Phytoextraction Of Cadmium Research Articles

Management of Singapore Daisy (an Invasive Weed) through Utilisation

Singapore daisy is a perennial invasive weed of Kerala having the potential to adversely affect the environment and biodiversity. One of the possible methods for the management of invasive weeds is through their utilisation. The study explored the potential of Singapore daisy for phytoremediation of contaminated soils along with its potential as a fodder crop. The results revealed that the invasive plant has the potential for phytoextraction (BAC and TF >1) of cadmium and lead; phytostabilisation (BCF>1; TF<1) of cadmium, arsenic, chromium and lead. Analysis of proximate principles of Singapore daisy revealed that the nutritive value was comparable to that of common fodder crops (also, K/Ca+Mg ratio was 1.19) cultivated in Kerala. However, since the plant has phytoremediation potential, it cannot be recommended as a fodder crop unless it is growing in uncontaminated soil.

Bio-pump cadmium phytoextraction efficiency promoted by phytohormones in Festuca arundinacea

The leaves of Festuca arundinacea can excrete cadmium (Cd) out onto the leaf surface, leading to a bio-pump phytoremediation strategy based on “root uptake—root-to-leaf translocation—leaf excretion”. However, the bio-bump efficiency of soil Cd is a limiting factor for the implementation of this novel technology. Bio-bump remediation involves the bioprocess of plant root uptake from soil, root-to-leaf translocation, and leaf hydathode excretion. Here we show the significant effects of phytohormones in regulating the bio-pump phytoextraction efficiency. The results showed that salicylic acid and ethylene enhanced the whole process of Cd root uptake, root-to-leaf translocation, and leaf excretion, promoting the bio-pump phytoextraction efficiency by 63.6% and 73.8%, respectively. Gibberellin also greatly promoted Cd translocation, leaf excretion, and phytoextraction, but did not significantly impact Cd root uptake. Our results indicate that salicylic acid and ethylene could be recommended to promote bio-pump phytoextraction efficiency in F. arundinacea. Gibberellin might be used for a short-term promotion of the leaf Cd excretion.

Evaluation of cadmium phytoextraction potential of peanut and the rhizospheric properties of specific cultivars

Phytoextraction is an effective technique for removing cadmium (Cd) from contaminated farmland, thus achieving real ecological restoration. To clarify the potential of peanut phytoextraction, we designed a pot experiment to assess the Cd accumulation in peanut. In addition, the contribution of rhizosphere microorganisms in Cd accumulation was explored. The results demonstrate that the Cd content in peanut tissue ranked as follows: stem > leaf > root > needle > husk > kernel, with Cd mainly accumulated in the stems (41.92%) and leaves (40.27%). The bioconcentration factor for all cultivars was greater than 1, in agreement with the concept of phytoextraction. Cd extraction from peanut plants grown per season was appreciable, estimated as being from 28.5 g Cd ha−1 to 121.5 g Cd ha−1. Subsequently, based on the Cd accumulation characteristics, cultivars BS1016 and HY20 were identified as the high Cd-accumulating cultivars (HACs), and LH11 and LH14 were identified as the low Cd-accumulating cultivars (LACs), for further study as specific cultivars. For Cd-contaminated soil, high accumulation in HACs was associated with increased Cd bioavailability. The peanut rhizosphere attracted different microorganisms to cope with Cd stress. Compared with LACs, the rhizosphere of HACs tended to be enriched with high Cd-resistant microorganisms, which directly or indirectly participate in Cd activation (for example, Acidimicrobiia class of bacteria, Rhizophlyctis genus of fungi). Correlation analysis confirmed that Rhizophlyctis was a good choice to enhance the potential for Cd phytoextraction using peanut. This study demonstrates the advantages and rhizosphere mechanisms of using peanut for bioremediating Cd-contaminated soil, providing a new approach for remediation and targeted regulation of Cd-contaminated farmland.

