Sulfate-reducing bacteria unearthed: ecological functions of the diverse prokaryotic group in terrestrial environments.

Sulfate-reducing prokaryotes (SRPs) are essential microorganisms that play crucial roles in various ecological processes. Even though SRPs have been studied for over a century, there are still gaps in our understanding of their biology. In the past two decades, a significant amount of data on SRP ecology has been accumulated. This review aims to consolidate that information, focusing on SRPs in soils, their relation to the rare biosphere, uncultured sulfate reducers, and their interactions with other organisms in terrestrial ecosystems. SRPs in soils form part of the rare biosphere and contribute to various processes as a low-density population. The data reveal a diverse range of sulfate-reducing taxa intricately involved in terrestrial carbon and sulfur cycles. While some taxa like Desulfitobacterium and Desulfosporosinus are well studied, others are more enigmatic. For example, members of the Acidobacteriota phylum appear to hold significant importance for the terrestrial sulfur cycle. Many aspects of SRP ecology remain mysterious, including sulfate reduction in different bacterial phyla, interactions with bacteria and fungi in soils, and the existence of soil sulfate-reducing archaea. Utilizing metagenomic, metatranscriptomic, and culture-dependent approaches will help uncover the diversity, functional potential, and adaptations of SRPs in the global environment.

Diatom cell-size composition as a novel tool for quantitative estimates of the water table in peatlands.

Diatom cell-size composition is an indicator of aquatic environmental changes but has been rarely investigated, especially in semi-terrestrial peatlands. In this study, both taxonomic composition and cell-size composition of diatoms were analysed in 41 samples from two montane peatlands, northeastern China. Redundancy analyses revealed that diatom taxonomic composition was significantly related to the depth to the water table (DWT) and Ca2+, while cell-size composition was significantly associated with DWT and Si. DWT was the most important factor and its sole effect explained 26.2% and 17.9% of the total variance in taxonomic composition and cell-size composition, respectively. Accordingly, diatom-based water-table transfer functions were developed based on taxonomic composition and cell-size composition, respectively. The maximum-likelihood (ML) model based on diatom taxonomic composition had the best performance, with a correlation coefficient value (R2) of 0.78 and the root mean squared error of prediction (RMSEP) of 6.66 cm. The ML model based on cell-size composition had similar performance, with an R2 of 0.78 and the RMSEP of 6.87 cm, suggesting that diatom cell-size composition can be a new quantitative means to track past water-table changes. This method requires further appraisal with palaeoecological data but offers a new option that deserves exploration.

Microplastics in the environment: analytical chemistry methods, sorption materials, risks and sustainable solutions.

This Feature Article reports general and more specific aspects about microplastic (MP) contamination in continental and marine waters as well as in terrestrial environment. It describes a critical vision of the analytical methods commonly used for MP characterization and determination, including recommendations on green analytical chemistry (GAC) protocols. Insights into MPs as sorption materials and carriers for a variety of emerging contaminants like pharmaceuticals and pesticides are highlighted. Risks to biota living in aquatic and terrestrial environments and human-health-related effects with specific examples of surface and groundwater used for drinking water sources near contaminated sites like landfills are summarized. Lastly, sustainable solutions for how to improve the analysis and comparison of MP detection at the global level is given, including the need for standardized analytical protocols as well as the performance of additional interlaboratory exercises. Additional recommendations include a global database on MP levels made available to all authors to better compare their data qualitatively with that previously published. Policy and remediation actions on how to reduce and mitigate MP pollution may include different types of actions like an improved waste management and reuse system, the development of bioplastics and new plastic materials, as well as legally binding additional funding to cope with increasing plastic pollution at the global scale.

Toxicokinetics and Particle Number-Based Trophic Transfer of a Metallic Nanoparticle Mixture in a Terrestrial Food Chain.

