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... Nevertheless, the implementation of phytoremediation on a commercial scale remains disappointing (Witters et al., 2012a,b). This failure can be related, to some extent, with certain limiting factors of phytoremediation: time constraints, limited budgets, a general absence of long-term perspectives or proper pollution assessments, together with other factors, such as the lack of social concern and information ( Robinson et al., 2003;Scholz and Schnabel, 2006;Lachapelle and Montpetit, 2015;Heckenroth et al., 2016). ...
... Besides the rapid growth and easy acclimation, non-native plants can further become invasive, spreading across the territory and produce large and unpredictable economical costs. A proper and integrated selection of plants for phytoremediation purposes should balance the use of local seedbanks and native plant communities with phytoremediation goals (Heckenroth et al., 2016). Local plants demand less attention, are generally suited to the climate, and do not entail costs or legal problems in terms of seed availability and transportation. ...
... Local plants demand less attention, are generally suited to the climate, and do not entail costs or legal problems in terms of seed availability and transportation. Among others, these reasons led to the fact that preliminary assays using local plant assemblages for phytostabilization in polluted protected areas have been increased (Heckenroth et al., 2016). The possibility of preparing ad hoc mixtures of vegetation with phytoremediation purposes also opens the door to a potential niche in the commercial market. ...
... The presence of elevated concentration of metallic TEs in the soil contributes to (micro)evolutionary changes that have resulted in the development of adaptive traits in plants, enabling them to survive and reproduce in harsh edaphic environments [7,128,129]. Upon time, anthropogenically created metalliferous areas are spontaneously colonized by plant species or specialized ecotypes that occur on both polluted and unpolluted terrains. ...
... The evolution of metal tolerance is accompanied by an increased requirement of tolerant specimens for higher amounts of metal(s) to which they have been adapted, according to Antonovics et al. [131]. It could be reflected in better growth and the development of specimens that are adapted to metalliferous habitats than specimens of the same species, but originating from unpolluted sites during exposition to the same metal level, as observed in Biscutella laevigata [128], Dianthus carthusianorum [132,133], or Armeria maritima [134]. It is also probable that mechanisms of ion detoxification in metal-tolerant plants are so efficient that the threshold of toxicity in these specimens is much higher than in other ones, thus they show growth disturbances later or not at all [135]. ...
... The evolution of metal tolerance is accompanied by an increased 220 requirement of tolerant specimens for higher amounts of metal(s) to which they have been adapted, 221 according to Antonovics et al. [131]. It could be reflected in better growth and the development of 222 specimens that are adapted to metalliferous habitats than specimens of the same species, but originating 223 from unpolluted sites during exposition to the same metal level, as observed in Biscutella laevigata [128], ...
Article
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Heavy metals are an interesting group of trace elements (TEs). Some of them are minutely required for normal plant growth and development, while others have unknown biological actions. They may cause injury when they are applied in an elevated concentration, regardless of the importance for the plant functioning. On the other hand, their application may help to alleviate various abiotic stresses. In this review, both the deleterious and beneficial effects of metallic trace elements from their uptake by roots and leaves, through toxicity, up to the regulation of physiological and molecular mechanisms that are associated with plant protection against stress conditions have been briefly discussed. We have highlighted the involvement of metallic ions in mitigating oxidative stress by the activation of various antioxidant enzymes and emphasized the phenomenon of low-dose stimulation that is caused by non-essential, potentially poisonous elements called hormesis, which is recently one of the most studied issues. Finally, we have described the evolutionary consequences of long-term exposure to metallic elements, resulting in the development of unique assemblages of vegetation, classified as metallophytes, which constitute excellent model systems for research on metal accumulation and tolerance. Taken together, the paper can provide a novel insight into the toxicity concept, since both dose- and genotype-dependent response to the presence of metallic trace elements has been comprehensively explained.
... Recent works that studied the effects of contamination variability on composition and structure of plant communities found correlations between plant assemblages and PTE soil concentrations indicating an alteration of the ecosystem trajectory under pollution pressure 5,[17][18][19] . Plants can deal with small-scale heterogeneity of contaminants by avoiding the most contaminated patches of soil 20 . ...
... Highly contaminated sites also showed a heterogeneous solum PTE contamination with higher levels of industry-related PTE in topsoils. Such a solum PTE distribution trend was previously demonstrated at a local scale by Heckenroth et al. 19 and clearly correlated to the distance to the ruins of the smelter chimney. Our results are also in agreement with those mapped at the scale of the massif of Marseilleveyre 46 demonstrating the effect of wind and uneven relief on PTE dispersion. ...
... The sheer presence of C. juncea on the extremely contaminated Escalette site already demonstrated its tolerance to PTE contamination in a previous study on plant communities 19 . The results of this study highlighted the ability of C. juncea to tolerate contaminants and to grow in a wide range of soil PTE concentrations. ...
Article
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Soil contamination pattern due to industrial activities often leads to high concentrations of potentially toxic elements (PTE) decreasing with depth. This spatial heterogeneity of the soil contamination may have significant consequences on the soil properties and soil living communities. We evaluated the effects of both surface and solum soil contamination heterogeneity on Coronilla juncea L. (Fabaceae) functional traits in field conditions and the phytostabilization potential of this species. Plant and soil samples were collected on 3 sites along a PTE contamination gradient. The correlations between PTE concentration in plant and soil samples at 2 depths, physico-chemical properties of soil, plant biomass and soil microbial activity were tested. Field measurements highlight a decreasing PTE concentration with soil depth in addition to an important surface heterogeneity of As, Cu, Pb, Sb and Zn soil concentrations. Root PTE concentrations in C. juncea did not follow soil PTE concentrations. Concentrations of PTE in the root parts were higher than those of the aerial parts. Low PTE translocation and root symbioses with microorganisms suggest that this native plant species may play a role as engineer species with positive implications for the phytostabilization of Mediterranean PTE contaminated soils and their ecological restoration.
... Proper selection of plant species and soil amendments are relevant aspects determining the success of aided phytostabilization and its associated costs. Currently, the use of native species that are suited to local conditions and have rapid growth cycles (Heckenroth et al. 2016;Mendez and Maier 2008) has been preferred. In terms of soil amendments, they are of great importance for improving several conditions of mine tailings that limit plant growth (i.e., structure, water-holding capacity, soil nutrient content, organic matter levels, pH, metal(oid) bioavailability, and cation exchange capacity (Mendez and Maier 2008;Clemente et al. 2012;Gil-Loaiza et al. 2016;Cui et al. 2020) and for inoculating the heterotrophic microbiota needed for soil nutrient cycling (Clemente et al. 2012). ...
... Species with similar life traits, like Muehlenbeckia hastulata, seems to have vegetative expansion through compound layering on abandoned tailings located in the semiarid ecosystem of northern Chile, but this has not been quantified or studied (de la Fuente et al. 2011). Under these extremely stressful conditions, it is especially important to select species with tolerance to limiting conditions and that also have vegetative reproduction capabilities to improve the establishment success on tailings and accelerate the recovery of plant cover (Heckenroth et al. 2016). ...
Article
Interest in Baccharis linearis has increased as an alternative for assisted phytostabilization due to its spontaneous colonization of tailings dumps. The search for a novel fast-vegetative propagation technique to accelerate its coverage on mine tailings is a promising research area for sustainable mine closure plans. In this study, we determined the optimal proportion of compost and tailings as growing media to promote fast B. linearis propagation through a compound layering technique. The assessed growing substrates were: 100% tailings, 70% tailings + 30% compost, and 50% tailings + 50% compost. After 84 days of growth, the change in number and height of layering branches, root and shoot dry mass, percentage of ground coverage, and substrate chemical properties were assessed. The main results showed that compound layering of B. linearis is possible with compost addition. The growth of new roots and layering branches was significantly improved by either 30% or 50% compost addition into tailings, due to chemical improvements of substrate (higher nutrients and pH and decreased copper bioavailability). The study confirms that the compound layering of B. linearis may be an effective and novel technique for speeding the reclamation of post-operative mine tailings, which is improved by the incorporation of compost.
... The use of plants to manage mining waste has received high interest from the scientific community worldwide [59,77,187] . Phytoremediation is an effective phytotechnology associated with the soil microbes that can reduce or remove toxic contaminants (organic and inorganic) from the environment [70,77,173] . ...
... The use of plants to manage mining waste has received high interest from the scientific community worldwide [59,77,187] . Phytoremediation is an effective phytotechnology associated with the soil microbes that can reduce or remove toxic contaminants (organic and inorganic) from the environment [70,77,173] . It entails numerous techniques, including; phytostabilization, rhizofiltration, phytoextraction, phytoaccmultation and phytovolatilization [84,100] ( Fig. 1 ). ...
Article
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Mine wastes can result in severe pollution and have unaesthetic impacts on the local environment and negative repercussions on human health. Currently, phytomanagement plans provide a cost-effective and sustainable solution for stabilizing these wastes. This approach remains challenging due to uncertainties about plant species selection, their management, the inimical characteristics of metalliferous, low nutrient status, and poor soil physical structure. Therefore, we are proposing guidelines for the phytomanagement of mine wastes. It is a new concept, still very rarely used especially in Morocco. This review is divided into two mains sections: the first section is a non-exhaustive literature review of the available stabilization methods. The second is a detailed methodology in order to successfully implement a phytomanagement plan for mining waste storage facilities. The methodology entails performing an overall screening of the local flora, followed by an appropriate flora selection according to botanical criteria. The second selection is done according to the availability of the genetic material (seeds) in the field and their germination performance. Field trials are crucial to finalize the promising plant list. Eventually, the valorization of produced biomass should be identified according to the concentration of heavy metals in different parts of the selected plants. The performance criteria of these plants were determined, so that corrective action may be taken if necessary. Through this review, we conducted a detailed analysis of this approach and demonstrated its usefulness and benefits over the long term. We showed that the floristic study is a crucial step to select suitable plants for the phytomanagement plan of the mining wastes. Importantly, this review provide evidence that the phytomanagement process is a cost-effective and sustainable solution for stabilizing mining wastes.
... Moreover, two alien plant species (Chromolaena odorata and Bidens pilosa) are also recognized as hyperaccumulators for the phytoremediation of hazardous heavy metal i.e., cadmium. Therefore, there should be a thorough and integrated selection of plants suitable for phytoremediation that should stabilize the use of local seedbanks and native plant communities with phytoremediation goals [157]. ...
... Native plants demand less attention, are generally well-acclimatized, and, of course, do not present legal problems concerning their seed availability and transport. Mostly due to these reasons, scientists have increased their preliminary assessment of using native plant collection for phytostabilization in protected areas [157]. The possibility of preparing improvised blends of vegetation with phytoremediation properties creates a potential opening in the commercial market. ...
Article
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The use of contaminated soils in food production imposes the need for the reduction in heavy metals concentrations, using various techniques, in order to eliminate the toxic effects of pollution and ensure safety in the consumption of agricultural products. Phytoremediation is a promising, effective, and publicly acceptable method to remove soils’ toxicity. This study aims to investigate the current knowledge on plants’ metal tolerance mechanisms, the use of Mediterranean plants in phytoremediation, and the economic perspective for its application on large scales. A total of 166 research studies were systematically reviewed, based on the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. The findings indicate that phytoremediation has more advantages compared to other techniques. It can be a sustainable and affordable option, especially for developing countries, due to the relatively low application and maintenance costs. Many hyperaccumulating plants have been identified that can be used in soil cleansing, enhancing the applicability and replicability of the method. The selection of the appropriate plant species is based on their specific physiological characteristics to remove undesirable elements from the soils and, in certain cases, there is a preference for use of non-native species. However, such species may exhibit invasive behaviors, introducing high uncertainties and risks in the preservation of local ecosystems, especially in the Mediterranean zone, since they can have a serious impact on the environmental and ecological dynamics of the local plant communities. The use of native plants is generally more advantageous since they are better acclimated, have no effects on the local ecological balance, and can eliminate the legal restrictions for their use (seed availability, planting, etc.).
