Publications by authors named "Gan Zhang"

381 Publications

Identification of RORγ as a favorable biomarker for colon cancer.

J Int Med Res 2021 May;49(5):3000605211008338

Department of Colorectal and Anal Surgery, the Affiliated Hospital of West Anhui Health Vocational College, Lu'an, China.

Objective: To evaluate the expression of retinoid-related orphan receptor gamma (RORγ) and its potential role in the prognosis of colon cancer.

Methods: The Cancer Genome Atlas and GSE117606 were used to evaluate to RORγ levels in colon cancer, and real-time quantitative polymerase chain reaction was applied for validation. UALCAN and MEXPRESS were used to analyze the associations of RORγ expression with clinical parameters. The survival analysis was conducted in GEPIA.

Results: RORγ expression was significantly lower in colon tumors than in adjacent normal mucosa tissues. RORγ expression was significantly associated with tumor stage, lymph node metastasis, and liver metastasis. The area under the curve for diagnosis was 0.71. Decreased RORγ expression was positively correlated with the incidence of lymphatic invasion, microsatellite instability, the presence of residual tumor, venous invasion, and copy number variation. Overall survival was longer in patients with higher RORγ expression, especially those with microsatellite instability-high features. Methylation analysis revealed that hypermethylation of the RORγ promoter was associated with the colon cancer stage.

Conclusions: RORγ downregulation could be a potential biomarker for colon cancer, especially for predicting prognosis. Decreased RORγ expression in colon tumor may be associated with promoter hypermethylation.
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http://dx.doi.org/10.1177/03000605211008338DOI Listing
May 2021

Uptake and translocation of organophosphate esters by plants: Impacts of chemical structure, plant cultivar and copper.

Environ Int 2021 Apr 29;155:106591. Epub 2021 Apr 29.

State Key Laboratory of Organic Geochemistry and Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China.

Organophosphate esters (OPEs) are normally used as flame retardants, plasticizers and lubricants, but have become environmental pollutants. Because OPEs are normally present alongside heavy metals in soils, the effects of interactions between OPEs and heavy metals on plant uptake of OPEs need to be determined. In this study, we investigated the effects of OPEs chemical structure, plant cultivar and copper (Cu) on the uptake and translocation of OPEs by plants. The bioaccumulation of OPEs varied among plant cultivars. They were preferentially enriched in carrot, with the lowest concentrations observed in maize. OPEs with electron-ring substituents (ER-OPEs) exhibited a higher potential for root uptake than did OPEs with open-chain substituents (OC-OPEs), which could be attributed to the higher sorption of ER-OPEs onto root charged surfaces. This was explained by the stronger noncovalent interactions with the electron-rich structure of ER-OPEs. The presence of Cu slightly reduced the distinct difference in the ability of roots to take up OC-OPEs and ER-OPEs. This was explained by the interactions of Cu ions with the electron-rich structure of ER-OPEs, which suppressed the sorption of ER-OPEs on the root surface. A negative relationship between the logarithms of the translocation factor and octanol-water partition coefficient (K) was observed in treatments with either OPEs only or OPEs + Cu, implying the significant role of hydrophobicity in the OPEs acropetal translocation. The results will improve our understanding of the uptake and translocation of OPEs by plant cultivars as well as how the process is affected by the chemical structure of OPEs and Cu, leading to improvements in the ecological risk assessment of OPEs in the food chain.
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http://dx.doi.org/10.1016/j.envint.2021.106591DOI Listing
April 2021

Daytime sleepiness might increase the risk of ALS: a 2-sample Mendelian randomization study.

J Neurol 2021 Apr 29. Epub 2021 Apr 29.

Department of Neurology, Peking University Third Hospital, 49 North Garden Road, Haidian District, Beijing, 100191, China.

Background: Observational studies have indicated that there is a high prevalence of habitual sleep disturbances in amyotrophic lateral sclerosis (ALS). However, the actual relationship between these symptoms and ALS remains unclear.

Methods: We used 2-sample Mendelian randomization to determine whether the sleep disturbances associated with ALS are also related to the risk of ALS. The summary statistics we used were from recent, large genome-wide association studies on daytime sleepiness and other night sleep traits (n = 85,670-452,071) and ALS (n = 20,806 cases, n = 59,804 controls). The inverse variance-weighted (IVW) method was used as the main method for assessing causality.

Results: Daytime sleepiness might increase the risk of ALS (IVW odds ratio = 2.45, 95% confidence interval: 1.15-5.21; P = 0.020). ALS was not associated with sleep efficiency, number of sleep episodes or sleep duration.

Conclusions: Our results provide novel evidence that daytime sleepiness increases the risk of ALS and points out the importance of daytime sleepiness that often goes unnoticed in ALS.
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http://dx.doi.org/10.1007/s00415-021-10564-zDOI Listing
April 2021

Decade-scale change in testate amoebae community primarily driven by anthropogenic disturbance than natural change in a large subtropical reservoir.

Sci Total Environ 2021 Apr 20;784:147026. Epub 2021 Apr 20.

Aquatic EcoHealth Group, Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China. Electronic address:

Understanding the extent of human activities leading to an influx of chemical pollutants that cause substantial environmental transformations is the focus of much ongoing research. In this study, we present a multi-proxy record based on a sediment core from a large subtropical reservoir (Xinfengjiang Reservoir) in south China with an emphasis on the changes in testate amoebae community, in combination with sedimentological (radioactivity, physicochemistry, nutrient and organochlorine pesticides) and climatological (air temperature and precipitation) data over the last three decades. Twenty-seven testate amoebae species belonging to seven genera (Arcella, Centropyxis, Cyclopyxis, Difflugia, Netzelia, Euglypha and Pseudodifflugia) were observed. Species richness, abundance and biomass of testate amoebae were in ranges of 18-26 species, 616-825 ind. ml and 9.0-19.4 μg C ml, respectively. Two development stages of the reservoir, dated to 1978-1993 (stage 1) and 1993-2006 (stage 2), were distinguished based on testate amoebae communities. Stage 1 was characterized by elevated dry bulk density, carbon-to‑nitrogen ratio and p,p'-DDE in the sediment core and an impact of nitrogen and sulfur deficiency on testate amoebae. Stage 2 was marked by a decrease of dry bulk density, elevated concentrations of aluminum, iron and carbon, low carbon-to‑nitrogen ratio and organochlorine pesticides, fluctuations in rainfall on shorter and yearly timescales, and a stronger influence of the organochlorine pesticides on testate amoebae. Testate amoebae community change and the identified two-stage development were consistent with atmospheric deposition of organochlorine pesticides from anthropogenic sources inside and outside the reservoir watershed, nutrient influx and sediment physicochemistry. The testate amoebae community dynamics and a strong community-environment relationship in stage 2 were linked with non-random patterns in the biotic neighborhoods of species (deterministic processes). The results suggest a stronger impact of anthropogenic disturbance than natural environmental change on testate amoebae community variation of Xinfengjiang Reservoir over time.
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http://dx.doi.org/10.1016/j.scitotenv.2021.147026DOI Listing
April 2021

