International Journal of Phytoremediation最新文献

This research focused on applying three microalgae Chlorella vulgaris, Chlorella sorokiniana, and local strain Haematococcus pluvialis for wastewater remediation at high temperature, assessing their efficiency in reducing nitrogen (NH₄⁺ and NO₃^-), phosphorus (PO₄^-3) and soluble chemical oxygen demand (COD). The growth rates, proximate and fatty acid (FA) compositions of microalgae were also investigated. Initially, microalgae were cultured in BG-11 medium in 250-mL Erlenmeyer's for 10 days, then scaled up to 1-L Erlenmeyer's for another 10 days, and finally to 5-L plastic vessels for another 15 days. For wastewater treatment (WWT), microalgae were cultivated in rectangular, bench-scale plastic containers (15 L) for 14 days at 35 °C. Growth performance did not change for the first 10 days; however, C. vulgaris and H. pluvialis showed significantly higher growth, compared to C. sorokiniana at the end of the experiment in BG-11 medium. Regarding WWT, C. vulgaris and H. pluvialis showed significantly higher growth performance than C. sorokiniana at the end of the14-day experiment. H. pluvialis showed the highest PO₄^-3 removal rate (96.53%). However, no significant difference was observed in NH₄⁺ removal, which was over 90% for all species. On the other hand, C. vulgaris and H. pluvialis showed significantly higher removal for NO₃^- (92.07% and 92.17%) and for COD (88.44 and 87.55%), respectively, compared to C. sorokiniana. Regarding FA composition of microalgae before WWT, C. sorokiniana and H. pluvialis were dominated by saturated fatty acids (SFA) (39.4 and 50.1%, respectively), while monounsaturated fatty acids (MUFA) were the most abundant ones in C. vulgaris (35.1%). After WWT, SFAs significantly increased in C. vulgaris (95.5%-increment) while they were significantly decreased (17.9%-decrement) in H. pluvialis, and did not change in C. sorokiniana. The findings suggest that all strains, specially C. vulgaris and H. pluvialis, have remarkable capabilities for nutrient absorption at high temperatures, which makes these strains suitable for arid regions.

Phytoremediation is an emerging technology that is claimed effective in reclaiming contaminated sites. This study investigates the ability of Sporobolus pyramidalis and Sacciolepis africana grasses to bioaccumulate copper, cadmium, chromium and lead in field studies using Challawa-contaminated soil (CCS). The presence of important phenolic acids and their derivatives was detected in both S. pyramidalis and S. africana respectively using Liquid chromatography mass spectrometry (LC-MS). The relative growth rate (RGR) of both plant species were significantly (p ˂ 0.05) lower than the control, with S. africana having a better tolerance ability to heavy metals toxicity than S. pyramidalis with RGR indices of 0.0109 ± 0.00 day^-1 and 0.0077 ± 0.00 day^-1 respectively. Moreover, both species had significant reductions (p ˂ 0.05) in their chlorophyll concentrations, with S. africana being more affected. The bioaccumulation studies revealed that, S. africana accumulated substantial amount of Cr in shoots than in roots, having translocation factor (TF) above the critical value (1.0). However, S. pyramidalis accumulated substantial amount of Cd and Pb in shoots than in roots, having TF greater than the critical value (1.0). This study demonstrated that both S. africana and S. pyramidalis are efficient hyperaccumulators that can be applied for phytoextraction of Cr and Cd, Pb respectively.

