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Selection of native plants with phytoremediation potential for highly contaminated Mediterranean soil restoration: Tools for a non-destructive and integrative approach
... 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. ...
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.
... We also found some relationships between brownfield characteristics and the delivery of ES. Firstly, studies that explicitly dealt with contaminated brownfields tended to focus more on regulating ES (Fig. 4a), especially on phytoremediation services (Heckenroth et al., 2016;O'Connor et al., 2019;Todd et al., 2016;Wang et al., 2022), while studies that did not report contamination information of the brownfield tended to focus on other services. Secondly, the focus of ES categories differed based on previous land uses. ...
... The primary concern is whether the regenerated space will be directly accessed by people. For example, some spontaneously 'vegetated brownfields', 'protected areas', or 'woodlands and forests' mentioned in the review articles may not undergo full remediation, as these areas are not approached by humans and can be slowly treated by phytoremediation process (Burger, 2008;French et al., 2006;Heckenroth et al., 2016). However, if a brownfield is to be transformed into an urban park or other formal green space, which will be directly used by humans, a "remediation first, then redevelopment" approach should be followed (Loures and Vaz, 2018b). ...
... 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. ...
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.).
... 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). ...
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 strategy performed in this experiment by creating Technosols with MaW and BCh, and allowing the growth of Pm for one year, successfully contributed to the growth of Sr. This species, like other Mediterranean shrubland species, is negatively affected by soil metal (loid) pollution (Heckenroth et al., 2016), and thus a reclamation strategy was needed to decrease metal (loid) toxicity in the soils. The current experiment confirms our initial hypothesis, pinpointing the efficiency of Pm to enable the growth of Sr, although there is also competence when both plants grow together. ...
... Nonetheless, despite the decrease in biomass production, the simultaneous development of Pm and Sr contributed to increase soil organic matter and microbial abundance, suggesting that despite interspecific competition for nutrients, the interaction between these two species positively affects soil quality, stimulating microbial communities and reducing long-term metal toxicity. In this line, Heckenroth et al. (2016) reported that Sr is a promising phytostabilisation-competent species under Mediterranean conditions, but needs the facilitation provided by the growth of other species to reduce metal availability. With the results derived from our study, we would also add not only the reduction of metal availability, but also the stimulation of microbial communities. ...
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.
... 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 ). ...
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.
... So far, only a few legume species (Fabaceae) have been characterized as metallophytes, including Anthyllis vulneraria [10][11][12], Astragalus spp. [13,14], Coronilla juncea [15], and Lotus corniculatus [11,12]. No hyperaccumulators have been found among the species of Fabaceae, though [16]. ...
The aim of the present study was to explore heavy metal tolerance and accumulation potential in Anthyllis vulneraria subsp. maritima plants from coastal sand dunes in controlled conditions. Plants were established from seeds collected in coastal sand dunes and cultivated in substrates in greenhouse conditions. A gradual treatment with CdCl2, PbOAc, CuSO4, MnSO4, and ZnSO4 was performed until three final concentrations for each metal were reached. The number of leaves, their biomass, and biomass of roots were negatively affected by increasing concentrations of lead (Pb) and manganese (Mn) in substrate, but no negative effect was evident for cadmium (Cd), copper (Cu), and zinc (Zn). Visible effects of metal toxicity were evident for Pb-treated plants (appearance of thinner leaves, yellowing of older leaves), as well as for Mn-treated plants (reduced leaf size, curled leaves, red leaf venation). There was a significant decrease in water content in old leaves at high Pb and increasing Mn concentration, indicating accelerated leaf senescence. Increase in polyphenol oxidase activity in leaves was evident in all the plants treated with heavy metals. In contrast, an increase in peroxidase activity was evident only for plants treated with 50 and 100 mg L−1 Cd, 500 mg L−1 Pb, 200–1000 mg L−1 Mn, and 500 mg L−1 Zn. Metal accumulation potential for Cd and Cu was the highest in the roots, but for Pb, Mn, and Zn, more metal accumulated in old leaves. It can be concluded that A. vulneraria subsp. maritima plants are tolerant to high Cd, Cu, and Zn, but moderately susceptible to Pb and Mn. However, oxidative enzyme activity cannot be unequivocally used as a specific indicator of metal tolerance. In respect to phytoremediation potential, the plants have very good accumulation capacity for Pb, Mn, and Zn.
... It has been reported that for phytoremediation studies, herbaceous species are one of the most evaluated plants [9,82] due to their rapid growth, large amount of biomass, strong resistance, and effective stabilization of soils [83]. Also, they are pioneer plants and usually are adapted to unfavorable conditions such as low soil-nutrient content, stressful environments, and shallow soils [51,84,85]. However, in most of the studies that have evaluated the bioaccumulation of HMs in plants, species belonging to the Brasicaceae family have been selected, a herbaceous group that inhabits temperate and cold zones. ...
Citation: Santoyo-Martínez, M.; Mussali-Galante, P.; Hernández-Plata, I.; Valencia-Cuevas, L.; Rodríguez, A.; Castrejón-Godínez, M.L.; Tovar-Sánchez, E. Phytoremediation Potential of Crotalaria pumila (Fabaceae) in Soils Polluted with Heavy Metals: Evidence from Field and Controlled Experiments. Plants 2024, 13, 1947. https://doi. Abstract: Phytoremediation is a useful, low-cost, and environmentally friendly alternative for the rehabilitation of heavy-metal-contaminated (HM) soils. This technology takes advantage of the ability of certain plant species to accumulate HMs in their tissues. Crotalaria pumila is a herbaceous plant with a wide geographical distribution that grows naturally in environments polluted with HMs. In this work, the bioaccumulation capacity of roots and leaves in relation to five HMs (Cr, Cu, Fe, Pb, and Zn) was evaluated, as well as the morphological changes presented in C. pumila growing in control substrate (without HMs) and mine-tailing substrate (with HMs) under greenhouse conditions for 150 days. Four metals with the following concentration pattern were detected in both tissues and substrates: Fe > Pb > Cu > Zn. Fe, Pb, and Zn concentrations were significantly higher in the roots and leaves of individuals growing on mine-tailing substrate compared to the control substrate. In contrast, Cu concentration increased over time in the exposed individuals. The bioconcentration factor showed a similar pattern in root and leaf: Cu > Fe > Pb > Zn. Around 87.5% of the morphological characters evaluated in this species decreased significantly in individuals exposed to HMs. The bioconcentration factor shows that C. pumila is efficient at absorbing Cu, Fe, and Pb from the mine-tailing substrate, in the root and leaf tissue, and the translocation factor shows its efficiency in translocating Cu from the roots to the leaves. Therefore, C. pumila may be considered as a HM accumulator plant with potential for phytoremediation of polluted soils with Cu, Pb, and Fe, along with the ability to establish itself naturally in contaminated environments, without affecting its germination rates. Also, it exhibits wide geographical distribution, it has a short life cycle, exhibits rapid growth, and can retain the mine-tailing substrate, extracting HMs in a short time.
