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Crops grown in areas contaminated by industrial and agricultural fluorine (F) have gained increasing attention, however F levels in different vegetables and lettuce cultivars are rarely reported. In situ-field experiment was designed to investigate the concentration, translocation, and health risks of F in 20 vegetable species and 25 lettuce cultivars. After the growth of 150 d for vegetables and 60 d for lettuce, F concentration (12.83-138.07 mg kg

Continuous cropping obstacle (CCO) in tobacco is a prevalent and intractable issue and has not yet been effectively solved. Many researchers have favored exploring environmentally friendly and sustainable solutions to CCO (e.g, the application of (bio-) organic fertilizers). Therefore, to study the effects of functional organic fertilizers (FOFs) on tobacco CCO, we applied five types of fertilizers in a tobacco continuous cropping field with red soil (i.e., CF: tobacco-special chemical fertilizers; VOF: vermicompost-based FOF; HOF: humic acid-based FOF; WOF: wood biochar-based FOF; COF: compound FOF). The tobacco plant agronomic traits, leaf yield, economic value, and chemical quality (nicotine, total sugar, K2O, Cl contents, etc.) were evaluated via the continuous flow method. Meanwhile, we determined rhizosphere soil physicochemical properties, phenolic acids content, and bacterial community diversity by high-throughput sequencing. The results show that FOFs improved the tobacco plant agronomic traits, leaf yield (by 2.9–42.8%), value (by 1.2–47.4%), and chemical quality when compared with CF. More content of NH4+-N, available P, and available K were discovered in the rhizosphere soil in VOF, HOF, and WOF. The rhizosphere sinapic acid and total phenolic acids content declined in the FOF treatments (1.23–1.56 and 7.95–8.43 mg kg−1 dry soil, respectively) versus those in the CF treatment (2.01 and 10.10 mg kg−1 dry soil, respectively). Moreover, the rhizosphere bacterial community structure changed under FOF functions: the beneficial microbes Actinobacteria, Firmicutes, Streptomyces, and Bacillus increased, and the harmful microbes Acidobacteria and Gemmatimonadota decreased in abundance. There was a positive correlation between the tobacco leaf yield and soil NH4+-N, TC content, and the relative abundance of Proteobacteria and Actinobacteriota. In summary, the application of VOF and WOF is a modest, practical, and environmentally friendly strategy to alleviate tobacco CCO from the standpoint of recycling solid waste.

Continuous cropping obstacle (CCO) in tobacco is a prevalent and intractable issue and has not yet been effectively solved. Many researchers have favored exploring environmentally friendly and sustainable solutions to CCO (e.g, the application of (bio-) organic fertilizers). Therefore, to study the effects of functional organic fertilizers (FOFs) on tobacco CCO, we applied five types of fertilizers in a tobacco continuous cropping field with red soil (i.e., CF: tobacco-special chemical fertilizers; VOF: vermicompost-based FOF; HOF: humic acid-based FOF; WOF: wood biochar-based FOF; COF: compound FOF). The tobacco plant agronomic traits, leaf yield, economic value, and chemical quality (nicotine, total sugar, K

Single or combined plant growth-promoting bacteria (PGPB) strains were widely applied as microbial agents in cadmium (Cd) phytoextraction since they could promote plant growth and facilitate Cd uptake. However, the distinct functional effects between single and combined inoculants have not yet been elucidated. In this study, a field experiment was conducted with single, double and triple inoculants to clarify their divergent impacts on plant growth, Cd uptake and accumulation at different growth stages of

Previous studies have focused on total cadmium (Cd) accumulation in rice or its transformation in soil, but only a few have examined the entire soil-rice-human system. This study investigated the Cd bioaccessibility and bioavailability for humans from grains of early rice cultivars grown in a Cd-polluted field and further combined with multi-traits to discover and evaluate the optimum safe production and phytoremediation potential cultivars. The results revealed that Cd concentration in polished rice was0.20 mg kg

Aims: For a metal hyperaccumulator plant Sedum alfredii, the recruitment of unique rhizospheric bacterial communities from bulk soils has been well studied. However, in the root-soil interface, the knowledge on the establishment of endospheric microbiomes from rhizospheric soil is still scarce. Methods: In this study, we combined culture-independent that was 16S rRNA gene amplicon sequencing, and culture-dependent methods that included bacterial isolation, heavy metal tolerance and plant growth-promoting traits. Results: The Cd/Zn concentrations in endosphere were significantly higher than in soil, while Pb concentration in endosphere was significantly lower than in soil. The α-diversity in rhizosphere soils was higher than in root endosphere, and the compartments as a major determinant revealed 85.9% of the taxa variations. The relative abundance of Proteobacteria increased in endosphere compared to rhizosphere. The difference of Cd/Zn tolerance between endospheric and rhizospheric isolates was not obvious, while the Pb tolerance of endospheric isolates significantly decreased compared to rhizosphere. Conclusions: The results suggest that S. alfredii recruits Cd/Zn-tolerant but not Pb-tolerant endospheric bacterial communities from its rhizospheric soil. The difference in the microbial structure and function in the root-soil interface might be related to the selective absorption of metals in S. alfredii.