Single and combined phytoextraction of lead and cadmium on submerged plants Potamogeton pusillus L.: removal, bioaccumulation pattern, and phytotoxicity.

Under the present investigation, the submerged plant Potamogeton pusillus has been tested for the removal of lead (Pb) and cadmium (Cd). P. pusillus removal efficiency and accumulation capacity were examined in separated Pb and Cd solutions, at 0.5, 1.0, and 2mg L-1, and in solutions where both metals were present at the same concentration (0.5, 1.0, and 2mg L-1), under laboratory conditions for 3, 7, and 10days. Also, we examined the removal efficiency and accumulation capacity when a set of plants were exposed to 0.5mg L-1 of Pb (or Cd) and increasing concentrations (0.5, 1, and 2mg L-1) of Cd (or Pb) for 10days. The effect of Cd and Pb was assessed by measuring changes in the chlorophylls, carotenoids, and malondialdehyde contents. Results showed that P. pusillus could accumulate Cd and Pb from individual solutions. Roots and leaves accumulated the highest amount of Cd and Pb followed by the stems. Some phytotoxic effects were observed, especially at individual Cd exposures, but these effects were not observed in the two-metal system. The removal and accumulation of Pb by P. pusillus were significantly enhanced in the presence of Cd under certain conditions, presenting a good alternative for the removal of these metals from polluted aquifers. To the extent of our knowledge, this is the first report on both enhanced phytoextraction of Pb in the presence of Cd and bioaccumulation of these heavy metals by P. pusillus.

Expression of Concern: Effect of farmyard manure, elemental sulphur and EDTA on growth and phytoextraction of cadmium by spider plants (Chlorophytum comosum L.) under Cd stress (Chemosphere, Volume 313, February 2023, 137385)

Expression of Concern: Effect of farmyard manure, elemental sulphur and EDTA on growth and phytoextraction of cadmium by spider plants (Chlorophytum comosum L.) under Cd stress (Chemosphere, Volume 313, February 2023, 137385)

Evaluating capability of two halophyte plants for phytoextraction of cadmium from contaminated soils

Selecting an appropriate plant is a key factor for the phytoextraction of heavy metals from contaminated soils. The possibility of using two halophytes for the remediation of cadmium (Cd) from contaminated soils was investigated. Consequently, an experiment with Chenopodium album L. and Chenopodium botrys L. including Cd treatments of 0, 5,10, 20, 40, 60, 80 and 100 ppm was conducted. Designated analyses including fresh weight, dry weight, and Cd concentrations in shoots and roots were performed. Results indicated that for both plants, a logarithmic model performed best to demonstrate the relationship between total soil Cd with shoot Cd and dry matter. Although both halophytes had considerable capability to remediate Cd from soils, C. botrys demonstrated greater potential to accumulate Cd in shoots. The range of bioconcentration factor (BCF) in C. botrys was obtained to be 0.8 to 8.8 and in C. album was 0.4 to 1.73. For C album, BCF in most treatments was lower than 1.0, but for C. botrys, it was mostly larger than 1.0. Although both plants can be used as hyperaccumulators to remediate Cd-polluted soils, the clean-up time of C. album under higher Cd concentrations was shorter than C. botrys L.

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How exogenous ligand enhances the efficiency of cadmium phytoextraction from soils?

Many experiments showed that exogenous ligands could enhance cadmium (Cd) phytoextraction efficiency in soils. Previous studies suggested that the dissociation and the apoplastic uptake of Cd complex could not fully explain the increase of root Cd uptake. Two hypotheses are evaluated to explain enhanced Cd uptake in the presence of ligand: i) enhanced apoplastic uptake of complex due to reduced apoplastic resistance and ii) complex internalization by membrane transporters. Resultsshow that the ligand affinity for Cd is a key characteristic determining the potential mechanism for enhanced Cd uptake. When low molecular weight organic acids are applied, the complex dissociation could generally be fast (> 10−3.3 s−1) and result in the increased Cd uptake. When hydrophilic aminopolycarboxylic acids (APCAs) are applied in experiments without water or temperature stresses to the plant, the root water uptake flux could very likely be high (> 10−7.8 dm s−1), and the strong apoplastic complex uptake could enhance the root Cd uptake. When lipophilic APCAs are applied, the strong internalization of the complex by membrane transporters could result in the increased Cd uptake if the maximum internalization rate is high (> 10−12 mol dm−2 s−1). However, the complex internalization by membrane transporters must be experimentally confirmed.

