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Phytoextraction of Metals from Contaminated Soil: A Review of Plant/Soil/Metal Interaction and Assessment of Pertinent Agronomic Issues

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... According to Tangahu et al. [17] , plant roots, aided by plant-produced chelating agents and plant-induced pH changes and redox reactions, can solubilize and take up micronutrients (including heavy metals) from very low levels in the soil. Plants influence the removal of heavy metals by modifying the rhizosphere and secreting exudates which enhance the activities of rhizospheric microbes and the bioavailability of the metals thus increasing their uptake [37] . The positive correlation between the rate of heavy metal loss, level of accumulation, and bioconcentration factor observed in this study, suggests the rate of heavy metal loss in this study is consistent with the amount of heavy metal accumulated in the plant. ...
... The chemical characteristics of the contaminant, chemical characteristics of the medium, characteristics of the plant species, and environmental conditions also affect phytoremediation efficiency [37] . As was stated by Liang et al. [37] , the concentration of heavy metals in soil solution can be increased by reducing the pH and CEC content of the soil which suggests that the relatively low CEC of the mechanic workshop could be the cause for higher percentage and rate of loss of the heavy metals from such soil than from the refuse dump soil as we recorded in this study. ...
... The chemical characteristics of the contaminant, chemical characteristics of the medium, characteristics of the plant species, and environmental conditions also affect phytoremediation efficiency [37] . As was stated by Liang et al. [37] , the concentration of heavy metals in soil solution can be increased by reducing the pH and CEC content of the soil which suggests that the relatively low CEC of the mechanic workshop could be the cause for higher percentage and rate of loss of the heavy metals from such soil than from the refuse dump soil as we recorded in this study. This corroborates the reports of Salem et al. [42] which showed that CEC has a negative correlation with the copper and cadmium content of the soil. ...
Article
This study was investigated the potential of Amaranthus spinosus for the remediation of heavy metal contaminated soils a mechanic workshop and refuse dumpsites. The plant was grown in each soil for 12 weeks. The heavy metals were extracted from the samples using HNO3 digestion and analyzed using atomic absorption spectrometry (AAS) equipment (Perkin Elmer Analyst 460). The growth of A. spinosus contributed to an enhanced loss of the heavy metals from the soils. The loss of the heavy metals due to the growth of A. spinosus was more in soils from the refuse dumpsite than in the soils from the mechanic workshop. The rate of heavy metal loss was faster in the soil from mechanic workshop mechanic workshop than in the soil from the dumpsite. The trend of the rate of heavy metals loss was Cu>Zn>Pb>Cd for vegetated soil and Zn>Cu>Pb>Cd for non-vegetated soil. The rate of the heavy metal loss shows it will take lesser time to achieve 100% loss of the heavy metals in the vegetated soil than in the non-vegetated soils. There was no statistical difference between the loss of the heavy metals from the soils of the mechanic workshop and refuse dumpsite (p>0.05). The results of this study indicated that A. spinosus with BCF values greater than 1 for Zn and Cu suggest that the plant uses hyperaccumaulation as the mechanism of remediation of the metals. The percentage loss of the heavy metals from the soils had a negative correlation with the amounts of heavy metals accumulated in the tissues of the plant, the rate of loss, and the bioconcentration factors. The ability of A. spinosus to be considered for phytoremediation has to be viewed with caution, as the translocation factor index indicates that all the metals investigated in this study were being translocated to the aerial parts of the plant.
... Heavy metals are conventionally defined as elements with metallic properties and an atomic number is more than 20 [49] [27]. Soil pollution by heavy metals has a harmful impact on biological activities in soil because heavy metals are not biodegraded easily. ...
... Further, for the proper development and complete the life cycle, plants must acquire not only macronutrients (N, P, K, S, Ca, and Mg), but also micronutrients or heavy metals (i.e. Co, Cu, Fe, Mn, Mo, Ni, and Zn) that are essential for healthy plant growth [49] , and crops may be supplied with these as an addition to the soil or as a foliar spray. The concentration of heavy metals in fertilizers and soil amendments is presented in table 3. ...
Article
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Heavy metals are the most important soil contaminants in the environment. Heavy metals are the integrated components of the biosphere and thus occur naturally in soils and plants. Heavy metals (Cd, Cr, Cu, Hg, Pb, and Zn) have occurred widely as a result of human, agricultural and industrial activities which is responsible for the contamination of soils. Some of these metals are micro-nutrients that are necessary for plant growth, such as Zn, Cu, Mn, Ni, and Co, while others have unknown biological functions, such as Cd and Pb. Agricultural activities involve the addition of inorganic fertilizers, insecticides, pesticides, and amendments to the soil for increasing productivity are responsible for soil contamination/pollution. Water used for irrigation and the release of industrial effluents in water resources pollute the soil with solid wastes, heavy metals, and several other organic and inorganic substances. Reclamation of such contaminated soils through the phytoremediation method was found to be the cheapest and an effective method for extraction or removal of pollutants from contaminated soils.
... Chen et al. [7] suggested that long term trace metals contamination negatively affects the microbial biodiversity and their activity. Unlike organic contaminants, trace metals cannot be degraded [8] [9]. In addition, as far as clean-up of soils contaminated by metal trace metals is concerned, conventional remediation techniques fall short of expectation due to their high cost [10], whereas phytoremediation can be considered as an economical and effective alternative in some cases of metal trace elements pollution [8]. ...
... Unlike organic contaminants, trace metals cannot be degraded [8] [9]. In addition, as far as clean-up of soils contaminated by metal trace metals is concerned, conventional remediation techniques fall short of expectation due to their high cost [10], whereas phytoremediation can be considered as an economical and effective alternative in some cases of metal trace elements pollution [8]. Furthermore, those conventional remediation technologies (soil flushing/washing, vitrification, surface capping, landfilling, electro-kinetic extraction) influence soil properties, fertility and biodiversity [11]. ...
... Trace metals are essential nutrients but are required in small quantities. The de ciency of trace elements (Cu, Co, Fe, Mn, Mo, Ni and Zn) negatively affects the growth of plants(Lasat et al. 2000). The concentration of trace metals could be increased in de cient soils and improve crop yield using inorganic fertilizers(Lasat et al. 2000). ...
... The de ciency of trace elements (Cu, Co, Fe, Mn, Mo, Ni and Zn) negatively affects the growth of plants(Lasat et al. 2000). The concentration of trace metals could be increased in de cient soils and improve crop yield using inorganic fertilizers(Lasat et al. 2000). Wuana and Okieimen (2011) posited that Cu de cient soils for cereal production are occasionally treated with Cu whilst Mn is supplied to root crops. ...
Preprint
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Potentially toxic metals in soils are a threat to food security and harmful to human because it enters the food chain through crop uptake. Hence, it is critical to know the levels of potentially toxic metals in soils due to agricultural land use patterns and how they can be removed from the soil. This review discussed the effect of different land-use patterns on heavy metal accumulation, their removal using biochar. A desktop review which employed PRISMA was used to put together information from peer-reviewed papers including journal articles, books, thesis and reports. It was shown that potentially toxic metals mainly found in the soil include; As, Cu, Cd, Zn, Cr, Co, Ni, Sb, Hg, Th, Pb, Si, and Se. The sources of these potentially toxic metals accumulation in soils were organic and inorganic fertilizer application, irrigation, pesticides and weedicides application and atmospheric deposition. However, different land-use patterns (greenhouse field, vegetable field soils, forest field, and maize field soil) had a significant accumulation of heavy metals (Cr, Ni, Cu, As, Cd, and Zn) due to increasing crop yield through the application of fertilizers and pesticides. Biochar was found to be effective in the removal of 18 to 40% of these potentially toxic metals from the soil. The mechanisms of removal were; precipitation, physical sorption, complexation, and ion exchange and electrostatic interaction. It can be concluded that biochar applied solely or in addition to compost has strong stability to remove heavy metals accumulated in soils due to land use patterns.
... Heavy metals are those elements that have atomic number greater than twenty and a specific gravity more than one (Lasat, 2000). They present in the environment in a very low concentration (ppm). ...
... Indeed, the achieved cost here evaluated can be halved to approximately USD 27 per ton by neglecting the cost of monitoring. In each case, the phytoremediation cost was lower than that necessary for performing other conventional remediation techniques [93,94]. For instance, the employment of physical-chemical techniques (i.e., USD 100-500 per ton), such as soil washing, requires a high cost for extracting agents (e.g., surfactants, chelating agents), which should be further increased by the treatment of spent soil washing solution (e.g., about USD 50 per ton) [24]. ...
Article
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This study proposes the phytoremediation of phenanthrene (PHE)-, pyrene (PYR)-, and copper (Cu)-contaminated soil by Cannabis sativa L. The experimental campaign was conducted in 300 mL volume pots over a 50 d period using different initial polycyclic aromatic hydrocarbon (PAH) concentrations, i.e., 100 (PC1), 200 (PC2), and 300 (PC3) mg ƩPAHs kg−1 dry weight of soil, while maintaining a constant Cu concentration of 350 mg∙kg−1. PHE and PYR removal was 93 and 61%, 98 and 48%, and 97 and 36% in PC1, PC2, and PC3, respectively, in the greenhouse condition. The highest Cu extraction amounted to 58 mg∙kg−1. In general, the growth of C. sativa L. under the PC1, PC2, and PC3 conditions decreased by approximately 25, 65, and 71% (dry biomass), respectively, compared to the uncontaminated control. The present study is aimed at highlighting the phytoremediation potential of C. sativa L. and providing the preliminary results necessary for future field-scale investigations.
... Phytoremediation is an emerging phytotechnology which uses plants in the removal, reduction, immobilization and degradation of heavy metals in the soil (Lasat 1999). It is economically, ecologically, socially ...
Article
Potential toxic elements, such as Arsenic (As), Cadmium (Cd), Copper (Cu), Lead (Pb), and Zinc (Zn) are commonly left behind after mining operation. Being non-biodegradable, these elements serve as source of contamination for the soil and water ecosystems and create hazards to human health. This research work evaluated the phyto extracting ability for potential toxic elements by four endemic tree species, such as Betula pendula (Birch), Carpinus betulus (Hornbean), Fagus sylvatica (Beech), and Salix caprea (Goat willow). These tree species are predominantly growing in an abandoned mining spoil sites in Mátra Mountains, Hungary. Plant and soil samples were collected in the field and analyzed using inductively coupled plasma-atomic emission spectrometry (ICP-OES) method. The soil was highly contaminated with heavy metals, such as Pb, As, and Zn which were 10 to 60 times more than the typical non-contaminated Hungarian soil. Among the trees evaluated, Carpinus betulus showed the highest potential for Pb dendroremediation, with a mean concentration value of 4071.67±45.71 mg kgˉ¹ dry weight in roots, 439.05±1.06 mg kgˉ¹ dry weight in stems and 92.53±0.73 mg kgˉ¹ dry weight in leaves. Betula pendula and Salix caprea bioaccumulated 475.575±2.219 and 395.97±1.43 mg kgˉ¹ dry weight of Zn in their leaf biomass. Both trees had a Bio-concentration Factor (BCF) value of greater than 1.0 but less than 10 which classified them as potential phytoextractors of Zn. Salix caprea gave the highest Translocation Factor (Tf) for Cd while Betula pendula gave the highest Tf for Zn.
... Cultivating and harvesting medicinal plants in close proximity to industrial locations that use these metals and their compounds, as well as regions where these metals have been improperly disposed of, is strictly banned to protect the purity and safety of herbal remedies. This is because plants from these areas are prone to high amounts of heavy metals, posing a risk of human contamination if ingested [94,95]. Interestingly, heavy metal contamination screening of plant extracts, herbal formulation products, and medicinal plants in general is of critical medical value and must be given top priority in phytotherapy. ...
