Publications by authors named "Xingmei Liu"

79 Publications

Alkaline lignin does not immobilize cadmium in soils but decreases cadmium accumulation in the edible part of lettuce (Lactuca sativa L.).

Environ Pollut 2022 Aug 2:119879. Epub 2022 Aug 2.

Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou, 310058, China. Electronic address:

Heavy metal contamination and low use efficiency of phosphorus (P) fertilizers are worldwide issues. Alkaline lignin is expected to decrease the heavy metal risk and enhance the P availability in heavy-metal-contaminated soils. A 120-day incubation study examined the effects of alkaline lignin on Cd, Pb and P bioavailability and transformation in Cd or Cd/Pb co-contaminated red and cinnamon soils and elucidated the associated mechanisms. A pot experiment further tested Cd accumulation in lettuce (Lactuca sativa L.) grown in the Cd-contaminated red soil. The amendment of alkaline lignin increased the concentrations of bioavailable Cd by 13-20% in the acid red soil and 97-107% in the alkaline cinnamon soil, respectively, being due to the increase of dissolved organic C concentrations. Meanwhile, it also increased the concentrations of available P in both soils, Al-P in red soil and Ca-P in cinnamon soil. Consequently, alkaline lignin amendment increased lettuce biomass by 8-23% in shoots and by 56-71% in roots, P uptake by 37-50% in shoots and by 28-62% in roots, and limited Cd transport from root to shoot which decreased Cd concentrations by 26% in lettuce shoot (edible part). The results suggest that alkaline lignin increases plant growth and decreases Cd bioaccumulation in the shoot through restricting Cd translocation from the root to shoot and increasing soil P availability but not Cd immobilization, and hence may have potential to reduce vegetable Cd contamination risk.
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http://dx.doi.org/10.1016/j.envpol.2022.119879DOI Listing
August 2022

Vibrio cholerae senses human enteric α-defensin 5 through a CarSR two-component system to promote bacterial pathogenicity.

Commun Biol 2022 06 8;5(1):559. Epub 2022 Jun 8.

The Second Clinical Medical College, Jinan University, The First Affiliated Hospital, Southern University of Science and Technology, Shenzhen People's Hospital, Shenzhen Institute of Respiratory Diseases, Shenzhen, Guangdong, PR China.

Vibrio cholerae (V. cholerae) is an aquatic bacterium responsible for acute and fatal cholera outbreaks worldwide. When V. cholerae is ingested, the bacteria colonize the epithelium of the small intestine and stimulate the Paneth cells to produce large amounts of cationic antimicrobial peptides (CAMPs). Human defensin 5 (HD-5) is the most abundant CAMPs in the small intestine. However, the role of the V. cholerae response to HD-5 remains unclear. Here we show that HD-5 significantly upregulates virulence gene expression. Moreover, a two-component system, CarSR (or RstAB), is essential for V. cholerae virulence gene expression in the presence of HD-5. Finally, phosphorylated CarR can directly bind to the promoter region of TcpP, activating transcription of tcpP, which in turn activates downstream virulence genes to promote V. cholerae colonization. In conclusion, this study reveals a virulence-regulating pathway, in which the CarSR two-component regulatory system senses HD-5 to activate virulence genes expression in V. cholerae.
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http://dx.doi.org/10.1038/s42003-022-03525-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9178039PMC
June 2022

Novel insights into probabilistic health risk and source apportionment based on bioaccessible potentially toxic elements around an abandoned e-waste dismantling site.

Sci Total Environ 2022 Sep 30;838(Pt 3):156372. Epub 2022 May 30.

College of Environmental and Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou 310058, China. Electronic address:

The study of potentially toxic element (PTE) hazards around e-waste recycling areas has attracted increasing attention but does not consider elemental bioaccessibility. Here, the respiratory and oral bioaccessibilities were incorporated into probabilistic health risk evaluation and source contribution apportionment. The results showed that soil Cd yielded the highest respiratory and oral bioaccessibility, whereas Cr in soils and vegetables attained the lowest oral bioaccessibility. When incorporating metal bioaccessibility into health risk assessment, a 48.3%-55.7% overestimation of non-cancer and cancer risks can be avoided relative to the risk assessment based on the total concentrations of PTEs. More importantly, priority control metals were misidentified without consideration of bioaccessibility. Cadmium, As, and Cr were screened as the priority metal(loid)s for targeted risk control based on the total PTEs, whereas Cd, Zn, and Cu were the priority metal(loid)s based on the bioaccessible PTEs. Furthermore, source apportionment revealed that >50% of oral bioaccessible Cd, Cu, Ni, Pb, and Zn in farmland were contributed by e-waste dismantling activities, whereas bioaccessible As and Cr mainly originated from agrochemical applications and natural sources, respectively. This study emphasizes the refinement of risk estimation and source apportionment through metal bioaccessibility adjustment, which facilitates the realistic assessment of adverse health effects in humans and the precise identification of high-risk sources.
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http://dx.doi.org/10.1016/j.scitotenv.2022.156372DOI Listing
September 2022

SmSrCoNiO-A Novel Bifunctional Electrocatalyst for Oxygen Reduction/Evolution Reactions.

Molecules 2022 Feb 14;27(4). Epub 2022 Feb 14.

Heilongjiang Provincial Key Laboratory of Polymeric Composite Materials, College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006, China.

The development of non-precious metal catalysts with excellent bifunctional activities is significant for air-metal batteries. ABO-type perovskite oxides can improve their catalytic activity and electronic conductivity by doping transition metal elements at B sites. Here, we develop a novel SmSrCoNiO (SSCN) nanofiber-structured electrocatalyst. In 0.1 M KOH electrolyte solution, SmSrCoNiO (SSCN82) with the optimal Co: Ni molar ratio exhibits good electrocatalytic activity for OER/ORR, affording a low onset potential of 1.39 V, a slight Tafel slope of 123.8 mV dec, and a current density of 6.01 mA cm at 1.8 V, and the ORR reaction process was four-electron reaction pathway. Combining the morphological characteristic of SSCN nanofibers with the synergistic effect of cobalt and nickel with a suitable molar ratio is beneficial to improving the catalytic activity of SSCN perovskite oxides. SSCN82 exhibits good bi-functional catalytic performance and electrochemical double-layer capacitance.
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http://dx.doi.org/10.3390/molecules27041263DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8877539PMC
February 2022

Biochar-supported nanoscale zero-valent iron can simultaneously decrease cadmium and arsenic uptake by rice grains in co-contaminated soil.

