Hyperaccumulator Oilcake Manure as an Alternative for Chelate-Induced Phytoremediation of Heavy Metals Contaminated Alluvial Soils

The ability of hyperaccumulator oilcake manure as compared to chelates was investigated by growing Calendula officinalis L for phytoremediation of cadmium and lead contaminated alluvial soil. The combinatorial treatment T₆ [2.5 g kg^?1oilcake manure + 5 mmol kg^?1 EDDS] caused maximum cadmium accumulation in root, shoot and flower up to 5.46, 4.74 and 1.37 mg kg^?1and lead accumulation up to 16.11, 13.44 and 3.17 mg kg^?1, respectively at Naini dump site, Allahabad (S₃). The treatment showed maximum remediation efficiency for Cd (RR = 0.676%) and Pb (RR = 0.202%) at Mumfordganj contaminated site (S₂). However, the above parameters were also observed at par with the treatment T₅ [2.5 g kg^?1oilcake manure +2 g kg^?1 humic acid]. Applied EDDS altered chlorophyll–a, chlorophyll–b, and carotene contents of plants while application of oilcake manure enhanced their contents in plant by 3.73–8.65%, 5.81–17.65%, and 7.04–17.19%, respectively. The authors conclude that Calendula officinalis L has potential to be safely grown in moderately Cd and Pb-contaminated soils and application of hyperaccumulator oilcake manure boosts the photosynthetic pigments of the plant, leading to enhanced clean-up of the cadmium and lead-contaminated soils. Hence, the hyperaccumulator oilcake manure should be preferred over chelates for sustainable phytoremediation through soil-plant rhizospheric process.     

Phytoremediation of Cd,Ni, Pb and Zn by Salvinia minima

Most metals disperse easily in environments and can be bioconcentrated in tissues of many organisms causing risks to the health and stability of aquatic ecosystems even at low concentrations. The use of plants to phytoremediation has been evaluated to mitigate the environmental contamination by metals since they have large capacity to adsorb or accumulate these elements. In this study we evaluate Salvinia minima growth and its ability to accumulate metals. The plants were cultivated for about 60 days in different concentrations of Cd, Ni, Pb and Zn (tested alone) in controlled environmental conditions and availability of nutrients. The results indicated that S. minima was able to grow in low concentrations of selected metals (0.03 mg L^?1 Cd, 0.40 mg L^?1 Ni, 1.00 mg L^?1 Pb and 1.00 mg L^?1 Zn) and still able to adsorb or accumulate metals in their tissues when cultivated in higher concentrations of selected metals without necessarily grow. The maximum values of removal metal rates (mg m² day^?1) for each metal (Cd = 0.0045, Ni = 0.0595, Pb = 0.1423 e Zn = 0.4046) are listed. We concluded that S. minima may be used as an additional tool for metals removal from effluent.     

A Study on Cadmium Phytoremediation Potential of Indian Mustard,Brassica juncea

The objective of this study was to investigate Cd phytoremediation ability of Indian mustard, Brassica juncea. The study was conducted with 25, 50, 100, 200 and 400 mg Kg^?1 CdCl₂ in laboratory for 21 days and Cd concentrations in the root, shoot and leaf tissues were estimated by atomic absorption spectroscopy. The plant showed high Cd tolerance of up to 400 mg Kg^?1 but there was a general trend of decline in the root and shoot length, tissue biomass, leaf chlorophyll and carotenoid contents. The tolerance index (TI) of plants were calculated taking both root and shoot lengths as variables. The maximum tolerance (TI _shoot = 87.4 % and TI _root = 89.6 %) to Cd toxicity was observed at 25 mg Kg^?1, which progressively decreased with increase in dose. The highest shoot (10791 μg g^?1 dry wt) and root (9602 μg g^?1 dry wt) Cd accumulation was achieved at 200 mg kg^?1 Cd treatment and the maximum leaf Cd accumulation was 10071.6 μg g^?1 dry wt achieved at 100 mg Kg^?1 Cd, after 21 days of treatment. The enrichment coefficient and root to shoot translocation factor were calculated, which, pointed towards the suitability of Indian mustard for removing Cd from soil.     

