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Plastic mulch is a commonly employed technique in agriculture to enhance crop production. Given the persistence of plastic residues in soil, bioplastics offer a potential alternative. Unfortunately, little is known about the medium-term consequences of both plastic and bioplastic mulches on soil properties. This study aimed to assess the medium-term consequences of plastic and bioplastic mulches and their replacement on soil properties. To this aim, the impact of conventional plastic (polyethylene, CP) and biodegradable plastic (BP) mulches on soil's abiotic (pH, water content, total and organic carbon and total nitrogen contents) and biotic (microbial biomass, microbial respiration, enzymatic activities and microarthropod communities) properties after 2 years of exposure (T1) and after 3 (T2) and 6 (T3) months of mulch replacement was investigated. Moreover, uncovered soils were assessed as a control. The results highlighted that the samples were more significantly impacted by exposure time to mulches than by the different kinds of mulches. The replacement of both mulches (T2 and T3) decreased the content of C and increased the microbial biomass and activities; moreover, the mulch replacement changed the microarthropod community composition with a decrease of Collembola and an increase of Oribatida and Gamasida, especially in soils covered by biodegradable plastic mulches. Further investigations are needed to better understand the long-term impact of mulches on soil biota in order to prove the potential ecological implications of transitioning to sustainable alternatives. [ABSTRACT FROM AUTHOR]

Recently, due to rapid industrialization and urbanization, many studies have focused on the assessment of soil metal contamination. The present research aimed to investigate the concentration of potentially hazardous elements (Al, Cr, Cu, Fe, Mg, Mn, Ni, Pb, V and Zn) in three different areas (forest, wildfire forest and urban) of the Mediterranean region. Contamination levels were further assessed calculating different indices: contamination factor (CF), geo-accumulation index (GI) and ecological risk (E). The results showed high concentrations of V, Mg and Mn in forest and wildfire forest soils, as well as high concentrations of Al, Fe, Ni, Pb and Zn in urban soils. According to the contamination indices, Pb exceeded the background level in both wildfire forest and urban soils. According to human risk assessment, inhalation appeared the main route of exposure of metals in soils, especially for children. The overall cancer risk was higher than the safe level, especially for Pb. Different relationships were found between the contamination indices and the potential risk of carcinogenic effects according to the diverse metal concentrations. Particularly, wildfire soils showed human health risks mainly linked to Pb, Cu and Cr contaminations, due to human activities, and Ni, due to both anthropogenic and pedogenetic input. Instead, the urban soils showed that Zn contamination, mainly related to urban traffic, influenced the potential carcinogenetic risk in this area. The carcinogenic risk was higher than acceptable values for all the metals assessed. These findings highlighted the need to develop further management practices to protect soils from metal pollution and reduce human health risks. [ABSTRACT FROM AUTHOR]