The papers in this dedicated issue of the International Journal of Phytoremediation were presented at the 16th Conference of the International Phytotechnology Society (IPS) which was hosted by the ...

Information is needed for comparative assessment and agronomic practices for phytoavoidation in multi-pollutant field. A field study was conducted to explore 97 Brassica pekinensis L. genotypes with permissible limit of contaminants growing in a severely Cd, moderately nitrate and slightly Pb multi-polluted field. Thirteen genotypes, i.e. KGZY, CXQW, CAIB, JINL, JQIN, JFEN, WMQF, XLSH, TAIK, BJXS, JUKA, XYJQ and GQBW, were identified with permissible limit for nitrate, Cd and Pb based on their resistance to heavy metal and nitrate accumulation in leaves when grown in co-contaminated soils. Furthermore, the correlation between essential and toxic elements concentrations in plant of B. pekinensis were inconsistent. Generally speaking, application of increasing Ca, K and S fertilizers in appropriate forms and dosages tended to increase the yield and quality of B. pekinensis cultivated in multi-pollutant field.

Hydrothermal carbonization (HTC) has drawn increasing interest for the disposal of solid wastes with a high moisture content, while minimal attention has been paid to HTC treatment of wetland plants and the corresponding phosphorus (P) transformation. In order to evaluate its feasibility for wetland plants treatment, hydrochars from different wetland plants were produced at different temperatures (200 °C, 220 °C, 240 °C, and 260 °C) and characterized, and the transformation of P was investigated. In comparison with wetland plant derived biochars, the derived hydrochars had a moderate pH (5.0–7.7), more oxygen-containing groups, and higher energy density (18.0–27.1 MJ kg−1). These properties were affected by hydrothermal temperature and feedstock choice. In contrast to high water-soluble P in biomass (71.0–73.2% of total P), more recalcitrant P species formed in hydrochars, implying that HTC treatment could achieve P immobilization and reduce P leaching loss. Nuclear magnetic resonance (NMR) results indicated that monoester-P and soluble orthophosphate were transformed to insoluble orthophosphate during the HTC treatment. Therefore, HTC is a promising treatment technique for wetland plants to produce valuable char with P reclamation.

An integrated constructed wetland (ICW) with six subsystems has been operated for six years (60,000 Ton day−1) and exhibited strong stability and high efficiency for removing conventional pollutants in tail water. This study was aimed to characterize the removal efficiency of antibiotics in relation to bacterial community structure and composition in this integrated constructed wetland. Water samples were taken from different ICW sites in two distinct seasons (i.e. winter and summer). The results showed that concentrations of antibiotics in ICW decreased from influent to effluent with varying removal rates among the different antibiotics (quinolones, ulfonamides and macrolides). The pyrosequencing of 16S ribosomal DNA revealed that the composition of dominant phyla could be grouped into four bacterial clusters and the key discriminant phyla, family or genera from each cluster was strongly associated with the specific physicochemical parameters of water or type of antibiotics. Members of the key phyla (Proteobacteria, Bacteroidetes, Parcubacteria, and Actinobacteria) appeared to play an important role in antibiotics removal. In general, both the concentration of antibiotics and physicochemical parameters of water shaped the bacterial communities. These results improve our understanding of the interactions between antibiotics or water physiochemical parameters and bacterial communities in the integrated constructed wetland.

The willow (Salix spp.) is a potential accumulator of cadmium (Cd)/zinc (Zn), and the interaction between Cd and Zn is an important factor influencing their phytoextraction potentials. In this study, interactions between Cd and Zn in uptake, accumulation and bioavailability for Salix integra clone SI63 were investigated through nutrient solution and soil culture methods. The result of the soil culture showed that Cd had additive effects for Zn-caused biomass reduction. The result from nutrient solution indicated that added Zn showed antagonistic (low Cd level) or synergistic (moderate and high Cd levels) effects on shoot Cd accumulation and antagonistic effects on root Cd accumulation. Irrespective of nutrient solution or soil culture experiment, Cd addition always had antagonistic effects on Zn accumulation in both shoots and roots. Under Cd10Zn50 condition, the clone accumulated higher Cd and Zn concentrations (95 μg g−1 Cd and 165 μg g−1 Zn) in shoots. Cd slightly increased bioavailable Zn in the rhizosphere, and EDTA well predicted bioavailable Cd and Zn in the rhizosphere. Interactions of Cd–Zn markedly changed their respective phytoextraction potentials, especially for Zn. This result will provide a new insight into improving phytoextraction potentials of both Cd and Zn using willows through applying metal interactions.