Concentration,Distribution, Source,and Risk Assessment of PAHs and Heavy Metals in Surface Water from the Three Gorges Reservoir,China

Fifteen polycyclic aromatic hydrocarbons (PAHs) and heavy metals (Cr, Ni, As, Cd, Pb, and Hg) were quantified in 19 surface water sites of the Three Gorges Reservoir, China. The total concentrations of 15 PAHs and six heavy metals in the 19 sample sites ranged from 130.8 ng L^?1 to 227.5 ng L^?1 and 3.2 μg L^?1 to 6.0 μg L^?1, respectively. The mean concentration of As was the highest among the six heavy metals (2.1 ± 0.3 μg L^?1), followed by Cr (0.5 ± 0.3 μg L^?1), Ni (1.3 ± 0.1 μg L^?1), Cd (0.2 ± 0.01 μg L^?1), Pb (0.07 ± 0.08 μ g L^?1) and Hg (0.05 ± 0.08 μg L^?1). The isomer ratio results suggest that PAHs at most sites were mainly from petroleum combustion, while coal and biomass combustion was the main source at sites 1, 2, 6, 7, 9, 14, and 17. Based on principal component analysis, the main source of heavy metals was anthropogenic activities and weathering of bedrocks. Depending on characteristic of RQ_(NCs) ≥ 1 and RQ_(MPCs) < 1, BaA showed higher potential ecological risk than other PAHs, therefore, all sampling site needed to be paid much more attention, included some remedial actions. Meanwhile, after assessing human health risk of heavy metal, it was unlikely to experience adverse health effects, even exposing through more pathways and six kinds of heavy metals simultaneously.     

An Abandoned Copper Mining Site in Cyprus and Assessment of Metal Concentrations in Plants and Soil

Mining is an important source of metal pollution in the environment and abandoned mines are extremely restricted habitats for plants. Some plant species growing on metalliferous soils around mine tailings and spoil-heaps are metal-tolerant and accumulate high concentrations of metals. In this investigation, we aimed to perform a research in the CMC-abandoned copper mining area in Lefke-North Cyprus to assess the recent metal pollution in soil and plant systems. We collected 16 soil samples and 25 plant species from 8 localities around the vicinity of tailing ponds. Some concentrations of metals in soil samples varied from 185 to 1023 mg kg^?1 Cu, 15.2 to 59.2 mg kg^?1 Ni, 2.3 to 73.6 mg kg^?1 Cd and metals for plants ranged from 0.135 to 283 mg kg^?1 Cu, 0.26 to 31.2 mg kg^?1 Ni, 0.143 to 277 mg kg^?1 Cd. Atriplex semibaccata, Acacia cyanophylla, Erodium spp., Inula viscosa, Juncus sp., Oxalis pes-caprea, Pistacia lentiscus, Senecio vulgaris and Tragopogon sinuatus accumulated higher concentrations. BCF for Atriplex semibaccata was found very high, for this reason this plant can tentatively be considered as a hyperaccumulator of Cu and Cd, but it needs further investigation for its potential in phytoremediation.     

Phytoremediation of Landfill Leachate with Colocasia esculenta,Gynerum sagittatum and Heliconia psittacorum in Constructed Wetlands