Herein, we investigated to which extent metallic nanoparticles (MNPs) affect the trophic transfer of other coexisting MNPs from lettuce to terrestrial snails and the associated tissue-specific distribution using toxicokinetic (TK) modeling and single-particle inductively coupled plasma mass spectrometry. During a period of 22 days, snails were fed with lettuce leaves that were root exposed to AgNO3 (0.05 mg/L), AgNPs (0.75 mg/L), TiO2NPs (200 mg/L), and a mixture of AgNPs and TiO2NPs (equivalent doses as for single NPs). The uptake rate constants (ku) were 0.08 and 0.11 kg leaves/kg snail/d for Ag and 1.63 and 1.79 kg leaves/kg snail/d for Ti in snails fed with NPs single- and mixture-exposed lettuce, respectively. The elimination rate constants (ke) of Ag in snails exposed to single AgNPs and mixed AgNPs were comparable to the corresponding ku, while the ke for Ti were lower than the corresponding ku. As a result, single TiO2NP treatments as well as exposure to mixtures containing TiO2NPs induced significant biomagnification from lettuce to snails with kinetic trophic transfer factors (TTFk) of 7.99 and 6.46. The TTFk of Ag in the single AgNPs treatment (1.15 kg leaves/kg snail) was significantly greater than the TTFk in the mixture treatment (0.85 kg leaves/kg snail), while the fraction of Ag remaining in the body of snails after AgNPs exposure (36%) was lower than the Ag fraction remaining after mixture exposure (50%). These results indicated that the presence of TiO2NPs inhibited the trophic transfer of AgNPs from lettuce to snails but enhanced the retention of AgNPs in snails. Biomagnification of AgNPs from lettuce to snails was observed in an AgNPs single treatment using AgNPs number as the dose metric, which was reflected by the particle number-based TTFs of AgNPs in snails (1.67, i.e., higher than 1). The size distribution of AgNPs was shifted across the lettuce-snail food chain. By making use of particle-specific measurements and fitting TK processes, this research provides important implications for potential risks associated with the trophic transfer of MNP mixtures.

Temporal trends in PFAS concentrations in livers of a terrestrial raptor (common buzzard; Buteo buteo) collected in Belgium during the period 2000-2005 and in 2021.

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic chemicals that have been globally distributed. Biological time series data suggest variation in temporal PFAS concentrations due to regulations and the phase-out of multiple PFAS analytes. Nonetheless, biomonitoring temporal trends of PFAS concentrations in raptors has only been done sporadically in Europe at a national scale. In the present study, we examined the concentrations of 28 PFAS in livers of common buzzard (Buteo buteo) collected in Belgium in the period 2000-2005 and in 2021. Despite the regulations and phase-out, the ΣPFAS concentrations remained similar in the livers over the past 20 years. However, over time the abundance of perfluorooctane sulfonate (PFOS), dominant in livers collected in 2000-2005, to the ΣPFAS concentration decreased from 46% to 27%, whereas the abundance of perfluorotetradecanoic acid (PFTeDA), dominant in 2021, increased from 19% to 43%. The PFOS concentrations in the present study did not exceed the Toxicity Reference Values (TRVs), which were determined in liver on the characteristics of an avian top predator. The absence of temporal changes in PFAS concentrations is hypothesized to be due to a lagged response in environmental concentrations compared to atmospheric concentrations.

Enhanced Transport of TiO2 in Unsaturated Sand and Soil after Release from Biodegradable Plastic during Composting.

Biodegradable plastics can reach full degradation when disposed of appropriately and thus alleviate plastic pollution caused by conventional plastics. However, additives can be released into the environment during degradation and the fate of these additives can be affected by the degradation process. Here, we characterized TiO2 particles released from a biodegradable plastic mulch during composting and studied the transport of the mulch-released TiO2 particles in inert sand and agricultural soil columns under unsaturated flow conditions. TiO2 particles (238 nm major axis and 154 nm minor axis) were released from the biodegradable plastic mulch in both single-particle and cluster forms. The mulch-released TiO2 particles were fully retained in unsaturated soil columns due to attachment onto the solid-water interface and straining. However, in unsaturated sand columns, the mulch-released TiO2 particles were highly mobile. A comparison with the pristine TiO2 revealed that the mobility of the mulch-released TiO2 particles was enhanced by humic acid present in the compost residues, which blocked attachment sites and imposed steric repulsion. This study demonstrates that TiO2 particles can be released during composting of biodegradable plastics and the transport potential of the plastic-released TiO2 particles in the terrestrial environment can be enhanced by compost residues.

Macroplastic accumulation in roadside ditches of New York State's Finger Lakes region (USA) across land uses and the COVID-19 pandemic.

