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The implementation of organic amendments, such as biochar and compost, can be an effective and innovative environmental friendly option for the recovery of functionality of soils contaminated by potentially toxic elements (PTE). The aim of this study was therefore to assess the influence of a biochar added at 3% w/w (Bio) and its combination with a municipal solid waste compost (MSWC), on the mobility, bioavailability, and phytotoxicity of several (PTE), As (55 mg·kg−1), Sb (84 mg·kg−1), Ni (176 mg·kg−1) and Cr (214 mg·kg−1) present in a contaminated soil (TS). Sequential extraction procedures showed that biochar and its combination with MSWC decreased soil labile PTE, with biochar increasing remarkably their residual fraction compared to TS-soil (+47, 59, 4, and 9% for As, Sb, Cr, and Ni respectively). Amendment addition also favored an increase of the metabolic potential and catabolic versatility of soil microbial communities, as well as soil functionality. Dehydrogenase, β-glucosidase, and urease activities in TS+Bio showed a significant increase (+45, 16, and 21% respectively) with respect to control. Results from a pot experiment showed that all treatments increased the plant yields significantly in the order: Bio>Bio-MSWC>TS (e.g. the shoot length of green bell pepper and wheat grown on Bio increased, respectively, by a factor of 1.8 and 1.2 compared to TS plants). The amendments addition also reduced PTE transfer from root to shoot. Overall, the results obtained indicated that biochar addition at 3% can be an effective environmental friendly strategy for the in situ stabilization of PTE in polluted soils.

The suitability for aided phytoremediation of Cynara cardunculus L. var. altilis and municipal solid waste compost (MSWC) applied at 2% and 4 % rates was evaluated in a multi potentially toxic element (PTE)-contaminated mining soil (Pb ~ 15,383 mg kg−1, Zn ~ 4076 mg kg−1, As ~ 49 mg kg−1, Cd ~ 67 mg kg−1, Cu ~ 181 mg kg−1, and Sb ~ 109 mg kg−1). The growth of C. cardunculus significantly increased with compost amendment and followed the order: MSWC-4% > MSWC-2% > Control. PTE concentrations in the roots of plants grown on amended soils decreased compared with control plants (i.e., less than ~ 82, 94, and 88% for Pb, Zn, and Cd respectively). PTE translocation from roots to shoots depended on both PTE and amendment rate but values were generally low (i.e., < 1). However, PTE mineralomasses were always higher for plants grown on MSWC-amended soils because of their higher biomass production, which favored an overall PTE bioaccumulation in roots and shoots. After plant growth, labile As and Sb increased in amended soils, while labile Pb, Zn, Cu, and Cd significantly decreased. Likewise, dehydrogenase and urease activities increased significantly in planted soils amended with MSWC. Also, the potential metabolic activity and the catabolic versatility of soil microbial communities significantly increased in planted soils amended with MSWC. Overall, our results indicate that C. cardunculus and MSWC can be effective resources for the aided phytoremediation of multi PTE-contaminated soils.

Pseudoaneurysm of mitral-aortic intervalvular fibrosa (P-MAIVF) is a rare acquired malformation of the mitral-aortic intervalvular area. It appears as a pulsatile cavity in the mitral-aortic junction communicating with the left ventricular outflow tract. P-MAIVF has been reported as a complication of aortic and mitral valve surgery, infective endocarditis, and thoracic trauma. It is associated with life-threatening complications. The recommended treatment is surgery, however, conservative therapy is an alternative approach for high-risk patients or when surgical treatment is refused. We describe a successfully exclusion of a P-MAIVF by transapical transcatheter aortic valve implantation in a patient with concomitant severe aortic stenosis.

In this study, the effectiveness of softwood-derived biochar (BC) in the retention of potentially toxic elements (PTE, i.e., Cu(II), Pb(II), As(V), and Sb(V)) was evaluated at different pH values (4.5, 6.0, and 7.0), along with its capacity to alleviate PTE phytotoxicity. At all pH values, sorption and kinetic isotherms followed the trend: Pb(II) (e.g., ~ 0.56 mmol g−1at pH 6.0) > Cu(II) (e.g., ~ 0.33 mmol g−1at pH 6.0) > As(V) (e.g., ~ 0.29 mmol g−1at pH 6.0) > Sb(V) (e.g. ~ 0.24 mmol g−1at pH 6.0). Kinetic data strongly correlated with the pseudo-second-order kinetic equation; Langmuir and Freundlich isotherm models suggested monolayer sorption of Cu(II), Pb(II), and As(V) onto the BC surface and the interaction of Sb(V) with BC sites characterized by distinct sorption energy (i.e., multilayer sorption). Scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) analysis of PTE-saturated BC showed that Pb(II) was mainly associated with O, Sb(V) with Ca and Fe, while Cu(II) and As(V) with Fe and O. This suggested that hydroxyl and carboxyl functional groups, amorphous Fe oxy-hydroxides, as well as PTE precipitation with BC components were likely responsible for BC sorption capacity. Treatment of PTE-saturated BC with Ca(NO3)2and a range of environmentally relevant organic acids indicated that 6–11% of PTE were loosely bound and easily exchangeable, while up to 60% could be mobilized by the organic acids. Hydroponic plant-growth experiments using triticale plants showed that BC stimulated plant growth in the presence of PTE and reduced their phytotoxicity.

A 73-year-old patient, on chronic anticoagulation therapy (Acenocoumarol), was admitted for recurrent haemoptysis since one week. He had a past surgical history of repaired congenital aortic coarct...