Chapter
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Dhatupaushtik Churna is a polyherbal powdered formulation that contains equal amounts of Gokhru (Tribulus terrestris L.; Family: Zygophyllaceae), Ashwagandha (Withania somnifera L.; family: Solanaceae), and Safed musli (Chlorophytum borivilianum L.; Family: Asparagaceae) and is used to treat a myriad of ailments, including premature ejaculation, weakness
... The most common heavy metals in soil are Pb, Hg, Cd, Cr, Cu, Ni and Zn, which they are needed for plant growth [15]. In Ledulu lake Cr and Zn were measured in all aquatic plant species. ...
... Goussen et al. (2016) resaltan que la mayoría de los estudios y proyectos relacionados con el ambiente se limitan a reducir los problemas a unas cuantas causas de esta compleja problemática y sus efectos sobre el ecosistema. En el caso de los jales mineros, la mayor parte atiende solo a la contaminación producida por estos , y la solución, por lo regular, se enfoca al uso de la biorremediación por ser la estrategia de menor costo y que requiere menor esfuerzo en su implementación (Lasat, 1999;Mench et al., 2010;Parraga-Aguado et al., 2013;Tőzsér et al., 2017;Chen et al., 2019). Resulta preocupante que algunos investigadores sugieran que "Latinoamérica al ser tan diversa tiene un gran potencial para utilizar las especies como bioacumuladoras" (Guerra Sierra et al., 2021). ...
Article
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Antecedentes y Objetivos: México presenta acumulaciones de materiales tóxicos e inestables desechados por la minería, llamados jales, representando un riesgo potencial y efectivo para los ecosistemas y la sociedad. La restauración ecológica en combinación con otras estrategias de mitigación ofrece una alternativa para disminuir estos impactos ambientales y revertir la degradación del ecosistema por los jales. Este trabajo plantea algunas consideraciones y propone una metodología para aplicar la restauración ecológica a los jales.Métodos: Se describieron las afectaciones y riesgos ocasionados por el depósito de jales a partir de las características de los materiales y del ecosistema donde se depositan, aplicando y adecuando criterios como los utilizados en la Evaluación del Impacto Ecológico. A partir de esto, se plantearon algunas consideraciones para mitigar los jales. También se analizaron las limitaciones de algunas técnicas de mitigación con organismos o materia orgánica, por sus impactos colaterales potenciales.Resultados clave: La propuesta metodológica considera acciones de mitigación de un jal que integren al ecosistema y su funcionamiento, dirigidos hacia una restauración ecosistémica. Por una parte, estos lineamientos consideran aspectos relacionados con la toxicidad y estabilidad de los jales y, por la otra, características y procesos ecosistémicos afectados por su depósito. Esta propuesta considera diez pasos que incorporan distintos aspectos que deben abordarse para la restauración en los depósitos de jales.Conclusiones: Mediante un enfoque ecosistémico, como en la restauración ecológica, se resuelven los problemas ambientales de contaminación e inestabilidad de los jales. Evitando también los impactos colaterales de las propias estrategias de mitigación como la creación de trampas ecológicas o haciendo biodisponibles los contaminantes, introduciéndolos a la cadena trófica sin compensar los impactos ecosistémicos provocados por su depósito.
... La disposición de la biomasa después de ser utilizada para la remediación de suelos contaminados es una de las mayores preocupaciones de la fitorremediación por lo que es considerado una desventaja de esta tecnología, sin embargo, (Hui Awa S. & Hadibarata T., 2020, McIntyre, T. , 2003Lasat, M. M, 1999) mencionan que la biomasa debe ser manejada y darle una disposición adecuada de acuerdo a las regulaciones del país, puede ser depositada en un vertedero para desechos peligrosos ya que estas plantas poseen altas concentraciones de metales tóxicos que fueron removidos del suelo. ...
Article
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El presente artículo tiene como objetivo proporcionar una descripción de los conceptos básicos de la fitorremediación como una tecnología amigable y viable para la remediación de los suelos por metales pesados. Mediante la recopilación de documentación en base de datos confiables y una revisión de literatura disponible, se incluyeron publicaciones vinculados a la fitorremediación de sitios contaminados. Dentro de la fitorremediación existen diferentes estrategias como la fitoextracción, fitoestabilización y fitovolatilización, que poseen ventajas como la remoción permanentemente de los metales del suelo sin alterar la calidad del suelo, contribuye a restaurar la vegetación del sitio y reducir la erosión del suelo, además, se puede aplicar de manera in situ o e x situ. Sin embargo, entre sus desventajas se encuentra el periodo de tiempo prolongado, la fitotoxicidad de las plantas y biodisponibilidad del metal, y el tratamiento de la biomasa contaminada cuyas alternativas de manejo incluyen su deposición en vertederos para desechos peligrosos o incineración para la purificación y recuperación de los metales pesados. Otra alternativa es la utilización de la biomasa como bioenergía, no obstante, existe poco conocimiento sobre las emisiones que se podrían generar durante este proceso. Entre los desafíos de la fitorremediación se encuentran la baja tasa de crecimiento de las plantas, raíces poco profundas y poca producción de biomasa, así como las plagas y enfermedades que pueden reducir la eficiencia en la remoción de los contaminantes. La fitorremediación ha tenido un gran auge en los últimos años, sin embargo, aún hay desafíos que enfrentar para lograr una fitorremediación sostenible.
... This is because plants from these areas are prone to high amounts of heavy metals, posing a risk of human contamination if ingested. [Lasat MM. 2000;Khan S. et. al., 2009]. ...
Article
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Yash Churna is a polyherbal powdered formulation which contains equal amounts of Sonamukhi (Cassia angustifolia Vahl; family: Caesalpiniaceae), Ajamo (Trachyspermum ammi Sprague; family: Apiaceae), Shatapushpa (Foeniculum vulgare Miller; family: Apiaceae), Harde (Terminalia chebula Retz.; family: Combretaceae) and Sanchal (Himalayan black salt) and is used to treat constipation, gas, blood impurity, itching, indigestion and acidity. The fundamental aspiration of this investigation is to document Yash Churna's distinctive characteristics in order to legitimize its identification, quality, and purity. The various parameters investigated included organoleptic characteristics, physicochemical parameters, physical characteristics of Churna, preliminary phytochemical, heavy metal, and microbial analysis, metabolomic tracking with gas chromatography/mass spectrometry, and high-performance thin layer chromatography assessment. The parameters established have been shown to be informative tools for assisting regulatory authorities, scientific organisations, and manufacturers in developing high-efficacy standard formulations, and they can be used as reference standards in a pharmaceutical startup's quality control/quality assurance laboratory. As a consequence of this investigation, each and every ingredient in Yash Churna might be identified. The characterisation parameters documented in this dissertation might be used as a standard benchmark for Yash Churna quality control analysis. To uphold batch-to-batch consistency, the criteria given in this study might be utilised to prepare a monograph on quality standards for Yash Churna.
... Certaines définitions de la bioremédiation séparent la phytoremédiation -l'utilisation de plantes pour décontamineret la biodégradation -comme l'utilisation uniquement de microorganismes 57 . La phytoremédiation consiste en l'utilisation de plantes et de leur biotopes associés (le plus souvent microbien) pour la décontamination d'un milieu 51,58 . Dans le cadre de la phytoremédiation, les polluants peuvent être dégradés dans la zone racinaire des plantes procédés de phytostimulation et de rhizodégradationou absorbés et transportés vers les feuilles pour d'autres mécanismes de dégradation (souvent photocatalysés). ...
Thesis
L’impact de l’Homme sur l’environnement et les écosystèmes constitue une problématique de premier plan de ce 21ème siècle. La pollution de l’air, des sols et des eaux endommage des écosystèmes déjà fortement affaiblis par les différents fléaux de l’activité humaine (réchauffement climatique, surexploitation, destruction des habitats naturels menant à la sixième extinction de masse, etc…). La pollution des eaux est particulièrement problématique à cause de la large diffusion possible des polluants et à l’importance de l’eau pour toute forme de vie. Cette pollution impacte ainsi la santé des êtres humains directement et indirectement à travers les réseaux trophiques. Ces polluants peuvent être naturellement dégradés – dégradation physique, chimique ou biologique (à travers la bioremédiation) – cependant la persistance de certains de ces contaminants nécessite une intervention humaine en vue de la restauration des écosystèmes. La bioaugmentation est une stratégie prometteuse consistant en l’introduction d’organismes exogènes (provenant d’un autre milieu) choisis pour leur capacité à dégrader spécifiquement les polluants persistants. Ces organismes exogènes peuvent être des plantes, des algues, des champignons ou encore des bactéries. Cette introduction d’organismes exogènes soulève une double question : celle d’un possible déséquilibre de l’écosystème, déjà perturbé, mais aussi de la sensibilité des organismes introduits aux conditions du milieu qui peuvent affecter leur viabilité et efficacité de dépollution. Dans ce contexte, l’utilisation de cellules encapsulées – plutôt qu’en suspension – a été rapportée dans la littérature1. Cette approche d’emprisonnement des microorganismes dans des matrices adaptées permet de limiter leur diffusion et leurs impacts potentiellement néfastes sur l’écosystème, tout en leur conférant une protection contre les conditions physico-chimiques du milieu. L’efficacité de la dépollution d’une telle approche réside dans la capacité des microorganismes à dépolluer les molécules ciblées mais aussi dans le choix de la matrice d’encapsulation. Les matériaux utilisés ainsi que la structure de la matrice jouent un rôle crucial pour permettre une dépollution par les microorganismes. L’utilisation de biopolymères comme matrice d’encapsulation a été largement étudiée dans la littérature2,3 en raison de leur cyto-comptabilité. La structure, quant à elle, est préférée macroporeuse en vue de la diffusion des polluants à travers le substrat. Dans cette thèse nous présenterons les résultats et réflexions sur l’encapsulation de bactéries dans des matrices d’alginate par la technique de congélation directionnelle, pour la biodégradation de colorants azoïques. La congélation directionnelle est une technique facile à mettre en œuvre, peu chère et applicable à une large gamme de biopolymères. Elle repose sur le contrôle de la croissance de cristaux de glace dont le négatif permet l’obtention de pores fortement anisotropes ainsi que l’encapsulation de cellules au sein des parois des matrices4. Nous avons alors étudié le contrôle de la structure macroporeuse et de la viabilité à travers différents leviers tels que la vitesse de croissance des cristaux (appelée vitesse du front de glace) et la concentration des microorganismes. La compréhension de l’évolution du microenvironnement autour des bactéries lors de leur congélation nous a aussi particulièrement intéressé. Malgré le fort potentiel de cette technique pour former des matrices cellularisées, anisotropes et macroporeuses, les nombreuses étapes de stabilisation nécessaires pour une utilisation en milieu aqueux diminuent drastiquement la viabilité des bactéries encapsulées. Afin de maximiser la viabilité de P. putida dans ces matrices d'alginate – ce qui permettrait une biodégradation plus efficace – nous avons conçu une nouvelle approche de traitement basée sur la dépression cryoscopique de la glace induite par des agents de réticulation ioniques. Cette approche [...]
... The influences of 1:1 mixed water on the metal contents of plant parts were diverse. Mechanisms involved in the movement of heavy metals along the soil-root-stem-leaf continuum comprise the uptake by roots and transportation into the root cells via transmembrane carriers for nutritional ions-the metals are further diffused into the xylem vessels and unloaded into the xylem sap, thereby reaching the aboveground parts of plants [40,51,52]. That is why most of the BAC and MIRS ratios were also found to be ≥ 1, except for Cd, which was similar to the previously reported data [45]. ...