... The recovery of impacted environments by mining may be a challenge due to the rigorous conditions imposed by the degraded environment, such as increased concentration of pollutants, high solar radiation, low aggregation or soil compaction, and low vegetation cover (Ettler et al. 2014;Mukhopadhyay et al. 2016;Pourret et al. 2016). These modifications limit the establishment of less tolerant species or species without specific adaptations (Ginocchio et al. 2017;Heckenroth et al. 2016;Lu et al. 2017;Padilla et al. 2009). Several studies have been carried out with the aim of mitigating these impacts (Funk et al. 2008;Montoya et al. 2012;Laughlin 2014;Lu et al. 2017). ...
Lithium (Li) exploitation promotes socioeconomic advances but may result in harmful environmental impacts. Thus, species selection for recovering environments degraded by Li mining is essential. We investigated the tolerance and early growth of four tree species to Li ore tailings (LOT), Enterolobium contortisiliquum and Handroanthus impetiginosus with wide geographic distribution and Hymenaea courbaril and H. stigonocarpa with restricted geographic distribution. The plants grew in LOT and soil for 255 days to evaluate photosynthesis, growth, and mineral nutrition. LOT negatively affected species growth, reducing the length of stems, roots, and biomass through structural and nutritional impoverishment. LOT favored the accumulation of Mg and decreased the absorption of K. The species presented a reduction in potential quantum efficiency and the chlorophyll index (b and total). E. contortisiliquum was the least tolerant species to LOT, and H. courbaril and H. stigonocarpa maintained their mass production in LOT, indicating greater tolerance to tailings. Furthermore, H. courbaril presented a translocation factor > 1 for Li and Mn, indicating the potential for phytoextraction of these metals. Our results offer first-time insights into the impacts of LOT on the early development of tree species with different geographic distribution ranges. This study may help in the tree species selection with a phytoremediation role, aiming at the recovery of areas affected by Li’s mining activity.
... It has been reported that for phytoremediation studies, herbaceous species are one of the most evaluated plants [9,82] due to their rapid growth, large amount of biomass, strong resistance, and effective stabilization of soils [83]. Also, they are pioneer plants and usually are adapted to unfavorable conditions such as low soil-nutrient content, stressful environments, and shallow soils [51,84,85]. However, in most of the studies that have evaluated the bioaccumulation of HMs in plants, species belonging to the Brasicaceae family have been selected, a herbaceous group that inhabits temperate and cold zones. ...
Phytoremediation is a useful, low-cost, and environmentally friendly alternative for the rehabilitation of heavy-metal-contaminated (HM) soils. This technology takes advantage of the ability of certain plant species to accumulate HMs in their tissues. Crotalaria pumila is a herbaceous plant with a wide geographical distribution that grows naturally in environments polluted with HMs. In this work, the bioaccumulation capacity of roots and leaves in relation to five HMs (Cr, Cu, Fe, Pb, and Zn) was evaluated, as well as the morphological changes presented in C. pumila growing in control substrate (without HMs) and mine-tailing substrate (with HMs) under greenhouse conditions for 150 days. Four metals with the following concentration pattern were detected in both tissues and substrates: Fe > Pb > Cu > Zn. Fe, Pb, and Zn concentrations were significantly higher in the roots and leaves of individuals growing on mine-tailing substrate compared to the control substrate. In contrast, Cu concentration increased over time in the exposed individuals. The bioconcentration factor showed a similar pattern in root and leaf: Cu > Fe > Pb > Zn. Around 87.5% of the morphological characters evaluated in this species decreased significantly in individuals exposed to HMs. The bioconcentration factor shows that C. pumila is efficient at absorbing Cu, Fe, and Pb from the mine-tailing substrate, in the root and leaf tissue, and the translocation factor shows its efficiency in translocating Cu from the roots to the leaves. Therefore, C. pumila may be considered as a HM accumulator plant with potential for phytoremediation of polluted soils with Cu, Pb, and Fe, along with the ability to establish itself naturally in contaminated environments, without affecting its germination rates. Also, it exhibits wide geographical distribution, it has a short life cycle, exhibits rapid growth, and can retain the mine-tailing substrate, extracting HMs in a short time.
... In the regions where mines are abandoned, governmental authorities are faced with the challenge of finding solutions to mitigate the deleterious effects of mining activities and metal pollution, as well as to develop the local economy, which has been deprived of past mining incomes. Phytoremediation is a costeffective and environmentally friendly strategy that can provide ecological solutions for contaminated sites, but can also contribute to the development of socio-economic alternative solutions for local communities (Heckenroth et al. 2016;Zine et al. 2020). Several studies have highlighted the ability of some medicinal and aromatic plants (MAP) to tolerate high levels of heavy metals and limit HM translocation and accumulation in aerial parts (Angelova et al. 2015;Hassan 2016;Malinowska and Jankowski 2017;Ng et al. 2020;Stancheva et al. 2014), for example, Dactylis glomerata, Chrysopogon zizanioides (L.) Roberty and Vetiveria zizanioides (L.) Nash, Cymbopogon citratus (DC.) ...
