Publications by authors named "Yongguang Yin"

86 Publications

Decreased bioavailability of both inorganic mercury and methylmercury in anaerobic sediments by sorption on iron sulfide nanoparticles.

J Hazard Mater 2021 Sep 30;424(Pt B):127399. Epub 2021 Sep 30.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.

Methylmercury (MeHg), derived via inorganic mercury (Hg(II)) methylation by anaerobic microorganisms, is a neurotoxic contaminant causing concern worldwide. Establishing how to reduce Hg(II) methylation and MeHg bioavailability is essential for effective control of Hg pollution. Iron sulfide nanoparticles (FeS) is a promising passivator for Hg(II) methylation. However, its effect on the fate of MeHg in aquatic systems remains poorly understood. This study investigated the effect of FeS on Hg(II) bioavailability, MeHg production and bioavailability in aquatic environments. Results demonstrated that FeS rapidly sorbed Hg(II) and MeHg, with sorption affected by pH, chloride ion and dissolved organic matter. Hg-specific biosensor analysis showed that Hg(II) sorbed onto FeS significantly reduced its bioavailability to microorganisms. Double stable isotope (Hg(II) and MeHg) addition revealed that FeS significantly inhibited MeHg production in anaerobic sediments. Furthermore, synthetic gut juice extraction suggested that FeS decrease concentrations of bioavailable MeHg and Hg(II), reducing their integration into food webs. However, the sorbed MeHg and Hg(II) in sediments can be released after FeS oxidation, potentially enhancing the risk of exposure to aquatic organisms. Overall, these findings increase our understanding of Hg transformation and exposure risks in aquatic systems, providing valuable information for the development of in situ Hg remediation systems.
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http://dx.doi.org/10.1016/j.jhazmat.2021.127399DOI Listing
September 2021

Dark Reduction of Mercury by Microalgae-Associated Aerobic Bacteria in Marine Environments.

Environ Sci Technol 2021 Oct 29;55(20):14258-14268. Epub 2021 Sep 29.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.

Redox transformation of mercury (Hg) is critical for Hg exchange at the air-sea interface and it can also affect the methylation of Hg in marine environments. However, the contributions of microalgae and aerobic bacteria in oxic seawater to Hg reduction are largely unknown. Here, we studied the reduction of Hg mediated by microalgae and aerobic bacteria in surface marine water and microalgae cultures under dark and sunlight conditions. The comparable reduction rates of Hg with and without light suggest that dark reduction by biological processes is as important as photochemical reduction in the tested surface marine water and microalgae cultures. The contributions of microalgae, associated free-living aerobic bacteria, and extracellular substances to dark reduction were distinguished and quantified in 7 model microalgae cultures, demonstrating that the associated aerobic bacteria are directly involved in dark Hg reduction. The aerobic bacteria in the microalgae cultures were isolated and a rapid dark reduction of Hg followed by a decrease of Hg was observed. The reduction of Hg and re-oxidation of Hg were demonstrated in aerobic bacteria spp. using double isotope tracing (Hg and Hg). These findings highlight the importance of algae-associated aerobic bacteria in Hg transformation in oxic marine water.
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http://dx.doi.org/10.1021/acs.est.1c03608DOI Listing
October 2021

Tracking the dissolution behavior of zinc oxide nanoparticles in skimmed milk powder solutions.

Food Chem 2021 Dec 2;365:130520. Epub 2021 Jul 2.

School of Environment, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, Zhejiang Province, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.

Zinc oxide nanoparticles (ZnO NPs) are recently recommended as food additives owing to their outstanding nutritive function. Therefore, understanding their comprehensive information and stability in food samples is highly necessitated. However, the characterization of ZnO NPs in the complex food matrices remains a great challenge, limiting an in-depth understanding of their transformation during food storage. In this study, the hollow fiber flow field-flow fractionation was combined with UV-Vis absorption spectroscopy and inductively coupled plasma optical emission spectroscopy to assess the dissolution behaviors of ZnO NPs in skimmed milk powder solutions by monitoring the changes in the residual ZnO NPs and the amount of dissolved Zn(II) ions. The simultaneous characterization of these two Zn species in skimmed milk powder solutions was achieved without the need for tedious sample pretreatments, and the dissolution of ZnO NPs in skimmed milk powder solutions had time- and temperature-dependent behaviors.
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http://dx.doi.org/10.1016/j.foodchem.2021.130520DOI Listing
December 2021

[Application of non-stationary phase separation hyphenated with inductively coupled plasma mass spectrometry in the analysis of trace metal-containing nanoparticles in the environment].

Se Pu 2021 Aug;39(8):855-869

Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.

