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Graphene oxide (GO, a popular 2D graphene-based nanomaterial) has developed quickly and has received considerable attention for its applications in environmental protection and pollutant removal. However, significant knowledge gaps still exist about the interaction characteristic and joint toxicity mechanism of GO and cadmium (Cd) on aquatic organisms. In this study, GO showed a high adsorption capacity (120. 6 mg/g) and strong adsorption affinity (K

Considering the stability and economy of immobilized enzymes, this study prepared co-modified biochar immobilized laccase product named Fe

Two-dimensional transition metal dichalcogenide (TMDC) nanomaterials have attracted tremendous research interest in various fields, but the effects of eco-corona formation on the transformation mechanisms and ecological risk of TMDCs remain largely unknown. The effect of eco-corona formation on TMDC reactivity was explored using extracellular polymeric substances (EPS) as the eco-corona constituents and single-layer molybdenum disulfide (SLMoS

Over the past few decades, data-driven machine learning (ML) has distinguished itself from hypothesis-driven studies and has recently received much attention in environmental toxicology. However, the use of ML in environmental toxicology remains in the early stages, with knowledge gaps, technical bottlenecks in data quality, high-dimensional/heterogeneous/small-sample data analysis and model interpretability, and a lack of an in-depth understanding of environmental toxicology. Given the above problems, we review the recent progress in the literature and highlight state-of-the-art toxicological studies using ML (such as learning and predicting toxicity in complicated biosystems and multiple-factor environmental scenarios of long-term and large-scale pollution). Beyond predicting simple biological endpoints by integrating untargeted omics and adverse outcome pathways, ML development should focus on revealing toxicological mechanisms. The integration of data-driven ML with other methods (e.g., omics analysis and adverse outcome pathway frameworks) endows ML with widely promising application in revealing toxicological mechanisms. High-quality databases and interpretable algorithms are urgently needed for toxicology and environmental science. Addressing the core issues and future challenges for ML in this review may narrow the knowledge gap between environmental toxicity and computational science and facilitate the control of environmental risk in the future.

The transformation of silver ions (Ag

Azo dye pollution has become a worldwide issue, and the current treatment methods can hardly meet the expected emission standards. Microbial electrochemical systems (MESs) show promising applications for decolorization, but their performance critically depends on the microorganisms. Electrode modification is an interesting method of improving decolorization performance. However, the mechanisms of how the modification can affect microbial communities and the decolorization process remain unclear. Here, a modified anode with polyaniline (PANI) and graphene was fabricated via electro-deposition. Consequently, the highest decolorization efficiency was obtained. The Congo red (CR) decolorization rate of the MESs with the PANI/graphene-modified electrode (PG) reached 90% at 54 h. By contrast, the CR decolorization rates of the MESs with the PANI-modified electrode (P) and those of the MESs with the unmodified electrode (C) only reached 68% and 79%, respectively. Results of the microbial community analysis showed abundant Methanobrevibacter arboriphilus in PG (11%), which was 5.5 times that in C (2%) at 18 h. This phenomenon may be related to the rapid decolorization. The upregulated metabolism pathways, including arginine and proline metabolism, purine metabolism, arginine biosynthesis, and riboflavin metabolism, provided more electron shuttles and redox mediators that facilitated the extracellular electron transfer. Therefore, the PG-modified electrode facilitated the decolorization by altering certain metabolic pathways. This study can help to improve the guideline on the potential application of MESs for wastewater treatment.

At present, the uptake and accumulation of nanoplastics by plants have raised particular concerns. However, molecular mechanisms underlying nanoplastic phytotoxicity are still vague and insufficient. To address this scientific gap, we analyzed the transcriptome response of hydroponically grown wheat (Triticum aestivum L.) to polystyrene nanoplastics (PSNPs) (100 nm) by integrating the differentially expressed gene analysis (DEGA) and the weighted gene correlation network analysis (WGCNA). PSNPs could significantly shape the gene expression patterns of wheat in a tissue-specific manner. Four candidate modules and corresponding hub genes associated with plant traits were identified using WGCNA. PSNPs significantly altered carbon metabolism, amino acid biosynthesis, mitogen-activated protein kinase (MAPK) signaling pathway-plant, plant hormone signal transduction, and plant-pathogen interaction Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. In addition, some Gene Ontology (GO) terms associated with the metal ion transport were further screened. These findings shed new light on the phytotoxic mechanism and environmental implication behind the interaction of nanoplastics and crop plants, and advance our understanding of the potential adverse effect induced by the presence of nanoplastics in agricultural systems.