Analysis of double phytoextraction of Cadmium and microplastics by Galinsoga Quadriradiata in soil An exploration for a comprehensive treatment method for the environment

The wide usage of microplastics and heavy metals has led to the accumulation of these pollutants in our environment. Among heavy metals and microplastics, Cadmium (Cd), polyvinyl chloride (PVC), and polyethylene (PE) are the most severe and ubiquitous pollutants. With large surface areas, microplastics have the ability to absorb metal ions, potentially performing "carrier effect", by which microparticles enhance the transfer of other pollutants from soil to plants. Phytoextraction has been shown to be the most effective strategy to remediate heavy metal contamination. In this study, we selected Galinsoga quadriradiata (G. quadriradiata) as the test species to investigate the effectiveness of phytoextraction in soil contaminated with Cd, PVC and PE. According to our results, G. quadriradiata present effective phytoextraction to Cd and microplastics. However, the carrier effect between Cd and PVC or PE only exists in the value of maximal quantum efficiency of photosystem II (Fv/Fm) but has no effect on the uptake of Cd by G. quadriradiata. For future studies, we propose to investigate the carrier effect between heavy metals and microplastics in plants, test the pathway of microplastics by which they are up-taken by plants from soil, and increase the efficiency of phytoextraction by exposing plants (such as G. quadriradiata) that have been proved to absorb heavy metal to microplastics.

Correction: Effects of Ascophyllum nodosum-based Biostimulants on Improving Phytoextraction of Cadmium and Lead in Contaminated Soils

Correction: Effects of Ascophyllum nodosum-based Biostimulants on Improving Phytoextraction of Cadmium and Lead in Contaminated Soils

Cadmium up Taking and Allocation in Wood Species Associated to Cacao Agroforestry Systems and Its Potential Role for Phytoextraction.

Trees in cacao Agroforestry systems (AFS) may present a high potential for cadmium (Cd) phytoextraction, helping to reduce Cd in cacao (Theobroma cacao L.) plants grown in contaminated soils. To assess this potential, four forest fine-woody species commonly found in cacao high-productive sites in Colombia (Tabebuia rosea, Terminalia superba, Albizia guachapele, and Cariniana pyriformis) were exposed to contrasting CdCl2 contamination levels (0, 6, and 12 ppm) on a hydroponic medium. Growth dynamics, tolerance index (TI), and Cd concentration and allocation in leaves, stems, and roots were evaluated for up to 90 days after initial exposure. T. superba, A. guachapele, and C. pyriformis were classified as moderately tolerant (TI > 0.6), and T. rosea was considered a sensitive species (TI < 0.35) under 12 ppm Cd contamination. Despite showing a high stem Cd concentration, C. pyriformis also showed the lowest relative growth rate. Among the evaluated forest species, A. guachapele exhibited the highest Cd accumulation capacity per plant (2.02 mg plant-1) but also exhibited a higher Cd allocation to leaves (4%) and a strong decrease in leaf and stem dry mass after 90 days of exposure (~75% and 50% respectively, compared to control treatments). Taking together all the favorable features exhibited by T. superba as compared to other CAFS tree species and recognized phytoextractor tree species in the literature, such as Cd hyperaccumulation, high tolerance index, low Cd concentration in leaves, and high Cd allocation to the stem (harvestable as wood), this species is considered to have a high potential for cadmium phytoextraction in cocoa agroforestry systems.

