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Future long-term space missions beyond Low Earth Orbit (e.g., to Mars) depend on the development of bioregenerative life support systems able to produce food crops based on in situ resource utilization. Mars regolith potentially contains most of the essential nutrients for plant growth, except for organic matter (OM). Several strategies and treatments can be applied to improve nutrient deficiency of simulants and enhance their performance as plant growth substrates. Although Mars regolith simulants have been characterized by mineralogical, physico-chemical and hydraulic properties, no data are available to date in the scientific literature about the stabilization of exogeneous OM by minerals, including iron (Fe) oxides, over time.This study aims at understanding the mineral transformation and OM turnover in the early stages of terraforming. The Mojave Mars Simulant MMS-1, alone (R100) and with a commercial compost 70:30 v:v (R70C30), was compared to a fluvial sand, alone and with compost (S100 and S70C30). Potato was grown on these substrates for 99 days in greenhouse. Samples were fractionated, obtaining particulate OM (POM) and mineral associated OM (MAOM), andcharacterized for total nitrogen and organic carbon (OC), total element concentration (ICP-OES) and by Fe K-edge X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS).In the whole medium, OC increased in S70C30 (10×) and R70C30 (25×). As expected, most of the OC accumulated in the POM fraction of both growing media (10× in S70C30 and 20× in R70C30), while OC in the MAOM was 3-times higher in R70C30 than in S70C30. Chlorite, smectite and goethite were the main Fe species in S100, according to XANES, while Fe(III)-OM was found in both fractions of S70C30. Moreover, according to EXAFS, hematite occurred in POM, whereas goethite in MAOM. XANES revealed the occurrence of smectite, maghemite and ferrihydrite in R100, and of nontronite and hematite in the MAOM and POM, respectively.Revealing Fe species involved in the formation of organo-mineral interactions will help to identify the main critical aspects and future challenges related to sustainable space farming improving the in-situ use of Martian resources.

The in-situ resource utilisation (ISRU), in terms of native rocky materials and astronaut wastes, is crucial in contests of soil-based space-farming. Nevertheless, extra-terrestrial soils are very different from Earth soils, lacking any form of organic carbon and associated macro and micronutrients. In this research, we aimed to study and modify two commercially available Lunar and Martian regolith simulants (LHS-1 from Exolith Lab and MMS-1 from Martian Garden) to make them an adequate medium for plant growth. Lettuce was chosen as reference crop to guide the discussion on the results obtained. To reach this main objective, we added to simulants a commercially available monogastric-based organic manure chosen as a substitute of a possible organic amendment produced onboard. The simulant/manure mixture rates were 100:0, 90:10, 70:30, 50:50; w:w. As expected, an approximately linear increase of total and bioavailable contents of macro (N, S, P, Ca, K, Mg) and micro (Fe, Mn, Cu, Zn) nutrients with increasing manure addition to simulants was observed. On the other hand, the very high pH of manure (pH, 9.02) along with its salinity (EC, 6.7 dS m−1) and sodicity (Na, 5.3 g kg−1), did not correct the already high pH of simulants (very high for LHS-1), but rather raised their soluble salt content and sodium amount on the exchange complex. In addition, an increase of toxic soluble aluminium and heavy elements (Pb, Ni, Cr, V) was observed, mainly in the strongly alkaline lunar simulant/manure mixtures. The addition of an organic source also produced a generalised improvement of water retention and hydraulic conductivity of both regolith simulants, in proportion to the percentage of manure addiction. For both situations, the best mixture ratio was 70:30. In terms of water retained, the LHS-1 mixtures benefited more than the MMS-1 ones by manure addition since water was held more in the “dry” (between −100 and −600 cm of matric potential head) than in the “humid” (between −25 and −100 cm of matric potential head) region of water retention. This would make LHS-1 mixtures more useful for cultivation of lettuce, at least in terms of physico-hydraulic properties. Nevertheless, the overall characterisation of the mixtures unveiled that MMS-1-based substrates can ensure better agronomic performances than LHS-1 ones, mainly due to lower pHs and higher nutrient availability; this divergent fertility was particularly evident at 90:10 simulant/manure rate and tend to be mitigated by increasing the levels of manure.

The occurrence and bioaccessibility of potentially toxic elements (PTEs) in soils and sediments are investigated by many studies, especially in territories exploited by mining and ore-processing activities, nearby agriculture-driven rural cities. Accordingly, the present study aimed at evaluating the geochemical properties, potential bioavailability, and risks for environment and human health of the most concerning PTEs of study area (Gafsa mining basin, Tunisia) such as Cd, Cr, and Zn in selected soil, sediment, and mining waste samples. The extraction of these solid matrixes by modified EU-BCR sequential extraction revealed that the most easily extractable fractions of each PTE were very low (first 2 steps