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A formidable challenge in suburban agriculture is the sustainability of soil health following the use of wastewater for irrigation. The wastewater irrigation likely toxifies the crop plants making them unconsumable. We used a multivariate, completely randomized design in a greenhouse, comparing the phytoextraction capacities of Brassica juncea, Eruca sativa, Brassica rapa, and Brassica napus—all grown on silt loam soil irrigated with industrial wastewater, canal water, and a 1:1 mixture, during 2018. The studied Brassica plants were generally closely efficient in remediating toxic metals found in wastewater irrigated soil. Substantial differences between Brassica and Eruca plants/parts were recorded. For example, B. napus had significantly higher metal extraction or accumulation compared to E. sativa for Zn (71%), Cu (69%), Fe (78%), Mn (79%), Cd (101%), Cr (57%), Ni (92%). and Pb (49%). While the water and plant were the main predictors of metal extraction or accumulation, an interaction between the main effects substantially contributed to Cu, Mn, and Fe extractions from soil and accumulations in plants. Significant correlations between biological accumulation coefficient and biological transfer coefficient for many metals further supported the metal extraction or accumulation efficiencies as: B. napus > B. juncea > B. rapa > E. sativa. Root-stem mobility index correlation with stem-leaf mobility index indicated the metal translocation along the root-stem-leaf continuum. Therefore, we suggest that these crops may not be used for human or animal consumption when grown with industrial wastewater of toxic metal concentrations ≥ permissible limits. Rather these plants may serve as effective remediators of toxic metal-polluted soil.
... Environmental sources are responsible behind the contamination of natural herbs by toxic metals. Toxic metals are naturally occurring and widely distributed in soil, water, and air where Cd, Cr, Cu, Hg, Pb, and Zn are most common of these [31]. Anthropogenic activities are known potential contributor in producing toxic metals which are released into surrounding environment. ...
Article
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Introduction. Along with and in competition with orthodox medicines, herbal medicines have converted into a popular form of cure. While cumulative investigation reports on adverse effects by herbal drug uptake are few, systematic review along with deep insight into other relevant topics (carcinogenic and noncarcinogenic risk assessment, mechanism of toxicity, and entering toxic metal from source to herbal drug) is sporadic. Methods. Therefore, existing research and their published outputs pointing safety assessment of herbal medicines in terms of toxic metals have been reviewed systematically and information synthesized thematically while suggesting mechanism of toxicity, consequence of prolong exposure, and pathway of toxic metal from source to herbal drugs. Result and Discussion. Our study suggests that most of the herbal medicines were unsafe to consume although claimed harmless. Possible pathways regarding migration of toxic metals into herbal medicine are discussed. Conclusion. There should have appropriate screening from herb collection, and manufacturing to selling of finished herbal medicine by authority concerned is backed.
... Lead content in natural soil ranges from 10 to 50 ppm [1]. Due to biogeochemical cycling changes and imbalances from manmade activities such as use of fertilizer [2,3], manure [4], sludge disposals [5], or polluted irrigation water [6,7] result in the accumulation of lead in soil and create risks to human health and ecology [8]. Lead in soil may be in a soluble form, or found as lead inorganic compounds PbS, PbSO 4 , PbSO 4 . ...
Article
Used lead-acid battery recycling activities in Minh Khai handicraft village, Chi Dao commune, Van Lam district, Hung Yen province, Vietnam has markedly increased the lead (Pb) content in paddy soil. Reducing the mobility of lead and lead accumulation in rice plants/plain rice are major priorities to reduce the impacts of lead in paddy soil. Application of the minerals zeolite (4A and Faujasite) and bentonite (natural and modified) to lead-contaminated soil has been carried out in lab scale for three years. The results showed the efficiencies in reducing accumulated lead in rice were 58 and 56% after adding the artificial additives zeolite 4A and zeolite Faujasite, respectively. These results were better than those of modified bentonite and natural bentonite, which were only 44 and 24%, respectively. The control efficiency of Pb accumulated in rice plants between the supplemented samples of zeolite Faujasite, zeolite 4A, modified bentonite, and natural bentonite were 69, 56, 42, and 40%, respectively, compared with the control samples. The addition of minerals to the soils has also resulted in decreases of the growth and yield of the experimental rice plants compared with the control samples. In this research, 0.1 to 0.2% of zeolite Faujasite showed the best results in terms of reducing Pb content in soil as well as low effect on plant growth. This research opens up on-site pollution control solutions for lead-contaminated agricultural soils.
... Plants require not just macronutrients but also vital micronutrients to grow and complete the life cycle. Heavy metals (Co, Cu, Fe, Mn, Mo, Ni, and Zn) are needed for healthy plant growth in some soils (Lasat, 2000) and these can be added to the soil or applied to the leaves as a foliar spray. Cereal crops growing on Cu-deficient soils are periodically treated with Cu as a soil amendment while cereal and root crops can also be given Mn. ...
Chapter
Nutrient recycling from soil to fauna is determined by the flora for maintaining an ideal food chain and ecological balance which is solely dependent on nutrient availability and uptake from soils in an optimum quantity after maintaining specific physiological pathways. Some soil physicochemical properties and excess availability of nonessential metals and metalloids limit the availability of essential nutrients uptake by plants though some metals and metalloids are essential for plants. Excess quantity of nonessential metals and metalloids into the food chain via plant uptake enhances threats to environment, human, and other animal’s health though plants body have own strategy to maintain homeostatic balance upon excess uptake of metals and metalloids for their perpetuation. There are several sources of metals and metalloids including parent materials (lithogenic source) and anthropogenic sources (industries) responsible for affecting both agricultural and urban soils. Though excess metals and metalloids can reduce the function, occurrence, and diversity of some microorganisms as well as impede organic matter decomposition and mineralization of nutrients, microorganisms can play a satisfactory role in reducing phytotoxicity by applying several remediation strategies. On the other hand, changes in structures (installation of ETP-effluent treatment plant), incorporation of strict regulation scanner for industries, and particularly phytoremediation strategies have positive results for reducing metals and metalloids sequestration in soils. However, plants face oxidative stress or even the death penalty when grown in metals and metalloids contaminated soils. There are proven phytoremediation properties of (>400 hyperaccumulator) plant species and those should be exploited for developing phytoremediation-based sustainable mitigation strategies against metals and metalloids polluted soils. The chapter highlights the microorganisms and phytoremediation based mitigation strategies of plants against metals and metalloids polluted soils.
... A plant needs some macro and micro elements to grow and complete the lifecycle. Some soils are insufficient in the metals and metalloids (Lasat, 1999). Plants need in higher amount of nitrogen, potassium and phosphorus for their proper growth and development and thus majority of fertilizers focused on NPK based compositions. ...
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Increasing population growth has led to the issue of food scarcity which in turn adversely affects the economic development of any nation especially developing countries. This has also intermittent the landman ratio. To fulfill the need for a high population demand for food produces increased, organic and inorganic fertilizer amendments came into existence. Inorganic fertilizer amendments exhibit fast nutrient availability but incorrect use of this brought imbalance that will obstruct the availability of other nutrients and acidity of soil and eventually low productivity. However, organic amendments are slow in their result or activity, so nutrient immobilization can be seen before mineralization. Agricultural produce can face starvation at an early stage but organic fertilizer amendment is very good for a long time and free from any toxicity. The main source of contamination of agriculture is due to wastewater. Other activities like, Industrialization, transportation, urbanization, and other developmental are contaminating air, water, and soil by the release of many metals and metalloids in form of a toxic complex. So, deposition of these toxic metals and metalloids in the agro-environment has emerged as a new unpreventable source of transboundary contamination of nutrients and toxic metals and metalloids are getting settled at different surfaces mainly on agricultural produce. The toxicity of metals and metalloids is very severe even they are in very small doses. So this chapter will tell you the sources of toxic metals and metalloids as well as their mechanism of absorption by plants from soil and their impact on different domains especially on plants hindrance with sustainability goals of agriculture and future perspective and recommendations. Also, this chapter shares out the remedial aspects of these metals and metalloids contaminants done through microbes and plants.
... It causes chronic cardio-respiratory problems [3]. Bauxite and heavy metals in river sediments can be taken up by aquatic animals or plants, affecting different food chain levels [7]. Cause soil pollution by affecting the fertile topsoil, and even the restoration methods could not reverse barren soil to its original fertile status [2]. ...
... Its progressive use is deterred by lack of understanding of the complex interactions in the rhizosphere of plants during metal translocation and accumulation. The existence of plant metal hyper-accumulators capable of accumulating metals, shows that some plants are potential remedies to contaminated soils [16].Despite being energy intensive and expensive, the potential for this technology is high in the tropics due to the prevailing climatic conditions which favor plant growth and microbial activities [17,18,19], therefore, there is need to explore alternatives or support methods such as the use of mathematical models that simulate the process mechanisms with the possibility of optimizing plant use for lesser cost implications [20]. In addition, the removal of heavy metals from soils/environs should be a priority to the environmental scientist since they are not easily degraded [21,22]. ...
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Systems of ODEs were used to simulate the xylem and phloem transport kinetics of heavy metals in a phytoremediation process. Experimental data from scholarly works were used to validate the models. Analytical solutions of the models gave accuracies of between 99.79% and 99.91% for the 2 nd order pseudo model while the 1 st order pseudo model did not apply. The transportation of contaminants through the xylem tissue shows that there is a general decrease in concentration up the plant with time while the transport of heavy metals through the phloem shows an increase or a free-fall profile mechanism. The implication is that if transportation of contaminants in the phloem tissue continues at longer times, the sigmoidal profile may set in since it is a natural process. Results from optimization revealed that in 88.2 days, 25.24mg of lead (Pb) was taken up from the soil by the plant hyper-accumulator while in 1200days (3.3yrs), 65.3735gm of cadmium with an initial concentration of 100g was taken up from the soil. This shows that the model is a good predictive tool for determining the chunk weights of heavy metals removed in a phytoremediation process.
... Heavy metals are naturally found as inorganic, metallic, chemical elements that are distinguished by higher density or specific gravity (>5.0 g cm 3 ) concurrently due to higher molecular mass (atomic number above 20) (Mitchell, 1964;Lasat, 2000). "Metal" possesses the property of forming metallic cations in aqueous solution and are soluble in oxides forms in acids. ...
Chapter
The surroundings and agro ecological system has now been badly affected by heavy metal contamination and has become a threat to human and animal health. These heavy metals are nonbiodegradable and are hazardous to plant above the critical limit. Human activities like agricultural waste disposal and dumping of industrial waste, plasma incineration, and improper effluent treatment are responsible for toxicity in plants that affect the food chain. Phytoremediation techniques are utilized to remove toxic metal by using various metal-accumulator plants like Brassica sp like Brassica juncea. Phytoremediation is advanced and cheap technology through which these heavy metals can be removed from the soil. In Addition, to these techniques, organic substances, natural occurring chelators, soil reclamation process using natural compounds, suitable cropping pattern, intercropping system, and organic fertilizer application can increase the phytoremediation activity. Growing Brassica juncea with these agriculture practices can increase the capacity to uptake and remove toxic metal under polluted soils.
... Cd was assigned to be the highest weighting factor because Cd can cause severe problems due to its high mammalian toxicity and bioavailability (Saha et al., 2010). On the other hand, Ni and Zn were given lower weighting factors because Ni and Zn have low or moderate mammalian toxicity and phytotoxicity potential (Lasat, 1999). The CI is given by Eq. (2), and all detailed indexations have been previously reported (Saha et al., 2010). ...
