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Phytoremediation of heavy metals from fly ash pond by Azolla caroliniana
Abstract
Abundance of naturally growing Azolla caroliniana (water fern) on the surface of metal enriched fly ash (FA) pond reflects its toxitolerant characteristics. Results indicate the efficiency of A. caroliniana for phytoremediation of FA pond because of its higher bioconcentration factor. The metal concentration ranged from 175 to 538 and 86 to 753mgkg(-1) in roots and fronds, respectively. Bioconcentration factor (BCF) values of all metals in root and frond ranged from 1.7 to18.6 and 1.8 to 11.0, respectively, which were greater than one and indicates the metal accumulation potential of A. caroliniana. Translocation factor (TF) ranged from 0.37 to 1.4 for various heavy metals. The field result proved that A. caroliniana is a potential accumulator for the examined heavy metals and can be used for phytoremediation of FA pond.
... Removal of Al, As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Ti, and Zn from effluent or wastewater by using Azolla has been confirmed in many studies, providing information for the effective utilization of this species for the treatment of multi-element-contaminated wastewater [19][20][21][22][23][24]. In addition, the potential of several Azolla species for hyperaccumulation of various metals, such as As, Cd, Cr, Cu, Hg, Ni, and Zn, has been demonstrated [17,[23][24][25][26][27]. However, no study to date has focused on the use of Azolla for phytoremediation of metals from WMCF. ...
... In addition, COD is an index of organic pollutants in wastewater, which may damage the cell membrane in A. imbricata [45]. Consistent with the results of the present study, the toxic effects of excess nutrient levels [26,46], elevated COD [47,48], and pH [49] on macrophytes have been reported previously. In addition, the fresh and dry weights of the pooled samples confirmed the above results (Fig. 2a-e). ...
... In Azolla, [8][9][10].5% of the cell wall is composed of pectin, which is responsible for metal binding [60]. To date, many studies have reported on the metal accumulation potential of various Azolla species [17,19,20,23,26,58,[61][62][63][64]. Although the hyperaccumulation potential of Azolla for Cd, Cr, Cu, Ni, and Zn has been noted in laboratory experiments [17,23], these studies tested the effects on a single metal mixed with a nutrient solution. ...
Phytoremediation of metals from water (WM) and nutrient (NM) media exposed to waste metal cutting fluid (WMCF) along with temperature (T) and humidity (H) stress was tested using Azolla imbricata (Roxb.) Nakai. In the absence of WMCF, biomass was higher in NM than in WM during all tests. Surprisingly, opposite results were noted in the presence of WMCF, with growth failing at exposure to > 0.1% and > 0.5% in NM and WM, respectively. Further, correlation analysis of the growth data following WM exposure revealed that biomass was affected positively by T and negatively by H and metal accumulation. Simultaneously, metal accumulation was affected negatively by T and positively by H. The average accumulations of Al, Cd, Cr, Fe, Pb, and Zn across all T/H tests were 540, 282, 71, 1645, 2494 and 1110 mg·kg-1, respectively. The observed bioconcentration factor indicated that A. imbricata acts as a hyperaccumulator or accumulator of Zn (>10) and as either accumulator (>1) or excluder (<1) of the other metals. Overall, the phytoremediation performance of A. imbricata in multi-metal-contaminated WMCF was high in WM under all environmental conditions. Therefore, the use of WM is an economically feasible approach for the removal of metals from WMCF.
... Nevertheless, a differential response of plants was observed in BCF values after their exposure to Cu. The BCF is an indicative parameter to estimate the suitability of plants for the phytoremediation of metals [23]. Higher BCF values (>1000) are indicating better suitability of plants to remediate contaminants from the environment [34,35]. ...
... Biomass is an allosteric parameter and an important trait in growth and biomass analysis. Substantial growth response after exposure to Cu solutions indicated that these free- The BCF is an indicative parameter to estimate the suitability of plants for the phytoremediation of metals [23]. Higher BCF values (>1000) are indicating better suitability of plants to remediate contaminants from the environment [34,35]. ...
... Higher BCF values (>1000) are indicating better suitability of plants to remediate contaminants from the environment [34,35]. The results of the present study are in agreement with Pandey (2012) Translocation factor (TF) values of three different Azolla species exposed to different Cu solutions are shown in Figure 4B. The translocation factor is an indicator of metal translocation from rooting media to plant parts. ...
The phytoremediation potential of aquatic plants, particularly for Cu, is scarcely reported in the pertinent literature. In this regard, differential growth behavior and phytoaccumulation ability of three free-floating Azolla species (A. japonica, A. pinnata, and A. hybrid) were evaluated in a climatically controlled (a temperature of 25/20 °C, light/dark 16/8 h, a light intensity of 60 µmol m−2 s−1, and a relative humidity of 65%) microcosm study. Azolla plants were exposed to solutions having three Cu concentrations (0, 3, and 6 mg L−1) under two incubation periods (4 and 8 days). Different Cu treatments significantly reduced Azolla biomass during both incubation periods and A. pinnata was the most sensitive species. Azolla plants grown in aqueous solutions showed substantial variations in Cu removal capacity. Higher bioconcentration values displayed by Azolla plants indicated that these plants can be deployed as potential plants for Cu removal from Cu contaminated water. Nevertheless, the plants exposed to higher Cu concentrations displayed color changes and root detachment due to Cu phytotoxic effects which may also ultimately lead to plant death. Significant correlations between Cu removed from the aqueous solutions and Cu contents of plant biomass indicated that Cu phytoremediation by Azolla plants was due to the phytoaccumulation mechanism because the removed Cu from aqueous solutions was accumulated in plant biomass. Introduced Azolla species, i.e., A. hybrid, displayed comparable Cu removal efficiency with naturally grown Azolla species, i.e., A. japonica and A. pinnata. Tested Azolla species proved to be suitable candidates to remediate Cu contaminated water and can be deployed for phytoremediation.
... Nevertheless, a differential response of plants was observed in BCF values after their exposure to Cu. The BCF is an indicative parameter to estimate the suitability of plants for the phytoremediation of metals [23]. Higher BCF values (>1000) are indicating better suitability of plants to remediate contaminants from the environment [34,35]. ...
... Biomass is an allosteric parameter and an important trait in growth and biomass analysis. Substantial growth response after exposure to Cu solutions indicated that these free- The BCF is an indicative parameter to estimate the suitability of plants for the phytoremediation of metals [23]. Higher BCF values (>1000) are indicating better suitability of plants to remediate contaminants from the environment [34,35]. ...
... Higher BCF values (>1000) are indicating better suitability of plants to remediate contaminants from the environment [34,35]. The results of the present study are in agreement with Pandey (2012) Translocation factor (TF) values of three different Azolla species exposed to different Cu solutions are shown in Figure 4B. The translocation factor is an indicator of metal translocation from rooting media to plant parts. ...
The phytoremediation potential of aquatic plants, particularly for Cu, is scarcely reported in the pertinent literature. In this regard, differential growth behavior and phytoaccumulation ability of three free-floating Azolla species (A. japonica, A. pinnata, and A. hybrid) were evaluated in a climatically controlled (a temperature of 25/20 °C, light/dark 16/8 h, a light intensity of 60 µmol m−2 s−1, and a relative humidity of 65%) microcosm study. Azolla plants were exposed to solutions having three Cu concentrations (0, 3, and 6 mg L−1) under two incubation periods (4 and 8 days). Different Cu treatments significantly reduced Azolla biomass during both incubation periods and A. pinnata was the most sensitive species. Azolla plants grown in aqueous solutions showed substantial variations in Cu removal capacity. Higher bioconcentration values displayed by Azolla plants indicated that these plants can be deployed as potential plants for Cu removal from Cu contaminated water. Nevertheless, the plants exposed to higher Cu concentrations displayed color changes and root detachment due to Cu phytotoxic effects which may also ultimately lead to plant death. Significant correlations between Cu removed from the aqueous solutions and Cu contents of plant biomass indicated that Cu phytoremediation by Azolla plants was due to the phytoaccumulation mechanism because the removed Cu from aqueous solutions was accumulated in plant biomass. Introduced Azolla species, i.e., A. hybrid, displayed comparable Cu removal efficiency with naturally grown Azolla species, i.e., A. japonica and A. pinnata. Tested Azolla species proved to be suitable candidates to remediate Cu contaminated water and can be deployed for phytoremediation.
... > B (54.5) >Cr (37.2) >Zn (31.33) > Cu (18.7) > Ni (16.93) > Co (7.7) >Pb (4.23) due to the heterogeneous nature of parent coal (Dwivedi et al. 2008). In India, FA is usually basic due to the low sulfur concentration of the parent coal and the occurrence of calcium and magnesium hydroxides and carbonates (Pandey 2012b). The metal absorption in plant parts varies in different plant species some are metal accumulators, and some are metal tolerant. ...
... In B. monnieri, Pb accumulated in the shoot, while in A. Oleracea, Zn accumulated more may be the reason Cd was not present in FA according to our study. Our study is also supported by Pandey (2012b) in Azolla. The B. monnieri also supports the removal of the toxic metal Cr, it is a hyperaccumulator plant, but it is a medicinal plant too (Rai et al. 1995). ...
... Many types of invasive species live in water bodies, such as water hyacinth (Eichhornia crassipes), creeping water primrose (Ludwigia adscendens), flowering pickerel weeds (Monochoria vaginalis), African water weeds (Monochoria africana), water lettuce (Pistia stratiotes L.), lesser bulrush (Typha angustifolia), Kariba weeds (Salvinia molesta), mosquito fern (Azolla pinnata), and yellow velvetleaf (Limnocharis fava). These aquatic species occupy the same niche in the water area, causing direct interactions with the ecosystem (Pandey, 2012). One of the most well-known invasive aquatic plants is the water hyacinth. ...
... Water plants, especially water hyacinth, have been widely studied for phytoremediation (Pandey, 2012;Rezania et al., 2015;Ting et al., 2018) for removing organic, inorganic, and heavy metal pollutants in water. Current reports on the utilization of water hyacinths for phytoremediation for removing chemicals (such as nitrogen, phosphorous, ammonia, Fe, Cu, Cr, Zn, Pb, Cd, and Ni), as well as connection to the COD, total nitrogen (TN), total phosphorus (TP), total suspended solids (TSS), BOD, and DO, are presented in Table 2. ...
Water hyacinth (Eichhornia crassipes) is considered a prospective free-floating aquatic plant potentially used to address current issues on food, energy, and the environment. It can grow quickly and easily in various tropical and subtropical environments as long as it has access to adequate light and water to support photosynthetic growth. Ecosystems are threatened by their invasive growth and remarkable capacity for adaptation. However, managing this plant can result in valuable products. This paper demonstrates particle technologies that might be used to utilize water hyacinths, including brake pads, fertilizer, bioenergy, animal feed, phytoremediation agents, bioplastics, and adsorbents. This study is accompanied by a discussion based on the conducted experiments and currently available literature, providing readers with a clearer understanding. Water hyacinth's capacity to absorb macro- and micro-nutrients, nitrogen, and phosphorus makes it a good plant for phytoremediation. The prospect of producing cellulose makes it prospective as a biomass energy source and livestock feeding. Further, it can be transformed into high-cellulose content particles for applications in bioplastics, brake pads, and adsorbents. The current reports regarding education of water hyacinth to student also were added. Finally, issues and suggestions for future development related to the use of water hyacinths are discussed. This study is expected to provide comprehensive knowledge on how to turn invasive water hyacinth plants into valuable products.
... (Kumari and Pathania, 2016) [20] collected 28 species from different parts of Himachal Pradesh, from vidarbh region (Tiple, 2011) [29] ; recorded 167 species and found most of the species were active in monsoon season and some remain active throughout the year. (Pandey et al., 2012) [34] ; (Singh and Sodhi, 2016) [28] ; (Jagat and Tiple, 2020) [17] , and so many workers, studied the diversity and distribution of butterflies in different regions. According to different studies the population of butterflies and other insects is declining day by day this declining will lead to adverse effects on different ecosystems, butterflies are one of the best bio indicators of any ecological and environmental surveys and their presence shows us the impact of climate change, change in land use and degradation of habitat. ...