Commercialization of seafood industry has led to better accessibility of seafood around the globe and is an important part of global food chain to ensure food requirements worldwide. It forms one of the most complex international food chains and this makes it particularly vulnerable to fraud. In Europe, species substitution and origin mislabelling are the most common frauds faced by the seafood industry. Europe imports over 75% of its seafood with demand for it rising every year, which further increases chances of fraud and make authentication of seafood difficult. Owing to this complex global scenario, traceability of seafood becomes even more important to protect consumer’s rights and ensure safety in food systems. Origin mislabelling includes concealment of geographical origin of illegally harvested fish species whereas species substitution includes replacement of low-value species for a more expensive one for economic gain. Fish growing in different regions have different composition of fatty acids, elemental and isotopic compounds depending on their surroundings. Same differences occur between different species of fish living in the same region due to their varying feeding habits. These traits are used to identify origin mislabelling and species substitution. Several techniques have been employed to identify fish frauds such as DNA based methods, immunological assays, spectroscopic methods, stable isotopes, trace element analysis, fish microbiome analysis, etc. Multielement and stable isotope analyses and NIR spectroscopy are reliable analytical techniques providing useful information and thus accurate chemometric-based traceability models. Multielement profile can also allow to assess the fish nutritional quality and possible presence of contaminants. Stable isotope analysis of elements such as carbon, oxygen, nitrogen and strontium enables to discriminate fish provenance, natural vs feed-based diet, frozen vs fresh fish. NIR is a non-destructive and cost-effective analytical tool. A combined use of these methodologies to identify the fish fraud can strengthen the traceability models, minimising the occurrence of possible prediction errors.In this context, SUREFISH* PRIMA project aims at deploying innovative solutions to achieve unequivocal traceability of Mediterranean fish products, preventing possible frauds. It gathers 13 partners from Italy, Spain, Tunisia, Egypt, Lebanon and 4 pilot sites fishing/growing and processing the following fish species: anchovy (Engraulis encrasicolus), sardine (Sardina pilchardus), bluefin tuna (Thunnus thynnus), tilapia (Tilapia spp.) and grouper (Epinephelus itajara). In the framework of WP3, we will develop and harmonise multi-element, isotope and NIR based analytical methodologies to trace the provenance of these Mediterranean fish species. Basically, we will analyse fresh or thawed fish meat and additional samples such as fish bones and otoliths, aquaculture feeds and sea or fresh waters. The findings will be gathered in a database useful for comparison with data from literature and other FAO fishing areas. * SUREFISH PRIMA project: Fostering Mediterranean fish ensuring traceability and authenticity, https://surefish.eu/. PRIMA Call 2019 Section 1 - Agro-food Value Chain 2019, Topic 1.3.1.

A sustainable management of urban soil is of paramount importance for the modern cities, thus sustainable programs of urban agriculture are strongly supported by policy-makers to preserve urban soil from anthropic degradation, to enhance its ecosystem functions and services and to produce safe and quality food. Although urban agriculture is already a reality in Naples, it is still lacking of a scientific-based approach aiming to: i) characterise pedo-climatic properties, ii) apply site-specific sustainable management practices, iii) enhance urban food quality; iv) address potential contaminants or pathogenic microorganisms threatening food safety. UrbanSoilGreening* project aims to overcome this lack of scientific-knowledge on urban agriculture in the metropolitan area of Naples. Project activities will cover the major issues related to urban agriculture (i.e., soil degradation and contamination, loss of ecosystem functions, food safety). An operative methodology for sustainable management and protection of urban soil will be developed during 2021 in a couple of green spaces in the metropolitan area of Naples potentially exploitable for agricultural purposes, selected on the basis of factors such as proximity to potential sources of contamination. The urban soils will be characterised to assess their physicochemical properties and identify possible contaminants such as potentially toxic elements (PTEs) and hydrocarbons. In the potentially contaminated soils, the bioavailable and bioaccessible fractions of PTEs will be extracted from soil by standardised analytical procedures. In the absence of soil contamination, the green spaces will be still exploited for food production and agricultural purposes. On the other hand, they will be converted into ornamental or spontaneous low-management gardens. The cultivation techniques would address the general interest of preserving the soil and promoting a sustainable management of sites (e.g. organic farming, synergistic techniques, on-site production of high-quality compost to recycle vegetable waste and promote the circular economy, etc.). The cultivation of uncontaminated green spaces will be done in the spring-summer time, selecting food plant species suitable for local urban horticulture. The greening will aim to create areas accessible to local citizens and associations (cooperating actively with project’s team during plant growing season), with a social function as meeting places for the neighbourhood, suitable for hosting social events and activities. Food quality will be evaluated by morphological and quality parameters and chemical analyses. Near infrared (NIR) spectroscopy will be also applied to rapidly assess food quality with minimum sample processing. The possible presence of PTEs and pathogenic microorganisms (e.g., Clostridium, Escherichia, Listeria and Salmonella genera) in food products will be evaluated to establish their chemical and microbiological safety. Major breakthroughs and achievements will be communicated to main stakeholders in education and public outreach activities and scientific events. At the end of project, guidelines for the sustainable management of urban green spaces producing high-quality and safe food crops will be disseminated as electronic document.* Multidisciplinary study to improve the sustainability of urban soil, to protect its ecosystem functions and services, and to enhance the safety and quality of food from urban agriculture (FRA-202009291319). Programma per il Finanziamento della Ricerca di Ateneo UniNA, call 2020, line A.

In the framework of both characterization plan and sustainable land reclamation, required by the European regulation for contaminated sites, it is fundamental to detail and understand soil processes involved in the dynamics of environmental contamination. Areas affected by potentially toxic elements (PTE) frequently show wide variability of contaminant distribution both in space and in depth. Targeted sampling is meant to reduce the risk of incorrect hazard evaluation, as well as decrease time and cost of this tricky procedure. Therefore, a pedology based multi-scale approach has been tuned and applied to an industrial area inside an automobile-battery recycling plant (operative since 1970) in South of Italy. Field scale investigation, after data fusion of geophysical (EMI), spectrometric (Gamma ray dose rate and XRF elemental content) and penetrometric (cone index data by ultrasonic penetrometer) parameters, enabled to identify 4 main key zones characterized by different intensity of the measured variables. At pedon scale, 6 soil profiles were dug until 2 m of depth in the identified zones and showed presence of massive/no structured soils (thickness ranging from 25 to 85 cm) in which the total Pb content ranged from 1700 and 12000 mg/kg (field measurements by portable XRF). At optical microscopy scale, many discrete particles (larger than 2 mm of diameter), having angular - subangular shape and different color, were identified and preliminary examined by portable XRF spectrometer for a semi-quantitative analysis, in collimator mode, to detect the most PTE enriched fragments; the results showed the presence of several medium (from 0.5 x 1 mm wide), greyish-black particles enriched of S and/or Cl, of some other bigger (1 x 4 mm), very dense (i.e., not porous), anisotropic (black) fragments characterized by higher content of S, Pb, Cl, As and Sn, as a whole incorporated in a mineral matrix lesser enriched of S (11 g/kg), Cl (0.8 g/kg), Pb (0.6 g/kg), As (0.2 g/kg). Detailed analysis at submicroscopic scale with SEM, equipped with EDXRA for quantitative analyses, enabled to discriminate the biggest particles in sub-particles mainly composed of Pb (87-89%) and others combining Pb (72-75%) with Cd (11%) and Sn (11-12%). At molecular scale, the mobility and bioavailability of the most abundant PTE were assessed by standardized single-step (ultrapure water, 1M NH4NO3 and 0.05M EDTA) and sequential (EU-BCR and Wenzel)analytical procedures. Although the extent of Cd contamination was much lower than that of Pb, Cd was more mobile and bioavailable than Pb, mainly due to its different geochemical properties. As well, the bioavailability of Sb in the soil was greater than that of As (anionic contaminants).