Organic based amendments can be used to reduce metal(loid)s mobility in polluted soils and alleviate possible toxicity phenomena towards soil microbiota. Therefore, the objectives of this study were to evaluate the influence of municipal solid waste compost (MSWC) on the mobility of metal(loid)s in different contaminated soils and to determine the amendment effect on selected soil biochemical and microbial features. To this aim, MSWC was added at two rates (1 and 3% w/w) to different soils sampled in distinct regions of Lebanon (Halba and Terbol, i.e. HS and TS respectively) polluted with metal(loid)s such as As (total concentrations between 31 and 54 mg·kg−1) and Sb (between 93 and 120 mg·kg−1), and trace metals such as Ni, Cr and Zn. After two months of soil-amendment contact, compost addition at both rates significantly increased the non-extractable fractions of As, Sb, Ni, Cr and Zn (e.g. +25% of residual Sb in TS-MSWC 3% with respect to untreated TS), while decreased the environmentally-relevant water soluble and exchangeable fractions of all the metal(loid)s. This effect was more relevant for both soils when 3% MSWC was applied. The amendment addition similarly affected the community level physiological profile (Biolog CLPP) of the respective soil culturable microbial communities, which however showed an opposite trend in the two soils. In particular, compost addition increased the metabolic potential and catabolic versatility of the HS microbial community (compared to the untreated control), while the same proxies were significantly reduced in the amended TS soil. Differently, soil dehydrogenase (DHG), β-glucosidase (β-GLU) and urease (URE) activities were significantly enhanced in both soils treated with compost (e.g. + 17, 45 and 27% for DHG, URE and β-GLU in TS-MSWC 3% with respect to untreated TS). The results obtained showed that the addition of MSWC, particularly at the 3% rate, was effective at fixing the metal(loid)s present in both soils, had a substantial influence on the structure of the soil microbial communities and a positive effect on soil functionality. Taken together the results presented suggest that MSWC can be used as an alternative and environmental friendly amendment for the in situ remediation of metal(loid)s-polluted soils.

Soil microbial communities (SMCs) are important drivers of forest ecosystem functions and services. To optimize afforestation practices, it is important to understand how pure and mixed plantations can affect SMCs and their functioning. Therefore, the objective of this work was to investigate the SMC structure and function of six Mediterranean woody species grown as monocultures, and of six selected 1:1 combinations. SMC structure was assessed through the abundance estimation of different culturable heterotrophic microbial populations (i.e. bacteria, fungi, actinomycetes, Pseudomoas spp. and aerobic spore-forming bacteria) and the Biolog community level physiological profile, while soil biochemical functioning was estimated by quantifying soil dehydrogenase (DHG) activity. Species richness (SR) did not increase the abundance of culturable heterotrophic microbial populations, nor the number of carbon sources metabolized by the microbial communities (Biolog richness) or DHG activity. However, SR significantly decreased the potential metabolic activity (Biolog AWCD) of soil microbial populations. Leaf type significantly affected soil microbial and biochemical features, particularly for monocultures where conifer plots were characterized by a significantly higher fungal/bacterial ratio, reduced AWCD and richness as well as reduced DHG values. Significant interactions between tree species in mixed plots were noticed as well as significant correlations between plant community weighted mean (CWM) traits and soil microbial and biochemical features. Both SMC structure and function were clearly influenced by tree plantations and, importantly, microbial populations of monocultures and mixed plantations, and their functioning, were governed by different CWM traits.

In this study, we investigated the Sb(V) adsorption on ferrihydrite (Fh) at different pH values, in the presence and absence of common competing anions in soil such as phosphate (P(V)) and arsenate (As(V)). Batch adsorption experiments, carried out at pH 4.5, 6.0, and 7.0, showed a greater affinity of Fh towards P(V) and As(V) with respect to Sb(V), especially at higher pH values, while the opposite was true at acidic pH. The capacity of Fh to accumulate greater amounts of phosphate and arsenate in the 6.0–7.0 pH range was mainly linked to the different acid properties of P(V), As(V), and Sb(V) oxyanions. The Sb(V) adsorption on Fh was highly pH-dependent and followed the following order: pH 4.5 (0.957 mmol·g−1 Fh) > pH 6.0 (0.701 mmol·g−1 Fh) > pH 7.0 (0.583 mmol·g−1 Fh). Desorption of antimonate from Sb(V)-saturated Fh, treated with citric and malic acid solutions, was ~equal to 55, 68, and 76% of that sorbed at pH 4.5, 6.0, and 7.0, respectively, while phosphate, arsenate, and sulfate were able to release significantly lower Sb(V) amounts. The FT-IR spectra revealed substantial absorbance shifts related to the surface hydroxyl groups of Fh, which were attributed to the formation of Fe-O-Sb(V) bonds and supported the formation of inner-sphere bonding between Sb(V) and Fh.

In this study, the role of lead [Pb(II)] in the sorption of arsenate [As(V)] by a Ca-polygalacturonate network (CaPGA), i.e. a model of root mucilage, was determined in acidic conditions (pH 4.5) c...

This study evaluated the influence of a municipal solid waste compost (MSWC) and monocalcium phosphate (MCP), alone or combined, on the mobility, toxicity, bioavailability and health risk of fluoride (1000 mg F

This study aimed to evaluate the influence of Eisenia fetida (Savigny), added to an acidic soil contaminated with potentially toxic elements (PTEs; As, Sb, Cd, Pb, Zn) and amended with a softwood-derived biochar (2 and 5% w/w), on the mobility of PTEs and soil health (i.e. nutrient availability, enzyme activity and soil basal respiration). The PTEs bioaccumulation by E. fetida and the acute ecotoxicity effects of the amended soils were also evaluated. The interaction between earthworms and biochar led to a significant increase in soil pH, organic matter, dissolved organic carbon content, cation exchange capacity, and exchangeable Ca compared to the untreated soil. Moreover, the water-soluble and readily exchangeable PTE fraction decreased (with the exception of Sb) between 1.2- and 3.0-fold in the presence of biochar and earthworms. Earthworms, biochar, and their combination, led to a reduction of phosphomonoesterase activity which in soils amended with biochar and earthworms decreased between 2.2- and 2.5-fold with respect to the untreated soil. On the other hand, biochar and earthworms also enhanced soil basal respiration and protease activity. Although the survival rate and the weight loss of E. fetida did not change significantly with the addition of 2% biochar, adding the highest biochar percentage (5%) resulted in a survival rate that was ~2-fold lower and a weight loss that was 2.5-fold higher than the other treatments. The PTE bioaccumulation factors for E. fetida, which were less than 1 for all elements (except Cd), followed the order Cd > As>Zn > Cu > Pb > Sb and were further decreased by biochar addition. Overall, these results highlight that E. fetida and biochar, especially at 2% rate, could be used for the restoration of soil functionality in PTE-polluted environments, reducing at the same time the environmental risks posed by PTEs, at least in the short time.