Sci Total Environ 2022 Mar 3;814:152798. Epub 2022 Jan 3.

Institute of Soil and Water Resources and Environmental Science, College of Environmental & Resource Sciences, Zhejiang University, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Hangzhou 310058, China. Electronic address:

Cadmium (Cd) and Arsenic (As) in rice grains are a primary exposure source for human beings. However, the simultaneous stabilization of Cd and As in soil becomes difficult due to the opposite properties of those. In this study, we investigated the simultaneous effects of biochar-supported nanoscale zero-valent iron (nZVI-BC) and water management on the decrease of Cd and As bioaccumulation in rice grain. Compared to the control, 0.25-1.00% nZVI-BC coupled with alternate wetting and drying (AWD) management simultaneously decreased the bioaccumulation of Cd and As in rice grains by 15.85-69.16% and 23.06-59.45%, respectively. The cancer risk associated with rice consumption effectively reduced by 15.60-52.41% after the application of nZVI-BC, and the lowest cancer risk was detected in 1.00% nZVI-BC under AWD management. Furthermore, rice cultivated under AWD management had a lower total cancer risk than that cultivated under continuous flooded (CF) management with the same amendment of type and dose. The reduction of soil Cd and As availability and the formation of iron plaque dominated the decrease of Cd and As uptake by rice grains. The elevated soil pH was responsible for Cd adsorption, and the dominant mechanism for As immobilization was the formation of complexes. The iron plaque was double-edged, promoting and inhibiting Cd uptake by rice, wherein the inhibition was predominant under aerobic conditions. In addition, iron plaque was a barrier to preventing the As accumulation by rice, a larger amount of As was immobilized on the iron plaque with nZVI-BC treatment. This study sheds new insights on the simultaneous remediation of Cd and As co-contaminated paddy fields.
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http://dx.doi.org/10.1016/j.scitotenv.2021.152798DOI Listing
March 2022

Potential driving forces and probabilistic health risks of heavy metal accumulation in the soils from an e-waste area, southeast China.

Chemosphere 2022 Feb 6;289:133182. Epub 2021 Dec 6.

College of Environmental Natural Resource Sciences, Zhejiang University, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Hangzhou, 310058, China. Electronic address:

The integrated analysis of the distribution characteristics, health risks, and source identification of heavy metals is crucial for formulating prevention and control strategies for soil contamination. In this study, the area around an abandoned electronic waste dismantling center in China was selected as the research area. The probabilistic health risks caused by heavy metals were evaluated by the Monte Carlo simulation. Random forest, partial least squares regression, and generalized linear models were utilized to predict heavy metal distributions and identify the potential driving factors affecting heavy metal accumulation in soil. The relationships of spatial variation between the heavy metal contents and environmental variables were further visualized. The results revealed that cadmium (Cd) and copper (Cu) were the primary soil pollutants in the study area and caused high ecological risks. The probabilistic health risk assessment indicated that the non-carcinogenic and carcinogenic risks for all populations were acceptable. However, children are more susceptible to heavy metal soil contamination than adults. The sensitivity analyses indicated that the total contents of soil heavy metals and soil ingestion rate were the dominant factors affecting human health. The random forest model, with R values of 0.41, 0.65, 0.57, 0.71, and 0.58 for Cd, Cu, Ni, Zn, and Pb, respectively, predicted the heavy metal concentrations better than the other two models. The distance to the nearest industrial enterprise, industrial output, and agricultural chemical input were the main factors affecting Cd, Cu, Zn, and Pb accumulations in the soil, and soil pH and soil parent material were the primary factors influencing Ni accumulation in the soil. The visualization results of the geographically weighted regression model showed a significant relationship between soil heavy metal contents and industrial activity level. This study could be utilized as a reference for policymakers to formulate prevention and control strategies for heavy metal pollution in agricultural areas.
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http://dx.doi.org/10.1016/j.chemosphere.2021.133182DOI Listing
February 2022

Performance of biochar-supported nanoscale zero-valent iron for cadmium and arsenic co-contaminated soil remediation: Insights on availability, bioaccumulation and health risk.

Environ Pollut 2021 Dec 25;290:118054. Epub 2021 Aug 25.

College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Hangzhou, 310058, China. Electronic address:

Simultaneous stabilization of cadmium (Cd) and arsenic (As) in co-contaminated soil is challenging in environmental remediation because of their opposite properties. In this study, biochar-supported nanoscale zero-valent iron (nZVI-BC) was designed for simultaneously decreasing the soil availability of Cd and As and their bioaccumulation in vegetables. It was found that nZVI-BC exhibited remarkable performance for the stabilization of Cd and As in soil, and their availability decreased by 34.93% and 32.64% compared to the control sample, respectively, under 1.00% nZVI-BC treatment. The increase of soil pH and complexation dominated the Cd remediation process, while the formation of precipitation together and surface complexes transformed labile As into stable forms. Pot experiments showed that nZVI-BC application inhibited the bioaccumulation of Cd and As in vegetables by 23.63-36.48% and 43.09-45.10%, respectively, and hence effectively decreased the cancer risks by 38.19-42.93% related with vegetable consumption (P < 0.05). This study revealed that nZVI-BC is a promising amendment for achieving the simultaneous remediation of Cd and As co-contaminated farmland soil.
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http://dx.doi.org/10.1016/j.envpol.2021.118054DOI Listing
December 2021

Novel agricultural waste-based materials decrease the uptake and accumulation of cadmium by rice (Oryza sativa L.) in contaminated paddy soils.

Environ Pollut 2021 Nov 26;289:117838. Epub 2021 Jul 26.

Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China. Electronic address:

Heavy metal pollution in paddy fields has caused widespread concerns due to the threat to food safety. The present study used low-cost sugarcane bagasse (SB) and two sugarcane bagasse materials modified with citric-acid (SSB) and citric-acid/FeO (MSB) to investigate their effects on the bioavailability of Cd in soil and Cd accumulations in rice in a pot experiment. The three organic amendments significantly decreased the Cd accumulation in plants by limiting its mobilization in soil. The MSB and SSB but not SB increased the soil pH and immobilized the Cd in soil significantly during the 120-day experiment. The amendments decreased Cd bioavailability through transforming to the stable fraction throughout the whole growth stage. The functional groups in the amendments (-OH, -COOH, C-O, -COO and Fe-O) and precipitates [Cd(NO)K(NO), Cd(OH) and CdZnFeO] played active roles in Cd immobilization. Moreover, the three organic materials increased the content of Fe-Mn plaque on rice roots, which prevented its transport from soil to rice roots further. We also found that Fe competed with Cd for transporters and reduced potential Cd uptake and translocation in rice tissues. The addition of MSB and SB but not SSB inhibited the rice growth compared to the unamended control, indicating the potential of SSB in situ remediation. These results provide valuable information to use organic amendments for Cd passivation in soil and food safety.
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http://dx.doi.org/10.1016/j.envpol.2021.117838DOI Listing
November 2021

A fructose/H symporter controlled by a LacI-type regulator promotes survival of pandemic Vibrio cholerae in seawater.

Nat Commun 2021 07 30;12(1):4649. Epub 2021 Jul 30.

The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, P. R. China.

The bacterium Vibrio cholerae can colonize the human intestine and cause cholera, but spends much of its life cycle in seawater. The pathogen must adapt to substantial environmental changes when moving between seawater and the human intestine, including different availability of carbon sources such as fructose. Here, we use in vitro experiments as well as mouse intestinal colonization assays to study the mechanisms used by pandemic V. cholerae to adapt to these environmental changes. We show that a LacI-type regulator (FruI) and a fructose/H symporter (FruT) are important for fructose uptake at low fructose concentrations, as those found in seawater. FruT is downregulated by FruI, which is upregulated when O concentrations are low (as in the intestine) by ArcAB, a two-component system known to respond to changes in oxygen levels. As a result, the bacteria predominantly use FruT for fructose uptake under seawater conditions (low fructose, high O), and use a known fructose phosphotransferase system (PTS, Fpr) for fructose uptake under conditions found in the intestine. PTS activity leads to reduced levels of intracellular cAMP, which in turn upregulate virulence genes. Our results indicate that the FruT/FruI system may be important for survival of pandemic V. cholerae in seawater.
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http://dx.doi.org/10.1038/s41467-021-24971-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8324912PMC
July 2021

Effect of alkaline lignin on immobilization of cadmium and lead in soils and the associated mechanisms.

Chemosphere 2021 Oct 24;281:130969. Epub 2021 May 24.

Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou, 310058, China. Electronic address:

Lignin is a low-cost and environmental-friendly material and could increase the solubility of phosphorus (P) in soils. Meanwhile, application of P compounds to soils decreases the bioavailability of heavy metals. However, there are few reports on whether lignin-induced P release immobilizes heavy metals in soil. This study investigated this possibility by adding alkaline lignin to forest, paddy and upland soils differing in pH and available P. The amendment of alkaline lignin increased soil P availability and enhanced the adsorption and decreased the desorption percentages of Cd in acid forest and paddy soils. The P released from the soil could immobilize Pb and Cd but the presence of Pb decreased the adsorption capacity of Cd on the acid soils. In comparison, the alkaline lignin decreased Cd adsorption and raised Cd desorption in the alkaline upland soil, due to the formation of soluble complex of hydrophilic organic matter with Cd. In addition, precipitation, complexion, and competition effect among Cd, P and lignin in different soils led to various P concentrations in the experiment. The study suggests that alkaline lignin was effective in Cd/Pb immobilization partly via enhanced P availability in acid soils, but was ineffective in Cd immobilization in alkaline soils.
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http://dx.doi.org/10.1016/j.chemosphere.2021.130969DOI Listing
October 2021

A synthesis framework using machine learning and spatial bivariate analysis to identify drivers and hotspots of heavy metal pollution of agricultural soils.

Environ Pollut 2021 Oct 17;287:117611. Epub 2021 Jun 17.

College of Environmental & Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou, 310058, China.

Source apportionment can be an effective tool in mitigating soil pollution but its efficacy is often limited by a lack of information on the factors that influence the accumulation of pollutants at a site. In response to this limitation and focusing on a suite of heavy metals identified as priorities for pollution control, the study established a comprehensive pollution control framework using factor identification coupled with spatial agglomeration for agricultural soils in an industrialized part of Zhejiang Province, China. In addition to elucidating the key role of industrial and traffic activities on heavy metal accumulation through implementing a receptor model, specific influencing factors were identified using a random forest model. The distance from the soil sample location to the nearest likely industrial source was the most important factor in determining cadmium and copper concentrations, while distance to the nearest road was more important for lead and zinc pollution. Soil parent materials, pH, organic matter, and clay particle size were the key factors influencing accumulation of arsenic, chromium, and nickel. Spatial auto-correlation between levels of soil metal pollution and industrial agglomeration can enable a more targeted approach to pollution control measures. Overall, the approach and results provide a basis for improved accuracy in source apportionment, and thus improved soil pollution control, at the regional scale.
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http://dx.doi.org/10.1016/j.envpol.2021.117611DOI Listing
October 2021

Co-benefits of biochar-supported nanoscale zero-valent iron in simultaneously stabilizing soil heavy metals and reducing their bioaccessibility.

J Hazard Mater 2021 09 6;418:126292. Epub 2021 Jun 6.