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The recovery and reuse strategy of cyanobacterial microalgal sludge (CyanoMS) is a novel sustainable platform that can mitigate cyanobacterial harmful algal blooms (CyanoHABs) in the freshwater system. This study aimed to assess the nutritional feasibility of harvested CyanoMS for microalgal soil ameliorants (MSAs) as efficient biofertilizers by the composting process. Most MSAs exhibited stable nutrient levels during the sequential metabolic phases for the entire period. The qualitative value of all MSAs using CyanoMS as a biofertilizer was verified by the excellent Fertility Index (FI), Clean Index (CI), and plant growth values. Also, successfully matured MSAs provided long-term support for retarded release of nutrients along the microbial transitional pathway. However, suitable CyanoMS contents of 11.7–37.6% (w/w) in MSAs were critical for efficient microbial activation and substrate inhibition. Since these results were fundamentally based on microbial transition on the CyanoMS content, optimum weight content and composting period were required. Nevertheless, MSAs was commercially applicable to high value-added crops due to its high fertilization potential and recyclable value.
... Dua sifat penyerapan ion oleh tumbuhan adalah: 1) faktor konsentrasi; kemampuan tumbuhan dalam mengakumulasi ion sampai tingkat konsentrasi tertentu, bahkan dapat mencapai beberapa tingkat lebih besar dari konsentrasi ion di dalam mediumnya, 2) perbedaan kuantitatif akan kebutuhan hara yang berbeda pada tiap jenis tumbuhan. Serta perbaikan kualitas lahan tercemar logam berat menggunakan tumbuhan hiperakumulator merupakan metode perlakuan yang paling murah dibandingkan perlakuan lain [4]. ...
... An important biological feature of Silphium Perfoliatum L. is its ability to absorb pollutants and heavy metals from the soil (Burt et al., 2004;Eissa et al., 2004;Vysotskaya, 2021.) The danger of accumulation of the studied elements in the soil environment is a negative effect on environmental, physicochemical, biological functions, complex degradation of soil (Cho-Ruk et al., 2006;Lasat, 2000;Faruqui et al., 2004). Restoration of contaminated and chemically degraded soils is one of the most urgent problems today. ...
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αThe article presents the results of research on the effectiveness of the use of crops of Silphium Perfoliatum L. for phytoremediation of soils in oil-contaminated areas. Silphium Perfoliatum L. is characterized by unique opportunities for productivity and longevity, can be cultivated in one place for many years. The aim of our work was investigating the rate of accumulation of heavy metals in the aboveground and root mass of Silphium Perfoliatum L. during the introduction of sewage sludge in oil-contaminated areas. The research was conducted in the Precarpathians of Ukraine in Ivano-Frankivsk region. The experimental field is slightly sod-podzolic sandy, there are several remnants of oil spills, the so-called oil slicks. The experiment included 8 options of fertilizing Silphium Perfoliatum L.. In soils of contaminated areas determined content of total and mobile forms of metals and their content in the green mass and plant roots by methods according to ISO 4770.3 - GOST 4770.9, atomic adsorption methods in the lab of Ivano-Frankivsk State Institution branch “Soil Protection”. The metal translocation coefficient in the system "soil - vegetative mass" and in the system "soil - root" increases in a number: Cd → Ni→ Cot → Pb. That is, the lowest translocation coefficient is in the lead. However, the difference is that in the system "soil - root" the coefficient of translocation is higher by 2-3%, from the translocation of metals in the system "soil – vegetative mass". The coefficient of biological accumulation of heavy metals by perforated sylph increase in a number of elements: Pb → Co → Ni → Cd.
... Environmental sources are responsible behind the contamination of natural herbs by toxic metals. Toxic metals are naturally occurring and widely distributed in soil, water, and air where Cd, Cr, Cu, Hg, Pb, and Zn are most common of these [31]. Anthropogenic activities are known potential contributor in producing toxic metals which are released into surrounding environment. ...
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Introduction. Along with and in competition with orthodox medicines, herbal medicines have converted into a popular form of cure. While cumulative investigation reports on adverse effects by herbal drug uptake are few, systematic review along with deep insight into other relevant topics (carcinogenic and noncarcinogenic risk assessment, mechanism of toxicity, and entering toxic metal from source to herbal drug) is sporadic. Methods. Therefore, existing research and their published outputs pointing safety assessment of herbal medicines in terms of toxic metals have been reviewed systematically and information synthesized thematically while suggesting mechanism of toxicity, consequence of prolong exposure, and pathway of toxic metal from source to herbal drugs. Result and Discussion. Our study suggests that most of the herbal medicines were unsafe to consume although claimed harmless. Possible pathways regarding migration of toxic metals into herbal medicine are discussed. Conclusion. There should have appropriate screening from herb collection, and manufacturing to selling of finished herbal medicine by authority concerned is backed.
... The distribution of metals in some parts of the plant is the result of differences in the amount and rate of metal input, primarily by root pressure and their release into the environment, notably through the transpiration of the leaves. [39][40] Some metals are accumulated in the roots, probably because of certain physiological barriers to the transport of toxic elements in trace amounts. Those metals essential to metabolic needs are easily transported to the above-ground parts of the plant. ...
... Thus, the procedures to enhance phytoextraction ef cacy are developed in coherence with these aspects (Seth, 2012;Ali et al., 2013). In this approach, hyperaccumulator plant species play an imperative role, and members of different plant families like Asteraceae, Brassicaceae, Euphorbiaceae, Fabaceae, Scrophulariaceae, and Lamiaceae are involved (Lasat, 1999;Wuana and Okieimen, 2011). Sedum alfrediihas been described to hyperaccumulate Cd, Pb, and Zn (Yang et al., 2004;Deng et al., 2007). ...
Chapter
Heavy metals, metalloids, and radionuclides at their toxic concentrations have been reported to negatively affect the structural and physiological functioning of microorganisms, plants, and animals. These metals retain in the soil for very long and thus disturb flora and fauna of the particular area. High-cost methods like carbon adsorption, air stripping, and biosorption methods are being utilized, but the role of plants cannot be nullified because these they without posing a negative impact on our environment are aiding in remediating the heavy metal contamination. Different phytoremediation approaches are available, which are involved in the remediation of heavy metals/metalloids/radionuclides from the contaminated soil. The most extensively used phytoremediation approaches like phytodegradation, phytoextraction, phytofiltration, phytostabilization, and phytovolatilizationare used for remediation of metals/metalloids/radionuclide-contaminated soil. In this chapter, we discuss the applicability and drawbacks of phytoremediation along with the strategies for improving and modifying certain traits of plants to ascertain effective phytoremediation of heavy metals, metalloids, and radionuclides.
... Cd and Pb, for example, have no recognized physiological effects. The use of some phosphatic composts accidentally introduces Cd and other potentially toxic components to the soil, such as F, Hg, and Pb [34]. Pesticides. ...
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Food security is a major concern that requires sustained advancement both statistically and on the basis of Qualitative assessment. In recent years, antagonistic impacts of unforeseen toxins have impacted the quality of crops and have created a burden on human lives. Heavy metals (e.g., Hg, As, Pb, Cd, and Cr) can affect humans, adding to dreariness and in severe cases even death. It additionally investigates the conceivable geological routes of heavy metals in the surrounding subsystems. The top-to-the-bottom conversation is additionally offered on physiological/ atomic movement systems engaged with the take-up of metallic foreign substances inside food crops. At long last, the board procedures are proposed to recapture maintainability in soil-food subsystems. This paper reflects the contamination of the food crops with heavy metals, the way of transport of heavy metal to food crops, degree of toxicity after consumption and the strategies to maintain the problem.
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Stress in plants refers to environmental circumstances that have a negative impact on plant growth, development, or production. Stress causes changes in gene expression, cellular metabolism, growth rates, crop yields, and other plant responses. Many elements are absorbed by plants from the soil. Some of the elements that are absorbed are known as essentials since they are necessary for plants to complete their life cycle. Heavy metals such as cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) may have varying effects on plant health. Heavy metal concentrations have an influence on plant metabolite activity.Increased levels of lead (Pb) in the soil generate a number of metabolites and oxidative stress symptoms in plants, including reduced growth, shoot development, root growth, and fresh weight in eggplant (Solanum melongena L.) seed treated with 50 ppm and 500 ppm concentrations of Pb together with control. At 500 ppm concentration, the most significant decrease in seed germination % was noted. While it was discovered to be 100% under control, it drops by up to 45% in Pb. In contrast, high amounts of lead (500 ppm) lowered the fresh weight of seedlings of the Solanum melongena L. plant while showing increases in germination %, root length, and shoot length. As the concentration of lead increases it becomes more toxic so that plant growth is reduced.
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Coronavirus disease 2019 (COVID-19) pandemic represents a massive impact on human health, causing sudden lifestyle changes, through social distancing and isolation at home, with social and economic consequences. The aim of the study was to determine both of community and gender-based distribution of perception, attitude, preventive measures, changing lifestyle regarding COVID-19 and to help the Government and policymakers to take indispensable steps. This cross-sectional survey self-administered online-based study was carried out after the declaration of strict initial lockdown enforced in Bangladesh. The study was conducted in Rajshahi district from 30 March 2020 to 31 August 2020, a very critical time of mental suffering and lockdown. A total of 651 respondents from Rajshahi district in Bangladesh participated in the survey, and by a self-administered questionnaire, designed in the language of English. Among the collected responses, 535 were considered for the analysis, which largely belonged to Rajshahi’s middle to upper socio-economic status (SES). The data analysis was performed using Microsoft Excel 2019 and SPSS version 25.0 (Chicago, IL, USA). The data were analyzed by using descriptive statistic, chi-square test and z-proportional test. In this empirical study, 278 males and 257 females participated. More than one-tenth of males and 35% of females were not conscious of the type of Coronavirus. A lot of misperception about the incubation period of COVID-19 existed among participants. The research observed that 34.2%, of males and 25.3% of the female study population had no opinion about the treatment of COVID-19 and 27.3% of males and 21.8% of females gave a verdict that COVID-19 had no available treatment. The study discovered more surprisingly that females (67.3%), greater than males (65.5%) did not want to stay at home during the lockdown. Positively 87.8% of males and 70.4% of females washed their hands with soap or used sanitizer after coming back from outside. The consumption of a balanced diet increased by males and females was 13.3% and 6.7% respectively. Z-proportional test showed that regarding COVID-19, there were significant difference between male and female’s conception and precaution (p<0.0001). The study has used the first-time data based on the population’s lifestyle and eating habits during the COVID-19 lockdown, which will give assistance to the policy makers to develop the situation. J Bio-Sci. 30(1): 33-48, 2022 (June)
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Heavy metals are found naturally in the topsoil and are exploited for various industrial and economic activities such as sludges, emission and wastewater. Among these heavy metals, some have direct and indirect impact on the human body and agriculture. Some of these heavy metals such as copper, cobalt, iron, nickel, magnesium, molybdenum, chromium, selenium, manganese, lead and zinc have functional roles which are essential for various diverse physiological and biochemical activities in the human body and agricultural soil. However, some of these heavy metals when we get beyond tolerable limit are harmful to the communities at the prescribe level. Mainly cadmium, mercury, lead, chromium, silver, and arsenic in minute quantities causing acute and chronic toxicities in humans and environment. The main objective of the study is to describe the various mechanism of intoxication of some selected heavy metals in humans along with their health effects and arable land. Therefore, the study is to highlight on biochemical mechanisms of heavy metal intoxication which involves binding to proteins and enzymes, altering their activity and causing damage of livelihood. Moreover, the mechanism by which heavy metals cause neurotoxicity, generate free radical which promotes oxidative stress damaging lipids, proteins and DNA molecules and how these free radicals propagate carcinogenesis are discussed. Alongside these mechanisms, the noxious health effects of these heavy metals are discussed mainly human body. Soil pollution is a very vital issue all over the world because of lowering productivity loss 7% only for soil salinity among others, heavy metals and metalloids contamination viz, lead (Pb), Cadmium (Cd), Zinc (Zn), chromium (Cr) etc. is another burning issue of the present days which are come from industrial sludges, sewerage and ground water arsenic pollution. The aforesaid pollutants are not only posing arable land but also water bodies in the river band of Turag, Bhuriganga, Balu, Shitalakha, Meghna, Jamuna, Halda and other branches of rivers and beels, hoars, lakes cause destroying ecosystem even extinct of indigenous species of animals, plants and aquatics. On the other side, coastal belt is polluted by saline water both are hampering productivity other than saline tolerant plants. Introduction :
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This study evaluates the performance of commercial reverse osmosis (RO) and nanofiltration (NF) membranes for the removal of metal ions from synthetic water and surface water carried from the north-west of Lake Tanganyika in the city of Uvira, in the east of the Democratic Republic of Congo. Metal ion analyses were performed by the standardized ICP-MS and ICP-OES methods. The RO membrane showed higher metal ion rejection in high-concentration solutions (synthetic samples) prepared in the laboratory as well as in low-concentration samples from real raw water collected near Lake Tanganyika. Rejection levels were higher than 98% for Cr3+, Pb2+, Cd2+, As3+, Ni2+, and Sb+3 ions in the synthetic solutions, and 99.2, 98.8, 98.6, 99.2, 98.4, and 98.8%, respectively, in the real samples. The concentrations of metals in the permeate varied depending on the feed concentration and were 0.15 to 1.02 mg/L, 0.33 to 22 mg/L, and 0.11 to 22 mg/L in RO, NF90, and NF270 membranes, respectively. Regarding the NF membranes, the rejection of Cr, Ni, and Cd ions was interesting: 98.2, 97.8, and 92.3%, respectively. However, it was lower for Pb, As, and Sb ions: 76.9, 52.5 and 64.1%, respectively. The flux of NF was 329 to 375 L/m2.h, much higher than for RO membranes, which had a flux of 98 to 132 L/m2.h. The studied membranes are thus a feasible solution to remove the studied metals from real water sources at low concentrations since they meet the standards of the World Health Organization on specific values assigned to chemicals from industrial sources and human habitation areas where these ions are present in drinking water.
