(Persistent) Organic pollutants in Germany: results from a pilot study within the 2015 moss survey

Organophosphate esters in terrestrial environments of Fildes Peninsula, Antarctica: Occurrence, potential sources, and bioaccumulation

Despite growing concerns regarding the long-range transport (LRT) and ecological risks of organophosphate esters (OPEs), information on the environmental behaviors of OPEs in polar terrestrial ecosystems remains inadequate. In the present study, 10 OPEs were analyzed in soil and vegetation samples collected from Fildes Peninsula, Antarctica. The OPE concentrations in Antarctic soils, mosses, and lichens ranged from 0.87 to 15.7 ng/g dry weight (dw), 9.8 to 113 ng/g dw, and 3.6 to 75.2 ng/g dw, respectively. Non-chlorinated OPEs predominated in terrestrial matrices, accounting for approximately 76 % of the OPE composition. Source identification indicated that OPE contamination in Antarctica likely resulted from local anthropogenic sources and LRT. Moreover, the bioaccumulation behavior of OPEs from soil to vegetation was assessed using bioconcentration factors (BCFs), revealing a significant non-linear trend of initial increase and subsequent decrease in BCFs relative to the lipophilicities of the octanol-air partition coefficient (log KOA) and octanol-water partition coefficient (log KOW). While low levels of OPEs in Antarctic terrestrial environments were reported in this study, their sustained inputs and potential ecological risks in polar regions warrant further attention.

Moss biomass as effective biosorbents for heavy metals in contaminated water

The study explored batch adsorption of Cd(II) and Pb(II) ions using moss biomass from Barbula consanguinea and Hyophila involuta, assessing removal efficiency concerning various parameters. Both moss species showed high removal rates for Cd(II) (87 % for B. consanguinea and 89 % for H. involuta) and Pb(II) (93 % for B. consanguinea and 94 % for H. involuta) from contaminated water, reaching equilibrium within 30 min. While Cd(II) removal was pH-independent, Pb(II) removal showed pH-dependence, peaking at pH 5.0-5.5. Adsorption isotherm analysis indicated that the Langmuir, Freundlich, Elovich, Sips, and Redlich-Peterson models best described Cd(II) and Pb(II) adsorption onto both moss species (except for Cd(II) adsorption onto H. involuta), with R 2  > 0.98. This confirms a heterogeneous surface with both monolayer and multilayer adsorption sites. The pseudo-second-order kinetic model confirmed chemisorption on moss biomass from both species. FTIR spectra identified major binding sites such as phenols, alkaloids, amines, alkenes, nitro compounds, and low-molecular-weight carbohydrates. EDS analysis validated the bonding of Cd(II) and Pb(II) ions to the biomass surface by displacing Ca(II) ions. According to the Langmuir model, moss biomass exhibited selective adsorption, favoring Pb(II) over Cd(II). B. consanguinea showed a higher adsorption capacity than H. involuta, which is attributed to its higher negative zeta potential. This study underscores the novelty of moss biomass for heavy metal removal in wastewater treatment, highlighting its sustainability, effectiveness, cost-efficiency, versatility, and eco-friendliness.

Bacterial response to the combined pollution of benzo[a]pyrene and decabromodiphenyl ether in soil under flooding anaerobic condition

This study investigated the interaction between the co-pollutants of Benzo[a]pyrene (BaP) and decabromodiphenyl ether (BDE-209) and the bacterial community in soil under flooding anaerobic condition. Three levels of combined pollution (at nominal concentrations of 1, 5, and 25 mg/kg, respectively, for each pollutant), their corresponding sterilized controls, and a blank control (CK) were set up. During the incubation time of 270 days, BaP attenuated more easily than BDE-209. The second-order rate constant of BaP attenuation was negatively correlated with the Ln value of initial BaP concentration. Maximal difference in bacterial community occurred between the CK soil and the highly polluted soil. Desulfomonilaceae, Parcubacteria and Rhodanobacter were probably involved in BaP and BDE-209 degradation, while Nitrosomonadaceae, Phenylobacterium and Mitochondria were significantly suppressed by BaP and BDE-209 or their degrading products. Genes narI, bcrC, fadJ, had, dmpC, narG and CfrA were involved in the degradation of BaP and BDE-209. Impacts of BaP and BDE-209 on metabolisms of carbon, nitrogen and sulfur were not significant. The results provide guidance for the management and remediation of the contaminated soil.