... These features enable the calamine ecotype of D. carthusianorum to grow and bloom in the presence of elevated levels of heavy metals, making it a potential candidate for revegetation and phytostabilisation of metalliferous mine wastes. Nevertheless, approaches based on native metal-tolerant Caryophyllaceae representatives during remediation of hazardous wastes are still sparse (Ciarkowska & Hanus-Fajerska 2008;Colzi et al. 2011;Muszy nska et al. 2013;Heckenroth et al. 2016;Ciarkowska et al. 2017). Building on our previous data, we developed a propagation protocol for D. carthusianorum, and successfully established shoot cultures of the calamine ecotype . ...
... Until now, better growth and development of ecotypes adapted to metalliferous habitats in comparison to plants of the same species from unpolluted areas during exposure to the same metal level have been well documented for many plants, e.g. Armeria maritima (Olko et al. 2008), Biscutella laevigata (Heckenroth et al. 2016) and D. carthusianorum (W ojcik & Tukiendorf 2014;W ojcik et al. 2015). Nevertheless, the mechanisms underlying the enhanced tolerance to heavy metals are diverse and still not fully understand. ...
Article
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The approach based on metallophytes during reclamation of grounds contaminated with heavy metals is still sparse. Thus, we investigated the response of D. carthusianorum calamine ecotype to Pb and Cd stress. We focused on in vitro selection of tolerant plant material appropriated to direct use on chemically degraded areas. Shoot cultures were treated with various concentration of Pb or Cd ions. Plantlets status was estimated on the basis of micropropagation efficiency, growth tolerance index (GTI) and physiological analysis. Moreover, determination of Pb, Cd and chosen elements content was performed. The application of Pb(NO3)2resulted in stronger growth inhibition than the application of CdCl2. In the presence of Pb ions, the reduction of micropropagation coefficient to 1.1 - 1.8 and the decrease of GTI to 48% were ascertained. On the contrary, Cd ions influenced positively on tested cultures what was expressed by the increase of GTI up to 243% on medium enriched with 1.0 μM CdCl2. Moreover, the photosynthetic pigments content in shoots cultivated on media with CdCl2reached higher values than in control treatment. The adaptation to Cd was associated with decreased accumulation of phenols which amounts changed in the following order: 0.0 μM > 1.0 μM > 3.0 μM > 5.5 μM CdCl2. It seems that high tolerance to Cd is related to potassium uptake which is involved in antioxidant defense. This work presents an innovative approach to the impact of Cd ions on plant growth and suggests a potential biological role of this metal in specimens from metalliferous areas. This article is protected by copyright. All rights reserved.
... Furthermore, the introduced plants might be replaced by local plant species in the contaminated sites once human involvement was withdrawn. For these reasons, screening locally tolerant plant species or utilization the dominant plant species for phytoremediation have become an alternative approach for soil restoration (Zhan et al., 2014;Heckenroth et al., 2016;Zhu et al., 2018). Accordingly, a detailed botany investigation surrounding the contaminated areas is generally required as a prerequisite for a sound phytoremediation practice (Heckenroth et al., 2016;Sun et al., 2016). ...
... For these reasons, screening locally tolerant plant species or utilization the dominant plant species for phytoremediation have become an alternative approach for soil restoration (Zhan et al., 2014;Heckenroth et al., 2016;Zhu et al., 2018). Accordingly, a detailed botany investigation surrounding the contaminated areas is generally required as a prerequisite for a sound phytoremediation practice (Heckenroth et al., 2016;Sun et al., 2016). ...
... In previous studies, many herbaceous (Mahdavian et al. 2017;Heckenroth et al. 2016) and woody plants (Luo et al. 2019;Siebielec et al. 2018), such as Paspalum densum, Setaria parviflora (Rios et al. 2017;Araújo et al. 2015), and Robinia Pseudoacacia (Deng et al. 2020a, b), have proven to be potential candidates for revegetating iron ore-mined areas. In addition, the integration of soil biological indicators with chemical and physical indicators is an important factor in the evaluation of soil quality and the recovery process . ...
Article
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Vegetation restoration is an effective method to improve the ecological environment of mine tailings, which has a profound impact on the potential ecological functions of soil fungal communities; yet, little is known about its beneficial effect on soil ectomycorrhizal fungal community. In this study, the responses of soil characteristics and soil ectomycorrhizal fungal community diversity and structure to different revegetation, as well as the contribution of soil factors to soil ectomycorrhizal community were investigated in Liaoning Province, China. As we anticipated, the presence of vegetation significantly improved most soil properties we studied. What’s more, compared to Korean pine ( Pinus koraiensis Sieb. et Zucc.), Chinese poplar ( Populus simonii Carr), and black locust ( Robinia pseudoacacia L) could better improve soil total carbon, total nitrogen, total phosphorus, and available phosphorus. In addition, soil ectomycorrhizal fungal community diversity in black locust was greater than Korean pine and Populus simonii . Nonmetric multidimensional scaling analyses indicated that soil ectomycorrhizal community significantly differed depending on different revegetation types. Thus, these results indicated that black locust could be a suitable species for the revegetation of iron mine tailings. The study provided theoretical basis for ecological restoration of iron mine tailings using local plant species.
... The diversity of plant species found at a site can be strongly influenced by concentrations of inorganic and organic contaminants [41][42][43]. Due to the high concentrations of petroleum hydrocarbon contamination (Supplementary Table S1) that greatly affected the diversity and distribution of spontaneous plant species [31], few plant species co-occurred in all three decantation basins targeted in our study, among which were the two selected species P. tremuloides and E. elliptica. The soil contamination could also significantly reduce the number of species or modify the respective abundance of AMF species in a community [24,39]. ...
Article
Arbuscular mycorrhizal fungi (AMF) have been shown to play an important role in increasing plant fitness in harsh conditions. Therefore, AMF are currently considered to be effective partners in phytoremediation. However, AMF communities in high levels of petroleum pollution are still poorly studied. We investigated the community structures of AMF in roots and rhizospheric soils of two plant species, Eleocharis elliptica and Populus tremuloides, growing spontaneously in high petroleum-contaminated sedimentation basins of a former petrochemical plant (91,000 μg/Kg of C10–C50 was recorded in a basin which is 26-fold higher than the threshold of polluted soil in Quebec, Canada). We used a PCR cloning, and sequencing approach, targeting the 18S rRNA gene to identify AMF taxa. The high concentration of petroleum-contamination largely influenced the AMF diversity, which resulted in less than five AMF operational taxonomical units (OTUs) per individual plant at all sites. The OTUs detected belong mainly to the Glomerales, with some from the Diversisporales and Paraglomerales, which were previously reported in high concentrations of metal contamination. Interestingly, we found a strong phylogenetic signal in OTU associations with host plant species identity, biotopes (roots or soils), and contamination concentrations (lowest, intermediate and highest). The genus Rhizophagus was the most dominant taxon representing 74.4% of all sequences analyzed in this study and showed clear association with the highest contamination level. The clear association of Rhizophagus with high contamination levels suggests the importance of the genus for the use of AMF in bioremediation, as well as for the survey of key AMF genes related to petroleum hydrocarbon resistance. By favoring plant fitness and mediating its soil microbial interactions, Rhizophagus spp. could enhance petroleum hydrocarbon pollutant degradation by both plants and their microbiota in contaminated sites.
... This activity generated massive Pb and Zn-rich slags (Gelly et al., 2019;Testiati et al., 2013) and atmospheric emissions of highly metalconcentrated particles, specifically with Pb, As and Sb Testiati et al., 2013). Previous studies highlighted the metal and metalloid contaminations of the smelter surroundings, in particular by Pb, As, Sb and Zn ( Heckenroth et al., 2016;Affholder et al., 2013;Testiati et al., 2013;Gelly et al., 2019). ...
Article
This study highlights the trace metal and metalloid (TMM) accumulation in Rosmarinus officinalis L. and its chemical responses when exposed to high levels of contamination. R. officinalis individuals growing along a gradient of mixed TMM soil pollution, resulting from past industrial activities, were analysed. Several plant secondary metabolites, known to be involved in plant tolerance to TMM or as a plant health indicator, were investigated. The levels of thiol compounds and phytochelatin precursors (cysteine and glutathione) in the shoots were measured in the laboratory, while a portable non-destructive instrument was used to determine the level of phenolic compounds and chlorophylls directly on site. The level of Pb, As, Sb and Zn contaminations within the soil and plants was also determined. The results highlighted a decrease of TMM translocation with increases of soil contamination. The concentration of TMM in the shoots followed the Mitscherlich equation and reached a plateau at 0.41, 7.9, 0.37, 51.3 mg kg-1 for As, Pb, Sb and Zn, respectively. In the shoots, the levels of thiols and phenols were correlated to concentrations of TMM. Glutathione seems to be the main thiol compounds involved in the tolerance to As, Pb and Sb. Phenols indices, using non-destructive measurements, may be considered as an easy way to establish a proxy to estimate the TMM contamination level of the R. officinalis shoots. The study highlights metabolic processes that contribute to the high potential of R. officinalis for phytostabilisation of TMM in contaminated areas in the Mediterranean.
... The use of native plants for phytoremediation and restoration of Mediterranean metalenriched areas has been reported due to their metal-tolerance and adaptation to local conditions(Boukhris et al., 2015;Mendez and Maier, 2008;Parraga-Aguado et al., 2014;Baker et al., 2010;Marchiol et al., 2013).Heckenroth et al. (2016) reported that some native plant species including Coronilla juncea and Globularia alypum for shrubs, and Biscutella leavigata, Lobularia maritima, Piptatherum caerulescens, Silene vulgaris for perennial grass and forbs, showed significant positive correlations with the metals and metalloids contamination level that suggested their highe ...
Chapter
The unprecedented growth in industrialization has significantly increased pollution in the environment causing public health concerns. The remediation of various contaminated environmental matrices presents a global challenge. Phytoremediation using native plants can serve a dual purpose of site remediation and ecological restoration. Native plants provide an ideal residence for microbial community in their rhizosphere with enzymatic ability to accumulate, stabilize, biodegrade or volatilize various inorganic and organic contaminants. A case study that compared a native plant, Chromolaena odorata, from crude oil-polluted land in Nigeria against a referenced plant, Medicago sativa, for polycyclic aromatic hydrocarbons (PAHs) remediation is presented in this chapter. It was observed that the native plant thrived, tolerated and degraded PAHs better than the reference plant but with no significant difference in PAH degradation. The use of plants is well suited to its natural contaminated area and solar-driven, prevents erosion and eliminates secondary airborne and waterborne waste but with some challenges. Phytoremediation using native species may be effective and efficient than its non-native counterparts, and it is ecologically safer, cheaper, aesthetically pleasing, socially acceptable and easier to cultivate. Native plants in phytoremediation can be further enhanced and improved using molecular techniques to optimize the harvest time, reduce growth duration and increase biomass production and root depth.