This study assessed the accumulation of Cd (II), Hg (II), Cr (VI) and Pb (II) in Gynerium sagittatum (Gs), Colocasia esculenta (Ce) and Heliconia psittacorum (He) planted in constructed wetlands treating synthetic landfill leachate. Sixteen bioreactors were operated in two experimental blocks. Metal concentrations in the influent and effluent; root, stem, branch and leaves of plants were analysed, as well as COD, N-NH₄⁺, TKN, T, pH, ORP, DO, and EC. Average removal efficiencies of COD, TKN and NH₄⁺-N were 66, 67 and 72%, respectively and heavy metal removal ranged from 92 to 98% in all units. Cr (VI) was not detected in any effluent sample. The bioconcentration factors (BCF) were 10⁰ -10². The BCF of Cr (VI) was the lowest: 0.59 and 2.5 (L kg^?1) for Gs and He respectively; whilst Cd (II) had the highest (130–135 L kg^?1) for Gs. Roots showed a higher metal content than shoots. Translocation factors (TF) were lower, He was the plant exhibiting TFs >1 for Pb (II), Cr (T) and Hg (II) and 0.4–0.9 for Cd (II) and Cr (VI). The evaluated plants demonstrate their suitability for phytoremediation of landfill leachate and all of them can be categorized as metals accumulators.     

Decontamination of coal mine effluent generated at the Rajrappa coal mine using phytoremediation technology

Toxicity of the effluent generated at the Rajrappa coal mine complex under the Central Coalfields Limited (CCL, a subsidiary of Coal India Limited) in Jharkhand, India was investigated. The concentrations (mg L^?1) of all the toxic metals (Fe, Mn, Ni, Zn, Cu, Pb, Cr, and Cd) in the coal mine effluent were above the safe limit suggested by the Environmental Protection Agency (EPA 2003). Among these, Fe showed the highest concentration (18.21 ± 3.865), while Cr had the lowest effluent concentration (0.15 ± 0.014). Efforts were also made to detoxify the effluent using two species of aquatic macrophytes namely “‘Salvinia molesta and Pistia stratiotes.” After 10 days of phytoremediation, S. molesta removed Pb (96.96%) > Ni (97.01%) > Cu (96.77%) > Zn (96.38%) > Mn (96.22%) > Fe (94.12%) > Cr (92.85%) > Cd (80.99%), and P. stratiotes removed Pb (96.21%) > Fe (94.34%) > Ni (92.53%) > Mn (85.24%) > Zn (79.51%) > Cr (78.57%) > Cu (74.19%) > Cd (72.72%). The impact of coal mine exposure on chlorophyll content showed a significant decrease of 42.49% and 24.54% from control values in S. molesta and P. stratiotes, respectively, perhaps due to the damage inflicted by the toxic metals, leading to the decay of plant tissues.     

Application of Heavy Metal Rich Tannery Sludge on Sustainable Growth,Yield and Metal Accumulation by Clarysage (Salvia sclarea L.)

A field experiment was conducted to evaluate the effective utilization of tannery sludge for cultivation of clarysage (Salvia sclarea) at CIMAP research farm, Lucknow, India during the year 2012–2013. Six doses (0, 20, 40, 60, 80, 100 tha^?1) of processed tannery sludge were tested in randomised block design with four replications. Results revealed that maximum shoot, root, dry matter and oil yield were obtained with application of 80 tha^?1of tannery sludge and these were 94, 113 and 61% higher respectively, over control. Accumulation of heavy metals (Cr, Ni, Fe, Pb) were relatively high in shoot portion of the plant than root. Among heavy metals, magnitude of chromium accumulation was higher than nickel, iron and lead in shoot as well as in root. Linalool, linalyl acetate and sclareol content in oil increased by 13,8 and 27% respectively over control, with tannery sludge application at 80 tha^?1. Heavy metals such as chromium, cadmium and lead content reduced in postharvest soil when compared to initial status. Results indicated that clarysage (Salvia sclarea) can be grown in soil amended with 80 tha^?1sludge and this can be a suitable accumulator of heavy metals for phytoremediation of metal polluted soils.     

