Seasonal variation of arsenic in PM10 and PMx in an urban park: The influence of vegetation-related biomethylation on the distribution of its organic species and air quality.

Arsenic (As) levels in particulate matter (PM) are routinely monitored in cities of developed countries. Despite advances in the knowledge of its inorganic species in PM in urban areas, organic species are often overlooked with no information on their behaviour in urban parks - areas with increased potential for As biomethylation. Therefore, the aim of this study was to characterize As distribution, bioaccessibility, seasonal variation and speciation (AsIII, AsV, MMA, DMA and TMAO) in PMx-PM10 of an urban park. Two sites with different distance from the road were selected for winter and summer sampling. From the PM samples, we gravimetrically determined PM10 concentrations in the air and via ICP-MS the total As content there. To assess the portion of bioaccessible As, water extractable As content was analysed. Simultaneously, the As species in PM10 water extracts were analysed via coupling of HPLC with ICP-MS method. There was no seasonal difference in PM10 concentration in the park, probably due to the increased summer PM load related to recreational activities in the park and park design. Spatial distribution of total As in PM10 and As fractional distribution in PMx suggested that As mostly didn't originate from traffic although highest As content was observed in the fine fraction (PM2.5) related to combustion processes. However, significant winter increase of As (determined by AsIII and AsV) despite the unchanged concentration of PM10 indicated a decisive influence of household heating-related combustion and possibly influence of reduced vegetation density. As present in the PM10 was mostly in bioaccessible form. Seasonal influence of As biomethylation was clearly demonstrated on the TMAO specie during the summer campaign. Except the significant summer TMAO increase, the results also indicated the biomethylation influence on DMA. Therefore, an increased risk of exposure to organic As species in urban parks can be expected during summer.

Biodegradation of poly-3-hydroxybutyrate after soil inoculation with microbial consortium: Soil microbiome and plant responses to the changed environment.

Biodegradable plastics play a vital role in addressing global plastics disposal challenges. Poly-3-hydroxybutyrate (P3HB) is a biodegradable bacterial intracellular storage polymer with substantial usage potential in agriculture. Poly-3-hydroxybutyrate and its degradation products are non-toxic; however, previous studies suggest that P3HB biodegradation negatively affects plant growth because the microorganisms compete with plants for nutrients. One possible solution to this issue could be inoculating soil with a consortium of plant growth-promoting and N-fixing microorganisms. To test this hypothesis, we conducted a pot experiment using lettuce (Lactuca sativa L. var. capitata L.) grown in soil amended with two doses (1 % and 5 % w/w) of P3HB and microbial inoculant (MI). We tested five experimental variations: P3HB 1 %, P3HB 1 % + MI, P3HB 5 %, P3HB 5 % + MI, and MI, to assess the impact of added microorganisms on plant growth and P3HB biodegradation. The efficient P3HB degradation, which was directly dependent on the amount of bioplastics added, was coupled with the preferential utilization of P3HB as a carbon (C) source. Due to the increased demand for nutrients in P3HB-amended soil by microbial degraders, respiration and enzyme activities were enhanced. This indicated an increased mineralisation of C as well as nitrogen (N), sulphur (S), and phosphorus (P). Microbial inoculation introduced specific bacterial taxa that further improved degradation efficiency and nutrient turnover (N, S, and P) in P3HB-amended soil. Notably, soil acidification related to P3HB was not the primary factor affecting plant growth inhibition. However, despite plant growth-promoting rhizobacteria and N2-fixing microorganisms originating from MI, plant biomass yield remained limited, suggesting that these microorganisms were not entirely successful in mitigating the growth inhibition caused by P3HB.

The impacts of mining on soil pollution with metal(loid)s in resource-rich Mongolia.