Macroplastics are a ubiquitous and growing environmental contaminant with impacts in both marine and terrestrial systems. Marine sampling has dominated research in this field, despite the terrestrial origins of most plastic debris. Due to the high surface water connectivity facilitated by roadside ditches, these landscape features provide a unique sampling location linking terrestrial and surface water systems. We collected and analyzed macroplastic accumulation by number of pieces, mass, and polymer type in roadside ditches across four land uses, before and during the COVID-19 pandemic in the Finger Lakes Region of New York State. Commercial land use plastic accumulation rate was highest, while forested land use accumulation rates were lowest on a piece basis. Pre-COVID-19 piece accumulation rates were significantly higher than COVID-19 piece accumulation rates across all land uses. Mass accumulation rates followed similar patterns observed in piece accumulation, but the patterns were not always statistically significant. Plastic type 4 (i.e. thin plastic films), especially plastic bags and wrappers, was the most frequently collected type of macroplastic by piece across all land uses within the 1-7 Resin Identification Codes. By mass, the data were distributed less consistently across land uses. Cigarette filters, containing the polymer cellulose acetate, were the most frequently found roadside plastic, but are not within the 1-7 classification system. Our results suggest that policies in place limiting plastic bag usage could substantially reduce roadside plastics but other plastics, such as food wrappers and other single use plastic films, which comprised a large proportion of the plastic debris collected, should also be regulated to further decrease macroplastic pollution.

Leaf color is fine-tuned on the solar spectra to avoid strand direct solar radiation.

The spectral distributions of light absorption rates by intact leaves are notably different from the incident solar radiation spectra, for reasons that remain elusive. Incident global radiation comprises two main components; direct radiation from the direction of the sun, and diffuse radiation, which is sunlight scattered by molecules, aerosols and clouds. Both irradiance and photon flux density spectra differ between direct and diffuse radiation in their magnitude and profile. However, most research has assumed that the spectra of photosynthetically active radiation (PAR) can be averaged, without considering the radiation classes. We used paired spectroradiometers to sample direct and diffuse solar radiation, and obtained relationships between the PAR spectra and the absorption spectra of photosynthetic pigments and organs. As monomers in solvent, the spectral absorbance of Chl a decreased with the increased spectral irradiance (W m(-2) nm(-1)) of global PAR at noon (R(2) = 0.76), and was suitable to avoid strong spectral irradiance (λmax = 480 nm) rather than absorb photon flux density (µmol m(-2) s(-1) nm(-1)) efficiently. The spectral absorption of photosystems and the intact thallus and leaves decreased linearly with the increased spectral irradiance of direct PAR at noon (I dir-max), where the wavelength was within the 450-650 nm range (R(2) = 0.81). The higher-order structure of photosystems systematically avoided the strong spectral irradiance of I dir-max. However, when whole leaves were considered, leaf anatomical structure and light scattering in leaf tissues made the leaves grey bodies for PAR and enabled high PAR use efficiency. Terrestrial green plants are fine-tuned to spectral dynamics of incident solar radiation and PAR absorption is increased in various structural hierarchies.

Temporal and spatial variations of radioactive cesium levels in Northeast Japan following the Fukushima nuclear accident.

Radioactive emissions into the environment from the Fukushima Daiichi Nuclear Power Plant accident led to global contamination. Radionuclides such as 131I, 134Cs, and 137Cs were further transported to North America and Europe. Thus, the Fukushima Daiichi Nuclear Power Plant accident is a global concern for both human health and the ecosystem because a number of countries ban or impose restrictions the import of Japanese products. In the present study, three-year (May 2011 to May 2014) fluctuations and accumulations of Cs, 134Cs, and 137Cs in two salmonid fish, white-spotted char and masu salmon were examined in Northeast Japan. The total Cs, 134Cs, and 137Cs levels in the fish gradually decreased throughout the three-year studied period after the Fukushima Daiichi Nuclear Power Plant accident; however, higher levels (more than 100 Bq kg-1) were still detected in the Fukushima prefecture and neighboring prefectures in Japan 3 years after the Fukushima Daiichi Nuclear Power Plant accident. Spatial radiocesium levels gradually decreased with increasing distance from the Fukushima Daiichi Nuclear Power Plant (Fukushima prefecture). The radiocesium levels facing the Pacific Ocean area were generally higher than those facing the Sea of Japan area. These results suggest that radionuclides from Fukushima Daiichi Nuclear Power Plant are still widely distributed and remain in the natural environment in Northeast Japan.