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Ledulu Lake is one of the lakes in the Rote Ndao Region. Lake Ledulu was formed in the Quaternary period with Cenozoic constituents and Neogene deposits based on geological formations. The formations found in the Lake area are sediment, chemical, limestone. The purpose of this study was to measure the metal content in the lake water and its absorption by aquatic vegetation in the ecosystem of Ledulu lake, using Instrumental neutron activation analysis (INAA) technique. NAA is one of the modern methods that is able to measure the level of heavy metal uptake in aquatic biota (water animals and aquatic plants). The metal content in the water of the lake (mg/L) is: Bromine 405.06, Calcium 7,195.66, Cerium 9.10, Cobalt 2.43, Chromium 45.90, Lanthanum 12.07, Magnesium 1,189.93, Sodium 24,382.31. Aquatic plants that absorb heavy metals in lake Ledulu are Panicum sp, Ludwigia adscendens (L.) H.Hara, Ottelia alismoides (L) pers, Najas sp, Ipomea aquatica Forssk, Pontederia korsakowii (Regel & Maack) M.Pell. & C.N.Horn, Callitriche sp, Bacopa monnierii, and Nymphaea alba L. Sodium is not absorbed by Panicum sp, Ludwigia adsendence (L), and Nymphaea alba. Lanthanum is only absorbed by Panicum sp and Callitriche sp. All other elements can be absorbed by aquatic plants in the Ledulu lake ecosystem with different absorption concentrations.
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Five submerged hydrophytes flourished in north east Nile Delta have been chosen to be the subject of this study. These are Ceratophyllum demersum, Myriophullum spicatum, Potamogeton crispus, P. nodosus and P. pectinatus .They were growing at three different hydric habitats (kafr Demira irrigating canal, El Gammalia with agricultural chemicals and contaminants and Manzala Lake with both organic and inorganic pollutants. The objective of this study are: a) providing quantitative estimates about the environmental conditions (both physical and chemical characteristics of the bottom sediments and overlying water) and the floristic characters of the hydropytic and wet canal bank vegetation at the five habitats .b) descriptions of the morphology and anatomy of the studied species) estimation of heavy metals accumulation and release of these menials from living and dead plant samples. d) investigation of the primary metabolic products of the plants, and e) elucidate the physiological aspects of the studied species including: the chlorophyll content, number and size of starch grains in the chloroplasts, membrane stability index, relative water content in the leaves, seasonal changes in heavy metals concentration in both roots and shoots as well as the seasonal change in the bioconcentrations factor.
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This book integrates knowledge about innovative technologies developed in the past decade with information about commercial-scale processes. It is written with the objective to help readers to understand the potential of achieving sustainability and high efficiency in wastewater treatment. The book presents nine chapters. Chapter 1 details the types of wastewater, its characteristics, and the major commercial-scale strategies employed to treat wastewater. Chapter 2 details the different types of physicochemical methods utilized for the remediation of heavy metals, dyes, and xenobiotics. Chapters 3 and 4 highlight innovations in the advanced oxidation process and adsorption for remediation of such complex molecules, respectively. Chapters 5, 6, and 7 highlight the recent innovations in bioremediation of xenobiotics, heavy metals, and dyes, respectively. Finally, chapters 8 and 9 discuss the latest technologies, prevailing bottlenecks, and the path ahead towards commercial viability and environmental sustainability in both physico-chemical and biological treatment processes.
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Environmental pollution by inorganic and organic chemicals in soil, water, and air is a global problem, with several deleterious effects. These chemicals find their way into plant foods and agricultural crops via absorption and uptake from the environment. Ingestion of such contaminated food sources by animals and humans may lead to various toxicological implications. In this chapter, the potential sources for contamination of soil, water, and air by organic and inorganic chemicals—including heavy metals, pesticides, plastics, antimicrobials, and other industrial chemicals—are reported. Furthermore, recent publications screening the occurrence of these chemicals in the environment are reviewed. Suggested preventive measures and remediation approaches toward such chemicals are discussed. Some reports describing uptake of the chemicals by plant foods and agricultural crops are also reviewed. Finally, potential human health risks associated with consumption of foods contaminated by inorganic and organic chemicals are further outlined.
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Soil contamination by organic and inorganic compounds is a universal concern nowadays. One such contamination is heavy metal exposure to the soil from different sources. The discharge of effluents from various factories in Punjab like tanning industries, leather industries, and electroplating industries generate a large volume of industrial effluents. These industrial units discharge their effluents directly or through the sewer into a water tributary (Buddha Nallah) and this water is being used for irrigating the crops. The heavy metals enter into the food chain thus contaminating all resources i.e. air, soil, food, and water. Preventive and remedial measures should be taken to reduce the effects of heavy metals from soil and plants. Organic soil amendments like FYM, Vermicomposting, Biochar, and poultry manure have been used to deactivate heavy metals by changing their forms from highly bioavailable forms to the much less bioavailable forms associated with organic matter (OM), metal oxides, or carbonates. These amendments have significant immobilizing effects on heavy metals because of the presence of humic acids which bind with a wide variety of metal(loid)s including Cd, Cr, Cu, and Pb.
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O objetivo desse trabalho foi avaliar o desempenho da espécie Portulaca oleracea L., conhecida popularmente como Beldroega, como hiperacumuladora de metais pesados, verificando ainda a possibilidade de usá-la como uma das técnicas de remediação, principalmente a fitoremediacão.
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Introduction- According to the World Health Organisation, 80% of the world population relies on plant material based herbal medicines for primary health care. Nine herbal products used in Ayurvedic medicine were studied for heavy metal content and assessed for their health risks. Methods- Nine herbal plant products Tagar (Valeriana jatamansi),Arjun (Terminalia arjuna), Guggulu (Commiphora wightii), Pushkarmoola (Inula racemosa), Shilajeet (Asphaltum punjabianum), Shallaki (Boswellia serrata), Haritaki (Terminalia chebula), Neem (Azadirachta indica), and Bahera (Terminalia bellirica), were collected from the local market and analyzed for heavy metals (Cd, Pb, Zn, Ni, Fe, Cu, Mn, Cr) using Atomic Absorption Spectrophotometer. The risk assessment of heavy metals in Ayurvedic herbal products in terms of the Average Daily Dose was calculated to assess the long-term consumption risk of the medicine, the estimated daily intake (EDI) was determined and the health risk due to the consumption of herbal medicine is described in term of target hazard quotient (THQ). The health risk of each herbal medicine due to the cumulative effect of the heavy metals was assessed in terms of hazard index (HI). Result- All the Ayurvedic products tested contained heavy metals, in low quantities. Chromium was below the detectable limit. Discussions and conclusions- In terms of standards given by various agencies for heavy metals dietary intake the studied Ayurvedic products when consumed in the recommended dose were found to contain heavy metals within the standard limits and pose insignificant health risks (HI= >1). The essentiality of certain heavy metals at low and ultra-low concentrations, for proper growth and physiological functioning in animals, is discussed. The study concludes that the human uptakes of heavy metals through the recommended medicinal dose of the studied Ayurvedic plant products are within the safe limits recommended by various agencies and pose a minimal health risk in short term as well as in long term consumption.
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Heavy metal contamination demands remediation using appropriate cost‐effective methods to eliminate the contaminants or convert them into lesser toxic forms to avert the potential hazards arising from such contaminations. Certain plants have a high potential for accumulating metals and phytotechnologies that can make use of such potentials, thereby offering a nature‐based and cost‐effective solution for remediation of contaminated soil. Phytotechnology such as phytomining also offers prospective means for cost‐effective recovery or beneficiation of metals. Such technologies draw on the natural processes in the rhizosphere and physiological and metabolic mechanisms in plants that regulate the chemical dynamics of such contaminants. They attempt to exploit plants'capabilities to remove, reduce, sequester, immobilize, detoxify, or degrade the pollutants. Thus, phytotechnologies and their scientific, technological, and operational advantages are an appropriate basket of nature‐based solutions for ameliorating contamination in soil systems. However, hurdles are many to be addressed for their wider success, such as low understanding of the biological mechanisms, soil properties, even the prevalent terminology‐related issues, concepts, and operationalization strategies. It is apparent that, for the wider and successful application of these technologies, scientific improvements are obligatory together with changes at policy and regulatory levels. This chapter highlights the need for amalgamation of such technologies for wider use. Here, we review different phytotechnologies and their underlying biological mechanisms to bring out the potentials of the technology as economically viable and ecologically amending. The review also highlights future research, imperative to develop these technologies coherently and effectively. The need for changes in regulatory provisions, improvement in knowledge gaps in soil chemistry, microbial and plant physiology, and transfer of phytotechnologies to the commercial sector are also discussed in this chapter. With new developments in interdisciplinary research, knowledge base, legal frameworks, and social aspects, phytotechnologies will prove to be effective in decontaminating the environment from metal contamination in a long‐run.
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Phytoremediation is a set of technologies that reduce, in situ or ex situ, the concentration of various compounds through biochemical processes carried out by plants. Phytoremediation uses plants to remove, reduce, transform, mineralize, degrade, volatilize, or stabilize contaminants present in soil, water, and air. Plants to be used for phytoremediation are selected primarily for their physiological characteristics, such as presence of specific enzymes, tolerance and assimilation of toxic substances, plant growth rates, root depth, and ability to bioaccumulate and/or degrade contaminants. A wide diversity of species has been utilized in phytoremediation. Some of these are known as hyperaccumulators, due to their high capacity to accumulate heavy metals. Phytoremediation offers several advantages, among which are the following: (i) it constitutes a sustainable technology, (ii) it is carried out without the need to transport the contaminated substrate (thus decreasing the dissemination of contaminants through air or water), (iii) it is a set of technologies that are efficiently applied to both organic and inorganic contaminants, and (iv) its cost-effectiveness is driven by conventional agronomic practices, i.e., specialized personnel and energy are not required. The benefits of the practice are also associated with the following: (v) it is minimally harmful to the environment, (vi) it improves the physical and chemical properties of the soil due to the formation of vegetation cover, (vii) it has a high probability of being accepted by the public as the plants involved are often pleasing to the eye, (viii) it does not involve excavation work and heavy traffic, and (ix) it can be employed in water, soil, air, and sediments and allows for the recycling of resources (e.g., water, biomass, metals). Therefore, this chapter aims to (a) select the main medicinal plants with the potential to phytoremediate soils contaminated by heavy metals (e.g., uranium, copper, nickel, cobalt, mercury, cadmium, lead, chromium, zinc, selenium, aluminum, iron, and manganese), (b) report on the tolerance mechanisms of phytoremediation, and (c) indicate the concentration and accumulation levels of toxic heavy metals in medicinal plants.
