Biomonitoring of airborne microplastics and microrubbers in Shiraz, Iran, using lichens and moss.

HIGHLIGHTS: Microplastics (MPs) and microrubbers (MRs) determined in lichens and mosses around Shiraz. In lichens, MPs mainly thin fibres up to 1 MP g-1; MRs were < 0.1 MP g-1. In mosses, abundances were similar but with a greater fraction of larger, non-fibrous particles. Larger MPs and MRs decreased in abundance with distance and elevation from Shiraz. Around Shiraz, the common moss, Grimmia critina, would be the most suitable biomonitor. Lichens and mosses have been employed as biomonitors of atmospheric particulate pollutants, like metals and industrial solids, for many decades. Here, we evaluated the potential of nine species of crustose and foliose lichens and a widely distributed moss (Grimmia critina) to act as biomonitors of airborne microplastics (MPs) and microrubbers (MRs). About 200 lichens and 40 mosses were sampled across different altitudinal transects in the vicinity of Shiraz City, southwest Iran, and MPs and MRs were quantified and characterised after sample peroxidation. In most species of lichen, MP and MR abundance overall was < 1 g-1 and < 0.1 g-1, respectively, and the majority of plastics were fibres of < 10 µm in diameter and < 1000 µm in length. Respective weight normalised abundances of MPs and MRs were similar in G. critina, but there were greater proportions of both larger (> 1000 µm) and non-fibrous particles among the MPs. In both lichens and moss, there was a greater number of larger MPs and MRs at locations closest to and at the same elevation as Shiraz than at more distant and elevated locations, suggesting an inverse relationship between particle size and distance travelled. Among the lichens, members of the genus Acarospora, with their areolated form, appeared to act as the most suitable biomonitors for MPs and MRs. Overall, however, the wide distribution of the moss, G. crinita, and its ability to intercept and accumulate a broader range of sizes and shapes of MPs and MRs make this species a better choice, at least in the type of environment studied.

Biochar mitigates the postponed bioavailability and toxicity of phthalic acid esters in the soil.

Observed nowadays wide pollution of the environment with microplastic and phthalic acid esters (PAEs) (such as dimethyl phthalate, DMP; diethyl phthalate, DEP; dibutyl phthalate, DBP; benzyl butyl phthalate, BBP; di-(2-ethylhexyl) phthalate, DEHP and di-n-octyl phthalate, DNOP) is a result of their increased production and usage. Weak bonding with polymer matrix enables their easier mobilization in the environment and increased bioavailability. The aim of the presented studies was the estimation of the fate of six priority PAEs in the soil-vegetable system and the application of biochar to immobilize PAEs in the soil preventing their bioavailability to lettuce. Both the acute (one full lettuce development period) and prolongated effect (lettuce cultivated after 10 weeks from the first PAEs contamination) were estimated to examine the long-time exposure under crop rotation. The addition of 1 % of corn-derived biochar immobilized PAEs in the soil efficiently (up to 4 times increased concentration) with the following order: DBP < DEP < DMP < DEHP < DNOP < BBP. Bioavailable PAEs were determined in lettuce roots (DMP, BBP, DEHP), and lettuce leaves (DEP, DBP, DNOP) but the presence of biochar lowered their content. PAEs, although not available for lettuce, were available for other organisms, confirming that the bioavailability or lack of nutrients is of great importance in PAEs-polluted soil. In long-time experiments, without biochar amendment, all PAEs were 3-12 times more bioavailable and were mainly accumulated in lettuce roots. The biochar addition significantly reduces (1.5-11 times) PAEs bioavailability over time. However, the PAEs content in roots remained significantly higher in samples with crop rotation compared to samples where only lettuce was grown. The results confirmed that biochar addition to the soil reduces their bioavailability and mobility inside the plant, limiting their transport from roots to leaves and reducing the exposure risk but confirming that lettuce leaves may be a safe food when cultivated in PAEs-polluted soil.

Occurrence and dissipation mechanisms of organic contaminants during sewage sludge anaerobic digestion: A critical review.