The risk assessment of phosphate mining/processing industrial activities on the environment and human health is crucial to properly manage and minimize the risks over time. In this work, we studied the inhalation and dermal bioaccessibility of potentially toxic metals (PTM) in different particle-size fractions of urban soil, sedi- ments and tailings from Gafsa-Metlaoui phosphate mining area, to assess afterwards the non-carcinogenic (NCR) and carcinogenic (CR) risks for the health of local citizens and workers constantly exposed to airborne particulate matter (PM) originating from these sources of contamination. Samples were separated in particle-size fractions by centrifugation and consecutive cycles of sedimentation and decanting. The pseudo-total concentrations and bioaccessible fractions of PTM were extracted by aqua regia and in vitro bioaccessibility tests, respectively. Both sediments and tailings showed higher-than-background concentrations of PTM (mainly Cd, Zn and Cr), with a tendency to accumulate these metals in fine particles (1 and CR > 10− 4), especially for children, can occur if ingestion route is also considered. The findings underline the need for adequate protection of contaminated soil, sediments and mine tailings laying nearby urban agglomerates, to reduce the health risks for inhabitants and workers of Gafsa-Metlaoui mining area.

For the assessment of the environmental and sanitary risks deriving from contamination of agricultural soils, it is crucial to identify and characterize the contaminants and study the soil chemical properties influencing their mobility and bioavailability. This information is essential for the selection of the best site remediation and securing strategy. The study site of this work is agricultural land of 6 ha in the province of Naples (Italy) subject to the past illegal burial of industrial wastes, principally from tanneries. With the aim of identifying the contaminants and assessing their mobility and bioavailability, the soil of the site was characterized for the main chemical and physical properties and for the concentration of potentially toxic elements and hydrocarbons. The readily and potentially bioavailable fractions of the main metal contaminants and their distribution in the soil geochemical fractions were determined by extraction in 1 M of NH4NO3, 0.05 M of ethylenediaminetetraacetic acid (EDTA) pH 7, and European Community Bureau of Reference (EU-BCR) sequential fractionation. Further, the speciation of heavy hydrocarbons and chromium was carried out. The agricultural soil was widely contaminated by chromium, zinc, and heavy hydrocarbons (up to 4487, 1846, and 1800 mg/kg, respectively). In some sub-areas, contaminations by cadmium, lead, and copper (up to 283, 417, and 1183 mg/kg, respectively) were also observed. The chromium was found to be scarcely mobile and bioavailable and was mainly associated with the oxidizable, residual, and reducible fractions of the soil (on average 56%, 25%, and 19% of the total, respectively). However, chromium speciation revealed the presence of a significant amount of highly toxic Cr(VI) (above the legal threshold of 2 mg/kg), despite the low oxidizing power of the soil. Zinc was more mobile and bioavailable than chromium and was mainly distributed among the acetic acid-extractable and reducible fractions of the soil (on average 28% and 47% of the total, respectively). Cadmium was found to be very mobile and bioavailable, and was mainly distributed in the acetic acid-extractable and reducible fractions of the soil (on average 40% and 45% of the total). The speciation of heavy hydrocarbons showed that they consist almost entirely of long-chain aliphatic hydrocarbons, considered not very toxic and immobile. These results suggest that the use of not-edible plant coverage might be the best securing and remediation action for the study site, with the potential to preserve the soil ecosystem services, contain the risk of soil erosion and particle dispersion, and phytoextract the bioavailable metals.

This work aimed to study the effects of compost (applied at two rates) and two commercial microbial biostimulants on the mobility and bioavailability of potentially toxic elements (PTEs) in an industrial soil phytostabilized by Dactylis glomerata L. or a mixed stand of grasses (Lolium perenne L., Poa pratensis L. and Festuca arundinacea Shreb.). The soil showed very high pseudototal and bioavailable concentrations of cadmium (Cd) and lead (Pb), due to improper lead-acid batteries storage. Compost amendment in combination with the two biostimulants produced the best outcomes in terms of plant growth and nutrient uptake. The same mix of beneficial microbes improved soil biological fertility enhancing soil nitrogen fixing and ammonia oxidizing bacteria, while reduced the pore water and NH4NO3 extractable concentrations of Cd and at lower extent of Pb in soil. Accordingly, the lower mobility and bioavailability of Cd in soil determined a lower uptake and accumulation of Cd in shoots of different grass species. Our results suggest that a green cap with turfgrass assisted by biostimulants and compost amendment in PTE-contaminated industrial sites could be a reliable and effective practice to protect and restore soil biological fertility and to reduce the risk of PTE dispersion in the surrounding environment.

In agricultural soils, thallium (Tl) of geogenic origin may represent a potential risk for human health, mainly via ingestion of food crops. In this work, a pot experiment was carried out to evaluate (1) the bioavailability of Tl and other potentially toxic elements (PTEs) in an agricultural soil with naturally occurring Tl, (2) the uptake and accumulation of PTEs in Lactuca sativa L. var. acephala, Diplotaxis tenuifolia L. DC and Silene latifolia Poir, (3) the health risks arising from plant and soil ingestion by different subpopulations and dermal contact of soil by farmers. In soil, only Tl and Pb pseudototal contents were above Italian screening values. Nevertheless, the promptly bioavailable contents of all PTEs were always below internationally recognized trigger values. Plants affected PTE bioavailability in soil by their rhizodepositions and accumulated PTEs in their shoots. Acceptable risks (hazard index &lt, 1) arose from dietary intake of both L. sativa L., D. tenuifolia L. and dermal contact of soil by farmers. Significant health risks can derive from the intake of S. latifolia Poir. (accumulating high Tl concentrations), in particular by children (HI = 74). In conclusion, an adequate management and crop selection are needed to profitably exploit soils with geogenic Tl for agricultural purposes.