Dual-isotope-based source apportionment of nitrate in 30 rivers draining into the Bohai Sea, north China.

Environ Pollut 2021 Apr 12;283:117112. Epub 2021 Apr 12.

State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China.

Excessive nitrate (NO) in rivers can lead to water quality deterioration, and can also be directly input into estuaries and oceans, thus posing a serious threat to the stability of their ecosystems. In this study, the concentration, isotopes and sources of NO in 30 rivers discharging into the Bohai Sea were comprehensively investigated. The mean concentration of NO-N was 2.24 ± 2.11 mg L, with obvious seasonal and spatial variations. In total, 104.24 kt of NO-N was discharged into the Bohai Sea annually, to which the Yellow River Basin and Liao River Basin made the largest contributions. The range of δN-NO was -1.1‰ to +33.2‰ (mean value, +11.4 ± 5.0‰), with no significant seasonal or spatial differences; the mean value of δO-NO was +9.4 ± 7.2‰, with much higher values seen in June. Based on the MixSIAR model, manure (24.3 ± 7.5%) and sewage (19.1 ± 14.5%) were the primary sources of NO in the 30 rivers, followed by NO fertilizers (16.3 ± 12.5%), soil N (15.5 ± 11.9%), atmospheric deposition of NO (13.5 ± 5.7%) and NH fertilizers (11.4 ± 8.9%). This finding highlights the vital roles of sewage and manure management in riverine NO. Using a mathematical method, the contributions of various sources to each river were simulated. The results indicated that management of the Yellow River, Daliao River, Liao River, and Xiaoqing River is more urgently needed than that of other rivers to control Bohai NO pollution. We believe that this finding will provide guidance for scientific management of NO pollution in these 30 rivers and the Bohai Sea.
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http://dx.doi.org/10.1016/j.envpol.2021.117112DOI Listing
April 2021

Insights into Persistent Toxic Substances in Protective Cases of Mobile Phones: Occurrence, Health Risks, and Implications.

Environ Sci Technol 2021 05 15;55(9):6076-6086. Epub 2021 Apr 15.

State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.

Despite the popularity of smartphones worldwide, persistent toxic substances (PTSs) in protective cases of mobile phones (PCMPs) and their health risks via direct skin contact have been ignored. This study investigated PTSs in PCMPs made in China with different materials and sales territory and their potential harm to human health. Polybrominated diphenyl ethers (PBDEs, 6.40 ng/g), new brominated flame retardants (NBFRs, 144 ng/g), organophosphate esters (OPEs, 10.1 μg/g), short-chain chlorinated paraffins (SCCPs, 3.58 μg/g), medium-chain chlorinated paraffins (MCCPs, 3.17 μg/g), and heavy metals (HMs, 72.3 μg/g) were detected. It was found that the different concentrations and compositions depend on the material, region, and use. Moreover, the raw materials used to fabricate PCMPs are of variable quality and may include recycled plastic waste. There are no standard quality specifications for PCMPs, and different materials have different properties, including specific surface area and adsorption ability. The risk assessment performed by Monte Carlo simulations indicated that the PTSs evaluated pose no health risks to the general population and may have adverse effects on individual high-exposure populations. According to the results of this work, it is suggested that more stringent global specifications for the selection of raw materials should be established, including the content and structural characteristics of PTSs, limitations on the use of additives in the production process, and the handling after use.
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http://dx.doi.org/10.1021/acs.est.0c07603DOI Listing
May 2021

BMSC seeding in different scaffold incorporation with hyperbaric oxygen treats seawater-immersed bony defect.

J Orthop Surg Res 2021 Apr 13;16(1):249. Epub 2021 Apr 13.

Department of Orthopaedics, The 901th Hospital of the Joint Logistics Support Force of the Chinese People's Liberation Army, Hefei, 230031, China.

Introduction: The experiment was undertaken to estimate the effect of BMSC seeding in different scaffold incorporation with HBO on the repair of a seawater-immersed bone defect. And future compared n-HA/PLGA with β-TCP/PLGA as a scaffold in treatment effect of the seawater-immersed bone defect.

Methods: Sixty New Zealand White rabbits with standard seawater defect in radius were randomly divided into group A (implant with nothing), group B (implanted with autogenous bone), group C (implanted with n-HA/PLGA/BMSCs), and group D (implanted with β-TCP/PLGA/BMSCs). After the implant, each rabbit receives HBO treatment at 2.4 ATA 100% oxygen for 120 min/day for 2 weeks. Radiograph, histological, and biomechanical examinations were used to analyze osteogenesis.

Result: X-ray analysis shows that n-HA/PLGA/BMSCs and β-TCP/PLGA/BMSCs could accelerate the new bone formation, and the new bone formation in group C was larger than that in group D or group A and close to group B (P < 0.05). After 12 weeks, in group A, the defect without scaffold shows a loose connect tissue filled in the areas. The medullary canal in group B was recanalized. Defects in groups C and D show a larger number of woven bone formation. The new woven bone formation in defect areas in group C was larger than that in group D. The mechanical examination revealed ultimate strength at 12 weeks was group D > group C > group B > group A (P < 0.05).