Exogenous plant growth regulator and foliar fertilizers for phytoextraction of cadmium with Boehmeria nivea [L.] Gaudich from contaminated field soil

As a enrichment plant, ramie can be used for the phytoremediation of cadmium (Cd)-contaminated soil. However, it is worth exploring the role of plant growth regulators and foliar fertilizers in the process of plant growth and development and Cd adsorption. By measuring the agronomic traits, Cd content of aboveground and underground ramie, calculating the Cd transfer coefficient (TF) and Cd bioconcentration factors (BCF), and the correlation between various indicators. This study examined the effects of plant growth regulators and foliar fertilizers on ramie’s capacity for Cd accumulation and transportation. Plant growth regulators and foliar fertilizers increased the Cd content of the aboveground ramie, reduced the Cd content of the underground ramie, and increased the TF. Among them, GA-1 increased the Cd content of the aboveground ramie to 3 times more than that of the control and reduced the Cd content of the underground ramie by 54.76%. Salicylic acid (SA) increased the Cd content of the aboveground ramie to three times more than that of the control. The combination of GA and foliar fertilizer reduced the Cd content of the aboveground and underground ramie and the TF and BCF of the underground ramie. After the hormones were sprayed, the TF of ramie had a significant positive correlation with the Cd content of the aboveground ramie; the BCF of the aboveground ramie had a significant positive correlation with the Cd content and TF of the aboveground ramie. The results indicate that Brassinolide (BR), gibberellin (GA), ethephon (ETH), polyamines (PAs), and salicylic acid (SA) have different effects on the enrichment and transport of Cd in ramie. This study provided an effective method to improve the capacity for ramie to adsorb heavy metals during cultivation.

Enhanced cadmium phytoextraction efficiency of ryegrass (Lolium perenne L.) by porous media immobilized Enterobacter sp. TY-1

Although studies on immobilized microorganisms have been conducted, their performance remains unclear for enhancing plants to remediate cadmium (Cd)-contaminated soil. In this study, a Cd-resistant strain TY-1 with good plant growth promotion traits was immobilized by biochar (BC) or oyster shell (OS) power to strengthen ryegrass to remediate Cd-contaminated soil. SEM-EDS combined with FTIR showed that TY-1 could tolerate Cd toxicity by surface precipitation, and functional groups such as hydroxyl and carbonyl groups might be involved. In the biocomposite treatments, soil pH increased, and the activity of fertility-related enzymes such as dehydrogenase increased by 109.01%–128.01%. The relative abundance of genus Saccharimonadales decreased from 7.97% to 3.35% in BS-TY and 2.61% in OS-TY, respectively. Thus, a suitable environment for ryegrass growth was created. The fresh weight, dry weight, plant height and Cd accumulation of ryegrass in TY treatment increased by 122.92%, 114.81%, 42.08% and 8.05%, respectively, compared to the control. Cd concentration in ryegrass was further increased in BC-TY and OS-TY by 24.14% and 40.23%, respectively. The improvement in soil microcosm and plant biomass forms an ongoing virtuous cycle, demonstrating that using carrier materials to improve the efficiency of microbial-assisted phytoremediation is realistic and feasible.

Phytoremediation method and Brassica family: Removal of chromium, cadmium and lead accumulation with broccoli (Brassica oleracea var. italica)

Phytoremediation is the most cost effective and applicable technique to clean contaminated soils. The study was carried out in controlled conditions. Cadmium was applied as only cadmium (30 mgkg−1), and together with a chelator as Cd (30 mgkg−1) + EDTA, in triplicates. Chromium was applied as only chromium (10 mg/kg−1), and together with a chelator as Cr (10 mgkg−1) + EDTA. Similarly, lead was applied as only lead (100 mgkg−1), and together with a chelator as Pb (100 mgkg−1) + EDTA. The highest root and shoot dry weights were detected in lead and chromium applied pots. The highest lead, cadmium and chromium concentrations in the shoot of broccoli (Brassica oleracea var.italica) were found to be 14.0 mgkg−1, 6.67 mg kg-1and, 5.17 mg kg−1, respectively, in the chelated applications. The order of accumulation in the root was Cr > Pb > Cd. Broccoli was shown to be effective in phytoextraction of Pb Chromium was especially accumulated in the roots of broccoli which indicated that this plant was successful for phytostabilization of Cr. Broccoli can be employed for both phytostabilization and phytoextraction of cadmium. The results revealed that broccoli played a role in the remediation of lead, chromium and cadmium heavy metals as a hyper accumulator plant.