Peganum harmala L., commonly known as Harmal, is an aromatic and medicinal plant that grows in North Africa. P harmala is a pseudometallophyte that occur both in heavy metals contaminated and non contaminated soils. In order to identify the best adapted and suitable populations within P. harmala species, a comprehensive analysis and evaluation of the morphological, physiological, and biochemical responses to lead (Pb) and zinc (Zn) were performed in three metallicolous populations (MP) and a non-metallicolous one (NMP). In Zaida, Mibladen, and Aouli Morrocan sites, P. harmala growing soils show a low organic matter content, high Pb and Zn concentrations, and a pollution index higher than 1, indicating a significant contamination level. The effects of Pb and Zn on growth, physiological, antioxidant enzyme activities, and Pb/Zn accumulation capacity were compared between a NMP and three MP of P. harmala. Plants were grown in hydroponic culture with 100 mM of ZnSO 4 or 100 mM of Pb(NO 3) 2 for 15 days. Our results show that Pb and Zn significantly decreased the aboveground biomass in the NMP, MP-Mibladen, and MP-Aouli compared to MP-Zaida. Pb and Zn decreased significantly the root biomass in the NMP compared to the MP. There is no significant difference in chlorophyll a and b contents between NMP and MP. Under Pb exposure, anthocyanin content is shown to be significantly higher in MP-Zaida than in other populations. In contrast, there is no difference between NMP and MP under Zn stress. Proline content as well as the catalase, peroxidase, and ascorbate per-oxidase activities was significantly higher in NMP than in MP under Pb and Zn exposure. In particular, lower proline content, and antioxidant activities were observed in MP-Zaida under the Pb and Zn exposure. Pb and Zn accumulations were significantly higher in the NMP than in the MP, both in roots and aboveground parts, showing that the NMP plants accumulated highly but tolerated less compared to the MP. In the present study, the MP-Zaida accumulated less Pb and Zn in their tissues and tolerated more than the other populations, suggesting this population as a good candidate for a phytostabilization strategy.
... Vegetation destruction and functional declines are widely observed in degraded ecosystems. Ecological restoration techniques, such as prescribed fires, soil remediation, phytoremediation, and novel microorganism exploration and utilisation are powerful tools to restore disturbed terrestrial ecosystems and assist plant development (Heckenroth et al., 2016;Wubs et al., 2016;Zhang et al., 2016;Liang et al., 2020;van der Heyde et al., 2020;Mantgem et al., 2021). In forest ecological restoration, 'ponderosa pine' had a high occurrence frequency and has received continuous attention. ...
... Phytoremediation is a green sustainable technique that employs plants to remove toxins from the natural environment. It is an excellent alternative technique to the current physicochemical treatment technologies for wastewater, which is viewed as reliable, cost-effective, creative, environmentally sustainable, broadly supported (Heckenroth et al. 2016). ...
This study was conducted to investigate wastewater phytoremediation under different conditions. We examined the potential of Lemna minor and Pistia stratiotes in two proposed models in natural and artificial plant environment conditions and in previous studies (laboratory pilot-scale study). Before and after treatment, heavy metals, physical and chemical characteristics of wastewater and removal efficiency were analyzed. The results showed that in artificial conditions, Lemna minor reduced pollutants with efficiencies ranging from 90.3 to 98.06% for biological oxygen demand, chemical oxygen demand, total dissolved solids, salinity, conductivity, turbidity, total phosphorus, and total nitrogen, with an increase in saturated oxygen concentration of 82.9%. In natural conditions, the reduction efficiencies ranged from 55.9 to 89.9%, with an increase in saturated oxygen concentration of 67.2%. Conversely, in artificial conditions, Pistia stratiotes achieved removal efficiencies ranging from 93.2 to 98.9%, with an increase in saturated oxygen concentration of 83.6%. Efficiencies ranged from 70.1 to 91.9% in natural conditions. Similarly, the percentages of metals removal by Pistia stratiotes ranged from 71.4 to 97.8% for Fe, Ni, Pb, Cd, Zn, Co, and Cu in artificial conditions and from 37.9 to 79.8% in natural conditions. In addition, metal removal percentages by Lemna minor ranged from 89.6 to 96.4% in artificial conditions and from 27.9 to 60.1% in natural conditions.
... In addition to the pollution resistant through higher disposal efficiency or have more metal(loid) accumulation and resistance to stressful prevailing conditions than plants grown in non-contaminated areas. Many native plant species have been identified and selected as potential phytoremediation plants to extract or stabilize metal(loid)s in impacted mines, for example, Salsola soda [23], Salsola, Eremopyrum, Aeluropus litoralis [24], Salsola oppositifolia Desf, Limonium delicatulum, Moricandia arvensis (L.) DC [18], Piptatherum caerulescens, Coris monspeliensis, Lobularia maritima [25] and Pinus halepensis, and Tetraclinisarticulata [26]. However, there are very few studies that evaluate the potential of native plants to be used in phytoremediation programs in soils affected by polymetallic contamination, including heavy metals as well as metalloids and rare earth elements. ...
Mining activity has an adverse impact on the surrounding ecosystem, especially via the release of potentially toxic elements (PTEs); therefore, there is an urgent need to develop efficient technologies to remediate these ecosystems, especially soils. Phytoremediation can be potentially used to remediate contaminated areas by potentially toxic elements. However, in soils affected by polymetallic contamination, including metals, metalloids, and rare earth elements (REEs), it is necessary to evaluate the behavior of these toxic elements in the soil-plant system, which will allow the selection of the most appropriate native plants with phytoremediation potential to be used in phytoremediation programs. This study was conducted to evaluate the level of contamination of 29 metal(loid)s and REEs in two natural soils and four native plant species (Salsola oppositifolia, Stipa tenacissima, Piptatherum miliaceum, and Artemisia herba-alba) growing in the vicinity of a Pb-(Ag)-Zn mine and asses their phytoextraction and phytostabilization potential. The results indicated that very high soil contamination was found for Zn, Fe, Al, Pb, Cd, As, Se, and Th, considerable to moderate contamination for Cu, Sb, Cs, Ge Ni, Cr, and Co, and low contamination for Rb, V, Sr, Zr, Sn, Y, Bi and U in the study area, dependent of sampling place. Available fraction of PTEs and REEs in comparison to total concentration showed a wide range from 0% for Sn to more than 10% for Pb, Cd, and Mn. Soil properties such as pH, electrical conductivity, and clay content affect the total, available, and water-soluble concentrations of different PTEs and REEs. The results obtained from plant analysis showed that the concentration of PTEs in shoots could be at a toxicity level (Zn, Pb, and Cr), lower than toxic but more than sufficient or natural concentration accepted in plants (Cd, Ni, and Cu) or at an acceptable level (e.g., V, As, Co, and Mn). Accumulation of PTEs and REEs in plants and the translocation from root to shoot varied between plant species and sampling soils. A. herba-alba is the least efficient plant in the phytoremediation process; P. miliaceum was a good candidate for phytostabilization of Pb, Cd, Cu, V, and As, and S. oppositifolia for phytoextraction of Zn, Cd, Mn, and Mo. All plant species except A. herba-alba could be potential candidates for phytostabilization of REEs, while none of the plant species has the potential to be used in the phytoextraction of REEs.
