International Journal of Phytoremediation最新文献

The use of woody species for the remediation of heavy metal-contaminated soils is an environmentally friendly and economically viable strategy. This study investigates the phytoextraction abilities of 15 woody species for copper, lead and zinc in contaminated soil. The results indicated that all species showed phytoextraction ability, with metal concentrations varying from 5.59 to 27.45 mg·kg^-1 for Cu, 2.79 to 16.75 mg·kg^-1 for Pb and 22.13 to 185.72 mg·kg^-1 for Zn in the stem tissues depending on the species. Pterocarya stenoptera, Paulownia fortunei and Salix matsudana were identified as the top performers in terms of overall phytoextraction capacity. Notably, their capacity to transport zinc exceeded that of copper and lead. The enrichment of copper, lead and zinc in the soil showed a synergistic effect in the presence of heavy metal. The distribution of heavy metals within plant tissues was affected by water content and the inherent toxicity of metals. The study highlights that the accumulation of tree biomass and water content in the stem play a significant role in determining the amount of heavy metals phytoextracted. This insight offers a quick method for the rapid selection of woody species for phytoremediation in urban soils contaminated with heavy metals.

Plants face numerous environmental challenges from biotic and abiotic stressors, with soil salinization emerging as a significant global concern. The coastal regions of Tamil Nadu, face severe environmental challenges due to discharge of saline water from shrimp farms exacerbates this issue, compromising the viability of paddy and other crops in the vicinity. This study explores the phytoremediation potential of Suaeda fruticosa in addressing soil salinity resulting from shrimp farming activities under field conditions over a 120-day period to restore soil health in salt affected soil. This research demonstrates Suaeda fruticosa's exceptional salt tolerance and bioaccumulation potential in facilitating soil restoration. Significant enhancements were observed in various growth parameters, including 466% increase in plant height, 338% in fresh weight and 387% in dry weight. Biochemical parameters also showed substantial enhancements with total chlorophyll, protein, proline, phenol, and glycinebetaine levels increasing by 655%, 588%, 690%, 153%, and 531%, respectively. Enzymatic activities exhibited notable elevations as well, with catalase, peroxidase, and polyphenol oxidase activities escalating by 258%, 587%, and 121% respectively, indicating robust adaptation to saline environments. Moreover, Suaeda fruticosa exhibited remarkable bioaccumulation capabilities, accumulating 461 kg NaCl ha^-1. This led to substantial improvements in soil characteristics, including a reduction in pH from 8.8 to 6.49, electrical conductivity from 5.7 to 1.53 dSm^-1, and sodium adsorption ratio from 16.1 to 4.4 mmol L^-1. The successive cultivation of Suaeda fruticosa in this study, has proven to be a viable strategy for reclaiming salt-affected lands, thereby alleviating a significant constraint on crop productivity.

A hydroponic experiment was conducted to investigate the variations in membrane permeabilities, chlorophyll contents, antioxidase activities, the ascorbic acid (AsA)-glutathione (GSH) cycle, and the glyoxalase system in the leaves of Pontederia cordata with 0 ∼ 15.0 mg L^-1 lead ion (Pb²⁺) exposure. The concentrations of Pb²⁺ accumulated in the plant roots, stems, and leaves were also evaluated. After 7 days of exposure, the plants maintained normal growth, and there was a significant increase in ascorbate peroxidase and dehydroascorbate reductase activities. With 5.0 mg L^-1 Pb²⁺ exposure for 28 days, nearly 66.36% of Pb²⁺ accumulated in the roots, while excess Pb²⁺ immobilized in the leaves was not observed. Exposure to 10.0 and 15.0 mg L^-1 Pb²⁺ for 28 days significantly increased Pb²⁺ contents in the leaves. This led to decrease in chlorophyll a, b, and carotenoid contents, and to increase in the methylglyoxal content in the leaves. With 10 and 15 mg L^-1 Pb²⁺ exposure, NPT and PCs contents in leaves increased. however, the glyoxalase system did not function well in the plant tolerant to Pb²⁺ at higher concentrations. The AsA-GSH cycle did not cooperate with the glyoxalase system in the plant defense against Pb²⁺ exposure in the present investigation.