Phytoextraction and Migration Patterns of Cadmium in Contaminated Soils by Pennisetum hybridum.

This study was conducted to identify soil cadmium (Cd) removal pathways and their contribution rates during phytoremediation by Pennisetum hybridum, as well as to comprehensively assess its phytoremediation potential. Multilayered soil column tests and farmland-simulating lysimeter tests were conducted to investigate the Cd phytoextraction and migration patterns in topsoil and subsoil simultaneously. The aboveground annual yield of P. hybridum grown in the lysimeter was 206 ton·ha-1. The total amount of Cd extracted in P. hybridum shoots was 234 g·ha-1, which was similar to that of other typical Cd-hyperaccumulating plants such as Sedum alfredii. After the test, the topsoil Cd removal rate was 21.50-35.81%, whereas the extraction efficiency in P. hybridum shoots was only 4.17-8.53%. These findings indicate that extraction by plant shoots is not the most important contributor to the decrease of Cd in the topsoil. The proportion of Cd retained by the root cell wall was approximately 50% of the total Cd in the root. Based on column test results, P. hybridum treatment led to a significant decrease in soil pH and considerably enhanced Cd migration to subsoil and groundwater. P. hybridum decreases Cd in the topsoil through multiple pathways and provides a relatively ideal material for phytoremediation of Cd-contaminated acid soils.

Pleiotropic melatonin-mediated responses on growth and cadmium phytoextraction of Brassica napus: A bioecological trial for enhancing phytoremediation of soil cadmium

Melatonin (MT) has recently gained significant scientific interest, though its mechanism of action in enhancing plant vigor, cadmium (Cd) tolerance, and Cd phytoremediation processes are poorly understood. Therefore, here we investigated the beneficial role of MT in improving growth and Cd remediation potential of rapeseed (Brassica napus). Plants, with or without MT (200 µM L−1), were subjected to Cd stress (30 mg kg1). Without MT, higher Cd accumulation (up to 99%) negatively affected plant growth and developmental feature as well as altered expression of several key genes (DEGs) involved in different molecular pathways of B. napus. As compared to only Cd-stressed counterparts, MT-treated plants exhibited better physiological performance as indicated by improved leaf photosynthetic and gaseous exchange processes (3–48%) followed by plant growth (up to 50%), fresh plant biomass (up to 45%), dry plant biomass (up to 32%), and growth tolerance indices (up to 50%) under Cd exposure. MT application enhanced Cd tolerance and phytoremediation capacity of B. napus by augmenting (1) Cd accumulation in plant tissues and its translocation to above-ground parts (by up to 45.0%), (2) Cd distribution in the leaf cell wall (by up to 42%), and (3) Cd detoxification by elevating phytochelatins (by up to 8%) and metallothioneins (by upto 14%) biosynthesis, in comparison to Cd-treated plants. MT played a protective role in stabilizing hydrogen peroxide and malondialdehyde levels in the tissue of the Cd-treated plants by enhancing the content of osmolytes (proline and total soluble protein) and activities of antioxidant enzymes (SOD, CAT, APX and GR). Transcriptomic analysis revealed that MT regulated 1809 differentially expressed genes (828 up and 981 down) together with 297 commonly expressed DEGs (CK vs Cd and Cd vs CdMT groups) involved in plant-pathogen interaction pathway, protein processing in the endoplasmic reticulum pathway, mitogen-activated protein kinase signaling pathway, and plant hormone signal transduction pathway which ultimately promoted plant growth and Cd remediation potential in the Cd-stressed plants. These results provide insights into the unexplored pleiotropic beneficial action of MT in enhancing in the growth and Cd phytoextraction potential of B. napus, paving the way for developing Cd-tolerant oilseed crops with higher remediation capacity as a bioecological trial for enhancing phytoremediation of hazardous toxic metals in the environment.