College of Environmental & Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou 310058, China. Electronic address:

We investigated the performance and encapsulation mechanisms of novel biochar-supported nanoscale zero-valent iron (nZVI-BC) used for the remediation of soil co-contaminated with arsenic (As), cadmium (Cd), and lead (Pb) via incubation and column experiments. Compared with the control, 0.50% of nZVI-BC significantly decreased the leakage of As, Cd, and Pb by 97.94-98.45%, 42.86-81.12%, and 82.14-92.49%, respectively. In addition, 0.50% of nZVI-BC could transform the fraction of unstable heavy metals into a stable form, which substantially decreased the availability, leachability, and bioaccessibility of the heavy metals and hence greatly reduced the human health exposure risk. Column experiments showed that 0.50% of nZVI-BC effectively restrained the leaching of As, Cd, and Pb by 95.60-99.84%, 70.82-84.18%, and 91.68-99.81%, respectively. The predominant encapsulation mechanisms of nZVI-BC included complexation, precipitation/co-precipitation, reduction, and the formation of ternary surface complexes. Based on these insights, we can devise new strategies for the remediation of soil co-contaminated with As, Cd, and Pb.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126292DOI Listing
September 2021

Heavy metals in soil-vegetable system around E-waste site and the health risk assessment.

Sci Total Environ 2021 Jul 15;779:146438. Epub 2021 Mar 15.

College of Environmental and Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou 310058, China.

Investigating the farmland quality around electronic waste (E-waste) dismantling site and taking positive measures to ensure local food safety are urgent. Eleven types of vegetables (n = 184) and their corresponding soils were collected from vegetable fields in a city with famous historical e-waste activities in China. Nemerow integrated pollution indices analysis revealed that local vegetable fields suffered from heavy metal pollution to a certain extent, especially with regards to Cd, Cu, and Zn. The human health risk models provided by USEPA have been used to evaluate the non-carcinogenic and carcinogenic risks associated with the consumption of vegetables by local residents. Results indicated that both adults and children were suffering potential health risks. And the consumption of lettuce and sweet potato caused the greatest health risk, whereas cabbage and cowpea were relatively safe. The bioaccumulation factors (BAF) of heavy metals in various vegetables were calculated, and different vegetables showed huge variance in metal accumulation. Considering both contamination status and health risk assessment, cabbage and cowpea were selected as low accumulators of heavy metals. This study reveals the need for adjusting plantation structure and applying amendments to current protocols to alleviate the adverse effects caused by soil pollution.
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http://dx.doi.org/10.1016/j.scitotenv.2021.146438DOI Listing
July 2021

Effects of magnetic biochar-microbe composite on Cd remediation and microbial responses in paddy soil.

J Hazard Mater 2021 07 24;414:125494. Epub 2021 Feb 24.

College of Environmental Natural Resource Sciences, Zhejiang University, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Hangzhou 310058, China. Electronic address:

There is growing global interest in the bioremediation of cadmium (Cd) using combinations of biochar and microorganisms. However, the interactions among biochar, introduced and indigenous microorganisms remain unclear. Accordingly, a 90 day microcosm experiment was conducted to investigate this by adding Bacillus sp. K1 strain inoculated rice straw biochar (SBB) and magnetic straw biochar (MBB) into a Cd contaminated paddy soil from Hunan, China. All treatments were incubated aerobically (60% water holding capacity) or anaerobically for 90 d. During both soil incubations, Bacillus sp. K1 successfully colonized in soil with composites applications. Soil pH was significantly increased from acid to neutral, and available Cd decreased with the addition of both composites. The better remediation efficiency of MBB than SBB under anerobic conditions was attributed to the transformation of acetic acid-extractable Cd into the residual fraction, caused by Cd bonding with crystal FeO. The application of the two kinds of composites caused similar changes to both microbial communities. There was a slight decrease in indigenous microbial alpha diversity with the MBB aerobic application, while the total population number of bacteria was increased by 700%. Both the redundancy analysis and Mantel analyses indicated that pH and microbial biomass C contributed to the colonization of Bacillus sp. K1 with SBB under aerobic conditions, and with MBB under anerobic conditions, respectively. The research provides a new insight into interactive effects and investigates immobilization mechanisms involved of bacterial/biochar composites in anaerobic and aerobic soils.
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http://dx.doi.org/10.1016/j.jhazmat.2021.125494DOI Listing
July 2021

Warming facilitates microbial reduction and release of arsenic in flooded paddy soil and arsenic accumulation in rice grains.

J Hazard Mater 2021 04 20;408:124913. Epub 2020 Dec 20.

Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou 310058, China.

Global warming severely hinders both rice (Oryza sativa L.) quality and yield by increasing arsenic (As) bioavailability in paddy soils. However, details regarding As biotransformation and migration in the rice-soil system at elevated temperatures remain unclear. This study investigated the effects of increasing temperature on As behavior and translocation in rice grown in As-contaminated paddy soil at two temperature treatments (33 °C warmer temperature and 28 °C as control). The results showed that increasing temperature from 28 °C to 33 °C significantly favored total As, arsenite (As(III)) and arsenate (As(Ⅴ)) release into the soil pore-water. This increase in As bioavailability resulted in significantly higher As(III) accumulation in the whole grains at warmer treatment relative to the control. Moreover, the results suggest that increasing temperature to 33 °C promoted As(III) migration from the roots to the whole grains. Furthermore, the As(V)-reducing Xanthomonadales order and Alcaligenaceae family, and As(V) reductase-encoding arsC gene were enriched in the rhizosphere soils incubated at 33 °C. This suggests that the increase in As bioavailability in that treatment was due to enhanced As(V) reductive dissolution into the soil pore-water. Overall, this study provides new insights on how warmer future temperatures will exacerbate As accumulation in rice grains.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124913DOI Listing
April 2021

Attapulgite and processed oyster shell powder effectively reduce cadmium accumulation in grains of rice growing in a contaminated acidic paddy field.

Ecotoxicol Environ Saf 2021 Feb 28;209:111840. Epub 2020 Dec 28.

Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou 310058, China. Electronic address:

Heavy-metal contamination is widespread in agricultural soils worldwide, especially paddy soils contaminated by Cd. Amendment-induced immobilization of heavy metals is an attractive and effective technique, provided that cost-effective materials are used. This field experiment compared three alkaline passivators (attapulgite, processed oyster shell powder, and mixed soil conditioner) at a rate of 2.25 t ha for their effectiveness in decreasing Cd bioavailability in soils and accumulation in rice plants in a paddy field contaminated by Cd (0.38 Cd mg kg). The utilization of attapulgite and processed oyster shell powder decreased labile fractions but increased stable fractions of Cd in soils through ion exchange, precipitation and complexation. The addition of attapulgite decreased the concentration of bioavailable Cd in both bulk and rhizosphere soils, whereas the amendment of processed oyster shell powder decreased it only in bulk soil. The Cd accumulation in rice plants correlated significantly with acid-soluble and residual Cd fractions in the rhizosphere soil but not in the bulk soil. The addition of attapulgite and processed oyster shell powder decreased Cd accumulation in rice grains from 0.26 mg kg to 0.14 and 0.19 mg kg, respectively, meeting the National Food Safety Standard (< 0.20 mg kg). However, the mixed soil conditioner did not decrease the Cd accumulation in rice shoots or grains. This study demonstrated that attapulgite and processed oyster shell powder were economic agents in reducing Cd accumulation in rice grains.
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http://dx.doi.org/10.1016/j.ecoenv.2020.111840DOI Listing
February 2021

Changes in microbial community structure due to chronic trace element concentrations in different sizes of soil aggregates.

Environ Pollut 2021 Jan 3;268(Pt B):115933. Epub 2020 Nov 3.

Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou, 310058, PR China. Electronic address:

Studies on the effects of trace elements (TEs) (e.g. Cu, Cd, Zn) on soil microbial communities have provided useful information on the toxicity of TEs to microbes. However, previous studies mainly focused on the effects of TEs on microbial community structure in intact soil, while there are few studies on the impact of TEs on microbial community structure in soil aggregates. In this study, soils previously polluted for 20 years, and now containing low and high TE concentrations derived from, now abandoned, metal smelters were sampled from the surface layer (0-15 cm) of two adjacent Chinese paddy fields. The aim was to determine the effects of TEs on the soil microbial biomass and community structure in different sized soil aggregates. Long-term high TE pollution decreased microbial biomass concentration and species, changed the proportion of bacteria and fungi and decreased the diversity of bacteria in the different sized aggregates. The microbial communities in soil aggregates became clustered with increasing TE concentrations.
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http://dx.doi.org/10.1016/j.envpol.2020.115933DOI Listing
January 2021

Performance and mechanisms for remediation of Cd(II) and As(III) co-contamination by magnetic biochar-microbe biochemical composite: Competition and synergy effects.

Sci Total Environ 2021 Jan 13;750:141672. Epub 2020 Aug 13.

College of Environmental Natural Resource Sciences, Zhejiang University, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Hangzhou 310058, China. Electronic address:

Contaminations by heavy metals in the environment always exist as a mixture of both metal and metalloid. Thus, it is a challenge to simultaneously remove both components due to their adverse chemical behaviors. Herein, effective cadmium (Cd) and arsenic (As) removal in aqueous solution was achieved by use of a novel composite, which was synthesized by Bacillus sp. K1 loaded onto FeO biochar (MBB). The combination with Bacillus sp. K1 provided new biosorption sites such as amine and hydroxyl groups in the composite surface, which significantly increasing the removal capability of Cd(II) by 230% when compared with the raw magnetic biochar. Both competition and synergy effects were found in binary system. Adsorption of As(III) extended active sites for capturing Cd(II), which appeared on the surface of the MBB as type B ternary surface complexes. The maximum adsorption capacity of Cd(II) and As(III) reached 25.04 and 4.58 mg g in a binary system, respectively. In summary, this environmentally friendly composite is promising for simultaneous Cd(II) and As(III) remediation.
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http://dx.doi.org/10.1016/j.scitotenv.2020.141672DOI Listing
January 2021

Policy adjustment impacts Cd, Cu, Ni, Pb and Zn contamination in soils around e-waste area: Concentrations, sources and health risks.

Sci Total Environ 2020 Nov 23;741:140442. Epub 2020 Jun 23.

College of Environmental and Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou 310058, China. Electronic address:

Pollution control policies (PCP) have been implemented in some e-waste dismantling areas in China to curb metal contamination since 2012. We investigated the effects of policy intervention on the concentrations, sources and health risks of heavy metals in soils. Post-implementation, among Cd, Cu, Ni, Pb and Zn, Pb levels declined while the Cd, Cu, Ni and Zn concentrations in soils were not impacted. Changes in their pollution indices and health risks were also similar. After the PCP, the contribution of traffic emission significantly decreased, while natural and industrial contribution increased due to the heighten background input and relocation of small e-waste dismantling workshops. Risk assessment showed that total cancer risk of five metals also slightly increased. Thus, policy intervention might be effective in controlling the release of some metals from e-waste dismantling. However, the performance of control measures varied depending on both source emission and geochemical properties of the metals. This study reveal the ongoing need of stricter supervision, targeted emission reduction and more-effective soil remediation actions to alleviate soil contamination from e-waste dismantling.
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http://dx.doi.org/10.1016/j.scitotenv.2020.140442DOI Listing
November 2020

MicroRNA-27a targets Sfrp1 to induce renal fibrosis in diabetic nephropathy by activating Wnt/β-Catenin signalling.

Biosci Rep 2020 06;40(6)

State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, Guizhou 550025, China.