Background The crescent availability of high-resolution cardiac imaging allows detection of myocardial structural variations. Differentiate these entities from others with different clinical significance can be challenging. Clinicians should be familiar with myocardial clefts to avoid erroneous diagnosis. Case summary A 63-year-old smoker man alerted the emergency medical system for sudden chest pain. The electrocardiogram showed Pardee wave in inferior leads. Coronary angiography evidenced a 100% occlusion of right coronary artery that was treated by angioplasty and drug-eluting stent implantation with optimal angiographic result. At ventriculography, two fissure-like protrusion were observed in the inferior wall. Urgent transthoracic echocardiogram (TTE) demonstrated two deep fissures on the mid-inferior wall, contained by a thin sub-epicardial layer, with sub-total obliteration during systole. A diagnosis of myocardial clefts was suspected and after Heart Team discussion, a conservative strategy was proposed. Early cardiac magnetic resonance (CMR) confirmed two myocardial crypts on the mid-inferior wall. Stability of myocardial fissures and absence of left ventricular remodelling was confirmed by TTE, in a 2 years of follow-up period. Discussion Myocardial cleft should always be considered in the differential diagnosis of myocardial wall defects. In a patient presenting with an acute myocardial infarction, the main differential diagnosis is pseudoaneurysm. In this setting modified TTE views and meticulous analysis of CMR sequences are recommended to confirm the diagnosis and estimate the risk of myocardial rupture.

The effect of long-term ageing (up to 700 days) on the mobility, potential bioavailability and bioaccessibility of antimony (Sb) was investigated in two soils (S1: pH 8.2; S2: pH 4.9) spiked with two Sb concentrations (100 and 1000 mg·kg−1). The Sb mobility decreased with ageing as highlighted by sequential extraction, while its residual fraction significantly increased. The concentration of Sb (CDGT), as determined by diffusive gradients in thin films (DGT), showed a reduction in potential contaminant bioavailability during ageing. The DGT analysis also showed that Sb-CDGT after 700 days ageing was significantly higher in S1–1000 compared to S2–1000, suggesting soil pH plays a key role in Sb potential bioavailability. In-vitro tests also revealed that Sb bioaccessibility (and Hazard Quotient) decreased over time. Linear combination fitting of Sb K-edge XANES derivative spectra showed, as a general trend, an increase in Sb(V) sorption to inorganic oxides with ageing as well as Sb(V) bound to organic matter (e.g. up to 27 and 37% respectively for S2–100). The results indicated that ageing can alleviate Sb ecotoxicity in soil and that the effectiveness of such processes can be increased at acidic pH. However, substantial risks due to Sb mobility, potential bioavailability and bioaccessibility remained in contaminated soils even after 700 days ageing. Refereed/Peer-reviewed

In the context of the coronavirus disease 2019 pandemic, myocardial injury is a relatively frequent finding. Progression to cardiogenic shock has been rarely described, especially in healthy young patients. The underlying mechanisms are to date controversial. A previously healthy 18‐year‐old female teenager affected by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) developed fulminant cardiogenic shock requiring a prompt extracorporeal membrane oxygenation support. Cardiac involvement was predominant compared with the pulmonary one. Myocardial biopsies were performed; and in order to clarify the pathophysiology of the acute heart failure, optical and transmission electron microscopy study was realized. Two additional immunohistology techniques were developed in order to (i) detect a SARS‐CoV‐2 recombinant fusion nucleoprotein by using a specific antibody and (ii) study fractalkine expression induced by activated endothelium because this molecule is well known to be elevated in patients with severe cytokine release syndrome. SARS‐CoV‐2 genome was not detected in the myocardium. Even if the clinical presentation, laboratory markers, and cardiac imaging techniques strongly suggested fulminant myocarditis, histology and immunohistology were not fully consistent with this diagnosis according to the Dallas criteria. Although rare suspected coronavirus particles were found by transmission electron microscopy in the cardiac endothelium, neither significant immunoreactivity for the viral nucleocapsid protein nor image suggestive of endotheliitis was detected. Intense endothelial immunoreactivity pattern for fractalkine expression was observed. From a clinical point of view, the left ventricular systolic function gradually improved, and the patient survived after a long stay in the intensive care unit. Our observations suggest that a massive cytokine storm induced by SARS‐CoV‐2 infection was the main cause of the cardiogenic shock, making a direct viral injury pathway very unlikely.

Softwood-derived biochar (5% w/w) was added to two mining soils (S1 and S2) contaminated with Cd (4.8–74 mg kg−1), Pb (318–1899 mg kg−1) and Zn (622–3803 mg kg−1), to evaluate its immobilization capabilities towards such potentially toxic elements (PTEs). Biochar addition (S + B) increased soil pH, organic carbon content, extractable phosphorous and calcium. Sequential extractions showed that biochar reduced the labile pools of PTEs (e.g. −29, 55 and 79% of water-soluble and exchangeable Cd, Zn and Pb respectively in S1 + B compared to S1) and at the same time increased their most stable and less mobile fractions. Leaching experiments revealed a significant decrease of DOC, N-NO3−, P and PTEs in biochar-treated soils, and an increase of leached K. Kinetic equations derived from leaching data showed that PTEs in control soils were quickly mobilized, while those in biochar-treated soils needed longer time to leachate. In vitro tests showed that biochar was effective at reducing the bioaccessibility of Cd and Pb in the gastric phase of S2 and that of Zn and Pb in the intestinal phase of S1. The results obtained showed that biochar could be used as alternative amendment for the recovery of PTEs-contaminated soils.