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It is of great significance to explore the remediation pattern in actual heavy metal (HM) contaminated sites. The field trial was carried out to research the remediation effect of biochar near a lead-zinc smelter in Feng County, China, under the rotation condition of different crops. This kind of cultivation mode is very representative in northern of China. And the pattern of production and restoration is suitable for scarce land resources and large food demand in China. The changes of soil physiochemical properties with the biochar addition, crop growth and the accumulated HMs by crops were focused on. The results showed the biochar application was excellent in improving soil nutrient elements and crop growth. The contents of TK were more obvious than those of TN and TP, with an increase of 2.6%–28.2% compared with the controls (without the addition of biochar). The yield of first season crops, i.e., soybean and corn, increased by 30%–42% and 34%–61%, respectively, and the second season crops, i.e., rape and wheat, with the increment of 25%–41% and 9%–29%, respectively. The availability forms of Cd and Pb decreased by 1.07–10.0% and 2.92–8.35%, respectively. While the improvement on the status of the HMs accumulated by crops was disappointing. The contents of HMs accumulated by crops increased to varying degrees (e.g., Pb and Zn in root, Cu and Pb in grain, and Cd in stems and leaves). Moreover, the concentrations of HMs in seeds of crops were higher than the limited levels given by the Chinese directive. Considering the results of the study and food safety, it is suggested to change the nature of the land around the smelter into woodland or construction land to prohibit the cultivation of food crops in this area.
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Plastic waste has become a major problem in the world because there are no effective strategies for its management and it ends up accumulating in the environment. In literature, attempts have been made to introduce human awareness of the use, reduction and reuse of plastic products, accompanied by traditional waste management techniques, but the problem of pollution from synthetic plastics continues to increase. Throughout the world, the problem of plastic residues has been handled by traditional techniques such as incineration, landfill and recycling. Traditional techniques have their limitations, such as the production of greenhouse gases that increase climate change which leads to affecting the living organism in both terrestrial and marine environment. Therefore, researchers are now focusing on the development of biological technologies such as composting, phytoremediation and biodegradation using microorganisms and their enzymes. These techniques are important because they mitigate the environmental pollutants although they require a lot of time to obtain results and highly qualified personnel. Attempts have also been made to replace traditional plastic with renewable and recyclable sources, such as bioplastics. Some bacteria, algae, fungi and actinomycetes have the potential to degrade these polymers because their metabolism allows them to use them as a nutrient and carbon resource. There are also genetically modified microorganisms that acquire the ability to degrade this material, as well as other recent techniques such as nanoremediation that are very promising. In the present chapter, an attempt was made under the following lines: (i) to overview the techniques used to mitigate the plastic waste, (ii) to highlight the advantages and disadvantages of each mitigation method and (iii) to discuss the biodegradation of synthetic plastics by microorganisms as an environmentally friendly alternative for the appropriate elimination of plastic waste as well as the implementation of microbial consortia to increase the biodegradation performance at commercial level.KeywordsPlasticsRecyclingBiodegradationLandfillIncineration
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Phytoremediation is also called “botanical bioremediation” and is becoming a promising area of research, which has a tremendous effect on the decontamination of polluted soils, air, and water. Conventional remediation methods of heavy metal contaminated soils are expensive and environmentally destructive that leads to the discovery of eco-friendly and cost-effective alternate technologies. Metals with an atomic weight greater than 20, metallic density higher than 5 g cm−3, and a specific gravity greater than four are considered heavy metals. Some heavy metals are essential for plant growth (Fe, Mn, Zn, Cu, Mg, Mo, and Ni), and some metals are with unknown biological functions (Cd, Cr, Pb, Co, Ag, Se, Hg). The metal fraction in the environment is highly variable, and they are introduced into the atmosphere by both natural and anthropogenic sources. Metal hyperaccumulating plants have gained increased attention because of their potential to accumulate heavy metals, thereby decontamination of metal-polluted soil. This chapter provides information about the phytoremediation potential of various weed plants belonging to the families Amaranthaceae and Euphorbiaceae on heavy metal contaminated soil. Weeds are suitable for this purpose because of their inherent resistant capability and their non-suitability for fodder purposes. Species of Amaranthus, Alternanthera, Celosia, Achyranthes, etc. from the family Amaranthaceae and Acalypha, Phyllanthus, Euphorbia, Jatropha, etc., from the family Euphorbiaceae are proven hyperaccumulator weed plants that can be used as effective phytotemediator in heavy metal contaminated soil.
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This chapter highlights the recent advancements in the field of nanosensors for the detection of metals, namely iron, copper, arsenic, mercury, lead, platinum, palladium, and rhodium. It is a well-known fact that the processes like fuel emissions, ore extractions, improper industrial waste disposal, and contamination of water and soil resources leads to the accumulation of hazardous elements in the soil. These elements pose a threat to mankind in the form of various diseases due to intake of crops grown in such soils. Thus it is essential to upscale the production of nanosensors for on-field applications. Herein, we discuss the ideal parameters of a fertile soil and the hazardous effects of the soils contaminated with heavy metals and finally the new emerging techniques used by the researchers to develop a cutting-edge generation of nanosensors for the detection of heavy trace metals in soil.
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Before regulations for biosolids utilization were developed, some highly contaminated sewage sludges were land applied on farmers’ fields. In one case, with a soil which had been amended with a high Cd:Zn ratio sludge,making the soil calcareous did not reduce Cd uptake by lettuce as raising pH had achieved in many earlier tests.We conducted an experiment to examine metal uptake by lettuce with different treatments (2% limestone, Zn, peat, or 10% addition of a biosolids compost enriched in Fe, Mn and/or Zn)would reduce the potential for Cd uptake by Romaine lettuce from soils which had been amended with high Cd biosolids in the 1960s–1970s. An unexpected result was observed: liming two of the soils induced Zn deficiency in lettuce and raised lettuce foliar Cd concentrations. The high soil Cd appears to have interfered with Zn uptake, and foliar Zn was below the deficiency diagnostic level. Added Zn or peat+Zn prevented the Zn deficiency and greatly reduced lettuce Cd levels, while compost and Zn-amended compost were not quite as effective as the ZnSO4. No apparent effects of the added Fe and Mn oxides on lettuce Cd were observed, perhaps the oxides also adsorbed added Zn, reducing its ability to inhibit Cd uptake by lettuce.We conclude that application of excess limestone plus added Zn will reduce soil Cd risk to feed and food-chain for soils with high Cd:Zn contamination such as biosolids amended soils at St. Marys, PA.
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Phytoremediation of heavy-metal contaminated soils can be inexpensive means to remove hazardous metals from soil. Two metallophytes, Thlaspi caerulescens and a Zn-tolerant ecotype of bladder campion were compared with tomato in nutrient solution to characterize Zn and Cd uptake and tolerance. Thlaspi caerulescens showed much greater tolerance to Zn/Cd treatments than the other species, with toxicity stress only apparent at 10,000 μM Zn/200 μM Cd treatment. It was also more effective at translocating both Zn and Cd from solution shoots. The results suggest that T. caerulescens may be a candidate for the phytoremediation of Zn contaminated soils.
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To identify populations with the ability to accumulate heavy metals, approximately 300 accessions pertaining to 30 plant species were grown for 4 wk in a hydroponic media that approximated the nutrient and heavy metal composition of a soil contaminated with moderate levels of cadmium (Cd), copper (Cur, and zinc (Zn). The results indicated that several Brassica spp. exhibited moderately enhanced Zn and Cd accumulation. Selected accessions of Brassica juncea (L.) Czern, B. napus L., and B. rapa L. were then grown in pots with heavy metal-contaminated soil to compare the Zn and Cd phytoextraction by these species to that of Thlaspi caerulescens J. & C. Presl, a known Zn and Cd hyperaccumulator, and two grass species, Agrostis capillaris L. and Festuca rubra L. The three Brassica spp. were the most effective in removing Zn from the contaminated soil, primarily because they produced more than 10 times the shoot biomass produced by T. caerulescens. When the soil was amended with Gro-Power, a commercial soil amendment that improves soil structure and fertility, removal of Zn by plant shoots doubled to more than 30 000 mg Zn pot-1 (4.5 kg). The results suggest that for phytoremediation of metal-polluted soils to be successful, a strategy should be considered that combines rapid screening of plant species possessing the ability to tolerate and accumulate heavy metals with agronomic practices that enhance shoot biomass production and/or increase metal bioavailability in the rhizosphere.
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Using the noninvasive technique of X-ray absorption spectroscopy (XAS), we have been able to determine the ligand environment of Zn in different tissues of the Zn-hyperaccumulator Thlaspi caerulescens (J. & C. Presl.). The majority of intracellular Zn in roots of T. caerulescens was found to be coordinated with histidine. In the xylem sap. Zn was found to be transported mainly as the free hydrated Zn2+ cation with a smaller proportion coordinated with organic acids. In the shoots, Zn coordination occurred mainly via organic acids, with a smaller proportion present as the hydrated cation and coordinated with histidine and the cell wall. Our data suggest that histidine plays an important role in Zn homeostasis in the roots, whereas organic acids are involved in xylem transport and Zn storage in shoots.
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In this study, the role of root organic acid synthesis and exudation in the mechanism of aluminum tolerance was examined in Al-tolerant (South American 3) and Al-sensitive (Tuxpeo and South American 5) maize genotypes. In a growth solution containing 6 M Al3+, Tuxpeo and South American 5 were found to be two- and threefold more sensitive to Al than South American 3. Root organic acid content and organic acid exudation from the entire root system into the bulk solution were investigated via high-performance liquid chromatographic analysis while exudates collected separately from the root apex or a mature root region (using a dividedroot-chamber technique) were analyzed with a more-sensitive ion chromatography system. In both the Al-tolerant and Al-sensitive lines, Al treatment significantly increased the total root content of organic acids, which was likely the result of Al stress and not the cause of the observed differential Al tolerance. In the absence of Al, small amounts of citrate were exuded into the solution bathing the roots. Aluminum exposure triggered a stimulation of citrate release in the Al-tolerant but not in the Al-sensitive genotypes; this response was localized to the root apex of the Al-tolerant genotype. Additionally, Al exposure triggered the release of phosphate from the root apex of the Al-tolerant genotype. The same solution Al3+ activity that elicited the maximum difference in Al sensitivity between Al-tolerant and Al-sensitive genotypes also triggered maximal citrate release from the root apex of the Al-tolerant line. The significance of citrate as a potential detoxifier for aluminum is discussed. It is concluded that organic acid release by the root apex could be an important aspect of Al tolerance in maize.
