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Accumulation of heavy metals in four grasses grown on lead and zinc mine tailings
Abstract
A field experiment was conducted to compare the growth and metal accumulation of Vetiveria zizanioides, Paspalum notatum, Cynodon dactylon and Imperata cylindraca var. major on the tailings, amended with 10 cm domestic refuse + complex NPK fertilizer(Treatment A), 10 cm domestic refuse(Treatment B) and complex NPK fertilizer (Treatment C) respectively, and without any amendment used as control (Treatment D). The results indicated that V. zizanioides was a typical heavy metal excluder, because the concentrations in shoots of the plants were the lowest among the four plants tested. The most of metal accumulated in V. zizanioides distributed in its root, and transportation of metal in this plant from root to shoot was restricted. Therefore, V. zizanioides was more suitable for phytostabilization of toxic mined lands than P. notatum and C. dactylon, which accumulated a relatively high level of metals in their shoots and roots. It was also found that I. cylindraca var. major accumulated lower amounts of Pb, Zn and Cu than C. dactylon and P. notatum, and could also be considered for phytostalilisaton of tailings. Although the metal(Pb, Zn and Cu) concentrations in shoots and roots of V. zizanioides were the lowest, the total amounts of heavy metals accumulated in shoots of V. zizanioides were the highest among the four tested plants due to the highest dry weight yield of it. The results indicated that V. zizanioides was the best choice among the four species used for phytoremediation (for both phytostabilization and phytoextraction) of metal contaminated soils.
... Its biomass is extremely high under tropical hot and wet conditions, producing more than 100 tons of dry matter ha −1 year −1 (Truong 2003). In sub-tropical weather, vetiver can produce high dry biomass from 10 to 20 tons after 5-6 months of cultivation Shu et al. 2004). This may be due to the fact that vetiver retains high activity of the key enzymes involved in photosynthesis (NADP-MDH and NADP-MET) even when cultivated in temperate climates (Bertea and Camusso 2002) (Figure 12.1). ...
... mg kg −1 , respectively (Chiu et al. 2006;Wilde et al. 2005). Under field conditions, vetiver could grow on mine tailing soils containing total Pb, Zn, Cu and Cd of 2078-4164, 2472-4377, 35-174 and 7-32 mg kg −1 , respectively (Shu et al. 2002;Yang et al. 2003;Shu et al. 2004;Zhuang et al. 2005). The survival rates, growth and biomass of vetiver cultivated on heavy metal-contaminated soil can be greatly improved by addition of organic matter (domestic refuse and sewage sludge), inorganic fertilizer and, especially, the combination of organic matter and inorganic fertilizer (Chiu et al. 2006;Wilde et al. 2005;Yang et al. 2003;Shu et al. 2002). ...
... To improve Zn bioavailability in the soils, and hence Zn accumulation in vetiver grass, the application of chelating agents is an effective approach. Nitrilotriacetic acid (NTA) was one of the most Shu et al. (2004) effective chelating agents to increase the water solubility of Zn in the soils, and therefore the amount of Zn accumulated in vetiver biomass (Chiu et al. 2006). The concentration of the extractable Zn in the soils rapidly increased with the rate of applied NTA, particularly at the rate of 10 and 20 mmol kg −1 . ...
... It forms a vegetative cover to prevent soil erosion and contamination of distant areas. Other reports reveal the ability of the grasses C. dactylon, Paspalum notatum, and Imperata cylindrica to stabilize Pb/ Zn mine tailings (Shu et al. 2004). Similar results were observed in Piptatherum miliaceum exposed to Pb and Zn, showing hyperaccumulation of Pb and efficient extraction of Zn from mine tailings (García et al. 2004). ...
... This mechanism takes place either by the natural physiological ability of the plants, which is termed as continuous phytoextraction, or by induced phytoextraction by the artificial addition of chelating agents such as ethylene diamine tetraacetate (EDTA) (Andra et al. 2009a), ethylenediamine disuccinate (EDDS) (Andra et al. 2011), and other organic amendments (Shutcha et al. 2010). Phytoextraction of Pb, Zn, and Cd mine wastes is performed by V. zizanioides (Chantachon et al. 2004;Chen et al. 2012b;Roongtanakiat and Sanoh 2011;Shu et al. 2004;Wilde et al. 2005), F. arundinacea, and L. perenne (Pricop et al. 2010); Ni by P. pratensis and F. arundinacea (Bosiacki and Zielezińki 2011); Cd and Zn by Eleusine indica (Garba et al. 2013) and Zn by H. vulgare (Ebbs and Kochian 1998) and Lygeum spartum (Conesa et al. 2007); and Pb and Zn by the natural colonizers of mine tailings C. intybus and C. dactylon (Del Rio-Celestino et al. 2006). ...
Phytoremediation is an established technique for amelioration of soil contaminated with complex mixtures of heavy metals of anthropogenic origin. Coal fly ash and mine tailings include a conglomerate of heavy metals such as Cr, Pb, Hg, As, Ni, Cd, Cu, Mn, and Fe depending on the source of coal/ore and cause large-scale ecotoxicity. Unreclaimed mine tailing sites and coal fly ash dumpsites are a worldwide problem, presenting a source of contamination for nearby communities. The disposal sites are subject to erosion and are major causes of air pollution. Phytoremediation using plants for in situ stabilization and immobilization of these heavy metal-contaminated sites has gained momentum in the past few decades due to its cost-effectiveness and environmental sustainability. In this regard, the use of grasses is of prime importance due to their rapid growth, large biomass, resistance to phytotoxicity, and genotoxicity by heavy metals as compared to herbs, shrubs, and trees. Phytostabilization by the compact root system of grasses retards the formation, mobility, and bioavailability of hazardous leachates by high uptake and accumulation of the complex mixtures of heavy metals within them. Such grasses prevent natural succession by weeds and other plants leading to safe grazing by animals. Among the members of Poaceae, aromatic grasses are economically important plants due to their essential oil production. They rank higher than edible grasses, which are susceptible to heavy metal contamination in their edible parts. Various biochemical and molecular mechanisms govern the ADME (absorption, distribution, metabolism, excretion) of heavy metal contaminants in grasses growing in mine tailings and fly ash dumpsites. Metal-binding phytochelatins, metallothioneins, and antioxidant enzymes have key functions in these mechanisms. This chapter encompasses the role of members of Poaceae and aromatic grasses in phytoremediation of mine soil and coal fly ash with emphasis on their biochemical and molecular mechanisms.