[Display omitted] • Soil nutrient stoichiometry is threatened by soil degradation phenomena. • Microclimatic condition and vegetation affect soil nutrient balance. • Fire effects on microbial biomass and activity persist in the first three years. • In fall and spring seasons, soils sampled under trees exhibit N and P deficiency. • Microbial activity was inhibited in spring both under trees and shrubs. Mediterranean soils are affected by degradation phenomena, exacerbated by anthropic disturbance. These ecosystems are affected by peculiar climatic conditions, characteristic vegetation and frequent fire that with the anthropic activities can compromise soil nutrient status. Studies concerning the nutrients stoichiometry in Mediterranean area are scarce, therefore the present research aim to fill the gap about the effect of seasonal variations, vegetation cover and fire occurrences on soil nutrient balance and microbial biomass and activity. The sampling was performed inside the Vesuvius National Park across 24 sites during two seasons (Fall and Spring), under trees and shrubs and in burned and unburned areas. Soils were characterized for carbon (C), nitrogen (N), phosphorous (P) and potassium (K) concentrations, for bacterial and fungal biomass (Eub and Fungi) and for microbial activities (respiration, hydrolase: HA, dehydrogenase: DHA, β-glucosidase: β-glu and urease: U). The results showed that, both in Fall and Spring, high C:N (18.7), C:P (130) and N:P (6.74) ratios were observed in soils under trees. Both in soils under trees and shrubs, low eubacterial biomass (trees: 90.2 ng g−1 w.w.; shrubs: 44.4 ng g−1 w.w.), respiration (trees: 0.24 mg CO 2 g−1 d.w. min−1; shrubs: 0.14 mg CO 2 g−1 d.w. min−1) and hydrolase (trees: 37.0 mmol FDA g−1 d.w. min−1; shrubs: 11.9 mmol FDA g−1 d.w. min−1) activities were observed in Spring. Fire effect was evident only in Fall where low values of eubacterial biomass (667 ng g−1 w.w.) and respiration activity (0.60 mg CO 2 g−1 d.w. min−1) were observed in burnt soils. In conclusion, the seasonal variations and the vegetation cover appeared the main environmental factors that affect nutrient stoichiometry and microbial biomass and activity in Mediterranean soils. It is necessary to monitor Mediterranean soils during different seasons and encourage the growth of native vegetation to enhance nutrient cycling and maintain soil health. [ABSTRACT FROM AUTHOR]

Vanadium toxicology is a topic of considerable importance as this metal is widely used in industrial and biomedical fields. However, it represents a potential emerging environmental pollutant because wastewater treatment plants do not adequately remove metal compounds that are subsequently released into the environment. Vanadium applications are limited due to its toxicity, so it is urgent to define this aspect. This metal is associated with sea urchin embryo toxicity as it perturbs embryogenesis and skeletogenesis, triggering several stress responses. Here we investigated its bioaccumulation and the correlation with cellular and molecular developmental pathways. We used cytotoxic concentrations of 1 mM and 500 μM to perform quantitative analyses, showing that vanadium accumulation interferes with calcium uptake during sea urchin development and provokes a disruption in the biomineralization process. At the end of the whole treatment, the accumulation of vanadium was about 14 and 8 μg for embryos treated respectively with 1 mM and 500 μM, showing a dose-dependent response. Then, we monitored the cell signaling perturbation, analyzing key molecular markers of cell survival/cell death mechanisms and the DNA fragmentation associated with apoptosis. This paper clarifies vanadium's trend to accumulate directly into embryonic cells, interfering with calcium uptake. In addition, our results indicate that vanadium can modulate the ERK pathway and activate a cell-selective apoptosis. These results endorse the sea urchin embryo as an adequate experimental model to study metal-related cellular/molecular responses. [ABSTRACT FROM AUTHOR]

As they quickly respond to environmental conditions, soil enzymes, involved in nutrient cycles, are considered good indicators of soil quality. The Mediterranean area is a peculiar environment for climatic conditions and for fire frequency. Therefore, the research aimed to evaluate the role of seasonality and fire on enzymatic activities (i.e., hydrolase, dehydrogenase, and β-glucosidase) in soils covered by herbs, black locust, pine, and holm oak. In addition, the main soil abiotic properties that drive the enzymatic activities were also investigated. In order to achieve the aims, surface soils were collected in unburnt and burnt areas and characterized for water and organic matter contents, pH, concentrations of C and N, and available fractions of Al, Ca, Cu, Fe, Mg, Mn, Na, and Pb. The results highlighted that the soil enzymatic activities were mainly affected by seasonality more than by fire; in unburnt soils, their main drivers were nutrient availabilities, whereas, in burnt soils they were pH, water and organic matter contents, C and N concentrations, and both nutrient and metal availabilities. Finally, holm oak, as compared with herbs, pine, and black locust, conferred higher stability to soils that were affected by seasonality and fire. [ABSTRACT FROM AUTHOR]