As Mongolia is considered one of the most resource extraction-dependent countries globally, significant mining-related environmental and human health risks are expected. The aim of this study was to (I) assess the impacts of mining on soil pollution with metals in Mongolia's key coal mining towns (Baganuur, Nalaikh and Sharyn Gol) and (II) review the current knowledge on soil pollution with metal(loid)s and related health risks in Mongolia. The results showed predominantly low soil contents of Cd, Cu, Pb and Zn and a related absence of severe pollution and potential health risk in the coal mining towns. Urban design, rather than the presence of mines, controlled the pollution distribution. Despite the methodological shortcomings of several studies on soil pollution in Mongolia, their results suggest a similarly low threat in the three largest cities (Ulaanbaatar, Darkhan, Erdenet) and several mining areas. While the generally highlighted risk of As seems like an artificially escalated issue, the content of Cr in urban soil may be a neglected threat. Further pollution research in Mongolia should focus on street dust and drinking water pollution.

Influence of Poly-3-hydroxybutyrate Micro-Bioplastics and Polyethylene Terephthalate Microplastics on the Soil Organic Matter Structure and Soil Water Properties.

Adverse effects of microplastics on soil abiotic properties have been attributed to changes in the soil structure. Notably, however, the effects on the supramolecular structure of soil organic matter (SOM) have been overlooked, despite their key role in most soil properties. This work accordingly investigated the influence of plastic residues at various concentrations on the SOM supramolecular structure and soil water properties. To model plastic residues of micro-bioplastics, spherical or spherical-like poly-3-hydroxybutyrate (PHB) was used, while polyethylene terephthalate (PET) was used as a model of conventional microplastics. The results suggest that both types of plastic residues affect SOM properties, including physical stability (represented by water molecule bridges), water binding (represented by decreased desorption enthalpy or faster desorption), and the stability of SOM aliphatic crystallites. The results further showed that the polyester-based microplastics and micro-bioplastics affected the SOM abiotic characteristics and that therefore the observed effects cannot be attributed solely to changes in the whole soil structure. Notably, similar adverse effects on SOM were observed for both tested plastic residues, although the effect of PHB was less pronounced compared to that of PET.

Influence of beech and spruce on potentially toxic elements-related health risk of edible mushrooms growing on unpolluted forest soils.

Atmospheric deposition-related potentially toxic elements (PTEs) can contaminate mountain forest ecosystems. The influence of tree species is being increasingly recognised as an important factor in the deposition loads in forest soils. However, relevant modelling studies about the forest pollution with PTEs, concerning the tree species composition, are lacking. The aim of this study was to evaluate the effect of European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) H. Karst.) on soil and mushroom pollution and the associated health risks to define their significance for pollution modelling. Therefore, topsoil samples and samples of eight edible mushroom species were taken from 51 mature beech- and spruce-dominated stands. The results showed that forest composition had an indirect influence on the PTEs contents in the topsoil; it significantly differentiated the relationship between PTEs and soil C as the beech stands showed significantly increasing PTEs content with increasing C content. Despite the absence of soil pollution, above-limit levels of Cd and Zn were found in mushrooms. The total content of PTEs in mushrooms posed a potential health risk to consumers in 82% of the samples. The most Cd-contaminated and potentially the riskiest species for consumption was Xerocomellus pruinatus (Fr. and Hök) Sutara. The results suggest that the source of PTEs for mushrooms is not only the soil but probably also the current wet deposition. The influence of the forest type on the accumulation of PTEs in mushrooms was confirmed mainly due to the strongly divergent behaviour of Zn in beech- vs. spruce-dominated stands. The results point to the need to evaluate mushroom contamination even in the contamination-unburdened forest areas. For future modelling of PTEs pollution in forests, it is necessary to differentiate the tree species composition.

Can rail transport-related contamination affect railway vegetation? A case study of a busy railway corridor in Poland.