This study assessed the suitability of Phragmites australis and Arundo donax for the aided phytostabilization of metal(loid)s in polluted soils treated with an iron-rich water treatment residue (Fe-WTR), a municipal solid waste compost (MSW-C) and their combination (Fe-WTR + MSW-C). The three soils under study (S1, S2, S3) showed very high total concentrations of As (from 371 to 22,661 mg·kg− 1 d.w.) and variable amounts of co-occurring trace metals (TMs) (i.e. Pb, 74–2162; Zn, 57-1535 and Cu, 19–412 mg·kg− 1 d.w.). Results showed that P. australis and A. donax biomass was significantly increased in all the amended soils and followed the order: MSW-C > Fe-WTR + MSW-C > Fe-WTR > Control. For both plant species grown in the amended soils, metal(loid)s concentration in below ground organs were higher than those in above ground tissues. In S1 soil (the most polluted and acidic; pH 3.77), the highest As bioaccumulation factors (BAFs) were recorded for plants grown on untreated soil (approx. 45% higher with respect to those recorded for plants in treated soils), where the concentration of labile As was significantly higher with respect to amended soils. By contrast, in S2 and S3 soils, the most effective As bioaccumulator plants were grown on soils treated with compost, even if the addition of this amendment induced a decrease of the soil As extractability. Similar results were detected for TMs in S1 soil, where P. australis and A. donax grown on soil amended with compost showed the highest Pb, Zn and Cu BAFs, while variable results were detected in S2 soil. The lowest As translocation factors (TFs ≪ 1.0) were detected for plants grown on compost-amended soils (25 and 51, 34 and 50, 64 and 55% lower with respect to P. australis and A. donax control plants in S1, S2 and S3 soils respectively), while TMs translocation from roots to shoots was more variable and depending on soil, TMs, amendment and plant species. Overall, our results indicate the suitability of P. australis and A. donax, and of Fe-WTR and MSW-C, for the aided phytostabilization of soils contaminated with arsenic and trace metals.

Antimony (Sb) and its compounds are emerging priority pollutants which pose a serious threat to the environment. The aim of this study was to evaluate the short-term fate of antimonate added to different soils (S1 and S2) with respect to its mobility and impact on soil microbial communities and soil biochemical functioning. To this end, S1 (sandy clay loam, pH 8.2) and S2 (loamy coarse sand, pH 4.9) soils were spiked with 100 and 1000 mg Sb(V) kg−1 soil and left in contact for three months. Sequential extractions carried out after this contact time indicated a higher percentage of labile antimony in the Sb-spiked S1 soils than S2 (e.g. ~13 and 4% in S1 and S2 treated with 1000 mg Sb(V) kg−1 respectively), while the opposite was found for residual (hardly bioavailable) Sb. Also, a reduced number of culturable heterotrophic bacteria was recorded in Sb-spiked S1 soil (compared to the unpolluted S1), while an increased one was found in S2. Heterotrophic fungi followed the opposite trend. Actinomycetes and heat-resistant aerobic bacterial spores showed a variable trend depending on the soil type and Sb(V) treatment. The Biolog community level physiological profile indicated a reduced metabolic activity potential of microbial communities from the Sb-spiked S1 soils (e.g. 2-fold for Sb-1000). The soil dehydrogenase activity followed the same trend. High-throughput 16S rRNA amplicon sequencing analysis revealed that Sb did not influence the bacterial α-diversity in both soils, while significantly affected the composition of the respective soil bacterial communities. Several phyla (e.g. Nitrosospira Nitrososphaeraceae, Adheribacter) were found positively correlated with the concentration of water-soluble Sb in soil. Overall, the results obtained suggest that the risk assessment in soils polluted with antimony should be a priority especially for alkaline soils where the high mobility of the anionic Sb(OH)6ˉ species can pose, at least in the short-term, a serious threat for soil microbial abundance, diversity and functionality, soil fertility and eventually human health. Refereed/Peer-reviewed

The use of organic-based amendments for gentle remediation options (GRO), i.e. the stabilization of trace elements (TE) in polluted soils and the reduction of their impact on soil microbial and biochemical features, has been constantly growing in last 10 years. To verify the effectiveness of biochar and compost in such context, biochar (1 and 3% w/w), compost (3% w/w) and their combination (compost 2% + biochar 2% w/w) were added to two sub-alkaline soils (FS and MS) contaminated with Sb (41–99 mg kg−1 respectively), As (~18 mg kg−1), and trace metals such as Ni (103–172 mg kg−1 respectively) and Cr (165–132 mg kg−1 respectively). Most of the treatments (especially 3% biochar) reduced labile TE pools (water-soluble and exchangeable) and increased their residual (non-extractable) fractions (e.g. +48, 56, 66, and 68% of residual Sb, As, Cr and Ni in MS-treated soil compared to the untreated control). The amendments addition had both stimulating and inhibiting effects on the activity of soil microbial communities, as shown by the Biolog community level physiological profiles. However, in both soils, 3% biochar produced the highest increase of metabolic potential as well as the use of carboxylic acids and polymers by the soil microbial communities. Likewise, soil dehydrogenase (DHG), β-glucosidase (β-GLU) and urease (URE) activities were significantly enhanced in FS and MS soils treated with 3% biochar (e.g. +77, 48, and 17% for DHG, URE and β-GLU in FS-3% biochar with respect to untreated FS). Overall, the results from this study showed that the amendments investigated (particularly 3% biochar) can be effectively used for GRO of sub-alkaline soils, being able to reduce labile TE and to increase the metabolic potential and actual biochemical activities of the respective soil microbial communities. The manifold environmental implications of such effects are discussed.

Assisted phytoremediation, i.e. the combination of amendment and plant cultivation to remove potentially toxic elements (PTE) from soil, or to reduce their mobility and toxicity, can represent an effective gentle remediation option for the recovery of PTE-contaminated soils. The aim of this study was to evaluate the suitability of different grass and legume species, such as Arundo donax L., Hordeum vulgare L. and Lupinus albus L., in assisted phytoremediation programs of PTE-contaminated soils in combination with a municipal solid waste compost (MSWC) used at 2 and 4% rates. The soil was heavily contaminated by different PTE, i.e. Pb (15,383 mg kg − 1 ), Zn (4,076 mg kg − 1 ), Sb (109 mg kg − 1 ), Cd (67 mg kg − 1 ) and As (49 mg kg − 1 ). The selected plant species were able to grow in the contaminated soil, and their biomass production was significantly influenced by the compost either positively (e.g. A. donax) or negatively (e.g. H. vulgare roots). Compost addition significantly decreased or did not influence the PTE uptake and bioaccumulation factors of A. donax and H. vulgare roots and shoots, while it increased those of L. albus (particularly in roots) with respect to As, Sb, Pb and Cu. Finally, MSWC increased the PTE removal efficiency of A. donax (and partially of L. albus but not by H. vulgare), i.e. its ability to bioaccumulate PTE in the below ground organs, especially when grown in soils amended with 4% MSWC. The results indicated that A. donax, and in selected cases L. albus, can be used in combination with MSWC for the phytostabilization of PTE-contaminated soils.