... Así, por ejemplo, los jales mineros provenientes de los estados de Zacatecas y Guerrero contienen alrededor de 8466 ± 116 mg de Pb/kg y 12475 ± 324 mg de Zn/kg (Flores de la Torre et al.,2018); y 10.844 mg/kg As, 4781 mg/kg Pb, 3048 mg/kg Zn, 2430 mg/kg Cu, 716 mg/kg Mn y 46 mg/kg Cr, respectivamente (Ramos-Arroyo y Siebe-Grabach, 2006;Gómez-Bernal et al.,2017). El desarrollo de abundante vegetación en la mayoría de los depósitos de jales mineros sugiere alta estabilidad química de los EPTs, principalmente porque la vegetación en el sitio de depósito ha establecido algunos mecanismos para extraer, acumular, excluir, inmovilizar, y tolerar altas concentraciones de metales (Shu et al., 2004); sin embargo, el principal problema asociado a los jales mineros es la generación de drenaje ácido de mina (DAM) producido por la oxidación de los minerales tipo sulfuro presentes en este tipo de residuos. Tal oxidación es promovida principalmente por la actividad microbiana (Thiobacillus ferrooxidans), humedad y oxígeno (Nwaila et al; 2021a y b). ...
La caracterización mineralógica durante la evaluación del potencial generador de drenaje ácido para una muestra de jales mineros originaria de Sombrerete Zacatecas demostró que la pirita está ocluida en los silicatos, disminuyendo de esta manera el riesgo de disolución de metales potencialmente tóxicos. Por ello la cuantificación de la concentración de metales base (Cu, Pb y Zn) en conjunto con la extracción secuencial reveló la presencia de aproximadamente 6kg de Cu/tonelada de jale minero. Además, el 80% de cobre se encuentra en forma de carbonatos, óxidos y sulfuros, por lo que se planteó un proceso hidrometalúrgico usando una solución de lixiviación 0.2M de ácido sulfúrico, seguida por el enriquecimiento de cobre a través de la extracción por solventes y su obtención metálica vía electrodeposición, respectivamente. Este proceso demostró que los jales mineros son residuos de minería que pueden considerarse materiales de valor agregado y fuentes secundarias para la recuperación de metales.
... In these environments, the plant diversity and the presence of metal tolerant genes is often low; but stress from pollution, encourages and facilitates the selection of tolerant populations versus non-tolerant within the same species. 123,124,125 Numerous authors analyzed the patterns of accumulation of metals in plants capable of growing in mining areas with high contents of metals, indicating possible use in phytoremediation processes. 90,[126][127][128][129][130][131][132][133] The amount of Hyperaccumulator species is scarce; but there is a significant number of "hypertolerant" species to high levels of metals, this increases the prospects of success for use in the process of phytoremediation of contaminated soils. ...
... Što se tiče jona Cd može se uočiti da odabrane biljne vrste manje usvajaju Cd što je prethodno objašnjeno prisustvom Zn; ipak najbolji rezultat je ostvaren sa C. dactylon. Festuca arundinacea i C. dactylon spadaju u porodicu trava, čije se vrste često odlikuju povećanim stepenom tolerancije na teške metale, kao i dobrom sposobnošću akumulacije istih.[39,40] Najmanju sposobnost usvajanja za jone sva tri metala pokazale su L. sativa i A. cepa.Tabela 2. Koeficijenti i statisticki pokazatelji kvaliteta modela Table 2. Coefficients and statistical indicators of the quality of the model RSE -Residual Standard Error, MRE -Mean Relative Error ...