Conclusion: Scaffolds of n-HA/PLGA and β-TCP/PLGA incorporation with HBO and BMSCs were effective to treat seawater-immersed bone defect, and n-HA/PLGA was more excellent than β-TCP/PLGA.
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http://dx.doi.org/10.1186/s13018-021-02368-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8042966PMC
April 2021

Probing Legacy and Alternative Flame Retardants in the Air of Chinese Cities.

Environ Sci Technol 2021 Mar 23. Epub 2021 Mar 23.

State Key Laboratory of Organic Geochemistry and Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.

An increasing number of alternative flame retardants (FRs) are being introduced, following the international bans on the use of polybrominated diphenyl ether (PBDE) commercial mixtures. FRs' production capacity has shifted from developed countries to developing countries, with China being the world's largest producer and consumer of FRs. These chemicals are also imported with e-waste to China. Therefore, it is important to understand the current status of regulated brominated FRs, their phase-out in China, and their replacement by alternatives. In this study, a broad suite of legacy and alternative FRs, including eight PBDEs, six novel brominated FRs (NBFRs), two dechlorane plus variants (DP), and 12 organophosphate FRs (OPFRs) were evaluated in the air of 10 large Chinese cities in 2018. OPFRs are the most prevalent FRs in China, exhibiting a wide range of 1-612 ng/m, which is several orders of magnitude higher than PBDEs (1-1827 pg/m) and NBFRs (1-1428 pg/m). BDE 209 and DBDPE are the most abundant compounds in brominated FRs (>80%). The North China Plain (NCP, excluding Beijing), Guangzhou, and Lanzhou appear to be three hotspots, although with different FR patterns. From 2013/2014 to 2018, levels of PBDEs, NBFRs, and DPs have significantly decreased, while that of OPFRs has increased by 1 order of magnitude. Gas-particle partitioning analysis showed that FRs could have not reached equilibrium, and the steady-state model is better suited for FRs with a higher log (>13). To facilitate a more accurate FR assessment in fine particles, we suggest that, in addition to the conventional volumetric concentration (pg/m), the mass-normalized concentration (pg/g PM) could also be used.
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http://dx.doi.org/10.1021/acs.est.0c07367DOI Listing
March 2021

Role of low-latitude forests in modulating forest filter effect on a continental scale: Long-term simulation on PCB-153 in Chinese forests.

Sci Total Environ 2021 Mar 8;778:146285. Epub 2021 Mar 8.

State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.

Forests are important compartments influencing the environmental fate of persistent organic pollutants (POPs). To illustrate the effect of forests on the regional cycle of POPs, a level IV fugacity fate and transport model coupled with a detailed dynamic-forest module was applied to simulate the long-term variations of PCB-153 in China, where forest coverage accounts for approximately one fifth of land area. In the scenarios with forests, atmospheric outflow from China was 69% of that in the scenario without forests due to the enhanced storage in soil, degradation, and leaching. Previous studies regarded high-latitude areas, such as the polar region and boreal forests, as environments capable of reducing mobility of PCB-153, and they act as sinks of POPs. This modeling result suggests that tropical and subtropical forests may also play a similar role despite high temperatures favoring volatilization. Unlike boreal forest, the low-latitude forests may reduce the overall lifetime of PCB-153 in China due to enhanced degradation in warmer and moist soils of the tropical and subtropical area. Given that approximately half of the global forests are located in tropical and subtropical regions, they can be important environments influencing the global geochemical cycle and distribution of POPs, hence deserving more scientific attention by modeling and empirical studies.
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http://dx.doi.org/10.1016/j.scitotenv.2021.146285DOI Listing
March 2021

Regional characteristics of atmospheric δS-SO over three parts of Asia monitored by quartz wool-based passive samplers.

Sci Total Environ 2021 Mar 5;778:146107. Epub 2021 Mar 5.

State Key Laboratory of Organic Geochemistry and Guangdong province Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China; Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China.

A new method is presented for measuring atmospheric contents and δS-SO in airborne particulate matter using quartz wool disk passive air samplers (Pas-QW). The ability of Pas-QW samplers to provide time-integrated measurements of atmospheric SO was confirmed in a field calibration study. The average sampling rate of SO measured was 2.3 ± 0.3 m/day, and this was not greatly affected by changes in meteorological parameters. The results of simultaneous sampling campaign showed that the average SO contents in Pakistan and the Indochina Peninsula (ICP) were relatively lower than that of China. The spatial distribution of SO concentrations was largely attributed to the development of the regional economies. The range of δS values observed in Pakistan (4.3 ± 1.4‰) and the ICP (4.5 ± 1.2‰) were relatively small, while a large range of δS values was observed in China (3.9 ± 2.5‰). The regional distribution of sulfur isotope compositions was significantly affected by coal combustion. A source analysis based on a Bayesian mixing model showed that 80.4 ± 13.1% and 19.6 ± 13.1% of artificial sulfur dioxide (SO) sources in China could be attributed to coal combustion and oil combustion, respectively. The two sources differed greatly between regions, and the contribution of oil combustion in cities was higher than previously reported data obtained from emission inventories. This study confirmed that the Pas-QW is a promising tool for simultaneously monitoring atmospheric δS-SO over large regions, and that the results of the isotope models can provide a reference for the compilation of SO emission inventories.
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http://dx.doi.org/10.1016/j.scitotenv.2021.146107DOI Listing
March 2021

Field evaluation of diffusive gradients in thin-film passive samplers for wastewater-based epidemiology.

Sci Total Environ 2021 Jun 30;773:145480. Epub 2021 Jan 30.