Two different amendments, an iron-rich water treatment residue (Fe-WTR), a municipal solid waste compost (MSW-C) and their combination (Fe-WTR + MSW-C) were added at different rates (from 2 to 4% w/w) to three mining soils (S1, S2, S3) mainly polluted with As (from 371 to 22,661 mg·kg− 1 d.w.) and different co-occurring trace metals (i.e. Pb, Zn and Cu) to evaluate their effectiveness as metal(loid)s-immobilizing agents. After four months of soil-amendment contact, sequential extractions revealed that MSW-C and Fe-WTR induced an increase of the residual As (non-extractable) fraction. Compost was the most effective amendment at increasing the residual As in treated soils (e.g. + 16% in S1-MSW-C with respect to untreated S1), although its addition increased at the same time the exchangeable and water-soluble As fraction and the extractability of Pb, Zn and Cu, especially in S1-MSW-C. Leaching experiments highlighted a similar trend, with the highest cumulative fraction of As leached recorded in S1 and S2 soils amended with MSW-C (3.8 and 1.4-fold higher than respective controls), and the lowest recorded in S1 and S2 soils amended with Fe-WTR (1.2 and 1.8-fold lower than respective controls). On the other hand, Fe-WTR and Fe-WTR + MSW-C were the most effective at reducing the total cumulative concentration of metal (Pb, Zn and Cu) in soil leachate. The results of this study show that the amendments considered influenced with a different extent metal(loid)s mobility, and this was depending on soil and amendment characteristics, as well as the type and amount of contamination.

In this study we evaluated the microbiological and biochemical impact of iron-based water treatment residuals (Fe-WTRs) and municipal solid waste compost (MSWC), alone and combined, on three different soils co-contaminated with arsenic (As) and trace-metals (TM), i.e. Pb, Cu and Zn. Overall, all the amendments considered significantly increased the abundance of culturable heterotrophic bacteria, with MSWC showing the greatest impact across all soils (up to a 24% increase). In most of treated soils this was accompanied by a significant reduction of both the (culturable) fungal/bacterial ratio, and the proportion of culturable As(V)- and As(III)-resistant bacteria with respect to total bacterial population. The catabolic potential and versatility of the resident microbial communities (assessed by community level physiological profile) was highly soil-dependent and substantial increases of both parameters were observed in the amended soils with the higher total As concentration (from approx. 749 to 22,600 mg kg−1). Moreover, both carbon source utilisation profile and 16S rRNA soil metagenome sequencing indicated a significant impact of MSWC and Fe-WTRs on the structure and diversity of soil microbial communities, with Proteobacteria, Actinobacteria and Firmicutes being the most affected taxa. The assessment of selected soil enzyme activities (dehydrogenase, urease and β-glucosidase) indicated an increase of metabolic functioning especially in soils treated with MSWC (e.g. dehydrogenase activity increased up to 19.5-fold in the most contaminated soil treated with MSWC). Finally, the microbial and biochemical features of treated (and untreated) contaminated soils (i.e. total bacterial counts, catabolic potential and versatility and soil enzyme activities) were highly correlated with the concentrations of labile As and TM in these latter soils and supported a clear role of the tested amendments (especially MSWC) as As- and TM-immobilising agents.

Summary Iron oxy-hydroxides in soil are known to have a large affinity for arsenate (As(V)) inorganic species. At the soil–root interface such mineral components are embedded by mucilaginous material that is secreted from continuously growing root cap cells. In order to determine the role of plant mucilages in As(V) sorption by iron oxy-hydroxides, we layered a calcium (Ca)-polygalacturonate network (CaPGA) on to amorphous iron (Fe) (III) hydroxide (ferrihydrite, Fh) particles. The scanning electron micrographs of the CaPGA network coating the ferrihydrite (Fh–CaPGA) show a regular structure with a honeycomb-like pattern where interlacing fibrils form a porous system. The FT-IR spectra of Fh–CaPGA suggest that CaPGA fibrils are retained by the surface Fe(III) nuclei of Fh through electrostatic interactions. The sorption experiments carried out at pH 4.3 and 5.8 indicated a smaller amount of As(V) sorbed by Fh–CaPGA than by Fh alone, being less after 3 and 24 hours of reaction by about 70 and 30%, respectively. The sorption of As(V) by Fh was also studied in the presence of caffeic acid (CAF), an important root exudate. Simultaneous sorption kinetics show that As(V) sorption by Fh is almost independent of CAF concentration, indicating a greater affinity of arsenate ions towards the Fh surfaces. However, the amount of As(V) sorbed by the Fh coated by CaPGA, in the presence of 0.25, 0.5 and 1.0 mm CAF, is markedly smaller by about 20, 27 and 40%, respectively, than that found in the As(V)–CAF-Fh ternary systems. This is caused mainly by redox reactions involving CAF and the surface Fe(III) nuclei of Fh leading to the formation of CAF oxidation products which prevent As(V) sorption.