Izvod Cilj ovog rada je analiza i simulacija procesa bioakumulacije jona Pb 2+ , Cd 2+ i Zn 2+ iz aluvijalnog zemljišta, praćenjem njihove koncentracije pre i nakon zasada biljaka. Simulacijom procesa bioakumulacije razvijen je i usavršen model koji daje zavisnosti koncentracije jona metala u zemljištu pre i nakon zasada biljaka. U radu su analizirani uzorci zemljišta uzeti na severnom delu Kosova i Metohije. U procesu bioakumulacije korišćene su sledeće biljke: a) povrtarske: zelena salata (Lactuca sativa L.) i crni luk (Allium cepa L.); b) leguminoze: zvezdan (Lotus corniculatus L.) i crvena detelina (Trifolium pratense L.) i c) korovske biljke: troskot (Cynodon dactylon (L.) Pers.) i visoki vijuk (Festuca arundinacea Schreb.). Eksperimentalni deo rada izveden je putem vegetacionih ogleda. Koncentracija jona metala određivana je potenciometrijskom striping analizom (PSA). Dobijeni rezultati pokazuju: I) da je koncentracija jona metala u svim uzorcima zemljišta iznad propisanih vrednosti; II) da je različit stepen akumulacije praćenih elemenata u ispitivanim biljnim vrstama. Promena koncentracije jona metala pre i posle zasada modelovana je linearnom regresijom, pri čemu su vrednosti koeficijenata modela određene minimizacijom srednje kvadratne greške. Ključne reči: joni teških metala; zemljište; biljke; PSA; bioakumulacija. NAUČNI RAD UDC 504.5(497.115):631/635:54 Hem. Ind. 00 (0) XXX-XXX (2018) Dostupno na Internetu sa adrese časopisa: http://www.ache.org.rs/HI/ 1. UVOD Zbog načina proizvodnje, toksičnosti, mogućnosti usvajanja od strane biljaka i uključivanja u lanac ishrane, teški metali se sve češće pojavljuju kao dominantni nosioci zagađenosti životne sredine.[1-3] Osim što su nosioci zagađenja, na severnom delu Kosova i Metohije predstavljaju i dobar indikator dejstva proizvodnih procesa i postojećih pasivnih i aktivnih rudnih deponija kombinata Trepča lociranih na ovom prostoru. Usled erozije, dejstva vodotoka i atmosferskih padavina, teški metali iz ovih složenih formacija dospevaju u vazduh, vodu i zemljište. Proizvodne osobine i plodnost zemljišta diktiraju procesi u zemljištu i prisustvo materija koje su veoma važne za biljke.[4] Zagađenje zemljišta teškim metalima, odnosno poznavanje mehanizma usvajanja, raspodele, metabolizma i akumulacije u biljkama od velikog je značaja.[5,6] Biljke različito reaguju na povišene koncentracije metala. Prisustvo teških metala utiče na životne procese biljaka kroz ishranu, vodni režim, fotosintezu, disanje, odnosno kroz sve fizičko−biohemijske procese.[7] Posledice uticaja teških metala na biljke su smanjenje produkcije organske materije i promena hemijskog sastava biljaka [8,9]. Biljke usvajaju teške metale u obliku jona ili organskih kompleksa.[10] Proces usvajanja zavisi od karakteristika samog zemljišta, sadržaja organske materije, pristupačnih nutrijenata, procesa u rizosferi, primene fosfata, kreča, pH vrednosti, intenziteta svetlosti i temperature, kao i gajenog genotipa.[11−14] Česta je pojava narušavanja mehanizama regulacije i usvajanja jona od strane biljaka. Neki autori su utvrdili da među jonima metala postoje antagonizmi i različite reakcije biljaka na prisustvo teških metala.[15,16] Osnovnom analizom zemljišta (u cilju procene međusobne zavisnosti i računanjem korelacionih matrica), utvrđena je i dominantna uloga određenih jona [17]. U ovom radu vršeno je određivanje koncentracija jona Pb 2+ , Cd 2+ i Zn 2+ u aluvijalnom zemljištu i biljkama. Zemljište za analizu je uzimano u selima Rudare, Grabovac, Srbovac i Gornji Krnjin na severnom delu Kosova i Metohije, a od biljaka analizirane su: zelena salata (Lactuca sativa L.) i crni luk (Allium cepa L.) kao biljke koje se intenzivno gaje u navedenom području; zvezdan (Lotus corniculatus L.) i crvena detelina (Trifolium pratense L.), biljke koje se koriste u Korespodencija: Ljiljana M. Babincev, Fakultet tehničkih nauka, Univerzitet u Prištini,
... In a field study, mine wastes containing Cu, Pb and Zn were stabilized by grasses -Agrostis tenuis for acid lead and zinc mine wastes, Agrostis tenuis for copper mine wastes, and Festuca rubra for calcareous lead and zinc mine wastes (Smith and Bradshaw, 1979). Shu et al. (2004) conducted a field experiment to compare the growth and metal accumulation in 4 grasses (Vertiveria zizanioides, Paspalum notatum, Cynodon dactylon and Imparata cylindraca var major) on the fields amended with 10 cm domestic refuse + complex fertilizer (NPK, Treatment A), 10 cm domestic refuse (Treatment B) and complex fertilizer (NPK, Treatment C), respectively, and without any amendment used as control (Treatment D). The results indicated that V. zizanioides was a typical heavy metal excluder, because the concentrations in shoots of the plants were the lowest among the four plant species tested. ...
Phytoremediation is a group of technologies that use plants to reduce, degrade, or immobilize environmental toxins, primarily those of anthropogenic origin, with the aim to clean-up contaminated areas. In this review paper, different types of phytoremediation processes, typical plants used and their application for clean-up of metal contaminated sites were reviewed. Plant responses to heavy metals and mechanisms of metal uptake and transport were also discussed. Phytoremediation of Pb, Zn, Cu and Fe tailings and mine spoils were carried out by grasses, herbs and shrubs, which could be categorised as As accumulator (Paspalum, Eriochloa, Holcus, Pennisetum Juncus, Scirpus and Thymus), Pb accumulator (Brassica juncea, Vetiveria, Sesbania, Minuartia, Juncus, Scirpus and Thymus), Cu accumulator (Ammania baccifera, Scleranthus) Zn and Cd accumulator (Vetiveria, Sesbania, Viola, Sedum, Rumex). The research work showed that, bioavailability and metal uptake by plants could be accomplished by ameliorating pH, addition of organic amendment, fertiliser and chelating agents. Further research is required to develop fast growing high biomass plants with improved metal uptake ability, increased translocation and tolerance of metals through genetic engineering for effective phytoremediation of metal mine wastes.