Melatonin affects the growth and cadmium accumulation of Malachium aquaticum and Galinsoga parviflora

Phytoremediation technology has become one of the main techniques for remediating soils polluted by heavy metals because it does not damage the environment, but heavy metal-tolerant plants have the disadvantages of low biomass and slow growth. A pot experiment was conducted to study the effects of melatonin (Mel) on growth and cadmium (Cd) accumulation in the Cd accumulator Malachium aquaticum and hyperaccumulator Galinsoga parviflora by spraying different concentrations of Mel on them. The results showed that shoot biomass, photosynthetic pigment content and antioxidant enzyme activity were increased in both species after Mel was sprayed on their leaves. Mel reduced the Cd content in shoots of M. aquaticum and increased it in those of G. parviflora. In general, Cd accumulation was greatest in M. aquaticum when Mel was 200 μmol L^?1 (120.71 μg plant^?1, increased by 15.97% than control) and in G. parviflora when Mel was 100 μmol L^?1 (132.40 μg plant^?1, increased by 68.30% than control). Our results suggest it is feasible to improve the remediation efficiency of lightly Cd-contaminated soil by spraying G. parviflora with100 μmol L^?1 Mel.     

Phytoremediation of Wastewater with Limnocharis Flava,Thalia Geniculata and Typha Latifolia in Constructed Wetlands

Phytoremediation is thought to be the most sustainable wastewater treatment option for developing countries. However, its application is often limited by unavailability of suitable candidate species. In the present study, the potentials of Limnocharis flava, Thalia geniculata and Typha latifolia for remediation of heavy metal contaminated wastewater with a constructed wetland system were evaluated. The wetland consisted of three treatment lines each planted with sufficient and equal number of a species. Duplicate plant and water samples were collected bi-monthly and analyzed for Fe, Cu, Zn, Pb, and Hg using the atomic absorption spectrophotometer over a six month period. Bioaccumulation rates generally increased over time and varied among plants for these metals, with Fe (456–1549 mg kg¹ roots; 20–183 mg kg^?1 shoot) being the most sequestered and Pb (1.2–7.6 mg kg^?1 roots; 1.55–3.95 mg kg^?1 shoot) the least. Translocation factors differed among the species but generally remained stable over time. L. flava showed potential for hyperaccumulating Hg. Removal efficiencies varied for the studied metals (～ 20–77 %) and were generally related to metal uptake by the plants. These results demonstrate the suitability of the species for phytoremediation, and the usefulness of the technique as an option for improving irrigation water quality in Ghana.

Supplemental materials are available for this article. Go to the publisher's online edition of International Journal of Phytoremediation to view the supplemental file.     

Uptake and Bioaccumulation of Pentachlorophenol by Emergent Wetland Plant Phragmites australis (Common Reed) in Cadmium Co-contaminated Soil

Despite many studies on phytoremediation of soils contaminated with either heavy metals or organics, little information is available on the effectiveness of phytoremediation of co-occurring metal and organic pollutants especially by using wetland species. Phragmites australis is a common wetland plant and its potential for phytoremediation of cadmium pentachlorophenol (Cd-PCP) co-contaminated soil was investigated. A greenhouse study was executed to elucidate the effects of Cd (0, 10, and 20 mg kg^?1) without or with PCP (0, 50, and 250 mg kg^?1) on the growth of the wetland plant P. australis and its uptake, accumulation and removal of pollutant from soils. After 75 days, plant biomass was significantly influenced by interaction of Cd and PCP and the effect of Cd on plant growth being stronger than that of PCP. Coexistence of PCP at low level lessened Cd toxicity to plants, resulting in improved plant growth and increased Cd accumulation in plant tissues. The dissipation of PCP in soils was significantly influenced by interactions of Cd, PCP and plant presence or absence. As an evaluation of soil biological activities after remediation soil enzyme was measured.     

Mycorrhizal symbiosis and phosphorus fertilization effects on Zea mays growth and heavy metals uptake