Heat stress and soil arsenic (As) contamination are resulting in severe decline in crop production around the world. The present experiment aimed to assess physiological and biochemical changes induced by the combination of As and heat stress in quinoa. Plants were grown in pots with different concentrations of As (0, 10, 20, and 30 mg kg^-1), either at ambient temperature (30/12 °C day/night) or 5 °C higher than ambient temperature. The combination of heat stress with As (30 mg kg^-1 soil) resulted in the highest decrease in shoot/root dry weight (84.1/79.1%), stomatal conductance (84.5%), and leaf relative water contents (75.6%). Heat stress also increased As accumulation in plants, and plants treated with As level of 30 mg As kg^-1, with or without heat stress failed to reach maturity. Over expression of antioxidant enzymes partly neutralized the oxidative stress in quinoa caused by As and heat stress. Accumulation of As in quinoa plant parts was in the order of root > shoot > grains. Human health risks posed by the contaminated quinoa grains were increased under the combination of As and heat stress. Hence, cultivation of quinoa genotype Puno is not suitable under high temperatures and contaminated soils with higher As levels.

Nitrogenous fertilizer (N fertilizer) is crucial to the quality of mulberry leaves. This study evaluated the influences of 4 N fertilizers on the chemical properties of paddy soil, mulberry growth, leaf quality and Cd distribution in mulberry. The results showed the soil pH was reduced with the increasing concentrations of NH₄Cl and (NH₄)₂SO₄. The soil pH for NH₄Cl and (NH₄)₂SO₄ treatments were 4.60 and 4.62 at 300 mg N/kg soil, 21.10% and 20.75% lower than that of the control, respectively. CO(NH₂)₂ increased soil organic matter (OM) and the 4 N fertilizers all increased the Cd phytoavailability with (NH₄)₂SO₄>NH₄Cl > CO(NH₂)₂>NaNO₃. (NH₄)₂SO₄ and CO(NH₂)₂ improved leaf production, total mulberry biomass and the total sugar in leaf. CO(NH₂)₂, NH₄Cl and NaNO₃ increased the crude protein content and (NH₄)₂SO₄ increased the chlorophyll content (8.10%∼20.20%). (NH₄)₂SO₄ and NH₄Cl increased the Cd concentration in leaf, stem and root. CO(NH₂)₂ increased Cd concentration in leaf and stem. All 4 N fertilizers decreased the percentage content of Cd in roots (1.80%∼37.74%) and increased it in stems (3.90%∼263.81%) and leaves (24.09%∼236.18%). The leaves from the CO(NH₂)₂ and NaNO₃ treatments met the hygienical standard for feeds. CO(NH₂)₂ and NaNO₃ could be recommended to safely utilize the Cd polluted acidic paddy soils.

Contamination of agricultural soils with cadmium (Cd) and lead (Pb) poses significant risks to forage production and food chain safety in arid and semi-arid regions. Kochia (Kochia scoparia L.) is a fast-growing, stress-tolerant forage species with potential for phytoremediation. This study evaluated the biochemical, uptake, and translocation responses of kochia roots to soil contaminated with Cd or Pb at concentrations of 25-800 mg kg^-1. Key parameters assessed included non-enzymatic antioxidants (e.g., phenols, flavonoids, proline, glycine betaine), enzymatic activities (catalase, peroxidase, superoxide dismutase, ascorbate peroxidase), hydrogen peroxide content, osmolyte accumulation (water-soluble carbohydrates and proteins), and metal bioconcentration factor (BCF), biological accumulation coefficient (BAC), translocation factor (TF), and translocation efficiency (TE %). Results demonstrated that kochia accumulated substantial Cd and Pb in roots, with maximum root concentrations correlating positively with soil levels (polynomial relationships; R² > 0.95). Cd exhibited high root-to-shoot translocation (TF up to 1.5 at 800 mg kg^-1; TE % up to 60%), while Pb was predominantly sequestered in roots (TF < 0.5; TE % < 30%). Cd induced stronger oxidative stress, evidenced by greater elevations in hydrogen peroxide (up to 115.2% increase at 800 mg kg^-1), antioxidant enzymes (e.g., ascorbate peroxidase increased 79.3% at 800 mg kg^-1), and osmoprotectants (e.g., proline 33.9%, glycine betaine 66.9%) compared to Pb (proline 27%, glycine betaine 50.1%). Biomass declined more severely under Cd (shoot dry weight reduced 83.4% at 800 mg kg^-1) than Pb (67.6%). BCF and BAC were highest at 25 mg kg^-1 (BCF > 4 for both metals) and decreased with concentration. These findings position kochia as an effective Cd phytoremediator due to high translocation, but highlight food chain risks from shoot Cd accumulation when used as forage, necessitating strict biomass management in contaminated sites.