... (Kumari and Pathania, 2016) [20] collected 28 species from different parts of Himachal Pradesh, from vidarbh region (Tiple, 2011) [29] ; recorded 167 species and found most of the species were active in monsoon season and some remain active throughout the year. (Pandey et al., 2012) [34] ; (Singh and Sodhi, 2016) [28] ; (Jagat and Tiple, 2020) [17] , and so many workers, studied the diversity and distribution of butterflies in different regions. According to different studies the population of butterflies and other insects is declining day by day this declining will lead to adverse effects on different ecosystems, butterflies are one of the best bio indicators of any ecological and environmental surveys and their presence shows us the impact of climate change, change in land use and degradation of habitat. ...
... Bio concentration factor (BCF) and Translocation factor (TF) evaluates the feasibility of plant for the phytoremediation of heavy metals (Pandey, 2012) [12] . The digested samples were analyzed for Cu and Pb and the BCF and TF of each metal were calculated separately using the following formula, BCF = Trace element concentration in plant tissue at harvest / Initial concentration of the element in water According to Zhu et al., (1999) [23] a BCF value ≥ 1000 has been suggested to indicate that a plant species are hyperaccumulator. ...
... Bio concentration factor (BCF) and Translocation factor (TF) evaluates the feasibility of plant for the phytoremediation of heavy metals (Pandey, 2012) [12] . The digested samples were analyzed for Cu and Pb and the BCF and TF of each metal were calculated separately using the following formula, BCF = Trace element concentration in plant tissue at harvest / Initial concentration of the element in water According to Zhu et al., (1999) [23] a BCF value ≥ 1000 has been suggested to indicate that a plant species are hyperaccumulator. ...
Wastewater management is of prime importance in the era of water deficiency for domestic purposes, agriculture and aquaculture. Phytoremediation involves utilisation of aquatic plants for remediating heavy metals and other pollutants from aquatic ecosystems. Efficiency of Eichhornia crassipes (Mart.) Solms as a potential bioremidiator in the Ramsar site Nalban bheri wetland of West Bengal is studied here. About 120 ha of area of Nalban bheri wetland were selected for the study, and were divided into three sections. Floating weed Eichhornia crassipes were maintained on water spread area and were screened for the presence and accumulation of heavy metals in plants, monthly. Bioconcentration factor and translocation factor were also estimated and discussed herewith. The present study recommends water hyacinth as a potential bioremidiator for controlling heavy metals in open freshwater bodies
... The potential for Azolla spp. in phytoremediation has already proved effective in the uptake of heavy metals, dyes and some surfactants (Hassanzadeh et al., 2021;Masoudian et al., 2020;Padmesh et al., 2006;Pandey, 2012;Sood et al., 2012;Vafaei et al., 2012). However, their potential for phytoremediation of POPs, including PFAS, is yet to be explored. ...
Environmental contamination of aquatic systems by per‐ and polyfluoroalkyl substances (PFAS) has generated significant health concerns. Remediation of contaminated sites such as the fire‐fighting emergency training grounds that use aqueous film‐forming foams is a high priority. Phytoremediation may help play a part in removing PFAS from such contaminated waters. We investigated the potential of the water fern Azolla filiculoides, which is used for phytoremediation of a wide range of contaminants, to uptake seven common PFAS (perfluorobutanoic acid [PFBA], perfluorobutane sulfonic acid [PFBS], perfluoroheptanoic acid [PFHpA], perfluorohexanoic acid [PFHxA], perfluorohexane sulfonic acid [PFHxS], perfluorooctanoic acid [PFOA], and perfluoropentanoic acid [PFPeA]), during a 12‐day exposure to environmentally relevant concentrations delivered as equimolar mixtures: low (∑PFAS = 0.0123 ± 1.89 μmol L ⁻¹ ), medium (∑PFAS = 0.123 ± 2.88 μmol L ⁻¹ ), and high (∑PFAS = 1.39 μmol L ⁻¹ ) treatments, equivalent to approximately 5, 50, and 500 µg L ⁻¹ total PFAS, respectively. The possible phytotoxic effects of PFAS were measured at 3‐day intervals using chlorophyll a content, photosystem II efficiency ( F v / F m ), performance index, and specific growth rate. The PFAS concentrations in plant tissue and water were also measured every 3 days using ultra‐high‐performance liquid chromatography—tandem mass spectrometry. Treatments with PFAS did not lead to any detectable phytotoxic effects. All seven PFAS were detected in plant tissue, with the greatest uptake occurring during the first 6 days of exposure. After 12 days of exposure, a maximum bioconcentration factor was recorded for PFBA of 1.30 and a minimum of 0.192 for PFBS. Consequently, the application of Azolla spp. as a stand‐alone system for phytoremediation of PFAS in aquatic environments is not sufficient to substantially reduce PFAS concentrations. Environ Toxicol Chem 2024;00:1–12. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
... Because of this, there has been a discernible rise in the usage of FA in agricultural ecosystems. Although FA contains heavy metals like As, Hg, Pb, Se, Cd, and Cr (Pandey and Sing 2010;Pandey 2012Pandey , 2020, using FA in agricultural regions at low concentrations within the permissible level can be beneficial for improving crop productivity without causing toxicity, as previously described by several researchers Pandey et al. 2016;Bhattacharya et al. 2021). The physicochemical characteristics of soil, such as bulk density, porosity, pH, water-holding capacity, and electrical conductivity, are improved by FA (Raj and Mohan 2014;Ahmad et al. 2021). ...
The sustainable management of large amounts of fly ash (FA) is a concern for researchers, and we aim to determine the FA application in plant development and nematicidal activity in the current study. A pot study is therefore performed to assess the effects of adding different, FA-concentrations to soil (w/w) on the infection of chickpea plants with the root-knot nematode Meloidogyne incognita. Sequence characteristic amplified region (SCAR) and internal transcribed spacer (ITS) region-based-markers were used to molecularly confirm M. incognita. With better plant growth and chickpea yield performance, FA enhanced the nutritious components of the soil. When compared with untreated, uninoculated control (UUC) plants, the inoculation of M. incognita dramatically reduced chickpea plant growth, yield biomass, and metabolism. The findings showed that the potential of FA to lessen the root-knot nematode illness in respect of galls, egg-masses, and reproductive attributes may be used to explain the mitigating effect of FA. Fascinatingly, compared with the untreated, inoculated control (UIC) plants, the FA treatment, primarily at 20%, considerably (p ≤ 0.05) boosted plant growth, yield biomass, and pigment content. Additionally, when the amounts of FA rose, the activity of antioxidants like superoxide dismutase-SOD, catalase-CAT, and peroxidase-POX as well as osmo-protectants like proline gradually increased. Therefore, our findings imply that 20% FA can be successfully applied as a potential strategy to increase biomass yield and plant growth while simultaneously reducing M. incognita infection in chickpea plants.
... Las especies que tienen esta estrategia poseen la capacidad de adaptarse y desarrollarse en ambientes altamente contaminados (Fischerová et al. 2006, Bonanno y Cirelli 2017. Lo contrario ocurre con las especies de plantas donde es bajo el factor de translocación de sustancias tóxicas desde la raíz a los órganos aéreos (inferior a la unidad), lo que quiere decir que estas plantas son menos adecuadas para realizar fitoextración y/o fitorremediación (Yoon et al. 2006, Pandey 2012, Bonanno et al. 2018a. ...
La minería es una actividad que genera bienes a la sociedad, pero a su vez deja nefastas consecuencias en el medio ambiente como la deforestación de los bosques y la contaminación de los suelos, agua y aire. Esta actividad está generando preocupa- ción, por el uso indiscriminado de productos químicos como el mercurio (Hg), que produce problemas ambientales casi irreversibles, porque el Hg se bioacumula y biomagnifica hasta llegar al hombre, causando problemas de salud. El objetivo de este estudio es determinar el papel que juega la minería en la distribución y contaminación de mercurio en el Chocó, Colombia, y el papel que realizan las macrófitas como posibles estrategias biológicas de descontaminación. Se hizo una búsqueda exhaustiva en los distintos buscadores digitales, como Scopus y ScienceDirect. Se concluye que la actividad minera del oro se relaciona directamente con la contaminación de mercurio en el ambiente y que la mejor estrategia para disminuir las concentraciones por metales pesados en ambientes acuáticos es la fitorremediación utilizando macrófitas.
... To date, the role of higher aquatic plants as a powerful factor in the process of selfpurification of polluted water bodies has been clarified [2,3,4,5,6,7,8,9,10]. ...
This article is about accelerating wastewater treatment through a biological method - creating thickets of aquatic and water-coastal plants. Many species of higher aquatic plants grow quite well in various polluted waters and produce large amounts of biomass. At the same time, they absorb mineral and organic components from polluted waters, necessary for the microbiological oxidation of organic substances. In order to determine the purification effect of Lemna minor L., Wolffia arrhiza and Azolla caroliniana, the authors describe experiments conducted on municipal water in Osh and wastewater from a poultry farm. Planting material of plants grown in the laboratory was added to pools with wastewater at the rate of 400 g of duckweed, 500 g of Wolffia and 400 g of Azolla of fresh biomass per 1 m2 . The temperature was monitored and the pH was measured daily. The chemical composition and physical properties of the test waters were determined every 3 days. When growing the above plants, municipal and wastewater from poultry farms is enriched with oxygen, and the degree of purification from organic and mineral substances is intensified. As a result, the authors come to the conclusion that Lemna minor, Wolffia arrhiza and Azolla caroliniana can be used for wastewater treatment, since they are capable of detoxifying it. They extract nitrogen, phosphorus and potassium from water and store nitrogen, phosphorus and potassium in their shoots, and also absorb carbon dioxide and enrich the water with oxygen.
... Many studies have shown that Azolla accumulates organic and inorganic pollutants and shows tolerance to pollutants at certain concentrations (Kösesakal and Seyhan, 2023a;Kösesakal and Seyhan, 2023b;Kösesakal et al., 2016;Masoudian, Salehi-Lisar and Norastehnia, 2020;Zazouli et al., 2014;Pandey, 2012). Previous studies have revealed that Azolla has phytoremediation potential (Sood et al., 2012). ...
The escalating trends of industrialization and urbanization have precipitated the swift contamination of vital freshwater reservoirs by environmental pollution. Inorganic chemicals, notably heavy metals (HMs), give rise to a spectrum of environmental and economic issues. Furthermore, these contaminants exert deleterious effects on soil and water quality, as well as on the nutritional dynamics of plants and animals, consequently impacting human health. HMs such as zinc (Zn), nickel (Ni), copper (Cu), cadmium (Cd), lead (Pb), arsenic (As), and chromium (Cr) rank among the most pervasive water pollutants, posing a significant menace to the environment. The indispensability of water for human sustenance, coupled with an increasing global awareness of environmental matters, especially within aquatic ecosystems, has spurred researchers worldwide to focus on the development of cost-effective and environmentally friendly technologies for the removal of both organic and inorganic pollutants, thereby enhancing water quality.
In this context, phytoremediation emerges as a promising and sustainable technology for the removal of inorganic pollutants from freshwater sources. However, the efficacy of phytoremediation varies among plant species due to differences in growth patterns, biomass production, developmental stages, and pollution levels. Among aquatic plants, a free-floating fern, Azolla, characterized by its rapid growth, and nitrogen-fixing properties, stands out as a compelling candidate for the extraction, disposal, and recovery of pollutants from aquatic ecosystems. Azolla species demonstrate a notable capacity for phytoremediation and bioconcentration in media contaminated with HMs. Nevertheless, it is crucial to acknowledge that HM concentrations exert morphological, physiological, and molecular effects on plants.
This review critically assesses the physiological, biochemical, and molecular impacts of HMs contamination on Azolla species, shedding light on the potential application of this plant for phytoremediation purposes.
... Due to the antagonistic effects of both metals, it is possible to link this decrease in Cd uptake, at least in part, to the rise in Zn levels 143 . Zn and Cd compete with each other because both are transported to the root surface plasma membrane by a common carrier 144 . Since the adsorption of Zn is easier than that of Cd, Cd phytoaccumulation is reduced when Zn is present 145 . ...