... In a field study, mine wastes containing Cu, Pb and Zn were stabilized by grasses -Agrostis tenuis for acid lead and zinc mine wastes, Agrostis tenuis for copper mine wastes, and Festuca rubra for calcareous lead and zinc mine wastes (Smith and Bradshaw, 1979). Shu et al. (2004) conducted a field experiment to compare the growth and metal accumulation in 4 grasses (Vertiveria zizanioides, Paspalum notatum, Cynodon dactylon and Imparata cylindraca var major) on the fields amended with 10 cm domestic refuse + complex fertilizer (NPK, Treatment A), 10 cm domestic refuse (Treatment B) and complex fertilizer (NPK, Treatment C), respectively, and without any amendment used as control (Treatment D). The results indicated that V. zizanioides was a typical heavy metal excluder, because the concentrations in shoots of the plants were the lowest among the four plant species tested. ...
... A fi eld experiment by Zhuang et al. ( 2007 ) revealed that Rumex crispus is an ideal candidate for phytoextraction of Zn and Cd from soil. Another fi eld trial conducted by Shu et al. ( 2004 ) compared the growth and metal accumulation ability of four grasses ( Imparata cylindrica var. major , Paspalum notatum , Vetiveria zizanioides and Cynodon dactylon ) supplemented with and without complex fertilizer (NPK) and domestic refuse. ...
Pollution and the global health impacts from toxic environmental pollutants are presently of great concern. At present, more than 100 million people are at risk from exposure to a plethora of toxic organic and inorganic pollutants. This review is an exploration of the ex-situ technologies for cleaning-up the contaminated soil, groundwater and air emissions, highlighting their principles, advantages, deficiencies and the knowledge gaps. Challenges and strategies for removing different types of contaminants, mainly heavy metals and priority organic pollutants, are also described.
... A fi eld experiment by Zhuang et al. ( 2007 ) revealed that Rumex crispus is an ideal candidate for phytoextraction of Zn and Cd from soil. Another fi eld trial conducted by Shu et al. ( 2004 ) compared the growth and metal accumulation ability of four grasses ( Imparata cylindrica var. major , Paspalum notatum , Vetiveria zizanioides and Cynodon dactylon ) supplemented with and without complex fertilizer (NPK) and domestic refuse. ...
Though several in-situ treatment methods exist to remediate polluted sites, selecting an appropriate site-specific remediation technology is challenging and is critical for successful clean up of polluted sites. Hence, a comprehensive overview of all the available remediation technologies to date is necessary to choose the right technology for an anticipated pollutant. This review has critically evaluated the (i) technological profile of existing in-situ remediation approaches for priority and emerging pollutants, (ii) recent innovative technologies for on-site pollutant remediation, and (iii) current challenges as well as future prospects for developing innovative approaches to enhance the efficacy of remediation at contaminated sites.
... Its biomass is extremely high under tropical hot and wet conditions, producing more than 100 tons of dry matter ha −1 year −1 (Truong 2003). In sub-tropical weather, vetiver can produce high dry biomass from 10 to 20 tons after 5-6 months of cultivation ( Yang et al. 2003;Shu et al. 2004). This may be due to the fact that vetiver retains high activity of the key enzymes involved in photosynthesis (NADP-MDH and NADP-MET) even when cultivated in temperate climates (Bertea and Camusso 2002). ...
... mg kg −1 (Chiu, Ye, and Wong, 2006;Wilde, Brigmon, and Dunn, 2005). In field studies, VZ survived cultivation on mine tailing soils containing total Pb of 2078-4164 mg kg −1 , Zn of 2472-4377 mg kg −1 , Cu of 35-174 mg kg −1 , and Cd of 7-32 mg kg −1 (Zhuang et al., 2005;Shu et al., 2004;Yang et al., 2003;Shu et al., 2002). Organic matters (domestic refuse and sewage sludge), inorganic fertilizers and especially the combination of organic matters and inorganic fertilizers greatly enhanced the survival rates, growth and biomass of VZ cultivated on soils contaminated by combinations of heavy metals (Chiu, Ye, and Wong, 2006;Wilde, Brigmon, and Dunn, 2005;Yang et al., 2003;Shu et al., 2002). ...
... Phytoremediation C. dactylon was found to possesses phytoremedial potential against dibenzofuran contaminated soil 48 , fly ash 49 , aged petroleum sludge 50 etc. Bermuda grass can accumulate very high concentration of Pb (0.15-0.65%) 51 and Zn (0.22-1.56%) 51 in the roots 52,53 ; waste elements (like Ca, Cr, Cu, Pb, Zn, Mn and Fe) in wetland plants 54 ; certain concentration of Cu 53,55,56 ; arsenic 56,57 amongst others and thus can serve as potential candidate for revegetation in many heavy metal contaminated wastelands. Wang et al. 58 showed that the species can transform Cu forms in rhizosphere soil. ...
Cynodon dactylon (L.) Pers. (Family- Poaceae), a perennial weedy grass is one of the ten auspicious herbs that constitute the group 'Dasapushpam' in Ayurveda. The species possesses immense therapeutic as well as other potential uses. As the species grow widely as weed, it is a natural resource which can be explored. An overview is conducted on C. dactylon with an objective to provide information on the essential aspects for further exploration in human benefits.
... This area is mainly engaged in mining and smelting, including at the Fankou Pb/Zn Mine, Lechang Pb/Zn Mine, Shaoguan Metallurgical Refinery, and Dabaoshan Mining Group ( Figure 1). Previous studies report high levels of heavy metals, such as cadmium, lead, and zinc, in soils of this area (Shu et al., 2004;Yang et al., 2003). In particular, mean reported concentrations of Pb, Zn, Cu, and Cd are 1490, 1420, 680, and 13.6 mg kg −1 , respectively, in agricultural soils which received Pb/Zn mining wastewater for more than 50 years (Yang et al., 2003). ...