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.

The Application of Active Biomonitoring with the Use of Mosses to Identify Polycyclic Aromatic Hydrocarbons in an Atmospheric Aerosol

The use of biological indicators of environmental quality is an alternative method of monitoring ecosystem pollution. Various groups of contaminants, including organic ones, can be measured in environmental samples. Polycyclic aromatic hydrocarbons (PAHs) have not yet been determined by the moss bag technique. This technique uses several moss species simultaneously in urban areas to select the best biomonitoring of these compounds, which are dangerous to humans and the environment. In this research, a gas chromatography coupled with mass spectrometry was used for the determination of selected PAHs in three species of mosses: Pleurozium schreberi, Sphagnum fallax and Dicranum polysetum (active biomonitoring) and for comparison using an air filter reference method for atmospheric aerosol monitoring. The chlorophyll fluorescence of photosystem II (PSII) was also measured to assess changes in moss viability during the study. As a result of the study, the selective accumulation of selected PAHs by mosses was found, with Pleurozium schreberi being the best bioindicator—9 out of 13 PAHs compounds were determined in this species. The photosynthetic yield of photosystem (II) decreased by 81% during the exposure time. The relationship between PAHs concentrations in mosses and the total suspended particles (TSP) on the filter indicated the possibility of using this bioindicator to trace PAHs in urban areas and to apply the moss bag technique as a method supporting classical instrumental air monitoring.

Long-term trends of airborne halogenated flame retardants (HFRs) by means of tree leaf and shoot analyses

The historical air pollution with halogenated flame retardants (HFRs) in Germany was assessed by investigating tree leaf and shoot samples which have been archived in the German environmental specimen bank. Samples covered the period from 1985 to 2016. 43 HFRs comprising polybrominated diphenyl ethers as well as emerging brominated and chlorinated compounds such as Dechlorane Plus, DBDPE, or DPTE, were analysed in 115 samples from ten sub sites originating from six areas characterised by different land uses, including urban as well as a background site. HFRs were observed in each sample showing the widespread distribution of HFRs in Germany in tree leaves and shoots as bioindicators of past and present atmospheric pollution. Analytes observed at elevated concentrations were BDE 209, DBDPE and DPTE. Observed HFR-levels differed between analytes as well as sampling locations, particularly prior to the year 2000. They were typically highest at conurbation areas. Concentrations at the background site often belonged to the lowest ones observed, however, lowest values were not exclusively found there. The quantification frequencies appeared to decrease from the past to most recent samples. With few exceptions, atmospheric pollution of both, legacy and emerging HFRs, decreased significantly.

New classes of organic pollutants in the remote continental environment - Chlorinated and brominated polycyclic aromatic hydrocarbons on the Tibetan Plateau

Halogenated polycyclic aromatic hydrocarbons are carcinogenic and ubiquitous environmental organic pollutants. The abundance and sources of these compounds have not been studied in remote environments. We collected and analyzed air, soil, lichen, and moss samples from the Tibetan Plateau. Concentrations of chlorinated polycyclic aromatic hydrocarbons were 0.78-4.16 pg/m³ in air, 3.11-297 pg/g in soil, 260-741 pg/g in lichens, and 338-934 pg/g in mosses. Concentrations of brominated polycyclic aromatic hydrocarbons were 0.15-0.59 pg/m³ in air, 0.61-72.3 pg/g in soil, 33.5-64.9 pg/g in lichens, and 20.5-72.5 pg/g in mosses. The dominant congeners were 9- and 2-chlorophenanthrene, 1-chloropyrene, 3-chlorofluoranthene, and 1-bromopyrene. We found correlations between congener concentrations in lichens and in air, and lichens effectively predicted near-ground atmospheric concentrations of the pollutants. The enrichment of photochemically stable compounds in high-altitude environments is influenced by their physicochemical properties. Principal component analysis with multivariate linear regression of chlorinated polycyclic aromatic hydrocarbons measured in lichens provided an assessment of the relative source contributions, and suggested that in Medog County of Tibetan Plateau, 48% was likely from long-range combustion sources, 26% was from local burning sources, and 26% was from photochemical formation.