Arbuscular mycorrhizal fungi (AMF) can promote plant growth and reduce plant uptake of heavy metals. Phosphorus (P) fertilization can affect this relationship. We investigated maize (Zea mays L.) uptake of heavy metals after soil AMF inoculation and P fertilization. Maize biomass, glomaline and chlorophyll contents and uptake of Fe, Mn, Zn, Cu, Cd and Pb have been determined in a soil inoculated with AMF (Glomus aggregatum, or Glomus intraradices) and treated with 30 or 60 µg P-K₂HPO₄ g^?1 soil. Consistent variations were found between the two mycorrhizal species with respect to the colonization and glomalin content. Shoot dry weight and chlorophyll content were higher with G. intraradices than with G. aggregatum inoculation. The biomass was highest with 30 µg P g^?1 soil. Shoot concentrations of Cd, Pb and Zn decreased with G. aggregatum inoculation, but that of Cd and Pb increased with G. intraradices inoculation. Addition of P fertilizers decreased Cd and Zn concentrations in the shoot. AMF with P fertilization greatly reduced maize content of heavy metals. The results provide that native AMF with a moderate application rate of P fertilizers can be exploited in polluted soils to minimize the heavy metals uptake and to increase maize growth.     

Phytofiltration of As3+, As5+, and Hg by the aquatic macrophyte Potamogeton pusillus L,and its potential use in the treatment of wastewater

The aim of this paper was to investigate the capacity of the aquatic macrophyte Potamogeton pusillus to remove As³⁺, As⁵⁺, and Hg from aqueous solutions. The plants were exposed to 0 mg.L^?1, 0.1 mg.L^?1, 0.5 mg.L^?1, 1 mg.L^?1, or 2 mg.L^?1 of As³⁺, As⁵⁺, and Hg for 20 days. The results obtained for the individual removal of As³⁺, As⁵⁺, and Hg from water solutions, together with their accumulation in P. pusillus, indicate that this plant can be effectively used for the removal of Hg and of moderate concentrations of As³⁺ or As⁵⁺ (0.1 mg.L^?1) from aquatic systems. Roots and leaves accumulated the highest amount of As when the plant was exposed to As⁵⁺, but when it was exposed to As³⁺, the root accumulated the highest amount of As, and the leaves, the highest amount of Hg. When compared to other aquatic plants species, the results showed that P. pusillus demonstrated a higher Hg accumulation (2465 ± 293 µg.g^?1) when the transfer coefficient was 40,580 ± 3762 L.kg ^?1, showing the great potential of this macrophyte for phytoremediation of water contaminated with Hg. To the extent of our knowledge, this is the first report on bioaccumulation of As³⁺, As⁵⁺, and Hg by P. pusillus.     

Effect of bacterial inoculation of strains of pseudomonas aeruginosa,alcaligenes feacalis and bacillus subtilis on germination,growth and heavy metal (cd,cr, and ni) uptake of brassica juncea

Bacterial inoculation may influence Brassica juncea growth and heavy metal (Ni, Cr, and Cd) accumulation. Three metal tolerant bacterial isolates (BCr3, BCd33, and BNi11) recovered from mine tailings, identified as Pseudomonas aeruginosa KP717554, Alcaligenes feacalis KP717561, and Bacillus subtilis KP717559 were used. The isolates exhibited multiple plant growth beneficial characteristics including the production of indole-3-acetic acid, hydrogen cyanide, ammonia, insoluble phosphate solubilization together with the potential to protect plants against fungal pathogens. Bacterial inoculation improved seeds germination of B. juncea plant in the presence of 0.1 mM Cr, Cd, and Ni, as compared to the control treatment. Compared with control treatment, soil inoculation with bacterial isolates significantly increased the amount of soluble heavy metals in soil by 51% (Cr), 50% (Cd), and 44% (Ni) respectively. Pot experiment of B. juncea grown in soil spiked with 100 mg kg^?1 of NiCl₂, 100 mg kg^?1 of CdCl₂, and 150 mg kg^?1 of K₂Cr₂O₇, revealed that inoculation with metal tolerant bacteria not only protected plants against the toxic effects of heavy metals, but also increased growth and metal accumulation of plants significantly. These findings suggest that such metal tolerant, plant growth promoting bacteria are valuable tools which could be used to develop bio-inoculants for enhancing the efficiency of phytoextraction.     