Effect of plant growth–promoting rhizobacteria on oilseed rape Brassica juncea and phytoextraction of cadmium

Effect of plant growth–promoting rhizobacteria on oilseed rape Brassica juncea and phytoextraction of cadmium

Assessment of natural low molecular weight organic acids in facilitating cadmium phytoextraction by Lepidium didymus (Brassicaceae).

The present study examined the ability of three naturally occurring low molecular weight organic acids (tartaric, TA; citric, CA; and oxalic, OA) to improve the efficiency of cadmium (Cd) phytoextraction in Lepidium didymus L. (Brassicaceae). The plants were grown in soil containing three different concentrations, i.e., 35, 105, and 175mgkg-1, of total Cd and 10mM of TA, CA, and OA. After 6weeks, plant height, dry biomass, photosynthetic traits, and metal accumulation were determined. All three organic chelants significantly increased the Cd accumulation in L. didymus plants; however, the greatest accumulation was seen with TA (TA > OA > CA). In general, Cd accumulation was the highest in the roots, followed by the stems, and the leaves. Highest BCFStem was observed upon the addition of TA (7.02) and CA (5.90) at Cd35, compared to Cd-alone (3.52) treatment. The BCF was the highest in the stem (7.02) and leaves (3.97) under Cd35 treatment supplemented with TA. The BCFRoot in the plants under different chelant treatments were in the following order: Cd35 + TA (~ 100) > Cd35 + OA (~ 84) > Cd35 + TA (~ 83). The stress tolerance index and translocation factor (root-stem) were maximal at Cd175 with TA and OA supplementation, respectively. The study concludes that L. didymus could be a viable option for Cd-remediation projects, and the addition of TA improved its phytoextraction efficiency.

Effects of Ascophyllum nodosum-based Biostimulants on Improving Phytoextraction of Cadmium and Lead in Contaminated Soils

Effects of Ascophyllum nodosum-based Biostimulants on Improving Phytoextraction of Cadmium and Lead in Contaminated Soils

Nitrogen level induces sex-specific cadmium phloem remobilization and cell wall segregation in Populus cathayana

Nitrogen (N) fertilization can improve the phytoremediation of contaminated soils. However, limited information is available on the effects and mechanisms of N availability on Cadmium (Cd) phytoextraction by dioecious plants. This study employed female and male Populus cathayana to examine sex-specific long-distance transport and cell wall Cd sequestration. Females had a greater ability to transport Cd from roots to shoots and accumulated more Cd in leaves, but had less Cd bound to the cell wall and S-containing ligands than males, irrespective of N availability. N availability affected the sex-specific ability to transport Cd and chelate it within cell walls and with S-containing ligands. Low N promoted phloem-mediated upward and downward Cd transport and total Cd accumulation in both sexes, and such effects on phloem-mediated downward Cd transport were greater than those on upward Cd transport in males. However, low-N concentration-induced Cd phloem transport was more significant in females than males. In females, low N reduced Cd accumulation in leaves via increased phloem-mediated Cd downward transport, and this Cd was subsequently sequestered in the bark and root cell walls. In contrast, for males, high N promoted xylem-mediated Cd transport to shoots and Cd sequestration in the bark but reduced phloem-mediated Cd downward transport and subsequent sequestration in root cell walls. Sex-specific genes related to root Cd transport and translocation from roots to shoots were also affected by N supply in roots. These results suggested that N availability reduced the sex-based difference in total Cd accumulation, translocation and Cd detoxification, and males showed stronger Cd tolerance than females at both N availabilities.