... Moreover, halophytes for important bioactive metabolites with commercial value may be cultivated for food, fodder, forage, fuel, and medicinal crops on saline lands [6][7][8][9][10][11][12][13][14][15][16][17]. Hence, halophytes can be used as alternative crops and may be potential candidates for phytoremediation [19]. However, careful selection of species is needed as some of them may accumulate higher concentrations of trace metals in their edible parts, more specifically in leaves [20]. ...
Plants in coastal ecosystems are primarily known as natural sinks of trace metals and their importance for phytoremediation is well established. Salvadora persica L., a medicinally important woody crop of marginal coasts, was evaluated for the accumulation of metal pollutants (viz. Fe, Mn, Cu, Pb, Zn, and Cr) from three coastal areas of Karachi on a seasonal basis. Korangi creek, being the most polluted site, had higher heavy metals (HM's) in soil (Fe up to 17,389, Mn: 268, Zn: 105, Cu: 23, Pb: 64.7 and Cr up to 35.9 mg kg −1) and S. persica accumulated most of the metals with >1 TF (translocation factor), yet none of them exceeded standard permissible ranges except for Pb (up to 3.1 in roots and 3.37 mg kg −1 in leaves with TF = 11.7). Seasonal data suggested that higher salinity in Clifton and Korangi creeks during pre-and post-monsoon summers resulted in lower leaf water (ΨWo) and osmotic potential at full turgor (ΨSo) and bulk elasticity (ε), higher leaf Na + and Pb but lower extractable concentrations of other toxic metals (Cr, Cu, and Zn) in S. persica. Variation in metal accumulation may be linked to metal speciation via specific transporters and leaf water relation dynamics. Our results suggested that S. persica could be grown on Zn, Cr and Cu polluted soils but not on Pb affected soils as its leaves accumulated higher concentrations than the proposed limits .
... This is because native species are adapted to the climatic and soil conditions of the area to be cleaned. In recent years, many studies have been performed on the suitability of different native plant species for the phytoremediation of heavy metal-contaminated areas [25,41,42]. Most studies have focused on grasses, which are pioneers in colonizing devastated areas [43][44][45][46]. ...
The aim of the study was to compare the phytoremediation potential of cultivated grasses with local wild grass for soil contaminated with zinc. Two pot experiments were carried out on soil artificially contaminated with Zn. Four species of cultivated grasses were used as test plants: Poa pratensis, Lolium perenne, Festuca rubra, Festuca pratensis, and one wild, native grass: Deschampsia caespitosa. Wild grass seeds were collected from soil contaminated with heavy metals near a zinc smelter. The phytoremediation potential of grasses was determined on the basis of the tolerance index (TI), bioaccumulation (BF), and translocation (TF) factors. Differences were found between the species in the reduction in the shoot and root biomass with increasing soil contamination with Zn. The tolerance of the studied grasses to excess Zn in the soil was in the following order: D. caespitosa > L. perenne > F. rubra > F. pratensis > P. pratensis. In addition, there were differences in the accumulation and distribution of Zn between the roots and shoots, which is related to the different defense mechanisms of the studied grasses against Zn phytotoxicity. Of the five grasses tested, the highest phytoremediation potential was shown by D. caespitosa. This grass had a significantly higher tolerance to Zn and a lower transfer of Zn from the roots to shoots than the other cultivated grasses tested. All four cultivated grasses can be useful for phytostabilization because they accumulated Zn mainly in the roots and limited its translocation to the shoots. Unlike wild grass seeds, cultivated grass seeds are readily available commercially and can be used for the phytoremediation of HM-contaminated sites.
... Selective breeding has steadily contributed to the genetic enhancement of crop plants during recent centuries. The artificial selection process is addressed to strengthen specific traits, such as yield, tolerance/resistance to phytopathogens and abiotic stress conditions, organoleptic properties, chemical composition, etc. (Heckenroth et al., 2016). However, during the selection process, some favourable or unfavourable traits may be unintentionally lost or selected (Tanksley and McCouch, 1997), including traits possibly involved in the contamination of produce by human pathogens. ...
... As an inexpensive, highly efficient, and green technology, phytostabilization has been widely considered for its potential research and practical repair applications. Yet, additional research is still needed to determine a shortlist of plants that are resistant to heavy metals for the ecological restoration of contaminated areas [33]. ...
Phytoremediation could be an alternative strategy for lead (Pb) contamination. K. paniculata has been reported as a newly potential plant for sustainable phytoremediation of Pb-contaminated soil. Physiological indexes, enrichment accumulation characteristics, Pb subcellular distribution and microstructure of K. paniculata were carefully studied at different levels of Pb stress (0–1200 mg/L). The results showed that plant growth increased up to 123.8% and 112.7%, relative to the control group when Pb stress was 200 mg/L and 400 mg/L, respectively. However, the average height and biomass of K. paniculata decrease when the Pb stress continues to increase. In all treatment groups, the accumulation of Pb in plant organs showed a trend of root > stem > leaf, and Pb accumulation reached 81.31%~86.69% in the root. Chlorophyll content and chlorophyll a/b showed a rising trend and then fell with increasing Pb stress. Catalase (CAT) and peroxidase (POD) activity showed a positive trend followed by a negative decline, while superoxide dismutase (SOD) activity significantly increased with increasing levels of Pb exposure stress. Transmission electron microscopy (TEM) showed that Pb accumulates in the inactive metabolic regions (cell walls and vesicles) in roots and stems, which may be the main mechanism for plants to reduce Pb biotoxicity. Fourier transform infrared spectroscopy (FTIR) showed that Pb stress increased the content of intracellular -OH and -COOH functional groups. Through organic acids, polysaccharides, proteins and other compounds bound to Pb, the adaptation and tolerance of K. paniculata to Pb were enhanced. K. paniculata showed good phytoremediation potential and has broad application prospects for heavy metal-contaminated soil.
