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The study of soils to assess their condition and potential use is an internationally established practice. The greatest interest corresponds to agricultural soils and their heavy metal content, given their impact on food production. The presence of heavy metals in the soil can alter the sustainability of the food chain, causing potential risks to human and animal health. The objective of this study was to systematize the information available in the last ten years on studies of heavy metal contamination in the agricultural soils of the countries of the Insular Caribbean. A search was conducted in the Scopus, Web of Science and Google Scholar databases for the period 2012-2021. The different sources of heavy metal contamination of agricultural soils, its effects on the soil, on plants and on human and animal health, the contamination rates and the experiences of studies of heavy metal contamination in agricultural soils of the countries of the Insular Caribbean were examined, resulting in very few and little information on the reference values of heavy metals in agricultural soils. [ABSTRACT FROM AUTHOR]

The effects of high Cu, Pb, and Zn concentrations on pigments of Pinus massoniana L. (PML) growing near the Dabaoshan Pb-Zn polymetallic mine were evaluated. A total of 19 samples of PML needles and 15 samples of soil were collected near the mine and at a nearby background site to compare heavy metal (HM,Zn, Cu, Pb) accumulations. A 2D scatter plot was used to study the relationships between the pigments and each metal element. PML needles collected from the mining area had a significantly higher content of Pb (24.5 mg/kg) and Cu (26.1 mg/kg) than needles collected from the background site (Pb: 2.8 mg/kg, Cu: 6.7 mg/kg). The HM concentrations in the needles were positively correlated with the pigment contents (chlorophyll a, chlorophyll b and carotenoids) . This suggests that PML can adapt toHMstress and even promote growth within a certain range. In contrast, when the HM content in needles reached very high values (Cu: 50 mg/kg, Pb: 60 mg/kg, and Zn: 110 mg/kg), the normal physiological and biochemical functions were hindered. PML is highly resistant to HM pollution, making it a candidate for reforestation and restoration of Pb and other HMs in mine areas. [ABSTRACT FROM AUTHOR]

Human activities generate environmental stresses that can lead plant populations to become extinct. Population survival would require the evolution of adaptive responses that increase tolerance to these stresses. Thus, in pseudometallophyte species that have colonized anthropogenic metalliferous habitats, the evolution of increased metal tolerance is expected in metallicolous populations. However, the mechanisms by which metal tolerance evolves remain unclear. In this study, parent populations were created from non-metallicolous families of Noccaea caerulescens. They were cultivated for one generation in mesocosms and under various levels of zinc (Zn) contamination to assess whether Zn in soil represents a selective pressure. Individual plant fitness estimates were used to create descendant populations, which were cultivated in controlled conditions with moderate Zn contamination to test for adaptive evolution in functional traits. The number of families showing high fitness estimates in mesocosms was progressively reduced with increasing Zn levels in soil, suggesting increasing selection for metal tolerance. In the next generation, adaptive evolution was suggested for some physiological and ecological traits in descendants of the most exposed populations, together with a significant decrease of Zn hyperaccumulation. Our results confirm experimentally that Zn alone can be a significant evolutionary pressure promoting adaptive divergence among populations. [ABSTRACT FROM AUTHOR]

Heavy metal concentrations in agricultural fields and their ecological risks are a source of extensive concern worldwide. A field survey was conducted to investigate the present situation and health risks of heavy metals (Mn, Pb, Zn, Cu, and Cd) and crops (corn, green soybean, sweet potato, persimmon, cassava, and Chinese chestnut) around the Pingle manganese (Mn) mine site in Guangxi Province, China, which was abandoned 20 years ago. The results showed that the ranges of Mn, Pb, Zn, Cu, and Cd were 2706.54-6760.16, 229.37-275.84, 160.39-215.48, 58.11-75.30, and 5.78-6.98 mg kg−1, respectively, which were approximately 15.38-38.41, 11.76-14.15, 2.12-2.85, 2.09-2.71, and 21.64-28.75 times greater than their respective background values. Most of these concentrations exceeded the national standard for soil quality (grade 2) developed by the Ministry of Environmental Protection of China (1995). Contamination assessments based on the single contamination index (Pi), Nemerow multi-factor index (Pcom), and potential ecological risk index (RI) showed that the sampled soils were severely polluted with these heavy metals, especially Pb and Cd. Similarly, the crops were enriched with Pb and Cd, with concentrations of 10.22-41.78 and 2.33-5.37 mg kg−1, respectively, which were much higher than the threshold values of the national food standards. Contamination assessments with Pi and Pcom also showed that the crops were severely polluted with Pb and Cd. The bioaccumulation factor values for Cd were highest among the heavy metals, with an average mean of 0.66 in these six crops, demonstrating that Cd readily accumulates in these crops. An assessment showed that the health risk for adults living in the mining-impacted areas was significant. Our study strongly recommends that heavy metal contamination in agricultural soils and crops grown around the Pingle Mn mining-affected areas should be treated to mitigate the health risks. [ABSTRACT FROM AUTHOR]

Radiocesium in water, soil, and air represents a severe threat to human health and the environment. It either acts directly on living organisms from external sources, or it becomes incorporated through the food chain, or both. Plants are at the base of the food chain; it is therefore essential to understand the mechanisms of plants for cesium retention and uptake. In this review we summarize investigations about sources of stable and radioactive cesium in the environment and harmful effects caused by internal and external exposure of plants to radiocesium. Uptake of cesium into cells occurs through molecular mechanisms such as potassium and calcium transporters in the plasma membrane. In soil, bioavailability of cesium depends on the chemical composition of the soil and physical factors such as pH, temperature and tilling as well as on environmental factors such as soil microorganisms. Uptake of cesium occurs also from air through interception and absorption on leaves and from water through the whole submerged surface. We reviewed information about reducing cesium in the vegetation by loss processes, and we extracted transfer factors from the available literature and give an overview over the uptake capacities of 72 plants for cesium from the substratum to the biomass. Plants with high uptake potential could be used to remediate soil and water from radiocesium by accumulation and rhizofiltration. Inside plants, cesium distributes fast between the different plant organs and cells, but cesium in soil is extremely stable and remains for decades in the rhizosphere. Monitoring of contaminated soil therefore has to continue for many decades, and edible plants grown on such soil must continuously be monitored. [ABSTRACT FROM AUTHOR]

Environmental contamination by hazardous heavy metals/metalloids (metal(loid)s) is growing worldwide. To restrict the migration of toxic contaminants, the establishment of a self-sustainable plant cover is required. Plant growth in multi-polluted soils is a challenging issue not only by metal(loid) toxicities, but also by the co-occurrence of other stressors. Dittrichia viscosa is a pioneer Mediterranean species able to thrive in metal(loid)-enriched tailings in semi-arid areas. The aim of the present work was to examine the metabolic adjustments involved in the acclimation responses of this plant to conditions prevailing in mine-tailings during Mediterranean spring and summer. For this purpose, fully-expanded leaves, and rhizosphere soil of both mining and non-mining populations of D. viscosa grown spontaneously in south-eastern Spain were sampled in two consecutive years. Quantitative analysis of > 50 biochemical, physiological and edaphic parameters were performed, including nutrient status, metal(loid) contents, leaf redox components, primary and secondary metabolites, salicylic acid levels, and soil physicochemical properties. Results showed that mining plants exhibited high foliar Zn/Pb co-accumulation capacity, without substantially affecting their photosynthetic metabolism or nutritional status even in the driest summer period. The comparison of the antioxidative/oxidative profile between mining and non-mining D. viscosa populations revealed no major seasonal changes in the content of primary antioxidants (ascorbate and GSH), or in the levels of ROS. Multivariate analysis showed that phenylalanine ammonia-lyase (PAL) and peroxidase (PRX) activities and soluble and cell wall-bound phenols were potential biomarkers for discriminating between both populations. During the dry season, a marked enhancement in the activity of both PAL and soluble PRX resulted in both a drop in the accumulation of soluble phenols and an increase of the strong metal chelator caffeic acid in the cell-wall fraction, supporting the view that the plasticity of phenylpropanoid metabolism provide an effective way to counteract the effects of stress combinations. [ABSTRACT FROM AUTHOR]