State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China; Guangdong Provincial Key Laboratory of Psychoactive Substances Monitoring and Safety, Guangzhou, China. Electronic address:

There is a need for a simple water sampling technique to enable routine monitoring of community drug consumption through wastewater-based epidemiology (WBE). This study investigates the potential use of diffusive gradients in thin films to sample organic compounds (o-DGT) for WBE. Three types of resin gels (HLB, XAD 18, and XDA-1) within o-DGT samplers each were deployed in triplicate at the inlets of two sewage treatment plants of Southern Asian cities. The target compounds included 15 illicit drugs and 18 antibiotics. A comprehensive evaluation was undertaken regarding each resin's ability to accumulate the target compounds and accuracy by comparing active samples. The organic compounds accumulated on each resin gel were characterised at the molecular level using Fourier transform ion-cyclotron-resonance mass spectrometry (FT-ICR MS). The results showed that the HLB resin performed better than the XAD 18 and XDA-1 resins. Based on calculations using the HLB-DGT data, methamphetamine and heroin were the two most popular illicit drugs consumed among the studied populations, and were followed by ketamine and codeine, which agreed well with the authoritative reports and reference data. The total drug consumption in Hanoi was one order of magnitude higher than that in Guangzhou, thus implying a probably more serious drug situation in the former. Overall, the findings of this study demonstrate that o-DGT passive samplers are a promising tool for WBE studies, particularly at WWTPs or in urban streams where an automatic sampler for taking composite water samples is absent.
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http://dx.doi.org/10.1016/j.scitotenv.2021.145480DOI Listing
June 2021

Atmospheric polycyclic aromatic hydrocarbons (PAHs) at urban settings in Pakistan: Spatial variations, sources and health risks.

Chemosphere 2021 Jul 29;274:129811. Epub 2021 Jan 29.

State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.

For the first time, this study presents gaseous and particulate-bound (PM) polycyclic aromatic hydrocarbons (PAHs) in ambient air samples collected from eight major cities of Pakistan. Diurnal air samples (gaseous and PM) were collected in summer 2014 on polyurethane foam and quartz fiber filters using high volume-active air sampler. The US-EPA enlisted 16 priority PAHs in particulate and gaseous phase were measured on gas chromatograph equipped with mass spectrometer detector. The total PAHs concentrations ranged between 188 pg m (in Gilgit), and 2340 pg m (in Lahore). The decreasing order of PAHs concentrations in various cities was in the following order: Lahore > Rawalpindi > Multan > Faisalabad > Karachgi > Peshawar > Quetta > Gilgit. Phenanthrene showed the highest concentration, accounted 18% of total PAHs followed by fluoranthene (12% of total PAHs). This study showed that the gaseous fractions were predominant in the ambient air. Source apportionment analysis revealed that biomass combustion, vehicular emissions and diesel combustion in power generators were the potential PAHs emissions sources. The lifetime lungs cancer risk (LLCR) was in the range of 8.28 × 10 to 2.09 × 10 depicting mild cancer risk to the residents on exposure to atmospheric PAHs. Therefore, it is recommended to monitor atmospheric PAHs throughout the year and also adopt environmentally friendly fuels to reduce PAHs pollution and health risks in the country.
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http://dx.doi.org/10.1016/j.chemosphere.2021.129811DOI Listing
July 2021

Uptake, Acropetal Translocation, and Enantioselectivity of Perfluorooctane Sulfonate in Maize Coexisting with Copper.

J Agric Food Chem 2021 Feb 8;69(7):2062-2068. Epub 2021 Feb 8.

State Key Laboratory of Organic Geochemistry and Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.

Plant uptake and translocation of perfluorooctane sulfonate (PFOS) are critical for food safety and raise major concerns. However, those processes are associated with many undisclosed mechanisms, especially when PFOS coexist with heavy metals. In this study, we investigated the effect of copper (Cu) on PFOS distribution in maize tissues by assessing the PFOS concentration and enantioselectivity. The presence of <100 μmol/L Cu exerted a limited effect on PFOS bioaccumulation, while >100 μmol/L Cu damaged the root cell membrane and increased root permeability, resulting in a higher PFOS concentration in roots. The suppression of acropetal translocation might be attributed to Cu inhibition of carrier proteins. The enantiomer fraction (EF) of 1m-PFOS at <100 μmol/L Cu was higher than that in a commercial product (0.5). Racemic PFOS was detected at >100 μmol/L Cu in roots and the EF variation changed from positive to negative in shoots. These EF results evidenced the existence of a protein-mediated uptake pathway. Besides, this study indicated the challenge of chiral signature application in PFOS source identification, given the effects of heavy metals and plants on PFOS enantioselectivity. The findings provide insight into PFOS bioaccumulation in plants cocontaminated with Cu and will facilitate environmental risk assessment.
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http://dx.doi.org/10.1021/acs.jafc.0c06525DOI Listing
February 2021

Short-term personal PM exposure and change in DNA methylation of imprinted genes: Panel study of healthy young adults in Guangzhou city, China.

Environ Pollut 2021 Apr 28;275:116601. Epub 2021 Jan 28.

State Key Laboratory of Organic Geochemistry and Guangdong Province Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China; Lancaster Environmental Centre, Lancaster University, LA1 4YQ, Lancaster, United Kingdom. Electronic address:

DNA methylation (DNAm) plays a significant role in deleterious health effects inflicted by fine particulate matter (PM) on the human body. Recent studies have reported that DNAm of imprinted control regions (ICRs) in imprinted genes may be a sensitive biomarker of environmental exposure. Less is known about specific biomarkers of imprinted genes after PM exposure. The relationship between PM and its chemical constituents and DNAm of ICRs in imprinted genes after short-term exposure was investigated to determine specific human biomarkers of its adverse health effects. A panel study was carried out in healthy young people in Guangzhou, China. Mixed-effects models were used to evaluate the influence of PM and its constituent exposure on DNAm while controlling for potential confounders. There was no significant correlation between DNAm and personal PM exposure mass. DNAm changes in eight ICRs (L3MBTL1, NNAT, PEG10, GNAS Ex1A, MCTS2, SNURF/SNRPN, IGF2R, and RB1) and a non-imprinted gene (CYP1B1) were significantly associated with PM constituents. Compared to non-imprinted genes, imprinted gene methylation was more susceptible to interference with PM constituent exposure. Among those genes, L3MBTL1 was the most sensitive to personal PM constituent exposure. Moreover, transition metals derived from traffic sources (Cd, Fe, Mn, and Ni) significantly influenced DNAm of the imprinted genes, suggesting the importance of more targeted measures to reduce toxic constituents. Bioinformatics analysis indicated that imprinted genes (RB1) may be correlated with pathways and diseases (non-small cell lung cancer, glioma, and bladder cancer). The present study suggests that screening the imprinted gene for DNAm can be used as a sensitive biomarker of PM exposure. The results will provide data for prevention of PM exposure and a novel perspective on potential mechanisms on an epigenetic level.
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http://dx.doi.org/10.1016/j.envpol.2021.116601DOI Listing
April 2021

Polychlorinated biphenyls in indoor dust from urban dwellings of Lahore, Pakistan: Congener profile, toxicity equivalency, and human health implications.