The intensive wildfires recurring in the Mediterranean area modify soil physico-chemical properties, in turn inducing changes in soil microbial abundance and activity. Soils were sampled from burnt and adjacent unburnt sites within Vesuvius National Park 1 year after a large wildfire occurred in summer 2017. The aims of the present study were to evaluate the effects of fires on soil characteristics and to investigate whether different plant types contribute to mitigating or enhancing these effects. The results showed lower organic matter and water content and a higher C/N ratio in burnt than in unburnt soils. In particular, this trend was the same for all the plant types investigated, with the exception of soils covered by black locust tree and holm oak, which showed a higher C/N ratio in unburnt than in burnt soils. In soils covered by holm oaks, a shift in the bacterial and fungal fractions occurred between burnt and unburnt soils, whereas the amount of ammonia oxidisers was notably higher in burnt than in unburnt soils covered by black locusts; the highest N concentration was also measured in burnt soils covered by black locusts. The burnt soils showed a lower metabolic quotient and a higher rate of organic carbon mineralisation compared with unburnt soils, and this trend was particularly evident in soils under herbaceous plants. The findings suggest that soils covered by herbaceous species are more sensitive to fire effects and less able to restore their functionality compared with soils covered by trees. Wildfires seem to amplify the differences for quantity and quality of soil organic matter and microbial amount and activity in soils under herbaceous and tree covers. This study investigated soil properties and microbial communities after fires that occurred in the summer of 2017 in Vesuvius National Park. Soils covered by herbaceous species, compared with those covered by trees, seem to be more sensitive to the overall variations owing to fire, and less able to restore their functionality – probably a result of the lowest microbial abundance and higher carbon losses. [ABSTRACT FROM AUTHOR]

Litter decomposition mobilizes nutrients that sustain ecosystem productivity, but decomposition by‐products may also hamper root proliferation by phytotoxicity. The aim of this study was to assess the litter substrate preferences of tropical tree seedlings in relation to litter chemical traits. We characterized 44 litter types (11 species at four decomposition ages; 0, 30, 90 and 180 days) for nutrients (N, P, K, Mg, Mn, Na, Fe and Zn) and proximate chemical parameters (cellulose, extractive, lignin and C) and tested the effect of such litter materials on seedling root growth of Albizia procera, Dalbergia sissoo and Terminalia arjuna. Albizia procera root growth was inhibited by all litter types and ages, including conspecific materials, while different heterospecific litters had inhibitory or stimulatory effect on D. sissoo and T. arjuna root growth, compared to the control. Interestingly, inhibitory and stimulatory effects of heterospecific litters significantly changed with litter age, although with no clear‐cut pattern among target species and litter species and age, while conspecific litters consistently inhibited root growth when aged, but not when fresh. Litter nutrient, extractive, C, cellulose and lignin showed no consistent association with root growth of tested plants. Albizia procera root growth was positively associated with Na content and N:P ratio. Dalbergia sissoo root growth was positively associated to C:N and lignin:N ratios, and negatively to K, Na and Zn content. Finally, T. arjuna root was positively associated to cellulose and N:P ratio, but negatively to extractive. We conclude that studied nutrient, cellulose and lignin do not consistently explain the species‐specific response of root of tree seedlings to decomposing litter. [ABSTRACT FROM AUTHOR]