Sewage sludge, a complex mixture of contaminants and pathogenic agents, necessitates treatment or stabilization like anaerobic digestion (AD) before safe disposal. AD-derived products (solid digestate and liquid fraction) can be used as fertilizers. During AD, biogas is also produced, and used for energy purposes. All these fractions can be contaminated with various compounds, whose amount depends on the feedstocks used in AD (and their mutual proportions). This paper reviews studies on the distribution of organic contaminants across AD fractions (solid digestate, liquid fraction, and biogas), delving into the mechanisms behind contaminant dissipation and proposing future research directions. AD proves to be a relatively effective method for removing polychlorinated biphenyls, polycyclic aromatic hydrocarbons, pharmaceuticals, antibiotic resistance genes and hydrocarbons. Contaminants are predominantly removed through biodegradation, but many compounds, especially hydrophobic (e.g. per- and polyfluoroalkyl substances), are also sorbed onto digestate particles. The process of sorption is suggested to reduce the bioavailability of contaminants. As a result of sorption, contaminants accumulate in the largest amount in the solid digestate, whereas in smaller amounts in the other AD products. Polar pharmaceuticals (e.g. metformin) are particularly leached, while volatile methylsiloxanes and polycyclic aromatic hydrocarbons, characterized by a high Henry's law constant, are volatilized into the biogas. The removal of compounds can be affected by AD operational parameters, the type of sludge, physicochemical properties of contaminants, and the sludge pretreatment used.

Dissolved organic matter influences the indigenous bacterial community and polycyclic aromatic hydrocarbons biodegradation in soils.

In polycyclic aromatic hydrocarbon (PAH) contaminated soils, bioremediation is superior to other strategies owing to its low cost and environmental friendliness. However, dissolved organic matter (DOM) and indigenous bacterial communities can affect the efficiency of PAH-degrading bacteria (PDB). This study found that exogenous PDB (C1) including the genera Acinetobacter, Stenotrophomonas, and Comamonas, decreased the bacterial diversity of Alfisol, Ultisol, Inceptisol, and Mollisol, and DOM enhanced the diffusion of PDB and the bioavailability of PAH. In addition, bacteria preferred to ingest low molecular weight DOM fractions, and the abundances of lipid-like and protein-like substances decreased by 0.12-3.03 % and 1.73-4.60 %. The DOM fractions had a more marked influence on the indigenous bacteria than the exogenous PDB, and PDB dominated the PAH biodegradation process in the soils. More COO functional groups promoted the utilization of higher molecular weight-related homologue fractions by bacteria, and lower molecular weight fractions carrying more CH2 functional groups declined during biodegradation. This study investigated the variations in bacterial communities during biodegradation and revealed the effects of DOM fractions on biodegradation in PAH-contaminated soils at the molecular level. These results will promote the development of bioremediation strategies for organics-contaminated soil and provide guidance for prediction models of soil biodegradation kinetics.

Exchangeable versus residual metals in naturally aged plastic litter.

Metals may be associated with plastics as additives arising from manufacture or through acquisition from the environment, but these associations are often poorly defined or referred to synonymously when considering metal availability. In this study, samples of plastic litter (n = 22) have been collected from various environmental and industrial compartments of Lublin Province, Poland, and fractionated according to polymer type (polyethylene, polyethylene terephthalate, nylon, expanded polystyrene, polypropylene, and "mixed") before being micronised to < 2 mm. Composites (n = 89) were subjected to two phases of a standardised and widely employed sequential extraction protocol (Bureau Communautaire de Reference; BCR) in order to define available (acid-soluble and exchangeable) and residual (soluble in boiling aqua regia) concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. For a given metal, total content, calculated by summing available and residual components, was highly variable, both between locations and amongst polymer categories, reflecting the heterogeneous distribution of a multitude of different additives. Overall, however, concentrations were greatest for Fe, with medians of several hundred to several thousand mg kg-1 amongst the different polymers, and lowest for Cd, Co, and Ni, where nearly all concentrations were below 10 mg kg-1. Median percentage metal availabilities were greatest for expanded polystyrene and were above 25% for Mn and Zn and below 10% for Cr and Fe in all polymer types. These observations are largely, but not entirely, attributed to the relative contributions of metals acquired from the environment and metals present as additives and residues. Significantly, the approach employed allows direct comparisons of metal availability in plastics with metal availability in environmental solids in order to evaluate the overall impacts of plastics in metal risk assessments.