Indoor Air 2021 Jan 18. Epub 2021 Jan 18.

State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China.

This study is the pioneer assessment of the PCBs in indoor dust particles (from air conditioners) of an urbanized megacity from South Asian. The ∑ PCB concentration ranged from 0.27 to 152.9 ng/g (mean: 24.84 ± 22.10 ng/g). The tri- and tetra-PCBs were dominant homologues, contributing 57.36% of the total PCB concentrations. The mean levels of Σ -dioxin-like (DL), Σ -indicator PCBs and WHO -TEQ for DL-PCBs were 2.22 ± 2.55 ng/g, 9.49 ± 8.04 ng/g and 4.77 ± 4.89 pg/g, respectively. The multiple linear regression indicated a significant correlation of dusting frequency (p = 1.06 × 10-04) and age of the house (p = 1.02 × 10-06) with PCB concentrations in indoor environment. The spatial variation of PCB profile revealed relatively higher concentrations from sites near to illegal waste burning spots, electrical locomotive workshops, and grid stations. Human health risk assessment of PCBs for adults and toddlers through all three exposure routes (ie, inhalation, ingestion, and dermal contact) demonstrated that toddlers were vulnerable to high cancer risk (4.32 × 10 ), while adults were susceptible from low to moderate levels of risk (3.16 × 10 ). Therefore, comprehensive investigations for PCBs in the indoor settings, focusing particularly on the sensitive populations with relationship to the electronic devices, transformers, and illegal waste burning sites, are recommended.
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http://dx.doi.org/10.1111/ina.12788DOI Listing
January 2021

Human Health Risk Assessment by Dietary Intake and Spatial Distribution Pattern of Polybrominated Diphenyl Ethers and Dechloran Plus from Selected Cities of Pakistan.

Int J Environ Res Public Health 2020 12 20;17(24). Epub 2020 Dec 20.

Institute of Chemical, Environmental and Bio Science Engineering, TU Wien, 1060 Vienna, Austria.

A class of intractable bio accumulative halogenated compounds polybrominated diphenyl ethers (PBDEs) was studied. Specifically, PBDEs and dechloran plus (DP) contamination in wheat and the assaulted environment-agricultural soil and dust-from metropolitan cities of Pakistan was the focus. The exposure of brominated flame retardants (BFRs) to humans, their probable toxicological impact on health, source apportionment, and the spatial tendency of BFRs were studied. Chromatographic analysis was performed, and concentrations (ng g) of ΣPBDE and ΣDP in soil, dust, and cereal crops were estimated in a range from 0.63 to 31.70 n.d. to 6.32 and n.d. to 3.47, respectively, and 0.11 to 7.05, n.d. to 4.56 and 0.05 to 4.95, respectively. Data analysis of source apportionment reflected that the existence of solid and e-waste sites, long-range transport, urban and industrial fraction can be the potential source of PBDE and DP pollution. Moreover, potential hazardous risks to human health across the study area via the dietary intake of cereal foods were deemed trifling, and were gauged on the basis of existing toxicological data.
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http://dx.doi.org/10.3390/ijerph17249543DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7766582PMC
December 2020

Shifts in a Phenanthrene-Degrading Microbial Community are Driven by Carbohydrate Metabolism Selection in a Ryegrass Rhizosphere.

Environ Sci Technol 2021 01 28;55(2):962-973. Epub 2020 Dec 28.

State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.

Plants usually promote pollutant bioremediation by several mechanisms including modifying the diversity of functional microbial species. However, conflicting results are reported that root exudates have no effects or negative effects on organic pollutant degradation. In this study, we investigated the roles of ryegrass in phenanthrene degradation in soils using DNA stable isotope probing (SIP) and metagenomics to reveal a potential explanation for conflicting results among phytoremediation studies. Phenanthrene biodegradation efficiency was improved by 8% after 14 days of cultivation. Twelve and ten operational taxonomic units (OTUs) were identified as active phenanthrene degraders in non-rhizosphere and rhizosphere soils, respectively. The active phenanthrene degraders exhibited higher average phylogenetic distances in rhizosphere soils (0.33) than non-rhizosphere soils (0.26). The / values (the ratio of nonsynonymous to synonymous substitutions) were about 10.37% higher in the rhizosphere treatment among >90% of all key carbohydrate metabolism-related genes, implying that ryegrass may be an important driver of microbial community variation in the rhizosphere by relieving the carbohydrate metabolism pressure and improving the survival ability of r-strategy microbes. Most / values of root-exudate-related metabolism genes exhibited little change, except for fumarate hydratase that increased 13-fold in the rhizosphere compared to that in the non-rhizosphere treatment. The / values of less than 50% phenanthrene-degradation-related genes were affected, 30% of which increased and 70% behaved oppositely. Genes with altered / values had a low percentage and followed an inconsistent changing tendency, indicating that phenanthrene and its metabolites are not major factors influencing the active degraders. These results suggested the importance of carbohydrate metabolism, especially fumaric acid, in rhizosphere community shift, and hinted at a new hypothesis that the rhizosphere effect on phenanthrene degradation efficiency depends on the existence of active degraders that have competitive advantages in carbohydrate and fumaric acid metabolism.
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http://dx.doi.org/10.1021/acs.est.0c04951DOI Listing
January 2021

Examination of barnacles' potential to be used as bioindicators of persistent organic pollutants in coastal ecosystem: A Malaysia case study.

Chemosphere 2021 Jan 7;263:128272. Epub 2020 Sep 7.