Heavy payloads in future shuttle journeys to Mars present limiting factors, making self-sustenance essential for future colonies. Therefore, in situ resources utilization (ISRU) is the path to successful and feasible space voyages. This research frames the concept of planting leafy vegetables on Mars regolith simulant, ameliorating this substrate&rsquo, s fertility by the addition of organic residues produced in situ. For this purpose, two butterhead lettuce (Lactuca sativa L. var. capitata) cultivars (green and red Salanova&reg, ) were chosen to be cultivated in four different mixtures of MMS-1 Mojave Mars simulant:compost (0:100, 30:70, 70:30 and 100:0, v:v) in a phytotron open gas exchange growth chamber. The impact of compost rate on both crop performance and the nutritive value of green- and red-pigmented cultivars was assessed. The 30:70 mixture proved to be optimal in terms of crop performance, photosynthetic activity, intrinsic water use efficiency and quality traits of lettuce. In particular, red Salanova&reg, showed the best performance in terms of these quality traits, registering 32% more phenolic content in comparison to 100% simulant. Nonetheless, the 70:30 mixture represents a more realistic scenario when taking into consideration the sustainable use of compost as a limited resource in space farming, while still accepting a slight significant decline in yield and quality in comparison to the 30:70 mixture.

The configuration of a biologically active and fertile substrate consisting mainly of Martian regolith to facilitate the growth of edible plants during long-term manned missions to Mars constitutes one of the main challenges in spatial research. Regolith amendment with compost derived from recycled crew effluent crop waste generated by bioregenerative life support systems constitutes a substrate that may contribute to upgrade crew autonomy and long-term survival in space. In this context, the present work aimed to: i) study the geochemical and mineralogical composition of MMS-1 Mars simulant and the physicochemical and hydraulic properties of mixtures obtained by mixing MMS-1 and green compost at varying rates (0:100, 30:70, 70:30, 100:0; v:v); ii) evaluate the potential use of MMS-1 as growing medium of two lettuce cultivars; iii) assess how compost addition may impact on sustainability of space agriculture exploiting local resources. MMS-1 is a coarse-textured alkaline substrate consisting mostly of plagioclase, amorphous material and, to a lesser extent, zeolite, hematite and smectites. Although it can be source of nutrients, it lacks of organic matter, nitrogen (N), phosphorus (P) and sulphur (S), which may be supplied by compost. Both lettuce (Lactuca sativa L.) cultivars were able to grow on all mixtures for 19 days under fertigation. Red Salanova lettuce produced a statistically-greater dry biomass, leaf area and number than green Salanova. Leaf area and plant dry biomass were higher on 30:70 simulant/compost mixture. The shoot/root ratio of plants decreased as simulant in growth substrate increased. Lack of biological fertility and possible salt stress negatively impacted on plants grown in non-amended simulant. Our results show that it is possible to grow crops in Martian simulants adequately amended and fertilized. However, many remaining issue warrant further investigation concerning the dynamics of compost production, standardization of supply during long-term manned missions and representativeness of simulants to real Martian regolith.

The configuration of a biologically fertile substrate for edible plant growth during long-term manned missions to Mars constitutes one of the main challenges in space research. Mars regolith amendment with compost derived from crew and crop waste in bioregenerative life support systems (BLSS) may generate a substrate able to extend crew autonomy and long-term survival in space. In this context, the aim of our work was threefold: first, to study the geochemistry and mineralogy of Mojave Mars Simulant (MMS-1) and the physico-chemical and hydraulic properties of mixtures obtained by mixing MMS-1 and green compost at varying rates (0:100, 30:70, 70:30, 100:0; v:v); secondly, to evaluate the potential use of MMS-1 as a growing medium of two lettuce (Lactuca sativa L.) cultivars; thirdly, to assess how compost addition may impact on sustainability of space agriculture by exploiting in situ resources. MMS-1 is a coarse-textured alkaline substrate consisting mostly of plagioclase, amorphous material and secondarily of zeolite, hematite and smectites. Although it can be a source of nutrients, it lacks organic matter, nitrogen, phosphorus and sulphur, which may be supplied by compost. Both cultivars grew well on all mixtures for 19 days under fertigation. Red Salanova lettuce produced a statistically higher dry biomass, leaf number and area than Green Salanova. Leaf area and plant dry biomass were the highest on 30:70 simulant:compost mixture. Nevertheless, the 70:30 mixture was the best substrate in terms of pore-size distribution for water-plant relationship and the best compromise for plant growth and sustainable use of compost, a limited resource in BLSS. Many remaining issues warrant further investigation concerning the dynamics of compost production, standardisation of supply during space missions and representativeness of simulants to real Mars regolith.

Metal uptake capacity and growth patterns of three cardoon cultivars (Sardo, Siciliano, and Spagnolo) were investigated for phytoremediation in a metal-contaminated soil. Metal concentrations after one and two growth rounds were measured in soil and plants by ICP-MS. Potentially and promptly available metal fractions were estimated by EDTA and ammonium nitrate. Plant weight, water and nitrogen content, and life span were considered as growth parameters. After the first growth cycle, a significant accumulation of all elements was observed in roots, whereas only Cd, Cu, Fe, Pb, and Sb were significantly translocated to the shoots. After the second growth cycle, a further significant increase, especially in roots, was observed in all cultivars and for all elements considered. High percentages of the potentially available fraction were found for As, Cd, Cu, Pb, and Sb. Metal concentrations in plants were far higher than the promptly available fraction, indicating an increase of metal bioavailability during culture rounds. A severe decrease of weight and life span was observed in Sardo and Siciliano grown on polluted soil, along with an increase in N content. The cultivar Spagnolo, harmonizing a high ability of metal uptake and tolerance, proved the most efficient cultivar in metal phytoremediation.

