Potential of Vetiveria zizanoides L. Nash for phytoremediation of plutonium ((239)Pu): Chelate assisted uptake and translocation

Unraveling the nuclear isotope tapestry: Applications, challenges, and future horizons in a dynamic landscape

Nuclear isotopes, distinct atoms characterized by varying neutron counts, have profoundly influenced a myriad of sectors, spanning from medical diagnostics and therapeutic interventions to energy production and defense strategies. Their multifaceted applications have been celebrated for catalyzing revolutionary breakthroughs, yet these advancements simultaneously introduce intricate challenges that warrant thorough investigation. These challenges encompass safety protocols, potential environmental detriments, and the complex geopolitical landscape surrounding nuclear proliferation and disarmament. This comprehensive review embarks on a deep exploration of nuclear isotopes, elucidating their nuanced classifications, wide-ranging applications, intricate governing policies, and the multifaceted impacts of their unintended emissions or leaks. Furthermore, the study meticulously examines the cutting-edge remediation techniques currently employed to counteract nuclear contamination while projecting future innovations in this domain. By weaving together historical context, current applications, and forward-looking perspectives, this review offers a panoramic view of the nuclear isotope landscape. In conclusion, the significance of nuclear isotopes cannot be understated. As we stand at the crossroads of technological advancement and ethical responsibility, this review underscores the paramount importance of harnessing nuclear isotopes' potential in a manner that prioritizes safety, sustainability, and the greater good of humanity.

Vetiver grass cleans up arsenic contaminated field for subsequent safe cultivation of rice with low arsenic in grains: A two year field study

The presence of high concentrations of arsenic (As) in agricultural soils and its subsequent accumulation in rice crop is a serious issue threatening sustainability of agriculture and human health. In the present work, remediation of As contaminated field in Nadia, West Bengal, India was done through the cultivation of Vetiver (Vetiveria zizanoides L. Nash) and the same field was subsequently used for rice (Oryza sativa L.) cultivation. The results showed that V. zizanoides could reduce As concentrations in the field to bring it lower than the maximum permissible limit (20 mg kg-1) in 11 months' time. The rice plants grown in remediated field showed improvement in growth and photosynthesis parameters as compared to that of contaminated field. Importantly, yield related parameters (filled seed, 1000 grain weight, number of panicles etc.) were also significantly higher in remediated field than that in contaminated field. Arsenic concentration in roots, shoot, husk and grains of rice was found to be significantly lower in remediated field than in contaminated field. Grain As decreased from 0.75 to 0.77 μg g-1 dw in contaminated field to 0.15-0.18 μg g-1 dw. In conclusion, replacing rice for single year with V. zizanoides crop can significantly remediate the field and can be a viable option.

Engaging One Health in Heavy Metal Pollution in Some Selected Nigerian Niger Delta Cities. A Systematic Review of Pervasiveness, Bioaccumulation and Subduing Environmental Health Challenges

The Niger Delta environment is under serious threat due to heavy metal pollution. Many studies have been conducted on the heavy metal contamination in soils, water, seafood and plants in the Niger Delta ecosystem. However, there is a lack of clear understanding of the health consequences for people and strategies for attaining One Health, and a dispersion of information that is accessible. The study focused on investigating the contamination levels, distributions, risks, sources and impacts of heavy metals in selected regions of the Niger Delta. Prior studies revealed that the levels of certain heavy metals, including Cd, Pb, Cu, Cr, Mn, Fe and Ni, in water, sediment, fish and plants in most Niger Delta ecosystems were higher than the acceptable threshold attributed to various anthropogenic stressors. In the reviewed Niger Delta states, ecosystems in Rivers state showed the highest concentrations of heavy metals in most sampled sites. Groundwater quality was recorded at concentrations higher than 0.3 mg/L World Health Organization drinking water guideline. High concentrations of copper (147.915 mg/L) and zinc (10.878 mg/L) were found in Rivers State. The heavy metals concentrations were greater in bottom-dwelling organisms such as bivalves, gastropods and shrimp than in other fishery species. Heavy metal exposure in the region poses risks of communicable and non-communicable diseases. Diverse remediation methods are crucial to reduce contamination levels, but comprehensive strategies and international cooperation are essential to address the health hazards. Actively reducing heavy metals in the environment can achieve One Health objectives and mitigate disease and economic burdens.