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Most bacteria, fungi, and some plants respond to Fe stress by the induction of high-affinity Fe transport systems that utilize biosynthetic chelates called siderophores. To competitively acquire Fe, some microbes have transport systems that enable them to use other siderophore types in addition to their own. Bacteria such as Escherichia coli achieve this ability by using a combination of separate siderophore receptors and transporters, whereas other microbial species, such as Streptomyces pilosus, use a low specificity, high-affinity transport system that recognizes more than one siderophore type. By either strategy, such versatility may provide an advantage under Fe-limiting conditions; allowing use of siderophores produced at another organism’s expense, or Fe acquisition from siderophores that could otherwise sequester Fe in an unavailable form. Plants that use microbial siderophores may also be more Fe efficient by virtue of their ability to use a variety of Fe sources under different soil conditions. Results of our research examining Fe transport by oat indicate parity in plant and microbial requirements for Fe and suggest that siderophores produced by root-colonizing microbes may provide Fe to plants that can use the predominant siderophore types. In conjunction with transport mechanisms, ecological and soil chemical factors can influence the efficacy of siderophores and phytosiderophores. A model presented here attempts to incorporate these factors to predict conditions that may govern competition for Fe in the plant rhizosphere. Possibly such competition has been a factor in the evolution of broad transport capabilities for different siderophores by microorganisms and plants.
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A NUMBER of terrestrial plants accumulate large quantities of metals such as zinc, manganese, nickel, cobalt and copper in their shoots1. The largest group of these so-called 'metal hyperaccumulators' is found in the genus Alyssum, in which nickel concentrations can reach 3% of leaf dry biomass2,3. Apart from their intrinsic interest, plants exhibiting this trait could be of value in the decontamination of metal-polluted soils4-6. However, the biochemical basis of the capacity for metal accumulation has not been elucidated. Here we report that exposing hyperaccumu-lator species of Alyssum to nickel elicits a large and proportional increase in the levels of free histidine, which is shown to be coordinated with nickel in vivo. Moreover, supplying histidine to a non-accumulating species greatly increases both its nickel tolerance and capacity for nickel transport to the shoot, indicating that enhanced production of histidine is responsible for the nickel hyperaccumulation phenotype in Alyssum.
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Severe reproductive impacts were found in aquatic birds nesting on irrigation drainwater ponds in the San Joaquin Valley of California. Of 347 nests studied to late incubation or to hatching, 40.6% had at least one dead embryo and 19.6% had at least one embryo or chick with an obvious external anomaly. The deformities were often multiple and included missing or abnormal eyes, beaks, wings, legs and feet. Brain, heart, liver and skeletal anomalies were also present. Mean selenium concentrations in plants, invertebrates, and fish from the ponds were 22–175 ppm (dry weight), about 12 to 130 times those found at a nearby control area. Bird eggs (2.2–110 ppm) and livers (19–130 ppm) also contained elevated levels of selenium. Aquatic birds may experience similar problems in other areas where selenium occurs at elevated levels.
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Inorganic mercury in contaminated soils and sediments is relatively immobile, though biological and chemical processes can transform it to more toxic and bioavailable methylmercury. Methylmercury is neurotoxic to vertebrates and is biomagnified in animal tissues as if is passed from prey to predator. Traditional remediation strategies for mercury contaminated soils are expensive and site-destructive. As an alternative we propose the use of transgenic aquatic, salt marsh, and upland plants to remove available inorganic mercury and methylmercury from contaminated soils and sediments. Plants engineered with a modified bacterial mercuric reductase gene, merA, are capable of converting Hg(II) taken up by roofs to the much loss toxic Hg(O), which is volatilized from the plant Plants engineered to express the bacterial organomercurial lyase gene, merB, are capable of converting methylmercury taken up by plant roots into sulfhydryl-bound Hg(II). Plants expressing both genes are capable of converting ionic mercury and methylmercury to volatile Hg(O) which is released into an enormous global atmospheric Hg(O) pool. To assess the phytoremediation capability of plants containing the merA gene, a variety of assays were carried out with the model plants Arabidopsis thaliana, and tobacco (Nicotiana tabacum).
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With more than a decade of research behind them, technology developers are getting plants into the field to clean up metal-contaminated soil. Myrna Watanabe reports on these new companies and continuing efforts to find or breed 'hyperaccumulators'.
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Wastes may supply enough macronutrients to act as N, P, or K fertilizers and provide optimum macronutrients in forage plants. Alternatively, the waste may provide N at a C:N ratio that causes nitrogen deficiency and low protein levels. Macroelement fertility balance must be managed carefully to obtain both optimum plant growth and forage quality. Use of sewage sludge as N and P fertilizer has led to severe K deficiency unless K fertilizer is supplied. Woody wastes cause severe N deficiency unless adequate N is supplied or the wastes are composted with N fertilizer before application. Some microelements are so insoluble or strongly sorbed in soil that plant shoots do not have significantly increased concentrations of the elements even when soils are greatly enriched. These and other aspects of the subject are reviewed in the paper, which emphasizes management of land treatment sites. Refs.
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Zinc accumulation by Thlaspi cepeaefolium (Wulfen) Koch, Biscutella levigata L. and Anthyllis vulneraria L. growing on calamine soils was studied in shoots, leaves and roots at different times during one season. Measurements were made polarographically. A. vulneraria and B. levigata accumulate the highest amounts of zinc in the roots and leaves during spring: the metal is then removed and translocated to the shoots. T. cepeaefolium always shows the lowest zinc accumulation in the roots, suggesting that in this species there is no metal inactivation by root cells.
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Some plants growing on serpentine soils sequester (hyperaccumulate) nickel from those soils in their tissues. Several ecological functions for metal hyperaccumulation have been suggested, including defense against herbivores. This study tests the herbivore defense hypothesis using the Ni hyperaccumulator Thlaspi montanum var. montanum. Leaves differing 167-fold in Ni content (3,000 vs 18 ppm) were obtained by growing plants on high- and low-Ni soils. Leaves were fed to larvae of Pieris rapae, a generalist folivore. Larvae fed high-Ni leaves did not grow and suffered 100% mortality after 12 d, whereas those fed low-Ni leaves quadrupled in weight with a corresponding mortality of only 21%. Larvae fed an artificial diet containing 0, 100, 500, or 1,000 ppm Ni showed acute toxicity at 1,000 ppm. We conclude that hyperaccumulated Ni can poison folivores that feed exclusively upon Ni-hyperaccumulating species and therefore is an herbivore defense for some plants native to serpentine soils.
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Electron probe X-ray microanalysis of fracture faces of quench frozen hydrated bulk samples of Lemna minor fronds exposed to high levels of Zn (300 µM) has shown the presence of globular deposits up to 1 µm in diameter containing Zn, K and P in parenchyma cells of mature fronds, and Zn, K, Mg and P in immature parenchyma cells of daughter fronds (or turions). Although this method of direct analysis of bulk samples does not lend itself to a quantitative comparison of number and composition of globules in Zn-tolerant and Zn-sensitive clones of Lemna minor, it has the advantages of simplicity of specimen preparation, rapid detection of Zn-P-containing globules, and avoidance of diffusional artifacts. Comparisons with prepared K Mg phytate and Zn standards, and additional data obtained by X-ray microanalysis of freeze-substituted thin sections, established the elemental proportions of Zn, Mg, K and Ca relative to P, which indicate that generally up to 8 (molar ratio of Zn to phytic acid = 4) and sometimes up to 12 (molar ratio of Zn to phytic acid = 6) valencies can be occupied by Zn and up to 4 by K and/or Mg. Some of the Ca that appears to be associated with globules may result from elemental redistribution during the process of freeze-substitution especially when Ca oxalate crystals are present in neighbouring raphide cells. X-ray microanalysis provided evidence for the absence of Zn from these raphides.
Article
The activities of nicotianamine aminotransferase, one of the enzymes for the biosynthesis of mugineic acid-family phytosiderophores, were examined in six graminaceous species. The enzyme activities were induced by Fe-deficiency treatments in all species tested and had a considerable correlation to the amounts of secreted mugineic acids.
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The influence of different zinc (Zn) concentrations (1.5 to 1500 μM) on organic acid levels in roots and shoots of the Zn‐hyperaccumulator plant Thlaspi caerulescens was investigated. In shoots, malate was the most abundant organic acid (164 to 248 μmol/g f.w.), followed by citrate, succinate, and oxalate. A significant correlation between soluble Zn and both malate and oxalate was observed in shoots, but not in roots. In shoots, a significant correlation between inorganic cation equivalents and organic acid anion equivalents was found. These observations and the finding, that organic acid concentrations were high even under suboptimal Zn supply (1.5 μM) suggest that in T. caerulescens the high organic acid concentration in shoots is a constitutive property. The variation of the organic acid concentrations seem to be a consequence of the cation‐anion balance rather than a specific Zn tolerance mechanism. The constitutively high organic acid concentration may be responsible for the high Zn and iron (Fe) tissue concentrations required for optimum growth in T. caerulescens.
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summaryLead transport has been characterized in corn (Zea mays L. cv. Fiesta) and ragweed (Ambrosia artemisiifolia L.), and the Pb phytoextraction efficiency of these species has been compared with that of Tritiaim aestivum, Thlaspi rotundifolium, Thlaspi caerulescens and Brassica juncea, using both nutrient solutions and Pb-contaminated soils. Our results demonstrated that plant species differ significantly in Pb uptake and translocation. In short term (60 min) experiments, Pb uptake by ragweed roots was threefold higher than that by corn roots. After 2 wk of Pb (100/yM) exposure in hydroponics, root-Pb concentration was 24000 mg kg−1 for ragweed and 4900 mg kg−1 for corn. In contrast to root-Pb concentration, shoot-Pb concentration was significantly higher in corn (560 mg kg−1) than in ragweed (30 mg kg-1). At an external Pb concentration of 20/IM, corn concentrated Pb in shoots by 90-fold, and ragweed concentrated Pb in shoots by 20-fold over the solution Pb concentration. Of the 11 species/cultivars tested using both nutrient solutions and Pb-contaminated soils, corn accumulated the highest shoot-Pb concentration. Using this corn cultivar, we investigated the role of synthetic chelates in Pb phytoextraction. Addition of HEDTA (2.0 g kg−1 soil) to a Pb-contaminated soil (total soil Pb 2500 mg kg−1) resulted in a surge of Pb accumulation in corn. The shoot Pb-concentration was increased from 40 mg kg−1 for the control (-HEDTA) to 10600 mg kg−1 for the HEDTA-treated soil. To our knowledge, this is the highest shoot Pb concentration reported in the literature for plants grown on Pb-contaminated soils. Our results suggest that in combination with sou amendment, some agronomic crops, such as corn, might be used for the clean-up of Pb-contaminated soil.
Article
Plants known as hyperaccumulators take up and sequester high concentrations of potentially toxic elements from metalliferous soils. We tested the hypothesis that zinc hyperaccumulation benefits plants by deterring herbivory. In laboratory feeding trials, three species of herbivores were allowed to choose between Thlaspi caerulescens (Brassicaceae) plants grown in low-Zn and Zn-amended culture solution. Locusts (Schistocerca gregaria), slugs (Deroceras caruanae), and caterpillars (Pieris brassicae) all showed significant preferences for plants with lower foliar Zn concentrations. Such differential feeding could result in selection pressures favouring the evolution of hyperaccumulation. The findings are also relevant to current proposals to exploit hyperaccumulation as a means of remediating metal-contaminated soils.
Article
The uptake of manganese by barley plants grown in solution culture is stimulated in the presence of micro-organisms, irrespective of whether they originated as casual laboratory contaminants or as rhizosphere micro-organisms in the soil. The microbial effect is mediated by a watersoluble substance but neither its identity nor its mode of action has yet been established. When manganese is supplied as EDTA chelates these appear to be broken down at or near the surface of the roots and this process is accelerated in the presence of micro-organisms. Under the conditions of these experiments EDTA was absorbed by the plants much less readily than manganese.
Article
A recombinant cauliflower mosaic virus (Ca-MTII) was constructed by inserting a cDNA clone of Chinese hamster metallothionein II into the open reading frame II of the cloned virus pCa-BB1. Systemically-infected Brassica campestris tissue contained metallothionein at a level of 0.5 percent of the soluble leaf protein. This efficient expression conferred four times the Cd-binding capacity when compared with Ca-BB1 infected leaves. Ca-MTII-infected leaves exposed to 1 mM CdCl2 bound all the free Cd whereas uninfected leaves possessed 43.8 nmol free Cd per milligram of protein. This may be responible for Cd resistance in the Ca-MTII plant cells. Metallothionein is the first mammalian gene product shown to be functional in plants.