Pollution by heavy metals (HMs) has become a global problem for agriculture and the environment. In this study, the effects of pristine biochar and biochar modified with manganese dioxide (BC@MnO2) and zinc oxide (BC@ZnO) nanoparticles on the immobilization and bioavailability of Pb, Cd, Zn, and Ni in soil under ryegrass (Lolium perenne L.) cultivation were investigated. The results of SEM–EDX, FTIR, and XRD showed that ZnO and MnO2 nanoparticles were successfully loaded onto biochar. The results showed that BC, BC@MnO2 and BC@ZnO treatments significantly increased shoots and roots dry weight of ryegrass compared to the control. The maximum dry weight of root and shoot (1.365 g pot⁻¹ and 4.163 g pot⁻¹, respectively) was reached at 1% BC@MnO2. The HMs uptake by ryegrass roots and shoots decreased significantly after addition of amendments. The lowest Pb, Cd, Zn and Ni uptake in the plant shoot (13.176, 24.92, 32.407, and 53.88 µg pot⁻¹, respectively) was obtained in the 1% BC@MnO2 treatment. Modified biochar was more successful in reducing HMs uptake by ryegrass and improving plant growth than pristine biochar and can therefore be used as an efficient and cost effective amendment for the remediation of HMs contaminated soils. The lowest HMs translocation (TF) and bioconcentration factors were related to the 1% BC@MnO2 treatment. Therefore, BC@MnO2 was the most successful treatment for HMs immobilization in soil. Also, a comparison of the TF values of plant showed that ryegrass had a good ability to accumulate all studied HMs in its roots, and it is a suitable plant for HMs phytostabilization.
... The heavy metal contamination has surged in recent years due to rapid industrialization, use of sewage waste water for irrigation, increased use of chemicals for agriculture (de Oliveira 2019). Commonly reported heavy metals are Aluminium (Al), Cadmium (Cd), Chromium (Cr), Copper (Cu), Lead (Pb), Manganese (Mn), Zinc (Zn) and some metalloids such as Antimony (Sb) and Arsenic (As) (Pandey 2012;Hussain et al., 2018). In plants, heavy metal stress induces oxidative stress that affect root growth and expansion, ultimately leading to slowed or stunted plant growth (Gerhardt et al., 2009;Hu et al., 2016). ...
... Numerous research dedicated to analyzing heavy metal accumulation by herbaceous species 13,15 . There are several studies about the accumulation of heavy metals in fly ash lagoons and fields around coal-fired power stations which are contaminated with fly ash 17,18,19,20 . ...
Storage of ash and slag waste causes a number of environmental problems, including the transformation of natural geochemical cycles and the change of the natural radioactive background due to the increased concentration of heavy metals and radioactive isotopes in coal combustion products. Plants can provide an effective approach for the analysis and monitoring of heavy metals contamination. Additionally, vegetation plays a significant role in the restoration and remediation of heavy metal-contaminated soils. The application of plants in phytoremediation is a green and sustainable solution for decontaminating polluted sites. Moreover, the key role in the restoration of contaminated sites belongs to native species. Within the presented research, the abilities of native dominant species to accumulate and tolerate heavy metals in conditions of ash and slag dumps were investigated on a limited number of samples. Primary analysis of the bioaccumulation of heavy metals through the bioaccumulation coefficient showed that zinc has the highest accumulation capacity in the studied species. The ability to bioaccumulate the analyzed heavy metals decreases in the following order: Zn > Fe > Cu > Mn > Cd > Ni > Pb. Indexing the biogeochemical activity of the tested species showed higher levels of biochemical activity for Anthemis arvensis L. than for Achillea millefolium L., however, these data need to be confirmed by statistical analysis. Determination of the translocation index of elements reflected the high mobility of zinc and cadmium with a high rate of transferring to above-ground biomass, but the potential for accumulation requires scaling up the experiment with the involvement of a larger number of samples and performing statistical data processing. Due to their ability to accumulate heavy metals in roots, plant species could be used for phytostabilization. Establishing methods of biomonitoring and the development of green reclamation technologies with native species application need further research with both selected species and other local species. The presented research showed primary results of bioindication and references for phytoremediation of heavy metal contamination of the ash and slag dumps, which is relevant for other similar environmental conditions.
... Various physicochemical and biological techniques have been developed and applied to extract heavy metal contamination from the environment but have failed due to their expense and environmentally unsafe nature (Doble and Kumar, 2005). Therefore, the use of microbe or soil rhizospheric bacteria represents a promising alternative to removing heavy metals including Cu, Zn, Pb, Cd, Zn, and Cr (Aafi et al., 2012;Yang et al., 2012;Pandey, 2012). The use of Pseudomonas fluorescens G10 and Microbacterium sp. ...
Establishing global sustainable agriculture emerges as the primary, indispensable strategy to meet escalating food demands and address environmental preservation amidst the challenges posed by severe climate change. The intricate communities of microorganisms associated with plants, collectively termed the plant microbiome, wield significant influence over the vitality and productivity of plant species. Unleashing the potential of the plant microbiome stands as a pivotal approach to safeguard and rejuvenate our planet. However, the complex nature of microbiome interactions, coupled with their limited persistence in intricate environmental settings due to gaps in understanding or technological limitations, has impeded substantial progress in this field. This review explores innovative and revitalized strategies for harnessing microbiome-based enhancements in crop fitness. Additionally, we illuminate the challenges encountered in deciphering the intricate interplay between the microbiome and its host, particularly in the context of mitigating the adverse influences of climate change on crop resilience. To navigate these complexities, we advocate for a comprehensive approach that considers both host and microbiome-oriented perspectives. This dual-focused strategy aims to overcome current limitations and pave the way toward a future where microbiome intervention forms the bedrock of sustainable agriculture and environmental protection.
... In the flying ash ponds of NTPC Unchahar, which is located in Uttar Pradesh, India, the potential of Azolla caroliniana Willd. as a heavy metal accumulator was investigated [17]. The effectiveness of Pontederia crassipes Mart. in the phytoremediation of Amravati River bank polluted dye industrial water was also studied [18]. ...
Phytoremediation is using live plants to remove toxins and contaminants from land, water, or the air. Hydrocarbons, radionucleotides, fertilizers, explosives, heavy metals, and other contaminants are all efficiently removed from wastewater by this approach. Aquatic plants can be classified as free-floating, emergent, or submerged. Studies have been done on the capacity of Pontederia crassipes Mart. to extract pollutants like dissolved solids, and heavy metals from wastewater. The pollution of chromium in Indian chromite mining sites has also been addressed it and following phytoremediation, the biomass may be utilized to produce vermicompost, biogas, and bioethanol. Surface mining is producing changes in land use, land cover, and climate in the RCF area of West Bengal, India. By using aquatic plants to phytoremediate pit lakes (PLs), fresh water can be produced and chances for sustainable livelihoods can be created. The population in former mining regions has grown significantly, leading to the relinquishment of agriculture and the development of illegal mining and coal theft. This study aims to examine the literature on aquatic plant phytoremediation of water, emphasizing the necessity of phytoremediation of PL water in RCF and the potential applications of Pontederia crassipes Mart. biomass for the generation of biogas, bioethanol, and vermicompost.
... (Gafoori et al. 2011), Azolla caroliniana Willd. (Pandey 2012), Amaranthus dubius Mart. (Mellem et al. 2012) showed a significant translocation of Cr from roots to aerial parts and thus, suggested that these species have a high phytoremediation potential. ...
Intensive industrial activities have elevated chromium (Cr) concentrations in the environment, particularly in soil and water, posing a significant threat due to its cytotoxic and carcinogenic properties. Phytoremediation has emerged as a sustainable and economical alternative for detoxifying pollutants. In this context, an attempt has been made to assess the efficacy of Cr remediation by the invasive plant Alternanthera tenella Colla. The study investigated morphological, anatomical, and physiological adaptations in plant tissues in response to 240 µM of K2Cr2O7, considering elemental distribution patterns and bioaccumulation potential. Growth parameter assessments revealed a notable 50% reduction in root elongation and biomass content; however, the plant exhibited a comparatively higher tolerance index (47%) under Cr stress. Chromium significantly influenced macro and micro-elemental distribution in plant tissues, particularly in roots and leaves. Structural modifications, including changes in the thickness and diameter of xylem walls in the root, stem, and leaf tissues of Cr-treated A. tenella, were observed. Distinct cell structural distortions and Cr deposit inclusions in the xylem wall and inner parenchyma cells were distinct. Under Cr stress, there was a reduction in pigment content and metabolites such as proteins and soluble sugars, while proline, phenol, and malondialdehyde showed a twofold increase. The concentration of Cr was higher in the shoots of A. tenella (185.7 mg/kg DW) than in the roots (179.625 mg/kg DW). With a high BCFroot value (16.23) and TF > 1, coupled with effective mechanisms to cope with metal stress, A. tenella emerges as an ideal candidate for chromium phytoextraction.
... It can easily grow in all types of soil especially alkaline and dry. 15 Even though it cultivates barren and plentiful in the cis-Himalayan zone and is also cultured for therapeutic and ornate objectives in India. 16 Like of neem bush, numerous fragments of China berry shrubs like greeneries, floras, and berries, and their bark have healing value as they are used for curative diverse skin ailments including ulcer injuries, herpes, Hansen's disease, dermatitis, scrofula disease, etc. 16 Even if Neem, is also an associate of the identical family, has been considered as a "feedstock" for making bio-diesel. ...
... Biyogübreler, nitrojen fiksasyonu, fosfat çözündürme, bitki büyümesini teşvik edici maddelerin salgılanması ve toprakta biyolojik bozunma gibi biyolojik işlemler yoluyla besin açısından önemli elementleri kullanılamaz formdan kullanılabilir forma dönüştürme yeteneğine sahip bir veya daha fazla mikroorganizma türü içeren ürünlerdir. Başka bir deyişle biyogübreler, tek başına veya kombinasyon halinde bakteri, alg, mantar gibi canlı mikrobiyal aşılayıcılar vasıtasıyla bitkilere besin tedariki sağlayan doğal gübrelerdir (Pandey, 2012). ...
... Biyogübreler, nitrojen fiksasyonu, fosfat çözündürme, bitki büyümesini teşvik edici maddelerin salgılanması ve toprakta biyolojik bozunma gibi biyolojik işlemler yoluyla besin açısından önemli elementleri kullanılamaz formdan kullanılabilir forma dönüştürme yeteneğine sahip bir veya daha fazla mikroorganizma türü içeren ürünlerdir. Başka bir deyişle biyogübreler, tek başına veya kombinasyon halinde bakteri, alg, mantar gibi canlı mikrobiyal aşılayıcılar vasıtasıyla bitkilere besin tedariki sağlayan doğal gübrelerdir (Pandey, 2012). ...
... Similarly, Kumar et al. (2020) found that the removal percentage of Cd, Cu, Fe, Cr, and Zn by A. pinnata from 60% of integrated industrial effluent (IIE) was 57.27, 53.85, 56.06, 58.06, and 60.03%, respectively. Pandey (2012) found that the accumulation rates of heavy metals by A. caroliniana from a fly ash pond were as follow: ...
One of the most significant environmental challenges in the twenty-first century is heavy metal pollution. The potential use of fresh Azolla pinnata to alleviate the toxic effects of Cd and Co on the germination measurements of wheat seeds (Triticum aestivum L.) and the biochemistry of seedlings was studied. Two concentrations (80 and 100 mg L⁻¹ solutions) of CdNO3 and CoCl2 were used before and after treatment with A. pinnata. The highest removal efficiency (RE) by A. pinnata was obtained on the fifth day, with a Cd RE = 55.9 and 49.9% at 80 and 100 mg L⁻¹, respectively. Cadmium and cobalt solutions reduced the germination percentage, and the measured variables of wheat seeds meanwhile increased the radicle phytotoxicity. In contrast, the presence of A. pinnata in the germination medium increased all the measured variables and decreased radicle phytotoxicity. At 80 and 100 mg L⁻¹, Cd significantly reduced the fresh and dry biomass, and height of wheat seedlings after 21 days of cultivation compared to Co. Cadmium and high concentrations of cobalt increased the contents of H2O2, proline, MDA, phenolic, and flavonoid compounds. The application of treated Cd and Co solutions by A. pinnata showed a decrease in H2O2, proline, phenolic, and flavonoid compounds levels accompanied by a reduction in catalase and peroxidase activities compared to the control. This study showed the positive role of A. pinnata in alleviating the metal impacts, particularly Cd, on the seedling growth of wheat and its germination.
