metal Biomonitoring Along a Highway Near Atlantic Rainforest Environmental Protection Areas in Southeastern Brazil

Vehicles are quite possibly the main sources of particulate matter, and their emissions can cause damage to surrounding ecosystems. Traditional atmospheric monitoring, however, is expensive. Therefore, airborne biomonitoring is an alternative method that allows for air quality assessment. In this study, we evaluated air quality at a federal highway (BR-040) close to Atlantic Rainforest remnants by quantifying metals in biomonitor tissues by ICP-MS. Tillandsia usneoides and Tillandsia stricta plants were relocated to the investigation zone and collected after five months of exposure. Metal concentration profiles were evaluated using statistical analyses, namely exposure-to-reference (ER) ratios and enrichment factors (EF). Results indicate that V, Cr, Fe, Cu, Zn and Sn enrichment were observed in all study sites. The EF for Cr, Mn, Pb, Ni, Co, Cu, Zn, Cd, and Sn ranged from high to very high, indicating anthropogenic sources. Both species were effective atmospheric biomonitors, proving to be an important tool, mainly in areas where conventional monitoring is not possible.

Source and spatial distribution of airborne heavy metal deposition studied using mosses as biomonitors in Yancheng, China

Naturally growing mosses have been successfully used as biomonitors of atmospheric heavy metal (HM) deposition. In recent years, with rapid economic development, environmental pollution in Yancheng, a coastal city in central Jiangsu Province, China, has become increasingly serious. However, to date, there have been no reports on atmospheric HM deposition in Yancheng. In this study, we investigated the HM concentrations and Pb isotopes in the moss Haplocladium microphyllum (Hedw.) Broth. from Yancheng and analyzed their main sources. The concentrations of HM in mosses from Yancheng were higher than those recorded in other studies of mosses from HM smelting regions and pollution-free areas of Eurasia and Alaska. The contamination factor value suggested that the pollution level of Cd was the highest. The pollution load index indicated that the studied area was severely contaminated with Cd, Cr, Pb, Zn, V, Ni, and Cu. Positive matrix factorization was employed to identify the contamination sources of HM and apportion their source contributions in mosses. The contributions of the natural source, together with manufacturing and construction, metal processing and chemical industries, traffic emissions and fuel burning in industrial activities, and agricultural activities, accounted for 53%, 33%, 12%, and 2%, respectively. The Pb isotopic ratios in the mosses (1.125-1.164 for 206Pb/207Pb, 2.059-2.148 for 208Pb/206Pb) further proved that metal processing and traffic emissions were the main sources of Pb contamination. These results are useful for developing various effective measures to prevent and reduce atmospheric HM deposition in Yancheng.

Assessment of metals in PM10 filters and Araucaria heterophylla needles in two areas of Quito, Ecuador

The reliability of Araucaria heterophylla needles as a biomonitor was evaluated by analyzing the concentration of metals in PM₁₀ filters and in Araucaria heterophylla needles. The sampling campaign was carried out at two sites in the city of Quito, Ecuador, in 2017–2019. Concentrations of Cr, Cu, K, Mn, Pb, Zn, Ca, Fe, Al and Mg were determined in PM₁₀ filters and in Araucaria heterophylla needles using an Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES). The annual mean concentrations of PM₁₀ ranged between 24.9 and 26.3 μg m⁻³, exceeding the limit established by the World Health Organization (20 μg m⁻³). Statistical analyses, performed for the PM₁₀ filters, showed that dust resuspension and anthropogenic activities were important sources for PM₁₀ emissions in the city. Metals related to natural emissions (Ca, Mg, K, Al and Fe) dominated in both types of samples, while the minor metals were those related to anthropogenic emissions (Zn, Cu, Cr and Pb). The former were positively associated with the needle samples, while the latter were associated with PM₁₀ filters. This work not only improved scientific knowledge on the concentrations of PM₁₀ and metals in the Andean city of Quito, but also greatly contributed to the progress of research on the use of Araucaria heterophylla needles as a biomonitor.

A Soft-Path Solution to Risk Reduction by Modeling Medical Waste Disposal Center Location-Allocation Optimization

The risk of medical waste pollution and huge demand of daily medical waste disposal pose great difficulties to medical waste management. Establishing medical waste disposal centers (MWDCs) is considered one of the ways to reduce the environmental and public risk of medical waste pollution. However, how to serve the medical waste disposal demand in optimal MWDCs' locations is a key challenge due to the complexity of the whole system and relationships among stakeholders. This article develops a soft-path solution for reducing risks as well as mitigating the related costs by optimizing the MWDC location-allocation problem. A risk mitigation-oriented bilevel equilibrium optimization model is developed for modeling the Stackelberg game behavior between the local government and the medical institutions. The objectives of the local government are minimizing the total risk of loss, the subsidy costs, and the investment cost of building the MWDCs, while minimizing the disposal and transportation costs are the objectives at the medical institution level. Fuzzy random variables are introduced by combining insufficient historical data with expert knowledge via consulting surveys to describe the coexisting uncertainties in the data. To solve the model, a hybrid approach combined with the interactive fuzzy programming technique and an Entropy-Boltzmann selection-based genetic algorithm are designed and tested. The Chengdu Medical Waste Disposal Centers Planning Project is used as a practical application. The results show that it is possible to achieve a balanced market with higher economic efficiency and significantly reduced risk through an appropriate principle of interactive actions between the bilevel stakeholders.