Zeolitic imidazole frameworks (ZIFs) have attracted a considerable amount of attention for use in environmental applications (e.g., pollutant adsorption and photocatalysis in water treatments). The environmental stability and toxicity of ZIFs are key prerequisites for their practical applications, but information about these factors is largely lacking. The present work finds that pristine ZIFs (ZIF-8 and ZIF-67) photodegrade from frame structures into two-dimensional nanosheets and are oxidized to zinc carbonate (ZIF-8) and Co3O4 (ZIF-67) under visible-light irradiation. The photoinduced electrons, holes and free radicals promote dissolution of the metal cores and organic ligands, leading to collapse of the frame structure. The photodegradation of ZIF-8 alleviates developmental inhibition, oxidative stress, plasmolysis, and photosynthetic toxicity, while the photodegradation of ZIF-67 aggravates nanotoxicity. The integration of metabolomics and transcriptomics analysis reveals that unsaturated fatty acid biosynthesis and metal ion-binding transcription contribute to the altered toxicity of ZIF photodegradation. These findings highlight the roles of photodegradation in structural transformation and alteration of the toxicity of ZIFs, alarming the study of pristine metal-organic frameworks (MOFs).

Hydrolysis is generally considered as the main pathway for the degradation of ester-type pollutants in aquatic environments. In this study, we found that when methanol or ethanol presented as the external carbon in the activated sludge, transesterification is very important for the degradation of para-hydroxybenzoic acid esters (parabens). In the activated sludge solutions with 1% methanol added, contribution of transesterification to the degradation of the propyl substituted paraben (PrP) and ethyl substituted paraben (EtP) accounted for 46% and 83%, respectively, in the early stage of the reaction. This indicates that in aquatic environments with alcohols presence, parabens prefer to form small molecule homologues than hydrolysis to acid. The predominant transesterification in the activated sludge is related to enzyme preference. Amano lipase from Pseudomonas fluorescens was verified to catalyze hydrolysis and transesterification of parabens, while the latter was dominant in water solution with 1% methanol or ethanol. Considering the common application of small molecular alcohols as the external carbon sources in wastewater treatment plants, transesterification might be an important pathway for the degradation of parabens pollutants in these engineering aquatic environments.

Soil contaminated by aged petroleum hydrocarbons is faced with scarcity of electron acceptors, low activity of functional microbes and inefficient electron transfer, which hinder the bioremediation application. The soil microbial fuel cell (MFC) simultaneously solves these problems with bioelectricity production. In this study, five types of surfactants were introduced to enhance the bioavailability of aged petroleum hydrocarbon in soils. The ampholytic surfactant (lecithos) was optimal due to the highest bioelectricity generation (0.321C d −1 g −1 ) and promoted hydrocarbon degradation (328%), while the nonionic (glyceryl monostearate) and cationic (cetyltrimethylammonium bromide) surfactants were inefficient. The surfactants induced a special microbial enrichment affiliated with Proteobacteria , Firmicutes , Bacteroidetes , Actinobacteria , Chloroflexi , Planctomycetes and Acidobacteria (93%–99% of total) in soil MFCs. The anionic surfactant (sodium dodecyl sulfate) exhibited the strongest selectivity, and α- proteobacteria and γ - proteobacteria abundances decreased while Clostridia increased, much like the result obtained with the biosurfactant β -cyclodextrin. Furthermore, Bacillus abundance was increased in connected soil MFCs, except addition of lecithos in which Clostridium increased to 14.88% from 3.61% in the control. The high correlations among Bacillus , Phenylobacterium , Solibacillus (0.9162–0.9577) and among Alcaligenes , Dysgonomonas , Sedimentibacter (0.9538–0.9966) indicated a metabolic network of microorganisms in the soil bioelectrochemical remediation system.