Diabetic nephropathy (DN) commonly causes end-stage renal disease (ESRD). Increasing evidence indicates that abnormal miRNA expression is tightly associated with chronic kidney disease (CKD). This work aimed to investigate whether miR-27a can promote the occurrence of renal fibrosis in DN by suppressing the expression of secreted frizzled-related protein 1 (Sfrp1) to activate Wnt/β-catenin signalling. Therefore, we assessed the expression levels of miR-27a, Sfrp1, Wnt signalling components, and extracellular matrix (ECM)-related molecules in vitro and in vivo. Sfrp1 was significantly down-regulated in a high-glucose environment, while miR-27a levels were markedly increased. A luciferase reporter assay confirmed that miR-27a down-regulated Sfrp1 by binding to the 3' untranslated region directly. Further, NRK-52E cells under high-glucose conditions underwent transfection with miR-27a mimic or the corresponding negative control, miR-27a inhibitor or the corresponding negative control, si-Sfrp1, or combined miR-27a inhibitor and si-Sfrp1. Immunoblotting and immunofluorescence were performed to assess the relative expression levels of Wnt/β-catenin signalling and ECM components. The mRNA levels of Sfrp1, miR-27a, and ECM-related molecules were also detected by quantitative real-time PCR (qPCR). We found that miR-27a inhibitor inactivated Wnt/β-catenin signalling and reduced ECM deposition. Conversely, Wnt/β-catenin signalling was activated, while ECM deposition was increased after transfection with si-Sfrp1. Interestingly, miR-27a inhibitor attenuated the effects of si-Sfrp1. We concluded that miR-27a down-regulated Sfrp1 and activated Wnt/β-catenin signalling to promote renal fibrosis.
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http://dx.doi.org/10.1042/BSR20192794DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7295625PMC
June 2020

Spatiotemporal modeling of soil heavy metals and early warnings from scenarios-based prediction.

Chemosphere 2020 Sep 29;255:126908. Epub 2020 Apr 29.

College of Environmental and Natural Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou, 310058, China. Electronic address:

Prediction of soil heavy metal concentrations based on continuous site specific investigation can provide reference for soil metal contamination prevention and early warning of soil environmental quality. In this study, the spatiotemporal variations of soil heavy metals (Cd, Ni, Zn, Pb and Cu) in Wenling were analyzed with 132 and 169 soil samples gathered in 2011 and 2016. In addition, we adopted a scenario-simulation model to predict future dynamic concentrations of soil heavy metals under optimistic (the pollution inputs are zero under strict environmental policy) and default (the pollution status maintain constant) conditions. Results indicated that the paddy soil was contaminated mainly by Cd and Cu. Spatiotemporal maps revealed distinct patterns in the joint area, where soil Cd, Ni, Zn, Pb and Cu all increased in northwest. Soil heavy metal concentrations as well as the associated ecological risks would decline gradually under optimistic scenario, while sharply increase when no control acts are taken over long term in default condition. The percentages of soil Cd and Cu that exceeding their corresponding risk screening value (RSV) under the default condition would be 1.6 and 1.3 times higher than those under optimistic scenario 10 years later. The probability of high potential ecological risk in default condition would be twice higher than that under optimistic scenario in 2026. Overall, strengthening the control of pollution sources and strict environmental policy are very important for soil heavy metals contamination prevention and control.
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http://dx.doi.org/10.1016/j.chemosphere.2020.126908DOI Listing
September 2020

Abundance and diversity of microbial arsenic biotransformation genes in the sludge of full-scale anaerobic digesters from a municipal wastewater treatment plant.

Environ Int 2020 05 26;138:105535. Epub 2020 Mar 26.

Institute of Soil and Water Resources and Environmental Science, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.

Arsenic (As) is a potential contaminant in sewage sludge that may affect waste treatment and limit the use of these waste materials as soil amendments. Anaerobic digestion (AD) is an important and effective process for the treatment of sewage sludge and the chemical speciation of As is particularly important in sludge AD. However, the biotransformation genes of As in sludge during AD has not been fully explored. In this study, the influent and effluent sludge of anaerobic digester in a wastewater treatment plant (WWTP) was collected to investigate the species transformations of As, the abundance and diversity of As biotransformation genes was explored by real-time PCR (qPCR) and metagenomic sequencing, separately. The results showed that arsenite [As(III)] and arsenate [As(V)] were predominant in the influent sludge, whereas the relative abundance of monomethylarsenic acid (MMA) increased by 25.7% after digestion. As biotransformation genes were highly abundant, and the As(III) S-adenosylmethionine methyltransferase (arsM) gene was the predominant which significantly increased after AD by qPCR analysis. Metagenomic analysis indicated that the diversity of the arsM-like sequences also increased significantly after AD. Most of the arsM-like sequences in all the influent and effluent sludge samples were related to Bacteroidetes and Alphaproteobacteria. Furthermore, co-occurrence network analysis indicated a strong correlation between the microbial communities and As. This study provides a direct and reliable reference on As biotransformation genes and microbial community in the AD of sludge.
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http://dx.doi.org/10.1016/j.envint.2020.105535DOI Listing
May 2020

A novel calcium-based magnetic biochar reduces the accumulation of As in grains of rice (Oryza sativa L.) in As-contaminated paddy soils.

J Hazard Mater 2020 07 9;394:122507. Epub 2020 Mar 9.

Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China. Electronic address:

The present study used calcium-based magnetic biochar (Ca-MBC), a novel material made through pyrolyzing rice straw impregnated with iron oxide (FeO) and calcium carbonate (CaCO) under oxygen-limited conditions, to reduce arsenic (As) accumulation in rice plants (Oryza sativa L.) through a 130-day pot experiment. The BCR (European Community Bureau of Reference) sequential extraction confirmed that Ca-MBC decreased the unstable fraction of As through transforming to the stable fraction at both tillering stage and maturity. The addition of Ca-MBC decreased while the pristine biochar increased the concentrations of NHHPO- and BCR-extracted As. The μ-XRF test revealed that iron oxide on the Ca-MBC played an important role in decreasing As bioavailability. The addition of Ca-MBC greatly decreased As concentration in rice grains, mainly due to (1) the decreases in bioavailability of As in soil and (2) adsorption of As in pore water by Ca-MBC; and (3) the enhanced formation of iron plaque that acted as a barrier for plant As uptake. Furthermore, the addition of Ca-MBC at 1% but not 2% promoted plant growth. The results suggest that Ca-MBC can be used as an efficient material to lower As accumulation in grains and promote plant growth in rice paddy fields.
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http://dx.doi.org/10.1016/j.jhazmat.2020.122507DOI Listing
July 2020

Association of polymorphisms in the HBG1-HBD intergenic region with HbF levels.

J Clin Lab Anal 2020 Jun 18;34(6):e23243. Epub 2020 Feb 18.