Engineered metal-containing nanoparticles (MCNs), which have unique physical and chemical properties, are widely used in various fields such as medicine, pharmaceuticals, and microelectronics as well as in daily supplies. These MCNs are inevitably released into the environment during production and use, thus posing a threat to bacterial communities, animals, plants, and human health. There are also abundant natural MCNs in the environment, which play an important role in the environmental cycle of metals. The shape, size, and surface properties of MCNs have a significant impact on their migration, chemical and physical transformation, and biological intake in the environment. Therefore, the analysis and detection of MCNs in the environment should be aimed not only at quantifying their concentration and chemical composition, but also at determining their shape, particle size, and surface charge. In addition, for the detection of MCNs in the environment, challenges due to their low concentrations and the interference from complex environmental matrices must be overcome. A single detection technique is often insufficient for the analysis and detection of MCNs in a complex environment matrix. Therefore, the development of an effective and reliable online hyphenated technique is urgently needed for the separation and detection of MCNs in the environment. Such online hyphenated techniques should be able to eliminate the interference by complex matrices, improve the particle size detection range, and reduce the element detection limit. The online hyphenation of stationary phase-based separation techniques such as liquid chromatography and gel electrophoresis with inductively coupled plasma-mass spectrometry (ICP-MS) can effectively separate MCNs according to their particle size, with low element detection limits. However, these stationary phase-based separation techniques have a shortcoming of the adsorption of nanoparticles on the stationary phase, which leads to blockage of separation channels and low recoveries of nanoparticles. The online hyphenation of a non-stationary phase separation technique with ICP-MS also shows strong nanoparticle separation ability and low element detection limits, so that the problem of colloid blockage in stationary phase-based separation can be resolved. This method is very promising for the rapid and accurate characterization of the particle size distribution and chemical composition of MCNs. However, it cannot provide information about the nanoparticle number concentration of MCNs and the elemental content of a single MCN. In complex environmental samples, pure MCNs cannot be effectively distinguished from MCNs with environmental corona having different thicknesses or pure MCNs adsorbed on/hetero-agglomerated with inorganic/organic colloids. Online coupling single-particle ICP-MS (SP-ICP-MS), an emerging particle detection technique with non-stationary phase separation, can effectively help overcome the above shortcomings. This method can provide information on the hydrodynamic diameter, metal mass-derived diameter, total number concentration, size-dependent number, and size-dependent mass concentration of MCNs. Therefore, it enables comprehensive characterization of MCNs based on a variety of three-dimensional contour plot chromatograms. This review summarizes the separation mechanisms and applicable detectors for three commonly used non-stationary phase separation techniques: hydrodynamic chromatography (HDC), capillary electrophoresis (CE), and field-flow fractionation (FFF). In addition, it focuses on the characteristics and applications of online-coupling non-stationary phase separation with ICP-MS and SP-ICP-MS. Regarding FFF, this review focuses on the separation techniques that are suitable for online coupling with ICP-MS, such as sedimentation FFF and flow FFF (symmetrical flow FFF, asymmetrical flow FFF, and hollow fiber flow FFF). In addition, the characteristics of the online hyphenation of three non-stationary phase separations, HDC, CE, and flow FFF, with ICP-MS are compared, including the separation mechanism, sample volume, analytical time, detection sensitivity, size range, size resolution, recovery, reproducibility, and capability for ion analysis. Finally, this review proposes the prospects for future development of the online hyphenation of non-stationary phase separation techniques with ICP-MS and SP-ICP-MS.
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http://dx.doi.org/10.3724/SP.J.1123.2020.12016DOI Listing
August 2021

Aging and phytoavailability of newly introduced and legacy cadmium in paddy soil and their bioaccessibility in rice grain distinguished by enriched isotope tracing.

J Hazard Mater 2021 09 4;417:125998. Epub 2021 May 4.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.

Phytoavailability of Cadmium (Cd) plays a critical role in its accumulation in soil-rice systems. However, differential aging and phytoavailability of newly introduced Cd (Cd) and legacy Cd (Cd) in the soil-rice system remains unknown. Moreover, distinguishing their aging and phytoavailability is challenging. Enriched Cd isotope was introduced into a series of pot experiments, combined with sequential extraction and isotope dilution (Cd isotopic spike), to investigate the aging and distribution of Cd and Cd under different treatments. The treatments included simulated acid rain, slaked lime, and biochar. Cd aged quickly than Cd in flooded soil and its availability was similar to that of Cd after tillering stage. The grain Cd contents were positively correlated to Cd concentrations in the overlying water. Acid rain reduced the soil pH, increasing the grain Cd, while slaked lime reduced grain Cd content. The acidic biochar used in this study increased grain Cd, possibly through soil acidification-induced Cd release. The differences in bioaccumulation and translocation factors between Cd and Cd in rice plants under slaked lime and biochar treatments suggested their different in vivo complexations and translocations. Analysis of bioaccessibility of Cd and Cd in rice grains provided valuable insights regarding human Cd exposure.
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http://dx.doi.org/10.1016/j.jhazmat.2021.125998DOI Listing
September 2021

Katabatic Wind and Sea-Ice Dynamics Drive Isotopic Variations of Total Gaseous Mercury on the Antarctic Coast.

Environ Sci Technol 2021 05 15;55(9):6449-6458. Epub 2021 Apr 15.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.

Clarifying the sources and fates of atmospheric mercury (Hg) in the Antarctic is crucial to understand the global Hg circulation and its impacts on the fragile ecosystem of the Antarctic. Herein, the annual variations in the isotopic compositions of total gaseous Hg (TGM), with 5-22 days of sampling duration for each sample, were presented for the first time to provide isotopic evidence of the sources and environmental processes of gaseous Hg around the Chinese Great Wall Station (GWS) in the western Antarctic. Different from the Arctic tundra and lower latitude areas in the northern hemisphere, positive δHg (0.58 ± 0.21‰, mean ± 1SD) and negative ΔHg (-0.30 ± 0.10‰, mean ± 1SD) in TGM at the GWS indicated little impact from the vegetation-air exchange in the Antarctic. Correlations among TGM ΔHg, air temperature, and ozone concentrations suggested that enhanced katabatic wind that transported inland air masses to the continental margin elevated TGM ΔHg in the austral winter, while the surrounding marine surface emissions controlled by sea-ice dynamics lowered TGM ΔHg in the austral summer. The oxidation of Hg(0) might elevate ΔHg in TGM during atmospheric Hg depletion events but have little impact on the seasonal variations of atmospheric Hg isotopes. The presented atmospheric Hg isotopes were essential to identify the transport and transformation of atmospheric Hg and further understand Hg cycling in the Antarctic.
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http://dx.doi.org/10.1021/acs.est.0c07474DOI Listing
May 2021

Unified Probability Distribution and Dynamics of Lead Contents in Human Erythrocytes Revealed by Single-Cell Analysis.

Environ Sci Technol 2021 03 4;55(6):3819-3826. Epub 2021 Mar 4.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.