... which may rapidly remediate soils, but irreversibly damage the ecological environment (Cameselle et al. 2013;Heckenroth et al. 2016;Luo et al. 2017a,c). ...
Chapter
Environmental pollution by metal(loid)s (e.g., heavy metals—HMs) is a severe problem worldwide, as soils and aquatic resources became increasingly contaminated, threatening land ecosystems, surface and groundwater, as well as food safety and human health. The primary sources contributing to this extended pollution are anthropogenic inputs related to the burning of fossil fuels, mining and continued industrial activities, disposal of municipal solid wastes and wastewater discharges or use for irrigation, and excessive utilization of fertilizers and pesticides. A consequence of these anthropogenic activities is an increase of contaminated areas, which should be remediated to prevent or mitigate transfer of contaminants into terrestrial, atmospheric, or aquatic environments. Point and diffuse contamination by organic and inorganic pollutants causes wide concerns, and intentional or accidental introduction of these substances in the environment may represent serious impacts on public health.
... Lange et al. [24]reviewed the various Cu tolerant species found globally and reported that plants can grow up to 100 mM (Haumaniastrum robertii) in nutrient solution and up to 9000 mgg À1 (Aeollanthus subacaulis) in soil medium. However, with time it was realized that high biomass producing, locally suitable native plants having short generation time can be a better option for phytoremediation of a contaminated site as compared to exotic hyperaccumulators [25]. The search for locally adapted potential accumulator plants began and led to identification of Cu accumulator like Eclipta alba [26]. ...
Article
Sesuvium portulacastrum (L.) is a halophytic phytoremediator plant with potential for significant accumulation of metals and metalloids. The present work evaluatedthe physiological and biochemical responses of Sesuvium plants to copper (Cu) exposure (100–500 μM) for 30 d in field conditions. Plants demonstrated significant copper accumulation that increased with the increase in Cu concentration of the medium (maximum 254 µg g⁻¹ DW at 500 µM). The root dry weight was not significantly affected at 500 μM while shoot dry weight decreased significantly. Total soluble proteins, photosynthetic pigmentsand malondialdehye (MDA) were declined significantly beyond 100 μM after 30 d. Among metabolites and enzymes of thiol metabolism, total non-protein thiols (NP-SH), γ-glutamylcysteine synthetase and glutathione reductase did not show significant effect while cysteine, serine acetyltransferase, and cysteine synthaseshowed a significant decline beyond 100 μM. The level of proline, glycine betaine and total phenolics also showed decreasing trend with the increase in Cu concentration. In conclusion, plantsare potential phytoextractor of Cu but do suffer from the toxic effects of Cu at high concentration of 500 μM. Sesuvium plants therefore appear suitable for use in phytoremediation purpose at low Cu concentrations (100 – 250 μM).
... Heckenroth et al. [141] presented a GIS-based analysis, which, combined with multivariate analyses to identify the hyperaccumulator species, demonstrated the variation in phytoremediation effects of native plant species. Chaudhary et al., [139] coupled GIS with PCA to map out microbial-assisted phytoremediation. ...
Chapter
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Soil is a dynamic system that serves a wide range of functions supporting human activities and ecosystems. The extent of heavy metal soil contamination worldwide is evident. Phytoremediation is a strategy that takes advantage of natural metabolic and transport processes of plants for soil remediation. As a green alternative to traditional remediation technologies, phytoremediation offers particular advantages when applied to contaminated soils spanning large areas. A phytoremediation value chain concept is presented in this chapter, where six echelons across the value chains have been be identified; phytoremediation and metal removal, biomass cultivation and supply, refinery for bioproducts, storage, distribution, and demand. Despite empirical effort to combine phytoremediation with the biorefinery concept and cropping system planning for hyperaccumulator species and metal removal, the value chain of phytoremediation remains an open challenge. Notably, phytoremediation value chains are complicated by their interconnection with soil metal contamination and other environmental variables as well as multi-echelon complexity. This chapter discusses phytoremediation value chain characteristics and design challenges, covering an overview of phytoremediation processes and mechanisms, and empirical research in soil metal remediation by terrestrial plant species. A critical review of the state-of-the-art modelling highlights emerging research gaps and identified future research frontiers to unlock the complexity of phytoremediation value chains. This chapter is concluded with a proposed phytoremediation systems modelling framework which is underpinned by process systems engineering approaches to inform the multi-criteria multi-echelon decision-making on phytoremediation-biorefinery value chains.
... Moreover, there are many advantages to using native plants in phytoremediation since they are better adapted to the soil and climate conditions, leading to a better survival, growth, and reproduction of native plants under environmental stress. Furthermore, native plants do not disturb the ecosystem (Yoon et al. 2006;Heckenroth et al. 2016;Aihemaiti et al. 2018). ...
Article
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Several human activities such as mining, smelting, or transportations lead to trace metal pollution in soil. The presence of these pollutants can represent environmental and organism health risks. Phytoextraction can be used to remediate trace metal–contaminated soils. It uses the plants’ ability to remove trace metals from soil and to accumulate them in their shoots, which can then be harvested. We studied the spontaneous vegetation growing on a brownfield located in France. The use of native plants is interesting since spontaneous vegetation is already well adapted to the site’s environmental conditions leading to a better survival and growth than non-native plants. Ten native plant species were sampled, and the Cr, Cu, Cd, Ni, Pb, and Zn concentrations present in their shoots were measured. In order to determine the plant’s capacity to extract trace metals from the soil, the bioconcentration factor (BCF) was calculated for each plant and trace metal. Plants with a BCF greater than 1 are able to accumulate trace metals in their shoots and could be a good candidate to be used in phytoextraction. Results underscored one new accumulator plant for Zn, Tussilago farfara L., with a BCF value of 3.069. No hyperaccumulator was found among the other sampled plants. Our preliminary study showed that T. farfara is able to accumulate zinc in its shoots. Moreover, this native plant is a pioneer species able to quickly colonize various habitats by vegetative multiplication. That is why T. farfara L. could be interesting for zinc phytoextraction and could be worth further studies.
... Anthropic soil Cu enrichment, derived from long-term mining operations among other sources, has caused serious consequences to productive lands, natural ecosystems, and human health (Lam et al., 2016;Tordoff et al., 2000;Wang and Liu, 2003). In this context, phytostabilization-the use of metal tolerant plants for in situ immobilization of potential pollutants the at soil level-has been proposed as a cost-effective alternative to control metal dispersion and reduce environmental risks (Ginocchio and Baker, 2004;Heckenroth et al., 2016). However, depending on site-specific conditions (i.e., climate), metal-enriched soils could coexist with other co-occurring stresses, such as drought and salinity, which can further restrict phytostabilization efforts (Ginocchio et al., 2017;. ...
... Steel slag is highly reactive and when exposed to rainwater it is known to release ecotoxic metals into the surrounding water bodies and soils (Meng & Liu, 2000;Oliveira et al., 2017). These biotopes may thus host only a fraction of the potential colonizers (Heckenroth et al., 2016). ...
Article
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A phytosociological investigation of spontaneous vegetation on seven-year-old ferro-manganese and silico-manganese slag heaps in southern Croatia showed a predominance of ruderals and weeds (Chenopodietea, Artemisietea vulgaris) and taxa of dry open habitats (Festuco-Brometea, Sedo-Scleranthetea). The limited number and cover of woody taxa seem to indicate an early successional stage in the process of development of natural vegetation. However, we recommend removing the heaps from the area and initiating soil remediation according to Croatian law, EU standards and obligations.
... In most of the cases, plant selection is assessed for commercial phytoremediation (preferentially phytoextraction but not excluding phytostabilization) and is designed on agronomy principles using crops and amendments [5][6][7] and far less on the basis of ecological concepts such as trait-based selection [8][9][10]. ...
Article
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The selection of plant species at mine sites is mostly based on metal content in plant parts. Recent works have proposed referring to certain ecological aspects. However, plant traits for plant metal-tolerance still need to be accurately assessed in the field. An abandoned Zn-Pb mine site in Gard (France) offered the opportunity to test a set of ecological criteria. The diversity of micro-habitats was first recorded through floristic relevés and selected categorical and measured plant traits were compared for plant species selection. The floristic composition of the study site consisted in 61 plant species from 31 plant families. This approach enabled us to focus on seven wild plant species naturally growing at the mining site. Their ability to form root symbioses was then observed with a view to phytostabilization management. Four species were considered for phytoextraction: Noccaea caerulescens (J. et C. Presl) FK Meyer, Biscutella laevigata L., Armeria arenaria (Pers.) Schult. and Plantago lanceolata L. The metal content of their aerial and root parts was then determined and compared with that of soil samples collected at the same site. This general approach may lead to the development of a knowledge base for assessment of the ecological restoration trajectory of the site and can help in plant selection for remediation of other metal-rich soils in the Mediterranean area based not only on metal removal but on ecological restoration principles.
... These cleanup strategies include: surface capping and encapsulation under context of physical approach; electro-kinetics and vitrification under the context of electrical approach; soil flushing and immobilization under the context of chemical approach; and finally phytoremediation under the context of biological approach, respectively . A common concern about employing chemical and physical methods for cleaning up the contaminated areas is related to suitability due to economic consideration and estimation for being harmful due to chemical reagent utilization causing further contamination in the soil (Heckenroth et al. 2016;Sarwar et al. 2017;Fasani et al. 2018;Sun et al. 2018a). Therefore, phytoremediation as an in situ safe and cost-effective way of cleaning up these organic/inorganic contaminants primarily from soil using plants and some plant-associated microorganisms is the most convenient choice nowadays (Arslan et al. 2017;Feng et al. 2017;Gerhardt et al. 2017). ...
Article
Contamination by heavy metals including As, Cd, Co, Cu, Fe, Hg, Mn, Ni and Zn in agricultural fields is a global safety issue. Indeed, excessive accumulations of metals have detrimental effects on life by altering cell components such as lipids, proteins, enzymes and DNA. Phytoremediation appears as a solution to remove metals from contaminated sites, yet metal uptake is usually low in most common plants. Therefore, genetically engineered plants have been designed for higher efficiency of metal accumulation. Here, we review metal phytoremediation by genetically engineered plants with focus on metal uptake and transport, mechanisms involving phytochelatin and metallothionein proteins, toxicity, plant species, methods of gene transfer and gene editing.
... Major contaminants such as lead, copper, zinc and arsenic (Pb, Cu, Zn and As, respectively) were detected at high levels in the soils ( Testiati et al., 2013;Affholder et al., 2013;Affholder et al., 2014), and in particular in the soils of the A. tragacantha habitat ( Laffont-Schwob et al., 2011). Therefore A. tragacantha may be considered as a pseudo-metallophyte ( Heckenroth et al., 2016). Literature on the metabolism of A. tragacantha is very scarce, and its potential ability for TMM phytostabilization, i.e. the use of plant cover aiming at reducing the mobility of contaminants of a soil, calls for a better understanding of the underlying mechanisms of this tolerance (Laffont-Schwob et al., 2011). ...