Formation and biotoxicity of environmentally persistent free radicals in steelworks soil under thermal treatment.

Thermal treatment are commonly used to address organic contaminated soils. In particular, the pyrolysis of organic substances can result in the creation of environmentally persistent free radicals (EPFRs). We investigated a steelworks site in Chongqing (China) to observe changes in EPFRs before and after thermal treatment. Our findings revealed that the EPFRs were carbon-centered radicals with a g-factor < 2.0030 and a spin density ranging from n.d.-5.23 × 1015 spins/mg. The formation of EPFRs was driving by polycyclic aromatic hydrocarbons (PAHs), Mn, Cu, and total organic carbon (TOC). Following the thermal treatment, the spin densities of EPFRs increased by a factor of 0.25 to 1.81, with maximum levels reached at 300 °C. High molecular weight PAHs exhibited high heat capacity, enabling the generation of more EPFRs. The thermal decay of EPFRs occurred in two stages, with the shortest 1/e lifetime lasting up to 16.8 h. Raising the temperature or prolonging time can significantly reduce EPFRs levels. Thermal treatment increased the generation of EPFRs, hydroxyl radicals (•OH) and superoxide radical (•O2-), leading to a decrease in bacterial luminescence. Specifically, •OH contributed to approximately 73% of the B. brilliantus inhibition. Our results highlight that the thermal treatment significantly enhance EPFRs concentrations, and the treated soil remained ecologically risky. The knowledge of the formation of EPFRs and their biotoxicity is shedding new light on the thermal treatment risk management.

Increased concentration of PAH derivatives in biochar-amended soil observed in a long-term experiment.

During biochar preparation or application some toxic substances may be formed. The established limitations of the content of polycyclic aromatic hydrocarbons (PAHs) aim to monitor the fate of PAHs in the life cycle of biochar. The latest studies have revealed that besides PAHs, some of their derivatives with confirmed toxicity are formed. There has been no policy regards PAH derivatives in biochar yet. The aim of the presented studies was the estimation the changes in the content of PAHs and their derivatives during the agricultural application of biochar. A pot experiment with grass revealed that in a short time, both the content of PAHs and their derivatives was reduced. Similarly, when biochar was added to soil in a long-term experiment, the content of determined derivatives was below the limit of detection, whereas interestingly, the content of pristine PAHs increased with time. Co-addition of biochar and sewage sludge increased the content of PAHs and their derivatives indicating potential environmental hazard due to their presence. However, the key point is the estimation of the bioavailability of PAHs and their derivatives as only the bioavailable fraction is revealing the environmental hazard.

The high dose of biochar reduces polycyclic aromatic hydrocarbons losses during co-composting of sewage sludge and wheat straw.

The aim of the study was to investigate the effect of the biochar (BC) dose on solvent extractable (Ctot) and freely dissolved (Cfree) polycyclic aromatic hydrocarbons (PAHs) content during co-composting. A significantly better reduction of Σ16 Ctot PAHs after 98 days occurred during composting with BC (for 1% of BC - 44% and for 5% of BC - 23%) than in the control (15%). Despite the relatively high reduction of Ctot PAHs in the experiment with 5% BC rate, the content of the PAHs was still the highest compared to other variants. Regarding Cfree PAHs, 5% rate of BC resulted in the best reduction of PAHs, while the 1% BC dose resulted in a lower reduction of Cfree than the control. For 1% BC, PAHs losses was more effective, and sequestration processes played a less significant role than in the experiment with 5% dose of BC. The total and dissolved organic carbon, and ash were predominantly responsible for Ctot and Cfree losses, and additionally pH for Cfree. The results of the experiment indicate that BC performs a crucial role in composting, affecting the Ctot and Cfree PAHs in the compost but the final effect strictly depends on the BC dose.