Phytoremediation of manganese (Mn)-contaminated water requires the selection of Mn-tolerant species. This study reports on physiological changes and Mn bioaccumulation in the aquatic macrophyte Pistia stratiotes cultivated under various MnCl₂ concentrations: control, 80, 340, 600, 1000, 2000, and 4000 µM. Few visual symptoms of Mn toxicity, such as chlorosis, were observed after 10 days, especially in plants treated with 2000 and 4000 µM MnCl₂. High Mn accumulation was recorded, with maximum values of 23,700 and 24,600 µg g^-1 DW in the shoots and roots, respectively, at 4000 µM Mn, contrasting with 825.01 and 1587.53 µg g^-1 DW in control plants. Cellular fractioning showed that Mn in shoots and roots was mainly associated with the cell wall, with approximately 90% of the Mn in roots detected in the apoplast. There were no significant changes in net CO₂ assimilation or respiratory rates after 5 and 10 days of Mn exposure. These results demonstrate that P. stratiotes is a Mn hyperaccumulator species with excellent phytoremediation potential, as shown by its high bioaccumulation capacity and its ability to maintain photosynthetic efficiency under Mn stress.

Heavy metals and petroleum oil are the two most important contaminants in the environment. Currently, phytoremediation is regarded as an effective and affordable solution that allows the attenuation of toxic pollutants through the use of plants. Not many studies are carried out regarding the use of aromatic plants capable of remediating soil that is co-contaminated by heavy metal and petroleum hydrocarbons. A pot experiment was conducted to investigate the influence of cadmium-resistant PGPR Micrococcus luteus on the phytoremediation efficiency of Ocimum gratissimum in Cd and petroleum co-contaminated soil. The plants were harvested after 60 days of treatment and their growth and biomass were determined. The accumulation of Cd in plant shoots and roots was determined. The residual petroleum hydrocarbon concentration during the 60 days of the phytoremediation experiment was determined using GC-FID. O. gratissimum with M. luteus showed the highest Cd accumulation (14.05 mg kg^-1) and the highest reduction of TPH (46.64%). M. luteus ameliorated contaminant toxicity and promoted biomass production of O. gratissimum. These results demonstrated that O. gratissimum in combination with M. luteus can be efficiently used to remediate Cd and petroleum-co-contaminated soils.

This review addresses plant interactions with HMs, emphasizing defence mechanisms and the role of chelating agents, antioxidants and various elicitor molecules in mitigating metal toxicity in plants. To combat soil contamination with HMs, chelate assisted phytoextraction using application of natural or synthetic aminopolycarboxylic acids is an effective strategy. Plants also employ diverse signaling pathways, including hormones, calcium, reactive oxygen species, nitric oxide, and Mitogen-Activated Protein Kinases influencing gene expression and defence mechanisms to counter HM stress. Phytohormones enhance the enzymatic and non-enzymatic antioxidant defence mechanism and the level of secondary metabolites in plants when exposed to HM stress. Also it activates genes responsible for DNA repair mechanism. In addition, the plant hormones can also regulate the activity of several transporters of HMs, thereby preventing their entry into the cell. Elicitor molecules regulate metal and metalloid absorption, sequestration and transport in plants. Combining of different elicitors like jasmonic acid, calcium, salicylic acid etc. effectively mitigates metal and metalloid stress in plants. Moreover, microbes including bacteria and fungi, offer eco-friendly and efficient solution for HM remediation. Understanding these elicitors, microbes and various signaling pathways is crucial for developing strategies to enhance plant resilience to metal and metalloid stress.

Electrolytic manganese slag (EMR) is a solid waste generated in the manganese hydrometallurgy process. It not only takes up significant land space but also contains Mn²⁺, which can lead to environmental contamination. There is a need for research on the treatment and utilization of EMR. Improved EMR substrate for Pennisetum sinese Roxb growth was determined in pot planting experiments. The study tested the effects of leaching solution, microorganisms, leaf cell structures, and growth data. Results indicated a substrate of 45% EMR, 40% phosphogypsum, 5% Hericium erinaceus fungi residue, 5% quicklime, and 5% dolomite sand significantly increased the available phosphorus content (135.54 ± 2.88 μg·g^-1) by 17.95 times, compared to pure soil, and enhanced the relative abundance of dominant bacteria. After 240 days, the plant height (147.00 ± 0.52 cm), number of tillers (6), and aerial dry weight (144.00 ± 15.99g) of Pennisetum sinese Roxb increased by 5.81%, 200%, and 32.58%, respectively. Analyses of leaves and leaching solution revealed that the highest leaf Mn content (46.84 ± 2.91 μg·g^-1) being 3.38 times higher than in pure soil, and the leaching solution Mn content (0.66 ± 0.13 μg·g^-1) was lowest. Our study suggested P. sinese Roxb grown in an improved EMR substrate could be a feasible option for solidification treatment and resource utilization of EMR.