Institute of Ocean and Earth Sciences, University of Malaya, 50603, Kuala Lumpur, Malaysia; Laboratory of Microbial Ecology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia. Electronic address:

Barnacles are ubiquitous in coastal ecosystems of different geographical regions worldwide. This is the first study attempting to assess the suitability of barnacles as bioindicators of persistent organic pollutants (POPs) in coastal environments. Barnacles were collected from the coasts around Peninsular Malaysia and analyzed for POPs including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and organochlorine pesticides (OCPs). Among POPs, PCBs showed the highest concentrations with elevated contributions of CB28 and CB153. As for PBDEs, BDE47 was the most frequently detected congener, while BDE209 was detected in barnacles from two stations in Port Klang and the levels reached up to >70% of total PBDE concentrations. Concentrations of OCPs detected in barnacles were in the order of CHLs > DDTs > HCHs > HCB and 4,4'-DDE and cis- and trans-chlordane were the predominant OCP compounds. A comparison with previous studies in Malaysia showed consistent levels of POPs. Green mussels collected from selected barnacles' habitats, for the sake of a comparison, showed almost similar profiles but lower concentrations of POPs. The spatial distribution of POPs observed in barnacles and comparison of POP levels and profiles with mussels indicated that barnacles can be useful bioindicators for monitoring POPs contamination in the coastal ecosystems.
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http://dx.doi.org/10.1016/j.chemosphere.2020.128272DOI Listing
January 2021

DNA Methylation Biomarkers of IQ Reduction are Associated with Long-term Lead Exposure in School Aged Children in Southern China.

Environ Sci Technol 2021 01 8;55(1):412-422. Epub 2020 Dec 8.

State Key Laboratory of Organic Geochemistry and Guangdong province Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.

Although lead associated with intelligence decline in children has long been reported, studies combining intelligence determination, molecular mechanisms exploration, and biomarker screen are quite rare. In this study, based on 333 children aged 9-11, we determined the role of DNA methylation (DNAm) in the relationship of lead exposure with children's intelligence. DNAm was measured from children's blood DNA specimens, and mediation analysis was performed to identify DNAm biomarkers mediating the lead-intelligence relationship. We identified forty-three differentially methylated regions (DMRs), and two fragments ( and ) significantly mediated the lead-intelligence relationship, with contribution rates of 30.36% ( = 0.010) and 60.36% ( < 0.001), respectively. In addition, blood lead levels (BLLs) lower than 100 μg/L still adversely affected children's IQs and DNAm of the two fragments. Our data suggests that DNAm mediates lead-associated cognitive delay in children and blood lead reference value for school-aged children (100 μg/L) should be revised, and the candidate biomarkers can be used in related neurological diseases in future.
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http://dx.doi.org/10.1021/acs.est.0c01696DOI Listing
January 2021

Reapportioning the sources of secondary components of PM: A combined application of positive matrix factorization and isotopic evidence.

Sci Total Environ 2021 Apr 11;764:142925. Epub 2020 Oct 11.

State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.

Secondary particles account for a considerable proportion of fine particles (PM) and reasonable reapportioning them to primary sources is critical for designing effective strategies for air quality improvement. This study developed a method which can reapportion secondary sources of PM solved by positive matrix factorization (PMF) to primary sources based on the isotopic signals of nitrate, ammonium and sulfate. Actual PM data in Beijing were used as a case study to assess the feasibility and capacity of this method. In the case, 20 chemical components were used to apportion PM sources and source contributions of nitrate were applied to reapportion secondary source to primary sources. The model performance was also estimated by radiocarbon measurement (C) of organic (OC) and elemental (EC) carbons of eight samples. The PMF apportioned seven sources: the secondary source (36.1%), vehicle exhausts (18.7%), industrial sources (13.6%), biomass burning (11.4%), coal combustion (8.10%), construction dust (7.93%) and fuel oil combustion (4.24%). After the reapportionment of the secondary source, vehicle exhausts (28.7%) contributed the most to PM, followed by biomass burning (25.1%) and industrial sources (18.9%). Fossil oil combustion and coal combustion increased to 8.00% and 11.4%, respectively, and construction dust contributed the least. The average gap between contributions of identified sources to OC and EC and the C measurements decreased 2.5 ± 1.2% after the reapportionment than 13.2 ± 10.8%, indicating the good performance of the developed method.
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http://dx.doi.org/10.1016/j.scitotenv.2020.142925DOI Listing
April 2021

Large-scale biogeographical patterns of antibiotic resistome in the forest soils across China.

J Hazard Mater 2021 02 17;403:123990. Epub 2020 Sep 17.

State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.

Soil is a reservoir of environmental resistomes. Information about their distribution, profiles, and driving forces in undisturbed environments is essential for understanding and managing modern antibiotic resistance genes (ARGs) in human disturbed environments. However, knowledge about the resistomes in pristine soils is limited, particularly at national scale. Here, we conducted a national-scale investigation of soil resistomes in pristine forests across China. Although the antibiotics content was low and ranged from below limit of detection (LOD) to 0.290 μg/kg, numerous detected ARGs conferring resistance to major classes of modern antibiotics were identified and indicated forest soils as a potential source of resistance traits. ARGs ranged from 6.20 × 10 to 2.52 × 10 copies/16S-rRNA and were predominated by those resisting aminoglycoside and encoding deactivation mechanisms. Low abundance of mobile genetic elements (MGEs) and its scarcely positive connections with ARGs suggest the low potential of horizontal gene transfer. The geographic patterns of ARGs and ARG-hosts in pristine forest soils were mainly driven by soil physiochemical variables and followed a distance-decay relationship. This work focusing on pristine soils can provide valuably new information for our understanding of the ARGs in human disturbed environments.
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http://dx.doi.org/10.1016/j.jhazmat.2020.123990DOI Listing
February 2021

Diversity and structure of phenanthrene degrading bacterial communities associated with fungal bioremediation in petroleum contaminated soil.

J Hazard Mater 2021 02 6;403:123895. Epub 2020 Sep 6.

State Key Laboratory of Organic Geochemistry and Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.