Phytoremediation and soil washing are effective methods for the remediation of arsenic-contaminated soil. In this study, citric acid solution was utilized as a soil leaching agent for in-situ leaching of arsenic-contaminated soil via drip irrigation, aiming to explore the migration and distribution of arsenic in the soil. Hydroponic experiments were conducted to investigate the influence of citric acid on plant absorption and translocation of arsenic. Finally, intercropping of Brassica rapa L. ssp. chinensis and Zea mays L. was carried out under drip irrigation, to explore the effectiveness of citric acid as a soil leaching agent in phytoremediation of arsenic-contaminated soil. The results indicated that after drip irrigation with citric acid solution, the arsenic in the soil undergoes directional migration and exhibits differentiated distribution. Citric acid significantly affected the absorption and transport of arsenic in Brassica rapa L. ssp. chinensis and Zea mays L. Notably, the lowest arsenic content in Brassica rapa L. ssp. chinensis was observed at a citric acid concentration of 2 mmol·L^-1. After drip irrigation with 2 mmol·L^-1 citric acid solution, the arsenic content in Zea mays L. (remediation plant) increased by 23.34%, while the arsenic content in Brassica rapa L. ssp. chinensis decreased by 10.70%. As a soil leaching agent, citric acid effectively enhanced the phytoremediation of arsenic-contaminated soil.

Phytoremediation is a technique that uses plants to decontaminate polluted environments, such as soil, water and even air. Plants employ several mechanisms to remove, stabilize or degrade contaminants, depending on the nature of the pollutant and the environmental conditions. The main mechanisms include: phytoextraction, phytodegradation, phytovolatilization, phytostabilization and rhizofiltration. The uptake of heavy metals by plants is influenced by several key factors. Soil characteristics such as soil properties such as pH, organic matter content, cation exchange capacity (CEC), and texture significantly affect the mobility and bioavailability of heavy metals. For example, soil pH influences metal solubility, and acidic conditions generally increase the availability of metals. Conversely, higher organic matter and CEC can bind heavy metals, reducing their bioavailability. Different plant species and even varieties within a species exhibit varying capacities to take up and accumulate heavy metals. Some plants, known as hyperaccumulators, can tolerate and concentrate high levels of heavy metals in their tissues, making them useful for phytoremediation. In contrast, other plants may restrict the uptake or translocation of metals to aerial parts. And environmental conditions such as factors such as temperature, humidity, and the presence of other contaminants can influence the uptake of heavy metals. For example, waterlogging conditions can alter the redox state of metals, affecting their solubility and availability to plants. Furthermore, interactions with other pollutants, such as microplastics, can modify the adsorption and mobility of heavy metals in the soil-plant system. The main soil contaminants that can be treated include heavy metals (such as lead, cadmium and mercury), pesticides, solvents, hydrocarbons and explosives. In water, phytoremediation is applied to remove heavy metals, excess nutrients (such as nitrogen and phosphorus), pesticides and organic compounds. Although less common, phytoremediation can also be used to treat air pollutants, such as volatile organic compounds (VOCs) and certain gases. These can be of anthropogenic or natural origin, the former being more evident due to industrial activities, agricultural practices and low removal efficiency of conventional treatments present in water treatment plants. This study aims to analyze the potential of using phytoremediation as a way of recovering ecosystems and ensuring a healthy environment. While nanomaterials and similar compounds can enhance phytoremediation, high doses may harm plants. Further research is needed to improve phytoremediation's efficiency and feasibility for restoring contaminated soil, water, and air.