While phytoremediation has been widely employed for greywater treatment, this system suffers from the transfer of considerable amounts of surfactants to the aquatic environment through partially treated effluent and/or exhausted plant disposal. Hence, this study focuses on greywater phytoremediation followed by recycling the spent plant for preparing an adsorbent material used as post-treatment. P. crassipes was used to operate a phytoremediation unit under 23 °C, 60% relative humidity, plant density (5-30 g/L), dilution (0-50%), pH (4-10), and retention time (3-15 days). The optimum condition was 12.7 g/L density, 34.0% dilution, pH 8.4, and 13 days, giving chemical oxygen demand (COD), surfactant, and NH₄-N removal efficiencies of 94.62%, 90.45%, and 88.09%, respectively. The exhausted plant was then thermally treated at 550 °C and 40 min to obtain biochar used as adsorbent to treat the phytoremediation effluent. The optimum adsorption process was biochar dosage of 1.51 g/L, pH of 2.1, and 137 min, providing a surfactant removal efficiency of 92.56%. The final discharge of this phytoremediation/adsorption combined process contained 8.30 mg/L COD, 0.23 mg/L surfactant, and 0.94 mg/L NH₄⁺-N. Interestingly, this approach could be economically feasible with a payback period of 6.5 years, 14 USD net present value, and 8.6% internal rate of return.

Partially Saturated Vertical Constructed Wetlands (PSV-CWs) are novel wastewater treatment systems that work through aerobic and anaerobic conditions that favor the removal of pollutants found in high concentrations, such as rivers contaminated with domestic wastewater and landfill leachate. The objective of the study was to evaluate the efficiency of PSV-CWs using monocultures and polycultures of Typha latifolia and Heliconia psittacorum to treat river waters contaminated with leachates from open dumps and domestic wastewater. Six experimental units of PSV-CWs were used; two were planted with Typha latifolia monoculture, two with Heliconia psittacorum monoculture and two with polycultures of both plants. The results indicated better organic matter and nitrogen removal efficiencies (p < 0.05) in systems with polycultures (TSS:95%, BOD₅:83%, COD:89%, TN:82% and NH₄₊:99%). In general, the whole system showed high average removal efficiencies (TSS:93%, BOD₅:79%, COD:85%, TN:79%, NH₄₊:98% and TP:85%). Regarding vegetation, both species developed better in units with monocultures, being Typha latifolia the one that reached a more remarkable development. However, both species showed high resistance to the contaminated environment. These results showed higher removals than those reported in the literature with conventional Free Flow Vertical Constructed Wetlands (FFV-CWs), so PSV-CWs could be a suitable option to treat this type of effluent.

This study aimed to examine the potential of soil amendment-assisted phytoremediation using ryegrass in reclaiming abandoned gold mine soil in southwestern Ghana, with a specific focus on the soil contamination hazards associated with metals and metalloids. A pot experiment lasting 60 days was carried out to assess the efficacy of soil amendments, such as compost, iron oxide, and poultry manure, in mitigating environmental hazards. Three soil contamination indices (soil contamination = CF, enrichment factor = ER, and pollution load index = PLI) were used to calculate the extent of soil contamination, enrichment, and pollution of the sites with Co, Hg, Ni, Mo, Se, Sb, and Pb. The findings show that Hg made the greatest contribution (with a maximum soil CF of 18.0) to the overall PLI, with a maximum value of 74.4. The sites were averagely and consequently enriched with toxic elements in the decreasing order: Ni (ER = 33.3) > Mo (20.5) > Sb (14.1) > Pb (11.0) > Hg (7.9) > Se (2.1). The bioaccumulation factor (BCF > 1) suggests that ryegrass has the ability to phytostabilize Co, Hg, Mo, and Ni. This means that the plant may store these elements in its roots, potentially decreasing their negative effects on the environment and human health. Ultimately, the addition of combined manure with iron oxides might have augmented the sequestration of these metals in the root. The elements may have accumulated through sorption on manure or Fe surfaces, dissolution from watering the plants in the pot, or mineralization of organic manure. Thus, ryegrass has shown potential for phytostabilisation of Co, Hg, Mo, and Ni when assisted with a combination of manure and iron oxides; and can consequently mitigate the environmental and human health impacts.