... Both BCF and TF are essential for assessing the feasibility of a plant Water 2023, 15, 797 6 of 18 species for phytoremediation purposes [51]. A BCF value of more than 1 demonstrates the potential success of a plant species for phytoremediation [52,53]. Plants with both BCF and TF values greater than 1 can be used as phytoextractors [54], whereas plants with a BCF value of greater than 1 and a TF value lower than 1 are phytostabilisers [55]. ...
Constructed wetlands are an affordable and reliable green alternative to conventional mechanical systems for treating domestic sewage. This study investigates the potential of 14 tropical wetland plant species for removing heavy metals from domestic sewage through the bioconcentration factor (BCF), translocation factor (TF), enrichment factor (EF), and geoaccumulation index (Igeo) using batch mesocosm studies. Plants with BCF > 1 and TF > 1 are classified as phytoextractors, while species with BCF > 1 and TF < 1 are phytostabilisers. The results indicate that 11 out of 14 species are magnesium phytostabilisers, 10 are calcium phytoextractors, and no plant species demonstrate ferrum phytoextraction properties. As for manganese phytoremediation, only three species depicted phytoextraction and phytostabilisation properties. The enrichment factor (EF) for all of the studied metals with ferum as a reference metal in all of the soil samples decreased after the phytoremediation of domestic sewage experiments, indicating depletion to mineral enrichment (EF < 2). All of the soil samples are generally classified as uncontaminated based on Igeo indices. Based on the factors and indices, it is suggested that the plants may have facilitated heavy metal removal from domestic sewage through uptake into the plant tissues from the roots.
... Pluchea indica is reported to have a high level of Cr accumulation in leaves and is thus considered a good phytoremediator (Kaewtubtim et al., 2018). The BCF value of Azolla caroliniana is 11 (Pandey, 2012), which makes it a good phytoremediator compared to Amaranthus dubius, which has a lower BCF value than 2 and a TF value of 1.1 (Mellem et al., 2012). The Cr accumulator plant species resist the toxic ions because of several cellular pathways such as phytochelatins production, compartmentalization of toxic ions, and phytosequestration (Shahid et al., 2017;Sinha et al., 2018;Chaudhary et al., 2018). ...
Chromium (Cr) is a naturally occurring, carcinogenic heavy metal that has become a pressing concern in recent decadesfor environmentalists. Due to high anthropogenic activities, the concentration of Cr has crossed the environmental threshold levels and consequently contaminated soil and water. The high solubility of Cr ions in the groundwater results in its high uptake by the plants leading to phytotoxicity and yield loss. The dearth of efficient and cost-effective treatment methods has resulted in massive chromium pollution. However, some phytoaccumulators capable of accumulating Cr in high amounts in their shoots and then performing their metabolic activity typically have bdseen identified. Chromium bioremediation using phytoaccumulators is very contemplative due to its eco-friendly and cost-effective outcome. These accumulators possess several mechanisms, such as biosorption, reduction, efflux, or bioaccumulation, naturally or acquired to counter the toxicity of Chromium. This review focuses on the detoxification mechanism of Cr by the phytoaccumulator species, theirresponses against Cr toxicity, and the scope for their application in bioremediation. Besides, Cr bioavailability, uptake, distribution, impairment of redox homeostasis, oxidative stress, and phytotoxicity imposed on the plants are also summarized. Further, the knowledge gap and prospects are also discussed to fill these gaps and overcome the problem associated with the real-time applicability of phytoaccumulator-basedbioremediation.
... Several nonessential and toxic HMs, as well as metalloids, i.e., arsenic (As), mercury (Hg), lead (Pb), cadmium (Cd), chromium (Cr), and aluminum (Al), are included in the top 20 priorities by the Agency for Toxic Substances and Disease Registry (ATSDR) (Rai et al., 2019;Ullah et al., 2015). Such HMs have a grave impact on aquatic and terrestrial environments, which enhance physiological impacts (Pandey, 2012). After entry into the human body through the food chain, HMs can result in diseases like chronic anemia, cardiovascular disease (Ullah et al., 2015), cognitive impairment (Iqbal, 2012), kidney impairment, and cancer (Wuana and Okieimen, 2011). ...
Heavy metals accumulation in wheat has become a severe menace to food security and human health. Proper understanding of the wheat response to metals stress and its management to minimize uptake may assist to enhance yield, grain quality, and growth. This chapter aims to highlight current updates about various mitigation approaches used to minimize metals uptake and phytotoxicity in wheat. Several agronomic and biological approaches have been studied which do hold a promise for obtaining desirable metals reduction in wheat grains. However, the selection of an appropriate method depends on various factors such as soil properties, type of metal, level of contamination, and environmental conditions. Among the available approaches, the use of low metal accumulating or metal-toxicity tolerant wheat varieties is the most efficient and eco-friendly method to ensure food safety and protect human health. Nevertheless, the applicability of this approach at the field level is undoubtedly necessary. This chapter aims to highlight the advancements in various mitigation approaches against heavy metals stress in wheat.
... It was also close to the result of the research with Azolla caroliniana, which was reported as a potential accumulator for heavy metals, that it had higher bioconcentration factors of 0.37-1.4 for various heavy metals [58]. In addition, the TF values of different heavy metals vary greatly among different plants. ...
The development of phytoremediation by garden plants is an effective way to deal with the dilemma of municipal sewage sludge disposal. In this study, two ornamental plants were used as phytoremediation plants to rehabilitate heavy-metal-contaminated municipal sewage sludge in field experiments, and the role of exogenous phytohormone IAA was also tested. Ornamental plants Loropetalum chinense var. rubrum (L. rubrum) and Rhododendron pulchrum (R. pulchrum) adapted well to the artificial soil made of municipal sewage sludge, and the concentrations of Cu, Zn, Pb, and Ni were decreased by 7.29, 261, 20.2, and 11.9 mg kg−1, respectively, in the soil planted with L. rubrum, and 7.60, 308, 50.1, and 17.7 mg kg−1, respectively, in the soil planted with R. pulchrum, accounted for 11–37% of the total amounts and reached significant levels (p < 0.05), except Cd. The concentration of Pb in all parts of the two ornamental plants was increased, as well as most heavy metals in L. rubrum root. As a result, three months after transplant, the phyto-extraction amounts in L. rubrum were 397, 10.9, and 1330 μg for Ni, Cd, and Pb, respectively, increased by 233% to 279%. The phyto-extraction amount in R. pulchrum were 1510, 250, and 237 μg for Zn, Pb, and Cu, respectively, increased by 143% to 193%. These results indicated a potential to remediate heavy metals of the two ornamental plants, especially L. rubrum. The results of correlation analysis implied that the interaction of heavy metals in the plant itself played an important role in the uptake of heavy metals. This seemed to explain why applying IAA in the experiment had little effect on plant growth and phytoremediation of heavy metals. This study provided a green and feasible idea for the proper disposal of municipal sewage sludge.
... Bioconcentration factor (BCF) values of all metals in root and frond ranged from 1.7 to18.6 and 1.8 to 11.0, respectively, which were greater than one and indicated the metal accumulation potential of Azolla caroliniana. Translocation factor (TF) ranged from 0.37 to 1.4 for various heavy metals (Pandey, 2012), and figure 3 shows heavy metals concentration in roots, fronds, and FA effluents. ...
Water is vital for humans and other living things, but water pollution has become a significant issue today. Various anthropogenic agricultural, industrial, and home activities produce multiple organic and inorganic substances dissolved or suspended in water. The goal of wastewater treatment is thus twofold: to reduce water pollution while also maintaining the water supply to demand. It is based on the three 3 Rs: reduce, reuse, and recycle. However, many of the methods used are ineffective or expensive. As a result, water purification is a matter of great interest. Eco-friendly approaches are essential among the new technologies and techniques tested in wastewater treatment. Aquatic macrophytes treat water by accumulating harmful metals and nutrients. Like water filters, a variety of aquatic floats can be suggested. Azolla is one among them, and it has been used for decades. Researchers have discovered that Azolla can reduce Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), nitrogen, phosphorus, and heavy metal concentrations in wastewater; therefore, it can be utilized for wastewater treatment. Azolla also produces a lot of biomasses in wastewater. The use of Azolla in reducing eutrophication in lakes and streams and other benefits is discussed in this study. According to the literature, Azolla has a high growth rate, with a doubling date of 2-4 days. Azolla's cell wall is composed of pectin, which has a high affinity for the adsorption of organic substances. Azolla serves as a "biofilter" during wastewater treatment in this way.
... After mowing, they form a dense plant cover, have a high anti-erosion potential, and their land biomass after drying is less flammable compared to other plants used for landscaping. They improve the microclimate, promote the absorption of carbon dioxide, increase biodiversity, and improve fertility [56,57]. ...
Soil and air pollution are main problems posing a serious threat to human health. Traditional physical and chemical soil remediation methods affect the soil ecosystem and are rather costly. Since the main purpose of soil remediation is not only to remove pollutants but also to restore soil health, the method of phytoremediation is becoming extremely relevant. Phytoremediation is an environmentally friendly and natural process of removing pollutants from the environment. Cleaning up contaminated sites and enabling re-use without harming future users requires the implementation of environmentally friendly and economically attractive technologies. Phytoremediation does not adversely affect the structure and biological life of the soil. Concerning on-site cleaning in situ. Hyperaccumulator plants can accumulate heavy metals from the soil, which is the so-called phytoextraction. The ability of trees and shrubs to effectively remove solid particles from the air has also been proven. However, it is not always possible to grow large plants in polluted areas. Therefore, the main goal of the research was to explore previous studies on the phytoremediation capability of herbaceous plants, in particular, their phytoextraction capacity. Another major issue was to study the main methods of improving plant phytoextraction. The results obtained show that grass can be a good solution for natural ecosystem cleanup. It is also necessary to pay attention to the impact of phytoextraction-improving substances on soil health.
... After mowing, they form a dense plant cover, have a high anti-erosion potential, and their land biomass after drying is less flammable compared to other plants used for landscaping. They improve the microclimate, promote the absorption of carbon dioxide, increase biodiversity, and improve fertility [56,57]. ...
Soil and air pollution are main problems posing a serious threat to human health. Traditional physical and chemical soil remediation methods affect the soil ecosystem and are rather costly. Since the main purpose of soil remediation is not only to remove pollutants but also to restore soil health, the method of phytoremediation is becoming extremely relevant. Phytoremediation is an environmentally friendly and natural process of removing pollutants from the environment. Cleaning up contaminated sites and enabling re-use without harming future users requires the implementation of environmentally friendly and economically attractive technologies. Phytoremediation does not adversely affect the structure and biological life of the soil. Concerning on-site cleaning in situ. Hyperaccumulator plants can accumulate heavy metals from the soil, which is the so-called phytoextraction. The ability of trees and shrubs to effectively remove solid particles from the air has also been proven. However, it is not always possible to grow large plants in polluted areas. Therefore, the main goal of the research was to explore previous studies on the phytoremediation capability of herbaceous plants, in particular, their phytoextraction capacity. Another major issue was to study the main methods of improving plant phytoextraction. The results obtained show that grass can be a good solution for natural ecosystem cleanup. It is also necessary to pay attention to the impact of phytoextraction-improving substances on soil health.
... Under heavy metal stress, Semane et al. (2010) discovered that the major subunit of RuBisCO-binding protein, proteins associated to oxygen evolution, PS I and II, and proteins related to oxygen evolution, all increased. Another proteome investigation of arsenic-stressed Anabaena species revealed that phytochelatins, which provide tolerance, were abundant (Pandey et al., 2012). ...
In earth heavy metals are an integral part, they can be both essential and nonessential. Soils polluted with heavy metals (HMs) have become common due to increase in geologic and anthropogenic activities. Significant environmental pollutants such as lead, nickel, cadmium, cobalt, and mercury cause plant toxic impact; reducing productivity and posing hazardous threats to agri-ecosystems are thus significant environmental pollutants. It affects the growth of plant due to phyto-toxicity. HMs interfere with the seed germination, growth of the plant and production mainly related to plant system physiology, biochemistry and genetic elements. HMs have a significant impact on seeds, cause defects and decrease germination by affecting the digestion and mobilization of food reserves in germinating seeds leads to seed toxicity and productivity loss. Accumulation of HMs is greatly influences the morphology of plants by cell degeneration and thickening of cell walls. It increases in the amount of treacherous elements in vascular cylinder and even ruptures the parenchyma tissue. HMs impede the action of important enzymes and obstruct the plant biochemical aspect like photosynthesis, pigment synthesis and most commonly the inhibit electron transport chain which contribute to the generation of radicals cause oxidative damage. It also decreases the vegetative growth of plants and increases the sign of senescence. In soil HMs levels cause osmotic disturbances in plants, they are known for effects on root growth, transport of water and transpiration. It alters the profile of genomic DNA and increase the rate of DNA methylation. To consider above facts, this chapter discussed the effects of HMs on important plant processes and tolerance through omics approaches.