... Research has clearly shown that the achievement of successful phytoremediation depends on plant selection, plant growth rate, contaminants translocation, accumulation potential, and tolerance to pollutants [16,[19][20][21][22]. However, there is a lot of potential to learn about plant species capacity for phytoremediation [23]. Despite the fact that there is a wealth of research on the remediation of soil contaminants, edible plants also have great potential for phytoremediation [24][25][26]. ...
Plant-based strategies could provide a key gateway to restoring heavy metal-polluted environments. The present study was aimed to investigate the phytoremediation potential of Vigna radiata (L.) Wilczek in the heavy metal contaminated regions by oil industries at West Karun River, Iran. After soil sampling, the plants were grown in pots outdoors and irrigated by distilled water (0 mg/L Cd), Karun River water (0.04 mg/L Cd), and also by 25, 50, 75, and 100 mg/L of cadmium chloride solutions. Plants were harvested at the seedling and ripening stages and their Cadmium (Cd) content was determined. According to the results, the efficiency of V. radiata for bioaccumulation of Cd was very high at low concentrations of Cd in Karun River treatments (57% and 21% for shoot and roots, respectively), the highest Transfer Coefficient (TC) was (2.80 ± 0.5), Translocation Factor (TF) (2.78 ± 0.7), and Bioaccumulation Factor (BF) (3.83 ± 0.4). Although our findings shows that V. radiata does not possess a high potential of Cd phytoremediation at high concentrations (2.47% and 4.21% in shoot and roots at 50–100 mg/L Cd, respectively), it can provide a safe alternative based at minimum level of Cd concentration. Comparison of heavy metal contents in mung bean plants and soil, shows that there is an antagonistic relationship in Cd uptake and other accessible heavy metals such as Iron (Fe), Zinc (Zn), and Copper (Cu) from the soil at the study area. Thus the V. radiata could be considered as a potent candidate for bioremediation and growing food in Cd-polluted environments.
... 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 . ...
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.
... Selective breeding has steadily contributed to the genetic enhancement of crop plants during recent centuries. The artificial selection process is addressed to strengthen specific traits, such as yield, tolerance/resistance to phytopathogens and abiotic stress conditions, organoleptic properties, chemical composition, etc. (Heckenroth et al., 2016). However, during the selection process, some favourable or unfavourable traits may be unintentionally lost or selected (Tanksley and McCouch, 1997), including traits possibly involved in the contamination of produce by human pathogens. ...
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.
... 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. ...
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.
... applications. Yet, additional research is still in need to short-list plants that are resistant to heavy metals for ecological restoration of contaminated areas (Heckenroth et al. 2016). ...
Phytoremediation could be an alternative strategy for lead (Pb) contamination, The physiological mechanisms of plant resistance to Pd contamination are of less concern. In this study, Different concentrations of Pb solutions were added to explore the growth of Koelreuteria paniculate (Sapindaceae). physiology and microstructure of K. paniculate were determined. The results showed that plant growth increased up to 123.8% and 112.7% relative to the control group when the lead concentration was 200 and 400 mg/L. In all treatments, most of the Pb accumulation reached 81.31%-86.69% in the roots and slightly lower concentrations in the above-ground leaves than in the stems. Transmission electron microscopy (TEM) showed that Pb accumulates in the inactive metabolic parts (cell walls and vesicles) in roots and stems, which may be the main mechanism for plants to reduce Pb biotoxicity. In addition, by Fourier transform infrared spectroscopy (FTIR), Pb stress increased the content of intracellular -OH and -COOH functional groups, including compounds such as organic acids, polysaccharides and proteins that bind to Pb, attenuating the toxicity to plants and enhancing their adaptation and tolerance to heavy metals.
... 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]. ...
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.
... 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). ...
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.
... 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). ...
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.
... 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). ...
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.
... 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]. ...
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.
... 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). ...
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.
... 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]. ...
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).
... 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]. ...
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.
Citation: Boi, M.E.; Sarigu, M.; Fois, M.; Casti, M.; Bacchetta, G. The First Inventory of Sardinian Mining Vascular Flora. Plants 2025, 14, 1225. Abstract: Mining activities and associated waste materials pose significant environmental challenges, including soil, water, and air contamination, along with health risks to nearby populations. Despite the harsh conditions of metal-enriched soils and nutrient-poor sub-strates, certain plants known as metallophytes thrive in these environments. This study examined the vascular flora of Sardinia's abandoned mining sites, with a focus on identifying metallophytes and their potential role in phytoremediation. A comprehensive floristic checklist was compiled using literature, field surveys, and herbarium samples. Of the 652 taxa identified, 49% were metallophytes, with the majority categorized as facultative species. Notably, 27% of metallophytes were identified as suitable for phytostabilization, while 20% showed potential for phytoextraction. This study also highlighted the presence of endemic and endangered species, emphasizing the need for conservation efforts. The findings suggest that native metallophytes could play a key role in the ecological restoration of mining sites, though careful consideration of invasive species is necessary to avoid ecological disruption. This research provides valuable insights into the biodiversity of Sardinian mining sites and the potential for sustainable remediation strategies using native plants.
Phytoremediation refers to the use of plants to remove or stabilize environmental contaminants in an environment. It is regarded as a highly effective and inexpensive method in countering heavy metal pollution. This paper examines the feasibility of using native plants in phytoremediation through the demonstration of their sensitivity, survivability, and tolerance towards the local environmental condition and their capability to accumulate and tolerate contaminants such as lead, cadmium, and arsenic. Native species have various advantages that include lesser upkeep requirements, improved ecosystem incorporation, and least invasive danger. The mechanisms involved in phytoremediation range from phytoextraction, Phyto stabilization, and rhizofiltration to the specific roles played by native plants in remediation processes of soil and water. Case studies are presented to demonstrate the successful use of native species at various contaminated sites. Challenges related to scalability and ecological risks are addressed. Emerging trends, including biochar amendments, genetic modification, and expanded applications into urban areas, suggest promising future directions.