Fungal bioremediation is a promising technique for the cleanup of sites contaminated with polycyclic aromatic hydrocarbons (PAHs). However, due to limited understanding of the composition and dynamics of the native PAH-degrading microorganisms in contaminated sites, its application has been difficult. In the present study, DNA stable-isotope probing was performed to identify indigenous phenanthrene (PHE)-degrading bacteria and determine their diversity during the fungal bioremediation process. The results showed a total of 14 operational taxonomic units (OTUs) enriched in the heavy DNA fractions, which were related to seven genera (Sphingomonas, Sphingobacterium, Acidovorax, Massilia, Flavobacterium, Cupriavidus, Aeromicrobium, and unclassified Chitinophagaceae). Along with enhanced efficiency of PHE removal, the number and diversity of indigenous PHE-degrading bacteria in soil bioaugmented with fungi were significantly increased. Furthermore, based on the results of linear model analysis, we found that PHE degraders affiliated with the genus Sphingomonas were significantly enriched during fungal bioremediation. Moreover, fungal bioaugmentation promoted indigenous functional Proteobacteria involved in PAH degradation through co-metabolism, suggesting that PAH biodegradation was attributable to cooperative metabolism by fungi and indigenous bacteria. Our findings provide new insights into the diversity of PHE-degrading communities and support a more comprehensive view of the fungal bioremediation process.
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http://dx.doi.org/10.1016/j.jhazmat.2020.123895DOI Listing
February 2021

Organochlorine pesticides (OCPs) in air-conditioner filter dust of indoor urban setting: Implication for health risk in a developing country.

Indoor Air 2021 May 12;31(3):807-817. Epub 2020 Dec 12.

State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China.

This preliminary investigation highlights the occurrence of organochlorine pesticides (OCPs) in the indoor environment of a megacity, Lahore, Pakistan using the dust ensnared by air-conditioner filters. The Σ OCPs concentration ranged from 7.53 to 1272.87 ng/g with the highest percent contribution by ΣDDT (dichlorodiphenyltrichloroethane; 87.21%) and aldrin (6.58%). The spatial variation of OCPs profile revealed relatively higher concentration from homes near to agricultural and abandoned DDT manufacturing sites. Calculated isomer ratios revealed historic sources of hexachlorocyclohexanes (HCHs) and the fresh input of technical DDT and chlordane by the dwellers. The air conditioner dust was helpful to better understand the health risk in the indoor environment. So far a high lifetime cancer risk (10 ) was predicted for toddlers via accidental ingestion, inhalation, and dermal exposure. Similarly, the non-carcinogenic risk-based hazard quotient was found to be high for toddlers (6.94) and within the permissible limit (<1) for adults.
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http://dx.doi.org/10.1111/ina.12772DOI Listing
May 2021

Insight into the Variability of the Nitrogen Isotope Composition of Vehicular NO in China.

Environ Sci Technol 2020 11 27;54(22):14246-14253. Epub 2020 Oct 27.

State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, P. R. China.

Nitrogen isotope (δN) monitoring is a potentially powerful tool in tracing atmospheric nitrogen oxides (NO); however, the isotopic fingerprint of vehicle exhaust remains poorly interpreted. This deficiency limits our understanding of the origin of atmospheric haze pollution, especially in China. In this study, we systemically explored the δN-NO fingerprints of various vehicle exhausts ( = 137) in China. The δN-NO values of vehicle exhausts ranged from -18.8‰ to +6.4‰, presenting a significant correlation with NO concentrations ( < 0.01). The highest δN-NO values were observed for liquefied petroleum gas vehicles (-0.1 ± 1.8‰), followed by gasoline vehicles (-7.0 ± 4.8‰) and diesel vehicles (-12.7 ± 3.4‰), all of which displayed a rising trend as emissions standards were continuously updated. The δN-NO values under working conditions followed the trend warm start (-5.9 ± 5.0‰) > driving (-7.3 ± 5.9‰) > cold start (-9.2 ± 2.7‰). By establishing a suitable model for assessing representative δN-NO values, the δN-NO values of various vehicles, including different fuel types with different emission standards, were evaluated. A model of δN-NO associated with motor vehicle data was developed, which estimated the national δN-NO value of vehicle emissions to be -12.6 ± 2.2‰, but there was considerable variation among different target areas in China.
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http://dx.doi.org/10.1021/acs.est.0c04749DOI Listing
November 2020

Simultaneous determination of stable chlorine and bromine isotopic ratios for bromochlorinated trihalomethanes using GC-qMS.

Chemosphere 2021 Feb 5;264(Pt 2):128529. Epub 2020 Oct 5.

State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.

Bromochlorinated compounds are organic contaminants originating from different natural and anthropic sources and increasingly found in different environmental compartments. This work presents an online approach for compound specific stable isotope analysis of chlorine and bromine isotope ratios for bromochlorinated trihalomethanes using gas chromatography coupled to quadrupole mass spectrometry (GC-qMS). An evaluation scheme was developed to simultaneously determine stable chlorine and bromine isotope ratios based on the mass spectral data of two target compounds: dibromochloromethane and dichlorobromomethane. The analytical technique was optimized by assessing the impact of different instrumental parameters, including dwell time, split ratios, and ionization energy. Successively, static headspace samples containing the two target compounds at aqueous concentrations ranging from 0.1 mg/L to 5 mg/L were analyzed in order to test the precision and reproducibility of the proposed approach. The results showed a good precision under the optimized instrumental conditions, with relative standard deviations ranging between 0.05% and 0.5% for chlorine and bromine isotope analysis. Finally, the method was tested in a source identification problem in which the simultaneous determination of chlorine and bromine stable isotope ratios allowed the clear distinction of dibromochloromethane from three different manufacturers.
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http://dx.doi.org/10.1016/j.chemosphere.2020.128529DOI Listing
February 2021

The Need to Adopt an International PMT Strategy to Protect Drinking Water Resources.

Environ Sci Technol 2020 10 15;54(19):11651-11653. Epub 2020 Sep 15.

Norwegian Geotechnical Institute (NGI), P.O. Box 3930 Ullevaal Stadion Oslo, N-0806, Norway.