Oil spills occur frequently worldwide, resulting in severe damage to water and to human health. Polycyclic aromatic hydrocarbons (PAHs) are the primary toxic components in oil contamination. PAH-degrading microbes have attracted significant attention, but difficulty in their selection and proliferation limits their applications. Graphene oxide quantum dots (GOQDs) improve the proliferation of an indigenous PAH-degrading strain, Bacillus cereus, more effectively than large graphene oxide flakes. Bacillus cereus can metabolize a variety of xenobiotic aromatic compounds as carbon sources and is used in bioremediation. GOQDs contain a variety of aromatic hydrocarbon structures, explaining why the bacteria achieve strong tolerance to PAHs. GOQD-activated cytokinesis increases the secretion of substances important for biofilm formation (extracellular polymeric substances), which further accelerates PAH removal. Proteomic analysis reveals the molecular mechanisms underlying GOQD-induced microbial proliferation. GOQDs induce the overexpression of microbial divisomal proteins associated with division initiation, DNA replication and peptidoglycan hydrolysis/synthesis. Importantly, PAH removal mediated by GOQD-treated Bacillus cereus does not require the addition of GOQDs. The effects of GOQDs on a strain persist for at least 20 generations, suggesting their possible use in low-cost applications. This work proposes a strategy to remove oil contamination using an indigenous bacterial system enhanced by nanomaterials.

With the wide use of graphene-like nanosheets, especially in agriculture, their release into the environment, it is crucial to grasp the fate of nanosheets in soil and minimum ecological risks. The present work discovered that leaching and migration of nanosheets (rGO) in soil is affected by soil porosity and adsorption processes. And the contents of rGO−Pd in soil layers and leachate increased and then decreased with the decreased of soil porosity. Moreover, physicochemical properties of rGO−Pd nanosheets changed by leaching processes, especially the changes of morphology, thickness and oxygen functional groups. Leaching of rGO−Pd also interfered the soil microbial homeostasis accompanied by the increase of microbial species richness and community diversity. In addition, rGO−Pd altered the usage of carbon sources by edaphon. The utilization of carbon sources by soil microbes, such as polymers, sugars, phenolic acids, carboxylic acids, amino acids, and amines, was also reduced by nanosheets. These findings provide new insights into environmental behaviors of nanomaterials and nanogeochemistry.

Sawdust and wheat straw biochars prepared at 300°C and 500°C were applied to petroleum-polluted soil for an 84-day incubation to estimate their effectiveness on polycyclic aromatic hydrocarbons (PAHs) removal. Biochars alone were most effective at reducing PAHs contents. However, adding biochar to soils in company with NaN3 solution resulted in a decreasing trend in terms of PAHs removal, which was even lower than treatment CK without biochar. Moreover, it was discovered by PCR-DGGE files and sequencing analysis that the predominant bacterial diversity slightly decreased but the abundance of some specific taxa, including PAHs degraders, was promoted with biochar input. These results highlighted the potential of biochar application on accelerating PAHs biodegradation, which could be attributed to the properties of biochars that benefit for making the amended soil a better habitat for microbes. The impacts of biochar preparation and pollutants nature on PAHs removal were also determined. Significant reduction in the PAHs contents was detected when adding biochar prepared at a high temperature (500°C), while the feedstocks of biochar showed little effect on PAHs removal. Due to the high hydrophobicity of aromatic rings, high-molecular weight PAHs were found much more resistant to microbial degradation in comparison with low-molecular weight PAHs.

Although organophosphate flame retardants (OPFRs) have been shown to accumulate in abiotic and biotic environmental compartments, data about OPFRs concentrations in various foods are limited and are none in humans through diets. In this work, the concentrations of 6 typical OPFRs were investigated in 50 rice samples, 75 commonly consumed foods and 45 human hair samples from China. The dietary intakes of OPFRs for adult people via food ingestion were estimated. The concentrations of ΣOPFRs in foods ranged from 0.004ng/g to 287ng/g. OPFRs were detected in 53.3% of the human hair samples. The highest OPFRs concentrations were found in rice and vegetables. Tri(2-chloroethyl)phosphate(TCEP), tris(2-chloroisopropyl)phosphate(TCIPP), and tri(2-ethyltexyl)phosphate(TEHP) were predominant in all food samples. OPFRs concentrations in foods were not significantly affected by the packaging materials. The mean dietary intakes of ΣOPFRs for adult males and females were 539 and 601ng/kg body weight/day, respectively. The greatest contribution to these values is from rice, accounting for approximately 60% of the total intake, particularly from rice protein. Rice ingestion was considered a potential major pathway for human exposure to OPFRs, and regional differences in the levels of OPFRs in foods and dietary differences should be given more attention in the future.