Cadmium contamination in soil is a substantial global problem, and of significant concern due to high food-chain transfer. Cadmium hyperaccumulators are of particular interest because of their ability to tolerate and take up significant amounts of heavy metal pollution from soils. One particular plant, Noccaea caerulescens (formerly, Thlaspi caerulescens ), has been extensively studied in terms of its capacity to accumulate heavy metals (specifically Zn and Cd), though these studies have primarily utilized hydroponic and metal-spiked model soil systems. We studied Cd and nutrient uptake by two N . caerulescens ecotypes, Prayon (Zn-only hyperaccumulator) and Ganges (Zn- and Cd-hyperaccumulator) in four long-term field-contaminated soils. Our data suggest that individual soil properties such as total soil Cd, Zn:Cd molar ratio, or soil pH do not accurately predict Cd uptake by hyperaccumulating plants. Additionally, total Cd uptake by the hyperaccumulating Ganges ecotype was substantially less than its physiological capacity, which is likely due to Cd-containing solid phases (primarily iron oxides) and pH that play an important role in regulating and limiting Cd solubility. Increased P accumulation in the Ganges leaves, and greater plant Fe accumulation from Cd-containing soils suggests that rhizosphere alterations via proton, and potentially organic acid, secretion may also play a role in nutrient and Cd acquisition by the plant roots. The current study highlights the role that soil geochemical factors play in influencing Cd uptake by hyperaccumulating plants. While these plants may have high physiological potential to accumulate metals from contaminated soils, individual soil geochemical factors and the plant-soil interactions in that soil will dictate the actual amount of phytoextractable metal. This underlines the need for site-specific understanding of metal-containing solid phases and geochemical properties of soils before undertaking phytoextraction efforts. [ABSTRACT FROM AUTHOR]

Chemically synthesized nanoparticles (NPs) are widely used in industry and concern over their impact on the environment is rising. In this study, greenhouse grown bean ( Phaseolus vulgaris L.) plants were treated with CeO 2 NPs suspensions at 0, 250, 500, 1000, and 2000 mg L − 1 either aerially by spraying or via soil application. At 15 days after treatment, plants were analyzed for Ce uptake, morphological and biochemical assays, as well as high-resolution mass spectrometry based metabolomics and proteomics. The results from ICP-MS assays showed a dose dependent absorption, uptake and translocation of Ce through both roots and leaves; Ce content increased from 0.68 up to 1894 mg kg − 1 following spray application, while concentrations were three orders lower following soil application (0.59 to 2.19 mg kg − 1 ). Electrolyte leakage increased with NPs rate, from 25.2% to 70.3% and from 24.8% to 32.9% following spray and soil application, respectively. Spraying lowered stomatal density (from 337 to 113 per mm 2 ) and increased stomatal length (from 12.8 to 19.4 μm), and altered photosynthesis and electron transport chain biochemical machinery. The increase in Ce content induced accumulation of osmolites (proline increased from 0.54 to 0.65 mg/g under spray application), phytosiderophores (muconate and mugineate compounds showed increase fold-changes > 16) and proteins involved in folding or turnover. NPs application induced membrane damage, as evidenced by the increase in membrane lipids degradates and by the increase in electrolyte leakage, and caused oxidative stress. Most of the responses were not linear but dose-dependent, whereas metabolic disruption is expected at the highest NPs dosage. Both proteomics and metabolomics highlighted a stronger effect of CeO 2 NPs spraying, as compared to soil application. High concentrations of NPs in the environment have been confirmed to pose toxicity concern towards plants, although important differences could be highlighted between aerial deposition and soil contamination. [ABSTRACT FROM AUTHOR]

Mining activities lead to widespread environmental pollution of terrestrial ecosystems due to the presence of metal(loid)s in tailings. These contaminated areas present a health risk and hence need to be rehabilitated. Ex situ methods for soil remediation have been used for a long time but are expensive and disruptive to soil. Phytoremediation techniques for the stabilization or extraction of metal(loid)s could be an efficient alternative as they provide a low-cost and environmentally friendly option. However, due to the often poor nutrient content of these contaminated soils, amendments must be added to enhance plant growth and to improve phytoremediation efficiency. Biochar, a pyrogenic product, is a promising amendment for assisted phytoremediation. The aims of our study were (i) to evaluate the effect of a pinewood biochar on the physicochemical properties of a former mine contaminated technosol, (ii) to assess the mobility and phytoavailability of As and Pb and (iii) to investigate the remediation potential of three willow species ( Salix alba , Salix viminalis and Salix purpurea ). A greenhouse experiment was conducted with contaminated technosols amended with biochar and garden soil, single or combined, revegetated with the 3 willow species. The physicochemical properties of soil pore water (SPW) as well as metal(loid) concentrations were determined. Plant growth, Salix organ dry weight and metal(loid) uptake were determined in order to evaluate the phytoremediation potential of the three Salix species studied. Biochar increased the pH and electrical conductivity of SPW. Biochar addition had no effect on As mobility but decreased SPW Pb concentration by 70%. For the three Salix species investigated, biochar addition to the polluted soil induced a better growth and a higher dry weight production. In most modalities tested, the metal(loid) content in the Salix organs increased due to the biochar application. Globally, a positive effect of biochar was noticed on the soil qualities (pH and electrical conductivity increase) and plant growth. Metal(loid)s were mostly confined to the roots. Among the species tested, Salix alba presented the lowest metal(loid) concentrations in the aerial parts, making it a particularly suitable tool for Pb soil phytostabilization. [ABSTRACT FROM AUTHOR]

Soils contaminated with heavy metals are often notably nutrient poor and unsuitable for plant growth. The addition of biochar can significantly improve soil properties. In this study, the contents of organic compounds and inorganic elements in biochar and the effect of biochar on plant germination were examined. The PAH content of biochar from four different sources was examined, and naphthalene, phenanthrene, fluoranthene and pyrene were identified as primary compounds. The most abundant inorganic elements were potassium, calcium, magnesium, sodium, aluminium, iron and manganese, with strontium and barium also being significantly elevated. The pH of biochar from all sources was strongly alkaline. The sorption characteristics for heavy metals (Cd, Cu and Pb) were also tested for the different types of biochar. Adsorption data were well-described by a Langmuir isotherm with maximum Cd (II), Cu (II) and Pb (II) adsorption capacities of 20.16, 7.83 and 70.92 mg/g for bamboo-derived biochar; 18.80, 13.85 and 200 mg/g for rice husk-derived biochar; 11.63, 20.08 and 123.46 mg/g for ash tree-derived biochar; and 15.11, 10.86 and 196.08 mg/g for beech tree-derived biochar, respectively. The effect of biochar on the toxicity of heavy metals was measured by the inhibition of sorghum seed germination. With biochar, the toxicity of cadmium, copper and lead was reduced. Bamboo-derived biochar was less efficient in reducing the toxicity of cadmium and copper compared with the other types of biochar. For lead, the rice husk-derived biochar was the least efficient in reducing the toxicity. [ABSTRACT FROM AUTHOR]