A total of 455 agricultural soil samples from four nonferrous mines/smelting sites in Shaoguan City, China, were investigated for concentrations of 10 heavy metals (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, and Zn). The mean concentrations of the metals were 72.4, 5.16, 13.3, 54.8, 84.5, 1.52, 425, 28.2, 529, and 722 mg kg−1, respectively. The values for As, Cd, Hg, Pb, and Zn were more than 8 and 1.5 times higher than their background values in this region and the limit values of Grade II soil quality standard in China, respectively. Estimated ecological risks based on contamination factors and potential ecological risk factors were also high or very high for As, Cd, Hg, and Pb. Multivariate analysis (Pearson's correlation analysis, hierarchical cluster analysis, and principal component analysis) strongly implied three distinct groups; i.e., As/Cu/Hg/Zn, Co/Cr/Mn/Ni, and Cd/Pb. Local anomalies for As, Cu, Hg, and Zn by a probably anthropogenic source (identified as mining activity), Co, Cr, Mn, and Ni by natural contribution, and a mixed source for Cd and Pb, were identified. This is one of the few studies with a focus on potential sources of heavy metals in agricultural topsoil around mining/smelting sites, providing evidence for establishing priorities in the reduction of ecological risks posed by heavy metals in Southern China and elsewhere.
... mg kg −1 (Chiu, Ye, and Wong, 2006;Wilde, Brigmon, and Dunn, 2005). In field studies, VZ survived cultivation on mine tailing soils containing total Pb of 2078-4164 mg kg −1 , Zn of 2472-4377 mg kg −1 , Cu of 35-174 mg kg −1 , and Cd of 7-32 mg kg −1 (Zhuang et al., 2005;Shu et al., 2004;Yang et al., 2003;Shu et al., 2002). Organic matters (domestic refuse and sewage sludge), inorganic fertilizers and especially the combination of organic matters and inorganic fertilizers greatly enhanced the survival rates, growth and biomass of VZ cultivated on soils contaminated by combinations of heavy metals (Chiu, Ye, and Wong, 2006;Wilde, Brigmon, and Dunn, 2005;Yang et al., 2003;Shu et al., 2002). ...
Glasshouse and field studies showed that Vetiver grass can produce high biomass (>100t/ tha(-1) year(-1)) and highly tolerate extreme climatic variation such as prolonged drought, flood, submergence and temperatures (-15 degrees - 55 degrees C), soils high in acidity and alkalinity (pH 3.3-9.5), high levels of Al (85% saturation percentage), Mn (578 mg kg(-1)), soil salinity (ECse 47.5 dS m(-1)), sodicity (ESP 48%), anda wide range of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn). Vetiver can accumulate heavy metals, particularly lead (shoot 0.4% and root 1%) and zinc (shoot and root 1%). The majority of heavy metals are accumulated in roots thus suitable for phytostabilization, and for phytoextraction with addition of chelating agents. Vetiver can also absorb and promote biodegradation of organic wastes (2,4,6-trinitroluene, phenol, ethidium bromide, benzo[a]pyrene, atrazine). Although Vetiver is not as effective as some other species in heavy metal accumulation, very few plants in the literature have a wide range of tolerance to extremely adverse conditions of climate and growing medium (soil, sand, and railings) combined into one plant as vetiver. All these special characteristics make vetiver a choice plant for phytoremediation of heavy metals and organic wastes.
Discarding fly ash from a coal power plant into a dumpsite does not only contribute to deforestation and loss of productive land but also leads to contamination of air, soil, and groundwater. Therefore, fly ash should be managed properly to avoid the migration of contaminants. One management option is phytoremediation using adapted plants and as a prerequisite, there is a need to identify suitable plants that can be used for revegetation of fly ash dumpsites. To identify prospective plants, a survey was carried out by assessing the plants growing in Morupule B fly ash dumpsite based on their ability to accumulate heavy metals and their bioconcentration (BAF) and translocation factors (TF). Of the twenty-two-plant species growing in the fly ash dumpsite of Morupule B power plant station, N. glauca is a potential phytoextraction agent for Cu (TFCu = 1.02; BAFCu = 2.16) and Pb (TFPb = 1.38; BAFPb = 1.65); P. burchellii for Pb (TFPb = 1.61, BAFPb = 0.9) and Zn (TFZn = 1.35; BAFZn = 5.74); I. pes-tigridis for Pb (TFPb = 1.35; BAFPb = 1.56) and Zn (TFZn = 1.62; BAFZn = 7.43); A. pungens for Cr (TFCr = 1.22; BAFCr = 0.11), Cu (TFCu = 2.18; BAFCu = 1.14), and Zn (TFZn = 1.04; BAFZn = 1.44); E. hirta for Zn (TFZn = 1.54, BAFZn = 2.44); A. spinosus for Pb (TFPb = 1.29; BAFPb = 1.55); C. dactylon for Cu (TFCu = 1.86; BAFCu = 1.07) and Zn (TFZn = 1.00; BAFZn = 2.46); and D. aegyptium for Pb (TFPb = 1.19; BAFPb = 2.57). Other plants growing in the fly ash dumpsite are potential candidates for phytostabilization as they can tolerate a high concentration of metals and low essential nutrients. Also, different plant groups variably modified the pH, EC, OM, and exchangeable fractions of metals in the rhizosphere wherein grasses can increase the OM at higher rates, and it has a higher capacity to acidify and solubilize heavy metals in the rhizosphere leading to higher EC and available metals compared to other plant groups. Overall, the information presented is useful in identifying plants or their combinations for the phytoremediation of fly ash and other heavy metal-polluted environments.