Soil organic matter (SOM) is of vital importance to soil health, and also plays a crucial role in the quality of the crops such as tobacco. However, the link between tobacco quality and SOM chemical compositions is still not well understood. To fill the information gap, we analyzed the quality of tobacco leaves and the corresponding SOM molecular compositions by electrospray ionization (ESI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), that were collected from six different sites in Bijie, Guizhou Province, China. The tobacco quality varied in six sites based on their chemical compositions. SOM compounds had a remarked impact on the quality of tobacco leaves and a distinct difference in SOM composition between low-quality and high-quality tobacco leaves was observed as well. Specifically, 105 common molecular formulas were detected in three SOM compounds of high-quality tobacco, which were more than those in low-quality samples. Although amino sugar, proteins, lipids, tannins, and carbohydrates had a collective influence on the chemical composition of tobacco leaves, the effect contributed by amino sugar and tannins was more prominent. In summary, fully understanding the association between tobacco chemical composition and SOM compounds can provide new insight into the regulation of tobacco quality and the sustainable development of agriculture.

Sustainable strategies are essential for zinc (Zn) biofortification and cadmium (Cd) reduction in staple food crops. Herein, we evaluated the phytotoxicity of Glyzinc under foliar and root application (FARA) in a lab-scale experiment, and then investigated its Zn efficiency and Cd reduction through foliar application on wheat (Triticum aestivum L.) under field conditions. Compared to RA, FA of Glyzinc exhibited no adverse effect on wheat growth and oxidative stresses at all doses. In field conditions, FA of Glyzinc remarkably increased Zn (28.7 %), S (10.4 %), Cu (17.3 %) and crude protein (9.1 %) content in wheat grain at 100 mg/L without damaging wheat yield. Furthermore, FA of Glyzinc significantly reduced the grain phytic acid (PA) (23.7 %) and Cd level (19.5 %), as well as PA to Zn molar ratio (32.3 %). Overall, our results indicate that Glyzinc has great potential as a high-efficiency foliar fertilizer for Zn biofortification and safe crop production in nano-enabled agriculture.

An acidified magnetic sludge-biochar (MSB) was prepared to enhance ammonium nitrogen (AN) removal efficiency in eutrophic water, and MSB was obtained by secondary pyrolysis of sludge biochar powder. A series of MSB were prepared under 300, 400, 500, 600 °C and different valence states of iron ions by impregnation pyrolysis, which is based on the deposition of unstable iron minerals on biochar matrix. Physicochemical properties of pristine biochar and MSB were revealed through characterization analysis, suggesting that MSB prepared by ferric chloride at 400 °C presented the largest adsorption capacity, and the acid-modification enhanced the ammonium adsorption capacity by 10.7%. Electrostatic attraction and ion-exchange processes were identified as the main adsorption mechanisms of MSB on AN. As the most dominant mechanism, ion exchange of AN with functional groups containing -OH and CO on the surface of MSB resulted in the relative content of -OH (61.3%) and CO (11.5%) bonds reduced to 34.2% and 7.0% respectively. The novel magnetic sludge-biochar with acid-modification possessed enhanced electron transfer capacity, revealing a removal pathway of ammonium by nitrification. The findings above demonstrated that MSB is a promising adsorbent for ammonium removal and can be applied to the natural nitrogen-rich water regulation.

Cadmium (Cd) and fluorine (F) often coexist in environment and are toxic to organisms; however, their combined effects on plants are still not well documented. In this study, the co-effects of Cd and F on germination, biomass, photosynthesis, and nutrients uptake of lettuce were carried out in hydroponic culture. The results showed that the seed germination and seedling biomass decreased with an increase in Cd and F supplementation. The root morphology verified these effects as excess combined Cd and F diminished the root tips and surface area of lettuce, while single Cd and F inhibited the growth by decreasing root length and average diameter, respectively. These effects were also consistence with a reduction in photosynthesis which was mainly regulated by reducing the quantum yield of PS II, electron transport activity, stomatal conductance, intercellular CO

Soil pollution caused by potentially toxic metals has become a worldwide environmental issue. Geogenic processes and anthropogenic activities are two important sources of soil pollution. Soils may inherit toxic metals from parent materials; however, soil pollution mostly results from industrial and agricultural activities. Contamination by metals can be indicated by the changes in chemical, biochemical, and microbial properties of soils and plant responses. The total concentration of toxic metals in soil is still the most widely used indicator for risk assessment although extractable amounts have been reported to be more closely related to plant uptake. Several models have been proposed for assessing soil contamination by toxic metals, but none of them are commonly accepted for application to a wide range of soils. This review paper highlights how toxic metal contamination negatively affects soil and environmental quality, impacts food quality and security, and poses a threat to human health. Further research is needed to not only improve soil contamination diagnosis, modeling, and regulatory standards but also for remediation efficiency.