School of Medicine, Guizhou University, Guiyang, China.

Background: Increased levels of fetal hemoglobin (HbF) can improve the clinical course of the patients with sickle cell anemia (SCA) or β-thalassemia. The HBG1-HBD intergenic region plays an important role in this process. However, very few studies investigated whether the variations in this region have an effect on HbF expression.

Methods: We retrieved all the SNP data in the HBG1-HBD intergenic region and defined the haplotype blocks, then performed cluster analysis and selected a tagSNP. A total of 500 normal individuals and 300 β-thalassemia carriers were enrolled. After routine blood and hemoglobin capillary electrophoresis testing, β-thalassemia mutations were detected using PCR-reverse dot blot. The genotypes of the rs4910736 (A > C) and rs10128556 (C > T) were determined using Sanger sequencing; the relationship between the two SNPs and the levels of HbF was analyzed.

Results: Two haplotype blocks were constructed. Block 1 included seven haplotypes divided into two groups M and N by 11 tagSNPs, among which rs4910736 was selected as a tagSNP, while block 2 included three haplotypes. We found that the haplotypes of block 1 were statistically associated with HbF levels, but the non-tagSNP rs10128556 was shown to be more strongly associated with HbF levels than rs4910736.

Conclusion: This work proved that the haplotypes in the HBG1-HBD intergenic region and SNP rs10128556 are both statistically associated with HbF levels, revealing the association of polymorphisms in the HBG1-HBD intergenic region with HbF levels.
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http://dx.doi.org/10.1002/jcla.23243DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7307336PMC
June 2020

Zeolite-supported nanoscale zero-valent iron for immobilization of cadmium, lead, and arsenic in farmland soils: Encapsulation mechanisms and indigenous microbial responses.

Environ Pollut 2020 May 31;260:114098. Epub 2020 Jan 31.

College of Environmental & Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou, 310058, China. Electronic address:

Zeolite-supported nanoscale zero-valent iron (Z-NZVI) has great potential for metal(loid) removal, but its encapsulation mechanisms and ecological risks in real soil systems are not completely clear. We conducted long-term incubation experiments to gain new insights into the interactions between metal(loid)s (Cd, Pb, As) and Z-NZVI in naturally contaminated farmland soils, as well as the alteration of indigenous bacterial communities during soil remediation. With the pH-adjusting and adsorption capacities, 30 g kg Z-NZVI amendment significantly decreased the available metal(loid) concentrations by 10.2-96.8% and transformed them into strongly-bound fractions in acidic and alkaline soils after 180 d. An innovative magnetic separation of Z-NZVI from soils followed by XRD and XPS characterizations revealed that B-type ternary complexation, heterogeneous coprecipitation, and/or concurrent redox reactions of metal(loid)s, especially the formation of Cd(AsO), PbFe(AsO)(OH), and As, occurred only under specific soil conditions. Sequencing of 16S rDNA using Illumina MiSeq platform indicated that temporary shifts in iron-resistant/sensitive, pH-sensitive, denitrifying, and metal-resistant bacteria after Z-NZVI addition were ultimately eliminated because soil characteristics drove the re-establishment of indigenous bacterial community. Meanwhile, Z-NZVI recovered the basic activities of bacterial DNA replication and denitrification functions in soils. These results confirm that Z-NZVI is promising for the long-term remediation of metal(loid)s contaminated farmland soil without significant ecotoxicity.
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http://dx.doi.org/10.1016/j.envpol.2020.114098DOI Listing
May 2020

A novel calcium-based magnetic biochar is effective in stabilization of arsenic and cadmium co-contamination in aerobic soils.

J Hazard Mater 2020 04 2;387:122010. Epub 2020 Jan 2.

Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China. Electronic address:

This study developed a novel calcium-based magnetic biochar by pyrolysing rice straw mixed with calcium carbonate and iron oxide for stabilization of contamination of multiple metals. A 160-day incubation study was conducted to investigate its performance in stabilization of cadmium and arsenic co-contamination in soil. Both biochar and Ca-MBC treatments increased soil pH, decreased the bioavailability of cadmium. Ca-MBC decreased but biochar enhanced the bioavailability of arsenic. The BCR (European Community Bureau of Reference) sequential extraction confirmed Ca-MBC facilitated the transformation of the unstable fraction of arsenic to stable fractions. The stabilization mechanisms were explored through synchrotron-based micro X-ray fluorescence and X-ray absorption near edge structure. The results show that Ca-MBC remediated the dual contamination of arsenic and cadmium through (1) elevated pH and cation exchange capacity (for Cd); (2) the formation of bi-dentate chelate and ternary surface complexes on the surface of iron oxide; (3) enhanced adsorption ability of porous biochar. In addition, Ca-MBC increased the abundance and diversity of bacterial community, and modified the relative abundances of bacterial taxa, leading to a shift of the composition. These new insights provide valuable information for stabilization of co-contamination of arsenic and cadmium in soil using the potential material Ca-MBC.
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http://dx.doi.org/10.1016/j.jhazmat.2019.122010DOI Listing
April 2020

Simultaneous immobilization of the cadmium, lead and arsenic in paddy soils amended with titanium gypsum.

Environ Pollut 2020 Mar 10;258:113790. Epub 2019 Dec 10.

Institute of Soil and Water Resources and Environmental Science, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.