Rail transport is considered a serious risk to the environment; however, its environmental impact has been addressed insufficiently with many resulting uncertainties. A busy railway corridor was used to determine if the side of a railway track could distort the assessment of soil contamination with potentially toxic elements (PTEs) and if soil phytotoxicity changes up to 50 m away from the track. The studied soils showed a moderate to heavy level of contamination with Cu, Ni, Pb and Zn. Cu, Ni and Zn content decreased significantly with the distance from the track while Pb content increased slightly, probably because the Pb came predominantly from exhaust gases, while the source of the remaining elements was the abrasion of railway infrastructure components. The side of the railway track proved to be a significant factor that influenced Ni and Pb content in particular. The phytotoxicity test predominantly showed a slight inhibition of plant growth with a maximum value reaching 70.4% but with an absence of significant differences in phytotoxicity between the distances. The ecological risk assessment did not reveal a serious threat to the environment from the PTEs in the soil. Based on the results, it is appropriate to define a heavily polluted zone at a minimum distance of 50 m from the track, and both sides of the railway track should be assessed so that the actual level of contamination is not underestimated. Further research is needed on this issue urgently due to the severe and hitherto overlooked environmental risks associated with rail transport.

Assessment of Soil Contamination with Potentially Toxic Elements and Soil Ecotoxicity of Botanical Garden in Brno, Czech Republic: Are Urban Botanical Gardens More Polluted Than Urban Parks?

Though botanical gardens are an important and widely visited component of urban green spaces (UGS) worldwide, their pollution is rarely studied. The aim of this study was to assess botanical garden soil contamination and ecotoxicity and to evaluate whether urban botanical gardens are more contaminated than urban parks. Soil assessments showed serious contamination with Cd, Pb and Zn, emitted predominantly by traffic, agrochemicals and past construction and demolition waste. The discovery of hazardous historical ecological burden in the UGS calls for the necessity of detailed surveys of such areas. Despite prevailing moderate-to-heavy contamination, the soil was only slightly ecotoxic. Maximum immobilisation inhibition of Daphnia magna reached 15%. Growth of Sinapis alba L. was predominantly stimulated (73%), and Desmodesmus subspicatus Chodat was exclusively stimulated, possibly due to soil alkalinity and fertiliser-related nutrients. The hypothesis of a higher contamination of urban botanical gardens compared to urban parks was confirmed. However, urban parks can face a greater risk of soil ecotoxicity, hypothetically due to decreased activity of soil organisms resulting from adverse soil conditions caused by active recreation. The results highlight the need for an increased focus on botanical and ornamental gardens when assessing and managing UGS as areas potentially more burdened with contamination.

A critical review of the possible adverse effects of biochar in the soil environment.

Biochar has received extensive attention because of its multi-functionality for agricultural and environmental applications. Despite its many benefits, there are concerns related to the long-term safety and implications of its application, mainly because the mechanisms affecting soil and organism health are poorly quantified and understood. This work reviews 259 sources and summarises existing knowledge on biochar's adverse effects on soil from a multiangle perspective, including the physicochemical changes in soil, reduced efficiency of agrochemicals, potentially toxic substances in biochar, and effects on soil biota. Suggestions are made for mitigation measures. Mixed findings are often reported; however, the results suggest that high doses of biochar in clay soils are likely to decrease available water content, and surface application of biochar to sandy soils likely increases erosion and particulate matter emissions. Furthermore, biochar may increase the likelihood of excessive soil salinity and decreased soil fertility because of an increase in the pH of alkaline soils causing nutrient precipitation. Regarding the impact of biochar on (agro)chemicals and the role of biochar-borne toxic substances, these factors cannot be neglected because of their apparent undesirable effects on target and non-target organisms, respectively. Concerning non-target biota, adverse effects on reproduction, growth, and DNA integrity of earthworms have been reported along with effects on soil microbiome such as a shift in the fungi-to-bacteria ratio. Given the diversity of effects that biochar may induce in soil, guidelines for future biochar use should adopt a structured and holistic approach that considers all positive and negative effects of biochar.

Polluted brownfield site converted into a public urban park: A place providing ecosystem services or a hidden health threat?