Existence and fate of microplastics in terrestrial environment: A global fretfulness and abatement strategies.

Widespread use of plastics in consumer products, packaging, cosmetics, and industrial and agricultural production has resulted in the ubiquitous occurrence of microplastics in terrestrial environment. Compared to the marine environment, only limited studies have investigated the microplastics pollution and associated risk in terrestrial environment. The present review summarizes the global distribution of microplastics in terrestrial environment, their transport pathways and fate, risk to ecosystem and human health, and abatement strategies. Small particle sizes (<500 µm); fragment, fiber, and film shapes; transparent and white color; polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) polymers were the major characteristics of the microplastics found in terrestrial environment. Microplastics in soils negatively affect soil organisms, while the impact of microplastics in terrestrial environment on human health is poorly understood, which needs to be explored further as there is clear evidence on their presence in human bodies. The removal of microplastics from soil environment is quite complex and costly, thus prevention of their releases is preferable. Among the existing abatement options, biodegradation, which harnesses bacterial strains to degrade microplastics through enzymatic hydrolysis, hold promise for terrestrial environment. Strengthening global cooperation, implementing timely policies on plastic use and recycle, and developing new technologies for control of microplastics are recommended to reduce the pollution in terrestrial environment. Global effort on reducing plastic wastes and enhancing their management is imperative, while substitution with biodegradable plastics could help minimize future accumulation of microplastics in terrestrial environment.

Microplastics in Ecuador: A review of environmental and health-risk assessment challenges.

Pollution from plastic debris and microplastics (MPs) is a worldwide issue. Classified as emerging contaminants, MPs have become widespread and have been found not only in terrestrial and aquatic ecosystems but also within the food chain, which affects both the environment and human health. Since the outbreak of COVID-19, the consumption of single-use plastics has drastically increased, intensifying mismanaged plastic waste in countries such as Ecuador. Therefore, the aim of this review is to 1) summarize the state of MP-related knowledge, focusing on studies conducted with environmental matrices, biota, and food, and 2) analyze the efforts by different national authorities and entities in Ecuador to control MP contamination. Results showed a limited number of studies have been done in Ecuador, which have mainly focused on the surface water of coastal areas, followed by studies on sediment and food. MPs were identified in all samples, indicating the lack of wastewater management policies, deficient management of solid wastes, and the contribution of anthropogenic activities such as artisanal fishing and aquaculture to water ecosystem pollution, which affects food webs. Moreover, studies have shown that food contamination can occur through atmospheric deposition of MPs; however, ingredients and inputs from food production, processing, and packaging, as well as food containers, contribute to MP occurrence in food. Further research is needed to develop more sensitive, precise, and reliable detection methods and assess MPs' impact on terrestrial and aquatic ecosystems, biota, and human health. In Ecuador specifically, implementing wastewater treatment plants in major cities, continuously monitoring MP coastal contamination, and establishing environmental and food safety regulations are crucial. Additionally, national authorities need to develop programs to raise public awareness of plastic use and its environmental effects, as well as MP exposure's effects on human health.

Pesticides in the population of European hedgehogs (Erinaceus europaeus) in Denmark.

European hedgehogs (Erinaceus europaeus) inhabit most of Denmark, except for a few smaller islands. Research from other European countries has shown that the hedgehog populations are in decline. The exposure to chemicals might contribute to this development, although their role is currently unknown. Our research studied the occurrence of 19 selected pesticides in the Danish hedgehog population as well as factors potentially explaining the levels of chemicals detected. We analysed 115 liver samples obtained from dead hedgehogs in 2016 for seven rodenticides, four insecticides and eight herbicides commonly used in Denmark at the time of sampling, applying a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method. Detection frequencies varied between 0.9% for fluroxypyr and trans-permethrin and 79% for bromadiolone. Rodenticides, insecticides and herbicides were detected in 84, 43, and 50% of the samples, respectively. The compounds most frequently detected included the insecticide imidacloprid (35%), the herbicide metamitron (29%) and the rodenticide bromadiolone (79%). Individual concentrations varied between non-detected to >2 µg/g. A total of 79% of the 115 hedgehogs contained more than one detectable pesticide, with up to nine of the 19 compounds detected in one individual. The detection frequencies were found to differ significantly between the Eastern and Western part of Denmark for difenacoum, difethialone and imidacloprid. However, no associations were found with sex, age, habitat type or the prevalence of mecC-MRSA and endoparasites in the hedgehogs tested. Whether or not the pesticide levels detected carry a health risk for the hedgehogs remains unknown as no adverse effect levels have yet been established for European hedgehogs for single compounds or pesticide mixtures.