Understanding the presence and dynamics of chemical pollutants in individual cells is fundamentally important for their trafficking, fate, and toxicity in humans. The presence of molecular components (i.e., proteins and mRNA) in individual cells of higher organisms is considered a stochastic event. The characteristics of chemical pollutants, as extrinsic compounds, in subpopulation of human cells on single-cell basis have not been explored yet. Here, we demonstrated the lead (Pb) content in individual mature erythrocytes (m-erythrocytes) of Pb-intoxicated patients, and healthy subjects exhibited a unified pattern in probability distribution (gamma distribution) and dynamics, despite being highly heterogeneous. The Pb content in individual m-erythrocytes decreased with the lifetime of m-erythrocytes. Meanwhile, the distribution and dynamics were found to be highly related to the Pb content in m-erythrocytes and was independent of patients and their status. This is the first study to analyze the distribution pattern of chemical pollutants at a single-cell level in higher organisms. This study sheds light on the molecular mechanism of Pb trafficking and fate in humans and the search for an efficient strategy to improve Pb excretion during Pb treatment.
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http://dx.doi.org/10.1021/acs.est.0c05989DOI Listing
March 2021

Fate of mercury and methylmercury in full-scale sludge anaerobic digestion combined with thermal hydrolysis.

J Hazard Mater 2021 03 17;406:124310. Epub 2020 Oct 17.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address:

Methylmercury (MeHg) is one of the highly toxic and bio-accumulated forms of mercury. Its presence in wastewater treatment processes has been evidenced in recent studies. Considering its enrichment in sewage sludge and the ecological risk associated with its land application, this study investigated the fate of mercury and MeHg in full-scale anaerobic digestion combined with Cambi thermal hydrolysis based on one-year sampling. Results showed that the advanced anaerobic digestion could increase the total mercury (THg) content from 4.35 ± 0.43 mg/kg in raw sludge to 6.37 ± 1.05 mg/kg in digested sludge, and the MeHg content decreased from 1.61 to 8.94 ng/g in raw sludge to 0.21-2.03 ng/g after anaerobic digestion. The demethylation of MeHg was dominant in both thermal hydrolysis and anaerobic digestion; it was mostly derived from the physico-chemical impacts such as chemical decomposition in thermal hydrolysis and precipitation in anaerobic digestion. Although the reported microbial methylators, such as Methanosarcina and Clostridia, were dominant in anaerobic digestion, the relative abundances of hgcA and merA were relatively low and did not correlate with the MeHg profiles. Thus, microbial methylation or demethylation seems negligible in terms of MeHg transformation.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124310DOI Listing
March 2021

Selenium(Ⅳ) alleviates chromium(Ⅵ)-induced toxicity in the green alga Chlamydomonas reinhardtii.

Environ Pollut 2021 Mar 31;272:116407. Epub 2020 Dec 31.

Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, China. Electronic address:

The wide range of industrial applications of chromium (Cr) has led to an increasing risk of water contamination by Cr(Ⅵ). However, efficient methods to remove or decrease the toxicity of Cr(Ⅵ) in situ are lacking. The main aim of this study was to investigate the mechanisms by which selenite alleviates chromium(Ⅵ)-induced toxicity in Chlamydomonas reinhardtii. Our results showed that KCrO had toxic effects on both the structure and physiology of C. reinhardtii in a dose-dependent manner. Adding selenite significantly alleviated chromium accumulation and toxicity in cells. RNA-seq data showed that the expression level of selenoproteins such as SELENOH was significantly increased. Both SELENOH-amiRNA knockdown mutants and selenoh insertional mutant produced more reactive oxygen species (ROS) and grew slower than the wild type, suggesting that SELENOH can reduce chromium toxicity by decreasing the levels of ROS produced by Cr(Ⅵ). We also demonstrated that selenite can reduce the absorption of Cr(Ⅵ) by cells but does not affect the process of Cr(Ⅵ) adsorption and efflux. This information on the molecular mechanism by which selenite alleviates Cr(Ⅵ) toxicity can be used to increase the bioremediation capacity of algae and reduce the human health risks associated with Cr(Ⅵ) toxicity.
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http://dx.doi.org/10.1016/j.envpol.2020.116407DOI Listing
March 2021

Enriched isotope tracing to reveal the fractionation and lability of legacy and newly introduced cadmium under different amendments.

J Hazard Mater 2021 02 17;403:123975. Epub 2020 Sep 17.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.

The newly introduced Cd (Cd) has different environmental fates than legacy Cd (Cd) and how to distinguish them in soil under different amendments is crucial for understanding natural aging and engineered remediation of Cd pollution in soil. In this study, enriched stable isotope tracer (Cd) was introduced to distinguish the fate of Cd and Cd in paddy soil under pH adjustment and quicklime, slaked lime, and biochar amendments. The behaviors of Cd and Cd were studied during 56 days of flooding incubation through overlying water analysis, sequential extraction fractionation and lability (exchangeable pool probed by Cd isotopic spike) assessment. The results showed that soil pH is the main driving factor controlling the partition of both Cd and Cd in overlying water. During the incubation, Cd transformed quickly from soluble fraction to residual fraction under all treatments. In addition, at the end of the incubation, Cd concentrations in residual fraction were much higher than that of Cd, suggesting a more thorough aging of Cd than Cd. The labile Cd (ECd) under pH adjustment and biochar amendment decreased during incubation and ECd% was essentially the same with that of ECd% after 28 days, indicating the aging equilibrium of exchangeable pool of Cd.
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http://dx.doi.org/10.1016/j.jhazmat.2020.123975DOI Listing
February 2021

Periphyton as an important source of methylmercury in Everglades water and food web.

J Hazard Mater 2021 05 12;410:124551. Epub 2020 Nov 12.

Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, 11200 SW 8th ST, Miami, FL 33199, USA; Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address:

Periphyton is ubiquitous in Florida Everglades and has a profound effect on mercury (Hg) cycling. Enhanced methylmercury (MeHg) production in periphyton has been well documented, but the re-distribution of MeHg from periphyton remains unknown. In this study, periphyton, sediments, surface water, periphyton overlying water, and periphyton porewater were collected from Everglades for analyzing the distribution of MeHg and total Hg (THg). Results showed that there were no significant differences in THg and MeHg in different types of periphyton, but they all displayed higher MeHg levels than sediments. MeHg distribution coefficients (logk) in periphyton were lower than in sediments, suggesting that periphyton MeHg could be more labile entering aquatic cycling and bioaccumulation. In water, the more the distance of water samples taken from periphyton, the lower the MeHg and dissolved organic carbon concentrations were detected. In extracellular polymeric substances of periphyton, MeHg in colloidal fractions was significantly higher than that in capsular fractions. It was estimated that approximately 10% (or 1.35 kg) of periphyton MeHg were passed on to mosquitofish entering the food web during wet season, contributing 73% of total Hg stocked in mosquitofish. These results revealed the importance of periphyton on water MeHg distribution and MeHg bioaccumulation in Everglades.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124551DOI Listing
May 2021

Monitoring AuNP Dynamics in the Blood of a Single Mouse Using Single Particle Inductively Coupled Plasma Mass Spectrometry with an Ultralow-Volume High-Efficiency Introduction System.

Anal Chem 2020 11 6;92(22):14872-14877. Epub 2020 Oct 6.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, P. R. China.

Gold nanoparticles (AuNPs) are increasingly being used as diagnostic and therapeutic agents owing to their excellent properties; however, there is not much data available on their dynamics in vivo on a single particle basis in a single mouse. Here, we developed a method for the direct analysis of nanoparticles in trace blood samples based on single particle inductively coupled plasma-mass spectrometry (spICP-MS). A flexible, highly configurable, and precisely controlled sample introduction system was designed by assembling an ultralow-volume autosampler (flow rate in the range of 5-5000 μL/min) and a customized cyclonic spray chamber (transfer efficiency up to 99%). Upon systematic optimization, the detection limit of the nanoparticle size (LOD) of AuNPs in ultrapure water was 19 nm, and the detection limit of the nanoparticle number concentration (LOD) was 8 × 10 particle/L. Using a retro-orbital blood sampling method and subsequent dilution, the system was successfully applied to track the dynamic changes in size and concentration for AuNPs in the blood of a single mouse, and the recovery for the blood sample was 111.74%. Furthermore, the concentration of AuNPs in mouse blood reached a peak in a short period of time and, then, gradually decreased. This study provides a promising technique for analyzing and monitoring the size and concentration of nanoparticles in ultralow-volume blood samples with low concentrations, making it a powerful tool for analyzing and understanding the fate of nanoparticles in vivo.
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http://dx.doi.org/10.1021/acs.analchem.0c02285DOI Listing
November 2020

The Crucial Role of Environmental Coronas in Determining the Biological Effects of Engineered Nanomaterials.

Small 2020 09 11;16(36):e2003691. Epub 2020 Aug 11.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.

In aquatic environments, a large number of ecological macromolecules (e.g., natural organic matter (NOM), extracellular polymeric substances (EPS), and proteins) can adsorb onto the surface of engineered nanomaterials (ENMs) to form a unique environmental corona. The presence of environmental corona as an eco-nano interface can significantly alter the bioavailability, biocompatibility, and toxicity of pristine ENMs to aquatic organisms. However, as an emerging field, research on the impact of the environmental corona on the fate and behavior of ENMs in aquatic environments is still in its infancy. To promote a deeper understanding of its importance in driving or moderating ENM toxicity, this study systemically recapitulates the literature of representative types of macromolecules that are adsorbed onto ENMs; these constitute the environmental corona, including NOM, EPS, proteins, and surfactants. Next, the ecotoxicological effects of environmental corona-coated ENMs on representative aquatic organisms at different trophic levels are discussed in comparison to pristine ENMs, based on the reported studies. According to this analysis, molecular mechanisms triggered by pristine and environmental corona-coated ENMs are compared, including membrane adhesion, membrane damage, cellular internalization, oxidative stress, immunotoxicity, genotoxicity, and reproductive toxicity. Finally, current knowledge gaps and challenges in this field are discussed from the ecotoxicology perspective.
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http://dx.doi.org/10.1002/smll.202003691DOI Listing
September 2020

On-line determination of soluble Zn content and size of the residual fraction in PM incubated in various aqueous media.

Sci Total Environ 2020 Jul 30;724:138309. Epub 2020 Mar 30.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.

Transition metals in airborne particulate matter, especially those with aerodynamic diameters no more than 2.5 μm (PM), have attracted considerable attention due to their potential environmental and human health risks. However, determination of these potential risks requires comprehensive knowledge of their dissolution behavior and residual size in aqueous media. Herein, we describe an analytical method for on-line determination of the soluble fraction of Zn as a model transition metal and the size of residual PM using hollow fiber flow field-flow fractionation (HF5) coupled with UV-vis absorption spectroscopy and inductively coupled plasma optical emission spectroscopy. HF5 was directly applied on the incubated samples in pure water (PW), simulated natural water (SNW), and simulated lung fluid (SLF) due to its efficient in-line filtration and excellent fractionation resolution. Firstly, the potential of the proposed method (under optimized conditions) for size characterization was assessed against commercial silica microparticles, and results in good agreement with manufacturer and scanning electron microscopy values were obtained. The accuracy of quantification of soluble Zn in various media was then validated using a standard reference material in terms of satisfactory recoveries compared with the reference values. For the real PM samples collected from different sites in Beijing, China, the soluble Zn percentages in PW, SNW, and SLF were within 15.4-16.7%, 10.6-12.7%, and 43.1-46.9%, respectively, with the amount of particles smaller than ~10 nm released from PM increasing in the order of SNW < PW < SLF. The proposed HF5-based method provides a powerful and efficient tool for the quantification of soluble transition metal fractions and size characterization of residual particles with reduced analysis times, thus possessing great promise in real-time tracking of the transformation of PM in environmental and physiological media and in risk assessment.
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http://dx.doi.org/10.1016/j.scitotenv.2020.138309DOI Listing
July 2020

Mitigation of methylmercury production in eutrophic waters by interfacial oxygen nanobubbles.