Soil contamination with persistent and potentially (eco)toxic heavy metal(loid)s is ubiquitous around the globe. Concentration of these heavy metal(loid)s in soil has increased drastically over the last three decades, thus posing risk to the environment and human health. Some technologies have long been in use to remediate the hazardous heavy metal(loid)s. Conventional remediation methods for heavy metal(loid)s are generally based on physical, chemical and biological approaches, which may be used in combination with one another to clean-up heavy metal(loid) contaminated soils to an acceptable and safe level. This review summarizes the soil contamination by heavy metal(loid)s at a global scale, accumulation of heavy metal(loid)s in vegetables to toxic levels and their regulatory guidelines in soil. In this review, we also elucidate and compare the pool of available technologies that are currently being applied for remediation of heavy metal(loid) contaminated soils, as well as the economic aspect of soil remediation for different techniques. This review article includes an assessment of the contemporary status of technology deployment and recommendations for future remediation research. Finally, the molecular and genetic basis of heavy metal(loid) (hyper)accumulation and tolerance in microbes and plants is also discussed. It is proposed that for effective and economic remediation of soil, a better understanding of remediation procedures and the various options available at the different stages of remediation is highly necessary. [ABSTRACT FROM AUTHOR]

Phytoextraction of arsenic (As) from contaminated soil using hyperaccumulator Pteris vittata L. has been applied to several contaminated areas in China and USA; however, most of them are located in Southern China. Low temperature during winter is the main reason limiting the application of P. vittata in Northern China. The aim of the current study is to explore the possibility of using P. vittata to remediate As-contaminated soil in Northern China and other areas with similar climate conditions and to obtain appropriate measures to aid in the survival of P. vittata in winter. Four different cover materials were used in the current study; by comparing growth conditions and remediation efficiency, the most suitable cover material for P. vittata was obtained. Results showed that using the combination of plastic film and soil or maize straw significantly improved soil temperature. While, the use of a single layer plastic film was the best choice when considering As accumulation. [ABSTRACT FROM AUTHOR]

The exploitation of the association between plants and microorganisms is a promising approach able to boost natural attenuation processes for soil clean-up in vast polluted areas characterized by mixed chemical contamination. We aimed to explore the selection of root-associated bacterial communities driven by different plant species spontaneously established in abandoned agricultural soils within a historical polluted site in north Italy. The site is highly contaminated by chlorinated persistent organic pollutants, mainly constituted by polychlorobiphenyls (PCBs), together with heavy metals and metalloids, in variable concentrations and uneven distribution. The overall structure of the non-vegetated and root-associated soil fractions bacterial communities was described by high-throughput sequencing of the 16S rRNA gene, and a collection of 165 rhizobacterial isolates able to use biphenyl as unique carbon source was assayed for plant growth promotion (PGP) traits and bioremediation potential. The results showed that the recruitment of specific bacterial communities in the root-associated soil fractions was driven by both soil fractions and plant species, explaining 21 and 18% of the total bacterial microbiome variation, respectively. PCR-based detection in the soil metagenome of bacterial bphA gene, encoding for the biphenyl dioxygenase a subunit, indicated that the soil in the site possesses metabolic traits linked to PCB degradation. Biphenyl-utilizing bacteria isolated from the rhizosphere of the three different plant species showed low phylogenetic diversity and well represented functional traits, in terms of PGP and bioremediation potential. On average, 72% of the strains harbored the bphA gene and/or displayed catechol 2,3-dioxygenase activity, involved in aromatic ring cleavage. PGP traits, including 1-aminocyclopropane-1-carboxylic acid deaminase activity potentially associated to plant stress tolerance induction, were widely distributed among the isolates according to in vitro assays. PGP tested in vivo on tomato plants using eleven selected bacterial isolates, confirmed the promotion and protection potential of the rhizosphere bacteria. Different spontaneous plant species naturally selected in a historical chronically polluted site showed to determine the enrichment of peculiar bacterial communities in the soil fractions associated to the roots. All the rhizosphere communities, nevertheless, hosted bacteria with degradation/detoxification and PGP potential, putatively sustaining the natural attenuation process. [ABSTRACT FROM AUTHOR]

Secondary metabolites, which have an important role in regulating plants' relationship with the environment, are affected by soil pollution. Thus, it is important to describe the mechanism in which lemon balm's (Melissa officinalis L. subsp. officinalis) secondary metabolite accumulation is affected by Cadmium (Cd) stress. For this purpose, lemon balms seedlings that were grown in a controlled environment were exposed to increasing Cd stress and the relationship of lemon balm's growth and development with EO (essential oil) accumulation were investigated. Morphological, anatomical and physiological parameters of plants' that were exposed to Cd significantly decreased in parallel with increasing Cd concentration. Impairments in growth and development of lemon balm due to increasing Cd concentrations also affected EO accumulation. However, this destructive effect was most evident on EO accumulation amongst all investigated parameters. Furthermore, amount of EO decreased by 97%, at the highest concentration. In conclusion, Cd might have damaged both the EO producing mechanism and the structures that produce EO by inhibiting plant growth. Therefore it is important to reveal the responses of all parameters which affect EO production of medicinal plants under various stress conditions. [ABSTRACT FROM AUTHOR]

Background and aims: Contaminated soils can impede germination and growth of selected plant species, restricting effective phytoremediation strategies. The purpose of the present study was to enhance the germination and growth of saltgrass [ Distichlis spicata (L.) Greene] by evaluating the efficacy of certain seed pretreatments and soil amendments. Methods: Ten seed pretreatment methods, two amendments, three soil depths and five saline levels were tested under greenhouse conditions. Results: Saltgrass germination and growth were negatively correlated with increasing salinity levels when NaCl > 85.6 mM. Among ten seed pretreatments (stratification + Proxy 24 h, hot water + Proxy 24 h, stratification, hot water + Proxy 48 h, Proxy 48 h, Proxy 24 h, hot water, scarification, gibberellins, and KMnO), the two best methods were stratification + Proxy 24 h and hot water + Proxy 24 h for enhancing saltgrass germination, with the latter pretreatment being especially useful because of its shorter preparation time and high germination rates. Proxy is a commercial ethephon product. Potting soil (5.0 cm depth) was found to be the best amendment for saltgrass germination and growth in hydrocarbon-contaminated soils. Conclusion: We conclude that direct seeding of saline soils contaminated with petroleum hydrocarbons is a feasible phytoremediation strategy provided that appropriate seed pretreatments and amendments are utilized. [ABSTRACT FROM AUTHOR]

Sulphur (S) deficiency, cadmium (Cd) toxicity and their combinations are of wide occurrence throughout agricultural lands. We assessed the impact of short-term (2 days) and long-term (4 days) applications of cadmium (40 μg/g soil) on spinach plants grown on sulphur-sufficient (300 μM SO ) and sulphur-deficient (30 μM SO ) soils. Compared with the control (+S and −Cd), oxidative stress was increased by S deficiency (−S and −Cd), cadmium (+S and +Cd) and their combination stress (−S and +Cd) in the order of (S deficiency) < (Cd stress) < (S deficiency and +Cd stress). SDS-PAGE profile of leaf proteins showed a high vulnerability of rubisco large subunit (RbcL) to S deficiency. Rubisco small subunit (RbcS) was particularly sensitive to Cd as well as dual stress (+Cd and −S) but increased with Cd in the presence of S. Cysteine content in low molecular weight proteins/peptide was also affected, showing a significant increase under cadmium treatment. Components of ascorbate-glutathione antioxidant system altered their levels, showing the maximum decline in ascorbate (ASA), dehydroascorbate (DHA), total ascorbate (ASA + DHA, hereafter TA), glutathione (GSH) and total glutathione (GSH + GSSG, hereafter TG) under S deficiency. However, total ascorbate and total glutathione increased, besides a marginal increase in their reduced and oxidized forms, when Cd was applied in the presence of sufficient S. Sulphur supply also helped in increasing the activity of superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR) and catalase (CAT) under Cd stress. However, their activity suffered by S deficiency and by Cd stress during S deficiency. Each stress declined the contents of soluble protein and photosynthetic pigments; the highest decline in contents of protein and pigments occurred under S deficiency and dual stress respectively. The fresh and dry weights, although affected adversely by every stress, declined most under dual stress. It may be concluded that an optimal level of S is required during Cd stress for better response of SOD, APX, GR and CAT activity, as well as synthesis of cysteine. RbcS is as highly sensitive to S deficiency as RbcL is to Cd stress. [ABSTRACT FROM AUTHOR]