Mining exploitation in the Mediterranean Basin has left evident scars on the environment, and poses serious risks for human health and biodiversity, especially when mine wastes are left abandoned. This review analysed the main issues of metal(loid)s pollution related to mine exploitation in the Mediterranean Basin. Here, a list of Mediterranean native plant species studied for phytoremediation is given and, considering their biological forms, vegetational types, and ecology, we categorised them into halotolerant and hydro/hygrophilous vegetation, annual and perennial meadows, garrigues and maquis, and high maquis and woods. The main conclusions of the review are as follows: (1) plant communities established on mine environments are often rich in endemic taxa which ensure a high biodiversity and landscape value, and can help in the psychophysical health of local inhabitants; (2) political and land management should take greater account of the use of native plants for the remediation of contaminated soils; (3) a multidisciplinary approach that includes, among others, studies on biochemical response to metal(loid)s as well as the application of innovative soil amendments gives better results; (4) phytoextraction applications require a detailed recovery plan that takes into consideration several issues, including the negative influence on biodiversity due to extensive use of monotypic plantations, disposal of harvested hazardous plants, and the risk of phytoextracts entering the food chain; and (5) more studies are necessary to increase knowledge and to detect suitable species—especially halophytic ones—for phytoremediation purposes.
The management of mine tailings (MT) is commonly workload heavy, intrusive, and expensive. Phytostabilization offers a promising approach for MT management; however, it poses challenges due to the unfavorable physicochemical properties of these wastes. Nevertheless, native microorganisms capable of supporting plant growth and development could enhance the efficacy of phytostabilization. This study assesses the biological activity of microbial communities from the root zone of Baccharis linearis, which is naturally present in MT, in order to evaluate their biotechnological potential for phytostabilization. The root zone and bulk samples were collected from B. linearis plants located within a MT in the Mediterranean zone of Chile. Enzyme activities related to the cycling of C, N, and P were assessed. The community-level physiological profile was evaluated using the MicroRespTM system. Bacterial plant growth-promoting (PGP) traits and colony forming units (CFU) were evaluated through qualitative and microbiological methods, respectively. CFU, enzyme activities, and CLPP were higher in the root zone compared with the bulk samples. Five bacterial strains from the root zone exhibited PGP traits such as P solubilization and N acquisition, among others. The presence of microbial communities in the root zone of B. linearis with PGP traits suggests their potential to enhance the ecological management of MT through phytostabilization programs.
Despite increasing metals and metalloids (MM) human-driven soil contamination, how it simultaneously alters biodiversity and ecosystem functioning remains unknown. We used a wide gradient of a 170-year-old MM soil multi-contamination in Mediterranean scrublands to assess the effects of soil multi-contamination on multiple plant biodiversity facets, microbial communities and ecosystem multifunctionality (EMF). We found an overall positive effect of plant biodiversity on EMF mediated by microbial communities, and allowing offsetting the negative impacts of MM soil multi-contamination, especially on soil water holding capacity and nitrogen content. The diversity of distant plant lineages was the key facet promoting EMF by enhancing microbial communities, whereas the subordinate species richness altered EMF. By developing a holistic approach of these complex relationships between soil multi-contamination, plant biodiversity, microbial communities and ecosystem functioning, our results reveal the potential of plant biodiversity, and especially the diversity of evolutionary distant species, to offset the alteration of ecosystem functioning by MM soil multi-contamination. In this worldwide decade of ecosystems restoration, our study helps to identify relevant facets of plant biodiversity promoting contaminated ecosystem functioning, which is crucial to guide and optimize management efforts aiming to restore ecosystems and preserve human health.
Phytoremediation using woody plants can effectively reduce heavy metal (HM) concentrations in soils. However, the remediation capacity of woody plants depends greatly on plant species and soil environmental conditions. In order to evaluate the HM remediation potential of woody plants from different tailing areas, the HM accumulation characteristics of roots, shoots, and leaves of 12 dominant native woody plants growing in iron and lead-zinc tailing areas were analyzed. The results showed that the concentrations of Cd, As, Ni, Mn, and Cr in most plants in the two tailing areas exceeded the level of normal plants. The distribution of different elements in plants was generally as follows: root > leaf > shoot for Pb and As; root > shoot > leaf for Cr; and leaf > shoot > root for Zn, Ni, and Mn. The distribution of Cu and Cd in plants varied with the type of HM pollution in the two tailing areas. There were significant (p < 0.05) negative correlations between available phosphorus in the soil and Pb, Cd, and Zn in the plant roots when the soil was heavily polluted with Pb, Cd, and As; similarly, there were significant (p < 0.01) negative correlations between readily available potassium in the soil and Pb, Zn, and Ni in plant roots. Based on the higher than average concentration of HMs in plants, and higher bioconcentration factors and translocation factors, some plants were considered woody plant species with phytoremediation. Slash pine (Pinus elliottii) and indian azalea (Rhododendron simsii) had strong enrichment and translocation abilities for Cd, oriental white oak (Quercus glauca) and beautiful sweetgum (Liquidambar formosana) for Mn and paulownia (Paulownia fortunei) for Zn. The plants listed above can be used as potential species for phytoremediation in iron and lead-zinc tailing areas.
Seabird colonies have a strong influence on both the physical and chemical soil parameters and plant communities of the islands where they settle to nest. Scientists have studied the effects of the demographic explosion of seabird populations, but few have explored the long-term effects when the colonies were in decline. The aim of this study was to investigate diachronic changes over a 24 year period of soil parameters, floristic composition and plant functionnal types (Raunkiaer growth forms and Grime life strategies) up to the decrease of the number of nesting yellow-legged gulls (Larus michahellis Naumann, 1840) on Mediterranean islands. We used 78 permanent plots to survey the vegetation and the soil parameters on 9 islands and one mainland area within the Calanques National Park (south east of France), for three periods (i.e., 1997, 2008, 2021). Since 1997, the increase of nesting gulls has caused a nitrogen and pH increase and organic carbon and C/N ratio decrease, although the values were still higher than mainland plots without nesting gulls. This has led to changes in plant species composition e.g., higher values of N favouring the development of ruderal plant species, still present in high frequency in 2021. Furthermore, plant species highly tolerant to disturbances (i.e., R Grime strategy) in harsh environments were still favoured even after the decline of gull abundance. However, both the frequency of the chamaephytes and the vegetation cover has increased with the decline of gull colony. In 2021, measures of trace elements' concentrations and calculation of pollution load index (Cu, Pb and Zn) reveals relatively low multi-contamination levels on the mainland and the archipelagos. On naturally oligotrophic and semi-arid Mediterranean islands, gull colonies induce a persistent alteration in soil characteristics that still influences plant communities (composition and functional types), 11 years after the decline in bird abundance.