Effect of chemical aging on phosphate adsorption and ecotoxicological properties of magnesium-modified biochar.

Using magnesium-biochar composites (Mg-BC) in adsorption allows for the efficient and economically relevant removal of phosphate (PO43-) from water and wastewater. Applying Mg-BC for pollutant removal requires evaluating the adsorption capacity of composites and their ecotoxicological properties. Investigating the composite aging during the application of these composites into the soil is also essential. In the present study, nonaged and aged (at 60 or 90 °C) Mg-BC composites were investigated in the context of pyrolysis temperature (500 or 700 °C). All analyzed biochars were examined by Fourier transform infrared spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and surface area. The content of polycyclic aromatic hydrocarbons (PAHs) (bioavailable Cfree and organic solvent-extractable Ctot), heavy metals (HMs), and environmentally persistent free radicals (EPFRs) were determined. Ecotoxicity was evaluated using tests with Folsomia candida and Allivibrio fischeri. The dependence of adsorption on pyrolysis temperature and composite aging time was observed. Changes in physicochemical properties occurring as a result of aging reduced the adsorption of PO43- on Mg-BC composites. It was found that nonaged Mg-BC700 was more effective (9.55 mg g -1) in the adsorption of PO43- than Mg-BC500 (5.75 mg g-1). The adsorption capacities of aged composites were from 21 to 61% lower than those of the nonaged composites. Due to aging, the content of Cfree PAHs increased by 3-5 times depending on the pyrolysis temperature. However, aging reduced the Ctot PAHs in all composites from 24 to 35% depending on the pyrolysis temperature. Ecotoxicological evaluation of Mg-BC composites showed increased toxicity after aging to both organisms. The use of aged BC potentially increases the contaminant content and toxicity of Mg-BC composites.

Effect of zinc-biochar composite aging on its physicochemical and ecotoxicological properties.

The stability of Zn-biochar composites is determined by environmental factors, including the aging processes. This paper focused on the ecotoxicological evaluation of Zn-biochar (Zn-BC) composites subjected to chemical aging. Pristine biochars and composites produced at 500 or 700 °C were incubated at 60 and 90 °C for six months. All biochars were characterized in terms of their physicochemical (elemental composition, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and porous structure), ecotoxicological properties (tested with Folsomia candida and Aliivibrio fischeri) and contaminant content (polycyclic aromatic hydrocarbons (PAH), heavy metals (HM) and environmentally persistent free radicals (EPFR)). An increase in the number of surface oxygen functional groups and increased hydrophilicity and polarity of all Zn-BC composites were observed due to oxidation during aging. It was also found that Zn-BC aging at 90 °C resulted in a 28-30% decrease in solvent-extractable PAHs (Æ©16 Ctot PAHs) compared to nonaged composites. The aging process at both temperatures also caused a 104 fold reduction in EPFRs in Zn-BC composites produced at 500 °C. The changes in the physicochemical properties of Zn-BC composites after chemical aging at 90 °C (such as pH and HM content) caused an increase in the toxicity of the composites to Folsomia candida (reproduction inhibition from 19 to 24%) and Aliivibrio fischeri (luminescence inhibition from 96 to 99%). The aging of composites for a long time may increase the adverse environmental impact of BC-Zn composites due to changes in physicochemical properties (itself and its interactions with pollutants) and the release of Zn from the composite.

Fast and reliable determination of phthalic acid esters in soil and lettuce samples based on QuEChERS GC-MS/MS.

Phthalates are commonly used as plasticizers, and solvents in industry and households. We propose an application of the QuEChERS method for the determination of six PAEs in the soil and lettuce (roots and leaves) by GC-MS/MS. The QuEChERS method validation procedure was performed and good linearity (>0.997), recovery (97.2-99.1 %), very low detection limits (0.09-0.43 ng/g), and satisfactory inter- and intraday precision (∼4%) were obtained confirming that QuEChERS GC-MS/MS applied for PAEs determination in the environmental samples is a cheap and environmentally friendly method. In general, the higher the number of carbon atoms in PAEs, the higher the percentage noted in the lettuce roots. At higher PAEs concentration (60 ng/g) the main bis(2-ethylhexyl) phthalate (DEHP) sink were roots whereas at lower concentrations (30 ng/g) most of DEHP was noted in lettuce leaves implying that the fate of PAEs was governed not by the chemical structure of PAEs but rather partitioning (logKow).