The roadside habitat can be challenging for plants, which must maintain normal biological processes despite an influx of airborne pollutants. While the effects of many gases on plants have been quantified, the impacts of particulate pollutants have been relatively less studied. This is especially true of field experiments where particle dispersion may be influenced by meteorology and roadway use. We examined chicory ( Cichorium intybus L.) along roadsides in the Cincinnati, Ohio metropolitan area to assess particulate influence on plant pollination through stigmatic clogging. We compared flowers collected from plants situated along interstates, U.S. highways, state highways, and county roads as these different road-types vary in motor vehicle usage and thus should have varying levels of particulate deposition on flowers. We examined floral stigmas for total particulates, total pollen, and percentage of pollen tube germination to determine whether particulates may interfere with early reproductive processes. Our results suggest that there was minimal variation of particulate matter found on chicory stigmas among road-types. Furthermore, the deposition of particulates on stigmas based on road-type did not show a strong link to variation in pollen deposition and pollen germination. There was also no significant relationship between total particulate levels and pollen germination rates across all road types. Future studies should investigate other plant species that may be more sensitive to roadside pollution, such as economically important crops. Locations in which vehicle use is increasing and where pollutants are not regulated strictly should also be examined as the effects of airborne particulates in early plant reproduction would be expected to be more substantial in these areas. [ABSTRACT FROM AUTHOR]

Pharmaceutical and personal care products (PPCPs) are continuously introduced into the soil-plant system, through practices such as agronomic use of reclaimed water and biosolids containing these trace contaminants. Plants may accumulate PPCPs from soil, serving as a conduit for human exposure. Metabolism likely controls the final accumulation of PPCPs in plants, but is in general poorly understood for emerging contaminants. In this study, we used diclofenac as a model compound, and employed 14 C tracing, and time-of-flight (TOF) and triple quadruple (QqQ) mass spectrometers to unravel its metabolism pathways in Arabidopsis thaliana cells. We further validated the primary metabolites in Arabidopsis seedlings. Diclofenac was quickly taken up into A. thaliana cells. Phase I metabolism involved hydroxylation and successive oxidation and cyclization reactions. However, Phase I metabolites did not accumulate appreciably; they were instead rapidly conjugated with sulfate, glucose, and glutamic acid through Phase II metabolism. In particular, diclofenac parent was directly conjugated with glutamic acid, with acyl-glutamatyl-diclofenac accounting for >70% of the extractable metabolites after 120-h incubation. In addition, at the end of incubation, >40% of the spiked diclofenac was in the non-extractable form, suggesting extensive sequestration into cell matter. The rapid formation of non-extractable residue and dominance of diclofenac-glutamate conjugate uncover previously unknown metabolism pathways for diclofenac. In particular, the rapid conjugation of parent highlights the need to consider conjugates of emerging contaminants in higher plants, and their biological activity and human health implications. [ABSTRACT FROM AUTHOR]

Understanding the phytoavailability of bound residues of polycyclic aromatic hydrocarbons (PAHs) in soils is essential to assessing their environmental fate and risks. This study investigated the release and plant uptake of bound PAH residues (reference to parent compounds) in field contaminated soils after the removal of extractable PAH fractions. Plant pot experiments were performed in a greenhouse using ryegrass ( Lolium multiflorum Lam.) to examine the phytoavailablility of bound PAH residues, and microcosm incubation experiments with and without the addition of artificial root exudates (AREs) or oxalic acid were conducted to examine the effect of root exudates on the release of bound PAH residues. PAH accumulation in the ryegrass after a 50-day growth period indicated that bound PAH residues were significantly phytoavailable. The extractable fractions, including the desorbing and non-desorbing fractions, dominated the total PAH concentrations in vegetated soils after 50 days, indicating the transfer of bound PAH residues to the extractable fractions. This transfer was facilitated by root exudates. The addition of AREs and oxalic acid to test soils enhanced the release of bound PAH residues into their extractable fractions, resulting in enhanced phytoavailability of bound PAH residues in soils. This study provided important information regarding environmental fate and risks of bound PAH residues in soils. [ABSTRACT FROM AUTHOR]

Salix schwerinii was tested in a pot experiment to assess plant growth performance i.e., relative height and dry biomass and the potential for heavy metal uptake in soils polluted with chromium, zinc, copper, nickel and total petroleum hydrocarbons. The soil used in the pot experiment was collected from a landfill area in Finland. Peat soil was added at different quantities to the polluted soil to stimulate plant growth. The plants were irrigated with tap water or processed water (municipal waste water) to further investigate the effects of nutrient loading on plant biomass growth. The soil was treated at two pH levels (4 and 6). The results showed that the addition of 40–70% peat soil at pH 6 to a polluted soil, and irrigation with processed water accelerated plant growth and phytoextraction efficiency. In the pot experiment, Salix grown in chromium, zinc, copper, nickel and total petroleum hydrocarbons -contaminated field soil for 141 days were unaffected by the contaminated soil and took up excess nutrients from the soil and water. Total mean chromium concentration in the plant organs ranged from 17.05 to 250.45 mg kg −1 , mean zinc concentration ranged from 142.32 to 1616.59 mg kg −1 , mean copper concentration ranged from 12.11 to 223.74 mg kg −1 and mean nickel concentration ranged from 10.11 to 75.90 mg kg −1 . Mean chromium concentration in the plant organs ranged from 46 to 94%, mean zinc concentration ranged from 44 to 76%, mean copper concentration ranged from 19 to 54% and mean nickel concentration ranged from 8 to 21% across all treatments. Under the different treatments, chromium was taken up by Salix in the largest quantities, followed by zinc, copper and nickel respectively. Salix also produced a moderate reduction in total petroleum total petroleum hydrocarbons in the polluted soil. The results from the pot experiment suggest that Salix schwerinii has the potential to accumulate significant amounts of chromium, zinc, copper and nickel. However, long term research is needed to verify the phytoextraction abilities of Salix observed in the pot experiment. [ABSTRACT FROM AUTHOR]

Informal recycling of e-waste and the resulting heavy metal pollution has become a serious burden on the ecosystem in Guiyu, China. In this investigation, we evaluated the trace metal concentration of community soil and road dust samples from 11 locations in Guiyu and 5 locations (consisting of residential areas, kindergarten/school, and farm field) in a reference area using graphite furnace atomic absorption spectrophotometer. The study spanned four seasons, 2012-2013, with a view to assess the risk associated with e-waste recycling in the study area. The concentrations of Pb, Cd, Cr, and Mn were 448.73, 0.71, 63.90, and 806.54 mg/kg in Guiyu soil and 589.74, 1.94, 69.71, and 693.74 mg/kg, in the dust, respectively. Pb and Cd values were significantly higher ( P ≤ 0.05) than the reference area, and the mixed model analysis with repeated seasonal measurements revealed soil Pb and Cd levels that were 2.32 and 4.34 times, while the ratios for dust sample were 4.10 and 3.18 times higher than the reference area. Contamination factor, degree of contamination, and pollution load index indicated that all sampling points had a high level of metal contamination except farm land and kindergarten compound. The cumulative hazard index of Pb, Cd, Cr, and Mn for children in exposed area was 0.99 and 1.62 for soil and dust, respectively, suggesting non-cancer health risk potential. The significant accumulation of trace metals in the e-waste recycling area predisposes human life, especially children, to a potentially serious health risk. [ABSTRACT FROM AUTHOR]