Characteristics of accumulation and tolerance of cadmium (Cd) in Bidens tripartite L were investigated to identify Cd-accumulating properties. In this study, pot culture experiment and site sampling experiments were conducted to assess whether this plant is a heavy metal hyperaccumulator or accumulator. The results indicated that the Cd enrichment factor (concentration in plant/soil) and Cd translocation factor (concentration in shoot/root) of B. tripartite was principally > 1 in pot culture and concentration gradient experiments. Shoot biomass was not reduced significantly (p < 0.05) compared to the controls. However, the Cd concentration in B. tripartite shoots was not higher than 100 mg kg(-1), the threshold concentration for a Cd-hyperaccumulator. In the site sampling experiment, B. tripartite also showed Cd-accumulator properties. Based on these results, B. tripartite could be identified as a Cd-accumulator. Thus, B. tripartite should only be considered as a Cd-accumulator. (C) 2009 Elsevier B.V. All rights reserved.

Solarium nigrum is a newly found Cd-hyperaccumulator which showed very high remediation efficiency in polluted soil. Seed germination experiments with different illumination and seed-soaking reagents were conducted in constant temperature box and greenhouse with soil as burgeon base. The results showed that the germination rate with alternating light/dark photoperiod was about twice of that without fighting (p l 0.05), suggesting that illumination is one of the important conditions for seed germination of S. nigrum. All treatments with seed-soaking reagents significantly increased the seed germination rate of S. nigrum (p l 0.05). Treatment with H2O2 (0.1%) had the shortest germination time. The germination rate of seeds that were not washed in water following soaking was 2-3 times higher than that of seeds that were washed after soaking. (C) 2009 Elsevier B.V. All rights reserved.

In order to assess ecological risk of pharmaceutical compounds entering into agricultural ecosystems, toxic effects of paracetamol with therapeutic action on wheat (Triticum aestivum L.) were investigated as an example, using early growing and developmental indexes of wheat, including seed germination, shoot height and root length, peroxidase, superoxide dismutase, chlorophyll, and soluble protein in the seedlings. The results showed that wheat shoot and root elongation decreased significantly (p

Phytoremediation of soils contaminated by organic chemicals is a challenging problem in environmental science and engineering. On the basis of identifying remediation plants from ornamentals, the remediation capability of Mirabilis Jalapa L. to treat petroleum contaminated soil from the Shengli Oil Field in Dongying City, Shandong Province, China was further investigated using a field plot experiment carried out in a greenhouse. The results showed that the average efficiency of removing total petroleum hydrocarbons (TPHs) by M. jalapa over the 127-day culture period was high, up to 41.61-63.20%, when the removal rate by natural attenuation was only 19.75-37.92%. The maximum reduction occurred in the saturated hydrocarbon fraction compared with other components of petroleum contaminants. According to the qualitative and quantitative parameters including plant height, fresh weight, dry weight, root length, root weight and visual stress symptoms, it was indicated that M. jalapa had a peculiar tolerance to petroleum contamination and could effectively promote the degradation of TPHs when the concentration of petroleum hydrocarbons in soil was equal to and lower than 10,000 mg/kg. The population of living microorganisms in the planted soil could be also adaptive to

In the current study, Arabidopsis seedlings were hydroponically grown on MS media containing cadmium (Cd) of 0-2.0 mg L(-1) for 60 h of treatment. Gene expression profiles were used to relate exposure to Cd with some altered biological responses and/or specific growth effects. RT-PCR analysis was used to quantitate mRNA expression for seven genes known to be involved in DNA mismatch repair (MMR) system and cell division. Results indicated that Cd concentrations of 0.25-2.0 mg L(-1) cause increased total soluble protein levels in shoots of Arabidopsis seedlings in an inverted U-shaped dose-response manner. Exposure to 0.25 and 0.5 mg L(-1) of Cd dramatically induced expression of four genes (i.e. proliferating cell nuclear antigen 2 (atPCNA 2), MutL1 homolog (atMLH1), MutS 2 homolog (atMSH2) and atMSH3) and five genes (i.e. atPCNA1,2, atMLH1 and atMSH2,7), respectively, in shoots of Arabidopsis seedlings; Exposure to 1.0 mg L(-1) of Cd significantly elevated expression of only two genes (atMSH6,7), but caused prominent inhibition in expression of three genes (atPCNA2, atMLH1 and atMSH3) in shoots of Arabidopsis seedlings. The expression alterations of the above genes were independent of any biological effects such as survival, fresh weight and chlorophyll level of shoots. However, shoots of Arabidopsis seedlings exposed to 2.0 mg L(-1) of Cd exhibited statistically prominent repression in expression of these seven genes, and showed incipient reduction of fresh weight and chlorophyll level. This research provides data concerning sensitivity of expression profiles of atMLH1, atMSH2,3,6,7 and atPCNA1,2 genes in Arabidopsis seedlings to Cd exposure, as well as the potential use of these gene expression patterns as representative molecular biomarkers indicative of Cd exposure and related biological effects.