Emerging paradigms into bioremediation approaches for nuclear contaminant removal: From challenge to solution

The release of radionuclides, including Cesium-137 (137Cs), Strontium-90 (90Sr), Uranium-238 (238U), Plutonium-239 (239Pu), Iodine-131 (131I), etc., from nuclear contamination presents profound threats to both the environment and human health. Traditional remediation methods, reliant on physical and chemical interventions, often prove economically burdensome and logistically unfeasible for large-scale restoration efforts. In response to these challenges, bioremediation has emerged as a remarkably efficient, environmentally sustainable, and cost-effective solution. This innovative approach harnesses the power of microorganisms, plants, and biological agents to transmute radioactive materials into less hazardous forms. For instance, consider the remarkable capability demonstrated by Fontinalis antipyretica, a water moss, which can accumulate uranium at levels as high as 4979 mg/kg, significantly exceeding concentrations found in the surrounding water. This review takes an extensive dive into the world of bioremediation for nuclear contaminant removal, exploring sources of radionuclides, the ingenious resistance mechanisms employed by plants against these harmful elements, and the fascinating dynamics of biological adsorption efficiency. It also addresses limitations and challenges, emphasizing the need for further research and implementation to expedite restoration and mitigate nuclear pollution's adverse effects.

Roles and significance of chelating agents for potentially toxic elements (PTEs) phytoremediation in soil: A review

Phytoremediation is a biological remediation technique known for low-cost technology and environmentally friendly approach, which employs plants to extract, stabilise, and transform various compounds, such as potentially toxic elements (PTEs), in the soil or water. Recent developments in utilising chelating agents soil remediation have led to a renewed interest in chelate-induced phytoremediation. This review article summarises the roles of various chelating agents and the mechanisms of chelate-induced phytoremediation. This paper also discusses the recent findings on the impacts of chelating agents on PTEs uptake and plant growth and development in phytoremediation. It was found that the chelating agents have increased the rate of metal absorption and translocation up to 45% from roots to the aboveground plant parts during PTEs phytoremediation. Besides, it was also explored that the plants may experience some phytotoxicity after adding chelating agents to the soil. However, due to the leaching potential of synthetic chelating agents, the use of organic chelants have been explored to be used in PTEs phytoremediation. Finally, this paper also presents comprehensive insights on the significance of using chelating agents through SWOT analysis to discuss the advantages and limitations of chelate-induced phytoremediation.

A strategy for bioremediation of nuclear contaminants in the environment

Radionuclides released from nuclear contamination harm the environment and human health. Nuclear pollution spread over large areas and the costs associated with decontamination is high. Traditional remediation methods include both chemical and physical, however, these are expensive and unsuitable for large-scale restoration. Bioremediation is the use of plants or microorganisms to remove pollutants from the environment having a lower cost and can be upscaled to eliminate contamination from soil, water and air. It is a cheap, efficient, ecologically, and friendly restoration technology. Here we review the sources of radionuclides, bioremediation methods, mechanisms of plant resistance to radionuclides and the effects on the efficiency of biological adsorption. Uptake of radionuclides by plants can be facilitated by the addition of appropriate chemical accelerators and agronomic management, such as citric acid and intercropping. Future research should accelerate the use of genetic engineering and breeding techniques to screen high-enrichment plants. In addition, field experiments should be carried out to ensure that this technology can be applied to the remediation of nuclear contaminated sites as soon as possible.