Tannery solid waste poses significant environmental challenges owing to its high metal content, especially Cr. Converting this waste into value-added byproduct i.e., biochar offers a sustainable management approach to reducing the waste load on landfill sites and also guarding the nearby fauna, flora and water bodies. This study aimed to develop metal-resistant microbial consortium loaded biochar (MCLB) by inoculating tannery solid waste biochar (BC) with consortium of ten Bacillus and/or five Trichoderma strains and their effect was evaluated on the morphological and biochemical attributes of sunflowers including metals immobilization. The soil amendment with BC at 2% rate improved the shoot height, dry biomass, and chlorophyll content in sunflowers but not in higher doses. However, the application of MCLB even at its highest concentration i.e., 10% dose showed a significant increase in shoot length (61.2%) and dry weight (656.9%) over BC only. The findings of metal bioavailability indicated that the application of MCLB having metal-resistant strains decreased the mobility of Cd, Cr, Cu, Ni, Pb and Zn into the sunflower tissues compared to BC. Moreover, MCLB enhanced the uptake of Fe and Mg which are beneficial to the plant. In addition to that, the results for phenolic and proline content demonstrated a considerable decrease by MCLB indicating less stress response as compared to BC. Therefore, these findings highlight the potential of MCLB as a sustainable soil amendment for improving the growth attributes of oil-yielding sunflower varieties by using tannery solid waste biochar while decreasing the uptake of nonessential metals. By pyrolyzing the tannery solid waste into biochar, this approach contributes to a circular economy and environmental remediation practices.

Remediation of heavy metal pollution is essential for safeguarding ecological integrity and public health. The present work aimed to prepare a novel biochar from Eucalyptus Camaldulensis leaves (EC-biochar) for the effective removal of Cd²⁺ and Pb²⁺ cations, as representative heavy metals, from aqueous solutions. The adsorption performance of Cd²⁺ and Pb²⁺ cations by EC-biochar was assessed by varying different operating parameters (e.g. pH, temperature, EC-biochar dose, adsorption time, and adsorbate concentration). The maximum removal efficiencies of Pb²⁺ (83.8%) and Cd²⁺ (89.6%) ions were achieved at pH 4.5. The pseudo-second order and Langmuir isotherm models satisfactorily predict the adsorption of Pb²⁺ and Cd²⁺ cations onto EC-biochar. The negative values of ΔG° and ΔH° demonstrated that the adsorption process is spontaneously feasible and exothermic. It is also worth pointing out that the regeneration/reuse study revealed that the as-prepared EC-biochar maintained an excellent adsorption performance after five reuse cycles, demonstrating its suitable reusability. These findings demonstrate that the EC-biochar can serve as an inexpensive, effective and recyclable adsorbent for treating heavy metal-laden effluents.

The discharge of wastewater containing toxic pollutants, such as lead [Pb(II)] and cadmium [Cd(II)], into water bodies is one of the most critical challenges nowadays. Apart from this, the daily generation of organic waste like vegetable, fruit, and flower waste in cities is increasing constantly. Therefore, a novel approach was adopted in this study that used flower waste (Tagetes erecta L. marigold) for the metal removal from polluted water with a view to manage flower waste and metal contaminants simultaneously. The characterization of prepared waste of T. erecta flowers and its biosorption capacity for Cd and Pb were investigated through various techniques viz., atomic absorption spectrophotometer (AAS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), and Fourier transform infrared analysis (FTIR). Experiments for adsorption isotherm were carried out at the room temperature and the performance was determined using Langmuir and Freundlich adsorption models. Equilibrium data was confirmed to follow pseudo second order kinetics. The maximum adsorption capacities of flower waste for Cd(II) and Pb(II) were 52.6 and 21.74 mg g^-1, respectively. The study findings indicated that the optimum pH and time for the most effective elimination were pH 6 and 150 min, respectively, for Pb (80%) and Cd (91.8%).