Article
Astragalus tragacantha is a protected plant species in France that grows even in the trace metal and metalloid (TMM) polluted soils of the Calanques National Park (PNCal). Soils are mainly contaminated by lead, copper, zinc and arsenic. An ex situ experiment was conducted, firstly to determine the molecular responses and root traits involved in the TMM tolerance of this plant species by growing individuals in a soil from the surroundings of one of the brownfields of the PNCal, known as l'Escalette, where this plant species grows spontaneously. Secondly, in order to determine the plasticity of these responses, seeds were collected from three different populations, 1 at l'Escalette (polluted site), one from the Frioul archipelago (non-polluted, insular site) and one from La Seyne (non-polluted, littoral site). The results of this study confirmed the capacity of A. tragacantha to germinate and grow in TMM contaminated soils. Only moderate significant variations in chlorophyll and flavonol indices, proline content and antioxidant activities were detected between polluted and control soil conditions for all populations. The main driver for A. tragacantha TMM tolerance seemed to be its ability to be associated with root symbionts i.e. arbuscular mycorrhizal fungi and dark septate endophytes, corresponding to a nutrient-uptake strategy trait. This work provides support for the challenge of A. tragacantha conservation along the littoral of the PNCal, because increasing the number of A. tragacantha individuals would both increase vegetation cover of the polluted soils to reduce the pollution transfer and reinforce the populations of this species.
... To overcome these physico-chemical limitations, organic/inorganic amendments are often added to assist in the establishment of a vegetation cover for the in situ phytostabilization of mine tailings (Alvarenga et al. 2009;Gil-Loaiza et al. 2016;Pardo et al. 2017;Acosta et al. 2018). Numerous studies of species that can potentially be used for the phytoremediation of heavy metal-contaminated soils in mining regions have mainly focused on spontaneously colonizing herbaceous plants in mining regions (Conesa et al. 2007;Heckenroth et al. 2016;Fernandez et al. 2017;Mahdavian et al. 2017) and have aided phytostabilization with the addition of amendments (Lee et al. 2014;Gil-Loaiza et al. 2016;Yang et al. 2016b;Touceda-González et al. 2017), whereas fewer attempts have been made to evaluate the efficiency of woody plant species restoration under field conditions (Dominguez et al. 2008;Parra et al. 2016;Touceda-González et al. 2017). Woody plants are more suitable for the phytostabilization of several metal(loid)s than herbaceous species because woody plant species have large plant biomasses and tolerate heavy metals (Mendez and Maier 2008;Dimitriou et al. 2012;Párraga-Aguado et al. 2013). ...
Article
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Purpose Zinc smelting activity generates large volumes of highly toxic waste slags and poses a potential extreme environmental risk for the surrounding areas. The establishment of a vegetation cap for the phytostabilization of abandoned mine tailing heaps using plants is usually considered a beneficial approach. This study aimed to evaluate the suitability of phytostabilization of zinc smelting slag using four woody plants combined with organic amendments, to investigate the distribution of heavy metals in the slag–plant system, and to better understand how the direct revegetation of a zinc smelting slag site can influence the mobility and geochemical fraction of heavy metals. Materials and methods Slags were collected from the areas planted with vegetation (Arundo donax, Broussonetia papyrifera, Robinia pseudoacacia, and Cryptomeria fortunei) and a bare area in a zinc smelting waste slag site using an indigenous method. Physicochemical properties were determined with the usual procedures. The geochemical fraction and bioavailability of heavy metals was determined using the three-step modified European Community Bureau of Reference (BCR) sequential extraction and diethylene triamine pentaacetic acid (DTPA) sequential extraction schemes. Heavy metal concentrations (Cu, Pb, Zn, and Cd) in the slag and plant samples were also measured. Results and discussion Vegetation planted directly in the zinc smelting waste slag significantly enhanced the nutrient accumulation and reduced the bioavailability of heavy metals (Cu, Zn, and Cd) with the exception of A. donax for Zn and Cd. The presence of four woody plants increased the bioavailability of Pb. Sequential extraction revealed that revegetation reduced the acid-soluble extractable fraction and increased the fraction of heavy metals associated with the Fe/Mn oxy(hydr)oxides or organic matter. This is attributed to the establishment of plant-enhanced weathering of minerals in the waste slag that resulted in the formation of an amount of dissolved metals, and the amount of dissolved metals was partly redistributed into the soluble extractable fraction of the zinc smelting waste slag. The final concentration of metals (Cu, Pb, Zn, and Cd) in the soluble extractable fraction is dependent on the dynamics of metals induced by root activity in the rhizosphere. Much lower levels of heavy metals with lower translocation factors accumulated in the four woody plants than in the associated slags. Conclusions We conclude that the studied four woody plants showed a beneficial vegetation cover and phytostabilization potential within 5 years of revegetation. These woody plants have the potential for high heavy metal tolerance and low heavy metal accumulation. Therefore, these woody plants could be used for revegetation and phytostabilization of zinc smelting slag sites under field conditions.
... Исследованы устойчивость и продуктивность тех или иных видов древесных растений, влияние физико-химических свойств грунтов на успешность облесения территорий, эффективность содействия человека зарастанию лесом промышленных отвалов, выполнение древесными растениями функций аккумулирования химических токсикантов (выполнения роли фитофильтров) [Кулагин, Тагирова, 2016]. Вторая «волна» аналогичных работ интенсифицировалась уже в зарубежных странах в связи с популяризацией идей фиторемедиации загрязненных земель растениями [Bolan, Park, Robinson, 2011;Capuana, 2011;Heckenroth, Rabier, Dutoit, 2016], в том числе древесными [Pulford, Watson C, 2003]. ...
Article
Wood density analysis of 16 model trees in four habitats of Scots pine (Pinus sylvestris L.) was carried out on the territory of the Uchalinsky mining and processing plant (the Southern Urals), contaminated with heavy metals. A negative correlation (r = - 0.947) was found between this indicator (it varies from 406±1.0 to 520±2.0 kg/m3 in individual biotopes) and the average annual growth in height (it varies from 34.2 ±1.2 to 62.4 ± 3.2 cm). Density of the wood is formed on the dumps of the plant with less access to nutrients, compared to areas with formed soil. The obtained data prove the relatively high potential of Scots pine for natural phytoremediation of technogenic lands of mining enterprises that pollute the environment with heavy metals.
... Uptake of metal ions among plants may differ with metal speciation, type (monocot or dicot), seasonal variations and level of contamination in the locality, presence of root iron plaques, soil properties, tidal inundations, rainfall and salinity (Rozema et al., 1990;Rai et al., 1995;Otte et al., 1993;Caçador et al., 2000). Halophytes with phytoremediation potential may be used as non-destructive tool for cleaning heavy metals from contaminated soils (Heckenroth et al., 2016). ...
Article
Coastal wetlands primarily serve as natural sinks of trace metals and their importance for phytoremediation is well known at global level. There are some reports on trace metal availability in soil sediments of the Karachi coast but studies on accumulation and translocation to harvestable (Shoot) parts among halophytes of the littoral zones have not been conducted. Hence, phytoremediation potential of six naturally existing halophytes (Aeluropus lagopoides, Arthrocnemum macrostachyum, Atriplex stocksii, Avicennia marina, Cressa cretica and Suaeda fruticosa) was assessed for cleaning metal (Mn, Zn, Pb and Cr) polluted soils of the Karachi coast. Seasonal (winters, pre and post-monsoon summers) and spatial (three littoral zones: viz., site – I: Sandspit, site – II: Do-Dariya/ Clifton and site – III: Korangi creek) variations in soil and plant metals of the Karachi coast were studied. Soil Zn, Pb and Cr were generally higher in winters, Mn and organic matter in summers (7 – 11%) while pH values ranged between 7.15 – 7.5 in all seasons at site – III. All tested species had potential for cleaning Pb through their harvestable part (shoots) with A. stocksii as prominent candidate (16 mg Kg⁻¹) at site – I. Cressa cretica emerged as exclusive candidate for Zn phytoremediation (96 mg kg⁻¹) at site – I, while S. fruticosa, A. macrostachyum and A. lagopoides showed bioaccumulation in pre-monsoon summers at site II. Aeluropus lagopoides with higher Mn in post monsoon summers (62 at site – III and 53 mg kg⁻¹ at site – II) and Cr (7.1 mg kg⁻¹ at site – II and 14 mg kg⁻¹ at site – III) appeared exclusive bioindicator with potential of for cleaning all metals (Mn, Zn, Pb and Cr) at different sites. Metal bioaccumulation at study sites appeared species specific and varied seasonally among tested halophytes.
... Moreover, there are many advantages to using native plants in phytoremediation since they are better adapted to the soil and climate conditions, leading to a better survival, growth and reproduction of native plants under environmental stress. Furthermore, native plants do not disturb the ecosystem (Yoon et al. 2006;Heckenroth et al. 2016;Aihemaiti et al. 2018). ...
Thesis
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Chaque année, 50 millions de mètres cubes de sédiments sont excavés en France. Parmi eux, certains sont contaminés et des solutions doivent être trouvées pour les valoriser. Dans cette étude, des sédiments excavés ont été mélangés avec le sol du site d’accueil, tous deux contaminés en ETM et HAP, afin de créer un technosol à traiter en phytoremédiation par Miscanthus x giganteus (MxG). L’objectif de ce travail consistait à améliorer la rhizodégradation des HAP et la phytostabilisation des ETM tout en augmentant la productivité de MxG en vue de la valorisation de sa biomasse. Pour cela, deux expérimentations ont été réalisées. La première associait MxG en co-culture avec le trèfle blanc et la seconde couplait MxG en monoculture et en co-culture avec la bioaugmentation par des microorganismes hydrocarbonoclastes endémiques du technosol. D’après les résultats obtenus, la co-culture apparaît comme la technique la plus intéressante pour améliorer la phytoremédiation des HAP et des ETM et pour améliorer la qualité du technosol comparé à la phytoremédiation assistée par bioaugmentation. De plus, la plantation de trèfle blanc pour réaliser la co-culture est plus économique, plus rapide et plus simple à mettre en œuvre que la bioaugmentation. Ces résultats devront être confirmés in situ et d’autres espèces végétales pourraient également être testées en association avec MxG afin de coupler la rhizodégradation des HAP avec la phytoextraction des ETM.
... Relative to conventional treatments which can rapidly remediate soils but irreversibly damage the ecological system and the agricultural function of substrates (Cameselle et al., 2013;Heckenroth et al., 2016), including incineration, landfill, chemical washing, physical covering, solidification and vitrification, phytoremediation is a solar driven and environmentally friendly technique because it decontaminates contaminants along with the metabolism processes of species without disturbing the physical, chemical and ecological characteristics of soils (Mojiri et al., 2016;Salam et al., 2017). Low survival and biomass production of plants grown on contaminated soils and long time required for species to remove exceeding contaminants from substrates were the two major factors restricting the success of phytoremediation (Luo et al., 2016;Niazi et al., 2012). ...
Article
Multiple techniques for soil decontamination were combined to enhance the phytoremediation efficiency of Eucalyptus globulese and alleviate the corresponding environmental risks. The approach constituted of chelating agent using, electrokinetic remediation, plant hormone foliar application and phytoremediation was designed to remediate multi-metal contaminated soils from a notorious e-waste recycling town. The decontamination ability of E. globulese increased from 1.35, 58.47 and 119.18 mg per plant for Cd, Pb and Cu in planting controls to 7.57, 198.68 and 174.34 mg per plant in individual EDTA treatments, respectively, but simultaneously, 0.9-11.5 times more metals leached from chelator treatments relative to controls. Low (2 V) and moderate (4 V) voltage electric fields provoked the growth of the species while high voltage (10 V) had an opposite effect and metal concentrations of the plants elevated with the increment of voltage. Volumes of the leachate decreased from 1224 to 134 mL with voltage increasing from 0 to 10 V due to electroosmosis and electrolysis. Comparing with individual phytoremediation, foliar cytokinin treatments produced 56% more biomass and intercepted 2.5 times more leachate attributed to the enhanced transpiration rate. The synergistic combination of the individuals resulted in the most biomass production and metal accumulation of the species under the stress condition relative to other methods. Time required for the multi-technique approach to decontaminate Cd, Pb and Cu from soil was 2.1-10.4 times less than individual chelator addition, electric field application or plant hormone utilization. It's especially important that nearly no leachate (60 mL in total) was collected from the multi-technique system. This approach is a suitable method to remediate metal polluted site considering its decontamination efficiency and associated environmental negligible risk.