The conversion of old brownfield sites into places once again serving society is becoming an upward global trend, especially in urban areas. Due to the increasingly growing pressure on the expansion of urban green spaces, such sites can become, for instance, urban parks. The aim of the study was to assess whether the solution is appropriate and if it does not pose a potential health risk. Heavy pollution of soils was found out by means of the example of the urban park newly established in a reclaimed area of a historic mining town. The high average values in the topsoil were found out mainly in As (132 mg/kg), Cd (6.8 mg/kg), Pb (535 mg/kg) and Zn (1604 mg/kg). The assessment of the non-carcinogenic health risk has revealed possible As-related adverse health effects in children even at irregular park visits. According to the carcinogenic risk assessment, As, Cd, Cr and Ni can be ranked in the category of an acceptable total risk for regulatory purposes. The health status of park vegetation as a significant component of the urban ecosystem was also assessed. Soil phytotoxicity brought about severe damage to the seedlings, with a mortality rate of up to 84% locally. The results indicate that heavily polluted brownfield sites with historic mining-related activities are not suitable for establishing urban parks even after reclamation and nature-based solutions may not be invariably appropriate. Based on the findings, the management steps that ought to be implemented in the process of brownfield redevelopment into the urban park even after its establishment have been highlighted in order to minimize the health risk to park visitors while providing the required ecosystem services by vegetation.

Insight into metal immobilization and microbial community structure in soil from a steel disposal dump phytostabilized with composted, pyrolyzed or gasified wastes.

The soil system is a key component of the environment that can serve as a sink of pollutants. Using processed waste for aided phytostabilization of metals (HMs) in contaminated soils is an attractive phytoremediation technique that integrates waste utilization and recycling. In this study, we evaluated the effect of biologically and thermally processed wastes, i.e. sewage sludge compost (CSS), poultry feather ash (AGF) and willow chip biochar (BWC), on phytostabilization of contaminated soil from a steel disposal dump. Greenhouse experiments with Lupinus luteus L. and amendments (dosage: 3.0%, w/w) were conducted for 58 days. Soil toxicity was evaluated with Ostracodtoxkit and Phytotoxkit tests. At the end of the experiment, soil pH, plant biomass yield, and HM accumulation in plant tissues were determined. HM distribution, HM stability (reduced partition index) and potential environmental risk (mRI index) in the soil were assessed. During phytostabilization, changes in the diversity of the rhizospheric bacterial community were monitored. All amendments significantly increased soil pH and biomass yield and decreased soil phytotoxicity. AGF and BWC increased accumulation of individual HMs by L. luteus roots better than CSS (Cu and Cr, and Ni and Zn, respectively). The soil amendments did not improve Pb accumulation by the roots. Improvements in HM stability depended on amendment type: Ni and Pb stability were improved by all amendments; Zn stability, by AGF, and BWC; Cd stability, by AGF; and Cr stability, by BWC. AGF reduced the mRI most effectively. Microbial diversity in amended soils increased with time of phytostabilization and was up to 9% higher in CSS amended soil than in control soil. AGF application favored the abundance of the genera Arenimonas, Brevundimonas, Gemmatimonas and Variovorax, whose metabolic potential could have contributed to the better plant growth and lower mRI in that soil. In conclusion, AGF and BWC have great potential for restoring steel disposal dump areas, and the strategies researched here can contribute to achieving targets for sustainable development.

Human health and ecological risk assessment of trace elements in urban soils of 101 cities in China: A meta-analysis.

Urban soils pollution by trace elements arouses the growing interest in China. The aim of this study was to assess urban soil pollution by As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in China and the possible impacts on urban inhabitants and urban green spaces (UGS). Data from more than 17,000 samples were applied to characterize the status of 101 cities. The pollution assessment proved that 11% of the cities are heavily polluted. According to the Hazard Index, the value of risk for the infant population in 15 cities exceed the standardly accepted tolerable levels. The carcinogenic risk assessment demonstrated the potential threat in the cities with the total population approximately 20,566,900. Cr and As were detected to be the most hazardous elements. UGS may be seriously threatened by trace elements toxicity in 38 cities. Cd was found to be the riskiest element for UGS. Ecosystem services of UGS can be significantly disrupted under the current situation in China and their status is expected to deteriorate in the future. For this reason, it is essential to alter the policy of the urbanization process and develop functional concepts of urban green infrastructures adapted to the high level of contamination which shall improve human well-being in China.