Environmental context: Polycyclic aromatic hydrocarbons (PAHs) are widespread organic pollutants that tend to accumulate in soil. We developed an environmentally friendly analytical method for PAHs to evaluate human health risks associated with their presence in soils. The method is feasible for the analysis of soils with widely varying PAH contamination levels, and is well suited to environmental monitoring studies of relevance to human health. A microwave-assisted extraction, with a dispersive solid-phase purification step followed by programmed temperature vaporisation–gas chromatography–tandem mass spectrometry, is proposed as an environmentally friendly, simple and cheap analytical method for polycyclic aromatic hydrocarbons (PAHs) in soil. Different extraction and clean-up operating variables were tested to achieve satisfactory analytical performances: trueness from 92 to 114 %, limit of quantification (LOQ) from 0.4 to 2 µg kg−1 for most PAHs and intermediate precision, calculated as relative standard deviation (RSD), below 10 %. The method was validated using both Certified Reference Material and real soil samples collected at sites subjected to different human activities. PAH contents ranged from 0.11 (in holm oak forest soil) to 1 mg kg−1 d.w. (in an industrial soil) according to the anthropic gradient. The soil PAH contents measured were used to estimate the risk to human health, which suggested the exposure to the PAHs in soil as a potential risk for human health, especially at the industrial site. The feasibility of the method for soils with different PAH contamination degrees makes it relevant in monitoring programs. Environmental context. Polycyclic aromatic hydrocarbons (PAHs) are widespread organic pollutants that tend to accumulate in soil. We developed an environmentally friendly analytical method for PAHs to evaluate human health risks associated with their presence in soils. The method is feasible for the analysis of soils with widely varying PAH contamination levels, and is well suited to environmental monitoring studies of relevance to human health. [ABSTRACT FROM AUTHOR]

[Display omitted] Soil microarthropods play essential roles in soil functioning and they are considered useful indicators of soil metal contamination, as they quickly respond to environmental changes. The toxicity of metals depends on their fractions, but few studies have been conducted on the responses of microarthropods to different metal fractions. The study aimed to assess the response of the soil microarthropods to the soil metal fractions (exchangeable: available for organisms, reducible: associated to Fe-Mn oxides, oxidizable: associated to organic matter) under different Mediterranean vegetation covers. To reach the aim, the soils of different vegetation covers (holm oak, pine, black locust and herbs) were analysed for pH, water content, total C, N and P and C org , NH 4 + and P assimilable contents, the exchangeable (F1), reducible (F2) and oxidizable (F3) fractions of Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, V and Zn and the microarthropod taxonomic and functional indices. The results showed that, regardless the vegetation cover, the F2 and F3 of Ca, Cr, Cu, Fe, K, Mg, Mn, V and Zn significantly inhibited the density of microarthropods, favouring the functional traits typical of disturbed environments. The element F1, except for Mn, slightly impacted on the microarthropod community. In addition, the soils under trees positively influenced the taxonomic and functional indices of the microarthropod community where higher contents of C org and macronutrients were observed. Several taxa were differently impacted by three metal fractions of Al, Ca, Fe and K; in particular, Formicidae were favoured, whereas Diplopoda and Isopoda were favoured by Ca, Fe and K and inhibited by Al concentrations. The present research demonstrated that stable fractions (F2 and F3) of metals, instead to available one, exert a strong impact of microarthropod community. This leaded to change in microarthropod community assemblage, favouring taxa and traits typical of disturbed environments. [ABSTRACT FROM AUTHOR]

Plants of the urban environment are exposed to a wide range of pollutants, including heavy metals. This research studies in situ the eco-physiological and antioxidant responses of holm oak ( Q. ilex) leaves to Pb and Cd to assess the mechanisms of metal tolerance in this species, widely used as biomonitor. Leaves of plants grown at parks and roadsides were analyzed for photosynthetic activity, Pb and Cd concentration in tissues and cell-free extracts, thiol groups, D1 and Rubisco protein content, ascorbic acid (AsA) amount, and catalase (CAT) activity. The main results evidenced that Cd concentration was higher in leaves collected at the park out from the downtown; whereas Pb was most abundant in leaves sampled at the roadside nearby the highway. Pb in cell-free extracts was higher in park than in roadside leaves. Although Cd in the leaf tissues was twofold lower than Pb, it was more abundant than Pb in cellular extracts deprived of all particulate matter. Leaves responded to different concentration of Cd and Pb modulating some eco-physiological and biochemical traits, roadside leaves showed reduced leaf lamina, higher content of photosynthetic pigments, hydrogen peroxide, and AsA, as well as higher CAT activity compared to park leaves. In the roadside leaves, a stress condition for photosynthetic apparatus can be hypothesized on the basis of the decline of photochemical activity, the increase of NPQ, and the reduction of Rubisco and D1 protein content. The elevated presence of thiol groups in these leaves suggests a possible role of Pb and Cd in activation of antioxidant responses. [ABSTRACT FROM AUTHOR]