Heavy metal contamination of water and soil is serious problem in recent time and causes hazardous effects on humans and animals which ultimately results in destruction of environment. Heavy metals such as Cd, Cr, Pb, As, Co, Cu, Ni, Zn, Mn, etc. are considered as environmental pollutants due to their toxic effects. Heavy metals alter the plant growth, physiology,and metabolism. It involve in the production of reactive oxygen species which leads to subsequent cell death, eventually results in reduction in crop growth and yield. To sustain the agricultural environment, it is necessary to alleviate the toxicity of heavy metals from the environment. There are number of technologies evolved but, phytoremediation is an emerging technology that uses plants to clean up pollutants from the environment. It is the promising technology for the remediation of contaminated soil because for its low cost, non-intrusiveness, aesthetically pleasing and sustainable features. Hyperaccumulator plants absorb, accumulateand decontaminate very high concentration of metals in their above-ground tissues from natural contaminated site such as mining, smelting, compost, sewage sludge, wastewater, flyash producing areas.
The agricultural and medicinal effect of many natural products from plants and microbes have long been known and used in our day to day life. Even today, more than 75% of the world population relies on plants and plant extracts. There are a number of useful agrochemicals and drugs worldwide that are derived from algae to angiosperms, may provide useful templates to produce more active agrochemicals and pharmaceutical products with less environmental and human risk. In the traditional methods of India, such as Ayurveda, Unani and Homoeopathic systems of medicine entire plant is used for medicinal purpose in various forms. Plants are used for various treatments as antibiotics, antimicrobials, antihelmintic, antipyretic and against Ieucoderma, bronchitis, piles, asthma, tumors, grippe in children, inflammations and various other ailments.
As peace and harmony is the priority in life. This also lies in the hands of our border security. In recent years due to poor border security, the terrorist gained their access into our country and has cost many damages to life and property. If these scenario continues then the peace in the country will become no more. And therefore a well organized and stringent security has to be made sure. Here this paper comprises of a multi level security system using biometrics, Fingerprint scanning along with Iris reorganization. Therefore this implementation promises (a) Faster immigration (b) Criminals or Terrorist can be easily identified Iris and Fingerprint inputs are given by the citizens who emigrate from one country to other country. In control room identifications takes place by fusing inputs then passes the decision signal automatically. The most common unimodal biometric system, it can be seen in most of the places due to its popularity. Its reliability has decreased because it requires larger memory footprint, higher operational cost and it have slower processing speed. So by introducing Multimodal Biometric Identification System 1-3 this uses Iris and Fingerprint for security purpose4. The major advantage of this multimodal approach is that since both modalities utilized the same matcher module the memory footprint of the system is reduced 11. Integrating multiple modalities in user verification and identification leads to high performance, high reliability and high accuracy. So this technique enhances high security in border control and thus saves lives and property.
Tannery industries have been a major source of chromium contamination in and around vellore district, Tamil Nadu, India, which has led to a serious environmental threat to the inhabitants. Our present study focuses on the investigation of accumulation and distribution of chromium in the root and shoot of Mimusops elengi; a commonly found plant in and around the vicinity of tannery industries. The plant samples including whole plant and rhizosphere soil were collected from various distances from the origin point of the industry. All the samples were acid digested and analyzed through Atomic Absorption Spectrophotometery (AAS-Model Varian C). The accumulation and distribution of chromium was detected and it was observed that the concentration of chromium was higher in the roots and shoots of plants growing at a distance of 250m and 500m which was quiet above the permissible limit.
In 2011, research on the impact of road traffic on copper content in leaves, stems and inflorescences of grasses was conducted. Tested plants in the study were three grass species Dactylis glomerata, Arrhenatherum elatius and Al-opecurus pratensis. The plant material used in the study were collected at distances of 1, 5, 10 and 15 m from the edge of the road, on a road section with a length of 9 km. In collected plant parts copper content was estimated by AAS method. The average copper content in above parts of tested grass species was 7.62 mg · kg -1. The highest concentration of Cu (8.28 mg · kg-1) was recorded in the above parts of Arrhenatherum elatius, and the lowest in Alopecurus pratensis (6.93 mg · kg-1). The copper content in the analyzed morphological parts of each tested grass species was significantly different depending on the distance of sampling from the highway. The copper content in the morphological parts of the grass species tested depend on the place of occurrence, and their morphology.
Phytoremediation is considered to be a promising approach to restore or stabilise soil contaminated by lead (Pb). Turfgrasses, due to their high biomass yields, are considered to be suitable for use in phytoextraction of soil contaminated with heavy metal. It has been demonstrated that centipedegrass (Eremochloa ophiuroides (Munro) Hack., Poaceae) is a good turfgrass for restore of soil contaminated by Pb. However, the enhanced tolerant mechanisms in metallicolous (M) centipedegrass accessions remain unknown. In this study, we made a comparative study of growth performance, Pb accumulation, antioxidant levels, and phytochelatin concentrations in roots and shoots from M and nonmetallicolous (NM) centipedegrass accessions. Results showed that turf quality and growth rate were less repressed in M accessions than in NM accession. Pb stress caused generation of reactive oxygen species in centipedegrass with relatively lower levels in M accessions. Antioxidant activity analysis indicated that superoxide dismutase and catalase played important roles in Pb tolerance in M accessions. M accessions accumulated more Pb in roots and shoots. Greatly increased phytochelatins and less repressed sulfur contents in roots and shoots of M accessions indicated that they correlated with Pb accumulation and tolerance in centipedegrass.
Screening plants that are hypertolerant to and excluders of certain heavy metals plays a fundamental role in a remediation strategy for metalliferous mine tailings. A field survey of terrestrial higher plants growing on Mn mine tailings at Huayuan, Hunan Province, China was conducted to identify candidate species for application in phytostabilization of the tailings in this region. In total, 51 species belonging to 21 families were recorded and the 12 dominant plants were investigated for their potential in phytostabilization of heavy metals. Eight plant species, Alternanthera philoxeroides, Artemisia princeps, Bidens frondosa, Bidens pilosa, Cynodon dactylon, Digitaria sanguinalis, Erigeron canadensis, and Setaria plicata accumulated much lower concentrations of heavy metals in shoots and roots than the associated soils and bioconcentration factors (BFs) for Cd, Mn, Pb and Zn were all < 1, demonstrating a high tolerance to heavy metals and poor metals translocation ability. The field investigation also found that these species grew fast, accumulated biomass rapidly and developed a vegetation cover in a relatively short time. Therefore, they are good candidates for phytostabilization purposes and could be used as pioneer species in phytoremediation of Mn mine tailings in this region of South China.