Extractability and phytotoxicity of heavy metals and essential elements from plastics in soil solutions and root exudates.

Plastic waste is increasing and is a serious environmental problem. Among the threats associated with plastics is the release of contaminants into the environment. This study aimed to evaluate the efficiency of metals release from plastics (low-density polyethylene (LDPE), polyethylene terephthalate (PET), and polypropylene (PP)) as affected by different soil solution types, artificial root exudates, and distilled water. The extent of metal release varied depending on the type of solution and plastic used. Metals were leached most effectively from plastics in soil solutions, followed by root exudates, and least effectively by distilled water. LDPE released the highest concentrations of Cu and Na into solution, PP released the greatest amount of Fe, and PET released the most Cr. The efficiencies of Mg and Zn release from the plastics (PP and PET) varied by solution type. Among the plastics studied, LDPE exhibited the strongest ability to adsorb metals, such as Fe, Cr, Mg, and Zn from soil solutions. The amount of metal released from the plastics was also dependent on pH, dissolved organic carbon (DOC) concentrations, and the electrical conductivity (EC) of the solutions. Moreover, plastic extracts were found to have negative effects on germination and growth in Lepidium sativum.

Estrogens and xenoestrogen residues in manure-based fertilizers and their potential ecological risks.

Optimal manure treatment aimed at usage as agricultural soil fertilizers is a prerequisite ecological pollution control strategy. In this work, livestock manure-based fertilizers were collected from 71 animal farms across 14 provinces in China. The contamination levels and potential ecotoxicological risks of residual steroid estrogens (SEs): estrone (E1), estriol (E3), 17α-estradiol (17α-E2), 17ß-estradiol (17ß-E2) and xenoestrogen (XE) bisphenol A (BPA), were investigated. The results showed that the occurrence frequencies for SEs and XE ranged from 66.67% to 100%, and the mean concentration varied considerably across the study locations. The total content of SEs and XE in Hebei province was the highest, and swine manure-based fertilizers concentrations were higher than the levels reported in other animal fertilizers. Compared with farm level manure, manure-based fertilizers are processed by composting, and the micropollutants quantities are significantly reduced (mean: 87.65 - 534.02 µg/kg). The total estradiol equivalent quantity (EEQ) that might migrate to the soil was estimated to be 1.23 µg/kg. Based on the estimated application rate of manure, 38% of the fertilizers risk quotients exceeded 0.1, indicating medium to high risks pressure on terrestrial organisms. Nonetheless, the estrogenic risk was lower in manure-based fertilizers than in manure. This study highlights the significance of proper treatment of livestock manure and designing an optimal manure fertilization strategy to mitigate the risks posed by SEs and XEs to the agroecosystems.

The promoted degradation of biochar-adsorbed 2,4-dichlorophenol in the presence of Fe(III).

Organic pollutant degradation by biochar could be promoted by Fe because of the Fenton-like reaction. However, studies have also confirmed that reactive oxygen species (ROS) play only a limited role in organic pollutant degradation by biochar. Herein, we quantitatively identified 2,4-dichlorophenol (2,4-DCP) adsorption and degradation in Fe-biochar systems and obtained degradation (k1) and adsorption rate constants (k2) by two-compartment first-order kinetics modeling. The k1 was approximately 7-10 times lower than the corresponding k2 and the positive correlation between k1 and k2 illustrated that adsorption and degradation were kinetically associated. ROS quenching only slightly inhibited 2,4-DCP degradation. Chemicals with similar structures to ROS quenchers (without quenching ability) also inhibited 2,4-DCP degradation, probably because of the competition of the active degradation sites on biochars. Electrochemical analysis and pH-impact experiments further elucidated that 2,4-DCP underwent oxidation-dominated degradation in the adsorbed phase via direct electron transfer. Fe(III) obviously increased 2,4-DCP adsorption through cation bridging and enhanced electron density by Fe-O conjugations on the biochar surface, which facilitated subsequent degradation. This study emphasized the importance of degradation on the biochar solid phase and that a breakthrough of the mass transfer bottleneck of adsorption will greatly promote degradation.