Joint effects of arsenic (As) and cadmium (Cd) on the growth of Bidens pilosa L. and its uptake and accumulation of As and Cd were investigated using the field pot-culture experiment. The results showed that single Cd (

Recently, researchers are becoming interested in using hyperaccumulators for decontamination of heavy metal polluted soils, whereas few species that hyperaccumulate cadmium (Cd) has been identified in the plant kingdom. In this study, the physiological mechanisms at the seedling stage and growth responses and Cd uptake and accumulation at flowering and mature stages of Bidens pilosa L. under Cd treatments were investigated. At the seedling stage, when soil Cd was lower than 16mgkg(-1), the plant did not show obvious symptom of phytoxicity, and the alterations of chlorophyll (CHL), superoxide dismutase (SOD), peroxidase (POD), malondialdehyde (MDA), and soluble protein (SP) did not have significant differences when compared with the control. At the flowering and mature stages, under low Cd treatments (

Up to now, there was no document on ornamental plants that had been applied to phytoremediation, which can remedy contaminated environment and beautify it at the same time. Thus, the growth responses and possible phytoremediation ability of three ornamental plants selected from the previous preliminary experiments were further examined under single Cd or combined Cd-Pb stress. The results showed that these tested plants had higher tolerance to Cd and Pb contamination and could effectively accumulate the metals, especially for Calendula officinalis and Althaea rosea. For C. officinalis, it grew normally in soils containing 100 mg kg(-1) Cd without suffering phytotoxicity, and the Cd concentration in the roots was up to 1084 mg kg(-1) while the Cd concentration in the shoots was 284 mg kg(-1). For A. rosea, the Cd accumulation in the shoots was higher than that in the roots when the Cd concentration in soils was

Phytoextraction of heavy metal contaminated soils is a promising remediation technology. Till now, more than several hundreds of hyperaccumulators or non-hyperaccumulators which can be used to clean polluted soils with heavy metals have been reported. However, phytoextraction is still not extensively applied. Thus, some measurements should be taken to improve phytoremediation. This paper introduced the basic mechanisms of phytoextration, its main restrictive factors, its relationship with agricultural technology and some agricultural improvement methods. We suggested that unavailable heavy metal activation, crop breeding, seed-coating and felicitous utilization of fertilizer and water, as well as the use of two-phase planting may be important and indispensable paths for phytoextraction to be widely applied at a commercial level in the future.

Long-term field and modeling studies were performed to measure and predict occurrence, accumulation, attenuation and priority of typical antibiotics in sediments of the Dagu River in China. The results indicated that the concentrations of antibiotics ranged from lower than the limit of detection to 12.4mg/kg, depending on the accumulation time of these antibiotics in sediments. Compared with the residential and industrial areas, the agricultural region of the watershed was a major source of antibiotic contamination in sediments. Accumulation and attenuation kinetics models were established and successfully applied in the field study. For instance, by 2100, the accumulation model predicted that the concentrations of roxithromycin and oxytetracycline would rise to 13 and 7.3mg/kg, respectively. The first and second order attenuation kinetics models revealed the fate of these antibiotics along the downstream and upstream sediments, respectively. The half-life distances of antibiotic attenuation ranged from 3.5 to 12.4km. Based on the contamination level and trend, a priority factor and an accumulation growth factor were defined to identify the priority pollutants from the antibiotics. Gentamicin and roxithromycin were recognized as the top priority pollutants among the tested antibiotics. In the future, a wider applicability of the methods and models needs to be explored and suggested.