Enrichment effect of Hypnum plumaeforme on 210Po and 210Pb

The mosses have been widely used as bioindicators to investigate pollution and changes of heavy metals in different countries and regions. In this research, the field surveys were carried out for understanding the moss community and enrichment effects of the dominant species of mosses around the uranium mill tailings impoundment in South China, especially for the enriched contentions of ²¹⁰Pb and ²¹⁰Po in soil and Hypnum plumaeforme. The results showed that the maximum concentrations of U and ²²⁶Ra in the study sites were 93 mg kg^-1 and 1130.8 Bq kg^-1, respectively. The exhalation rate of ²²²Rn (ER_Rn), soil U, and ²²⁶Ra contents in SS₁, SS₂, and SS₃ were higher than CKS. With the increase of the distance from the central well, the contents of nuclides (U and ²²⁶Ra) in soils and H. plumaeforme were both decreased. And, the bioconcentration factors of H. plumaeforme for ²¹⁰Pb and ²¹⁰Po ranged from 1.05 to 1.49, and 1.25 to 1.40, respectively, indicating an accumulation of ²¹⁰Po and ²¹⁰Pb from soil by H. plumaeforme. These results indicated that H. plumaeforme is hopeful to become an accumulator plant for remediation of radon pollution, and also can be used as a potential indicator plant for radon pollution monitoring.

Modelling spatial patterns of correlations between concentrations of heavy metals in mosses and atmospheric deposition in 2010 across Europe

BACKGROUND

This paper aims to investigate the correlations between the concentrations of nine heavy metals in moss and atmospheric deposition within ecological land classes covering Europe. Additionally, it is examined to what extent the statistical relations are affected by the land use around the moss sampling sites. Based on moss data collected in 2010/2011 throughout Europe and data on total atmospheric deposition modelled by two chemical transport models (EMEP MSC-E, LOTOS-EUROS), correlation coefficients between concentrations of heavy metals in moss and in modelled atmospheric deposition were specified for spatial subsamples defined by ecological land classes of Europe (ELCE) as a spatial reference system. Linear discriminant analysis (LDA) and logistic regression (LR) were then used to separate moss sampling sites regarding their contribution to the strength of correlation considering the areal percentage of urban, agricultural and forestry land use around the sampling location. After verification LDA models by LR, LDA models were used to transform spatial information on the land use to maps of potential correlation levels, applicable for future network planning in the European Moss Survey.

RESULTS

Correlations between concentrations of heavy metals in moss and in modelled atmospheric deposition were found to be specific for elements and ELCE units. Land use around the sampling sites mainly influences the correlation level. Small radiuses around the sampling sites examined (5 km) are more relevant for Cd, Cu, Ni, and Zn, while the areal percentage of urban and agricultural land use within large radiuses (75-100 km) is more relevant for As, Cr, Hg, Pb, and V. Most valid LDA models pattern with error rates of < 40% were found for As, Cr, Cu, Hg, Pb, and V. Land use-dependent predictions of spatial patterns split up Europe into investigation areas revealing potentially high (= above-average) or low (= below-average) correlation coefficients.

CONCLUSIONS

LDA is an eligible method identifying and ranking boundary conditions of correlations between atmospheric deposition and respective concentrations of heavy metals in moss and related mapping considering the influence of the land use around moss sampling sites.