Comparison of heavy metal phytoremediation in monoculture and intercropping systems of Phyllostachys praecox and Sedum plumbizincicola in polluted soil

A bamboo species (Phyllostachys praecox) and a Cd/Zn hyperaccumulator (Sedum plumbizincicola) were tested under different planting systems to compare their heavy metal phytoremediation ability. P. praecox (MP), S. plumbizincicola (MS) and P. praecox × S. plumbizincicola (IPS) plantations were established in Cu, Zn, and Cd-contaminated soil. Soil properties and heavy metal contents in plants were determined and compared after four years of plantation establishment. The rankings of available and total metal contents in soil layers were MP > MS > IPS (0–20 cm) and MP > IPS > MS (20–40 cm, except for Cu), respectively. The Cu and Zn contents in mature bamboo tissues were significantly lower, but the Cd contents in bamboo tissues (except for leaves) higher, in the IPS than in the MP. The bioconcentration and the translocation factors in most of bamboo tissues showed an increasing trend from the MP to the IPS. Heavy metal distribution in plants is greatly affected by the planting patterns. The tested intercropping system of two plant species showed higher biomass productivity, implying more heavy metals can be removed from the soil through the harvesting of plants. Therefore, the IPS leads to significant improvement of soil phytoremediation.     

Phytoextraction of heavy metals by Sesuvium portulacastrum l. a salt marsh halophyte from tannery effluent

The present study investigated the sources for remediation of heavy metals and salts from tannery effluent using salt marsh halophyte Sesuvium portulacastrum. From the results observed, in tannery effluent treated soil from 1 kg dry weight of plant sample, Sesuvium portulacastrum accumulated 49.82 mg Cr, 22.10 mg Cd, 35.10 mg Cu and 70.10 mg Zn and from 1 g dry weight of the plant sample, 246.21 mg Na Cl. Cultivation of Sesuvium portulacastrum significantly reduced the EC, pH and SAR levels in tannery effluent and salt treated soil and correspondingly increased in plant sample after 125 days of cultivation. In conclusion, Sesuvium portulacastrum was an efficient in accumulating heavy metals such as Chromium, Cadmium, Copper and Zinc, sodium and chloride maximum through its leaves when compared to stem and root. The finding of these bioacccumulation studies indicates that Sesuvium portulacastrum could be used for phytoremediation of tannery effluent contaminated field.     

Evaluation of Atriplex Halimus,Medicago Lupulina and Portulaca Oleracea For Phytoremediation of Ni,Pb, and Zn

Suitable plant species are able to accumulate heavy metals and to produce biomass useful for non-food purposes. In this study, three endemic Mediterranean plant species, Atriplex halimus, Portulaca oleracea and Medicago lupulina were grown hydroponically to assess their potential use in phytoremediation and biomass production. The experiment was carried out in a growth chamber using half strength Hoagland's solutions separately spiked with 5 concentrations of Pb and Zn (5, 10, 25, 50, and 100 mg L^?1), and 3 concentrations of Ni (1, 2 and 5 mg L^?1). Shoot and root biomass were determined and analyzed for their metals contents. A. halimus and M. lupulina gave high shoot biomass with relatively low metal translocation to the above ground parts. Metals uptake was a function of both metals and plant species. It is worth noting that M. lupulina was the only tested plant able to grow in treatment Pb50 and to accumulate significant amount of metal in roots. Plant metal uptake efficiency ranked as follows: A. halimus > M. lupulina > P. oleracea . Due to its high biomass production and the relatively high roots metal contents, A. halimus and M. lupulina could be successfully used in phytoremediation, and in phytostabilization, in particular.     