... Bioconcentration factor (BCF) values of all metals in root and frond ranged from 1.7 to18.6 and 1.8 to 11.0, respectively, which were greater than one and indicated the metal accumulation potential of Azolla caroliniana. Translocation factor (TF) ranged from 0.37 to 1.4 for various heavy metals (Pandey, 2012), and figure 3 shows heavy metals concentration in roots, fronds, and FA effluents. ...
Water is vital for humans and other living things, but water pollution has become a
significant issue today. Various anthropogenic agricultural, industrial, and home activities
produce multiple organic and inorganic substances dissolved or suspended in water. The
goal of wastewater treatment is thus twofold: to reduce water pollution while also
maintaining the water supply to demand. It is based on the three 3 Rs: reduce, reuse, and
recycle. However, many of the methods used are ineffective or expensive. As a result,
water purification is a matter of great interest. Eco-friendly approaches are essential
among the new technologies and techniques tested in wastewater treatment. Aquatic
macrophytes treat water by accumulating harmful metals and nutrients. Like water filters,
a variety of aquatic floats can be suggested. Azolla is one among them, and it has been
used for decades. Researchers have discovered that Azolla can reduce Chemical Oxygen
Demand (COD), Biochemical Oxygen Demand (BOD), nitrogen, phosphorus, and heavy
metal concentrations in wastewater; therefore, it can be utilized for wastewater treatment.
Azolla also produces a lot of biomasses in wastewater. The use of Azolla in reducing
eutrophication in lakes and streams and other benefits is discussed in this study.
According to the literature, Azolla has a high growth rate, with a doubling date of 2-4
days. Azolla's cell wall is composed of pectin, which has a high affinity for the adsorption
of organic substances. Azolla serves as a "biofilter" during wastewater treatment in this
way.
In recent times, increased geogenic and human-centric activities have caused significant heavy metal(loid) (HM) contamination of soil, adversely impacting environmental, plant, and human health. Phytoremediation is an evolving, cost-effective, environment-friendly, in situ technology that employs indigenous/exotic plant species as natural purifiers to remove toxic HM(s) from deteriorated ambient soil. Interestingly, the plant’s rhizomicrobiome is pivotal in promoting overall plant nutrition, health, and phytoremediation. Certain secondary metabolites produced by plant growth-promoting rhizobacteria (PGPR) directly participate in HM bioremediation through chelation/mobilization/sequestration/bioadsorption/bioaccumulation, thus altering metal(loid) bioavailability for their uptake, accumulation, and translocation by plants. Moreover, the metallotolerance of the PGPR and the host plant is another critical factor for the successful phytoremediation of metal(loid)-polluted soil. Among the phytotechniques available for HM remediation, phytoextraction/phytoaccumulation (HM mobilization, uptake, and accumulation within the different plant tissues) and phytosequestration/phytostabilization (HM immobilization within the soil) have gained momentum in recent years. Natural metal(loid)-hyperaccumulating plants have the potential to assimilate increased levels of metal(loid)s, and several such species have already been identified as potential candidates for HM phytoremediation. Furthermore, the development of transgenic rhizobacterial and/or plant strains with enhanced environmental adaptability and metal(loid) uptake ability using genetic engineering might open new avenues in PGPR-assisted phytoremediation technologies. With the use of the Geographic Information System (GIS) for identifying metal(loid)-impacted lands and an appropriate combination of normal/transgenic (hyper)accumulator plant(s) and rhizobacterial inoculant(s), it is possible to develop efficient integrated phytobial remediation strategies in boosting the clean-up process over vast regions of HM-contaminated sites and eventually restore ecosystem health.
Molecular and Physiological Insights into Plant Stress Tolerance and Applications in Agriculture Part 2 is an edited volume that presents research on plant stress responses at both molecular and physiological levels. This volume builds on the previous volume to provide additional knowledge in studies on the subject.
Key Features
- Explains aspects of plant genetics central to research such as the role of cytosine methylation and demethylation in plant stress responses, and the importance of epigenetic genetics in regulating plant stress responses.
- Explores how Late Embryogenesis Abundant proteins affect plant cellular stress tolerance with an emphasis on their molecular mechanisms and potential implications.
- Focuses on beneficial microorganisms including rhizobacteria, endophytes, and mycorrhizal fungi, which are expected to be alternative fertilizers with the advantages of being cost-effective, toxin-free, and eco-friendly.
- Highlights the potential use of endophytic bacteria for protecting crops against pathogens
- Presents an in-depth analysis of the molecular level to understand the impact of ATP-binding cassette transporters on plant defense mechanisms with a discussion of the potential anti-pathogenic agents based on terpenes and terpenoids.
The content of the book is aimed at addressing UN SDG goals 2, 12, and 15 to achieve zero hunger and responsible consumption and production, and to sustainable use of terrestrial ecosystems, respectively.
This comprehensive resource is suitable for researchers, students, teachers, agriculturists, and readers in plant science, and allied disciplines.
Microalgae and cyanobacteria produced abundant high-valued bioproducts in small arable land in a short time. The bioproducts range from their biomass for food, feed, and biofuels to extractable fine bioproducts. The growing market and techno-economical aspect support the viability of this biomass production. Microalgae and Cyanobacteria are also highly diverse thus progression of its current usage in biomass production served as a challenge of its own but also an opportunity. In this book chapter, progression in cultivating and screening of technologies on bioprocess engineering of microalgae and cyanobacteria will be discussed with their high-demands on food, feed, and energy industry. This chapter further discusses the advance and manufacturer of different valuable bioproducts through technologies and production platforms for Microalgae and Cyanobacteria.
As the science got advanced, breeders started using genotype, metabolites, nutrient profiles as well as omics technology for developing desired genotypes. Both vertical and horizontal gene transfer are being widely used for transferring genes of interest to the target genotype. Crop breeding is contributing greatly to secure nutrition, to improve human health and environment. In addition to conventional breeding, advancement in biotechnology and omics technologies have successfully identified several candidate genes for nutritional and environmental security. Such genes are now successfully introduced in target crops, and has contributed to eliminate poverty, malnutrition and environmental pollution and to improve overall ecosystem including human health. Several biotech crops like tobacco, soyabean, Brassica spp., and Bt-crops are developed for pollution control of soil, water, metal toxicity and agrochemical pollution whereas several weed species like waterweed, duckweed have been identified to detoxify explosive, aquatic and oil spill pollutants. Although the merits of existing genetically modified crops can be debated, their role for increased food production, resistance towards biotic and abiotic stresses, resistance towards toxic effects of agrochemicals and reduction in the emission of environmental pollutant gases has significantly contributed in ensuring global food, nutrition and environmental security. More focus is necessary on breeding crops considering nutritional, health and environmental aspects.
Percolation of toxic metals existing in fly ash is the prime source of subterranean water contamination in the locale areas near industrial units. In this regard, a field survey was done in the vicinity of Rosa Thermal Power Plant situated in the Shahjahanpur district of Uttar Pradesh, India to examine the natural vegetation particularly aquatic ferns growing naturally in fly ash (FA) contaminated water bodies. It was observed that four aquatic ferns namely Marsilea minuta, Salvinia molesta, Ceratopteris thalictroides, and Azolla filiculoides were growing in the target site in which Azolla biomass has been found enduring and flourishing dominantly near the banks of Garrah River adjoining to the thermal power plant. The result of physicochemical studies of FA polluted water bodies revealed that the concentration of Cd, Cr, Pb, Al, Ni, Si, Mn, and Cu were 42.3, 41.1, 40.1, 4615, 204, 5600, 70 and 58.6 (μg/g) which are significantly high in comparison to the control (reference) site in which Cd, Cr, Pb, Al and Si are below detection limit and Ni, Mn, and Cu were 23.8, 45.8 and 25.4 (μg/g) respectively. Similarly, the metal content of collected Azolla filiculoides was significantly higher than the control site. Metal content (μg/g) in Azolla was found according to following pattern: Fe (61400) ˃ Si (9400) ˃ Cr (7900) ˃ Ni (6100) ˃ Cu (5600) ˃ Pb (4900) ˃ Zn (4600) ˃ Al (3800) > Mn (3200) > Cd (2700) > B (1100). The total chlorophyll was heavily decreased by 58.33 (%) in FA contaminated site in comparison to the control site. The result of antioxidant enzymes like MDA, SOD, and GPX was found to increase by 73.38 (%), 47.56 (%), and 80.75 (%) respectively in Azolla biomass growing in polluted water bodies due to the generation of oxidative damage by free radicals. However, the plant was not showing any visual phytotoxic symptoms. Therefore, it indicates that the Azolla filiculoides has the capability to withstand FA-induced metal toxicity and it may prove an ideal candidate to detoxify FA-contaminated water bodies.
Graphical Abstract
Phytoremediation of benzotriazoles (BTR) from waters by floating macrophytes is not well understood, but it seems to have the potential to be used in conjunction with conventional wastewater treatment plants. The effectiveness of removing four compounds from the benzotriazole group by floating plants Spirodela polyrhiza (L.) Schleid. And Azolla caroliniana Willd. From the model solution, was studied. The observed decrease in the concentration of studied compounds was in the range 70.5%-94.5% using S. polyrhiza, and from 88.3% to 96.2% for A. caroliniana. It was determined using chemometric methods that the effectiveness of the phytoremediation process is mainly influenced by three parameters: exposure time to light, pH of the model solution and the mass of plants. Using the design of experiments (DoE) chemometric approach, the optimal conditions for removing BTR were selected: plant weight 2.5 g and 2 g, light exposure 16 h and 10 h, and pH 9 and pH 5 for S. polyrhiza and A. caroliniana, respectively. Studies on the mechanisms of BTR removal have shown that the reduction in concentration is mainly due to the process of plant uptake. Toxicity studies have proved that the tested BTR affected the growth of S. polyrhiza and A. caroliniana and induced changes in the levels of chlorophyllides, chlorophylls as well as carotenoids. More dramatic loss in plant biomass and photosynthetic pigment contents was observed in A. caroliniana cultures exposed to BTR.