... Our results can be interpreted in light of changes in weather conditions, which usually vary with absolute latitude. The entire process of succession is continuously restricted by site conditions, even after major interventions (e.g., via soil covering, fertilization, seeding etc. (Courtney et al., 2009, Cseresnyes et al., 2014, Heckenroth et al., 2016, Yu et al., 2010). Such measures can only support succession in the initial stages (Siegel, 2002). ...
Article
Mining is the most destructive human activity towards ecosystems through changing the terrain, substrate properties, and vegetation community structure. Vegetation succession, the theoretical basis of restoration, is influenced by site conditions and anthropogenic intervention. In order to provide general practical applications for mine restoration, it is critical to identify the optimal intervention that promotes succession, and the influence of climates. Here, we hypothesized that high-intervention contributes to positive characteristics and more successful succession, while increasing climatic severity presents negative characteristics and succession is hard to succeed. In this study, we collected 55 global studies (n = 804) on the vegetation succession of abandoned metal mines, and evaluated the ecological characteristics and successional trends under spontaneous succession and anthropogenic intervention conditions by conducting meta-analyses. Furthermore, we considered factors that may affect the vegetation succession after closing mines, including geological conditions, mining area (area of degraded land in mine field) and mining time (duration of mining operations). Species richness and evenness increased with the age of succession under low- and non- intervention conditions, while coverage increased under high-intervention, and species diversity decreased significantly with increasing mining time in cold areas. There were significant differences in succession trends under different climate types. The vegetation structure was more likely to develop towards the target vegetation in megathermal and mesothermal than in microthermal regions. We contend that a low level of intervention can help succession, while high-intervention will not. Vegetation succession can be achieved more easily with less climatic severity, and the reduction of large-scale mining processes (area and time) can increase vegetation evenness, especially for continental or microthermal regions.
... Phyto-technologies in recent years have made giant steps and have clarified and discovered mechanisms for responding to abiotic stresses with particular regard to detoxification strategies from pollutant. In addition, natural capacity of the plants was demonstrated in relation to their fungus, mycorrhiza and bacteria dominated rhizosphere [6][7][8]. ...
Article
The pollution of metals and metalloids in soils caused by industrial activities is a major issue and invests the whole planet earth. The area we investigated is present in the Petrochemical of Porto Torres (Sardinia-Italy), which has an extension of about 1100 ha, is located along the northwest coast of Sardinia, about 1.8 km west of the town and with a surface contamination (0-50 cm depth) from As, Tl and V. The aim of this study is the investigation of spontaneous species present in the areas and the possibility to find some species among those useful to the phytoremediation. We also evaluate (mesocosm) some species that spontaneously live in the Porto Torres area but not on the area under consideration such as Dittrichia viscosa and Piptatherum miliaceum which, according to literature data, showed a good attitude towards phytoremediation. In conclusion, Dittrichia viscosa, Piptatherum miliaceum and Bromus madritensis are good candidates to build a phytoremediation design.
... There are many ancient and abandoned slag heaps of non-ferrous metals from mining in Yunnan province, southwestern China, and successive vegetation covers have been established spontaneously in these slags at different times. These indigenous plants are potential reservoirs of germplasm for phytoremediation purposes [17,18], as these are not only tolerant to the stressed environment but are also adapted to the prevailing local climate conditions. Among these, an herb species native to the Himalayas known as Oxyria sinensis (Polygonaceae) has attracted a lot of attention for potential revegetation, due to its high metal tolerance and the ability to generate considerable biomass, as well as the more easily accessible sexual seeds and asexual rhizomes [19,20]. ...
Article
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Oxyria sinensis adopts a tolerant strategy as a metal excluder to survive toxic metal concentrations. Biodiversity and the endophytic fungal community colonizing the O. sinensis roots were assessed from a mining area (MA) and a neighboring non-mining area (nMA) in southwestern China. All O. sinensis roots formed fully developed dark septate endophytes (DSEs) and arbuscular mycorrhizal fungi (AMF). Total DSE colonization was higher for the MA versus nMA, in contrast to the total AMF colonization in the two sites. The DSE colonization was higher than AMF colonization regardless of the site. Pure-culture data showed that the fungi closely related to Exophiala, Cadophora and Phialophora dominantly colonized the O. sinensis roots. A total of 450 operational taxonomic units (OTUs) were identified showing the presence of a distinct fungal community in MA and nMA, which was shaped by soil physiochemical properties, including soil Zn concentrations and organic matter. We found that O. sinensis accumulates and adapts efficiently to local endophytic fungi to achieve the expansion of its community, including the spontaneously reclaimed DSE. This property may be targeted to achieve its colonization with a pioneer plant for phytoremediation in the restoration of a vegetation cover in a metal-contaminated area.
... In this study, the CCA model was useful for investigating similarities and differences of soil characteristics of every site, Species-environment relationship, and the relationship among the accumulation of metals in roots and shoots of plants, which verifies the application of canonical community ordination's methods for phytoremediation studies. In this regard, using redundancy analysis (RDA), plant species groups were identified along the contamination gradient, thus metal-tolerant (Heckenroth et al., 2016) and hexachlorocyclohexane-tolerant (Balázs et al., 2018) species were proposed for phytoremediation purposes. ...
Article
Phytoremediation is a cost-effective, environmentally-friendly and emerging remediation technology that treats polluted areas using plants, having the potential to restore ecosystems and make compromised areas useable again, therefore returning a resource to community use. In the present work a study was conducted on the contamination of soil by heavy metals (Zn, Pb, Cr, Cd, and Co) in the mining area of Angouran (northwestern Iran) and on their uptake by 25 native species present in the mining district, in order to evaluate their potential use in phytoremediation interventions. Plant and soils from three sites around the mine were sampled and characterized, and metals accumulation and translocation were evaluated. Principal Component Analysis (PCA) and Cluster Analysis (CA) were applied to study the behavior of species in the accumulation and translocation of the elements in their tissues. The contents of Zn, Pb, Cr, Cd, and Co in the studied plants were, respectively, 31.77–723.05, 7.78–233.25, 1.77–21.57, 0.04–7.92, and 0.15–9.97 mg/kg. Among the 25 species, 13 plants showed translocation factor greater than one (TF > 1) for Zn, 14 for Pb, 3 for Cr, 10 for Co, and 6 for Cd. Marrubium cuneatum having an accumulation factor greater than one (AF > 1) for Zn and bioconcentration factor greater than one (BCF >1) for Cd can be considered as an accumulator and stabilizer for Zn and Cd, respectively. Also, the highest value of Pb (233.25 mg/kg) and Cr (21.57 mg/kg) were found in the shoot of this plant. Psathyrostachys fragilis with BCF >1 for Co and maximum Pb accumulation in the root can be used as a stabilizer plant for Pb and Co-contaminated soils. Besides, Stipa arabica and Verbascum speciosum, with TF > 1 and rather high AF, could be considered suitable species for removing Zn and Pb through phytoextraction. This research showed that some native species in the study area have considerable potential for developing phytoremediation strategies.
... The metal and metalloid contamination of PNCal soils has previously been partially studied and the diffuse pollution of these soils has been discussed in separate publications (Affholder et al., 2013;Heckenroth et al., 2016;Rabier et al., 2014;Testiati et al., 2013). However, in this study, soil characterization was completed by fertility parameters for the seashore sites. ...
Article
In polluted protected areas, using phytoremediation raises the question of the choice of the plant species to select. As an example, Atriplex halimus has been identified as a proliferative plant species that needs to be eradicated in the Calanques National Park (PNCal). Since it has been proven that the spontaneous populations of this plant species could phytostabilize shore waste deposits generated by past industrial activities within the PNCal territory, its status seems controversial, presenting a dilemma between biodiversity management of a protected area and ecological solutions for pollution management. To address this issue, we assessed the ability of A. halimus to grow on different soils from this territory, in order to estimate the potential invasiveness of this plant in this territory. Petri dish germinations and pot-growth experiments showed 50% germination of seeds collected on local individuals from the most polluted PNCal soil and 20% growth reduction of seedlings. Soil analysis showed that limitation of growth was caused by high pH value and sparsely available micronutrients as well as metal and metalloid contamination. Our results suggested that local populations of A. halimus may stabilize the highly metal and metalloid polluted salt-affected soils of the PNCal, with low seed germination potential lowering the eventuality of a propagation over the PNCal territory. As a consequence of this study, the administration of the PNCal decided not to remove A. halimus populations along the polluted coastline until another solution to prevent pollution dispersal had been found. This laboratory approach may be extended to other similar situations where plant species may be evaluated not only in term of phytoremediation potential but also in term of biodiversity preservation.
... The phytoremediating species must be highly tolerant of the pollutants [6]. The preference is given to an indigenous and naturalized species of the locality, adapted to local climate conditions [7]. It is also best to select a fast growing and high biomass plant with high capacity for uptake of heavy metals [8]. ...
Article
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The boom of tanneries in north India has converted the river Ganga into a waste dumping stream. The tanneries discharge their heavy metal-rich effluents into the river. Tissues of two-year-old tree saplings of Dalbergia sissoo, soil sediments and river water samples were collected from three sites along the river Ganga at Jajmau, Kanpur. Site-1 was located 1 km upstream from the point of discharge of the effluents of the tanneries, Site-2 was close to the source point, and Site-3 was about 1 km downstream from the source point. Accumulation of Cu, Cr and Ni in leaves, bark, wood growth rings, soil sediments and water samples was estimated using an atomic absorption spectrophotometer. The tissues of the two-year-old wood growth rings of D. sissoo accumulated large amounts of Cr, Cu and Ni. The Cr concentration in leaves, bark and wood rings had a strong, positive and linear correlation (r²) with the Cr concentration in soil sediments. The bio-concentration factors (BCFs) of Cr, Cu and Ni were higher than 1 in the wood, bark and leaves at all three selected sites, indicating the strong phytoremediating ability of the tree. The uptake of Cr and Ni was consistent in the bark and wood growth rings of two successive years. Owing to the strong uptake and accumulating abilities of Cr, Cu and Ni as evident from high BCF values and high biomass, we propose D. sissoo as a suitable species for phytoremediation throughout its range of distribution in Africa, Asia and the Americas.