Water Res 2020 Apr 30;173:115563. Epub 2020 Jan 30.

Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China; Beijing Advanced Science and Innovation Center, Chinese Academy of Sciences, Beijing, 101407, PR China; Center of Integrated Water-Energy-Food Studies (iWEF), School of Animal, Rural, and Environmental Sciences, Nottingham Trent University, Brackenhurst Campus, NG25 0QF, UK. Electronic address:

In mercury (Hg)-polluted eutrophic waters, algal blooms are likely to aggravate methylmercury (MeHg) production by causing intensified hypoxia and enriching organic matter at the sediment-water interface. The technology of interfacial oxygen (O) nanobubbles is proven to alleviate hypoxia and may have potential to mitigate the risks of MeHg formation. In this study, incubation column experiments were performed using sediment and overlying water samples collected from the Baihua Reservoir (China), which is currently suffering from co-contamination of Hg and eutrophication. The results indicated that after the application of O nanobubbles, the %MeHg (ratio of MeHg to total Hg) in the overlying water and surface sediment decreased by up to 76% and 56% respectively. In addition, the MeHg concentrations decreased from 0.54 ± 0.15 to 0.17 ± 0.01 ng L in the overlying water and from 56.61 ± 9.23 to 25.48 ± 4.08 ng g in the surface sediment. The decline could be attributed to the alleviation of anoxia and the decrease of labile organic matter and bioavailable Hg. In addition, hgcA gene abundances in the overlying water and surface sediment decreased by up to 69% and 44% after the addition of O nanobubbles, as is consistent with MeHg occurrence in such areas. Accordingly, this work proposed a promising strategy of using interfacial oxygen nanobubbles to alleviate the potentially enhanced MeHg production during algal bloom outbreaks in Hg-polluted eutrophic waters.
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http://dx.doi.org/10.1016/j.watres.2020.115563DOI Listing
April 2020

In Situ Tracking Photodegradation of Trace Graphene Oxide by the Online Coupling of Photoinduced Chemical Vapor Generation with a Point Discharge Optical Emission Spectrometer.

Anal Chem 2020 01 24;92(1):1549-1556. Epub 2019 Dec 24.

State Key Laboratory of Environmental Chemistry and Ecotoxicology , Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , 100085 Beijing , P. R. China.

The photostability of graphene oxide (GO) strongly affects the performance of its products in optics and photonics. However, the photostability of GO, especially at trace levels, remains largely unexplored mainly because of the lack of available techniques. Herein, we developed a novel online system consisting of a highly efficient photoinduced chemical vapor generation reactor and an in situ measurement technique using a miniaturized and sensitive point discharge optical emission spectrometer. On the basis of the results of inorganic carbon species, abundant oxygen-containing functional groups on GO nanosheets made the degradation much easier than graphene. Under the optimized conditions (e.g., initial pH of 2.8 and binary photocatalysts dose of 200 mM HO, 1.0 mM Fe ions, and 50 mg/L TiO NPs), the limit of detection for GO was 87.5 μg/L C with a linear range of 0.5-10 mg/L C. Specifically, the accuracy and reliability of the developed system was verified by quantifying self-prepared GO as well as aggregated GO in natural organic matter-rich water samples. Finally, the sunlight-induced photodegradation of GO under simulated environmental conditions was successfully tracked. The developed system is a promising platform for in-time quality control of GO-based products as well as predicting the occurrence, transformation, and fate of GO at environmentally relevant concentrations in the natural aquatic environment.
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http://dx.doi.org/10.1021/acs.analchem.9b04837DOI Listing
January 2020

Light absorption, fluorescence properties and sources of brown carbon aerosols in the Southeast Tibetan Plateau.

Environ Pollut 2020 Feb 14;257:113616. Epub 2019 Nov 14.

Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Beijing 100101, China; Center for Excellence in Tibetan Plateau Earth Sciences, CAS, Beijing 100101, China. Electronic address:

Brown carbon (BrC) has been proposed as an important driving factor in climate change due to its light absorption properties. However, our understanding of BrC's chemical and optical properties are inadequate, particularly at remote regions. This study conducts a comprehensive investigation of BrC aerosols in summer (Aug. 2013) and winter (Jan. 2014) at Southeast Tibetan Plateau, which is ecologically fragile and sensitive to global warming. The concentrations of methanol-soluble BrC (MeS-BrC) are approximately twice of water-soluble BrC (WS-BrC), demonstrating the environmental importance of water-insoluble BrC are previously underestimated with only WS-BrC considered. The mass absorption efficiency of WS-BrC (0.27-0.86 m g) is lower than those in heavily polluted South Asia, indicating a distinct contrast between the two sides of Himalayas. Fluorescence reveals that the absorption of BrC is mainly attributed to humic-like and protein-like substances, which broaden the current knowledge of BrC's chromophores. Combining organic tracer, satellite MODIS data and air-mass backward trajectory analysis, this study finds BrC is mainly derived from bioaerosols and secondary formation in summer, while long-range transport of biomass burning emissions in winter. Our study provides new insights into the optical and chemical properties of BrC, which may have implications for environmental effect and sources of organic aerosols.
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http://dx.doi.org/10.1016/j.envpol.2019.113616DOI Listing
February 2020

Tracking Mercury in Individual Using a Capillary Single-Cell Inductively Coupled Plasma Mass Spectrometry Online System.

Anal Chem 2020 01 4;92(1):622-627. Epub 2019 Dec 4.

State Key Laboratory of Environmental Chemistry and Ecotoxicology , Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085 , China.