Iron (Fe) is an essential micronutrient for all organisms because it plays a significant role in metabolic processes (e.g., photosynthesis, respiration, and DNA synthesis), and many metabolic pathways are activated by Fe. Globally, Fe deficiency is a serious health concern due to the consumption of low-iron diets (or plant-based diets). Fe deficiency in humans induces severe diseases such as anemia. Considering the importance of Fe for the development of both humans and plants, this chapter reports some of the recent advancements in nano-fertilizer for improving crop quality and subsequent human intake to alleviate the Fe deficiency. Furthermore, synthesis methods of Fe-based-NPs, e.g., chemically and bio-synthesis are discussed in details alongside advanced characterization techniques. Exposure of Fe-based nanomaterials via control release systems can enhance crops’ growth and nutritional content. Present chapter indicated that Nano-enabled technologies could be beneficial for reducing the dependence on chemical fertilizers and solving the Fe deficiency problem. The application of Fe-based nano fertilizers can prove to be a sound and sustainable approach to achieve the goal of increasing micronutrient content and crop yield. Fe-based nano fertilizers can bring nutrient-rich crops with economic advantages if the products are environmentally and economically sustainable.KeywordsIron based nanoparticlesPlant healthToxicityDefensive mechanism
Global agricultural production is facing a lot of challenges. The current agricultural practices seems to be incompetent to meet the global food demands. The increasing health and environmental concerns have also put forward the challenge of attaining global food production in a sustainable manner. The synergistic interactions between different nanoparticles (NPs) and Plant Growth Promoting Rhizobacteria (PGPR) have put forward the novel way of improving plant health and increasing its productivity. Different metal and metal oxide NPs like silver, gold, zinc, titanium dioxide, zinc oxide and iron oxide are known to interact with different PGPR in a synergistic manner. These interactions increase the functioning of microbial partner by improving its plant growth promotion traits. The co-inoculation of NPs with their microbial synergist can be utilized to increase the plant health and productivity during plant exposure to different stresses like salinity stress, heat stress, drought stress, and heavy metal stress. The plant-microbe interaction facilitated by NPs activate the plant defense systems, increase the activity of antioxidant enzymes in plants, and trigger the accumulation of protective solutes like proline and glutathione that increase the plant health and productivity during stressful conditions. In addition, this combinatorial approach can also be utilized for bio fortification of plants.KeywordsNanoparticlePGPRRhizosphereNanoparticle-PGPR InteractionsPlant-Microbe Interactions
Aluminum, being the most abundant metal on earth, has applications in diverse fields. To utilize the benefits of aluminum completely, aluminum oxide nanoparticles (NPs) are synthesized and administered on plants because they are the connecting link between the environment and human health. The effect of aluminum oxide NPs on a variety of plant species to check their interaction, uptake, and translocation is analyzed in this chapter. Aluminum oxide NPs’ phytotoxicity is determined by their absorption, transport, and accumulation in plants. Interestingly, the administration of aluminum oxide NPs at different concentrations resulted in a significant effect on root elongation, shoot elongation, seed germination, as well as macro and micronutrient uptake. This chapter has mostly addressed nanoparticle interactions in plants, including their absorption, mobilization, and metabolic effects. We also looked into NPs’ potential to protect plants and control stress under a variety of adverse settings. Aluminum oxide NPs’ effects on the four enzymatic antioxidants namely CAT, POD, SOD, and APX are compared, to examine their effect on different plant species. This chapter will assist researchers in comprehending nanotechnology in combination with agriculture, allowing them to build specialized NPs to meet agricultural needs sustainably.KeywordsAluminum oxide nanoparticlesAntioxidant enzymesReactive oxygen species
The use of nanotechnology applications for the improvement of agriculture sectors is increasing day by day. Relative to conventional fertilizers, nano-fertilizers are promptly uptaken by plants and can enhance the plant's growth and development more efficiently. Thus, nanomaterials i.e. nanofibers, nano-fertilizers, and nano-pesticides can remarkably enhance the plants growth and yield production as well as disease resistance with limiting pathogenic attacks. Plant growth-promoting rhizobacteria (PGPR) are deliberated as beneficial soil bacteria which can boost the plants growth attributes in both direct and indirect ways. These bacteria can restrict the harmful impacts of chemical fertilizers as well as toxic compounds released in the soil as a result of industrialization. The inoculation of PGPR can be proved as an efficient technique to enhance the productivity of the agriculture sector with an environmentally friendly approach. The combined application of nanomaterials and PGPR could be a promising way to maintain crop development and productivity. Additionally, various nanomaterials such as titanium, gold, zeolites, carbon, zinc, silver, silica, etc. with PGPR have an auspicious effect on plant development. This book chapter will explore the novel combined strategy of nanotechnology and PGPR to promote crop productivity.KeywordsNanoparticlesPGPRPlant growth stimulationDevelopmentResponse
Intensive industrial activities increased the concentration of chromium in the environment especially in the soil and water, which pose serious threat due to its cytotoxic and carcinogenic nature. Phytoremediation has evolved as an eco-friendly, cost-effective alternative for the decontamination of pollutants, and an attempt has been made to reveal the potential of Cr remediation by an invasive plant, Alternanthera tenella Colla in the present study. The morphological, anatomical and physiological modifications of plant tissues in response to 240 µM of K 2 Cr 2 O 7 is studied, with reference to the elemental distribution pattern and bioaccumulation potential. Assessment of growth parameters showed that Cr adversely affects the elongation of root and shoot, leaf area, and dry biomass weight. Cr influence the macro and micro-elemental distribution in plant tissues specially in roots and leaves. Plants exhibited structural modifications like increase in the thickness and diameter of the xylem walls in the root, stem and leaf tissues of Cr treated A. tenella . Presence of cell structural distortions and Cr deposit inclusions in the xylem wall and the inner parenchyma cells were distinct. Cr stress induced the reduction in pigment content and metabolites like proteins and soluble sugars, while proline, phenol and malondialdehyde marked a significant increase. With BCF and TF values greater than 1 and the mechanisms to cope with the metal stress, A. tenella proves to be an ideal candidate for phytoextraction of Cr.
Heavy metals (HMs) entered in water due to industrial activities like mining, glass, fertilizer, paper, textile, Pharmaceuticals production and others. These HMs in water above threshold level are toxic and affects soil fertility and crop productivity. HMs are biologically magnified in the upper trophic levels and pose risk to animal and human health. Removal of these HMs with growing plants in affected water/soil (phytoremediation) is an ecologically and economically effective method. These plants capable of absorbing, immobilizing, extracting, and degrading HMs. Phytoremediation capacity of the plants can be increase with the application of new researches related to process including biotechnology and genetic engineering. Present review describe the mechanism of phytoremediation, its suitable plants and recent development in the technology to enhance the removal capacity of plants for HMs, along with proper disposal methods of the harvested biomass, to prevent entry of the HMs in the food chain. To reduce the risk of HMs toxicity in water/ soil/crop and low cost biomass disposal, it is necessary to popularise the method with scientific knowledge.
Among the largest known environmental pollutants, fly ash generated as by product from combustion of coal is one of them. It is one of the well-known complex anthropogenic substances, whose indecorous dumping turns out to be a huge environmental concern. Due to the presence of some toxic heavy metals and metalloids like Cr, Zn, Mn, Pb, As, etc., fly ash remains unused to quite an extent and its disposal practice still remains a debatable issue. Search for microbial species which ensure heavy metal resistant property and also have potential in plant growth promotion is essential for fly ash management. Microbes have been observed to excrete organic acids, enzymes, siderophores and protons, to increase metal mobilization, and phytoextraction from dumping site of fly ash. The present chapter provides detailed information relating to fly ash with respect to its properties, generation, utilization, problems due to improper disposal, and main concern to microbe assisted fly ash management.
Globally, the rapid development in industrialization and urbanization is the primary cause of the rising pollution problem. Because of population growth and agricultural reliance, the earth's finite natural freshwater resources will be under severe strain until 2030. The conservation of the environment necessitates a well-thought-out strategy for removing or mitigating the contaminants’ reversible and irreversible effects. The conventional technologies are energy-intensive, had high maintenance and operation costs, provided insufficient treatment, along with the production of ecologically toxic sludge/wastes. Phytoremediation technology has piqued the interest of many academics across the world as an environmentally friendly clean-up option with various advantages over traditional approaches. It can also be used to recover valuable metals and can be used for the production of renewable energy. This chapter will explore the application of integrating phytoremediation of aquatic pollution with energy and element recovery as well as other ecological services. The problems associated with the application of these technologies and future prospects are also comprehensively discussed.
Drainage water in developing countries has a high abundance of pathogenic bacteria and high levels of toxic and mutagenic pollutants. Remediation of drainage water is important in water-poor counties, especially with the growing need to secure sustainability of safe water resources to fulfill increasing demands for agriculture. Here, we assess the efficiency of macrophyte Pistiastratiotes to remediate a polluted drain in Egypt, rich in macronutrients, heavy metals, and different types of pathogenic and non-pathogenic bacteria. Drainage water was sampled monthly, for a year, to assess seasonal changes in bacterial abundance, water physicochemical properties (transparency, temperature, dissolved oxygen, EC, pH, N, P, and K), and heavy metals contents (Pb, Zn, and Co) in a polluted drain dominated with P.stratiotes. The ability of P.stratiotes to rhizofiltrate the three heavy metals was calculated. The results showed seasonal variations in the plant rhizofiltration potential of Co and Salmonella abundance. The highest values of dissolved oxygen (12.36 mg/L) and macronutrient elements (N and P) were attained in the winter. The counts of total coliform, fecal coliform, fecal streptococci, and in Salmonella spp. were the highest in the summer. P.stratiotes accumulated Pb more than Zn and Co. The highest levels of rhizofiltration were in summer for Pb and Co and in the autumn for Zn. Canonical correspondence analysis (CCA) showed that the variation in the bacterial abundance and plant rhizofiltration potential was strongly and significantly affected by water-dissolved oxygen. Moreover, the rhizofiltration potential of Pb and Co showed a positive correlation with water N. Overall, P.stratiotes could be proposed as a potential biomonitor for heavy metals in polluted water.
Heavy metals constitute a serious health risk because they accumulate in soils, water and organisms. One of the methods of removing these pollutants from water and soil is the use of plants (phytoremediation). There are many plants (hyperaccumulators) which have the ability to accumulate large amounts of heavy metals. One of them is the aquatic fern Azolla sp., which can bind some substances. The aim of this study was to verify the ability of Azolla caroliniana Willd. (Azollaceae) to fix Pb and Cd from polluted waters. During the experiment, A. caroliniana was grown in water solution enriched in Pb(II) and Cd(II), each at concentrations of 0.1, 0.5 and 1 mg dm-3. The presence of lead and cadmium ions caused an inhibition of A. caroliniana growth by about 30-37 and 24-47%, respectively. After the end of the experiment, the content of the metals tested was determined in the medium and in the biomass (after mineralization). In the water medium, the decrease of Pb(II) amounted to 90% and that of Cd(II) to 22%. In the A. caroliniana tissues, the content of lead was up to 416 mg Pb per kg d.m., and that of cadmium – up to 259 mg Cd per kg d.m.
Study was conducted on six different Azolla species, available in the germplasm collection of NCCUBGA, IARI, New Delhi namely A. filiculoides, A. mexicana, A. microphylla, A. pinnata, A. rubra and A. caroliniana in a polyhouse to assess their growth potential by determining their maximal biomass productivity, doubling time and relative growth rates. Their nitrogen fixing potential was assessed by acetylene reduction assay. Among them Azolla microphylla gave highest biomass production and relative growth rate followed by Azolla caroliniana. Both these had high nitrogenase activity also. Peak nitrogenase activity of these strains was found on 14th day of growth and it declined on further incubation. Azolla microphylla and Azolla rubra were more tolerant to salinity than others. On the other hand Azolla pinnata, which is endemic species found in India, exhibited low biomass production, relative growth rate and lower nitrogenase activity compared to other species. It was unable to sustain growth in saline medium. Under polyhouse conditions, A. microphylla was found to perform better than other cultures in terms of biomass productivity, N fixing ability and salt tolerance. Hence it is taken up for mass production.
Sedum alfredii Hance has been identified as a new zinc (Zn) hyperaccumulating plant species. In this study, the effects of cadmium (Cd) supply levels (control, 12.5, 25, 50, 100, 200, 400, 800molCdL–1) on the growth and cadmium accumulation and Zn supply on Cd accumulation in S.alfredii Hance were studied. The results showed that no reduction in shoot and root dry matter yields were noted when the plants were grown at Cd supply levels up to 200molL–1 in nutrient solution. Slight stimulation on shoot growth was noted at relatively low Cd levels (25 to 100molL–1). Cadmium concentrations in leaves and stems increased with increasing Cd supply levels, and reached a maximum of approximately 9000 and 6500mgkg–1 (DW) at 400molCdL–1, respectively. Root Cd concentration increased sharply only at relatively high Cd levels. Cadmium distribution in different parts of the plant was in the order: leaf > stem root. The amount of Cd accumulated in the shoots reached 2.9 and 3.2mg plant–1 at external Cd levels of 200 and 400molL–1, respectively. The shoot/root Cd ratios were greater than 2 and more than 95% of the total Cd taken up by S.alfredii was translocated to the shoots at the external Cd levels 200molL–1. The concentrations of P, Ca, Mg, B, Fe, Mn, Cu, and in the shoots and roots were influenced differentially by Cd treatments. High Zn supply (500molL–1) enhanced Cd concentrations in the leaves and stems at the Cd levels 100molL–1, and root Cd concentration at the Cd levels 50molL–1. These results indicate that S.alfredii has an extraordinary ability to tolerate and hyperaccumulate Cd and this is the first report of the new Cd hyperaccumulator S.alfredii Hance. The finding of Cd/Zn hyperaccumulation in S.alfredii Hance provides an important plant material for understanding the mechanisms of Cd/Zn co-hyperaccumulation and for phytoremediation of the heavy metal contaminated soils.