Article
Inbred lines of corn (Zea mays L.) differ in accumulation, of Zn and Cd in leaves and grain. The capacity to accumulate Zn and Cd may be under genetic control. Twenty corn inbreds were planted in replicated control and sewage sludge amended, field, lysimeter plots to obtain information on uptake of Zn and Cd in leaves and grain. Sludge treatments had significantly increased concentrations of both Zn and Cd in the plow layer of soil. Mean total concentrations of Zn ranges from 68 to 454 mg/kg and of Cd from 0.3 to 20.6 mg/kg in the surface of Blount silt loam (Aerie ochraqualf, fine illitic, mesic) soil for control and maximum sludge treated plots, respectively. Concentrations of Zn and Cd in leaves of all inbreds were significantly increased on maximum sludgetreated plots. Zinc concentrations in leaves ranged from 61.8 mg/kg in B77 to 281.8 mg/kg in Oh43 and leaf Cd ranged from 2.5 mg/kg in R805 to 62.9 mg/kg in B37. Concentrations of Zn and Cd in grain of inbreds (except H99 for Zn and H99, Oh545, and R805 for Cd) were increased by higher concentrations of sludge borne metals in soil. Concentrations of Zn in grain varied from 33.8 mg/kg for H99 to 70.0 mg/kg for A619 and Cd varied from 0.08 mg/kg for R805 to 3.87 mg/kg for B37. Inbreds accumulating relatively high levels of Zn in leaf and grain tissue did not always accumulate high concen trations of Cd or vice versa. Mechanisms for controllin absorption of Zn and Cd appeared to be independent each other. Please view the pdf by using the Full Text (PDF) link under 'View' to the left. Copyright © . .
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This report identifies individual contaminants and contaminant mixtures that have been measured in the ground at 91 waste sites at 18 US Department of Energy (DOE) facilities within the weapons complex. The inventory of chemicals and mixtures was used to identify generic chemical mixtures to be used by DOE's Subsurface Science Program in basic research on the subsurface geochemical and microbiological behavior of mixed contaminants (DOE 1990a and b). The generic mixtures contain specific radionuclides, metals, organic ligands, organic solvents, fuel hydrocarbons, and polychlorinated biphenyls (PCBs) in various binary and ternary combinations. The mixtures are representative of in-ground contaminant associations at DOE facilities that are likely to exhibit complex geochemical behavior as a result of intercontaminant reactions and/or microbiologic activity stimulated by organic substances. Use of the generic mixtures will focus research on important mixed contaminants that are likely to be long-term problems at DOE sites and that will require cleanup or remediation. The report provides information on the frequency of associations among different chemicals and compound classes at DOE waste sites that require remediation.
Article
The effect of the zinc (Zn) nutritional status on the rate of phyto‐siderophore release was studied in three wild grass species (Hordeum murinum, Agropyron orientale, and Secale cereale) grown in nutrient solution under co‐trolled environmental conditions. These wild grasses are highly “Zn‐efficient”; and grow well on severely Zn‐deficient calcareous soils in Turkey (DTPA‐extractable Zn was 0.12 mg/kg soil and CaCO3 was 37%). In all wild grasses studied, Zn deficiency reduced shoot growth but had no effect on root growth. Low amounts of phytosiderophores were released from roots of all wild grasses adequately supplied with Zn. In plants grown without Zn, release of phytosiderophores progressively increased with the onset of visual Zn deficiency symptoms, such as inhibition of shoot elongation and appearance of chlorotic and necrotic patches on leaves. Compared to Zn‐sufficient plants, phytosiderophore release increased 18–20‐fold in deficient plants. HPLC analysis of root exudates showed that the dominating phytosiderophore in Zn‐deficient Agropyron and Hordeum was 3‐epi‐hydro‐xymugineic acid (epi‐HMA) and was 3‐hydroxy‐mugineic acid (HMA) in Secale. Besides HMA, epi‐HMA and mugineic acid (MA) were also detected in exudates of Zn‐deficient Secale. The results indicate the importance of phytosiderophores in adaptation of wild grasses to Zn‐deficient calcareous soils. Phytosiderophores might enhance mobilization of Zn from sparingly soluble Zn pools and from adsorption sites, both in the rhizosphere and within the plants.
Article
The main purpose of this study is to familiarize policy and decision makers with the land treatment method of treating or 'disposing' municipal wastewater. An attempt is made to provide preliminary guidance to designers for how and where the facility can be sited in relation to the population served. The environment created was evaluated with emphasis on that environment which impacts on people living nearby. Evaluations were made of characteristics of potential areas and areas currently served, size of population served, soils, crops, health hazards, aesthetics and rate and quantity of application. Factors which affect siting are set out for the consideration of the facility designer. Four siting techniques (planning goals) were established; buffer area, isolation, natural resource preserve and farm-municipality cooperative. Land treatment is certainly a most worthy method of treating municipal wastewater from large as well as small populations where the soil and climatic conditions are favorable, and the farmers economic situation can be improved.
Article
Phytoremediation is emerging as a potential cost-effective solution for the remediation of contaminated soils. Because contaminants such as lead (Pb) have limited bioavailability in the soil, a means of solubilizing the Pb in the soil and facilitating its transport to the shoots of plants is vital to the success of phytoremediation. Indian mustard (Brassica juncea) was used to demonstrate the capability of plants to accumulate high tissue concentrations of Pb when grown in Pb-contaminated soil. Concentrations of 1.5% Pb in the shoots of B. juncea were obtained from soils containing 600 mg of Pb/kg amended with synthetic chelates such as EDTA. The accumulation of Pb in the tissue corresponded to the concentration of Pb in the soil and the concentration of EDTA added to the soil. The accumulation of Cd, Cu, Ni, and Zn from contaminated soil amended with EDTA and other synthetic chelators was also demonstrated. The research indicates that the accumulation of metal in the shoots of B. juncea can be enhanced through the application of synthetic chelates to the soil, facilitating high biomass accumulation as well as metal uptake.
Article
An analytical procedure involving sequential chemical extractions has been developed for the partitioning of particulate trace metals (Cd, Co, Cu, Nl, Pb, Zn, Fe, and Mn) into five fractions: exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter, and residual. Experimental results obtained on replicate samples of fluvial bottom sediments demonstrate that the relative standard deviation of the sequential extraction procedure is generally better than ± 10%. The accuracy, evaluated by comparing total trace metal concentrations with the sum of the five individual fractions, proved to be satisfactory. Complementary measurements were performed on the individual leachates, and on the residual sediments following each extraction, to evaluate the selectivity of the various reagents toward specific geochemical phases. An application of the proposed method to river sediments is described, and the resulting trace metal speciation is discussed.
Article
Malate, oxalate and mustard oils were analysed in zinc-resistant and zinc-sensitive ecotypes of Silene cucubalus Wib., Rumex acetosa L., Thlaspi alpestre L. and Agrostis tenuis Sibth. The effect of zinc on the activities of carbonic anhydrase and peroxidase in Siiene cucubalus was tested. Carbonic anhydrase of the zinc-resistant ecotypes was stimulated by addition in vivo of high amounts of zinc. The high activity of peroxidase in the non-zinc-resistant ecotypes after the addition of zinc documented a poisoning of the sensitive plants by zinc. The amount of oxalate differed greatly between ecotypes. There was, however, no direct correlation between zinc-resistance and oxalate. When applying zinc to the nutrient medium, the synthesis of oxalate was inhibited in zinc-sensitive, but stimulated in zinc-resistant ecotypes of Silene cucubalus and Rumex acetosa. In Thlaspi alpestre high concentrations of mustard oil glucosides were found. Zinc-resistant plants produced twice as much glucosides as sensitive ones. A possible role of mustard oils in zinc-resistance is discussed. In the content of malate there were great quantitative differences between zinc-resistant and zinc-sensitive plants. All zinc-resistant ecotypes of all the species contained much higher concentrations in their green organs than the sensitive ones. It is assumed that malate is a major factor in the evolution of zinc-resistance. Malate may act as a complexing agent for zinc within the plasma, whereas oxalate and mustard oils may function as “terminal acceptors” of large amounts of zinc. The role of malate may be extended by a special transport mechanism, by which zinc is eliminated from the plasma into the vacuole.
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Pseudomonas maltophilia strain O-2, isolated from soil at a toxic waste site in Oak Ridge, Tennessee, catalyzed the transformation and precipitation of numerous toxic metal cations and oxyanions. When a viable inoculum (1%) of O-2 was introduced into nutrient broth containing Hg(II), Cr(VI), Se(IV), Pb(II), Au(III), Cd(II), Te(IV), or Ag(I), effective removal of the toxic metal was complete within 1, 1, 2, 2, 2, 4, 5, and 7 d, respectively. The NADPH-dependent reduction of Hg(II) to Hg0 was catalyzed by an inducible mercuric reductase. The reduction of selenite and tellurite to their insoluble elemental forms appeared to be mediated by an intracellular glutathione reductase that utilized the spontaneously formed bis(glutathio)Se(II) or bis(glutathio)Te(II), respectively, as pseudosubstrates. The three-electron reduction of hexavalent chromium was catalyzed by a membrane-bound chromate reductase. The enzymatic basis for the remaining metal transformations was not immediately apparent. It is anticipated that Pseudomonas maltophilia and related organisms could eventually be exploited for the removal of toxic metal wastes from selected, heavily polluted sites.
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The effect of the zinc (Zn) nutritional status on the rate of phytosiderophore release was studied in nutrient solution over 20 days in four bread wheat (Triticum aestivum cvs. Kiraç-66, Gerek-79, Aroona and Kirkpinar) and four durum wheat (Triticum durum cvs. BDMM-19, Kunduru-1149, Kiziltan-91 and Durati) genotypes differing in Zn efficiency. Visual Zn deficiency symptoms, such as whitish-brown necrosis on leaves and reduction in plant height appeared first and more severe in Zn-inefficient durum wheat genotypes Kiziltan-91, Durati and Kunduru-1149. Compared to the bread wheat genotypes, all durum wheat genotypes were more sensitive to Zn deficiency. BDMM-19 was the least affected durum wheat genotype. Among the bread wheat genotypes, Kirkpinar was the most sensitive genotype. In all genotypes well supplied with Zn, the rate of phytosiderophore release was very low and did not exceed 1 μmol 32 plants-1 3h-1, or 0.5 μmol g-1 root dry wt 3h-1. However, under Zn deficiency, with the onset of visual Zn deficiency symptoms, the release of phytosiderophores was enhanced in bread wheat genotypes up to 7.5 μmol 32 plants-1 3h-1, or 9 μmol g-1 root dry wt 3h-1, particularly in Zn-efficient Kiraç-66, Gerek-79 and Aroona. In contrast to bread wheat genotypes, phytosiderophore release in Zn-deficient durum wheat genotypes remained at a very low rate. Among the durum wheat genotypes BDMM-19 had highest rate of phytosiderophore release. HPLC analysis of root exudates showed that 2′-deoxymugineic acid (DMA) is the dominating phytosiderophore released from roots of Zn-efficient genotypes. In root extracts concentration of DMA was also much higher in Zn-efficient than in inefficient genotypes. The results demonstrate that enhanced synthesis and release of phytosiderophores at deficient Zn supply is involved in Zn efficiency in wheat genotypes. It is suggested that the expression of Zn efficiency mechanism is causally related to phytosiderophore-mediated enhanced mobilization of Zn from sparingly soluble Zn pools and from adsorption sites, both in the rhizosphere and plants.