The in situ immobilization of heavy metals using various easily obtainable amendments is a cost-effective and practical method in the remediation of contaminated sites. In this study, two novel industrial waste materials (sweet sorghum vinasse and medicinal herb residues), spent mushroom compost and municipal solid wastes were used as amendments to assess their potential value for the in situ immobilization of heavy metals in tailings from a Pb-Zn mine in South China. Our results demonstrate that all three freely-available organic wastes decrease the deionized water (DW)- and diethylene-triamine-pentaacetic acid (DTPA)-extractable metal concentrations, enhance the enzyme activity, reduce the metal concentration in plant tissues, and could be used for the remediation of these Pb-Zn mine tailings metals by immobilization. The municipal solid waste failed to reduce the metal concentration in tailings and plant tissues and therefore would not be a suitable immobilizing agent. The potential value of these materials as immobilizers of heavy metals and their remediation efficacy deserve further studies in large-scale field trials.
Phytoremediation is widely viewed as an environmentally sound alternative to the destructive physical remediation methods
currently practised. Plants have many endogenous genetic, biochemical, and physiological properties which make them ideal
agents for soil and water remediation. Significant progress has been made in recent years in developing native or genetically
modified plants for the remediation of contaminated environments. Because elements are chemically stable, phytoremediation
strategies for radionuclide and heavy metal pollutants focus on above-ground hyper-accumulation. Soil contaminated with radionuclides
pose a long-term radiation hazard to human health through exposure mainly via the food chain.
The aim of this contribution is to give readers basic knowledge of phytoremediation methodology, including basic definitions, advantages, and potential drawbacks, as well as information about recent developments in this field of research and application.
Lead phytoextraction, using plants to extract Pb from contaminated soils, is an emerging technology. Calculations of soil Pb mass balance suggest that this technology will be economically feasible only if systems can be developed to employ high biomass plants that can accumulate greater than 1% Pb in their shoots. In this study, we investigated the potential of adding chelates to Pb-contaminated soils to increase Pb accumulation in plants. The addition of chelates to a Pb-contaminated soil (total soil Pb 2500 mg kg-1) increased shoot Pb concentrations of corn (Zea mays L. cv. Fiesta) and pea (Pisum sativum L. cv. Sparkle) from less than 500 mg kg-1 to more than 10000 mg kg-1. The surge of Pb accumulation in these plants was associated with the surge of Pb level in the soil solution due to the addition of chelates to the soil. For the chelates tested, the order of the effectiveness in increasing Pb desorption from the soil was EDTA > HEDTA > DTPA > EGTA >EDDHA. We also found that EDTA significantly increased Pb translocation from roots to shoots. Within 24 h after applying EDTA solution [1.0 g of EDTA (kg soil)-1] to the contaminated soil, Pb concentration in the corn xylem sap increased 140-fold, and net Pb translocation from roots to shoots increased 120-fold as compared to the control (no EDTA). These results indicate that chelates enhanced Pb desorption from soil to soil solution, facilitated Pb transport into the xylem, and increased Pb translocation from roots to shoots. Results from this study suggest that with careful management, chelate-assisted Pb phytoextraction may provide a cost-effective soil decontamination strategy.
Toxic metal pollution of waters and soils is a major environmental problem, and most conventional remediation approaches do not provide acceptable solutions. The use of specially selected and engineered metal-accumulating plants for environmental clean-up is an emerging technology called phytoremediation. Three subsets of this technology are applicable to toxic metal remediation: (1) Phytoextraction--the use of metal-accumulating plants to remove toxic metals from soil; (2) Rhizofiltration--the use of plant roots to remove toxic metals from polluted waters; and (3) Phytostabilization--the use of plants to eliminate the bioavailability of toxic metals in soils. Biological mechanisms of toxic metal uptake, translocation and resistance as well as strategies for improving phytoremediation are also discussed.
Phytoremediation is a site remediation strategy, which employs plants to remove non-volatile and immisible soil contents. This sustainable and inexpensive process is emerging as a viable alternative to traditional contaminated land remediation methods. To enhance phytoremediation as a viable strategy, fast growing plants with high metal uptake ability and rapid biomass gain are needed. This paper provides a brief review of studies in the area of phytoaccumulation, most of which have been carried out in Europe and the USA. Particular attention is given to the role of phytochelators in making the heavy metals bio-available to the plant and their symbionts in enhancing the uptake of bio-available heavy metals.
The Lechang Pb/Zn mine is located to the north of the Guangdong Province, South of China. The tailings pond had been abandoned for over 5 years, and revegetation was necessary for stabilizing the bare surface and to reduce its environmental impact. The tailings contained high levels of heavy metals (Pb, Zn, Cu, and Cd) and low levels of major nutrient elements (N, P, and K) and organic matter; therefore, heavy metal toxicity and extreme infertility were the major constraints on revegetation. A field experiment was conducted to compare the growth of Vertiveria zizanioides, Paspalum notatum, Cynodon dactylon, and Imperata cylindrica var. major on the tailings. The tailings were amended with 10 cm domestic refuse + complex fertilizer (NPK) (Treatment A), 10 cm domestic refuse (Treatment B) and complex fertilizer (NPK) (Treatment C), respectively; tailings without any amendment were used as control (Treatment D). Plant growth was improved when either domestic refuse or NPK fertilizer was added to the substrate, but the combination of both amendments gave the best yields. After 6 months' growth, V. zizanioides growing on treatment A had a height of 220 cm, cover of 100% and a yield of 2.1 kg m (d.w.). The height and biomass of V. zizanioides were significantly greater than the other three grasses growing on the same treatment. Judging from results, V. zizanioides was the best species for tailings revegetation, followed by P. notatum, C. dactylon, and I. cylindrica var. major.