In this study, the ability of two different water treatment residuals (Fe- and Al-WTRs) to accumulate antimony(V) from an aqueous solution was investigated at different pH values (pH 4.5 and 6.5). Both WTRs showed a maximum Sb(V) sorption capacity of approx. 0.22 mmol g−1 at pH 4.5 which declined at pH 6.5, particularly for Fe-WTR (i.e., 0.059 and 0.163 mmol g−1 of Sb(V) sorbed by Fe- and Al-WTRs respectively). The greater capacity of WTRs to accumulate antimonate at pH 4.5 seemed to be linked to their chemical properties, such as the pHPZC and the specific surface area. At both pH values, the Sb(V) sorption by Al- and Fe-WTRs followed a pseudo-second-order kinetic model, while the sorption isotherms data fitted the Freundlich model better than the Langmuir one, suggesting the presence of heterogeneous Sb(V) adsorption sites. The sequential extraction of WTR-Sb(V) systems showed that a significant amount of Sb(V) was retained by WTRs through chemical interactions, i.e., through the formation of inner sphere surface complexes [e.g., Fe/Al–O–Sb(V)]). This was particularly relevant at higher pH values (pH 6.5) where more than 60 and 50% of the Sb(V) sorbed by Fe- and Al-WTRs respectively was retained by specific chemical bonding. The residual Sb(V) was higher for the Al-WTR at both pH values, and the highest amount of residual Sb(V) was recorded at pH 4.5 [> 65% of the total Sb(V) sorbed]. SEM-EDX analysis of the WTR-Sb(V) systems showed that antimony was mainly associated with Fe and Al, thus supporting the Sb(V) affinity for Al/Fe oxy-hydroxides. Treatment of WTR-Sb(V) systems with citric and malic acids, at concentrations relevant in the rhizosphere, indicated that Sb(V) could be released by both acids, with 4.5 mM citric acid favoring the highest Sb(V) release in both WTRs. The results from this study suggest that WTRs could be used as alternative amendments for the in situ immobilization of Sb(V) in acidic or circumneutral polluted soils.

In this study, we investigated the cooperative effect of caffeic (CAF) and malic (MAL) acids as well as the role of polygalacturonic acid (PGA) on the toxicity of copper (Cu)(II) towards triticale plants (× Triticosecale Wittm.). Plant growth experiments carried out in hydroponic solutions at pH 6.0 revealed that CAF and PGA, but not MAL, were quite effective at reducing Cu(II) phytotoxicity and that MAL addition abolished the positive effects of CAF. The study of the CAF-Cu(II) system in aqueous solution clearly indicated that the lower toxicity of Cu(II) in the presence of CAF was due to the occurrence of a redox reaction between CAF and Cu(II), while the phytotoxicity recorded in the Cu(II)-CAF-MAL system was attributed to a competitive effect of MAL in the Cu(II) complexation by CAF, which ultimately reduced the redox activity. The lowest Cu(II) phytotoxicity recorded in the presence of PGA was attributed to the high affinity of the polysaccharidic matrix towards the metal ion. The results from this study shed new light on the Cu(II)-detoxifying action of selected root exudates and highlight the negative cooperation of MAL on the Cu(II)-detoxifying activity by CAF.

The ability of two municipal solid waste composts (MSW-Cs) to sorb antimony(V) in acidic conditions (pH 4.5) was investigated. Sorption isotherms and kinetics showed that both MSW-Cs could sorb antimony(V), even if in different amounts (~ 0.18 and 0.24 mmol g−1 of Sb(V) by MSW-C1 and MSW-C2, respectively). These differences were ascribed to the chemical composition of composts, as well as to the total acidity of their humic substances. The Sb(V) sorption by both MSW-Cs followed a pseudo-second-order kinetic model, while the sorption isotherms data fitted the Freundlich model better than the Langmuir one. The humic acids extracted from composts contributed to 4.26 and 8.24% of Sb(V) sorption by MSW-C1 and MSW-C2 respectively. SEM-EDX spectra of the MSW-C+Sb(V) systems showed a certain association of Ca(II) with Sb(V), while sequential extraction procedures indicated that more than 80% of the Sb(V) sorbed was strongly retained by MSW-Cs. On the other hand, treatment with oxalic acid at pH 4.5 favored the release of more than 98 and 65% of the Sb(V) sorbed by MSW-C1 and MSW-C2 respectively, supporting a possible role of calcium in Sb(V) retention. The results from this study suggest that MSW-Cs could be used as amendments for the in-situ immobilization of Sb(V) in acidic-polluted soils.

Four iron and aluminium-based products, including red mud (RM), hematite (Fe 2 O 3 ), an iron-rich water treatment residual (Fe-WTR) and amorphous Al hydroxide (Al-OH), were evaluated for their effectiveness at stabilising As and heavy metals (i.e. Cd, Cu, Pb, Zn) in a circumneutral contaminated soil [As (2105 mg kg −1 ), Cd (18 mg kg −1 ), Cu (264 mg kg −1 ), Pb (710 mg kg −1 ), Zn (522 mg kg −1 )]. Treatment impacts on soil microbial and biochemical features (i.e. microbial biomass-C, microbial counts, 16S rRNA PCR-TTGE of culturable bacteria, dehydrogenase, urease and β-glucosidase activity, Biolog derived parameters-AWCD and richness) as well as bean ( Phaseolus vulgaris ) and wheat ( Triticum vulgare ) growth were also assessed. After 6 months equilibration, all the amendments (application rate 3% w/w) but RM reduced labile As while only Al-OH reduced the concentration of water-soluble heavy metals. Despite the highest bioavailability of contaminants, most of the soil microbial and biochemical features monitored (i.e. microbial biomass-C, total bacterial counts, dehydrogenase activity and AWCD) were significantly higher in the RM-soil. Bean germination was completely inhibited in RM-soil while wheat growth was similar to that of the control. The Al-OH treatment was best overall, promoting microbial abundance, diversity and activity while increasing bean and wheat growth and reducing As accumulated in plant shoots. Results suggest that Al-OH is a suitable candidate for field evaluations while the use of RM in the remediation of circumneutral or subalkaline contaminated soils should be reconsidered.