As a kind of unicellular eukaryotic protozoa, is located at the bottom of the aquatic food webs and plays an essential role in the bioaccumulation of mercury (Hg). To track Hg in individual , a capillary single-cell inductively coupled plasma mass spectrometry (ICPMS) online system was developed. The experimental and instrumental conditions were optimized to ensure the signal detected was the Hg uptake in individual . Moreover, a quantitative method was established and validated by detecting Hg standard solutions. The limit of quantity was calculated to be approximately 3.8 × 10 g Hg/cell, and the detection limit for Hg exposure of was 0.05 μg/L. By using the proposed method, we found the peak became wider with increasing of exposure concentrations, indicating the accumulated Hg by different varied greatly, and the difference was more significant at higher exposure concentration. This novel method has the advantages of high sensitivity and real-time detection in individual , and it could be widely used for further tracking the accumulation of mercury and other metals at the single cell level.
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http://dx.doi.org/10.1021/acs.analchem.9b03719DOI Listing
January 2020

Occurrence and leaching of silver in municipal sewage sludge in China.

Ecotoxicol Environ Saf 2020 Feb 10;189:109929. Epub 2019 Nov 10.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, United States.

Sewage treatment plants effectively remove silver (Ag) from sewage. Sewage sludge can therefore be important Ag sinks, polluting the environment with this element. In this work, we report a nation-wide survey on the Ag content of sewage sludge in China (0.23-19.02 mg kg, average 2.72 mg kg). Furthermore, we identify that sludge disposal represents an important Ag pollution source (84.48 tons in 2016) for the environment by estimating the national and provincial inventories of sludge-borne Ag in China. Also the positive correlations between the per capita gross domestic product (GDP)/provincial GDP and the content/mass loadings of Ag highlighted the impact of human activities on Ag pollution. In different samples, strong complexation of thiosulfate contributed to the highest leaching concentration (95.00-438.15 μg kg) and ratio (1.9-8.8%) of Ag, emphasizing the necessity of a long-term risk assessment for landfill and land application of sludge.
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http://dx.doi.org/10.1016/j.ecoenv.2019.109929DOI Listing
February 2020

Cadmium-binding proteins in human blood plasma.

Ecotoxicol Environ Saf 2020 Jan 6;188:109896. Epub 2019 Nov 6.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.

Blood is the transmission medium for metal contaminants to and from bodily organs; as such, it can provide useful and reliable information about their bio-kinetics as they're distributed throughout the body. Metals can interact with endogenous proteins present in the blood, and these metal-protein complexes often dictate the fates of the introduced metals. The aim of this study was to investigate cadmium-binding protein characteristics in normal human plasma. Cadmium-binding plasma proteins in two different groups: normal human plasma (n = 29), and normal paired maternal and fetal umbilical cord plasmas (n = 3), were analyzed. In order to detect cadmium-binding plasma proteins present in low concentrations, blood plasma samples were first depleted of their two most abundant proteins - albumin and immunoglobulin G. Both the crude and depleted plasma samples were analyzed using column gel electrophoresis in conjunction with Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). One cadmium-binding protein was detected in 11 of 29 normal plasma samples and all three paired maternal and cord plasma samples. This protein was further identified as apolipoprotein A-I by high-resolution mass spectrometry. To the best of our knowledge, this is the first study to reveal cadmium-binding proteins in real human blood plasma, which is extremely critical to our understanding of cadmium transportation and accumulation in human blood.
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http://dx.doi.org/10.1016/j.ecoenv.2019.109896DOI Listing
January 2020

Freezing Facilitates Formation of Silver Nanoparticles under Natural and Simulated Sunlight Conditions.

Environ Sci Technol 2019 Dec 15;53(23):13802-13811. Epub 2019 Nov 15.

State Key Laboratory of Environmental Chemistry and Ecotoxicology , Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085 , China.

Freezing is essential in the light-mediated transformation of organic pollutants. However, the effects of the freezing process on the reduction of Ag by natural organic matter (NOM) remains unclear, causing significant uncertainties in the natural formation of silver nanoparticles (AgNPs). This study investigated the sunlight-induced reduction of Ag by NOM under natural or controlled freezing processes. Natural (outdoor) freezing experiments demonstrated intense aggregation and precipitation of AgNPs in three aqueous media, including a NOM solution and two river water samples, under natural sunlight irradiation. Indoor experiments under simulated sunlight irradiation and controlled freezing processes showed that freezing at -20 °C and repeated freeze-thaw cycles (-20 to 4 °C) drastically accelerated the formation and growth of AgNPs compared to maintenance at 4 °C. Finally, under the natural freezing process, commercial AgNPs were found to influence the redox reduction of Ag probably through a reduction in dissolution rates and homoaggregation with AgNPs newly formed in the river water samples. Additionally, the enhancement effect of freezing on AgNP formation was confirmed in the presence of Ag and AgNPs both at environmentally relevant concentration levels, especially upon light irradiation. This work emphasizes the importance of freezing processes on the natural formation of AgNPs.
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http://dx.doi.org/10.1021/acs.est.9b05926DOI Listing
December 2019

Length and diameter-dependent phagocytosis and cytotoxicity of long silver nanowires in macrophages.

Chemosphere 2019 Dec 10;237:124565. Epub 2019 Aug 10.

Key Laboratory of Environmental Nanotechnology and Health Effects, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China. Electronic address:

Long silver nanowires (AgNWs, >5 μm) have shown promising applications in next generation biomaterials. However, the toxicity of long AgNWs is not well characterized in terms of their size. In this study, five AgNWs types, including SAgNW30 (length: 5-10 μm; diameter: 30 nm), MAgNW30 (length: 20-30 μm; diameter: 30 nm), LAgNW30 (length: ∼100 μm; diameter: 30 nm), LAgNW50 (length: ∼100 μm; diameter: 50 nm), and LAgNW100 (length: ∼100 μm; diameter: 100 nm), were used to investigate the size-dependent phagocytosis and cytotoxicity in macrophage. It showed that SAgNW30, MAgNW30, LAgNW30 can be fully phagocytosed by macrophages, but LAgNW50 and LAgNW100 frustrated the phagocytosis. It demonstrated that LAgNW30 can be internalized into macrophage in a curly manner. The size-dependent cytotoxicity was observed in cell viability, apoptosis, mitochondrial damage, phenotypic transition, and inflammatory response in AgNWs-treated macrophage. The AgNWs-induced cytotoxicity was depended on their length and diameter, increased gradually in the order of SAgNW30 > MAgNW30 > LAgNW30 > LAgNW50 > LAgNW100. The findings presented here will assist in the evaluation of the size-dependent cytotoxicity mediated by long AgNWs.
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http://dx.doi.org/10.1016/j.chemosphere.2019.124565DOI Listing
December 2019

Scattered Light Imaging Enables Real-Time Monitoring of Label-Free Nanoparticles and Fluorescent Biomolecules in Live Cells.