New Insights into Nanoplastics Ecotoxicology: Effects of Long-Term Polystyrene Nanoparticles Exposure on Folsomia candida.

Despite the growing concern over nanoplastics' (NPls) environmental impacts, their long-term effects on terrestrial organisms remain poorly understood. The main aim of this study was to assess how NPls exposure impacts both the parental (F1) and subsequent generations (F2 and F3) of the soil-dwelling species Folsomia candida. After a standard exposure (28 days), we conducted a multigenerational study along three generations (84 days), applying polystyrene nanoparticles (PS NPs; diameter of 44 nm) as representatives of NPls. Endpoints from biochemical to individual levels were assessed. The standard test: PS NPs (0.015 to 900 mg/kg) had no effect in F. candida survival or reproduction. The multigenerational test: PS NPs (1.5 and 300 mg/kg) induced no effects on F. candida survival and reproduction along the three generations (F1 to F3). PS NPs induced no effects in catalase, glutathione reductase, glutathione S-transferases, and acetylcholinesterase activities for the juveniles of the F1 to F3. Oxidative damage through lipid peroxidation was detected in the offspring of F1 but not in the juveniles of F2 and F3. Our findings underscore the importance of evaluating multigenerational effects to gain comprehensive insights into the contaminants long-term impact, particularly when organisms are continuously exposed, as is the case with NPls.

Plastic pollution risks in bioretention systems: a case study.

We investigated plastic pollution in soil-based stormwater bioretention systems (BRS), which are potentially important pollutant receptors and pathways. Our integrated study is the first of its kind, focusing on plastic abundance, size fractionation, composition, and interactions with urban metrics (including housing density and auxiliary stormwater treatment infrastructure) in BRS filter media. Our results revealed that mesoplastic (MEP) and microplastic (MP) concentrations in BRS are comparable with those reported in other stormwater systems (e.g. wetlands) as well as soils in other land use areas (e.g. agriculture). Distributional sampling within the BRS revealed MP abundances do not change with horizontal distance from the inlet to the outlet. However, MEP abundances drastically decreased towards the outlet, indicating plastic accumulation within BRS. This is important because MEPs can breakdown into MPs which can affect BRS function as well as mobilise downstream. Yet our data uncovered more complex mechanisms involved in BRS plastic fate, with composition data revealing that MPs are not simply breakdown products of MEPs but are instead derived from different sources. Composition, morphology and colour analysis confirmed that BRS polymer liners are a key source of MPs and MEPs in soil filter media. Multivariate analysis of the data with urban design metrics showed gross pollutant traps are effective at decreasing MP concentrations in BRS but not as effective at controlling MEPs. Our results point to complex plastic transmission and accumulation pathways in BRS. Interception measures can partially alleviate plastic risk, but more work is needed to elucidate plastic long-term fate in BRS.

Soil to earthworm bioaccumulation of polyhalogenated carbazoles and related compounds: Lab and field tests.