The contaminations of peptide toxins in drinking water lead directly to sickness and even death in both humans and animals. A smart RNA as aptamer is covalently immobilized on graphene oxide to form a polydispersed and stable RNA–graphene oxide nanosheet. RNA–graphene oxide nanosheets can resist nuclease and natural organic matter, and specifically adsorb trace peptide toxin (microcystin-LR) in drinking water. The adsorption data fit the pseudo-second-order kinetics and the Langmuir isotherm model. The adsorption capacity of RNA–graphene oxide nanosheets decreases at extreme pH, temperature, ionic strength and natural organic matter, but it is suitable to adsorb trance pollutants in contaminated drinking water. Compared with other chemical and biological sorbents, RNA–graphene oxide nanosheets present specific and competitive adsorption, and are easily synthesized and regenerated. Aptamer (RNA) covalently immobilized on graphene oxide nanosheets is a potentially useful tool in recognizing, enriching and separating small molecules and biomacromolecules in the purification of contaminated water and the preparation of samples.

A combined photocatalytic system on one single TiO(2)-nanotube (TNT)/Ti photocatalyst, which was indeed the functional combination of photon-efficient thin-film and conventional bulk-phase photocatalysis processes, was effectively developed in rotating disk photocatalytic reactor for environmental purification applications. The TNT/Ti rotating disk, of uniform size and well-aligned, was successfully prepared by direct anodic oxidation on a dominantly large surface area of 38 cm(2), compared to the typical 1 cm(2) in available literature. To estimate the potentials of combined photocatalytic system for environmental applications, the degradation of rhodamine B was carried out under the optimized conditions, a substrate removal efficiency of nearly 90% and a mineralization efficiency of 56% were observed for initial 20 mg/L solution after 3 h treatment. Compared with the combined photocatalytic system on TiO(2) nanoparticle disk, a significant improvement in substrate removal efficiency of about 25-40% was observed on TNT/Ti disk. It was confirmed that the main degradation of rhodamine B occurred on the upper half of TNT/Ti disk above the heavily colorized sample solution, which was attributed to the superior UV utilization efficiency and the resultant high interfacial photoactivity.

Pot-culture experiments were conducted to investigate the single effect of benzo[a]pyrene (B[a]P) and the joint effect of metal-B[a]P on the growth of Tagetes patula and its uptake, accumulation and dissipation of heavy metals and B[a]P. Results showed that the low concentration of B[a]P (≤10 mg kg(-1)) could facilitate plant growth and resulted in an increase in biomass at the rate of 10.0-49.7% relative to the control. There were significantly positive correlations between the concentrations of B[a]P accumulated in tissues of the plants and soil B[a]P (P

Phytoremediation is a promising green technology for cleanup of petroleum hydrocarbons (PHCs) in contaminated environment. Based on the objective of identifying special ornamental plants for the effective biodegradation of PHCs, the efficacy of Impatiens balsamina L. to phytoremedy petroleum contaminated soil from the Shengli Oil Field in Dongying City, Shandong Province, China, was further examined in a field plot-culture experiment under greenhouse conditions. After a 4-month culture period, the average degradation rate of total petroleum hydrocarbons (TPHs) by the plant was up to 18.13–65.03%, greatly higher than that (only 10.20–35.61%) in their corresponding controls by natural degradation. Among petroleum compositions saturated hydrocarbons had the highest degradation. The release of polar metabolic byproducts during phytoremediation of contaminated soils with ≥20,000 mg/kg of PHCs by I. balsamina may occur. Some growth indexes of I. balsamina indicated that the plant had a good tolerance to contaminated soils with ≤10,000 mg/kg of PHCs. Moreover rhizosphere bacteria and fungi became the dominant microbial population in soils with 5000 and 10,000 mg/kg of PHCs and were probably responsible for TPH degradation. Thus, I. balsamina L. could be a potential ornamental plant for effective phytoremediation of contaminated soils with ≤10,000 mg/kg of PHCs.

Phytoextraction and phytostabilization are well-established sub-processes of phytoremediation that are being followed for in situ remediation of soils contaminated with toxic metals. Taraxacum mongolicum Hand-Mazz, a newly reported Cd accumulator has shown considerable potential for phytoextracting Cd. This paper investigated the effects of urea and chicken manure on T. mongolicum phytoextracting Cd from soil using pot culture experiments. The results showed that urea application did not affect the Cd concentrations in root, leaf, inflorescence and shoot of T. mongolicum, but chicken manure significantly decreased them (p