In this study, we aimed to confirm that indole-3-acetic acid promotes plant uptake of phenanthrene (PHE), stimulates the activity of soil enzymes or microflora, and thereby accelerates the dissipation of PHE in soil. Four treatments were evaluated: PHE-contaminated soil planted with (1) ryegrass (T0), (2) ryegrass and supplemented with 1 mg kg indole-3-acetic acid (IAA) (T1), (3) ryegrass and supplemented with 5 mg kg IAA (T5), and (4) ryegrass and supplemented with 10 mg kg IAA (T10). After 30 days, PHE concentrations were lower for all treatments and the removal rate was 70.19, 89.17, 91.26, and 97.07 % for T0, T1, T5, and T10, respectively. PHE was only detected in the roots and not in the shoots. IAA facilitated the accumulation of PHE in the roots, and plants subjected to the T10 treatment had the highest levels. Exogenous IAA stimulated soil peroxidase activity in a dose-dependent manner, whereas soil polyphenoloxidase activity was not significantly increased, except in T10. Soil microbial biomass also increased in response to IAA treatment, particularly in T10. Furthermore, phospholipid fatty acid analysis showed that IAA treatment increased microbial biomass and alleviated environmental stress. Gram-positive bacteria are largely responsible for polycyclic aromatic hydrocarbon degradation, and we found that the ratio of gram-positive to gram-negative bacteria in the soil significantly increased as the IAA concentrations increased ( P < 0.05). Correlation analysis indicated that the increase in soil microbial biomass, enzyme activity, and plant uptake of PHE promotes removal of PHE from the soil. [ABSTRACT FROM AUTHOR]

This paper analyses the capacity of the rape ( Brassica napus) to extract Cd and Zn from the soil and the effect of these metals on the morphometric parameters of the plant (length, weight, surface area, fractal dimension of leaves). Rape plants were mostly affected by the combined toxicity of the Cd and Zn mixture that caused a significant reduction in the rate of seed germination, the plant biomass quantity and the fractal dimension. In the case of Cd soil pollution, the bioaccumulation factor (BAF), bioaccumulation coefficient (BAC) as well as the heavy metal root-to-stalk translocation factor (TF) were determined. The results showed that B. napus had a great potential as a cadmium hyperaccumulator but not as an accumulator of Zn or Cd + Zn mixture. The efficiency of phytoextraction rape was 0.8-1.22 % for a soil heavily polluted with cadmium. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium hirsutumL.) is a well-known and economically most beneficial crop worldwide while nickel (Ni) toxicity is a widespread problem in crops grown on Ni-contaminated soils. We investigated the response of silicon (Si) in cotton under Ni stress with respect to growth, biomass, gas exchange attributes, enzymatic activities, and Ni uptake and accumulation. For this, plants were grown in hydroponics for 12 weeks with three levels of Ni (0, 50, and 100 µM) in the presence or absence of 1 mM Si. Results showed that Ni significantly reduced the plant growth, biomass, gas exchange attributes, and pigment contents while Si application mitigated these adverse effects under Ni stress. Nickel stress significantly decreased antioxidant enzymes’ activities while increased malondialdehyde (MDA), hydrogen peroxide (H2O2), and electrolyte leakage (EC) in leaves and roots. The application of Si enhanced the activities of antioxidant enzymes and reduced MDA, H2O2, and EC in plants. Nickel application significantly increased Ni concentration and accumulation in leaf, stem, and roots while Si application significantly decreased Ni in these plant parts. The present study indicates that Si could improve cotton growth under Ni stress by lowering Ni uptake and reactive oxygen species (ROS) and by increasing antioxidant enzymes activities. [ABSTRACT FROM AUTHOR]

This study determined the fate of triclosan, a prevalent wastewater contaminant in recycled waters and surface streams, when soil and crop plants were irrigated at environmentally relevant concentrations. Soil triclosan concentrations were monitored in an 8-wk and in a 16-wk study without plants to determine triclosan degradation. Onion (Allium oschaninii O. Fedtsch.) and tomato (Solanum lycopersicum L.) were assessed for growth and triclosan accumulation at four levels of triclosan exposure (0, 0.015, 0.15, and 1.5 µg L-1) in irrigation waters within ranges of those found in recycled waters and associated receiving streams. Onions were grown for 8 wk and tomatoes were grown for 8 wk (short-term study) and 12 wk (long-term study) in potting soil. Soil triclosan concentrations increased (5-fold) with triclosan levels applied to soils alone. With repeated application, the half-life of triclosan was 18 d, with low-level accumulation in soil. Bioaccumulation of triclosan was observed in all edible portions of onions (115-435 ng g-1), primarily in bulbs, with no discernible impact on biomass. In both short- and long-term tomato studies, triclosan translocated to shoots and fruits (approaching a translocation factor of 1) at the highest level examined. Even at low triclosan concentrations typically found in recycled waters and receiving streams, agricultural irrigation presents an additional exposure route for organic contaminants to humans via commercial crops. Our study indicates that bulb crops, in particular, would likely accumulate high levels of triclosan. However, concentrations detected in both onions and tomato fruits determined here are below current human exposure limits. [ABSTRACT FROM AUTHOR]

The present study investigates the impact of the nanoremediation treatment on soil recovery as evaluated by the development of barley plants. Highly As-polluted brownfield soil was treated with nanoscale zero-valent iron (nZVI) commercial suspension at two doses (1% and 10%). Barley plants were cultivated in treated and untreated soils in a growth chamber, and the As, Fe, and nutrients uptake were determined. The efficacy of As immobilization was evaluated according to the toxicity characteristics leaching procedure (TCLP) as well as using a sequential extraction procedure. The application of nZVI reduced the amount of As in the more available fractions and increased the amount of As in the residual fraction. The best immobilization results were obtained for the highest dose of nZVI (10%). In turn, the lower availability of As in nZVI-treated soils, particularly at the dose of 10%, stimulated the development of the barley plants and decreased the As uptake. Neither an important increase of available Fe nor negative impact on soil physico-chemical and biological properties were observed. Thus, our results show that the use of nZVI could be an adequate strategy to recover the land use in As polluted soils. [ABSTRACT FROM AUTHOR]

Reliable empirical models describing lead (Pb) transfer in soil-plant systems are needed to improve soil environmental quality standards. A greenhouse experiment was conducted to develop soil-plant transfer models to predict Pb concentrations in carrot ( Daucus carota L.). Soil thresholds for food safety were then derived inversely using the prediction model in view of the maximum allowable limit for Pb in food. The 2 most important soil properties that influenced carrot Pb uptake factor (ratio of Pb concentration in carrot to that in soil) were soil pH and cation exchange capacity (CEC), as revealed by path analysis. Stepwise multiple linear regression models were based on soil properties and the pseudo total (aqua regia) or extractable (0.01 M CaCl2 and 0.005 M diethylenetriamine pentaacetic acid) soil Pb concentrations. Carrot Pb contents were best explained by the pseudo total soil Pb concentrations in combination with soil pH and CEC, with the percentage of variation explained being up to 93%. The derived soil thresholds based on added Pb (total soil Pb with the geogenic background part subtracted) have the advantage of better applicability to soils with high natural background Pb levels. Validation of the thresholds against data from field trials and literature studies indicated that the proposed thresholds are reasonable and reliable. Environ Toxicol Chem 2015;34:2078-2086. © 2015 SETAC [ABSTRACT FROM AUTHOR]

The problem of copper (Cu) pollution in riverine ecosystems is world-wide and has significant environmental, eco-toxicological, and agricultural relevance. We assessed the suitability and effectiveness of application rate of 1% of activated charcoal, bentonite, biochar, cement kiln dust, chitosan, coal fly ash, limestone, nano-hydroxyapatite, organo-clay, sugar beet factory lime, and zeolite as soil amendments together with rapeseed as bioenergy crop as a possible remediation option for a heavily Cu polluted floodplain soil (total Cu=3041.9 mg kg −1 ) that has a very high proportion of sorbed/carbonate fraction (484.6 mg kg −1 ) and potential mobile fraction of Cu (1611.9 mg kg −1 ). Application changed distribution of Cu among geochemical fractions: alkaline materials lead to increased carbonate bounded fraction and the acid rhizosphere zone might cause release of this Cu. Thus, mobilization of Cu and uptake of Cu by rapeseed were increased compared to the control (except for organo-clay) under the prevailing conditions. [ABSTRACT FROM AUTHOR]