Summary In French law, the principle of ecological solidarity is intended to be implemented when a decision taken by a public authority would have a significant impact on the environment. That is, when the impact has not yet occurred. This interpretation immediately reduces its scope and suggests that it would only apply to areas that have not yet been degraded. Taking the opposite view of the principle, this article demonstrates that the concept of ecological solidarity would also be a driving force in the implementation of measures for the ecological restoration of degraded environments and in particular soils. In doing so, it draws on a field study located in the heart of the Calanques National Park (SynTerCalM project, 2014-2016) to highlight how the inaction toward a degradation that can be invisible, soil contamination, undermines the conservation and restoration objectives of the environments with which it is related.
Green remediation of severely contaminated soils around mining sites can be achieved using suitable woody plants such as Quercus species, but their phytoremediation potential has not been well evaluated yet. Six Quercus species, which were popular in ecological restoration and landscape application in east China, were selected and evaluated for their phytoremediation potential of metal polluted soil using a pot experiment that lasted for 150 d. The results suggested that Quercus species exhibited high tolerance to multi-metal contamination of Cu (9839 mg·kg⁻¹), Cd (8.5 mg·kg⁻¹), and Zn (562 mg·kg⁻¹) with a tolerance index (TI) ranging from 0.52 to 1.21. Three Quercus (Q. pagoda, Q. acutissima, and Q. nuttallii) showed relatively higher tolerance with TIs of 1.08, 1.09, and 1.21, respectively. Above-ground tissues accounted for most of the total biomass in T1 (mixture of clean and polluted soil, 50%) and T2 (100% polluted soil) treatments for most species. The Cu contents in plant tissues were in the order of root > leaf > stem, whereas Zn exhibited the order of leaf > stem > root, and Cd showed divergent mobility within the Quercus species. All the Quercus species exhibited higher capacity for Zn phytoextraction with translocation factor (TF) over 1 and Cu/Cd phytostabilization with TFs lower than 1. The analytic hierarchy process-entropy weight model indicated that Q. virginiana and Q. acutissima were two excellent species with evident phytoremediation capacity of Cu, Cd, and Zn co-contaminated soil. Taken together, Quercus species showed great potential for phytoremediation of soils severely polluted by Cu, Cd, and Zn around historic mining sites. Application of Quercus species is a green remediation option with low-maintenance cost and prospective economic benefit for phytomanagement of historic mining sites.
Phytoremediation using woody plants can effectively reduce heavy metals (HMs) concentrations in soils. However, the remediation capacity of woody plants depends on soil and environmental conditions. To evaluate the HMs remediation potential of woody plants from different mining areas, we analyzed the HMs accumulation characteristics of roots, shoots and leaves of 12 dominant native woody plants in iron and lead-zinc mining areas. The distribution of HMs in plants varied with the type of HMs pollution in the two mining area. Available phosphorus (AP) and available potassium (AK) in soil were potential factors for the uptake of HMs by woody plants. In areas heavily contaminated with Pb, Cd and As, abilities of woody plants to accumulate Pb, Cd and Zn from soil were suppressed by AP, and the abilities to accumulate Pb, Zn, Cr and Ni from soil were suppressed by AK. Cyclobalanopsis glauca and Rhododendron simsii had strong enrichment and translocation abilities for Cd and Mn, Pinus elliottii for Cd, Liquidambar formosana for Mn and Paulownia fortunei for Zn. Castanopsis sclerophylla, Rhus chinensis, Rhododendron simsii, Liquidambar formosana, Photinia × fraseri,and Paulownia fortunei could grow under ultra-high concentration of As. The plants listed above can be used as potential species for phytoremediation in iron and lead-zinc mining areas.
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 vegetation restoration significantly improved soil nutrients. What’s more, compared to PKSZ and PSC, RPL could better improve soil TC, TN, TP, and AP. In addition, soil ectomycorrhizal community diversity in RPL was greater than PKSZ and PSC. NMDS analyses indicated that soil ectomycorrhizal community significantly differed depending on different revegetation types. Thus, these results indicated that RPL could be a suitable species for the revegetation of iron mine tailings. The experiment provided theoretical basis for evidence for ecological restoration of iron mine tailings using local plant species.
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.
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:
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.
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.
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.
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.
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.
We present here a comparison between the outputs of 25 General Circulation Models run for the mid-Holocene period (6 ka BP) with a set of palaeoclimate reconstructions based on over 400 fossil pollen sequences distributed across the European continent. Three climate parameters were available (moisture availability, temperature of the coldest month and growing degree days), which were grouped together using cluster analysis to provide regions of homogenous climate change. Each model was then investigated to see if it reproduced 1) similar patterns of change and 2) the correct location of these regions. A fuzzy logic distance was used to compare the output of the model with the data, which allowed uncertainties from both the model and data to be taken into account. The models were compared by the magnitude and direction of climate change within the region as well as the spatial pattern of these changes. The majority of the models are grouped together, suggesting that they are becoming more consistent. A test against a set of zero anomalies (no climate change) shows that, although the models are unable to reproduce the exact patterns of change, they all produce the correct signs of change observed for the mid-Holocene. 1
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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.