Article
Metal decontamination and leaching alleviation capacity of Eucalyptus globulus with and without electric field were investigated using ICP-MS. The biomass production of the chosen plant increased from 0.87 kg in planting control without electrokinetic treatment to 1.16 and 1.42 kg in experiments with electric field supplied by storage battery and solar cell, respectively. Under the influence of electric field with a voltage of 6.5 V, significantly more Cd, Pb and Cu were extracted by the species. Precipitation simulation was performed to evaluate the capacity of battery and solar panel to intercept leaching. The total volume of leachate gathered from the control decreased from 1012 mL to 299 and 336 mL in containers treated by storage battery and solar cell, respectively. In addition to reduction of leachate, the leaching mass of Cd, Pb and Cu was decreased significantly by electric fields (both battery and solar cell) treatments. The effect of remediation and environmental risk alleviation by solar cell was comparable with storage battery, at least during the 30-day experimental period. On the basis of the present study, solar cell should be a suitable substitute for conventional power supply to improve metal polluted soil when considering phytoremediation efficiency and energy consumption.
Article
Phytostabilization is a cost-effective long-term bioremediation technique for immobilization of metalliferous mine tailings. However the biogeochemical processes affecting metal(loid) molecular stabilization and mobility in the root zone remain poorly resolved. Roots of Prosopis juliflora grown for up to 36 months in compost-amended pyritic mine tailings from a federal Superfund site were investigated by micro-scale and bulk synchrotron X-ray absorption spectroscopy (XAS) and multiple energy micro X-ray fluorescence (ME-μXRF) imaging to determine iron, arsenic, sulfur speciation, abundance, and spatial distribution. Whereas ferrihydrite-bound As(V) species predominated in the initial bulk mine tailings, rhizosphere speciation of arsenic was distinctly different. Root associated As(V) was immobilized on the root epidermis bound to ferric sulfate precipitates and within root vacuoles as trivalent As(III)-SH3 complexes. Molar Fe:As ratios of root epidermis tissue was 2x times higher than the 15% compost-amended bulk tailings growth medium. Rhizoplane associated ferric sulfate phases that showed a high capacity to scavenge As(V) were dissimilar from the bulk tailings mineralogy as shown by XAS and XRD, indicating a root surface mechanism for their formation or accumulation.
Article
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Soil pollution by trace elements (TEs) from mining and industrial activity is widespread and presents a risk to humans and ecosystems. The use of trees to immobilize TEs (phytostabilization) is a low-cost and effective method of soil remediation. We aimed to determine the chemical composition of leaves and flower buds of Eucalyptus camaldulensis in seven sites along the Guadiamar River valley (SW Spain), an area contaminated by a mine-spill in 1998. E. camaldulensis trees in the spill-affected area and adjacent non affected areas were growing on a variety of soils with pH from 5.6 to 8.1 with low concentration of plant nutrients. The spill affected soils contained up to 1069 mg kg⁻¹ of As and 4086 mg kg⁻¹ of Pb. E. camaldulensis tolerated elevated TE concentrations in soil and, compared to other species growing in the same environment, had low TE concentrations in the aerial portions. Besides tolerance to soil contamination, E. camaldulensis had low bioaccumulation coefficients for soil contaminants. TE concentrations in the aboveground portions were below levels reported to be toxic to plants or ecosystems. Flower buds had even lower TE concentrations than leaves. Despite the relatively low concentration of TEs in leaves they were significantly correlated with the soil extractable (0.01 M CaCl2) Cd, Mn and Zn (but not Cu and Pb). The general features of this tree species: tolerance to impoverished and contaminated soils, fast growth and deep root system, and low transfer of TEs from soil to aboveground organs makes it suitable for phytostabilization of soils contaminated by TEs. In addition, eucalyptus leaves could be used for biomonitoring the soil extractability of Cd, Mn and Zn but not Cu or Pb.
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Phytoremediation is a plant-based and cost-effective technology that could be the possible potential method for providing an alternative to current treatment technologies for wastewater and contaminated ecosystems. It also enjoys popularity with the general public as a green technology. Aquatic macrophytes showed great potential in the field of phytoremediation. They are important tools for heavy metal removal since it basically involves the extraction and translocation of contaminants to aerial parts or inactivation of these toxic metals in a system. In order to exploit its full potential, a comprehensive understanding is needed as to how metal uptake, transport, and trafficking across plant membranes and distribution, tolerance, sensitivity, etc., take place under different environments. Aquatic plants in freshwater, marine and estuarine systems act as receptacle for several metals and have tremendous scope for application in remediation of heavy metals in the environment. Uptake and removal of contaminant varies for each category of aquatic macrophyte, viz. free-floating, submerged and emergent. The mechanisms of metal uptake, role of phytoremediators in metal pollution abatement and progress made in the practical application of phytoremediation of metals by aquatic macrophytes are reviewed in this paper. The paper discusses the phytoremediation potential of most promising aquatic macrophytes for different metals, their practical applications for environmental clean-up and method for safe disposal of phytoextracted biomass.
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In order to investigate the toxicity-resistance of eighteen Chinese native plants in lead (Pb)-zinc (Zn) mine tailings, we categorized their resistance to Pb and Zn, and tested their potential for phytoremediation effectiveness of Pb and Zn. Fourteen woody plant species belonging to 12 families, and 4 herbaceous species belonging to 4 families, were grown in pots with mixtures of 100% tailing +0% peat (CK), 90% tailing +10% peat (A1), and 80% tailing + 20% peat (A2), respectively. Plant height and biomass, chlorophyll content, and Pb and Zn contents of non-rhizosphere spoil mixtures and plant tissues were measured. Fifteen of the plants grew in all three spoil mixtures. Both A1 and A2 had higher plant height and biomass increment and chlorophyll contents than CK. The content of Pb and Zn in plant shoots and roots was CK > A1 > A2. The value of BCF less than 0.1, compared to 1, was a more precise classification basis for plants excluding metals. Screening for Pb and Zn resistant plants and their bioremediation potential produced the following candidate species: Sapium sebiferum, Salix matsudana, Hibiscus cannabinus, Corchorus capsularis, Ricinus communis, and Populus nigra. These species were highly Pb and Zn tolerant species, with notable growth characteristics and capacities to bioaccumulate Pb and Zn from the mine tailings. Compared to CK, the removal of Pb and Zn from non-rhizosphere spoil increased by an average of 9.64% and 9.6%, respectively in A1, but decreased in A2. The results indicated candidate species and 10% peat addition in the tailing were significant in phytoremediation of Pb and Zn regarding environmental safety.
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Functional ecology provides useful tools for selecting native species for rehabilitation purposes. Here, we evaluated a list of native tree and shrub species as candidates for use in waste pile rehabilitation in the Carajás National Forest, eastern Amazon, Brazil, to increase the diversity and stability of the reinstated communities. Native species lists were compiled from vegetation inventories performed in two different ecosystems in the region, i.e., dense evergreen Amazonian forests and ferriferous savannah formations, locally known as cangas. For prospection, we evaluated the functional differences among the forest, canga and waste pile communities and computed the functional space defined by wood density and 14 leaf traits of species that had already established during former rehabilitation efforts targeting the waste piles. Native species falling within this trait space were selected for further initial rehabilitation activities, while species outside this space were considered unsuitable for this purpose. As a proof of concept, we compared the survival of seedlings of selected and nonselected tree species to evaluate their potential for initial rehabilitation activities. We found functional differences in the communities between the rehabilitating waste piles and natural environments but higher functional congruence with forest than with canga ecosystems, making the conversion of waste piles into forests more likely. The assessment of functional differences enabled the identification of additional species for initial waste pile rehabilitation; we present a list of 76 candidates for future waste pile rehabilitation activities in Carajás National Forest. Our approach was validated by the seedling survival experiment, where selected species showed higher survival than nonselected species, highlighting the suitability of the selected species for initial waste pile rehabilitation in the region to increase the species richness and functional redundancy of the reinstated communities. The validation via the seedling survival experiment furthermore encourages the replication of the proposed functional prospection procedure for other environments to be rehabilitated, with different species sets being sought for different regions.
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Recent studies consider the native flora as a potential source of plant candidates for phytostabilization of metal and metalloid (MM) contaminated soils, but ecological restoration is not the main objective of these researches. However, in contaminated areas, phytostabilization should be considered as a useful tool for ecological restoration. The present study takes stock of 3 years of a Mediterranean pilot site implementation using native plant species to recover plant and microbial communities (diversity and functions) together with soil remediation in the Calanques National Park. To determine the success of this operation, three in situ treatments were compared: ecological restoration plots characterized by the handling of physical environment (creation of cultivation terraces) and plants, negative control plots without vegetation but with the same physical environment handling as ecological restoration plots, and positive control plots with natural vegetation and no handling. The results suggest that an ecological restoration trajectory is initiated in the ecological restoration plots, characterized by a partial permanent plant cover. However, there is no evidence of a significant improvement of soil quality (evaluated by soil texture, pH, nutrients and organic carbon contents, cation exchange capacity, microbial biomass and activities) and phytostabilization efficiency after 3 years. Native plant communities and their associated microorganisms may need more time before improving soil quality and MM stabilization under the drastic Mediterranean conditions. Any amendment addition to accelerate restoration and MM immobilization was forbidden in this protected area. Under such conditions, an active restoration need to be carried out in this contaminated area even if resilient dynamics of the native plant communities may sporadically occur over a long period of time.
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The development of the mining industry has led to the appearance in many parts of the world of vast technogenic territories from which toxic heavy metals enter the environment and food chains. Physical, chemical, and biological methods of cleaning industrial land due to technological complexity and high cost are relatively little used on a large scale. Natural forest overgrowth of mining sites and the removal of heavy metals by woody plants can be an effective form of recovery. Therefore, the study of this process is of significant scientific and practical interest. The analysis of the annual growth in height and width of the annual rings of the stem of Scots pine (Pinus sylvestris L.) in 2004–2019 was made on the territory of the Uchalinsky mining and processing plant (South Ural, Russia) contaminated with heavy metals. Relatively high concentrations of copper and zinc were found in soils, roots, bark, young shoots, comparable to exceeding the maximum allowable concentrations. Despite the spatial uniformity of the heavy metal content in the stands, the tree samples significantly differed in terms of annual growth. Results suggest that the lack of nutrients and not stress from exposure to heavy metals is the main reason for relatively low growth rates on slopes of industrial wastes. It was confirmed by studying the annual growth in height of the undergrowth in habitats with different soil cover conservation. The data prove the relatively high potential of Scots pine for the natural recovery of industrial lands polluted with heavy metals by mining enterprises.
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With this study we aimed to assess the effect of the prior development of Piptatherum miliaceum (Pm) in a Technosol on the establishment of Salvia rosmarinus (Sr) as a cash crop. An experimental pot was performed with two biochar (BCh) doses (BCh1 and BCh2) mixed with marble waste and pyritic tailings, with and without Pm. After 12 months of Pm growth, the pots with this species were divided into two sets: Sr alone and Sr + Pm. An agricultural soil (AGR) was used as an external control. The results showed that the growth of Sr led to similar shoot biomass to AGR. Sr + Pm reduced shoot biomass by 50%. Total soil organic and recalcitrant C, and total and recalcitrant N showed the highest values in vegetated pots, with no effect of the BCh rate. The decrease in the soil metals availability was related with increases in soil pH. BCh1Sr + Pm treatment showed a microbial community structure more similar to AGR, related to higher fungal and bacterial abundance, enzyme activities and soluble carbon. Thus, growing Sr + Pm seems a suitable strategy to improve soil properties, including microbial abundance, with low translocation of metals. Although the BCh rate did not affect plant growth or soil physicochemical properties, the lowest rate contributed to the growth of soil microorganisms better. The simultaneous growth of Sr + Pm reduced biomass production, and a source of available nutrients is also recommended. Further studies are needed to test this strategy in the field, and to ensure its suitability and a constant biomass production.