Polyhalogenated carbazoles (PHCZs) are an emerging group of organic contaminants that have attracted attention because of their ubiquity, resistance to biodegradation, and toxicities. However, studies on the bioaccumulation of PHCZs in terrestrial organisms are limited. In the present study, bioaccumulation of 11 PHCZs and two related compounds, carbazole (CZ) and benzocarbazole (BZCZ), from soil to earthworms was investigated by paired soil-earthworm samples from Hangzhou, China and a laboratory bioaccumulation test. The sum of the concentrations of the 11 polyhalogenated carbazoles (Σ11PHCZs), CZ and BZCZ in soils from Hangzhou were 1.78-67.27 ng/g dry weight, 1.11-57.90 ng/g dry weight, and 22.87-171.98 ng/g dry weight, respectively, while those in the earthworms were 179.49-892.90 ng/g lipid weight, 42.90-2140.42 ng/g lipid weight, and not detectable-2514.76 ng/g lipid weight, respectively. The average in situ biota-to-soil accumulation factors (BSAFs) ranged from 0.38 to 13.23, comparable to those in some reports for polychlorinated biphenyls and polybrominated diphenlethers. Site-independence of BSAFs and no correlation between log Cworm and log Csoil together support the hypothesis that distribution of PHCZs between soil and worms in Hangzhou didn't reach equilibrium. In the laboratory test, the accumulation trends of CZ, BZCZ, 3-bromocarbazole, 3,6-dichlorocarbazole, and 2,7-dibromocarbazole well fit to the first-order kinetics, with r2 ranging from 0.796 to 0.997. The BSAFs under two exposure concentration groups at steady-state conditions were 38.8-56.0 and 2.1-4.4, respectively, suggesting the capacity of bioaccumulation for these compounds. Enhancement of concentrations and resident time of the chemicals in soil would reduce the BSAF values, which may be related to the change of uptake process of the compound or redistribution of compound between soil and earthworm. A comparison of the theoretical steady-state concentrations with the nonlinear regression-based concentrations indicates that increasing the exposure time beyond 28 days is beneficial for studying the bioaccumulation of PHCZs.

Microbial community composition of terrestrial habitats in East Antarctica with a focus on microphototrophs.

The Antarctic terrestrial environment harbors a diverse community of microorganisms, which have adapted to the extreme conditions. The aim of this study was to describe the composition of microbial communities in a diverse range of terrestrial environments (various biocrusts and soils, sands from ephemeral wetlands, biofilms, endolithic and hypolithic communities) in East Antarctica using both molecular and morphological approaches. Amplicon sequencing of the 16S rRNA gene revealed the dominance of Chloroflexi, Cyanobacteria and Firmicutes, while sequencing of the 18S rRNA gene showed the prevalence of Alveolata, Chloroplastida, Metazoa, and Rhizaria. This study also provided a comprehensive assessment of the microphototrophic community revealing a diversity of cyanobacteria and eukaryotic microalgae in various Antarctic terrestrial samples. Filamentous cyanobacteria belonging to the orders Oscillatoriales and Pseudanabaenales dominated prokaryotic community, while members of Trebouxiophyceae were the most abundant representatives of eukaryotes. In addition, the co-occurrence analysis showed a prevalence of positive correlations with bacterial taxa frequently co-occurring together.

Variation in microplastic concentration, characteristics and distribution in sewage sludge & biosolids around the world.

Microplastics have been reported in wastewater treatment works across the world. The majority of microplastics are removed during the wastewater treatment process, with removal efficiencies between 57 % to 99 %. What happens to the microplastics removed from the wastewater, and how they accumulate in sewage sludge and biosolids (by-products of the wastewater treatment process), remains a topic of high interest. Here we systematically reviewed the current state of knowledge on the presence, concentration, and characteristics of microplastics in sewage sludge and biosolids globally to understand how biosolids may act as a pathway for microplastic pollution to soils. A systematic search was performed on the Web of Science and Science Direct databases. Sixty-five studies reporting on microplastic pollution in sewage sludge and biosolid products were identified, spanning twenty-five countries. Reported microplastic concentrations varied considerably from 0.193 microplastics/g to 1.69 × 105 microplastics/g with a median microplastic concentration of 22.41 microplastics/g, illustrating how many microplastics are captured during the wastewater treatment process, and retained in the sewage sludge. The extent to which biosolid recycling pollutes the terrestrial environment was compared between countries. High numbers of microplastics were estimated to reach fields via biosolid application with a wide variation of 8.2 × 1010 to 1.29 × 1015 microplastics/year between sixteen countries, although there was no significant difference in microplastic concentration between fields with a history of biosolid applications and control fields. The comparative risk this delivery of approx. 0.4 to 6430 tonnes of microplastics poses compared to the environmental benefits of nutrient and carbon recycling associated with biosolids reuse, or compared to other sources of microplastic pollution remains a global research imperative. The next step in scientific research needs to focus on solutions to the biosolid and circular economy conundrum - biosolids are a valuable source of nutrients but contain high concentrations of microplastics, which are ultimately entering the terrestrial environment.