A critical review on the phytoremediation of heavy metals from environment: Performance and challenges

Phytoremediation is an effective, green and economical technique. Different types of phytoremediation methods can be used for the reduction of heavy metal contaminations, such as phytoextraction, phytovolatilization, phytostabilization and phytofiltration. The biomass of plants and the bioavailability of heavy metals in soil are the key factors affecting the efficiency of phytoremediation. It's worth noting that the low remediation efficiency and the lack of effective disposal methods for contaminated biomass have limited its development and application. At present, biological, physical, chemical, agronomic and genetic approaches have been used to enhance phytoremediation. Disposal methods of contaminated biomass usually include pyrolysis, incineration, composting and compaction. They are effective, but are costly and have security problems. Improper disposal of contaminated biomass can lead to leaching of heavy metals. The leaching possibility of different forms of heavy metal in plants is different. Hence, it has great significance to explore the different forms of heavy metals in plants which can help to explore appropriate disposal methods. According to the challenges of phytoremediation, we put forward some views and recommendations for the sustainable and rapid development of phytoremediation technology.

NTA-assisted mineral element and lead transportation in Eremochloa ophiuroides (Munro) Hack

Lead (Pb) is one of the most toxic and harmful pollutants to the environment and human health. Centipedegrass (Eremochloa ophiuroides (Munro) Hack.), an excellent ground cover plant for urban plant communities, exhibits the outstanding lead tolerance and accumulation. Nitrilotriacetic acid (NTA) is an environmentally friendly chelating agent that strengthens phytoremediation. This study explored the effects of different NTA concentrations on the absorption and transportation of mineral elements and Pb in centipedegrass. Following exposure to Pb (500 μM) for 7 days in hydroponic nutrient solution, NTA increased root Mg, K, and Ca concentrations and shoot Fe, Cu, and Mg concentrations and significantly enhanced the translocation factors of mineral elements to the shoot. Although NTA notably decreased root Pb absorption and accumulation, it significantly enhanced Pb translocation factors, and the Pb TF value was the highest in the 2.0 mM NTA treatment. Furthermore, the shoot translocation of Pb and mineral elements was synergistic. NTA can support mineral element homeostasis and improve Pb translocation efficiency in centipedegrass. Regarding root radial transport, NTA (2.0 mM) significantly promoted Pb transport by the symplastic pathway under the treatments with low-temperature and metabolic inhibitors. Meanwhile, NTA increased apoplastic Pb transport at medium and high Pb concentrations (200-800 μM). NTA also enhanced the Pb radial transport efficiency in roots and thus assisted Pb translocation. The results of this study elucidate the effects of NTA on the absorption and transportation of mineral elements and Pb in plants and provide a theoretical basis for the practical application of the biodegradable chelating agent NTA in soil Pb remediation.

Phytoextraction of arsenic using a weed plant Calotropis procera from contaminated water and soil: growth and biochemical response

Developing effective and environment-friendly alternatives to remove arsenic (As) from soil and water systems is of great importance and phytoremediation may be a promising alternative in this direction. Weeds have wide geographical distribution, not a part of food chain, well adapted to adverse conditions and reported to grow at various heavy metal contaminated sites. The present work delineates potential of a weed plant Calotropis procera L. for the remediation and translocation of As from water and soil and this plant has been found efficient in remediating significant quantities of As after 15 and 30 d when exposed to a range of concentrations. Moreover, As accumulation was found more in shoots than the roots when exposed to higher As levels for 30d having translocation factor >1 and make this plant suitable for phytoextraction of As. Effect of As on plant growth, photosynthetic pigments and lipid peroxidation in response to As is also presented here. The activities of antioxidant enzymes, superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase and catalase were found to increase in response to As stress. High As accumulation and tolerance potential of C. procera from artificially As contaminated water and soil coupled with good growth and its phytoextraction ability suggests the feasibility of this plant for the phytoremediation of As from contaminated water and soils.