The decontamination of soils and wastes polluted with heavy metals presents one of the most intractable problems for soil clean-up. Present technology relies upon metal extraction or immobilization processes, both of which are expensive and which remove all biological activity in the soil during decontamination. They may only be appropriate for small areas of valuable redevelopment land. In this paper the use of metal-accumulating plants is explored for the removal of metals from superficially-contaminated soils such as those resulting from the long-term application to land of metal-contaminated sewage sludges. Green remediation employs plants native to metalliferous soils with a capacity to bioaccumulate metals such as zinc and nickel to concentrations greater than 2% in the aerial plant dry matter (hyperaccumulators). Growing such plants under intensive crop conditions and harvesting the dry matter is proposed as a possible method of metal removal and for ‘polishing’ contaminated agricultural soils down to metal concentrations below statutory limits. Not only are the biological activity and physical structure of soils maintained but the technique is potentially cheap, visually unobtrusive and offers the possibility of biorecovery of metals. The limitations of the process are reviewed and the future requirements for the development of efficient phytoremediators are outlined.
The residues from the extraction of lead/zinc (Pb/Zn) ores of most Pb/Zn mines are permanently stored in tailings ponds, which require revegetation to reduce their environmental impact. This can only be done if the main constraints on plant establishment are evaluated. This can readily be done by field and greenhouse studies. To test this, the properties of different tailings from Lechang Pb/Zn mine located at the north of Guangdong Province in southern China have been studied. Physical and chemical properties including concentrations of metals (Pb, Zn, Cd and Cu) in the tailings and soils collected from different sites have been measured. The results showed that tailings contain low nitrogen (0.016-0.075%), low-organic matter (0.58-1.78%), high salt (3.55-13.85 dS/m), and high total and diethylene-tetramine-pentaacetic acid (DTPA)-extractable metal concentrations (total: 1,019-1,642 microg g(-1) Pb, 3,078-6,773 microg g(-1) Zn, 8-23 microg g(-1) Cd, and 85-192 microg g(-1) Cu; DTPA-extractable: 59-178 microig g(-1) Pb, 21-200 microg g(-1) Zn, 0.30-1.5 mcirog g(-1) Cd, and 4.3-12 microg g(-1) Cu). Aqueous extracts of tailings/soils (10%, 20% and 30%, w/v) from different sites were prepared for testing their effects on seed germination and root elongation of a vegetable crop Brassica chinensis and a grass species Cynodon dactylon. It was found that root elongation provided a better evaluation of toxicity than seed germination. The ranking of toxicity using root elongation was: high-sulfur tailings > tailing dam > sparsely vegetated tailings > densely vegetated tailings > mountain soil for both plants. This order was consistent with DTPA-extractable Pb contents in the tailings and soils. B. chinensis seedlings were then grown in the mixtures of different proportions of tailings and farm soil for 4 weeks, and the results (dry weights of seedlings) were in line with the root elongation test. All these demonstrated that heavy metal toxicity, especially available Pb, low content of nutrient, and poor physical structure were major constraints on plant establishment and colonization on the Pb/Zn mine tailings.
Both Fankou and Lechang lead/zinc (Pb/Zn) mine tailings located at Guangdong Province contained high levels of total and DTPA-extractable Pb, Zn and Cu. Paspalum distichum and Cynodon dactylon were dominant species colonized naturally on the tailings. Lead, zinc and copper accumulation and tolerance of different populations of the two grasses growing on the tailings were investigated. Tillers of these populations including those from an uncontaminated area were subjected to the following concentrations: 5, 10, 20, 30 and 40 mg l(-1) Pb, 2.5, 5, 10, 20 and 30 mg (l-1) Zn, or 0.25, 0.50, 1 and 2 mg l(-1) Cu for 14 days, respectively, then tolerance index (TI) and EC50 (the concentrations of metals in solutions which reduce 50% of normal root growth) were calculated. The results indicated that both Lechang and Fankou populations of the two grasses showed a greater tolerance to the three metals than those growing on the uncontaminated area, which suggested that co-tolerant ecotypes have evolved in the two grasses. P. distichum collected from Fankou tailings had the highest tolerance to Cu while Lechang population the highest tolerance to Pb and Zn among the tested populations, and tolerance levels in P. distichum were related to metal concentrations in the plants. P. distichum had a better growth performance than C. dactylon when both of them were grown on the tailings sites. Tolerant populations of these species would serve as potential candidates for re-vegetation of wastelands contaminated with Pb, Zn and Cu.
Contaminated soils and waters pose a major environmental and human health problem, which may be partially solved by the emerging phytoremediation technology. This cost-effective plant-based approach to remediation takes advantage of the remarkable ability of plants to concentrate elements and compounds from the environment and to metabolize various molecules in their tissues. Toxic heavy metals and organic pollutants are the major targets for phytoremediation. In recent years, knowledge of the physiological and molecular mechanisms of phytoremediation began to emerge together with biological and engineering strategies designed to optimize and improve phytoremediation. In addition, several field trials confirmed the feasibility of using plants for environmental cleanup. This review concentrates on the most developed subsets of phytoremediation technology and on the biological mechanisms that make phytoremediation work.