Investigation of chemical partitioning of 7Be, 210Pb and 137Cs and novel dating of road sediment by 210Po:210Pb disequilibrium method.

A suite of road sediment and soil samples from a post-industrial city (Detroit, MI) were collected and analyzed for atmospherically-delivered 210Pb, 210Po, 7Be along with 226Ra and 137Cs in the bulk and size-fractionated solid samples. From the measured atmospheric depositional fluxes of 7Be, 210Po, and 210Pb, the initial 210Po/210Pb activity ratio was quantified. In all samples, there is disequilibrium between 210Po and 210Pb, with a 210Po/210Pb activity ratio (AR) of <1.0, which is reported for the first time. Using the measured 210Po/210Pb AR, the average 'apparent age' of road sediment was found to be 146 ± 62 days. Using numerical modeling, it is predicted that the (210Po/210Pb) excess activity ratio will reach a 'dynamic equilibrium' value of ~0.59 over a period of >1 year. Results from a subset of samples that were sequentially extracted for exchangeable, carbonate, Fe-Mn oxide, organic and residual phases indicate the Fe-Mn oxide fraction was found to contain the largest fraction of 7Be and 210Pb; however, the largest fraction of 210Pb was associated with the residual phase and is attributed to complexation of 210Pb with recalcitrant organic matter. This study shows that the natural tagging of 7Be and 210Po-210Pb pair via precipitation provides insights on the time scale of their mobility and adds a new dimension of time information on the pollutant-laden road sediment.

Investigation and analysis of microplastics in sewage sludge and biosolids: A case study from one wastewater treatment works in the UK.

There is an increasing concern about the impacts of microplastic pollution in the terrestrial environment. Identifying sources, pathways and sinks of terrestrial microplastics is crucial to determining environmental exposure and applying efficient intervention measures. In the UK alone, 3.5 million tonnes (wet weight) of biosolids from the wastewater industry are recycled each year to agricultural land, raising the possibility that recycling of biosolids could be a significant source of microplastic pollution to the terrestrial environment. To address this issue, the present study determined the presence of microplastics from across the whole sludge treatment stream from one exemplar wastewater treatment works in the UK. Both sewage sludge (a liquid by-product produced from the wastewater treatment processes) and biosolids (sewage sludge that has undergone a treatment process) were examined as a source of microplastics to the terrestrial environment. Microplastics were detected in all samples taken from across the treatment process with concentrations ranging from 37.7-286.5 number of microplastics/g of sludge (dry weight). The microplastic load in the final biosolid products produced at the site ranged from 37.7-97.2 number of microplastics/g of sludge (dry weight). The wastewater treatment works in this study produces 900 tonnes of anaerobically digested sludge cake and 690 tonnes of lime stabilised cake per month. Based on the results from this study, the application of these biosolids to agricultural land as fertilisers can potentially release 1.61 × 1010 and 1.02 × 1010 microplastics in anaerobically digested and lime stabilised sludge respectively, every month (equivalent to the same volume as >20,000 plastic bank cards). The results illustrate the extent to which microplastics may enter the terrestrial environment through this route.

Dynamics of airborne microplastics, appraisal and distributional behaviour in atmosphere; a review.

The use of plastics is common across all aspects of human life owing to its durable and versatile nature. The generation and utilization of plastics are directly related to the anthropogenic activities. The extensive use of plastics and adoption of inappropriate waste-management frameworks has resulted in their release into the environment, where they may persist. Different environmental factors, such as, photochemical, thermo-oxidation, and biological degradation, can lead to the degradation of plastics into micro- (MPs) and nano-plastics (NPs). The behaviour and concentration of MPs in the terrestrial environment can depend on their size, density, and local atmospheric conditions. Microplastics and nanoplastics may enter the food web, carrying various organic pollutants, which bio-accumulate at different trophic levels, prompting organism health concerns. Microplastics being airborne identifies as new exposure route. Dietary and airborne exposure to MPs has led researchers to stress the importance of evaluating their toxicological potential. The primary goal of this paper is to explore the environmental fate of MPs from sources to sink in the terrestrial environment, as well as detail their potential impacts on human health. Additionally, this review article focuses on the presence of airborne microplastics, detailed sample pre-processing methods, and outlines analytical methods for their characterization.