Surface soil samples from 36 sampling sites including different functional areas in seven districts of Shenyang, China were collected and analyzed. The results showed that the average concentrations of Cd, Cu, Pb and Zn in soil of Shenyang were up to 0.42, 51.26, 75.29 and 140.02mg/kg, respectively, which are much higher than their natural background values. Among the functional areas and administrative regions, the industrial regions and the Tiexi District displayed the highest metal concentrations. Pearson's correlation analysis showed that there existed close correlations among Cd, Cu, Pb and Zn (except for Cd-Cu) at 1% level. Principal Component Analysis (PCA) coupled with correlation between heavy metals revealed that heavy metal contamination might originate from traffic and industrial activities. The values of pollution index (PI) and integrated pollution index (IPI) indicated that metal pollution level was Pb>Cd>Zn>Cu, and Cd, Cu, Pb and Zn belong to moderate or high pollution level. Potential ecological risk indexes (RI) further indicated that Shenyang was suffering from serious metal contamination. These results are important for the development of proper management strategies to decrease non-point source pollution by various remediation practices in Shenyang, China.

Phytoremediation is a cost-effective, simple and sustainable beneficiary technique to purify the polluted environment. Solanum nigrum L., a newly found cadmium (Cd) hyperaccumulator, has shown the potential to remediate Cd-contaminated soils. Present study investigated the effects of fertilizer amendments on the Cd uptake by S. nigrum. Chicken manure and urea are usual agricultural fertilizers and more environmental friendly. The results showed that Cd concentrations in shoots of S. nigrum were significantly decreased (p < 0.05) by 28.2–34.6%, as compared to that of without the addition of chicken manure, but not the case for urea treatment. However, Cd extraction capacities (g pot −1 ) in shoot biomass of S. nigrum were significantly increased (p < 0.05) due to increased shoot biomass. In addition, available Cd concentration in soil significantly decreased due to addition of chicken manure. Thus, urea might be a better fertilizer for strengthening phytoextraction rate of S. nigrum to Cd, and chicken manure may be a better fertilizer for phytostabilization. © 2009 Elsevier B.V. All rights reserved.

Variations in cadmium accumulation and translocation among 40 Chinese cabbage cultivars were studied to identify and screen out Cd-safe cultivars (CSCs), i.e. cultivars with low enough accumulation of Cd in their edible parts even when grown in contaminated soils. It was observed in the pot-culture experiment that there was a significant difference (p < 0.05) in shoot Cd concentrations under three Cd treatments (1.0, 2.5 and 5.0 mg/kg), with corresponding average values 0.88, 4.45 and 7.76 mg/kg, respectively. Shoot Cd concentrations in 16 cabbage cultivars were lower than 0.50 mg/kg. The translocation factors (TFs) and the extraction factors (EFs) in five cabbage cultivars were lower than 1.0 in the pot-culture experiment. The field-culture experiment further validated that New Beijing 3 and Fengyuanxin 3 could be considered as CSCs. In particular, the two cultivars can be cultivated in low to moderate Cd-contaminated soils (Cd concentration

Based on the identification of Mirabilis jalapa L. as a new Cd-hyperaccumulating ornamental, the growth response of the plant to interaction between cadmium (Cd) and phosphorus (P), its effect on the Cd accumulation in the species and relevant mechanisms were further investigated by the pot-culture experiment with chemical analyses and the X-ray absorption near edge structure spectra (XANES). It showed that the leaf, shoot and root biomass (as dry matter) increased with an increase in P supplies from 20 to 100 mg kg(-1) at various tested Cd levels except 10 mg kg(-1). The Cd accumulation in the leaves and shoots significantly decreased with increasing P concentrations from 20 to 500 mg kg(-1) at the Cd concentrations from 10 to 50 mg kg(-1), except the Cd level at 100 mg kg(-1). It was also found that the translocation factor of Cd in M. jalapa L. reached the maximum at different tested Cd levels when the concentration of added P was 100 mg kg(-1), but the bioaccumulation factor of Cd decreased with increasing P. This changing law may be responsible for the mechanism of P immobilizing Cd. The investigation using the P-K edge XANES showed the spectra of adsorbed phosphate in the shoots exhibited a stronger white-line peak than that in the leaves and roots, and the oscillation near 2165eV was more intense. Besides, the P-K edge XANES spectra for M. jalapa L. indicated P may exist as Cd-phosphate. Thus, it can be inferred that the addition of P at appropriate contents may be a useful approach to enhance the plant growth and to immobilize Cd in the Cd-contaminated soil. Furthermore, P and Cd may form a deposit in plants to tolerate Cd toxicity for reducing the degree of the structural damage of the plant.