• Soil abiotic properties did not recover the pre-fire values after two years since fire. • Holm oak enhanced the recovery of the soil abiotic properties. • Microbial community in soils under herbaceous and black locust showed low resistance. • Fungal community showed low resistance at short-time and high resilience at long-time. • Soils under holm oak appeared the most resistant to wildfire. In Mediterranean areas, fires are accelerators of soil degradation and the definition of the time extent to re-establish the soil community is a great challenge. The aims of the research were to evaluate, during two years after a fire: i) the potential recover of the soil abiotic properties; ii) the stability (resistance or resilience) of the soil microbial community; iii) the potential role of different plant covers on soil recover capability. To reach the aims, soil properties as organic matter content, C and N concentrations, microbial (MB) and fungal (FB) biomasses, respiration (Resp) and coefficient of endogenous mineralization (CEM) were measured twelve, fifteen, eighteen and twenty-four months after fire, and were compared to those in pre-fire soils. The results showed that the MB was less resistant in soils under herbs and black locust, and more resilient under pine and holm oak; FB showed low resistance till one year after fire regardless to the plant cover, and high resilience at two years after fire, especially under holm oak and pine; Resp greatly slowed down and did not recover the initial values regardless to the plant cover; CEM resisted to fire in soils under different plant covers. In conclusion, the soil abiotic properties were strongly affected by plant covers, whereas the biotic ones also by the time since fire. Finally, soils under holm oak were the most fire resistant. [ABSTRACT FROM AUTHOR]

The assessment of Technosols quality in urban environments is pivotal for the maintenance of ecosystems impacted by human activities. The study was performed on Technosols constructed in experimental mesocosms in the suburban area of Naples (Southern Italy) to highlight changes in the main soil properties over eight years and to identify the most suitable indices at quality monitoring. In this study, several chemical, biological, and integrated indices were analysed to evaluate the mineral accumulation, potential ecological risk, edaphon activity, fertility, and the overall soil quality. The Technosols showed alkaline pH, nitrogen ranged from 24.5 to 39.5 g kg−1, high organic matter contents above 40 g kg−1, and there were no evident processes of soil compaction. Heavy metals (Cr, Cu, Fe, Mg, Mn, Ni, Pb, and Zn) did not exceed the thresholds defined by the Italian law for urban soils, despite their volcanic components. During eight years, the chemical indices depicted changes in the elements balance and increase in ecological risk; the biological indices indicated a reduction in the fungal fraction (fivefold) and in the resources utilisation and carbon storage. The soil quality index with all parameters highlighted the reduction in the soil quality (from 0.78 to 0.65) due to the decrease of the chemical quality, the increase of microbial stress conditions, and changes of the microbial composition, underlining the importance of integrating chemical and biological information for monitoring Technosols. [ABSTRACT FROM AUTHOR]

Mediterranean regions, because of climate and vegetation, are affected by high incidence of wildfires that modify soil characteristics. The aims of the present research were to investigate: 1) the phytotoxicity of soils collected before and after fire; ii) the probable variations in phytotoxicity of soils under different pre-existent vegetation covers (black pines, black locusts, holm oaks and herbaceous); iii) the probable variations in phytotoxicity of surface (0–10 cm) and deep (10–20 cm) soils. The impact of fires on soil phytotoxicity was estimated through root elongation, seed germination and germination index of Sorghum saccharatum L. and Lepidium sativum L. The research was performed inside the Vesuvius National Park (Naples, Southern Italy). The results highlighted that S. saccharatum L. was more sensitive to the effects due to fires. In fact, the assays performed by S. saccharatum L. highlighted a transition from inhibitory effects before fire to stimulating effects after fire, lower values for soils under black pines and holm oaks, and higher toxicity in deep than surface layers of soils. • S. saccharatum L. more than L. sativum L. was useful to show toxicity in burned soils. • S. saccharatum L. test showed low toxicity in soils under black pines and holm oaks. • Two of the three endpoints of S. saccharatum L. showed higher toxicity in deep soil. [ABSTRACT FROM AUTHOR]