Carrot (Daucus carota L.) is a widely consumed root vegetable, whose growth and safety might be threatened by growing-medium arsenic (As) contamination. By this work, we evaluated the effects of humic acids from Leonardite and NPK mineral fertilisation on As mobility and availability to carrot plants grown for 60 days in a volcanic soil irrigated with As-contaminated water - representing the most common scenario occurring in As-affected Italian areas. As expected, the irrigation with As-contaminated water caused a serious toxic effect on plant growth and photosynthetic rate; the highest rate of As also inhibited soil enzymatic activity. In contrast, the organic and mineral fertilisation alleviated, at least partially, the toxicity of As, essentially by stimulating plant growth and promoting nutrient uptake. The mobility of As in the volcanic soil and thus its phytoavailability were differently affected by the organic and mineral fertilisers; the application of humic acids mitigated the availability of the contaminant, likely by its partial immobilisation on humic acid sorption sites - thus raising up the intrinsic anionic sorption capacity of the volcanic soil; the mineral fertilisation enhanced the mobility of As in soil, probably due to competition of P for the anionic sorption sites of the soil variable-charge minerals, very affine to available P. These findings hence suggest that a proper soil management of As-polluted volcanic soils and amendment by stable organic matter might mitigate the environmental risk of these soils, thus minimising the availability of As to biota.

The risks for human health and the ecosystem due to potentially toxic elements (PTEs) were investigated in a farmland classified as potentially contaminated by Cr and Zn by analysing native vegetation and relative rhizo-soils. Rhizo-soils of different plant species were found to be enriched by Cr and Zn as well as by elements omitted from official environmental characterization, namely Cd, As and Pb. The ecological risk index (ERI) had a mean value of 510, indicating high to “very high” risk in different habitats. ERI above the very high risk threshold characterized the rhizo-soils of Lolium perenne , Erigeron sumatrensis , Oloptum thomasii and Amaranthus retroflexus . Two of these plant species ( E. sumatrensis and A. retroflexus ) are exotic in Italy and accumulated Cd in the shoots above the EU threshold for forage, suggesting a potential risk of Cd transfer to the food chain. Hence, this element was found to contribute most to the ERI. Cynodon dactylon was recognized as the most suitable plant species for the phytostabilization of the contaminated site, as it showed the highest bioavailable Cd accumulation in roots coupled with the highest frequency and soil-cover capacity during spring-summer, when the risk of soil resuspension is generally more intense.

The influence of Trichoderma fungi on growth, yield and nutrient status of food crops has been widely studied. However, a lack of knowledge still exists on the effect of agricultural soils with different geological nature, land use and management on Trichoderma-plant interaction. This study aims to evaluate the influence of three soil types, with different physicochemical properties and under fertilization by NPK-based nutrient solutions, on the efficacy of two T. harzianum (T22 and M10) strains on the growth, nutrient uptake and glucosinolate concentration in Brassica rapa subsp. sylvestris cv. esculenta. Overall data showed that the biofertilization by Trichoderma strains is very effective to enhance the fertility and productivity of the nutrient-poor soils even in the absence of fertilization by NPK-nutrient solutions, as well as to stimulate the production of glucosinolates by foliar biomass of B. rapa, although this effect was strongly dependent on the soil type.

The mobility, bioavailability, and toxicity of metal(- loid)s are influenced by their interactions with phyllosilicates, organic matter, variable charge minerals, and microorganisms. Physicochemical processes influencing the chemistry of metal(- loid)s in soil environments include sorption/desorption, solution complexation, oxidation-reduction, and precipitationdissolution reactions. In particular, the sorption/desorption reactions of metal(loid)s on/from soil sorbents are influenced by pH, nature of soil components, and presence and concentrations of cations and inorganic anions. In recent years, many extraction tests have been used for assessing trace elements mobility and phytoavailability. Chemical speciation of toxic elements may be achieved by spectroscopic analyses (XAS), which provide information about oxidation state, symmetry, and identity of the coordinating ligand environment, and possible solid phases.

Large variability in the spatial distribution and content of metals is generally recognised in anthropogenically-polluted soils, hence, a detailed site investigation implying the collection and analysis of a large number of soil samples is often necessary. To this regard, the selection of a rapid, cost-effective and accurate analytical technique to assess the concentration of metals in soil is of paramount importance. The overall objective of this work was to evaluate the possibility of assessing the aqua regia-extractable (AR) content of metals in soil from the multi-element profile of the soil obtained by a portable X-ray fluorescence analyser (pXRF). To this objective, we attempted: (i) to establish, by simple linear regressions, the relations occurring between the metal contents measured by pXRF and AR in laboratory setting on air-dried and 2 mm-sieved soil samples from two case studies (A-agricultural and B-industrial sites); (ii) to define metal-based linear models predicting metal AR contents from pXRF measurements; (iii) to assess the influence of metal properties and sources on relations found between the two analytical methods. Very satisfying correlations (R2 > 0.90) were observed between the AR and pXRF contents of Ca, Cu, Cr, Ni, Pb and Zn in the site A, and of Cd, Cu, Pb and Zn in the site B. For the majority of metals, lower AR than pXRF contents were measured, as result of the AR incomplete dissolution of metal-bearing silicates. This was not observed when metals - of anthropogenic origin - occurred in soil in very high concentrations (i.e., Cr for A and Pb for B). In both sites, the comparison among different regression parameters revealed a strong metal-dependence. Moreover, for most of the metals, the parameters of each metal-regression line significantly differed between the two case studies, indicating site-dependence of regression fits.