Continuous cropping obstacle (CCO) is a common phenomenon in agricultural production and extremely threatens the sustainable development of agriculture. To clarify the potential keystone factors causing tobacco (

In this study, Rhizobium rhizogenes-mediated root proliferation system in Sedum alfredii has been established. Twenty strains of R. rhizogenes were screened for root proliferation. A significant difference (P0.01) was observed in plant morphological characters under influence of different bacterial strains. The highest root fresh weight (3.236 g/plant) was observed with strain AS12556. Furthermore, significant difference (P0.05) was observed in the chemical composition of organic acids, Tartaric acid (TA), Succinic acid (SA), Malic acid (MA), Citric acid (CA) and Oxalic acid (OA), pH, Total Nitrogen (TN), Total Organic Carbon (TOC) and soluble sugars in root exudates with different R. rhizogenes mediated roots. Furthermore, a series of hydroponics experiments were conducted with varying concentrations of Cd (25, 50 and 75 µM) and Zn (100, 200 and 500 µM) to assess the phytoextraction efficiency of proliferated roots with Rhizobium. Several plants with proliferated roots showed enhanced growth and improved metal extraction efficiency. Five strains (LBA 9402, K599, AS12556, MSU440 and C58C1) were identified as potential strains for root proliferation in Sedum alfredii. R. rhizogenes strain AS12556 improved Cd/Zn phytoextraction by exogenous production of phytochemicals to promote root proliferation, improved shoot biomass, lowered oxidative damage and enhanced phytoextraction efficiency in S. alfredii. Therefore, it has been selected as a potential microbial partner of S. alfredii to develop extensive rooting system for better growth and enhanced phytoremediation potential. Results suggest that R. rhizogenes mediated root proliferation system can be used for optimizing metal extraction from contaminated soils.

Straw residues, as one of the conservation farming practices, are being strongly encouraged in China, including some cadmium-polluted areas. Nowadays, a portion of this plant residue is promoted to be removed for reducing excess metal(loid) in the soil and to be used for bioenergy production. Nevertheless, the possible influences of contaminated straw or the burial of its derived biochars on Cd accumulation in soil and data based on health risk assessment associated with different status and extent of soil contamination were relatively unknown. Thus it is important to provide a more systematical understanding of contaminated straw burial at specific contamination zones, which may provide useful guidance for straw utilization. In this study, we harvested two genotypes of rice straw from 6 contaminated levels among three soil types to comprehensively study the total Cd contents in straws and its derived biochars and correlate the sets of straw characteristics and Cd contents in three different contamination zones. The total Cd concentration in straws grew at a steady rate relatively with increasing soil Cd contamination levels, compared to those in biochars which performed more fluctuate due to the strong burning. According to correlational analyses, three-way ANOVA showed that the moisture, ash, volatile and fixed carbon were all significantly affected by straw CdTotal contents (p

Sedum alfredii Hance is a cadmium (Cd)/zinc (Zn) hyperaccumulator native to China. However, its relatively low biomass restricted the large-scale application for heavy metal contamination remediation. The chromosome set doubling of S. alfredii in vitro was achieved by 0.1%-0.2% (W/V) colchicine treatment. The plant DNA ploidy was analyzed by flow cytometry and chromosome set doubling plants (CSD) were identified based on the obvious different sharp peak. A tissue culture experiment with different Cd treated levels and a field trial with natural polluted mined soil were conducted to study the effects of chromosome doubling on plant biomass and Cd accumulation in shoots. The results suggested that S. alfredii is a mixoploid. Compared with the wild type plants (WT), CSD exhibited typical "gigas" characteristics in morphology including stem thickness, root hair production, number of leaves and size of stoma guard cell. Fresh weight and dry weight of CSD were increased to 1.62-2.03-fold and 2.26-3.25-fold of WT. And Cd content of CSD showed a 17.49%-42.82% increase and 59% increase under tissue culture and field condition, accordingly. In addition, the TF and in BCF of CSD were 2.37- and 1.59-fold of WT, respectively. These results proved that it is feasible to promote phytoextraction efficiency of S. alfredii in Cd contaminated soils through chromosomal engineering, which provides a novel approach for hyperaccumulator application in phytoremediation.

In vitro oral bioaccessibility of Cadmium (Cd) in two low (XGSJ), (SHQI) and two high (CGBC), (SIYM) Cd-accumulating affinity cultivars of Brassica rapa ssp. chinensis L. (pak choi) grown o...