Copper bioavailability, specially to plants, is strongly dependent on its chemical form, as for most metals. Copper-contaminated soil can be treated in situ by the addition of minerals such as Na-bentonite, which mixed with surface soil, can transform this pollutant to non-bioavailable forms. In this work, shelter experiments were conducted to study the time evolution of Cu speciation, in pristine soil as well as in amended one. A selective sequential extraction method was employed to determine the metal speciation in the samples. The results show that the major metal fraction is the organic matter-bound one, whereas the exchangeable fraction is very low, even the first day after Cu addition. The time evolution shows a slow decrease of the organic-bound Cu and a corresponding increase of the most stable mineral fractions. With the addition of Na-bentonite to copper-contaminated soil, the most stable mineral fractions increase whereas the organic-bound one decreases, showing essentially similar time dependence of the several metal fractions. Sodium bentonite could be effectively used for remediation of soils polluted with Cu. [ABSTRACT FROM AUTHOR]

Reclaimed water is an important source of irrigation and is widely used on agricultural soils throughout the world, particularly in arid and semi-arid regions. However, concerns about the potential risks of this practice are rapidly increasing because reclaimed water may contain various organic pollutants such as pharmaceuticals and personal care products (PPCPs). Trace levels of PPCPs have been found in fields irrigated with reclaimed water, and continual infusion, along with bioaccumulation properties, may result in significant bio-uptake and PPCP contamination in agricultural soils. This review attempts to summarize the literature concerning the fate and behavior of PPCPs in agricultural soils, as well as their adverse effects on soil organisms (including microorganisms and fauna), crops, and even humans via dietary consumption. Strategies and potential technologies for degrading or removing PPCPs from soils are addressed, along with the irrigation strategies and agricultural practices for minimizing PPCP transfer to crops and groundwater. Based on this review, we conclude that the agricultural risks of PPCPs associated with reclaimed water irrigation could be controlled under certain agro-ecological conditions. We suggest developing agro-ecosystem-specific practices and regulations for reclaimed water irrigation on the basis of a systematic assessment and modeling analysis of the fate, transport, accumulation, and transformation of PPCPs in soil–crop systems. [ABSTRACT FROM PUBLISHER]

Atractylis serratuloides is an abundant native spiny species that grows in the surroundings of superphosphate factories in Tunisia. This plant species is adapted to arid environments and tolerates a high level of fluoride pollution in soils. The aim of this study was to better understand the physiological mechanisms of fluoride tolerance of this species, comparing the fluoride-contaminated sites of Gabes and Skhira with the reference site of Smara. Results demonstrated the involvement of leaf element and phytometabolite balances in the in situ response of A. serrulatoides to fluoride. Calcium, sulphur and magnesium were differently distributed between the sites of Gabes and Smara in all plant organs. No specific tissue fluorine accumulation in root, stem and leaf, even in the most contaminated site at Gabes, was detected by EDAX mapping. Lower anthocyan and flavonol levels but enhanced nitrogen balance index were found in A. serrulatoides leaves from Gabes compared to the two other sites. A. serratuloides appeared as a fluoride excluder and its tolerance involved calcium interactions with fluoride. Moreover, an occurrence of dark septate endophytes and arbuscular mycorhizal fungi in root systems of A. serratuloides was reported for the first time, and these symbioses were present but low at all sites. We suggest the use of this plant species for fluoride-polluted soil stabilization. [ABSTRACT FROM AUTHOR]

Background and aims: Copper is one of the most important pollutants in mine-contaminated soils. This study tests the response in a sensitive population vs a tolerant one of the model species Silene paradoxa in order to understand the general mechanisms of tolerance at the micromorphological and ultrastructural level. Methods: Two populations of Silene paradoxa were grown in hydroponics and exposed to different CuSO treatments. The roots were investigated with light, fluorescence and transmission electron microscope. Callose and lignin were spectrophotometrically determined. Results: The tolerant population constitutively possessed a higher amount of mucilage and was able to reduce the length of the zone between the apex and the first lignified tracheids. Callose production decreased. It did not show remarkable copper-induced ultrastructural modifications, apart from the presence of precipitates in the tangential walls. The sensitive population showed huge nucleoli with a spongy periphery in the central cylinder together with the presence of electrondense granules in the mitochondria. Plastids were rarely observed and generally very electrondense and elongated. Conclusions: n the copper tolerant population of S. paradoxa some of the root traits concurring to generate metal-excluding roots were suggested to be mucilage and lignin production and the reduction of the subapical root zone. [ABSTRACT FROM AUTHOR]

Romanian agriculture current realities indicates that organized societies with modern equipment and staffed with specialists represent only 20% of the actors in the production, the remaining of 80% being producers with different levels of equipment and staffing specialist. Therefore there are real risks that the inputs used in agriculture (fertilizers, pesticides, etc.) have negative secondary effects (DUMITRU, 2002) through soil and water pollution (GAVRILESCU, 2011). Increased content of nitrates and nitrites in soil and water has become a major factor affecting the health of the population, both rural and urban, and especially children, but in a broader context the entire population consuming water, vegetables fruit from out of control locations (nitrates vulnerable zones) (NAZARYUK et al., 2002). This paper presents the case of illness in children internees at No. 1 Hospital from Craiova for a period of 5 years. One can observe that most cases come from rural areas, 76%, with children aged less than one year and over five years, by introducing in their diet milk powder, tea, soup of carrots and other vegetables that are high in nitrates. Cases have been reported in some villages that were connected to the water system of the village and which were infested with toxic substances. In urban areas the percentage is 24% of illness, it is strongly recommended for measures to limit the content of toxic substances in groundwater and surface water. [ABSTRACT FROM AUTHOR]

Crop root residues are an important source of soil organic carbon (SOC) in arable systems. However, the spatial distribution of root biomass in arable systems remains largely unknown. In this study, we determined the spatial distribution of macro-root and shoot biomass of winter wheat at shoulderslope and footslope positions from four cultivated slopes within an arable field in western Denmark. In addition, soils from the shoulderslope and footslope positions of four slopes were characterized for physical and chemical properties. Root biomass dry matter (DM) was marginally higher ( P = 0.06) at footslope (1.2 Mg DM ha - 1 ) than at shoulderslope positions (0.9 Mg DM ha − 1 ), in particular in the subsoil. Likewise shoot biomass was higher ( P = 0.03) at footslope (10.3 Mg DM ha − 1 ) compared to shoulderslope (7.1 Mg DM ha − 1 ) positions. Soil bulk density increased with depth at shoulderslope positions, but was more variable with depth at footslope positions. Root C was significantly correlated with SOC in shoulderslope soils ( r = 0.98), but not in footslope soils. We conclude that, at shoulderslope positions, SOC originated mainly from root residues whereas at footslope positions, SOC was derived from both root residues and likely soil redistribution processes. Management practices that increase C input at shoulderslope positions potentially enhance soil carbon storage and increase crop productivity, which would probably not be the case for C rich footslope soils. These findings imply that models used to simulate or predict C dynamics and crop productivity should consider topography-controlled variations in root C input and SOC redistribution as well as their effects on soil properties, root growth and crop productivity. [ABSTRACT FROM AUTHOR]