Potential of higher plants, algae, and cyanobacteria for remediation of radioactively contaminated waters

The potential of photosynthetic organisms to remediate radioactively contaminated water was evaluated for scenarios related to nuclear installations and included the following radionuclides: ¹³⁷Cs, ¹³⁴Cs, ¹³⁶Cs, ⁹⁰Sr, ¹³¹I, ²³⁹Pu, ²⁴¹Am, ¹³²Te/¹³²I, ⁵⁸Co, ⁶⁰Co, ⁵¹Cr, ^110mAg, ⁵⁴Mn, ¹²⁴Sb, ⁵⁹Fe, ⁶⁵Zn, ⁹⁵Zr, and ⁹⁵Nb. An extensive literature review was undertaken leading to the creation of a database including more than 20,000 entries from over 100 references in which terrestrial and aquatic plants, macro- and microalgae, cyanobacteria and biosorbents derived from these organisms were used to clean water from these specific radionuclides or their stable isotopes. In a first phase, the remediation potential of the organisms and biosorbents was evaluated for the individual elements based on parameters such as plant uptake, removal percentage, and bioconcentration factor, and for two radionuclide mixtures based on the ability of the organisms/biosorbents to work under mixture conditions. As the experimental and environmental conditions will influence the performance of the organisms and biosorbents, a literature-based evaluation of the most influencing or restricting parameters was made and water pH, competing ions, and the chemical modification of biosorbents showed to be of major importance. Finally, the most promising organisms and biosorbents were identified using a specifically developed selection procedure taking into account their performance and robustness. Ranking was done based on clear criteria with a distinct weight and scoring scheme. As such, 20 organisms/biosorbents were identified that showed high potential to clean waters contaminated with (mixtures of) radionuclides related to nuclear installations and which can be used for further experimental investigations.

Phytomanagement of radionuclides and heavy metals in mangrove sediments of Pattani Bay, Thailand using Avicennia marina and Pluchea indica

This study determines uptake and accumulation of radionuclides and heavy metals by Pluchea indica and Avicennia marina and evaluates phytoremediation potential via greenhouse and field experiments. P. indica and A. marina are considered excluders for ⁴⁰K and ²⁶²Ra, and Pb since roots accumulated them in higher quantities compared to other plant parts, and the bioconcentration factor (BCF) and transfer factor (TF) values for Pb, and ⁴⁰K and ²⁶²Ra were >1, respectively. Absorbed dose rate in air (D) showed significant values in sediments, which were generally over the maximum recommended value of 55nGyh^-1. Phytostabilization of radionuclides and heavy metals may serve as an appropriate strategy for mangrove-polluted areas. D values in sediments were considered sufficiently high to recommend long-term monitoring. Radionuclide activities may increase in the food chain via uptake and accumulation of edible plants, ultimately resulting in harm to human health.

Mercury accumulation plant Cyrtomium macrophyllum and its potential for phytoremediation of mercury polluted sites

Cyrtomium macrophyllum naturally grown in 225.73 mg kg^-1 of soil mercury in mining area was found to be a potential mercury accumulator plant with the translocation factor of 2.62 and the high mercury concentration of 36.44 mg kg^-1 accumulated in its aerial parts. Pot experiments indicated that Cyrtomium macrophyllum could even grow in 500 mg kg^-1 of soil mercury with observed inhibition on growth but no obvious toxic effects, and showed excellent mercury accumulation and translocation abilities with both translocation and bioconcentration factors greater than 1 when exposed to 200 mg kg^-1 and lower soil mercury, indicating that it could be considered as a great mercury accumulating species. Furthermore, the leaf tissue of Cyrtomium macrophyllum showed high resistance to mercury stress because of both the increased superoxide dismutase activity and the accumulation of glutathione and proline induced by mercury stress, which favorited mercury translocation from the roots to the aerial parts, revealing the possible reason for Cyrtomium macrophyllum to tolerate high concentration of soil mercury. In sum, due to its excellent mercury accumulation and translocation abilities as well as its high resistance to mercury stress, the use of Cyrtomium macrophyllum should be a promising approach to remediating mercury polluted soils.