This review provides insights on (1) the chemistry of arsenic (As) in the soil environment and factors (e.g., pH, presence, nature, and concentration of competing inorganic and organic ligands), which regulate the sorption/desorption of arsenate and arsenite (the most abundant As species in soils and waters) on/from soil components; (2) the chemical fractionation and speciation of As to identify species that are more mobile and phytoavailable; and finally (3) the uptake of As by selected edible plants and production techniques able to reduce its translocation in plant tissues.

In soil environments the formation of simple coprecipitates formed by the interaction of two or more cations and/or anions are the rule and not the exception. In this review we describe the formation, the nature and the reactivity of coprecipitates formed by the interaction between cations (Fe, Al, Mg, Mn, Zn) with the formation of mixed oxides or layered double hydroxides (LDHs) and of coprecipitates formed by the interactions of inorganic and low molecular mass organic (LMMOLs) ligands with OH-Al and/or OH-Fe species both in the absence or presence of phyllosilicates. The presence of anions within these samples strongly affect the sorption of other ligands on the surfaces of the coprecipitates. Furthermore, the anions coprecipitated with Al and/or Fe hydrolytic products are only partially replaced even by ligands with strong affinity for the surfaces of the final samples, clearly because they are also incorporated into the network of the precipitates. We also describe the formation, surface properties and reactivity of binary complexes obtained by the interaction of hydrolytic products of Al and Fe with clay minerals and of ternary OH-Al(-Fe)-organics-phyllosilicates (organics included also large anions as tannate or proteins). The effect of the sequence of addition of the components of the final organomineral complexes influenced the physicochemical and mineralogical properties of the samples. Attention was also devoted to the stabilization of organic substances in organo-mineral coprecipitates and soils.

The competitive sorption of Cu, Cr and Pb on a ferrihydrite and two synthetic organomineral complexes, obtained by coprecipitating iron with different quantities of oxalate and tartrate were studied. Greater amounts (μmol/m2) of heavy metals were sorbed onto the organomineral complexes than ferrihydrite, the higher the carbon content in the samples the greater the sorption of heavy metals. Lead was sorbed much more and more tightly than Cr and Cu on the sorbents. In binary systems, the sorption and the inhibitive efficiency of one metal (M1) to the other (M2) were affected by the nature of the metal, initial M2/M1 molar ratio, addition sequence of M1 and M2, and residence time. Lead showed a much greater capacity to inhibit the sorption of the other two metals, whereas the opposite was true for Cu. In ternary systems, when equimolar amounts of each metal were added, the sorbents were covered with more than 50% by Pb alone. However, even in the presence of large excess of Pb and Cr, considerable extent of Cu sorption still occurred regardless of sorbent types, indicating that some sorption sites on each sorbent had a high affinity for Cu. The results of this study would contribute to further our current understanding on the mobility of multi heavy metals in soils and related environments.

Arsenic (As) co-precipitation is one of the major processes controlling As solubility in soils and waters. When As is co-precipitated with Al and Mg, the possible formation of layered double hydroxides (LDHs) and other nanocomposites can stabilize As in their structures thus making this toxic element less available. We investigated the nature and reactivity of Mg-Al-arsenate [As(V)] co-precipitated LDHs formed in solution affected by As concentration, pH, and aging. At the beginning of the co-precipitation process, poorly crystalline LDH and non-crystalline Al(Mg)-oxides form. Prolonged aging of the samples promotes crystallization of LDHs, evidenced by an increase in As K XANES intensities and XRD peak intensities. During aging Al- and/or Mg-oxides are likely transformed by dissolution/re-precipitation processes into more crystalline but still defective LDHs. Surface area, chemical composition, reactivity of the precipitates, and anion exchange properties of As(V) in the co-precipitates are influenced by pH, aging, and As concentration. This study demonstrates that (i) As(V) retards or inhibits the formation and transformation of LDHs and (ii) more As(V) is removed from solution if co-precipitated with Mg and Al than by sorption onto well crystallized LDHs.

Phytoremediation technology is emerging as a promising environment-friendly method for large-scale cleanup of arsenic (As) contaminated water and soil. In this study we investigated the effect of arbuscular mycorrhizal fungi (AMF - Glomus spp.) on the growth of the vetiver grass (Chrysopogon zizanioides L.) and its As uptake from contaminated hydroponic and soil systems. An ameliorative effect of the AMF inoculation in enhancing plants growth was found, mainly by stimulating the development of their root system. In addition, AMF-inoculated plants also took up more As from both contaminated systems compared to non-inoculated plants, although the differences were not always statistically significant (p < 0.05). Nevertheless, more efficient As uptake by vetiver grass from contaminated hydroponic solutions than spiked soils was observed, essentially because of the higher phytoavailability in the former contaminated system. Furthermore, plants grown hydroponically also translocated higher amounts of As from their roots to shoots. Therefore, the findings of this study reveals that the use of vetiver grass technology in conjunction with AMF would be more appropriate to decontaminate As-contaminated water than soils.

We have studied the effects of P fertilization and AMF inoculation on the growth of escarole (Chicorium endivia L.) plants, grown in both As-non-contaminated (Padula) and As-contaminated (La Botte) soils and As and P uptake by these plants. Our study demonstrated that the combined use of AMF inoculation and P fertilization can significantly increase the production of biomass of escarole plants, even if grown in highly As-contaminated soils. In addition, this dual agricultural practice has also allowed to reduce the translocation of the harmful element from roots to leaves minimizing, hence, the accumulation of highly toxic levels of As in the edible part of the escarole. Therefore, the combined use of AMF inoculation and P fertilization may alleviate the As toxicity to sensitive plants as Cichorium endivia, by promoting their growth, limiting As assimilation and improving P nutrition.