Phytoremediation potential of some halophytic species for soil salinity

Phytoremediation potential of six halophytic species i.e. Suaeda nudiflora, Suaeda fruticosa, Portulaca oleracea, Atriplex lentiformis, Parkinsonia aculeata and Xanthium strumarium was assessed under screen house conditions. Plants were raised at 8.0, 12.0, 16.0, and 20.0 dSm^?1 of chloride-dominated salinity. The control plants were irrigated with canal water. Sampling was done at vegetative stage (60–75 DAS). About 95 percent seed germination occurred up to 12 dSm^?1 and thereafter declined slightly. Mean plant height and dry weight plant^?1 were significantly decreased from 48.71 to 32.44 cm and from 1.73 to 0.61g plant^?1 respectively upon salinization. Na⁺/K⁺ ratio (0.87 to 2.72), Na⁺/ Ca²⁺ + Mg²⁺ (0.48 to 1.54) and Cl^?/SO₄^2– (0.94 to 5.04) ratio showed increasing trend. Salinity susceptibility index was found minimum in Suaeda fruticosa (0.72) and maximum in Parkinsonia aculeata (1.17). Total ionic content also declined and magnitude of decline varied from 8.51 to 18.91% at 8 dSm^?1 and 1.85 to 7.12% at 20 dSm^?1 of salinity. On the basis of phytoremediation potential Suaeda fruticosa (1170.02 mg plant^?1), Atriplex lentiformis (777.87 mg plant^?1) were the best salt hyperaccumulator plants whereas Xanthium strumarium (349.61 mg plant^?1) and Parkinsonia aculeata (310.59 mg plant^?1) were the least hyperaccumulator plants.     

Effects of Arsenic on Growth, Photosynthetic Activity, and Accumulation in Two New Hyperaccumulating Populations of Isatis cappadocica Desv.

The effect of arsenic on leaf photosynthetic rate, growth responses, and accumulation capability of Isatis cappadocica Desv., a Brassica collected from Iranian arsenic-contaminated mine spoils and control populations, was investigated. Both populations of I. cappadocica were considerably more tolerant than the reference Brassica species (Descurainia sophia). The 1,000 μM arsenate exposure inhibited root growth completely in D. sophia, but only by 50 and 40 % in the nonmine and mine populations of I. cappadocica, respectively. Furthermore, the chlorophyll contents of both populations of I. cappadocica were not statistically different, especially when plants were exposed to 5–800 μM As. The chlorophyll a fluorescence kinetics (F _v/F _m) and electron transfer rate values of treated I. cappadocica populations remained unaffected, indicating normal photosynthetic efficiency and strength of plants in the presence of arsenic. After 28 days of exposure to 1,300 μM As, shoot arsenic concentrations of mine and nonmine populations reached 310 and 345 mg kg^?1, respectively, with the arsenic transfer factor and bioaccumulation greater than 1.0. According to these results, it was shown that I. cappadocica had strong tolerance to and the capability to hyperaccumulate arsenic; therefore, it is a potential As hyperaccumulator.     

Enhancing Phytoremediation Potential of Pennisetum clandestinum Hochst in Cadmium-Contaminated Soil Using Smoke-Water and Smoke-Isolated Karrikinolide

The use of plant growth regulators (PGRs) and biostimulants to enhance phytoextraction is gaining popularity in phytoremediation technology. This study investigated the stimulatory effects of smoke-water (SW), a smoke-derived compound karrikinolide (KAR₁) and other known plant growth regulators (PGRs) [gibberellic acid (GA₃), kinetin (Kin) and indole-3-butyric acid (IBA)] to enhance the phytoextraction potential of Pennisetum clandestinum. Pennisetum clandestinum seedlings were grown for 10 weeks in vermiculite using Hoagland's nutrient solution and were treated with cadmium (Cd) (2, 5, and 10 mg L^?1) and SW, KAR₁ and PGRs. KAR₁ exhibited positive effects on shoot and root dry weight (140 and 137 mg respectively) at the highest concentration of Cd (10 mg L^?1) compared to all the other treatments. KAR₁ and SW treatments used in the present study significantly improved the phytoextraction potential of P. clandestinum (602 and 575 mg kg^?1 respectively) compared to the other tested PGRs. This is the first report on the use of SW and KAR₁ to enhance phytoremediation potential in P. clandestinum. Further studies are needed to elucidate the exact mechanisms of smoke constituents involved in phytoextraction potential of plant species.