Chlordecone (CLD), an organochlorine insecticide, and other persistent organic pollutants continue to contaminate the environment worldwide and have adverse effects on human health through food exposure. Cucurbitaceae take up weathered hydrophobic pollutants from the soil and translocate them to their shoots. As Cucurbitaceae are an important part of the diet in the French West Indies, they are among the main contributors to total dietary intake of CLD. We analyzed the contamination by CLDs (CLD and 5b-hydroCLD) of four cucurbits grown in the field and/or in the greenhouse. Different physiological (crop species) and environmental (soil type, growth conditions) variables were shown to influence uptake of the pollutant from the soil by the crop. Cucurbita species (zucchini and pumpkin) were more contaminated than Cucumis sativus (cucumber), and Sechium edule (christophine or chayote) translocated CLDs to fruits very poorly compared with cucumber and pumpkin. Greenhouse conditions and non-allophanic (nitisols and ferralsols) soils favored plant contamination more than field conditions and allophanic soils (andosols). [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) belong to phylum Glomeromycota, an early divergent fungal lineage forming symbiosis with plant roots. Many reports have documented that bacteria are intimately associated with AMF mycelia in the soil. However, the role of these bacteria remains unclear and their diversity within intraradical AMF structures has yet to be explored. We aim to assess the bacterial communities associated within intraradical propagules (vesicles and intraradical spores) harvested from roots of plant growing in the sediments of an extremely petroleum hydrocarbon-polluted basin. Solidago rugosa roots were sampled, surface-sterilized, and microdissected. Eleven propagules were randomly collected and individually subjected to whole-genome amplification, followed by PCRs, cloning, and sequencing targeting fungal and bacterial rDNA. Ribotyping of the 11 propagules showed that at least five different AMF OTUs could be present in S. rugosa roots, while 16S rRNA ribotyping of six of the 11 different propagules showed a surprisingly high bacterial richness associated with the AMF within plant roots. Most dominant bacterial OTUs belonged to Sphingomonas sp., Pseudomonas sp., Massilia sp., and Methylobacterium sp. This study provides the first evidence of the bacterial diversity associated with AMF propagules within the roots of plants growing in extremely petroleum hydrocarbon-polluted conditions. [ABSTRACT FROM AUTHOR]

The effects of the Populus alba tree on different biochemical soil properties, growing in a contaminated area, were studied for two years under field conditions. Two types of trace element contaminated soils were studied: a neutral contaminated soil (NC) and an acid contaminated soil (AC). One neutral non-contaminated area was studied as control. Soil samples were collected at depths of 0–20 cm and 20–40 cm. Leaves and litter samples were analysed. The addition of organic matter, through root exudates and litter, contributed to an increase in soil pH, especially in acid soil. Microbial Biomass Carbon (MBC) was significantly increased by the presence of the trees in all studied areas, especially in the upper soil layer. Similar results were also observed for protease activity. Both MBC and Protease activity were more sensitive to contamination than β-glucosidase activity. These changes resulted in a decrease of available trace element concentrations in soil and in an improvement of soil quality after a 2-year study. The total concentration of Cd and Zn in soil did not increase over time due to litter deposition. Analysis of P. alba leaves did not show a significant nutritional imbalance and trace element concentrations were normal for plants, except for Cd and Zn. These results indicate that P. alba is suitable for the improvement of soil quality in riparian contaminated areas. However, due to the high Cd and Zn concentrations in leaves, further monitoring of this area is required. [Copyright &y& Elsevier]

Abstract: The pollution of agricultural soils with cadmium (Cd) has become a serious problem worldwide. The potato (Solanum tuberosum L.) was used to investigate how different concentrations of Cd (1, 5, and 25mgkg−1) affected the physiological parameters and the subcellular distribution of Cd in the potato. The analyses were conducted using scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX). The results suggest that the leaf is the organ with the highest accumulation of Cd. The malondialdehyde (MDA) content increased and the chlorophyll content decreased in response to high level of Cd. The SEM-EDX microanalysis revealed that Cd was primarily deposited in the spongy and palisade tissues of the leaf. Furthermore, Cd was also detected in the cortex and the adjacent phloem and was observed inside the intercellular space, the interior surface of the plasma membrane, and on the surface of the elliptical starch granules in the tubers of the potato. Although low concentrations of Cd migrated from the root to the tuber, the accumulation of Cd in the tuber exceeded the standard for food security. Therefore, the planting of potato plants in farmland containing Cd should be seriously evaluated because Cd-containing potatoes might present high health risk to humans. [Copyright &y& Elsevier]

The high cost, adverse effects on the environment and low efficiencies of the physical, chemical and thermal techniques currently being used to remediate hydrocarbon contaminated soils calls for evaluation of plant based methods. In this work, phytoremediation study was made with laterite soil artificially contaminated with motor oil. Three replicates of 3 kg of the air dried soil fertilized with 10% (w/w) organic fertilizer were each contaminated with 200ml of motor oil thoroughly mixed and placed in a 35 cm high plastic bowl. Six young plants of sweet potato were transplanted to each of the plastic bowl and allowed eight weeks to grow and stabilize. Hydrocarbon removal from the soil in the presence of the plant species were measured at two weekly intervals for a period of 16 weeks. Our results indicate that sweet potato plant (Ipomoea batatas) can grow, sustain growth and survive in the contaminated soil environment; the plant reduced the initial TPH content in the soil from 75.46mg/g to 19.876mg/g in 16 weeks. It is predicted that it will take about 27 weeks to reduce the TPH content to zero. The study concluded that sweet potato plant (Ipomoea batatas) has potential phytoremediation application in remediating hydrocarbon contaminated soils. [ABSTRACT FROM AUTHOR]

Abstract: The residue of hexachlorocyclohexane (HCH) isomers (mainly α-, β-, γ-, and δ-HCH) in the soils, plant tissues and atmosphere were measured in a typical tea garden in Fujian, a major tea-producing province in China, and this study focused on the distribution and accumulation of HCHs. HCHs could accumulate in most of the plant tissues, with the highest HCH concentration of 3.0±2.9ng/g dw in old leaves. Uptake of HCHs by the roots from soil was the possible pathway for HCHs accumulation in plants, and the accumulation was an isomer-selective process, with the highest concentration factor of 10.3 for α-HCH. The higher percentages of α- and γ-HCH in roots (28.1 percent and 43.7 percent) than those in soil (14.0% and 34.1 percent) also implied the isomer-selective accumulation of HCHs. ΣHCHs in the gaseous phase (157±97pg/m3) were significantly higher than those in particle phase (19±20pg/m3). Volatilization of HCHs from soils and uptake by the plant''s aerial tissues might be the pathway for HCHs accumulation in leaves and stems, and β-HCH showed the highest accumulation capacity in young leaves. The percentage distribution pattern of the dust on plant leaves were similar to that in soils, suggesting that the dust on the leaves were mainly from the soils. High γ-HCH concentrations and low α-/γ-HCH ratios in plant''s aerial tissues suggested the input of lindane in tea garden. [Copyright &y& Elsevier]

Abstract: Heavy metals, in general, can migrate from polluted soil and/or irrigation water to tuber plants, leading, after chronic consumption, to health problems. The scope of this study was to investigate the uptake of chromium and nickel by carrots (Daucus carrota), onions (Allium cepa) and potatoes (Solanum tuberosum) in a greenhouse experiment simulating the open-field irrigation conditions in the two biggest tuber producing regions of Greece (Asopos river in Viotia and Messapia in Evia). The study included cultivation of tubers for a period of approximately 4 months in six irrigation lines, each one provided by a water solution containing different levels of Cr(VI) and Ni(II) ranging from 0μg/l (control) to 250μg/l. The soil used was obtained from a certified organic greenhouse. Uptake of Cr was observed in onion leaves between 0 and 10μg/l water concentrations (+109.2 percent, p=0.006), 0μg/l and 20μg/l (+47.5 percent, p=0.006), 0μg/l and 50μg/l (+202.8 percent, p=0.006), 0μg/l and 100μg/l (+89.9 percent, p=0.028), 0μg/l and 250μg/l (+61.3 percent, p=0.009). Uptake of Ni was observed: (a) in onion leaves between 0 and 250μg/l water concentrations (+90.2 percent, p=0.076), (b) in onion shoots between 0 and 10μg/l (+39.1 percent, p=0.045), 0 and 250μg/l (+55 percent, p=0.047) and (c) in potatoes between 0 and 20μg/l (+28.1 percent, p=0.083). Our results suggest that irrigation water containing Cr and Ni can cross-contaminate onions and potatoes cultivated in a soil never previously polluted, anthropogenically, with heavy metals. No such results were found for carrots. [Copyright &y& Elsevier]