Biomass-derived biochar is considered as a promising heavy metal adsorbent, due to abundance of polar functional groups, such as carboxylic, hydroxyl, and amino groups, which are available for heavy metal removal. The aims of this study were to evaluate the effectiveness of an orchard pruning-derived biochar in removing some heavy metals (through the evaluation of isotherms) and to study water dynamics at the solid-liquid interface as affected by heavy metal adsorption (through an innovative nuclear magnetic resonance (NMR) relaxometry approach). Both isotherms and NMR spectra revealed that Pb and Cr showed a good affinity for the biochar surface (Pb > Cr), while Cu was less affine. Accordingly, higher amounts of Pb and Cr were adsorbed by biochar as compared to those of Cu in the single systems. In binary systems (i.e., when two metals were applied simultaneously), Pb showed the highest inhibition of the adsorption of the other two metals, whereas the opposite was evidenced when Cu was used; the competitive adsorption was also strongly influenced by the metal residence time on biochar surface. In ternary systems (i.e., when all metals were applied simultaneously), even in the presence of high amounts of Pb and Cr, considerable adsorption of Cu occurred, indicating that some biochar adsorption sites were highly specific for a single metal.

Arsenic pollution is currently a major health issue because As is toxic for human beings, animals, and plants. Knowledge of As mobility is therefore important to assess health risk. The sorption of arsenite and arsenate on metal oxides in the presence of various anionic ligands is closely linked to the mobility, bioavailability, and risk. It was reported that the sorption mechanisms and characteristics of arsenite and arsenate on Al-oxides were different from that on Fe-oxides. Previous work reports the sorption of arsenite and arsenate on Fe-oxides in the presence of ligands. Whereas there is few knowledge on the sorption of arsenite and arsenate by Al-oxides in the presence of ligands. Here, we studied the sorption of arsenite and arsenate on amorphous Al-oxide by batch experiments. We tested the effect of organic ligands: oxalate, malate, tartrate, citrate; and inorganic ligands: sulfate, phosphate, selenate, selenite. Results show that amorphous Al-oxide has more sorption affinity for arsenate than arsenite. The inhibition of As sorption by ligands at pH 6 is higher for arsenite than arsenate. For arsenite, the As sorption inhibition decreases in the order phosphate, citrate, malate, selenite, oxalate, tartrate, sulfate, and selenate. For arsenate, the As sorption inhibition decreases in the order phosphate, malate, citrate, selenite, tartrate, oxalate, sulfate, and selenate.

Layered double hydroxides (LDHs) show excellent capacity to sorb and exchange anions. Although arsenic (As) has a high affinity for sorbents containing Fe, only few studies have been carried out on the sorption of arsenite [As(III)] onto a Fe-based LDH. In this work we studied the sorption of As(III) onto a LDH containing Mg and Fe (Mg–Fe-LDH), as affected by: (i) pH; (ii) the presence of increasing concentrations of organic [citrate (CIT) and oxalate (OX)] and inorganic [phosphate (PO 4 ), selenite (SeO 3 ) and sulphate (SO 4 )] ligands, (iii) the effect of residence time on the desorption of As(III) by these ligands, and; (iv) the kinetics of desorption of As(III) by PO 4 . The As(III) sorption isotherms, carried out at different pHs, indicated a good affinity of the harmful oxyanion for the sorption sites of the Mg–Fe-LDH. This material was able to remove efficiently As(III) from contaminated solutions over a wide range of pH, but more in acidic than in alkaline systems. Competing ligands differently prevented the As(III) sorption on Mg–Fe-LDH, according to the following order: SO 4 3 4 . The desorption of As(III) by these anions decreased with increasing As(III) residence time on LDH surfaces. A comparison between the sorption/desorption of As(III) and As(V) on/from Mg–Fe-LDH in the presence or absence of anions highlights that less As(III) than As(V) is sorbed, whereas more As(III) than As(V) is desorbed by all the selected organic and inorganic ligands, but PO 4 .

Arsenite [As(III)] and arsenate [As(V)] sorption by Fe- and Al-based drinking-water treatment residuals (WTR) was studied as a function of particle size at different pHs, and in the presence of competing ligands, namely, phosphate, citrate, and oxalate. Both WTRs showed high affinity for As oxyanions. However, Al-WTR showed higher As(III) and As(V) sorption capacity than Fe-WTR because of their greater surface area. The effect of particle size on As sorption was pronounced on Fe-WTR, where the smaller fraction sorbed more As(III) and As(V) than the larger fractions, whereas relatively minor effects of particle size on As sorption was observed for Al-WTR. Arsenite sorption on both WTRs increased with increasing pH up to circum-neutral pHs and then decreased at higher pHs, whereas As(V) sorption decreased steadily with increasing pH. The capacity of competing ligands to inhibit sorption was greater for As(III) than As(V) on both WTRs (particularly on Al-WTR) following the sequence: oxalate.

We have studied the uptake and distribution of arsenic (As) and phosphorus (P) in roots, shoots and berries of tomato plants, grown on uncontaminated soil, irrigated with As-contaminated solutions at four concentrations (0, 0.5, 2 and 4 mg L -1 ), in presence or absence of P fertilization.The biomass of tomato plants decreased with increasing As concentration in irriga-tion water, especially tomato berries. In addition, the reduction of biomasses was significantly greater in plants non-fertilized with P. The beneficial effect generated with the P addition indicated that this nutrient played an important role in alleviating As toxicity in tomato plants. The higher the As concentration in irrigation water the higher the As concentration in plant tissues; most of the As absorbed by plants was accumulated in their roots. Phosphorus application has allowed to reduce As trans-location toward tomato berries, enhancing plant P status. These observations may be useful for certain areas of the World, in which As-contaminated waters are used for agricultural purposes.Keywords: tomato, arsenic, uptake, phosphorus fertilization, contamination.