J Am Chem Soc 2019 09 9;141(36):14043-14047. Epub 2019 Aug 9.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085 , People's Republic of China.

Simultaneously monitoring label-free nanoparticles (NPs) and fluorescent biomolecules inside the live cell in real time is challenging because both imaging methods require different instrumentation and measuring principles. Here we report a novel scattered light imaging (SLi) technique that allows label-free NPs to be monitored using a conventional confocal microscope. The method shows a high spatial resolution and can distinguish label-free silver nanoparticles (AgNPs) with a 10 nm size difference in live cells. We performed SLi to observe the uptake, movement, distribution, and transformation of AgNPs in live cells at a single-particle level. The method is applicable to accurately track the localization of a variety of nanomaterials inside the cell. With this approach, label-free NP and fluorescent-labeled biomolecules are imaged simultaneously making it possible to real-time monitor nanobio interactions.
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http://dx.doi.org/10.1021/jacs.9b05894DOI Listing
September 2019

Different circulation history of mercury in aquatic biota from King George Island of the Antarctic.

Environ Pollut 2019 Jul 24;250:892-897. Epub 2019 Apr 24.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China.

To trace the circulation history of aquatic bioavailable Hg in the Antarctic, the species and isotopic compositions of Hg in sediment, Archaeogastropoda (Agas), Neogastropoda (Ngas), and fish collected from King George Island were studied in detail. Positive mass independent fractionation (MIF) was observed and positively correlated with the percentages of methylmercury (MeHg%) in Agas and Ngas, suggesting an effect of MeHg accumulation during trophic transfer on MIF signatures. However, both the ratios of ΔHg/δHg and ΔHg/ΔHg indicated different circulation histories of Hg in Agas, Ngas, and fish. The microbial methylation in sediment was the primary source of MeHg in Agas and Ngas (ΔHg/δHg ∼0, ΔHg/ΔHg ∼1.00). In contrast, the MeHg in fish (ΔHg/δHg = 0.55 ± 0.06, ΔHg/ΔHg = 1.19 ± 0.17) came from the combined sources of residual MeHg which had sunk from the surface water and microbial-methylated MeHg in sediments, and the bioavailable Hg in the sediments contributed to approximately 44% of the total Hg in fish. Subsequently, the ΔHg values of bioavailable MeHg and IHg in sediments were quantitatively calculated, which provided key end-member information for future source apportionment in the Antarctic and other pelagic regions. It was also found that the Hg accumulated in Agas and Ngas had no history of MeHg photo-degradation, indicating that the methylated Hg in benthic zones suffered little photo-degradation and thus presented high bioavailability and environmental risk.
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http://dx.doi.org/10.1016/j.envpol.2019.04.113DOI Listing
July 2019

Ultra-long silver nanowires induced mitotic abnormalities and cytokinetic failure in A549 cells.

Nanotoxicology 2019 05 19;13(4):543-557. Epub 2019 Feb 19.

c State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , Beijing , China.

Asbestos fiber has been associated with mesothelioma and lung cancer. However, the carcinogenic risks of other fiber nanomaterials with morphological similarities to asbestos have not been fully studied. Ultra-long silver nanowires (AgNWs) are increasingly used fiber-shaped nanomaterials with a high aspect ratio, but very few studies have investigated their health risks. Here, proliferation abnormalities of lung epithelial cells induced by ultra-long AgNWs were investigated. Ultra-long AgNW treatment induced dose- and diameter-dependent increase in the ratio of multinucleated cells. Further, proteins involved in mitosis and cytokinesis, including Aurora A, p-Histone 3 (ser10), RhoA, p-MLC, and myosin IIb, were significantly upregulated after an ultra-long AgNW treatment, leading to mitotic abnormalities and cytokinetic failure. Meanwhile, exposure to ultra-long AgNWs induced cell cycle arrest. Interestingly, a series of experiments demonstrated that ROS generation and Ag release were not responsible for the multinucleation induced by ultra-long AgNWs, but ultra-long AgNWs in the intercellular bridge might obstruct the contractile ring and inhibit abscission of the cytokinetic furrow by direct physical contact. Altogether, our findings indicate that ultra-long AgNWs can induce chromosomal instability, which has important consequences for the safety of ultra-long AgNWs to human health.
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http://dx.doi.org/10.1080/17435390.2019.1571645DOI Listing
May 2019

Enhanced removal of Cr(VI) by biochar with Fe as electron shuttles.

J Environ Sci (China) 2019 Apr 26;78:109-117. Epub 2018 Jul 26.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.

Biochar is extensively used as an effective soil amendment for environmental remediation. In addition to its strong contaminant sorption capability, biochar also plays an important role in chemical transformation of contaminant due to its inherent redox-active moieties. However, the transformation efficiency of inorganic contaminants is generally very limited when the direct adsorption of contaminants on biochar is inefficient. The present study demonstrates the role of Fe ion as an electron shuttle to enhance Cr(VI) reduction by biochars. Batch experiments were conducted to examine the effects of Fe(III) levels, pyrolysis temperature of biochar, initial solution pH, and biochar dosage on the efficiency of Cr(VI) removal. Results showed a significant enhancement in Cr(VI) reduction with an increase in Fe(III) concentration and a decrease of initial pH. Biochar produced at higher pyrolysis temperatures (e.g., 700°C) favored Cr(VI) removal, especially in the presence of Fe(III), while a higher biochar dosage proved unfavorable likely due to the agglomeration or precipitation of biochar. Speciation analysis of Fe and Cr elements on the surface of biochar and in the solution further confirmed the role of Fe ion as an electron shuttle between biochar and Cr(VI). The present findings provide a potential strategy for the advanced treatment of Cr(VI) at low concentrations as well as an insight into the environmental fate of Cr(VI) and other micro-pollutants in soil or aqueous compartments containing Fe and natural or engineered carbonaceous materials.
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http://dx.doi.org/10.1016/j.jes.2018.07.009DOI Listing
April 2019

Uptake and Transformation of Silver Nanoparticles and Ions by Rice Plants Revealed by Dual Stable Isotope Tracing.