In situ immobilization of heavy metals in contaminated soils using industrial by-products is an attractive remediation technique. In this work, titanium gypsum (TG) was applied at two levels (TG-L: 0.15% and TG-H: 0.30%) to simultaneously reduce the uptake of cadmium (Cd), lead (Pb) and arsenic (As) in rice grown in heavy metal contaminated paddy soils. The results showed that the addition of TG significantly decreased the pH and dissolved organic carbon (DOC) in the bulk soil. TG addition significantly improved the rice plants growth and reduced the bioavailability of Cd, Pb and As. Particularly, bioavailable Cd, Pb and As decreased by 35.2%, 38.1% and 38.0% in TG-H treatment during the tillering stage, respectively. Moreover, TG application significantly reduced the accumulation of Cd, Pb and As in brown rice. Real-time PCR analysis demonstrated that the relative abundance of sulfate-reducing bacteria increased with the TG application, but not for the iron-reducing bacteria. In addition, 16S rRNA sequencing analysis revealed that the relative abundances of heavy metal-resistant bacteria such as Bacillus, Sulfuritalea, Clostridium, Sulfuricella, Geobacter, Nocardioides and Sulfuricurvum at the genus level significantly increased with the TG addition. In conclusion, the present study implied that TG is a potential and effective amendment to immobilize metal(loid)s in soil and thereby reduce the exposure risk of metal(loid)s associated with rice consumption.
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http://dx.doi.org/10.1016/j.envpol.2019.113790DOI Listing
March 2020

Achieving the safe use of Cd- and As-contaminated agricultural land with an Fe-based biochar: A field study.

Sci Total Environ 2020 Mar 5;706:135898. Epub 2019 Dec 5.

Institute of Soil and Water Resources and Environmental Science, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.

A field study was conducted to investigate the effect of Fe-based biochar application on the extractability and availability of Cd and As, as well as its impact on crop growth and yield under a two-years wheat-rice rotation system. The Fe-based biochar was applied to the soil at 1.5 and 3.0 t ha, manure compost was also applied as a comparison, as well as a non-treated control. The application of the Fe-based biochar significantly (p < 0.05) increased the crop yields for the rice season in the first year, but the both treatments had no significant effect on the crop yields in the others cultivation seasons, compared to the control. The concentrations of available Cd and As significantly (p < 0.05) decreased after either higher or lower dose of Fe-based biochar addition, especially with lower rate in the second year. In the second year, the soil extractable Cd and As reduced by 57% and 18%, respectively, in the wheat season and 63% and 14%, respectively, in the rice season, after the lower dose of Fe-based biochar was applied. The lower dose of the Fe-based biochar treatment showed higher efficiency for decreasing Cd and As availability in soil than the higher one, the control and manure compost treatment. Additionally, both the higher and lower doses of the Fe-based biochar treatments significantly decreased Cd and As uptake by wheat and rice plants. Overall, the Fe-based biochar showed effective immobilization at an application of 1.5 t ha, making the use of the Fe-based biochar feasible as an amendment for the safe use of agricultural land contaminated by Cd and As.
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http://dx.doi.org/10.1016/j.scitotenv.2019.135898DOI Listing
March 2020

Simultaneous adsorption of Cd(II)andAs(III)by a novel biochar-supported nanoscale zero-valent iron in aqueous systems.

Sci Total Environ 2020 Mar 31;708:134823. Epub 2019 Oct 31.

College of Environmental & Resource Sciences of Zhejiang University, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Hangzhou 310058, China.

Biochar-supported nanoscale zero-valent iron (nZVI-BC) is a promising material for Cd(II) and As(III) removal from aqueous systems. In this study, simplified nZVI-BC composites were successfully synthesized and characterized via scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectrometry (XPS), and Fourier transform infrared spectroscopy (FTIR) to understand the underlying adsorption mechanism. SEM and FTIR confirmed that nZVI particles were distributed evenly on the biochar surface. XRD and XPS revealed that metal ions were separated from solutions via electrostatic adsorption, complexation, oxidation, precipitation/co-precipitation, and the formation of type B ternary surface complex. Batch experiments showed that nZVI-BC (1:1) had a high removal efficiency in a wide pH range of 5.0-8.0 for Cd(II) and 3.0-8.0 for As(III), the maximum Cd(II) and As(III) adsorption capacities were 33.81 and 148.5 mg/g within 2 and 1 h, respectively. Additionally, synergisticeffects considerably enhanced the adsorption capacity of nZVI-BC(1:1) in mixed adsorption systems, the adsorption capacities of Cd(II) and As(III) reached 179.9 and 158.5 mg/g, respectively. Hence, nZVI-BC(1:1) is an ideal candidate for Cd(II) and As(III) pollution treatment.
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http://dx.doi.org/10.1016/j.scitotenv.2019.134823DOI Listing
March 2020

Reduced Cd, Pb, and As accumulation in rice (Oryza sativa L.) by a combined amendment of calcium sulfate and ferric oxide.

Environ Sci Pollut Res Int 2020 Jan 20;27(2):1348-1358. Epub 2019 Nov 20.

Institute of Soil and Water Resources and Environmental Science, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China.

A combined amendment (CF) consisting of 90% calcium sulfate (CaSO) and 10% ferric oxide (FeO) was used to investigate the feasibility, active principles, and possible mechanisms of the immobilization of heavy metals in paddy soil. A soil incubation experiment, two consecutive pot trials, and a field experiment were conducted to evaluate the effectiveness and persistence of CF on metal(loid) immobilization. Soil incubation experiment results indicated that the application of CF significantly decreased the concentrations of cadmium (Cd), lead (Pb), and arsenic (As) in soil solution. CF treatments simultaneously reduced the accumulation of Cd, Pb, and As in two consecutive pot trials. The total Cd, Pb, and As concentrations in the rice grains were respectively 0.02, 2.08, and 0.62 mg kg in the control treatment in the second year, which exceeded the safety limits of contaminants in food products in China. However, a high amount of CF amendment (CF-H, 0.3%) effectively decreased Cd, Pb, and As by 75.0%, 75.5%, and 46.8%, respectively. Further, with the CF amendment, the bioavailable Cd and Pb in the soil and the accumulation of Cd, Pb, and As in rice grain in the field experiment were also significantly decreased. The concentrations of Cd, Pb, and As in grains were respectively 0.02, 0.03, and 0.39 mg kg in the control treatment in the field experiment, which decreased to 0.01, 0.01, and 0.22 mg kg with CF addition, suggesting that grains produced in the field could pose less health risk. In conclusion, these results implied that CF was an effective and persistent combined amendment to immobilize heavy metals in soil and thereby can reduce the exposure risk of metal(loid)s associated with rice consumption.
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http://dx.doi.org/10.1007/s11356-019-06765-9DOI Listing
January 2020
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