One of key steps of phytoremediating heavy metal contaminated soils is still the identification of hyperaccumulator and accumulator. In a former published article, Conyza canadensis L Cronq. expressed some basic properties of Cd-hyperaccumulators. In this study, concentration gradient experiment and two sample-analyzing experiments were used to identify whether this plant is a Cd-hyperaccumulator. When grown on soil spiked with Cd at the rate of 10 and 25 mg kg(-1) in concentration gradient experiment, C. canadensis had both Cd enrichment factor (EF) and Cd translocation factor (TF) greater than 1, while the shoot biomass did not differ significantly as compared to the control. On the other hand, with Cd-spiking rates of 10 and 25 mg kg(-1), the Cd concentration in the shoot did not exceed 100 mg kg(-1), which is considered as the minimum shoot Cd concentration to qualify as a hyperaccumulator. In the sample-analysis experiments from a Pb-Zn mine area and wastewater irrigation region, C canadensis also showed Cd-accumulator characteristics. Based on the results accomplished, we propose C. canadensis as a Cd-accumulator. (C) 2008 Elsevier B.V. All rights reserved.

Phytoremediation is a traditional technique that uses vegetation to remediate contaminants from water, soil and sediments. This is a solar-driven, aesthetically pleasing, and cost effective technology. In a former published article, Kalimeris integrifolia Turcz. ex DC. indicated some basic properties of hyperaccumulators for cadmium (Cd). In this study, concentration gradient experiment and sample-analyzing experiments were used to assess whether this plant is a Cd-hyperaccumulator. The results showed the Cd enrichment factor (concentration in plant/soil) and Cd translocation factor (concentration in shoot/root) of K. integrifolia was basically >1 in concentration gradient experiment. Shoot biomass was not reduced significantly (p

Identification of hyperaccumulator and accumulator is still key step of phytoextracting-contaminated soils by heavy metals. In a former published experiment, Taraxacum mongolicum showed basic characteristics of hyperaccumulators. In order to confirm if this plant was a Cd-hyperaccumulator, concentration gradient experiment and sample-analyzing experiments were designed and performed. The results showed that Cd enrichment factor and Cd transformation factor of T.mongolicum were all higher than 1 in concentration gradient experiment. The shoot biomasses did not reduced significantly (p < 0.05) compared with the control without Cd added under the conditions of lower than 25 mg kg(-1) Cd spiked into soil. However, Cd concentration in shoot of T.mongolicurn was not higher than 100 mg kg(-1) the minimum a Cd-hyperaccumulator should have under the conditions of any concentration level of Cd spiked. Thus, T mongolicum should be a Cd-accumulator. In the sample-analyzing experiments settled in a Pb-Zn mine area and Shenyang wastewater irrigation region, T. mongolicum also showed that Cd-accumulator characteristics. Based on these results, T mongolicum could be identified as a Cd-accumulator, which may have important implication in plant physiology and gene engineering. (C) 2008 Elsevier B.V. All rights reserved.

Hyperaccumulators are ideal plant species used for phytoremediation of soils contaminated by heavy metals. A full understanding of metal tolerance mechanisms of hyperaccumulators will facilitate enhancing their phytoremediation efficiency. However, how Cd affects N metabolism and which role plays the response of N metabolism to Cd toxicity in the tolerance of hyperaccumulators are still unknown. To clarify these questions, this study investigated the effects of various soil Cd levels on the concentrations of N forms and the activity of key enzymes involved in N metabolism in leaves of the Cd hyperaccumulator, Solanum nigrum L. The results showed that its growth and all N metabolism indicators were normal at low Cd exposure (

Chelate-enhanced phytoremediation is considered as an effective method for the extraction of lead (Pb) by plants. However, more detailed studies are needed to evaluate the effect of exogenous chelators on phytoavailability and toxicity of Pb in plants, then to find out the proper applied concentration of chelators to minimize the combined toxicity to the plants and maximize phytoavailable Pb. To clarify these questions, the seed germination test of Zinnia elegans Jacq. exposed to solutions containing Pb and four types of chelators including sodium ethylenediamine tetra-acetic acid (Na2EDTA), oxalic acid, tartaric acid and citric acid was observed. The results showed that the roots and shoots treated with equimolar chelators and Pb were longer than those treated with half and two folds of the molar concentrations of Pb. The growth of seedlings was inhibited by surplus addition of chelators, and the toxicity of complexes was less than that of Pb and chelators. In particular, 2.4 mM EDTA and 1.2 mM oxalic acid significantly (P