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The management of mine waste has become an urgent issue, especially in semi-arid environments. In this context, and with an aim to inhibit the oxidation of the sulfide tailings of the abandoned mine of Kettara in Morocco, a store-and-release (SR) cover made of phosphate mine waste (PW) was implemented. In order to guarantee its long-term performance, phytostabilization by local wild plant species is currently the most effective and sustainable solution. This study aimed to assess the growth performance and phytostabilization efficiency of five local wild plant species to grow on the SR cover made of PW. A field experiment was conducted for two growing seasons (2018 and 2019), without amendments and with the minimum of human care. PW and the aboveground and belowground parts of the studied plant species were collected and analyzed for As, Cd, Cu, Ni, and Zn. The bioconcentration factor (BCF) and translocation factor (TF) were also calculated. Despite the hostile conditions of the mining environment, the five plant species showed promising growth performances as follows: Atriplex semibaccata > Vicia sativa > Launaea arborescens > Peganum harmala > Asparagus horridus. The five plants showed high accumulation capacity of the trace elements, with the highest concentrations in belowground tissue. Principal component analysis distinguished A. semibaccata as having a high concentration of Cu and As, while Asparagus horridus had higher concentrations of Cd and Zn. In contrast, P. harmala, V. sativa, and L. arborescens demonstrated affinity regarding Ni. According to the BCF (<1) and TF (<1), these plant species could be used as effective phytostabilizers of the studied trace elements. The present study showed that local wild plant species have a great potential for the phytostabilization of PW, and could ensure the long-term efficiency of SR cover.
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The remediation of wood preservative–contaminated sites is an important issue due to the carcinogenic nature of some contaminants derived from wood preservatives (e.g., Cr⁺⁶, arsenate, and pentachlorophenol). This study evaluated the effects of fertilizer application on remediation potential of co-plantings of Salix interior Rowlee. (Salix) and Festuca arundinacea Schreb. (Festuca) in a wood preservative–spiked technosol while considering the potential contaminant and nutrient leaching. Two levels of nitrogen (N) and phosphorus (P) fertilizers, NaNO3 and NaH2PO4 (25 and 75 mg L⁻¹), were applied to achieve three N:P ratios, i.e., 3:1 (75:25), 1:3 (25:75), and 1:1 (25:25), that were compared with a control treatment (0:0 N:P) in a mesocosm experiment. Roots of the plant supplied with 1:1 and 1:3 N:P had more than double arsenic (As) and copper (Cu) amounts (i.e., biomass × concentration) compared to the control ones. Highest As and Cu amounts in shoots were found for Salix stems and Festuca leaves in the 1:3 and 1:1 N:P treatments, respectively. Arsenic and P leaching was high in mesocosms supplied with 1:3 N:P. Contamination and nutrient leaching in the 1:1 N:P treatment did not differ from the control, except for Cu. In conclusion, 1:1 N:P treatment yielded the best results in terms of metal(loid) uptake and contaminant and nutrient leaching. In 1:1 N:P treatment, the maximum values of percent As, Cr, and Cu in Salix and Festuca aboveground were 0.18%, 0.024%, and 1.20% and 0.89%, 0.08%, and 1.78%, respectively.
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Humans have mined a large number of sites for minerals, ores and other natural resources over the past centuries. When looking at a practical benefit of applying quality targets to the brownfield site remediation of an Orphaned Mine, the costs directly correlate with the planned target levels. The main problem seems to be the flue dust and mining waste deposits (Alayet et al. in J Appl Remote Sens 11(1), 2017 [1]), so the research follows the three pillars of sustainable development:
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During the last 30 years, one of the major environmental concerns is related to water pollution. Given the ecological and economic advantages of aquatic plants, the toxic effect of several variety of pollutants to macrophytes entice enhanced attentiveness. An abundant literature shows that most polluting substances which enter in the aquatic environment carry on apparent noxious effects. This chapter is a review of the literature devoted to the chemometric modeling of the toxicity of certain pollutants to aquatic plants.
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Objectives The aim of this study was to assess whether selection breeding in chicory (Cichorium intybus L.) led changes in the susceptibility to Salmonella enterica and Escherichia coli contamination and whether the anatomical traits of the leaves are involved in the possible changes. Materials and Methods Five chicory genotypes subjected to different intensities of selection were compared at the microgreen stage. Bacterial retention was evaluated after leaf incubation for 1.5 h on the surface of the bacterial suspension, followed by rinsing, grinding, plating on selective media, and CFU counting. The density of stomata and trichomes, total stomatal length and width, stomatal pit width, surface roughness and sharpness were evaluated. Results The intensively selected genotype (Witloof) was significantly more prone to contamination ((2.9±0.3) lg CFU/cm 2) as the average of the two bacteril types than the wild accession (Wild) ((2.3±0.4) lg CFU/cm 2) and the moderately selected genotypes (two leaf chicories, Catalogna type, and root chicory ‘Magdeburg’) (on average, (1.9±0.3) lg CFU/cm 2). Witloof microgreens also showed larger stomata (on average + 34% for stoma width and + 44% for pit width), which could justify, at least in part, the higher susceptibility to enterobacteria contamination. In fact, when contamination was performed in the dark (closed stomata), the bacterial retention in Witloof was significantly reduced in comparison with the opened stomata (-44%) and in Wild (-26%). Differences in retention between Witloof and Wild were still observed after UV treatment. The hierarchical clustering performed by grouping the leaf anatomical features was consistent with the chicory genetic groups. Conclusions Our results suggest that the domestication process can affect the safety of produce and that the micromorphological traits of the leaves may be involved.
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Phytoremediation is a cost effective and environmental friendly tool for the remediation of contaminated environment. Certain plant species have the ability to uptake toxic pollutants into their biomass and the rhizosphere microbes can degrade complex pollutants into simpler and less toxic forms. Contamination of soil with petroleum hydrocarbons and associated heavy metals is a major cause of concern in oil producing countries. In our ongoing research, Alfalfa, Indian mustard, Barley and Atriplex plants were screened for remediation of heavy metal contaminated soil and data on heavy metal uptake efficacy is presented. The presentation is focused on the experiments designed to examine the degree of toxicity of oil contaminated soil on alfalfa, Indian mustard, barley and Atriplex species and their ability to uptake heavy metals when administered in a mixture form. Plants were subjected to heavy metal treatment in a growth chamber under controlled conditions. Treatments included: control, heavy metal mix in 1x and 10x concentration with and without EDTA. Each treatment was done on five replicate pots. Treatments were given once in 10 days for one month. At the end of the experiment, roots and shoots were collected, dried, powdered and used for the measurement of heavy metals. In conclusion, amendment of soil with EDTA enhanced uptake of heavy metals when mixture of heavy metals were introduced to the growth medium. The results indicate that Barley, Alfalfa, Mustard and Atriplex plants can be efficiently used for remediation of soil contaminated with heavy metals mainly originating from crude oil spills.
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Evolution of tolerance to one or more metals enables plant species to colonise naturally metalenriched soils. In the phylogeny of angiosperms, the evolution of high metal tolerance is not homogeneously distributed over taxonomic groups and shows differences not only within a taxonomic group, but even among populations of the same species. Anthropogenic metal emissions have pressed plants from non-metalliferous soils to evolve de novo metal tolerances that are predominantly realised in grasses. In this review, information is presented on the evolution of metal tolerance in angiosperms, its time scale and its physiological consequences.
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The concepts of plant diversity vulnerability are re-contextualized relative to global changes. The scope of the study is on an exceptional area, the rocky peri-urban coastline of Marseille (included in the Calanques National Park) where remarkable and threatened plant communities, named littoral phryganas, can be found. Human habitat destruction and/or degradation generated restricted and fragmented distribution of their populations associated with a high local demographic regression (near absence of recruitment, low reproductive success, high individual necrosis generated by salted / polluted sprays and important inter- specific competition by co-occurrent plants). Face to historical and actual phryganas vulnerability, questions on the impact of a potential rise of sea level and a deconstructed rocky coastline are addressed in an ecological perspective, rarely heard in debates concerning the set-back line strategy. The answers suggest in situ and ex situ management measures but also emerge new questions about the relationship of reciprocity between "urban" and "natural" systems based on a new notion of "living together" in order to effective land management. This is a reminder that it is crucial to combine ecological, social and economic factors in shaping a societal dialogue around issues of biodiversity and implementing concrete actions to habitat conservation.
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Five new species of Cyclanthera are here described: C. cogniauxii from the Central Cordillera of Costa Rica; C. dieterleana from Durango, Mexico; C. dioscoreoides with a disjunct distribution in México, Mexico, and Suchitepéquez, Guatemala; C. entata from Chiapas, Mexico; and C. heiseri from Durango, Sinaloa, and Jalisco in Mexico.
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a b s t r a c t The legacy of industrialization has left many soils contaminated. However, soil organisms and plant communities can thrive in spite of metal contamination and, in some cases, metabolize and help in remediation. The responses of plants and soil organisms to contamination are mutually dependent and dynamic. Plantesoil feedbacks are central to the development of any terrestrial community; they are ongoing in both contaminated and healthy soils. However, the theory that governs plantesoil feedbacks in healthy soils needs to be studied in contaminated soils. In healthy soils, negative feedbacks (i.e. pathogens) play a central role in shaping plant community structure. However to our knowledge, the nature of feedback relationships has never been addressed in contaminated soils. Here we review literature that supports a plantesoil feedback approach to understanding the ecology of metal-contaminated soil. Further, we discuss the idea that within these soils, the role of positive as opposed to negative plantesoil feedbacks may be more important. Testing this idea in a rigorous way in any ecosystem is challenging, and metal contamination imposes an additional abiotic constraint. We discuss research goals and experimental approaches to study plantesoil interactions applicable to metal-contaminated soils; these insights can be extended to other contaminated environments and restora-tion efforts.
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Elements uptake, histological distributions as well as mycorrhizal and physiological statuses of Atriplex halimus were determined on trace metal and metalloid polluted soils from the surrounding spray zones of a former lead smelter in the South-East coast of Marseille (France). Analyses of heavy metal and arsenic distribution in soil and plant organs showed that A. halimus tolerance is largely due to exclusion mechanisms. No specific heavy metal concentration in leaf or root tissues was observed. However, accumulation of salts (NaCl, KCl, Mg and Ca salts) on leaf bladders and peripheral tissues of roots was observed and may compete with metal element absorption. Occurrence of endomycorrhizal structures was detected in roots and may contribute to lower element transfer from root into the aerial parts of plants. The non-destructive measurements of leaf epidermal chlorophylls, flavonols and phenols showed a healthy state of the A. halimus population on the metal and metalloid polluted sites. Considering the low metal bioaccumulation and translocation factors along with a reduced metal stress diagnosis, A. halimus appeared as a good candidate for phytostabilization of trace metals and metalloids and notably arsenic in contaminated soils of the Mediterranean spray zone. However, its invasive potential has to be determined before an intensive in situ use.