Transcriptional response of Cu-deficient barley (Hordeum vulgare L.) to foliar-applied nano-Cu: Molecular crosstalk between Cu loading into plants and changes in Cu homeostasis genes.

For safe and effective nutrient management, the cutting-edge approaches to plant fertilization are continuously developed. The aim of the study was to analyze the transcriptional response of barley suffering from Cu deficiency to foliar application of nanoparticulate Cu (nano-Cu) and its ionic form (CuSO4) at 100 and 1000 mg L-1 for the examination of their supplementing effect. The initial interactions of Cu-compounds with barley leaves were analyzed with spectroscopic (ICP-OES) and microscopic (SEM-EDS) methods. To determine Cu cellular status, the impact of Cu-compounds on the expression of genes involved in regulating Cu homeostasis (PAA1, PAA2, RAN1, COPT5), aquaporins (NIP2.1, PIP1.1, TIP1.1, TIP1.2) and antioxidant defense response (SOD CuZn, SOD Fe, SOD Mn, CAT) after 1 and 7 days of exposure was analyzed. Although Cu accumulation in plant leaves was detected overtime, the Cu content in leaves exposed to nano-Cu for 7 days was 44.5% lower than in CuSO4 at 100 mg L-1. However, nano-Cu aggregates remaining on the leaf surface indicated a potential difference between measured Cu content and the real Cu pool present in the plant. Our study revealed significant changes in the pattern of gene expression overtime depending on Cu-compound type and dose. Despite the initial puzzling patterns of gene expression, after 7 days all Cu transporters showed significant down-regulation under Cu-compounds exposure to prevent Cu excess in plant cells. Conversely, aquaporin gene expression was induced after 7 days, especially by nano-Cu and CuSO4 at 100 mg L-1 due to the stimulatory effect of low Cu doses. Our study revealed that the gradual release of Cu ions from nano-Cu at a lower rate provided a milder molecular response than CuSO4. It might indicate that nano-Cu maintained better metal balance in plants than the conventional compounds, thus may be considered as a long-term supplier of Cu.

The effect of biotransformation of sewage sludge- and willow-derived biochars by horseradish peroxidase on total and freely dissolved polycyclic aromatic hydrocarbon content.

This study analyzed the effect of enzymatic aging (horseradish peroxidase) of biochars on their content of solvent extractable (Ctot) and freely dissolved (Cfree) polycyclic aromatic hydrocarbons (PAHs). Physicochemical properties and phytotoxicity of pristine and aged biochars were also compared. The study used biochars obtained at 500 or 700 °C from sewage sludges (SSLs) or willow. Compared to SSL-derived biochars, willow-derived biochars were more susceptible to enzymatic oxidation. Aging increased the specific surface area and pore volume of most SSL-derived biochars. An opposite direction, however, was found in the willow-derived biochars. Low-temperature biochars, regardless of their feedstock, underwent physical changes, such as removal of labile ash components or degradation of aromatic structures. The enzyme caused an increase in the content of Ctot light PAHs in biochars (by 34-3402 %) and heavy PAHs (≥4 rings) in the low-temperature SSL-derived biochars (by 46-713 %). In turn, the content of Cfree PAHs decreased in aged SSL-derived biochars (by 32-100 %). In the willow-derived biochars the bioavailability of acenaphthene increased (by 337-669 %), while the immobilization degree of some PAHs was lower (25-70 %) compared to the SSL-derived biochars (32-83 %). Nevertheless, aging positively affected the ecotoxicological properties of all biochars by increasing their stimulation effects or removing their phytotoxic effects on both Lepidium sativum seed germination and root growth. Significant relationships between the changes in Cfree PAH content, pH and salinity of SSL-derived biochars and seed germination/root growth inhibition were found. The study demonstrates that the risk associated with application of SSL-derived biochars, regardless of the type of SSL and pyrolysis temperature, can be lower in terms of Cfree PAHs than in the case of willow-derived biochars. Regarding to Ctot PAHs, high-temperature SSL-derived biochars are safer than low-temperature ones. In the case of application of high-temperature SSL-derived biochars, these with moderate alkalinity and salinity will not bring risks for plants.