Plant growth promoting bacteria (PGPB) have been reported to have the ability to promote plant growth, development and increase heavy metals (HMs) uptake. Therefore, PGPB inoculation as soil remediation agents into plants with larger biomass and potential of phytoextraction is of great importance to increase bioremediation efficiency. In this study, 12 PGPB strains isolated from a cadmium (Cd)/zinc hyperaccumulator Sedum alfredii Hance were inoculated into non-host plant Brassica juncea and their effects on plant growth and Cd uptake were determined. The results showed that inoculation of most PGPB strains promoted plant growth, boosted root development and improved chlorophyll content in the absence of Cd. Inoculation of PGPB strains promoted plant growth up to 111% in shoot and 358% in root when treated with 2 μM Cd. In addition, PGPB inoculation not only ameliorated plant root morphology including the total root length (RL), total surface area (SA), total root volume (RV) and number of root tips (RT), but also facilitated Cd uptake up to 126%. Furthermore, inoculation of PGPB strains promoted plant Cd accumulation up to 261% in shoot and up to 8.93-fold increase in root. Among all the 12 PGPB strains, Burkholdria SaMR10 and Sphingomonas SaMR12 were identified as the promising microbes for improving phytoremediation efficiency of Cd contaminated soils. These results not only provided useful findings for further investigation of interacting mechanisms between different bacterial strains and plants, but also facilitated the development of microbe-assisted phytoremediation application for HM contaminated soil.

Tetracycline (TC) can enter the human body via the soil-vegetable-human food chain; therefore, it is necessary to understand the toxicity of TC to humans through vegetables grown on contaminated soils. The present study combined an enzyme-linked immunosorbent assay method and an HL-7702 cell model and assessed the bioavailability and toxicity of TC from pak choi (Brassica campestris L. ssp. chinensis) grown on TC-contaminated soils. The results showed that the degradation rate of TC in black soil was significantly higher than that in purplish clay, while the results for TC uptake in pak choi were opposite. The bioaccessibility of TC was found to be higher in pak choi grown on purplish clay (5.67–7.59%) than in that grown on black soil (5.22–6.77%). It is suggested that soil properties contribute to the uptake of TC by pak choi. More fertile soil contained lower TC concentrations and thus mediated lower TC toxicity to humans. It may seem comforting that TC concentrations in the edible parts of pak choi are often found to be below safe limits. However, the TC diagnosis method showed that even moderate increases in TC concentrations in pak choi may induce oxidative stress, liver injury, mitochondrial cristae and rough endoplasmic reticulum swelling, and early apoptosis in liver cells HL-7702. The pak choi grown in purplish clay showed higher TC cytotoxicity than that grown in black soil. The TC cytotoxicity of raw pak choi was found to be higher than that of cooked pak choi. These results provide direct evidence of effective ways to prevent TC toxicity in humans.

The willow (Salix spp.) is a promising candidate coping with global climate warming and environment pollution. In this study, differences in plant growth, Cd uptake and accumulation, and extractable Cd in the rhizosphere between flooded and non-flooded (well-drained) Salix genotypes were investigated using a pot experiment in the rainshelt. All Salix genotypes grew well under well-drained conditions. In contrast, the flooded Salix genotypes developed hypertrophied lenticels, adventitious roots and aerenchyma, and decreased aboveground biomass production compared with the corresponding non-flooded genotypes, varying with genotypes and Cd levels in the medium. The non-flooded Salix genotypes had high Cd accumulation in aerial tissues with high leaf Cd bioconcentration factors (BCF) and translocation factors (TFs) relative to genotypes, displaying good Cd phytoextraction potentials. The flooded Salix genotypes dramatically decreased Cd accumulation in aerial tissues with low Cd BCFs and TFs, and large amounts of Cd accumulated in roots compared to the non-flooded genotypes, showing Cd phytostabilization traits. The extractable Cd in rhizosphere changed with genotypes and treatments, and comparatively, EDTA-extractable Cd could reflect well Cd phytoavailability to the willows in the soil. It was concluded that flooding tended to shift from phytoextraction to phytostabilization for Cd by willows during whole growing season.

The reclamation of phosphorus (P) in wetland biomass is a potential strategy to alleviate the P resource shortage, and (hydro)thermal treatment is considered a promising technique for biomass waste...