Abstract: Five random vegetable farms were selected to investigate the bioaccumulation risk of heavy metals (HMs) by different type of vegetables around the Pearl River Delta (PRD), China. The concentration order of four major HMs in the surface soil samples was Cd−1) significantly higher than the permissible limit (≤0.3mgkg−1) for agricultural soils. Soil DTPA-extractable (phytoavailable) Cd concentrations differed markedly amongst the five farms, and varied within 0.017–0.17mgkg−1. Meanwhile, 28.0% of vegetable samples collected from these five farms were contaminated with Cd according to the permissible limit (≤0.05mgkg−1), and 71.4% of these polluted samples belonged to stem/leaf vegetables. The average bioaccumulation factors of Cd from cultivated soil to stem/leaf vegetables and melon/fruit/bean vegetables varied within 0.021–0.050 and 0.005–0.020 (soil total Cd basis), and 0.50–2.01 and 0.13–0.53 (soil DTPA-extractable Cd basis), respectively. Redundancy analysis (RDA) showed that DTPA-extractable Cd, which negatively but significantly correlated (P<0.05) to soil pH, was the key factor in influencing vegetable Cd accumulation, notably stem/leaf vegetables. The results show that Cd was the primary metal of risk in vegetable farms around the PRD region, and stem/leaf vegetables posed about 2.2 times higher health risks associated with exposure to Cd than melon/fruit/bean vegetables. [Copyright &y& Elsevier]

Abstract: In order to revegetate an industrial soil polluted by trace metals and metalloids (As, Pb, Cu, Cd, Sb), the impact of pollution on three plant species, Solanum nigrum and Agrostis capillaris, both native species in an industrial site, and Vicia faba, a plant model species, is studied. Following the study of soil pollution from the industrial wasteland of Auzon, it appears that the As is the principal pollutant. Particular attention is given to this metalloid, both in its content and its speciation in the soil that the level of its accumulation in plants. In V. faba and A. capillaris, the trace metals and metalloids inhibit the biomass production and involve a lipid peroxidation in the leaves. Furthermore, these pollutants cause a photosynthesis perturbation by stomatal limitations and a dysfunction of photosystem II. Whatever the plant, the As content is less than 0.1 percent of dry matter, the majority of As absorbed is stored in the roots which play the role of trap organ. In parallel, the culture of S. nigrum decreases significantly the exchangeable and weakly adsorbed fraction of As in rhizospheric soil. This study has highlighted the ability of tolerance to trace metals of S. nigrum and to a lesser extent A. capillaris. Our data indicate that V. faba is not tolerant to soil pollution and is not a metallophyte species. [Copyright &y& Elsevier]

Abstract: Coupling with triolein-embedded cellulose acetate membrane (TECAM) technique, hydroxypropyl β-cyclodextrins (HPCD) extraction method, and the greenhouse pot experiments, the influences of biochars on polychlorinated biphenyls (PCBs) bioavailability in soil to plant (Brassica chinensis L. and Daucus carota) were investigated. Addition of 2% biochars to soils significantly reduced the uptake of PCBs in plant, especially for di-, tri- and tetra-chlorobiphenyls. PCBs concentrations in the roots of B. chinensis and D. carota were reduced for 61.5–93.7%, and 12.7–62.4%, respectively in the presence of biochars. The kinetic study showed that in the soils amended with/without biochars, PCBs concentrations accumulated in TECAM, as well as in the HPCD extraction solution, followed significant linear relationships with those in plant roots. Application of biochars to soil is a potentially promising method to reduce PCBs bioavailability whereas TECAM technique can be a useful tool to predict the bioavailability of PCBs in soil. [Copyright &y& Elsevier]

Abstract: Little is known about the bioaccumulation behavior of polybrominated diphenyl ethers (PBDEs) and other halogenated flame retardants (HFRs) in plants and in herbivores. In the present study, PBDEs and several alternative HFRs (AHFRs) were examined in a small herbivorous food chain (paddy soils–rice plant–apple snails) from an electronic waste recycling site in South China. Mean concentrations of total PBDEs were 40.5, 1.81, and 5.54 ng/g dry weight in the soils, rice plant, and apple snails, respectively. Levels of total AHFRs in the samples were comparable to or even higher than those of PBDEs. The calculated plant to soil concentration ratios for most AHFRs (0.05–3.40) were higher than those for PBDEs (0.02–0.23), indicating the greater bioavailability of the AHFRs in the rice plant. All PBDE congeners and Dechlorane Plus (DP) isomers were biomagnified from the rice plant to apple snails, with mean biomagnification factors (BMFs) of 1.1–5.0. [Copyright &y& Elsevier]

Pipeline systems used to transport petroleum products represent a potential source of soil pollution worldwide. The design of new techniques that may improve current monitoring of pipeline leakage is imperative. This paper assesses the remote detection of small leakages of liquid hydrocarbons indirectly, through the analysis of spectral features of contaminated plants. Leaf and canopy spectra of healthy plants were compared to spectra of plants contaminated with diesel and gasoline, at increasing rates of soil contamination. Contamination effects were observed both visually in the field and thorough changes in the spectral reflectance patterns of vegetation. Results indicate that the remote detection of small volumes of gasoline and diesel contaminations is feasible based on the red edge analysis of leaf and canopy spectra of plants. Brachiaria grass ranks as a favourable choice to be used as an indicator of HCs leakages along pipelines. [Copyright &y& Elsevier]

A pot experiment was conducted to investigate the solubility and redox species of antimony (Sb) in a relocated shooting range soil and its uptake by Lolium perenne L. and Holcus lanatus L. under different water regimes. After 1-week waterlogging, the total Sb concentration in soil solution decreased from ∼110 μg L−1 to <20 μg L−1, and slowly increased over the following 4 weeks, with the dissolution of Fe and Mn (hydr)oxides. In this process, half of the Sb in soil solution was reduced to Sb(III), which greatly affected the plant uptake of Sb. Waterlogging increased shoot Sb concentrations of L. perenne by ∼10 fold but decreased uptake in H. lanatus by 80%. Results indicate that Sb might primarily be taken up as Sb(III) by L. perenne and as Sb(V) by H. lanatus. Temporary waterlogging of soil may increase the risk of trace elements entering the food chain. [Copyright &y& Elsevier]

We used the model organisms Nicotiana tabacum L. cv Xanthi (tobacco) and Triticum aestivum (wheat) to investigate plant uptake of 10-, 30-, and 50-nm diameter Au manufactured nanomaterials (MNMs) coated with either tannate (T-MNMs) or citrate (C-MNMs). Primary particle size, hydrodynamic size, and zeta potential were characterized using transmission electron microscopy (TEM), dynamic light scattering (DLS), and electrophoretic mobility measurements, respectively. Plants were exposed to NPs hydroponically for 3 or 7 days for wheat and tobacco, respectively. Volume averaged Au concentrations were determined using inductively coupled plasma mass spectrometry (ICP-MS). Spatial distribution of Au in tissue samples was determined using laser ablation ICP-MS (LA-ICP-MS) and scanning X-ray fluorescence microscopy (μXRF). Both C-MNMs and T-MNMs of each size treatment bioaccumulated in tobacco, but no bioaccumulation of MNMs was observed for any treatment in wheat. These results indicate that MNMs of a wide range of size and with different surface chemistries are bioavailable to plants, provide mechanistic information regarding the role of cell wall pores in plant uptake of MNMs, and raise questions about the importance of plant species to MNM bioaccumulation. [ABSTRACT FROM AUTHOR]