Environ Sci Technol 2019 01 21;53(2):625-633. Epub 2018 Dec 21.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085 , China.

Knowledge on the uptake and transformation of silver nanoparticles (AgNPs) and Ag ions by organisms is critical for understanding their toxicity. Herein, the differential uptake, transformation, and translocation of AgNPs and Ag ions in hydroponic rice ( Oryza sativa L.) is assessed in modified Hewitt (with Cl ions, HS(Cl)) and Hogland solutions (without Cl ions, HS) using dual stable isotope tracing (AgNO and AgNPs). After coexposure to Ag ions and AgNPs at 50 μg L (as Ag for both) for 14 days, a stimulatory effect was observed on root elongation (increased by 68.8 and 71.9% for HS(Cl) and HS, respectively). Most of the Ag ions (from Ag ions and AgNPs) were retained on the root surface, while the occurrence of AgNPs (from AgNPs and Ag ions) was observed in the root, suggesting the direct uptake of AgNPs and/or reduction of Ag ions. Higher fractions of Ag ions in the shoot suggest an in vivo oxidation of AgNPs. These results demonstrated the intertransformation between Ag ions and AgNPs and the role of AgNPs as carriers and sources of Ag ions in organisms, which is helpful for understanding the fate and toxicology of Ag.
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http://dx.doi.org/10.1021/acs.est.8b02471DOI Listing
January 2019

Acute and Sublethal Effects of Ethylmercury Chloride on Chinese Rare Minnow (Gobiocypris rarus): Accumulation, Elimination, and Histological Changes.

Bull Environ Contam Toxicol 2019 May 4;102(5):708-713. Epub 2018 Dec 4.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.

Ethylmercury (EtHg) has been widely observed in the environment due to anthropogenic contamination and/or environmental ethylation of inorganic mercury. Herein, the acute and sublethal effect of EtHg chloride on Chinese rare minnow (Gobiocypris rarus) as a fish model was studied. EtHg chloride showed an obvious toxicity to 4-month-old Chinese rare minnow (LC50 24.8 µg L (as Hg) at 24 h). Histological analysis revealed that acute EtHg exposure can induce necrosis, telangiectasis and exfoliation of epithelial cells in the gill, as well as edema, vacuoles, and pyknotic nuclei in hepatocytes. Sublethal dose exposure revealed a very high accumulation of EtHg in fish, which is subsequently metabolized to inorganic mercury and eliminated after depuration. A new mercury species, possibly diethylmercury, was also observed as the metabolite of EtHg in rare minnow. The present study provides useful information for assessing the risks of EtHg and understanding its bioaccumulation in aquatic organisms.
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http://dx.doi.org/10.1007/s00128-018-2513-3DOI Listing
May 2019

Mechanism of Accumulation of Methylmercury in Rice ( Oryza sativa L.) in a Mercury Mining Area.

Environ Sci Technol 2018 09 21;52(17):9749-9757. Epub 2018 Aug 21.

Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , No. 18 Shuangqing Road , Beijing 100085 , China.

Rice consumption is the primary pathway for methylmercury (MeHg) exposure at inland mercury (Hg) mining areas of China. The sources and processes of formation and translocation for MeHg in rice plant are complex and remain largely unknown. In this study, rice ( Oryza sativa L.) was exposed to isotopically labeled dimethylmercury (DMeHg) in field experiments using open top chambers to explore the response of MeHg accumulation in rice tissues to different levels of DMeHg in air. Rice leaves assimilated DMeHg from air, which was subsequently largely stored in aboveground tissues, including the rice grain, with only a small amount reaching the root. Combining these experimental results with field investigations of DMeHg concentrations in air beneath the rice canopy in a Hg mining area, we estimate that 15.5%, 10.8%, and 8.50% MeHg in the brown rice, the leaf, and the upper stalk, respectively, could be derived from atmospheric sources of DMeHg, while 99.5% of MeHg in rice root originated from the rice soil-water system. These findings help refine the mechanism of MeHg accumulation in rice that, in addition to soil, a fraction of MeHg in rice plants can be derived from DMeHg emissions from flooded rice paddies in Hg mining areas.
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http://dx.doi.org/10.1021/acs.est.8b01783DOI Listing
September 2018

Humic-Like Substances (HULIS) in Aerosols of Central Tibetan Plateau (Nam Co, 4730 m asl): Abundance, Light Absorption Properties, and Sources.

Environ Sci Technol 2018 07 19;52(13):7203-7211. Epub 2018 Jun 19.

Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research , Chinese Academy of Sciences , Beijing 100101 , China.

Humic-like substances (HULIS) are major components of light-absorbing brown carbon that play an important role in Earth's radiative balance. However, their concentration, optical properties, and sources are least understood over Tibetan Plateau (TP). In this study, the analysis of total suspended particulate (TSP) samples from central of TP (i.e., Nam Co) reveal that atmospheric HULIS are more abundant in summer than that in winter without obvious diurnal variations. The light absorption ability of HULIS in winter is 2-3 times higher than that in summer. In winter, HULIS are mainly derived from biomass burning emissions in South Asia by long-range transport. In contrast, the oxidation of anthropogenic and biogenic precursors from northeast part of India and southeast of TP are major sources of HULIS in summer.
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http://dx.doi.org/10.1021/acs.est.8b01251DOI Listing
July 2018
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