Two strains of Gram-stain-negative, rod-shaped bacteria were isolated from root nodules of the South African legume Rhynchosia ferulifolia and authenticated on this host. Based on phylogenetic analysis of the 16S rRNA gene, strains WSM3930 and WSM3937T belonged to the genus Burkholderia , with the highest degree of sequence similarity to Burkholderia terricola (98.84 %). Additionally, the housekeeping genes gyrB and recA were analysed since 16S rRNA gene sequences are highly similar between closely related species of the genus Burkholderia . The results obtained for both housekeeping genes, gyrB and recA, showed the highest degree of sequence similarity of the novel strains towards Burkholderia caledonica LMG 19076T (94.2 % and 94.5 %, respectively). Chemotaxonomic data, including fatty acid profiles and respiratory quinone data supported the assignment of strains WSM3930 and WSM3937T to the genus Burkholderia . DNA–DNA hybridizations, and physiological and biochemical tests allowed genotypic and phenotypic differentiation of strains WSM3930 and WSM3937T from the most closely related species of the genus Burkholderia with validly published names. We conclude, therefore, that these strains represent a novel species for which the name Burkholderia rhynchosiae sp. nov. is proposed, with strain WSM3937T ( = LMG 27174T = HAMBI 3354T) as the type strain.

The mobility and bioavailability of As in the soil-plant system can be affected by a number of organic acids that originate from the activity of plants and microorganisms. In this study we evaluated the ability of citrate and malate anions to mobilize As in a polluted subacidic soil (UP soil) treated with red mud (RM soil). Both anions promoted the mobilization of As from UP and RM soils, with citrate being more effective than malate. The RM treatment induced a greater mobility of As. The amounts of As released in RM and UP soils treated with 3.0 mmol L citric acid solution were 2.78 and 1.83 μmol g respectively, whereas an amount equal to 1.73 and 1.06 μmol g was found after the treatment with a 3.0 mmol L malic acid solution. The release of As in both soils increased with increasing concentration of organic acids, and the co-release of Al and Fe in solution also increased. The sequential extraction showed that Fe/Al (oxi)hydroxides in RM were the main phases involved in As binding in RM soil. Two possible mechanisms could be responsible for As solubilization: (i) competition of the organic anions for As adsorption sites and (ii) partial dissolution of the adsorbents (e.g., dissolution of iron and aluminum oxi-hydroxides) induced by citrate or malate and formation of complexes between dissolved Fe and Al and organic anions. This is the first report on the effect of malate and citrate on the As mobility in a polluted soil treated with RM.

Iron-rich water treatment residues (Fe-WTRs) and municipal solid waste compost (MSWC) were added together at two different total rates (i.e. 0.5% Fe-WTRs+0.5% MSWC and 1% Fe-WTRs+1% MSWC) to a degraded sub-alkaline soil (pH 8.0) contaminated with Sb (∼110 mg kg−1 soil), Pb (∼1200 mg kg−1), Cd (∼23 mg kg−1), and Zn (∼5400 mg kg−1). A large number of chemical and biological endpoints were evaluated to assess the efficacy of the treatments after five months of incubation. Both treatments significantly reduced the labile fractions of the metal(loid)s in soil, especially Sb, while increasing the abundance of culturable heterotrophic bacteria, actinomycetes and fungi (i.e. up to 6.3-, 1.6- and 4.1-fold higher than control respectively). Soil enzyme activities, i.e. dehydrogenase, β-glucosidase and urease, were also significantly enhanced in the treated soils (i.e. up to ∼12-, 3- and 2-fold higher than control respectively). The amendment addition affected the structure of the soil microbial community as highlighted by the higher metabolic potential and catabolic versatility of treated soils (Biolog CLPP) and by the significantly higher α-diversity values based on high throughput partial 16S rRNA gene sequencing. Moreover, analysis of the dominant operational taxonomic units (OTUs) showed differences in the microbial communities of untreated and treated soils. Plant growth (Helichrysum italicum) in the treated soils was greatly stimulated while metal(loid)s uptake was significantly reduced. Overall, the results indicated that the applied treatment could be ideal for the chemical and (micro)biological recovery of sub-alkaline soils contaminated with Sb and co-occurring metals, and H. italicum appears to be a promising plant species for aided phytostabilisation of such soils. Refereed/Peer-reviewed

In this study, the ability of two municipal solid waste composts to adsorb Pb, Cu, Cd and Zn ions (Me(II)) from aqueous solutions was investigated. Sorption experiments, carried out at pH 4.5 to simulate acidic Me(II)-polluted environments, showed for both composts higher affinity for Pb (∼0.45 mmol · g−1) and Cu (∼0.31 mmol · g−1) compared to Cd (∼0.25 mmol · g−1) and Zn (∼0.10 mmol · g−1). The sorption isotherms data fitted the Freundlich model better than the Langmuir in both composts, suggesting the presence of heterogeneous Me(II) adsorption sites. The humic acids (HA) extracted from composts contributed to 16, 23, 17 and 20% in the sorption of Pb, Cu, Cd and Zn, respectively, while the compost water-soluble-fractions hardly affected the sorption/precipitation of the Me(II) ( 65% of the respective total amounts sorbed) while most of Cu and Pb (40 and 54, %) was strongly complexed and/or precipitated. The treatment of the Me(II)-composts with citric and malic acids favored the release of >78 and 48% of Zn, 65 and 30% of Cu and 40 and 30% of Cd, sorbed by both composts, respectively. This release was lower for Pb (

Changes of pasture communities consequent to management practices resulting from land abandonment considerably affect the structure and function of the ecosystem. This study analyses the consequences of grazing abandonment in terms of plant and soil microbial diversity and fertility, on a Mediterranean upland sheep pasture, over a short period (five years). Grazing was experimentally excluded by fencing ten 10×10 m permanent plots within an area that had supported grazing until 2000, by 0.23 sheep ha−1. Plant and soil microbial communities and physicochemical parameters were monitored within the fenced and unfenced control plots, during three sampling times from 2000 (before the fencing) to 2005. Grazing cessation notably altered the floral composition, with an average dissimilarity of 96.7% between the vegetation communities, over five years. No significant change occurred in the control plots that were grazed throughout the sampling period. This work highlighted that, over a short term, the structural change in the specific plant composition affected only the grass species, confirming that grazing favours the small-sized species over the annual species. Further, it was evident that species groups of conservational and phytogeographic interest, like the endemic and Mediterranean-Atlantic species, tended to disappear with pasture abandonment and were substituted by more widespread species throughout the Mediterranean or even the world. Pasture abandonment was accompanied by an increase of soil pH and a decrease in soil organic matter and soil nitrogen. The microbial parameters recorded at three different sampling times revealed a substantial effect of the plant community, or the time of grazing abandonment, on soil microbial abundance and diversity. Considerable importance is given to the consequences of pasture abandonment on the conservation of plant and microbial diversity and on soil fertility.