Investigation of arsenic accumulation and biochemical response of in vitro developed Vetiveria zizanoides plants

Vetiver grass (Vetiveria zizanoides L. Nash) is found to be a suitable candidate for the phytoremediation of heavy metals. An investigation of arsenic (As) accumulation, translocation and tolerance was conducted in V. zizanoides plantlets upon exposure to different concentrations of arsenic (10, 50, 100 and 200µM) for 7 and 14 d. V. zizanoides plants were found effective in remediation of As, maximum being at 200µM after 14 d of exposure. The results of TBARS and photosynthetic pigments demonstrated that plants did not experience significant toxicity at all the concentrations of As after 7 days, however an increase in their level was found after 14 d. The up-regulation of antioxidant enzyme activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), catalase (CAT) and glutathione s-transferase (GST) in a coordinated and complementary manner enhanced tolerance to plants against arsenic induced oxidative stress. Taken together, the results indicated that in vitro developed plants of V. zizanoides have the potential to remediate and tolerate varying levels of As.

Phytoextraction of potentially toxic elements by six tree species growing on hazardous mining sludge

The aim of the study was to compare the phytoextraction abilities of six tree species (Acer platanoides L., Acer pseudoplatanus L., Betula pendula Roth, Quercus robur L., Tilia cordata Miller, Ulmus laevis Pall.), cultivated on mining sludge contaminated with arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), thallium (Tl), and zinc (Zn). All six tree species were able to survive on such an unpromising substrate. However, A. platanoides and T. cordata seedlings grown on the polluted substrate showed significantly lower biomass than control plants (55.5 and 45.6%, respectively). As, Cd, Cu, Pb, and Tl predominantly accumulated in the roots of all the analyzed tree species with the following highest contents: 1616, 268, 2432, 547, and 856 mg kg^-1, respectively. Zn was predominantly localized in shoots with the highest content of 5801 and 5732 mg kg^-1 for U. laevis and A. platanoides, respectively. A. platanoides was the most effective in Zn phytoextaction, with a bioconcentration factor (BCF) of 8.99 and a translocation factor (TF) of 1.5. Furthermore, with the exception of A. pseudoplatanus, the analyzed tree species showed a BCF > 1 for Tl, with the highest value for A. platanoides (1.41). However, the TF for this metal was lower than 1 in all the analyzed tree species. A. platanoides showed the highest BCF and a low TF and could, therefore, be a promising species for Tl phytostabilization. In the case of the other analyzed tree species, their potential for effective phytoextraction was markedly lower. Further studies on the use of A. platanoides in phytoremediation would be worth conducting.

Phytostabilisation potential of giant reed for metals contaminated soil modified with complex organic fertiliser and fly ash: A field experiment

An orthogonal field experiment of giant reed (Arundo donax) modified with organic complex fertiliser (OCF), and OCF and fly ash (O&F), at different planting densities was carried out in metal-contaminated soil. The available percentage of arsenic (As) and lead (Pb) in soil decreased from 8.45% to 2.19% and from 29.6% to 13.5% by OCF, respectively, and that of cadmium (Cd) was reduced from 25.3% to 6.49% by O&F. The total biomass of giant reed was 631g per individual following application of O&F in contaminated soil. The accumulation of As, Cd, and Pb in giant reed was 1.57, 4.06, and 11.25mg per individual. Urease and sucrase activity were 87.4NH₄-Nμg/gd and 63.1glucosemg/gd in response to the treatments modified using OCF, while the highest dehydrogenase activity was 101 TPF (triphenyltetrazolium formazan) μg/gd in the treatments modified using O&F. Dominant bacteria (frequency>50%) were enriched with increasing planting density of giant reed. These results indicate that the phytostabilisation of metal-contaminated soil by giant reed could be improved by the application of O&F or OCF.