• Black locust spread affects soil properties regardless fire and native plant cover. • The growth of soil bacterial community is promoted by the black locust trees. • Black locust invasion and fire occurrence improves soil element availability. • Fire promotes the changes due to the spread of black locust in soils. • Black locust invasion reduces the efficiency of carbon utilisation in shrublands soil. The combined action of alien plants invasion and fire occurrence can strongly alter local biodiversity and soil functions especially in the Mediterranean area. In this context, the goal of the study was to assess the effects of the invasive black locust (Robinia pseudoacacia L.) spread on soil characteristics, especially soil microbial community responses, in some Mediterranean shrublands and pine forests subjected to both a slow natural invasion and a fast fire-induced invasion. The soil sampled in all stands, regardless type of black locust invasion, showed increasing values of pH, water holding capacity and bulk density as compared to soil of pure shrublands and pine forests. Soil organic matter content approximately doubled in stands invaded by black locust trees (from 4.3 and 9.0 % in shrublands and from 5.3 and 14.5 % in pine forests after fire respectively). A similar trend was observed for the soil nitrogen content with values of 2.9 and 8.2 mg g−1 in pure and invaded shrublands after fire respectively and values of 3.8 and 5.4 mg g−1 in pure and invaded pine after fire. Moreover, the combined effect of black locust invasion and fire occurrence improved soil content and availability of the investigated elements (Ca, Cu, Fe, K, Mg, Mn, Na). In addition, the invasion seemed to stimulate microbial growth, by promoting especially the bacterial component regardless of the plant cover and fire occurrence. A significant decrease of microbial respiration was observed only in invaded pine forests (0.18 mg CO 2 g−1 d-1) as compared to pure forests (0.32 mg CO 2 g−1 d-1). On the other hand, in all invaded shrublands a reduced efficiency of carbon resource utilisation and a high stress condition of the microbial community were evident. However, the combined impact of black locust invasion and fire occurrence does not show specific changes in the investigated stands. Fire confirms and, sometimes, promotes the changes due to the spread of black locust in both shrublands and pine forests soils. [ABSTRACT FROM AUTHOR]

• Technosols in a short time show an important C accumulation in urban area. • Soil spectroscopy can provide a quick estimate of anthropogenic influence. • Vis–NIR spectra can be used to predict the content of microbial biomass and activity. Soil biological properties and carbon storage of three young Technosols deriving from volcanic soil of Campi Flegrei, Italy, were compared with two natural volcanic soils, sampled from two forest ecosystem sites (chestnut and Mediterranean maquis). The soil properties were examined with Vis-NIR spectroscopy and portable XRF, along the soil profile. The results showed that the average soil organic matter (SOM) amount in Technosols profiles were lower than in natural volcanic soils. The differences in SOM content between the two investigated natural volcanic soils probably resulted from their land-use histories and different plant cover. Indeed, the chestnut soil profile, which has a higher SOM content, was covered by an old chestnut grove, while the second soil profile, after a severe burning, showed a change in natural Oak forest vegetation towards the typical Mediterranean maquis. The microbial biomass can be predicted with Vis-NIR spectroscopy coupled with PLS Regression. Our results showed that 6-year natural incorporation of organic residue in Technosols significantly increased the C storage on the top soils due to the increase in C input with rhizodeposition. The forest soils show higher TOC content also with the depth that indicate a greater capacity of C storage in response to litter incorporation, whereas the Technosols accumulated about half the amount of TOC, compared to the chestnut grove. Indeed, after six years of natural vegetation, the Technosols showed a large potential to sequester C and to sustain biological activity. Overall, the emerging knowledge on Technosols make them highly promising for the regeneration of urban area. [ABSTRACT FROM AUTHOR]