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Background and aims This is an in natura study aimed to determine the potential of Rosmarinus officinalis for phytostabilization of trace metal and metalloid (TMM)-contaminated soils in the Calanques National Park (Marseille, southeast of France). The link between rosemary tolerance/accumulation of As, Pb, Sb, and Zn and root symbioses with arbuscular mycorrhizal (AM) fungi and/or dark septate endophytes (DSE) was examined. Methods Eight sites along a gradient of contamination were selected for soil and root collections. TMM concentrations were analyzed in all the samples and root symbioses were observed. Moreover, in the roots of various diameters collected in the most contaminated site, X-ray microfluorescence methods were used to determine TMM localization in tissues. Results Rosemary accumulated, in its roots, the most labile TMM fraction in the soil. The positive linear correlation between TMM concentrations in soil and endophyte root colonization rates suggests the involvement of AM fungi and DSE in rosemary tolerance to TMM. Moreover, a typical TMM localization in root peripheral tissues of thin roots containing endophytes forming AM and DSE development was observed using X-ray microfluorescence. Conclusions Rosemary and its root symbioses appeared as a potential candidate for a phytostabilization process of metal-contaminated soils in Mediterranean area.
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A mesocosm experiment was established to evaluate the effect of two organic wastes: fermented sugar beet residue (SBR) and urban waste compost on the stimulation of plant growth, phytoaccumulation of heavy metals (HM) and soil biological quality and their possible use in phytostabilization tasks with native (Piptatherum miliaceum, Retama sphaerocarpa, Bituminaria bituminosa, Coronilla juncea and Anthyllis cytisoides) and non-native (Lolium perenne) plants in a heavy metal-contaminated semiarid soil. Except R. sphaerocarpa, SBR increased the contents of shoot N, P and K and shoot biomass of all plants. The percentage of mycorrhizal colonization was not affected by the organic amendments. The highest increase in dehydrogenase and β-glucosidase activities was recorded in SBR-amended P. miliaceum. SBR decreased toxic levels of HM in shoot of P. miliaceum, mainly decreasing Fe and Pb uptake to plants. This study pointed out that the SBR was the most effective amendment for enhancing the plant performance and for improving soil quality. The combination of SBR and P. miliaceum can be regarded the most effective strategy for being employed in phytostabilization projects of this contaminated site.
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Metalliferous soils provide very restrictive habitats for plants due to phytotoxicity, resulting in severe selection pressures. Species comprising heavy-metal plant communities are genetically altered ecotypes with specific tolerances to, e.g., cadmium, copper, lead, nickel, zinc and arsenic, adapted through microevolutionary processes. Evolution of metal tolerance takes place at each specific site (Ernst 2006). A high degree of metal tolerance depends on the bioavailable fraction of the metal(loids) in the soil and the type of mineralization. At extremely high soil metal concentrations, especially on polymetallic soils, even metal-tolerant genotypes are not able to evolve extreme tolerances to several heavy metals simultaneously. Adapted genotypes are the result of the Darwinian natural selection of metal-tolerant individuals selected from surrounding non-metalliferous populations (Antonovics et al. 1971; Baker 1987; Ernst 2006). Such selection can lead ultimately to speciation and the evolution of endemic taxa. Heavy-metal tolerance was first reported by Prat (1934) in Silene dioica and demonstrated experimentally in grasses by Bradshaw and co-workers in Agrostis spp. and by Wilkins in Festuca ovina in the late 1950s and 1960s (see Antonovics et al. 1971) and from the early 1950s onwards in the herb Silene vulgaris by Baumeister and co-workers (see Ernst 1974). Metal-tolerant plants avoid intoxication by an excess of heavy metals by means of special cellular mechanisms, as long as the soil metal levels do not exceed the levels of metal tolerance (Ernst 1974; Ernst et al. 2004). They can thus thrive on soils that are too toxic for non-adapted species and ecotypes.
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Scattered literature is harnessed to critically review the possible sources, chemistry, potential biohazards and best available remedial strategies for a number of heavy metals (lead, chromium, arsenic, zinc, cadmium, copper, mercury and nickel) commonly found in contaminated soils. The principles, advantages and disadvantages of immobilization, soil washing and phytoremediation techniques which are frequently listed among the best demonstrated available technologies for cleaning up heavy metal contaminated sites are presented. Remediation of heavy metal contaminated soils is necessary to reduce the associated risks, make the land resource available for agricultural production, enhance food security and scale down land tenure problems arising from changes in the land use pattern.
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Ecosystem engineers are organisms that directly or indirectly modulate the availability of resources to other species, by causing physical state changes in biotic or abiotic materials. In so doing they modify, maintain and create habitats. Autogenic engineers (e.g. corals, or trees) change the environment via their own physical structures (i.e. their living and dead tissues). Allogenic engineers (e.g. woodpeckers, beavers) change the environment by transforming living or non-living materials from one physical state to another, via mechanical or other means. The direct provision of resources to other species, in the form of living or dead tissues is not engineering. Organisms act as engineers when they modulate the supply of a resource or resources other than themselves. We recognise and define five types of engineering and provide examples. Humans are allogenic engineers par excellence, and also mimic the behaviour of autogenic engineers, for example by constructing glasshouses. We explore related concepts including the notions of extended phenotypes and keystone species. Some (but not all) products of ecosystem engineering are extended phenotypes. Many (perhaps most) impacts of keystone species include not only trophic effects, but also engineers and engineering. Engineers differ in their impacts. The biggest effects are attributable to species with large per capita impacts, living at high densities, over large areas for a long time, giving rise to structures that persist for millennia and that modulate many resource flows (e.g. mima mounds created by fossorial rodents). The ephemeral nests constructed by small, passerine birds lie at the opposite end of this continuum. We provide a tentative research agenda for an exploration of the phenomenon of organisms as ecosystem engineers, and suggest that all habitats on earth support, and are influenced by, ecosystem engineers.
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The mobilization of heavy metals by man through extraction from ores and processing for different applications has led to the release of these elements into the environment. Since heavy metals are nonbiodegradable, they accumulate in the environment and subsequently contaminate the food chain. This contamination poses a risk to environmental and human health. Some heavy metals are carcinogenic, mutagenic, teratogenic and endocrine disruptors while others cause neurological and behavioral changes especially in children. Thus remediation of heavy metal pollution deserves due attention. Different physical and chemical methods used for this purpose suffer from serious limitations like high cost, intensive labor, alteration of soil properties and disturbance of soil native microflora. In contrast, phytoremediation is a better solution to the problem. Phytoremediation is the use of plants and associated soil microbes to reduce the concentrations or toxic effects of contaminants in the environments. It is a relatively recent technology and is perceived as cost-effective, efficient, novel, eco-friendly, and solar-driven technology with good public acceptance. Phytoremediation is an area of active current research. New efficient metal hyperaccumulators are being explored for applications in phytoremediation and phytomining. Molecular tools are being used to better understand the mechanisms of metal uptake, translocation, sequestration and tolerance in plants. This review article comprehensively discusses the background, concepts and future trends in phytoremediation of heavy metals.
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Soils are faced with man-made chemical stress factors, such as the input of organic or metal-containing pesticides, in combination with non-chemical stressors like soil compaction and natural disturbance like drought. Although multiple stress factors are typically co-occurring in soil ecosystems, research in soil sciences on this aspect is limited and focuses mostly on single structural or functional endpoints. A mechanistic understanding of the reaction of soils to multiple stressors is currently lacking.
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According to most legislative schemes, a soil may require remediation if certain concentrations of one or more heavy metals is exceeded in a designated part (topsoil, subsoil) of the soil profile. A multitude of remediation technologies has been developed for clean-up of heavy-metal-polluted soils (Iskandar and Adriano 1997; Pierzynski 1997). Classic methods, such as excavation, thermal treatment and chemical soil washing are typically expensive and destructive.
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Interactions between organisms are a major determinant of the distribution and abundance of species. Ecology textbooks (e.g., Ricklefs 1984, Krebs 1985, Begon et al. 1990) summarise these important interactions as intra- and interspecific competition for abiotic and biotic resources, predation, parasitism and mutualism. Conspicuously lacking from the list of key processes in most text books is the role that many organisms play in the creation, modification and maintenance of habitats. These activities do not involve direct trophic interactions between species, but they are nevertheless important and common. The ecological literature is rich in examples of habitat modification by organisms, some of which have been extensively studied (e.g. Thayer 1979, Naiman et al. 1988).
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Many rural villages in Eastern Europe are severely impacted by aeolian smelter dust/deposits. Commonly, elemental studies in Romania have suffered from limited sampling numbers (n = 5–10) and/or incomplete di-gestion offering only semi-total quantification of elements using traditional, laboratory-based techniques. These approaches are simply inadequate for evaluating potentially hazardous soils and their spatial extent, particularly at urban/rural interfaces of variable land use. Portable x-ray fluorescence (PXRF) spectroscopy can accurately quantify contamination rapidly, in-situ with a wide dynamic range and little to no sample preparation for analysis of regulated elements (e.g., As, Cd, Cu, Mn, Pb, V, Zn) and other common soil elements such as Ca, Fe, K, Rb, Sr, Ti, and Zr. A contemporary PXRF spectrometer was used to scan 61 soil samples across multiple land use types in urban/rural interfaces on-site. Each site was georeferenced with elemental data inputted into a geo-graphic information system for high resolution kriging interpolation. These models were superimposed over modern aerial imagery to evaluate the extent of pollution for each government-regulated element with simulta-neous consideration and quantification of spatial variability in naturally occurring soil elements. Pb exceeded governmental action limits across 100% of the area, while V, Mn, Cu, and Zn were exceeded in 2.2, 2.1, 39.6, and 9.8% of the area. Furthermore, many regulated elements were closely correlated to natural soil elements. In short, georeferenced PXRF data proved a powerful new tool for on-site assessment of contaminated soils; one which has rarely been utilized in Eastern Europe to date.
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a b s t r a c t Zlatna, Romania is the site of longtime mining/smelting operations which have resulted in widespread metal pollution of the entire area. Previous studies have documented the contamination using traditional methods involving soil sample collection, digestion, and quantification via inductively coupled plasma atomic emission spectroscopy or atomic absorption. However, field portable X-ray fluorescence spec-troscopy (PXRF) can accurately quantify contamination in-situ, in seconds. A PXRF spectrometer was used to scan 69 soil samples in Zlatna across multiple land use types. Each site was georeferenced with data inputted into a geographic information system for high resolution spatial interpolations. These models were laid over contemporary aerial imagery to evaluate the extent of pollution on an individual elemental basis. Pb, As, Co, Cu, and Cd exceeded governmental action limits in >50% of the sites scanned. The use of georeferenced PXRF data offers a powerful new tool for in-situ assessment of contaminated soils.
Article
There are tens of millions of contaminated soil sites in the world, and with an increasing population and associated risk there is a growing pressure to remediate them. A barrier to remediation is the lack of cost-effective approaches to assessment. Soil contaminants include a wide range of natural and synthetic metallic and organic compounds and minerals thus making analytical costs potentially very large. Further, soil contaminants show a large degree of spatial variation which increases the burden on sampling costs. This paper reviews potentially cost-effective methods for measurement, sampling design, and assessment. Current tiered investigation approaches and sampling strategies can be improved by using new technologies such as proximal sensing. Design of sampling can be aided by on-the-go proximal soil sensing; and expedited by subsequent adaptive spatially optimal sampling and prediction procedures enabled by field spectroscopic methods and advanced geostatistics. Field deployment of portable Visible & Near Infrared [wavelength 400–2500 nm] (Vis-NIR) and X-ray fluorescence (PXRF) spectroscopies will require special calibration approaches but show huge potential for synergistic use. The use of mid-infrared spectroscopy [wavelength 2500–25,000 nm, wavenumber 4000–400 cm− 1] (MIR) for field implementation requires further adaptive research. We propose an integrated field-deployable methodology as a basis for further developments.