Heavy metals contamination in agricultural soil has become a worldwide problem, and soil characteristics modulate metal availability in soils. Four field experiments were conducted simultaneously to evaluate concentration and distribution of cadmium (Cd) and lead (Pb) in 39 oilseed rape cultivars at four agricultural locations with different contamination levels of Cd and Pb, as well as the influence of soil characteristics together with soil total and bioavailable Cd and Pb concentration on metal transfer from soil to oilseed rape. Shoot concentrations of Cd and Pb in oilseed rape cultivars ranged from 0.09 to 3.18 and from 0.01 to 10.5 mg kg−1 across four sites. For most cultivars, Cd concentration in root or shoot were higher than pod and lowest in seed, while the highest Pb concentration was observed in root followed by shoot and seed. Stepwise multiple linear regression analysis allows for a better estimation of Cd and Pb concentration in oilseed rape while taking soil properties into consideration. The results demonstrated that Cd and Pb concentration in oilseed rape were correlated with soil organic matter (OM), cation exchange capacity (CEC), available phosphorus (AP), available potassium (AK), sand, soil total and available Cd and Pb concentration, and R2 varied from 0.993 to 0.999 (P

Sedum alfredii Hance is a hyperaccumulator of cadmium (Cd) and zinc (Zn) that exhibits extraordinary accumulation of these metals in various tissues. The Nicotianamine synthase (NAS) genes play key roles in regulating the production of nicotianamine, a non-protein amino acid that facilitates metal homeostasis in plants, but the functions of these genes in S. alfredii remain unknown. The aims of this study were to identify and characterize the NAS gene from S. alfredii (SaNAS1) and explore NAS roles in Cd or Zn tolerance and accumulation. One Cd-induced NAS gene from S. alfredii (SaNAS1) was cloned. We determined the subcellular localization of the encoded protein and evaluated SaNAS1 expression. We also assessed SaNAS1 function by conducting a complementary assay with yeast mutants Δzrc1 exposed to Cd or Zn. Finally, transgenic Arabidopsis plants expressing SaNAS1 were produced, and SaNAS1 function was further examined in these plants. SaNAS1 was highly expressed in response to Cd or Zn exposure, and the encoded protein was distributed throughout the cytoplasm and nucleus. Furthermore, yeast expressing SaNAS1 exhibited increased tolerance to Cd or Zn. Finally, expression of SaNAS1 in Arabidopsis increased nicotianamine production and promoted Cd or Zn accumulation in roots and shoots. SaNAS1-expressing transgenic Arabidopsis lines showed improved seedling growth under Cd or Zn stress compared with wild type, indicating that SaNAS1 enhances tolerance to both Cd and Zn. SaNAS1 may play a critical role in Cd or Zn tolerance and hyperaccumulation by regulating nicotianamine level in S. alfredii.

Spinach (Spinacia oleracea L.) is an important leafy vegetable, rich in various essential nutrients required for human health. However, it may also accumulate hazardous materials in edible parts, and subsequently poses human health risk. Evaluation of variation in essential nutrients and hazardous materials in spinach genotypes is important for breeding desired genotypes for human consumption. In this study, we investigated 68 spinach genotypes for screening desired genotypes. Seven spinach genotypes, i. e. KBXX, XIBW, KBWZ, DBSC, LLCJ, QUAN and JXQD were identified as safe genotypes that contained contaminants in edible parts below permissible limit (Cd

Comparative impact of CO2 application and endophyte inoculation was investigated on the growth, rhizosphere characteristics, and cadmium (Cd) absorption of two ecotypes of Sedum alfredii Hance in response to Cd stress under hydroponic or rhizo-box culture conditions. The results showed that both CO2 application and endophyte inoculation significantly (P

Rapid industrialization in China accelerated environmental pollution by xenophores and trace metals particularly cadmium. Numerous studies have been conducted to address soil contamination using organic and inorganic amendments under pot or incubation conditions, but few were performed under field conditions, particularly in the wheat-growing areas. This study aims to investigate the effectiveness of pre-applied soil amendments for Cd immobilization, changes in soil pH, and metal uptake by wheat. In this study, 12 treatments, i.e., control (CK), lime, DaSan Yuan (DASY), DiKang No. 1 (DEK1), biochar, Fe-biochar, Yirang, CaMgP, and green stabilizing agents (GSA-1, GSA-2, GSA-3, and GSA-4), were evaluated for Cd immobilization in incubation and field experiments. Changes in soil pH and available metal content with amendments were monitored from 30 to 150 days of incubation. Single extraction method and DTPA-extractable and sequential extraction procedures were employed to assess the variations in available Cd contents of field soil. The impact of soil amendments on Cd uptake and bioaccumulation in food part of wheat was measured at harvesting stage in a contaminated site. Lime treatment increased soil pH by 32% and reduced available Cd to 0.213 mg kg−1, as compared to CK (control) in the incubation experiment (0.343 mg kg−1). Effects of the amendments on wheat growth, soil pH, and Cd phytoavailability were reported. Wheat biomass was highest in treatment GSA-2 (13,880 kg ha−1) and GAS-4 resulted in an increase in grain yield (5350 kg ha−1). Soil pH of the treated field at harvesting stage increased up to 6.50, 6.50, and 6.47 by application of GSA-4, GSA-2, and lime, respectively. Cadmium contents in wheat grain were declined significantly in the treatments of GSA-2, GSA-4, and lime. Results of this study revealed a significant decrease in available Cd concentration with the application of amendments. Composite amendments were more effective in terms of metal uptake and bioaccumulation in wheat. In addition, our results indicate the effectiveness of composite amendments in stabilizing Cd in contaminated soil.