In the present work we investigated the interactions established between red mud (RM) and phosphate anions (P) at pH 4.0, 7.0 and 10.0. The amount of P sorbed by RM (P-RM) increased as the pH decreased being equal to 4.871 mmol g(-1) at pH 4.0, 0.924 mmol g(-1) at pH 7.0, and 0.266 mmol g(-1) at pH 10.0. Sequential extractions' data of P-RM equilibrated at pH 4.0 and 7.0, suggested that the phosphate sorption at these pH values was mainly regulated by two different mechanisms that gave rise to a chemical adsorption on RM phases, and to the formation of metal phosphate precipitates. By contrast, at pH 10.0 the P-sorption was regulated by a chemisorption mechanism on Fe-Al phases of RM. These findings were supported by FT-IR analysis, which showed a broad band at 1114 and 1105 cm(-1) in P-RM spectra at pH 4.0 and 7.0 respectively, attributable to P-O(H) stretching nu(3)-modes associated to inner-sphere complexes of phosphate on Fe-Al phases, or alternatively to stretching vibrations of PO(4)(3-) tetrahedra, arising from a precipitate of aluminium phosphate. Importantly, the FT-IR spectroscopy showed a phosphate-promoted dissolution of tectosilicates, notably cancrinite and sodalite, in RM exchanged with phosphate at pH 4.0 and 7.0.

In this paper we evaluated the effects of various amendments, notably zeolite, red mud (a by-product of aluminium manufacturing) and lime on decreasing the bioavailability and phytotoxicity of Pb, Cd and Zn present in a contaminated acidic soil (pH = 4.2). Pisum sativum and Triticum vulgare were grown in a glasshouse experiment on untreated-polluted (control) and amended soils and their yield and metal uptake determined. The influence of plants on the total concentration and mobility of Pb, Cd, and Zn, and on several soil microbiological and biochemical parameters was also evaluated and compared to unplanted (control and amended) soils on which we have previously reported. All the amendments enhanced plant yields significantly. Red mud and lime decreased Zn, Pb and Cd availability to plants, whilst zeolite was efficient only at blocking Pb. Red mud in particular decreased heavy metal uptake of pea and wheat by 60–34% (Pb), 79–80% (Cd), and 93–64% (Zn) respectively when compared to the control plants. After plant growth, Cd and Zn solubility in the amended soils was significantly higher than in respective unplanted soils. Likewise, the number of fast-growing heterotrophic bacteria and fungi was higher after pea and wheat compared to bare soil, and this was irrespective of the treatment applied. These data together with Biolog-derived parameters (AWCD and richness) and enzyme activities (dehydrogenase, urease and β-glucosidase) also suggested that pea rhizodeposits, in the different soils, were either more abundant or more readily-available to soil bacterial communities compared to wheat rhizodeposits.

We investigated the taxonomic position and symbiotic capabilities of two root-nodule bacterial strains isolated from the South African herbaceous, papilionoid legume Rhynchosia ferulifolia. The 16S rRNA gene sequence of the two strains was determined along with intragenic sequences of nodA and nifH, together with their symbiotic capabilities when inoculated onto the papilionoid legumes R. ferulifolia, Rhynchosia caribaea, Rhynchosia minima and Macroptilium atropurpureum (Siratro). Burkholderia phymatum STM815T, Cupriavidus taiwanensis LMG 19424T and root-nodule bacteria isolated from R. minima and Rhynchosia totta were included in the study. Root-nodule bacteria isolated from R. ferulifolia, WSM3937 and WSM3930, belong to the genus Burkholderia and are most closely related to Burkholderia terricola (98.8% similarity). The phylogenetic analysis of nodA and nifH revealed substantial similarity of the novel strains with Burkholderia tuberum STM678T, a β-rhizobium also originated from South Africa, and only a distant relationship with South American Mimosa-nodulating β-rhizobia. R. ferulifolia was effectively nodulated only by Burkholderia sp. WSM3937 and WSM3930 and not by bradyrhizobia isolated from Rhynchosia minima and Rhynchosia totta or STM815 and LMG 19924. Nodules induced by the novel strains were determinate and hosted well organized symbiosomes within infected cells. In this study we describe a new symbiotic N-fixing relationship between Burkholderia sp. and the South African legume R. ferulifolia. This is the first report of N-fixation between β-rhizobia and an herbaceous, papilionoid legume from which the strains were originally isolated. The level of N-fixation in this symbiosis approached that achieved by effectively nodulated Medicago sativa and suggests that the β-rhizobia may have a role in N-fixation in agricultural systems.

In this work the dynamics of biochemical (enzymatic activities) and chemical (water-soluble fraction) parameters during 100 days of municipal solid wastes composting were studied to evaluate their suitability as tools for compost characterization. The hydrolase (protease, urease, cellulase, beta-glucosidase) and dehydrogenase activities were characterized by significant changes during the first 2 weeks of composting, because of the increase of easily decomposable organic compounds. After the 4th week a "maturation phase" was identified in which the enzymatic activities tended to gently decrease, suggesting the stabilisation of organic matter. Also the water-soluble fractions (water-soluble carbon, nitrogen, carbohydrates and phenols), which are involved in many degradation processes, showed major fluctuations during the first month of composting. The results obtained showed that the hydrolytic activities and the water-soluble fractions did not vary statistically during the last month of composting. Significant correlations between the enzymatic activities, as well as between enzyme activities and water-soluble fractions, were also highlighted. These results highlight the suitability of both enzymatic activities and water soluble fractions as suitable indicators of the state and evolution of the organic matter during composting. However, since in the literature the amount of each activity or fraction at the end of composting depends on the raw material used for composting, single point determinations appear inadequate for compost characterization. This emphasizes the importance of the characterization of the dynamics of enzymatic activities and water-soluble fractions during the process.