The master plan for a soil clean-up of the former zinc smelter “Pertusola Sud” (Crotone, Italy) considered gentle remediation options for a specific area where both by-products and industrial wastes had been disposed in the past. Although the soil is severely contaminated by metals (Cd, Cu, Ge, Hg, In, Pb, Tl and Zn) and metalloids (As and Sb), several plant species grow spontaneously in this area. Plants and soil samples were collected and analysed for trace element concentrations.In the shoots of Dittrichia viscosa the Cd concentration (112 mg kg−1) exceeded the hyperaccumulation threshold. Phragmites australis and Silene bellidifolia concentrated about 30 and 40 mg kg−1 of Tl in their shoots, respectively. Sb accumulation in leaves of Acacia saligna, Eucalyptus camaldulensis and P. australis was more than 20 times higher than herbs. The highest Zn concentration in shoots was recorded in D. viscosa (1172 mg kg−1). The phytoremediation potential of plants was evaluated considering the concentration of metals and metalloids in the plant tissues and also the bioconcentration factor (BF) and translocation factor (TF). The plant requirements for Sb phytoextraction were verified for P. australis (1.66 BF, TF 9.02), and for E. camaldulensis (BF 1.11, TF 1.71) and Galactites elegans (BF 2.30, TF 1.37) for Tl. Scirpoides holoschoenus could be considered for phytostabilization and recommended to restore a green cover on bare soils at the Pertusola Sud site.
Silene vulgaris ssp. humilis, a heavy metal tolerant plant growing on the polluted soil of a medieval copper mining dump, accumulates considerable amounts of heavy metals (HM) in its roots and shoots. The intracellular distribution of HMs in the leaves was investigated by conventional and analytical (EDX, ESI, EELS) electron microscopy. Part of the HMs, Fe, Cu, and Zn occur as crystalline compounds on the surface of the leaves. The epidermal cell walls accumulate Fe, Ni, Cu, AI, Sn, and Zn. Cu within the cell walls is tightly bound to a protein with oxalate oxidase activity, evidencing a high homology to germin. Zn and Sn are accumulated in the cell walls as silicate. Cytoplasm and organelles contain only traces of Cu and Sn, while in the vacuoles no HMs are detected. In the epidermal cell walls, intercellular spaces, and in vacuoles there are high concentrations of Si, forming crystal-like structures. EELS and quantum-chemical calculations reveal these structures as SiO2. The role of Si in the HM-tolerance of Silene is discussed.
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 spectroscopy (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.
A field survey of higher terrestrial plants growing on 18 metalliferous sites of the Austrian Alps was conducted to identify species accumulating exceptional large concentrations of Cd, Cu, Ni, Pb and Zn in shoots. Minuartia verna (Caryophyllaceae) was confirmed and Biscutella laevigata (Brassicaceae) newly identified as hyperaccumulators of Pb (>1000 mg kg−1 Pb in shoots). Metal concentrations in shoots exceeded those in roots. Cadmium concentrations detected in shoots of Thlaspi rotundifolium ssp. cepaeifolium (up to 108 mg kg−1), Cardaminopsis halleri (up to 80 mg kg−1), Biscutella laevigata (up to 78 mg kg−1) and Minuartia verna (up to 59 mg kg−1) may represent hyperaccumulation. In addition, populations of Thlaspi goesingense (up to 12400 mg kg−1 Ni) and Thlaspi rotundifolium ssp. cepaeifoliium (up to 1934 mg kg−1 Pb) were confirmed to be hyperaccumulators. The strategy of neighboring Thlaspi rotundifolium ssp. cepaeifolium populations to tolerate high Pb and Zn was found to switch from hyperaccumulation at moderate and large, to exclusion at very large metal concentrations in soil. Metal partitioning in soils determined by sequential extraction gives evidence for large proportions of potentially mobile fractions. Metals stored in shoots typically do not exceed the soil metal pool in fractions 1 (exchangeable) and 2 (readily mobile). There is evidence that hyperaccumulation may be associated with depressed translocation of K from roots to shoots. Under natural conditions metals accumulated in shoots are annually recycled to the soil, hyperaccumulators do not necessarily rely on metal phases less soluble than fractions 1 and 2. These should be considered in future development of phytoremediators, because after extraction of these phases by harvesting shoots, further metal removal may be limited by dissolution kinetics of oxides and silicates.
It is suggested that evolution in plants may be associated with the emergence of three primary strategies, each of which may be identified by reference to a number of characteristics including morphological features, resource allocation, phenology, and response to stress. The competitive strategy prevails in productive, relatively undisturbed vegetation, the stress-tolerant strategy is associated with continuously unproductive conditions, and the ruderal strategy is characteristic of severely disturbed but potentially productive habitats. A triangular model based upon the three strategies may be reconciled with the theory of r- and K-selection, provides an insight into the processes of vegetation succession and dominance, and appears to be capable of extension to fungi and to animals.
Phytomanagement in terms of phytostabilisation is considered a suitable method to decrease environmental risks of metal(loid) enriched mine tailings. The goal of this study was to identify plant-favourable edaphic niches in mine tailings from a semiarid area, in order to obtain relevant information for further phytostabilisation procedures. For this purpose, a transect-designed sampling from non-disturbed soils to two mine tailings was performed, including the description of soil and plant ecology gradients. Plant ecological indicators showed several stages in plant succession: from weeds to stable patches of late successional plant species. PCA results revealed that plant distribution at the tailings was driven mainly by salinity while metal(loid) concentrations played a minor role. The presence of soil desiccation cracks generated low salinity patches which facilitated favourable niches for plant establishment. Edaphic-patch distribution may condition phytostabilisation since ploughing or the employment of certain amendments should take into account favourable niches for plant growth.
This study aimed at identifying the extent and type of contamination of a former lead smelting site in the area of Marseille, France, dating from the industrial revolution, and to evaluate environmental hazards and opportunities for phytoremediation, a promising sustainable technology. Amongst the native plants growing in this semiarid shrub ecosystem, two perennials Globularia alypum L. and Rosmarinus officinalis L. were selected. Twenty-one soil/plant couples were collected and seventeen additional soil samples were added to better characterize the soil pollution of the area. A multi-contamination by Pb, As, Sb, Zn, Cu was demonstrated, with huge variations within the contamination levels. The soils highest concentrations were encountered along the horizontal chimney and on the slag heaps area. However, both sites differed from each other. The former was characterized by the highest Pb, As and Sb concentrations that could reach 130, 7.0 and 9.0gkg(-1) respectively, the latter, by high Cu, Fe, Mn, S concentrations, even if it was also heavily contaminated by Pb and Zn. G. alypum and R. officinalis were shown to be metal-tolerant and to accumulate trace metals and As. Due to the low bioconcentration and translocation factors determined, both species may not be used for phytoextraction, but seem to be good candidates for phytostabilization.