Cadmium contamination in soil, water and food has become a global problem since last century's industrial and agricultural revolution. It is a highly toxic metal with serious consequences on human and animal health. Different natural and anthropogenic sources are responsible for Cd release in the soil which ultimately leads to the food chain. Cd persists in soil for long durations due to its minimal microbial or chemical loss. There are various physical, chemical or biological techniques which are helpful to minimize Cd risk in food chain. Among them, in-situ immobilization with organic, inorganic or clay amendments is a cost-effective and an environment friendly strategy to remediate Cd polluted sites. Lime, biochar, organic wastes, phosphorus fertilizers, sepiolite, zeolite, hydroxyapatite and bentonite are commonly used amendments for amelioration of Cd contaminated soils. These amendments reduce Cd uptake and enhance immobilization by adsorption, complexation, and precipitation processes. This review is aimed to provide a comprehensive note on Cd toxicity in humans and environment, its immobilization by different agents through variety of processes, and comparison of technologies for Cd removal from contaminated sites.

The identification of high yield genotypes that are capable of accumulating multiple heavy metals in the non-edible parts (roots and shoots), but not in the edible parts (seeds) and have desired nutritional value is necessary for accomplishing phytoremediation coupled with agro-production. In this study, 17 fava bean genotypes were screened in two different field conditions to examine their phytoremediation potential in terms of uptake and translocation of Cd and Pb. Ten genotypes, LBAO, JNJX, DCAN, QXCJ, QIKM, LXYC, YDL6, RBCD, QPID and ZHW6 were found as the best accumulators for Cd and Pb with permissible limit of metals in seeds. The concentration of plant nutrients were genotype and soil type dependent and there was a significant correlation between these two factors. Furthermore, the three genotypes DCAN, LBAO and LXYC showed best performance in alluvial soil type while QPID, RBCD and LXYC were the best in red soil type. Genotype LXYC was similar for both soil types and appeared to be the best fit for phytoremediation coupled with agro-production for slightly or moderately Cd and Pb co-contaminated soil. Therefore, fava bean LXYC genotype is suggested as a potential candidate for phytoremediation of Cd/Pb co-contaminated soils coupled with agro-production.

A granular composite sorbent (LC-CF) was synthesized from acid-leached carbon waste using chitosan and FeCl3, and its feasibility for nitrate and phosphate removal was investigated in this study. The sorption data was well described by the pseudo-second-order kinetic model, and the maximum sorption capacity of LC-CF predicted by Langmuir model for nitrate and phosphate were 41.90 mg g−1 and 62.72 mg g−1, respectively. In comparison, LC-CF had a greater affinity for phosphate and exhibited a better reusability for nitrate removal during the sorption-desorption cycles. Ion exchange, electrostatic interaction, and hydrogen bond are the potential sorption mechanisms. In light of the cost-benefit analysis, the proposed treatment of carbon waste was more economically feasible as compared with existing incineration scheme. These results illuminated that synthesis of granular sorbent with carbon waste could achieve the harmless disposal of hazardous industrial waste as well as the production of value-added sorbent for water treatments.

Biochar (BC) has been recognized as an effective adsorbent to remove trace elements (TEs) from water. However, low surface functionality and small pore size can limit the adsorption ability of pristine biochar. These limitations can be addressed by using functionalized biochars which are developed by physical, chemical, or biological activation of biochar to improve their physico-chemical properties and adsorption efficiency. Despite the large amount of research concerning functionalized biochars in recent decades, to our knowledge, no comprehensive review of this topic has been published. This review focuses solely on the synthesis, characterization, and applications of functionalized/engineered biochars for removing TEs from water. Firstly, we evaluate the synthesis of functionalized biochars by physical, chemical, and biological strategies that yield the desired properties in the final product. The following section describes the characterization of functionalized biochars using various techniques (SEM, TEM, EDS, XRD, XANES/NEXAFS, XPS, FTIR, and Raman spectroscopy). Afterward, the role of functionalized biochars in the adsorption of different TEs from water/wastewater is critically evaluated with an emphasis on the factors affecting sorption efficiency, sorption mechanisms, fate of sorbed TEs from contaminated environments and associated challenges. Finally, we specifically scrutinized the future recommendations and research directions for the application of functionalized biochar. This review serves as a comprehensive resource for the use of functionalized biochar as an emerging environmental material capable of removing TEs from contaminated water/wastewater.