A novel type of biochar from chitinous Hermetia illucens waste with a built-in stimulating effect on plants and soil arthropods.

The breeding of insects generates waste in the form of insect excrement and feed residues. In addition, a specific chitinous waste in the form of insect larvae and pupae exuvia is also left. Recent research tries to manage it, e.g., by producing chitin and chitosan, which are value-added products. The circular economy approach requires testing new, non-standard management methods that can develop products with unique properties. To date, the possibility of biochar production from chitinous waste derived from insects has not been evaluated. Here we show that the puparia of Hermetia illucens are suitable for biochar production, which in turn exhibits original characteristics. We found that the biochars have a high nitrogen level, which is rarely achievable in materials of natural origin without artificial doping. This study presents a detailed chemical and physical characterization of the biochars. Moreover, ecotoxicological analysis has revealed the biochars' stimulation effect on plant root growth and the reproduction of the soil invertebrate Folsomia candida, as well as the lack of a toxic effect on its mortality. This predisposes these novel materials with already built-in stimulating properties to be used in agronomy, for example as a carriers for fertilizers or beneficial bacteria.

Microplastics identification in water by TGA-DSC Method: Maharloo Lake, Iran.

Nowadays, one of the biggest challenges is the lack of coordination between the microplastic identification methods used by researchers. To advance our global understanding of microplastic contamination and address the knowledge gaps, we require acceptable or similar identification methods or instruments designed to support the quantitative characterization of the microplastics data. In the current study, we focused on the thermogravimetric analysis (TGA) with differential scanning calorimetry (DSC) method which is usually used experimentally by other researchers, while we tried to look at this method in a real aquatic environment, Maharloo Lake and its Rivers. A number of 22 sites were chosen for sampling microplastics from water. The mean and median of total organic matter percentage for rivers samples (mean = 88%;median = 88%) was similar to the Maharloo lake (mean = 88.33%; median = 89%), suggesting the existence of a robust potential sink. The differentiation of the organic matter part into labile (e.g., carbon aliphatic and polysaccharides), recalcitrant (e.g., aromatic compounds and most plastics), and refractory fractions was implemented and the results indicated that labile organic matter was dominant in both the lake and the rivers, while recalcitrant and refractory fractions were lower. The river's average labile and refractory fractions were similar to the lake. Although the overall results of the study show combining TGA techniques with other analytical procedures can improve the technical quality of polymers, interpreting the complex information of those measurements requires a high level of expertise and the technology is still maturing.

The impact of cyclic freezing and thawing (physical aging) on properties and polycyclic aromatic hydrocarbon content in biochars.

In this study, we investigated the effect of freeze-thaw cycles of sewage sludge (SSL)- and willow-derived biochars obtained at different temperatures on their physicochemical properties and total (Ctot) and freely dissolved (Cfree) polycyclic aromatic hydrocarbon (PAH) content. In our research, we showed that the fate of Ctot PAHs depended on the type of SSL and may differ, which is determined mainly by the properties of the feedstock. The properties affect low-temperature SSL-derived biochars (500 °C) especially, in which the interactions based on π-π bonds between the PAHs and matrix during aging were weakened by newly created functional groups on the biochar surface. Additionally, the removal of ash or biochar particle fragmentation during aging increased the availability of solvent non-extractable PAHs, which resulted in an increase in the content of high molecular weight Ctot PAHs after aging. In turn, the Σ16 Cfree PAHs in biochars gradually decreased with their progressive surface functionalization, increase in specific surface area and pore volume and generally were independed on properties of feedstock and biochar. The obtained results evidence that the environmental risk associated with the use of SSL as a feedstock for biochar production is similar to or even lower than in the case when willow is used and depending on SSL type, the potential risk may be reduced or increased for low-temperature biochars.