The aim of the present work was to monitor the Hg pollution in water and sediments of G.B. Pant Sagar located in Singrauli
Industrial Region, India and to suggest the efficient aquatic plants for its phytoremediation. The study assessed the comparative
potential of a free floating water fern Azolla pinnata and submerged aquatic macrophyte Vallisneria spiralis to purify waters polluted by Hg. Six days laboratory experiments have been conducted to mark the percentage removal of Hg
at initial concentration of 0.1, 0.5, 1.0 and 3.0mg L−1. The percentage removal of Hg was higher for A. pinnata (80–94%) than V. spiralis (70–84%). Likewise, the Hg accumulated in dry mass was much higher for A. pinnata and a high correlation (R
2 = 0.91 for A. pinnata and 0.99 for V. spiralis) was obtained between applied Hg doses and accumulated amounts in biomass. A concentration dependent decrease in chlorophyll
a, protein, RNA, DNA and nutrients (NO3− and
\textPO\text4\text3 - {\text{PO}}_{\text{4}}^{{\text{3 - }}}) uptake was detected in A. pinnata and V. spiralis due to Hg toxicity. The decrease was more prominent in Azolla than Vallisneria. The results recommended the use of A. pinnata and V. spiralis to ameliorate the industrial effluents (thermal power, chlor-alkali and coal mine effluent) contaminated with Hg.
Aquatic macrophytes play an important role in the structural and functional aspects of aquatic ecosystems by altering water movement regimes, providing shelter to fish and aquatic invertebrates, serving as a food source, and altering water quality by regulating oxygen balance, nutrient cycles, and accumulating heavy metals. The ability to hyperaccumulate heavy metals makes them interesting research candidates, especially for the treatment of industrial effluents and sewage waste water. The use of aquatic macrophytes, such as Azolla with hyper accumulating ability is known to be an environmentally friendly option to restore polluted aquatic resources. The present review highlights the phytoaccumulation potential of macrophytes with emphasis on utilization of Azolla as a promising candidate for phytoremediation. The impact of uptake of heavy metals on morphology and metabolic processes of Azolla has also been discussed for a better understanding and utilization of this symbiotic association in the field of phytoremediation.
The lichen diversity assessment carried out around a coal-based thermal power plant indicated the increase in lichen abundance with the increase in distance from power plant in general. The photosynthetic pigments, protein and heavy metals were estimated in Pyxine cocoes (Sw.) Nyl., a common lichen growing around thermal power plant for further inference. Distributions of heavy metals from power plant showed positive correlation with distance for all directions, however western direction has received better dispersion as indicated by the concentration coefficient-R(2). Least significant difference analysis showed that speed of wind and its direction plays a major role in dispersion of heavy metals. Accumulation of Al, Cr, Fe, Pb and Zn in the thallus suppressed the concentrations of pigments like chlorophyll a, chlorophyll b and total chlorophyll, however, enhanced the level of protein. Further, the concentrations of chlorophyll contents in P. cocoes increased with the decreasing the distance from the power plant, while protein, carotenoid and phaeophytisation exhibited significant decrease.
The level of heavy metal pollution in Singrauli, an industrial region in India, was assessed and the phytoremediation capacity of a small water fern, Azolla pinnata R.BR (Azollaceae), was observed to purify waters polluted by two heavy metals, i.e., mercury (Hg) and cadmium (Cd) under a microcosm condition. Azolla pinnata is endemic to India and is an abundant and easy-growing free-floating water fern usually found in the rice fields, polluted ponds, and reservoirs of India. The fern was grown in 24 40-L aquariums containing Hg2+ and Cd2+ ions each in concentrations of 0.5, 1.0, and 3.0 mgL(-1) during the course of this study. The study revealed an inhibition of Azolla pinnata growth by 27.0-33.9% with the highest in the presence of Hg (II) ions at 0.5 mgL(-1) in comparison to the control After 13 days of the experiment, metal contents in the solution were decreased up to 70-94%. In the tissues of Azolla pinnata, the concentration of selected heavy metals during investigation was recorded between 310 and 740 mgKg(-1) dry mass, with the highest levelfoundfor Cd (II) treatment at 3.0 mgL(-1) containing a metal solution.
Here, we examined the effectiveness of two approaches for reducing cadmium (Cd) accumulation in durum wheat (Triticum turgidum L. var durum) grain: the application of supplemental zinc (Zn), and the use of cultivars exhibiting reduced grain Cd concentrations. Two durum wheat near-isogenic lines (NIL) that differ in grain Cd accumulation were grown to maturity in solution culture containing a chelating agent to buffer the free activities of Zn and Cd at levels approximating those of field conditions. The low Cd accumulating (L-Cd) isoline had Cd concentrations, in grains and shoot parts, which were 60-70% lower than those of the high Cd accumulating (H-Cd) isoline. Increasing the Zn activities in the nutrient solution from deficient to sufficient levels reduced the concentration of Cd in grains and vegetative shoot parts of both isolines. The results suggest that supplemental Zn reduces Cd tissue concentrations by inhibiting Cd uptake into roots. Cd partitioning patterns between roots and shoots and between spike components suggest that the physiological basis for the low Cd trait is related to the compartmentation or symplasmic translocation of Cd.
The plants of Sesbania cannabina Ritz grown on different amendments of fly ash (FA), have shown a high accumulation of metals (Fe, Mn, Zn, Cu, Pb and Ni). The highest accumulation of Fe the and lowest level of Ni were recorded in these plants. The different amendments of fly ash with garden soil (GS) were extracted with DTPA and the levels of metals were found to be decreased with an increase in fly ash application ratio from 10% to 50% FA. The analysis of the results showed an increase in the level of malondialdehyde (MDA) content of the roots for all the exposure periods. The maximum increases of 136% (roots) and 120% (leaves) were observed in MDA content at 100% FA after 30 d of growth of the plant, compared to GS. The level of antioxidants was found to increase for all the exposure periods in the roots of the plants to combat metal stress. At 30 d, the maximum increase of 57% (ascorbic acid) and 78% (free proline) was observed in the roots of the plants grown on 100% and 10% FA, respectively, as compared to their respective GS. At 90 d, a maximum increase of 42% (cysteine) and 117% (NPSH) was recorded in the roots of the plants grown on 25% and 100% FA, respectively, as compared to their respective GS. In leaves, a significant increase in antioxidants i.e. cysteine, NPSH and free proline content was recorded after 30 d, whereas no such trend was observed for the rest of the exposure periods. The chlorophyll and carotenoid contents increased with an increase in the FA amendment ratio from 10% to 50% FA for all the exposure periods as compared to GS. In both roots and leaves, the level of protein content increased in all the amendments and 100% FA at 30 d as compared to GS. Thus, there is a balance in the level of MDA content and level of antioxidants in the plants at 90 d. In view of its tolerance, the plants may be used for phytoremediation of metals from fly ash contaminated sites and suitable species for plantation on fly ash land fills.
A pilot scale study was conducted to find out the different forms of metals if fly ash (FA) and bioaccumulation of these metals in the naturally growing vegetation on FA dumps. The total, acid extractable, bioavailable and water soluble fraction of metals of Fe, Cu, Mn, Zn, Ni, Co and Pb, and their bioaccumulation coefficients (BAC) on naturally growing vegetation were determined. FA samples had a neutral pH, low electrical conductivity, low organic C and trace amounts of N and P. The relative abundance of total metals in FA were found in the order Fe >Mn >Zn >Ni >Co>Cu. The concentration of bioavailable (DTPA) metals depend on the type and nature of coal used in thermal power stations. In the water the extract solution, only Fe and Zn were found above detection limits. After one year only four species of naturally occurring herbaceous vegetation were found growing and Cynodon dactylon (grass) covered almost entire surface of the FA. Iron accumulated to the greatest extent in vegetation followed by Mn, Zn, Cu, Pb, Ni and Co. The sequence of BAC for different metals were Fe (202)>Mn(90)>Zn (63)>Pb(49)>Ni(41)>Cu(24). The experimental study revealed that Cynodon grass could be used for remediation of fly ash without any amendments, as this grass species act as metal excluder type.
This is the 5th edition of a well-established book Principles of Plant Nutrition which was first published in 1978. The same format is maintained as in previous editions with the primary aim of the authors to consider major processes in soils and plants that are of relevance to plant nutrition.This new edition gives an up-to-date account of the scientific advances of the subject by making reference to about 2000 publications. An outstanding feature of the book, which distinguishes it from others, is its wide approach encompassing not only basic nutrition and physiology, but also practical aspects of plant nutrition involving fertilizer usage and crop production of direct importance to human nutrition. Recognizing the international readership of the book, the authors, as in previous editions, have attempted to write in a clear concise style of English for the benefit of the many readers for whom English is not their mother tongue. The book will be of use to undergraduates and postgraduates in Agriculture, Horticulture, Forestry and Ecology as well as those researching in Plant Nutrition.
Chromium, copper, cadmium, lead, nickel, iron and zinc contents of a lichen species (Pyxine subcinerea Stirton) and mango bark collected from 12 sites in Haridwar city (Uttarakhand) were compared with soil, sampled from beneath the tree from which lichens were collected. The metal contents in lichen, bark and soil ranged from 1,573 to 18,793, 256 to 590 and 684 to 801 μg g−1, respectively. This clearly indicates that lichens accumulated higher amounts of metal compared to bark or soil. Statistical analysis revealed that metal concentration in lichens did not show significant linear correlation with the bark or soil. Pearsons correlation coefficients revealed negative correlation of Pb (r = −0.2245) and Ni (r = −0.0480) content between lichen and soil, which indicate direct atmospheric input of metals from ambient environment. Quantification and comparison of elemental concentration in lichens, its substratum and soil can provide valuable information about air quality in the collection area.
Increasing areas of coal fly ash (FA) deposit pose a serious concern for its safe disposal to maintain the environment quality. Several thousand hectares of land have been occupied for the storage of FA all over the world. FA deposits cause serious environmental pollution through wind erosion and ground water contamination through leaching process. Naturally growing Saccharum munja on the derelict FA lagoons of NTPC Unchahar, India was identified as a native perennial grass in the rehabilitation process. We tested its ecological suitability for the effective restoration of FA lagoons in terms of their abundance and stabilization. The FA contains alkaline pH, and low organic C coupled with toxic metals i.e. Fe, Cd, Cr, Cu, Mn, Ni, Pb and Zn. The concentrations of these metals in different parts of the plant fall in the average range of plants and were found within toxic limits. Natural colonization of S. munja predominate in the areas of FA deposits with fast growth and high biomass which is used by local people for making ropes, baskets, mats, huts, etc. to support their livelihood. These results suggest that S. munja would be potentially useful to rehabilitate the FA dumps more efficiently if it is introduced properly on fresh lagoons to convert barren FA deposits into ecologically and socio-economically productive habitats without any inputs or maintenance.
Azolla, which is an aquatic fern, has proved to be effective in the uptake and accumulation of metals from polluted waters. Azolla spp., namely A. microphylla cv. MH3 and A. caroliniana Willd, were chosen as model plants so that Cd(II) could be accumulated from aqueous solution. An increase in uptake time and the concentration of Cd(II) in aqueous solution resulted in more Cd(II) accumulation in both species. Modified Michaelis–Menten equation was employed to describe the concentration-dependent kinetics of Cd(II) uptake through the roots of A. microphylla cv. MH3, and the values of Km and Vmax were found to be 0.23mg/L and 16.49μg/(g.f.wt.h), respectively. Cd(II) uptake by A. microphylla cv. MH3 occurs partly through Ca(II) channels and has the potential to be mediated by Zn(II) transporters.
The present article briefly describes the concerns regarding the suitability of Vigna radiata L. for the revegetation of fly ash landfills.