Constructed wetland is considered a promising approach for water remediation due to its high efficiency, low operation costs, and ecological benefits, but the large amounts of wetland plant biomass need to be properly harvested and utilized. Recently, wetland plant derived biochar has drawn extensive attention owing to its application potential. This paper provides an updated review on the production and characteristics of wetland plant derived biochar, and its utilization in soil improvement, carbon sequestration, environmental remediation, and energy production. In comparison to hydrothermal carbonization and gasification, pyrolysis is a more common technique to convert wetland plant to biochar. Characteristics of wetland plant biochars varied with plant species, growth environment of plant, and preparation conditions. Wetland plant biochar could be a qualified soil amendment owing to its abundant nutrients. Notably, wetland plant biochar exhibited considerable sorption capacity for various inorganic and organic contaminants. However, the potentially toxic substances (e.g. heavy metal and polycyclic aromatic hydrocarbons) retained in wetland plant biochar should be noticed before large-scale application. To overcome the drawbacks from the scattered distribution, limited productivity, and seasonal operation of constructed wetlands, the economic feasibility of wetland plant biochar production system could be improved via using mobile pyrolysis unit, utilizing local waste heat, and exploiting all the byproducts. Future challenges in the production and application of wetland plant derived biochar include the continuous supply of feedstock and proper handling of potentially hazardous components in the biochar.

Climate-related flooding poses a potential challenge to phytoremediation of metal polluted areas. In the present study, uptake, translocation and accumulation of heavy metals (Cd, Zn and Cu), and their phytoavailability in six flood-tolerant Salix genotypes were investigated under simulated seasonal flooding conditions (non-flooding conditions were kept as the control). Plants were cultivated in a greenhouse with open windows using the soil polluted with Cd, Zn and Cu for 110 days. All the control (non-flooded) genotypes did not exhibit visible toxic symptoms, whereas the flooded genotypes showed leaf chlorosis and developed both lenticels and adventitious roots. Biomass production and metal accumulation in tissues varied with Salix genotypes. The flooded genotypes dramatically decreased aerial biomass production compared with corresponding non-flooded genotypes. All the control Salix genotypes showed relatively high accumulation for Cd, Zn and Cu in aerial parts due to high EDTA-extractable metals in the rhizosphere, exhibiting phytoextraction features. In contrast, the flooded genotypes drastically decreased uptake, translocation, accumulation, and extraction capacities for Cd, Zn and Cu in aerial parts, differing with genotypes, and tended to phyto-stabilize them in roots, especially Cu. This study indicated that flooding is a leading factor on phytoremediation efficiency for contaminated sites with willows.

Soil trace elements (TEs) contamination has become a worldwide problem in arable lands and poses great risk to human health via food chain. Intercropping of hyperaccumulator and cash crops is now proposed as a promising alternative phytoremediation technique to address the issue. However, the effect of intercropping in different soil types and field-scale benefits evaluation are rarely reported. A greenhouse pot experiment and a field trial were therefore designed to explore the effects of intercropping Sedum alfredii (hyperaccumulative population) and oilseed rape on Cd phytoextraction potential, Cd transport and crop production, as well as establishing a feasible assessment framework on the basis of benefits evaluation in contaminated soils. Compared with oilseed rape monoculture, intercropping with S. alfredii significantly and consistently increased biomass, seed yield and Cd accumulation in oilseed rape in five typical soil types. Accumulations of Cd varied with soil types, ranging from 22.8 to 4000 μg pot−1. Stepwise multiple linear regression analysis (SMLRA) showed Cd concentrations in plants were related to available phosphorus (AP), pH, soil organic matter (OM), available potassium (AK), silt and sand; R2 values varied from 0.834 to 0.994 (P

The emergence of the COVID-19 pandemic has led to significant public health crisis all over the world. The rapid spreading nature and high mortality rate of COVID-19 places a huge pressure on scientists to develop effective diagnostics and therapeutics to control the pandemic. Some scientists working on plant biotechnology together with commercial enterprises for the emergency manufacturing of diagnostics and therapeutics have aimed to fulfill the rapid demand for SARS-CoV-2 protein antigen and antibody through a rapid, scalable technology known as transient/stable expression in plants. Plant biotechnology using transient/stable expression offers a rapid solution to address this crisis through the production of low-cost diagnostics, antiviral drugs, immunotherapy, and vaccines. Transient/stable expression technology for manufacturing plant-based biopharmaceuticals is already established at commercial scale. Here, current opinions regarding how plant biotechnology can help fight against COVID-19 through the production of low-cost diagnostics and therapeutics are discussed.