Successful Outcome of Phytostabilization in Cr(VI) Contaminated Soils Amended with Alkalizing Additives.

This study analysed the effect of three alkalizing soil amendments (limestone, dolomite chalcedonite) on aided phytostabilization with Festuca rubra L. depending on the hexavalent chromium (Cr(VI)) level in contaminated soil. Four different levels of Cr(VI) were added to the soil (0, 50, 100 and 150 mg/kg). The Cr contents in the plant roots and above-ground parts and the soil (total and extracted Cr by 0.01 M CaCl2) were determined with flame atomic absorption spectrometry. The phytotoxicity of the soil was also determined. Soil amended with chalcedonite significantly increased F. rubra biomass. Chalcedonite and limestone favored a considerable accumulation of Cr in the roots. The application of dolomite and limestone to soil contaminated with Cr(VI) contributed to a significant increase in pH values and was found to be the most effective in reducing total Cr and CaCl2-extracted Cr contents from the soil. F. rubra in combination with a chalcedonite amendment appears to be a promising solution for phytostabilization of Cr(VI)-contaminated areas. The use of this model can contribute to reducing human exposure to Cr(VI) and its associated health risks.

The impact of tourism on extremely visited volcanic island: Link between environmental pollution and transportation modes.

The enormous tourism boom raises concern about possible negative environmental impacts worldwide. One of the risks posed by tourism may be heavy metal pollution. On the example of the volcanic island of Santorini, a popular tourist destination, pollution of soils categorized according to the tourism load was monitored. Significant anthropogenic contamination by heavy metals, especially Cu, Cr and Pb, was found out. This contamination may constitute a moderate ecological risk to the island ecosystems. Tourism has been shown to be a significant pollution factor as evidenced by the contaminated soils near the airport. Simultaneously, airport traffic has been proved to be an important emitter of Co, Cr and especially Zn. The comparison with other volcanic islands has shown that on Santorini the content of heavy metals in soils is significantly lower, despite frequently higher tourism intensity. On this basis, it can be concluded that in case of volcanic islands the dominant factor determining the content of heavy metals in the soil is the parent rock. Given high and ever-increasing intensity of tourism on the island, it can be assumed that soil contamination will continue to rise rapidly. Therefore, without proper steps reducing tourism, increase in soil degradation, growing negative impacts on local ecosystems as well as on the quality of produced wine can be expected on Santorini.

Assessment of phytotoxicity, environmental and health risks of historical urban park soils.

Urban soil areas can be contaminated with potentially dangerous heavy metals (HM), which might have got there by means of the human activity. The aim of the present study was to determine the contamination level of the city park soils and its impact on urban ecosystem. The indices assessing soil contamination such as Enrichment Factor (EF), Geoaccumulation Index (Igeo), Nemerow Pollution Index (IPIN), and indices assessing health risks, namely Hazard Index (HI) and Carcinogenic Risk (CR), have been calculated. Furthermore, the phytotoxic effect of the soil samples has been determined. The soil contains in average 58.6 mg/kg Zn, 0.3 mg/kg Cd, 27.2 mg/kg Pb and 16.6 mg/kg Cu. Based on EF index, it has been confirmed that the increased amounts of Zn, Cd and Pb in the soil are of the anthropogenic origin. The soil may be classified as moderately to strongly polluted in the case of Zn and Pb according to Igeo. Nevertheless, soil contamination in the park is at a safe level as per IPIN. Based on HI and CR indices, it is possible to state that the soil in the park does not pose any health risks. Subject to the outcomes of the toxicity test, the concentrations of HMs found out in the soils are not inhibitory for plants.