Phytoremediation is an integrated multidisciplinary approach to the cleanup of contaminated soils, which combines the disciplines of plant physiology, soil chemistry, and soil microbiology. Metal hyperaccumulator plants are attracting increasing attention because of their potential application in decontamination of metal-polluted soils. Traditional engineering technologies may be too expensive for the remediation of most sites. Removal of metals from these soils using accumulator plants is the goal of phytoremediation. The emphasis of this review has been placed on chromium (Cr), plutonium (Pu), and uranium (U). With the exception of Cr, these metals and their decay products exhibit two problems, specifically, radiation dose hazards and their chemical toxicity. The radiation hazard introduces the need for special precautions in reclamation beyond that associated with non-radioactive metals. The uptake of beneficial metals by plants occurs predominantly by way of channels, pores, and transporters in the root plasma membrane. Plants characteristically exhibit a remarkable capacity to absorb what they need and exclude what they don`t need. But most vascular plants absorb toxic and heavy metals through their roots to some extent, though to varying degrees, from negligible to substantial. Sometimes absorption occurs because of the chemical similarity between beneficial and toxic metals. Some plants utilize exclusion mechanisms, where there is a reduced uptake by the roots or a restricted transport of the metal from root to shoot. At the other extreme, hyperaccumulator plants absorb and concentrate metals in both roots and shoots. Some plant species endemic to metalliferous soils accumulate metals in percent concentrations in the leaf dry matter.
Fly ash (FA)—a coal combustion residue of thermal power plants has been regarded as a problematic solid waste all over the world. The conventional disposal methods for FA lead to degradation and contamination of the arable land. However, several studies proposed that FA can be used as a soil-additive that may improve physical, chemical and biological properties of the degraded soils and is a source of readily available plant micro- and macro-nutrients. Numerous studies revealed that the lower FA incorporation in soil modifies the physico-chemical, biological and nutritional quality of the soil. However, the higher dosage of FA incorporation results in heavy metal pollution and hinders the microbial activity. Practical value of FA in agriculture as an “eco-friendly and economic” fertilizer or soil amendments can be established after repeated field experiments for each type of soil to confirm its quality and safety. Integrated Organic/Biotechnological approaches should be applied for the reducing toxicity of FA contaminated site near thermal power plants. Overall, study reveals that FA could be effectively used in the barren or sterile soil for improving quality and enhancing fertility. The purpose of this paper is to explore the possibility of FA addition into degraded soils for improving nutritional and physico-chemical properties.
This study investigates As accumulation and tolerance of the aquatic fern Azolla. Fifty strains of Azolla showed a large variation in As accumulation. The highest- and lowest-accumulating ferns among the 50 strains were chosen for further investigations. Azolla caroliniana accumulated two times more As than Azolla filiculoides owing to a higher influx velocity for arsenate. A. filiculoides was more resistant to external arsenate due to a lower uptake. Both strains showed a similar degree of tolerance to internal As. Arsenate and arsenite were the dominant As species in both Azolla strains, with methlyated As species accounting for <5% of the total As. A. filiculoides had a higher proportion of arsenite than A. caroliniana. Both strains effluxed more arsenate than arsenite, and the amount of As efflux was proportional to the amount of As accumulation. The potential of growing Azolla in paddy fields to reduce As transfer from soil and water to rice should be further evaluated.
Coal-based power generation is a principal source of electricity in India and many other countries. About 15-30% of the total amount of residue generated during coal combustion is fly ash (FA). FA is generally alkaline in nature and contains many toxic metals like Cr, Pb, Hg, As and Cd along with many essential elements like S, B, Ca, Na, Fe, Zn, Mn and P. Dumped FA contaminates the biosphere by mobilization of its fine particles and hazardous metals. Despite the negative environmental impact of FA, coal continues to be a major source of power production in India and therefore FA disposal is a major environmental issue. To overcome this problem, FA dumping sites have been started as a potential resource for biomass production of tree species. Phytoremediation is a strategy that uses plants to degrade, stabilize, and remove contaminants from soils, water and waste FA. Phytomanagement of FA is based on the plants' root systems, high biomass, woody nature, native nature, and resistance to pH, salinity, and toxic metals. Recently Indian researchers mostly from the National Botanical Research Institute have been working on phytoremediation and revegetation of FA dykes, inoculation of bacterial strains for reducing FA stress and biomass production from FA dykes. Many international researchers have worked on reclamation, revegetation and utilization of FA. FA utilization saves resources, mainly land (topsoil), water, coal, limestone and chemical fertilizer. Safe utilization of FA is a major concern around the world and regulatory bodies are enforcing stringent rules for the proper management of FA. This article summarizes various viable avenues in India for FA utilization and environmental management.
Fly ash is a by-product of coal-fired electricity generation plants. The prevalent practice of disposal is as slurry of ash and water to storage or ash ponds located near power stations. This has lain to waste thousands of hectares of land all over the world. Since leaching is often the cause of off-site contamination and pathway of introduction into the human environment, a study on the genotoxic effects of fly ash leachate is essential. Leachate prepared from the fly ash sample was analyzed for metal content, and tested for mutagenicity and genotoxicity. Analyses of metals show predominance of the metals-sodium, silicon, potassium, calcium, magnesium, iron, manganese, zinc, and sulphate. The Ames Salmonella mutagenicity assay, a short-term bacterial reverse mutation assay, was conducted on two-tester strains of Salmonella typhimurium strains TA97a and TA102. For genotoxicity, the alkaline version of comet assay on fly ash leachate was carried in vitro on human blood cells and in vivo on Nicotiana plants. The leachate was directly mutagenic and induced significant (P<0.05) concentration-dependent increases in DNA damage in whole blood cells, lymphocytes, and in Nicotiana plants. The comet parameters show increases in tail DNA percentage (%), tail length (mum), and olive tail moment (arbitrary units). Our results indicate that leachate from fly ash dumpsites has the genotoxic potential and may lead to adverse effects on vegetation and on the health of exposed human populations.
The aim of this paper was to investigate the capacity of a small water fern, Azolla caroliniana Willd. (Azollaceae), to purify waters polluted by Hg and Cr. Many plants are capable of accumulating heavy metals (called hyperaccumulators) and one of them is the water fern A. caroliniana. During 12 days of the experiment the fern was grown on the nutrient solution containing Hg2+, Cr3+ and CrO4(2-) ions, each in a concentration 0.1, 0.5 and 1.0 mg dm(-3). The presence of these ions caused a 20-31% inhibition of A. caroliniana growth, the highest in the presence of Hg(II) ions, in comparison to the control. After day 12 of the experiment, metal contents the solution decreased to 0-0.25 mg dm(-3), and this decrease comprised between 74 (Cr3+ 1.0 mg dm(-3) treatment) and 100% (CrO4(2-) 0.1 mg dm(-3) treatment). The fern took a lesser quantity of the metals from 0.1 mg dm(-3) treatments compared to 0.5 and 1.0 mg dm(-3) treatments. In the A. caroliniana tissues the concentration of heavy metals under investigation ranged from 71 to 964 mg kg(-1) dm; the highest level being found for Cr(III) containing nutrient solution.
In this study, we characterized lead (Pb2+) accumulation and storage by the aquatic fern Azolla filiculoides. Lead precipitates were detected in the vacuoles of mesophyll cells of Azolla plants cultured for 6 d in rich growth medium containing 20 mg l(-1) Pb2+. Energy dispersive spectroscopy (EDS) analysis of the relative element content of leaves collected from these plants revealed a 100% increase in the levels of P, S, Na and Ca and a 40% decrease in Mg and Cl compared to the untreated plants. Both Azolla whole plants and isolated apoplasts were incubated for 6 d in 20 mg l(-1) Pb2+. Lead content in the whole plant composed 0.37%, 2.3% and 1.8% of the dry weight after 2, 4 and 6 d of growth, respectively, while the isolated Azolla apoplast contained 0.125%, 1.22% and 1.4% Pb2+, respectively. Lead content in Azolla whole plant increase by 200%, 100% and 22% after 2, 4 and 6 d of growth, respectively, when compared to Azolla apoplast. Dark, electron dense deposits of lead were observed in light and transmission electron microscope in leaf cells treated with lead. All the observed lead deposits were localized in vacuoles while larger lead deposits were found in mature leaves than in young leaves. No lead deposits were found in cells of the cyanobiont Anabaena when the plants were exposed to similar conditions. Activity and content of V-H+-ATPase were studied in Azolla plants grown in the presence of 20, 40 and 80 mg l(-1) of lead for a period of 4 d. Activity of V-H+-ATPase was increased by 190%, 210% and 220%, respectively, but the content of V-H+-ATPase was reduced by all lead concentrations.
Arsenic-contaminated soil is one of the major arsenic sources for drinking water. Phytoremediation, an emerging, plant-based technology for the removal of toxic contaminants from soil and water, has been receiving renewed attention. Although a number of plants have been identified as hyperaccumulators for the phytoextraction of a variety of metals, and some have been used in field applications, no hyperaccumulator for arsenic had been previously reported until the recent discovery of Brake fern (Pteris vittata), which can hyperaccumulate arsenic from soils. This finding may open a door for phytoremediation of arsenic-contaminated soils. Speciation and distribution of arsenic in the plant can provide important information helpful to understanding the mechanisms for arsenic accumulation, translocation, and transformation. In this study, plant samples after 20 weeks of growth in an arsenic-contaminated soil were used for arsenic speciation and distribution study. A mixture of methanol/water (1:1) was used to extract arsenic compounds from the plant tissue. Recoveries of 85 to 100% were obtained for most parts of the plant (rhizomes, fiddle heads, young fronds and old fronds) except for roots, for which extraction efficiency was approximately 60%. The results of this study demonstrate the ability of Brake fern as an arsenic hyperaccumulator. It transfers arsenic rapidly from soil to aboveground biomass with only minimal arsenic concentration in the roots. The arsenic is found to be predominantly as inorganic species; and it was hypothesized that the plant uptakes arsenic as arsenate [As(V)I and arsenate was converted to arsenite [As(III)] within the plant. The mechanisms of arsenic uptake, translocation, and transformation by this plant are not known and are the objectives of our on-going research.
A field study was conducted in the fly ash lagoons of Santandih Thermal Power Plant located in West Bengal (India) to find out total, EDTA and DTPA extractable metals in fly ash and their bioaccumulation in root and shoot portion of the naturally growing vegetation. Fly ash sample has alkaline pH and low conductivity. The concentration of total Cu, Zn, Pb and Ni were found higher than weathered fly ash and natural soil, where as Co, Cd and Cr were found traces. Five dominant vegetation namely, Typha latifolia, Fimbristylis dichotoma, Amaranthus defluxes, Saccharum spontaenum and Cynodon dactylon were collected in the winter months (November-December). Bioaccumulation of metals in root and shoot portions were found varied significantly among the species, but all concentration were found within toxic limits. Correlation between total, DTPA and EDTA extractable metals viz. root and shoot metals concentration were studied. Translocation factor (TF) for Cu, Zn and Ni were found less than unity, indicates that these metals are immobilized in the root part of the plants. Metals like Mn have TF greater than unity. The study infers that natural vegetation removed Mn by phytoextraction mechanisms (TF > 1), while other metals like Zn, Cu, Pb and Ni were removed by rhizofiltration mechanisms (TF < 1). The field study revealed that T. latifolia and S. spontaenum plants could be used for bioremediation of fly ash lagoon.
Crop and food chain effects of toxic elements in sludges and effluents
- R L Chaney
Chaney, R.L., 1973. Crop and food chain effects of toxic elements in sludges and
effluents. In: Proceedings of the Joint Conference on Recycling Municipal
Sludge and Effluents on Land. National Association of State Universities and
Land-Grant Colleges, Washington, DC, pp. 129-141.
Principles of Plant Nutrition The Netherlands The Indian perspective of utilizing fly ash in phytoremediation, phytomanagement and biomass production
- K Mengel
- E A Kirkby
Mengel, K., Kirkby, E.A., 2001. Principles of Plant Nutrition, fifth ed. Kluwer Academic Publishers, Dordrecht, The Netherlands, p. 849. Pandey, V.C., Abhilash, P.C., Singh, N., 2009. The Indian perspective of utilizing fly ash in phytoremediation, phytomanagement and biomass production. J. Environ. Manage. 90, 2943–2958.
Human and Ecological Risk Assessment of Coal Combustion Wastes (draft)
- Us Epa
US EPA, 2007. Human and Ecological Risk Assessment of Coal Combustion Wastes
(draft).
A comparison of heavy metals in lichen (Pyxine subcinerea), mango bark and soil
- V Shukla
- D K Patel
- D K Upreti
- M Yunus
- S Prasad
Shukla, V., Patel, D.K., Upreti, D.K., Yunus, M., Prasad, S., 2012. A comparison of
heavy metals in lichen (Pyxine subcinerea), mango bark and soil. Int. J. Environ.
Sci. Technol. http://dx.doi.org/10.1007/s13762-012-0075-1.