The influence of compost on the growth of bean plants irrigated with As-contaminated waters and its influence on the mobility of As in the soils and the uptake of As (as NaAs III O 2 ) by plant components was studied at various compost application rates (3·10 4 and 6·10 4 kg ha −1 ) and at three As concentrations (1, 2 and 3 mg kg −1 ). The biomass and As and P concentrations of the roots, shoots and beans were determined at harvest time, as well as the chlorophyll content of the leaves and nonspecific and specifically bound As in the soil. The bean plants exposed to As showed typical phytotoxicity symptoms; no plants however died over the study. The biomass of the bean plants increased with the increasing amounts of compost added to the soil, attributed to the phytonutritive capacity of compost. Biomass decreased with increasing As concentrations, however, the reduction in the biomass was significantly lower with the addition of compost, indicating that the As phytotoxicity was alleviated by the compost. For the same As concentration, the As content of the roots, shoots and beans decreased with increasing compost added compared to the Control. This is due to partial immobilization of the As by the organic functional groups on the compost, either directly or through cation bridging. Most of the As adsorbed by the bean plants accumulated in the roots, while a scant allocation of As occurred in the beans. Hence, the addition of compost to soils could be used as an effective means to limit As accumulation in crops from As-contaminated waters.

This paper describes the sorption of arsenate on Al-Mg and Fe-Mg layered double hydroxides as affected by pH and varying concentrations of inorganic and organic ligands, and the effect of residence time on the desorption of arsenate by ligands. The capacity of ligands to inhibit the fixation of arsenate followed the sequence: nitrate < nitrite < sulphate < selenite < tartrate < oxalate < phosphate on Al-Mg-LDH and nitrate < sulphate ≈ nitrite < tartrate < oxalate < selenite ≪ phosphate on Fe-Mg-LDH. The inhibition of arsenate sorption increased by increasing the initial ligand concentration and was greater on Al-Mg-LDH than on Fe-Mg-LDH. The longer the arsenate residence time on the LDH surfaces the less effective the competing ligands were in desorbing arsenate from sorbents. A greater percentage of arsenate was removed by phosphate from Al-Mg-LDH than from Fe-Mg-LDH, due to the higher affinity of arsenate for iron than aluminum.

We studied the sorption of As(III) and As(V) onto ferrihydrite as affected by pH, nature and concentration of organic [oxalic (OX), malic (MAL), tartaric (TAR), and citric (CIT) acid] and inorganic [phosphate (PO(4)), sulphate (SO(4)), selenate (SeO(4)) and selenite (SeO(3))] ligands, and the sequence of anion addition. The sorption capacity of As(III) was greater than that of As(V) in the range of pH 4.0-11.0. The capability of organic and inorganic ligands in preventing As sorption follows the sequence: SeO(4) ≈ SO(4) < OX < MAL ≈ TAR < CIT < SeO(3) ≪ PO(4). The efficiency of most of the competing ligands in preventing As(III) and As(V) sorption increased by decreasing pH, but PO(4) whose efficiency increased by increasing pH. In acidic systems all the competing ligands inhibited the sorption of As(III) more than As(V), but in alkaline environments As(III) and As(V) seem to be retained with the same strength on the Fe-oxide. Finally, the competing anions prevented As(III) and As(V) sorption more when added before than together or after As(III) or As(V).

The competitive sorption among Cu, Pb and Cr in ternary system on Na-montmorillonite at pH 3.5, 4.5 and 5.5 and at different heavy metal concentrations, and the effect of varying concentrations of Al, Fe, Ca and Mg on the sorption of heavy metals were studied. Competitive sorption of Cu, Pb and Cr in ternary system on montmorillonite followed the sequence of Cr ≫ Cu > Pb. Moreover, the competition was weakened by the increase of pH while was intensified by the increase of heavy metal concentration. The sorption of heavy metal on montmorillonite was inhibited by the presence of Ca and Mg, while Al and Fe showed different patterns in affecting heavy metal sorption. Aluminum and Fe generally inhibited the sorption of heavy metal when the pH and/or concentration of major elements were relatively low. However, promoting effects on heavy metal sorption by Al and Fe were found at relatively high pH and/or great concentration of major elements. The inhibition of major elements on heavy metal sorption generally followed the order of Al > Fe > Ca ≥ Mg, while Fe was more efficient than Al in promoting the sorption of heavy metals. These findings are of fundamental significance for evaluating the mobility of heavy metals in polluted environments.

In soil environments, sorption/desorption reactions as well as chemical complexation with inorganic and organic ligands and redox reactions, both biotic and abiotic, are of great importance in controlling their bioavailability, leaching and toxicity. These reactions are affected by many factors such as pH, nature of the sorbents, presence and concentration of organic and inorganic ligands, including humic and fulvic acid, root exudates, microbial metabolites and nutrients. In this review, we highlight the impact of physical, chemical, and biological interfacial interactions on bioavailability and mobility of metals and metalloids in soil. Special attention is devoted to: i) the sorption/desorption processes of metals and metalloids on/from soil components and soils; ii) their precipitation and reduction-oxidation reactions in solution and onto surfaces of soil components; iii) their chemical speciation, fractionation and bioavailability.

The role of phosphorus (P) application and arbuscular mycorrhizal fungi (AMF) on growth, arsenic (As) and P accumulation in lettuce plants growing in an As-polluted soil (total As 250 mg kg−1), was investigated. In particular, it was tested whether application of a commercial inoculum (CI), with (+P at 90 kg P ha−1) and without (−P at 0 kg P ha−1) P fertilizer, supported greater plant growth and provided more P, enhancing As tolerance, than indigenous fungi alone. The influence of these treatments on As and P availability in the rhizosphere and bulk soils was also investigated. Greenhouse pot experiments were established where plants were grown with and without commercial inoculum (+CI, −CI) in unsterilized conditions. Inoculation with commercial inoculum and P application together considerably increased plant biomass, by enhancing host plant P nutrition and lowering shoot and root As concentrations compared to plants inoculated only with native AMF. In the rhizosphere of +CI+P plants there was P soil depletion compared to −CI+P. The results evidenced that, with P addition, inoculation with commercial inoculum alleviated the toxicity of excessive As by improving P nutrition without increasing As concentrations in the plant, emphasizing the role of beneficial microbes and P fertilizer to improve soil fertility in As-contaminated soil.