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http://dx.doi.org/10.1021/acs.est.0c04281DOI Listing
October 2020

Distribution and Chiral Signatures of Polychlorinated Biphenyls (PCBs) in Soils and Vegetables around an e-Waste Recycling Site.

J Agric Food Chem 2020 Sep 11;68(39):10542-10549. Epub 2020 Sep 11.

Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.

The distribution and composition of polychlorinated biphenyls (PCBs) within soil-plant systems around a notorious e-waste recycling site were investigated. The average total PCB concentrations in rhizospheric soils (RSs) and nonrhizospheric soils (NRSs) were 2160 and 1270 pg g dry weight (DW), respectively. PCBs were more enriched in RS than NRS for most vegetable species. PCB accumulation in plant tissues varied greatly among plant cultivars, ranging from 4020 to 14 500 pg g DW in shoots and from 471 to 24 400 pg g DW in roots. The compositions of PCBs in soil and plants showed that hexa- and hepta-chlorinated PCBs were preferentially accumulated in soils, while tri- and tetra-PCBs were abundant in plant tissues. These results indicated that low-chlorinated PCBs might be prone to accumulation and transfer within plants, which was confirmed by the relationship between the root concentration factor and octanol-water coefficient. The first eluting enantiomers of PCB 84 and PCB 95 were preferentially transferred between the soil and plants, while the stereoselectivity of PCB 136 varied among plant species. A significant difference in enantiomeric fractionation of PCB 84 between the soil and roots indicated that enantiomeric enhancement of PCB 84 occurred during its translocation from soil to root, whereas no such difference was observed in these chiral PCBs during their translocation from the root to the shoot.
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http://dx.doi.org/10.1021/acs.jafc.0c00479DOI Listing
September 2020

Levels and profiles of persistent organic pollutants in breast milk in China and their potential health risks to breastfed infants: A review.

Sci Total Environ 2021 Jan 29;753:142028. Epub 2020 Aug 29.

State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China. Electronic address:

Although some persistent organic pollutants (POPs) were prohibited or limited in use several decades ago, they are still frequently detected in the human body. The purpose of this study was to understand the levels and profiles of POPs in breast milk in China and assess their potential health risks among breastfed infants under six months of age. A literature review focused on China was performed for studies published from 2001 to 2020. The POP levels in breast milk along with other important variables were extracted, and then the average individual POP levels in breast milk were estimated. This review summarises the distribution of traditional and new POPs, including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), legacy brominated flame retardants (BFRs), perfluorinated compounds (PFCs), and chlorinated paraffins (CPs) and reported notably high levels of short-chain chlorinated paraffins and 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p'-DDE) in breast milk. Although the levels of traditional POPs generally declined over time, especially p,p'-DDE and beta-hexachlorocyclohexane (β-HCH), women living in coastal areas, urban areas, and southern China still have a high body burden of certain POPs. In the present study, the estimated daily intake (EDI) of POPs through breastfeeding was used to evaluate the health risk for infants by comparing with acceptable levels. The findings suggested that infants born in coastal areas most likely suffered potential health risk from exposure to DDT, and the health risk of hexachlorobenzene (HCB) in infants in most nationwide regions remains a concern. More importantly, the EDI of PCBs for infants exceeds the safe limit on a national scale. Continuous surveillance of PCBs in breast milk is critical to evaluate the potential health effects on humans.
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http://dx.doi.org/10.1016/j.scitotenv.2020.142028DOI Listing
January 2021

Summertime stationary waves integrate tropical and extratropical impacts on tropical cyclone activity.

Proc Natl Acad Sci U S A 2020 09 31;117(37):22720-22726. Epub 2020 Aug 31.

Department of Meteorology, University of Hawaii at Manoa, Honolulu, HI 96822.

Tropical cyclones (TC) are one of the most severe storm systems on Earth and cause significant loss of life and property upon landfall in coastal areas. A better understanding of their variability mechanisms will help improve the TC seasonal prediction skill and mitigate the destructive impacts of the storms. Early studies focused primarily on tropical processes in regulating the variability of TC activity, while recent studies suggest also some long-range impacts of extratropical processes, such as lateral transport of dry air and potential vorticity by large-scale waves. Here we show that stationary waves in the Northern Hemisphere integrate tropical and extratropical impacts on TC activity in July through October. In particular, tropical upper-tropospheric troughs (TUTTs), as part of the summertime stationary waves, are associated with the variability of large-scale environmental conditions in the tropical North Atlantic and North Pacific and significantly correlated to the variability of TC activity in these basins. TUTTs are subject to the modulation of diabatic heating in various regions and are the preferred locations for extratropical Rossby wave breaking (RWB). A strong TUTT in a basin is associated with enhanced RWB and tropical-extratropical stirring in that basin, and the resultant changes in the tropical atmospheric conditions modulate TC activity. In addition, the anticorrelation of TUTTs between the North Atlantic and North Pacific makes the TC activity indices over the two basins compensate each other, rendering the global TC activity less variable than otherwise would be the case if TUTTs were independent.
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http://dx.doi.org/10.1073/pnas.2010547117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7502751PMC
September 2020

Biomass burning organic aerosols significantly influence the light absorption properties of polarity-dependent organic compounds in the Pearl River Delta Region, China.

Environ Int 2020 11 28;144:106079. Epub 2020 Aug 28.

State Key Laboratory of Organic Geochemistry and Guangdong province Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.

Atmospheric brown carbon (BrC) is an important constituent of light-absorbing organic aerosols with many unclear issues. Here, the light-absorption properties of BrC with different polarity characteristics at a regional site of Pearl River Delta Region during 2016-2017, influenced by sources and molecular compositions, were revealed using radiocarbon analysis and Fourier transform ion cyclotron resonance mass spectrometry. Humic-like substance (HULIS), middle polar (MP), and low polar (LP) carbon fractions constitute 46 ± 17%, 30 ± 7%, and 7 ± 3% of total absorption coefficient from bulk extracts, respectively. Our results show that the absorption proportions of HULIS and MP to the total BrC absorption are higher than their mass proportions to organic carbon mass, indicating that HULIS and MP are the main light-absorbing components in water-soluble and water-insoluble organic carbon fractions, respectively. With decreases in non-fossil HULIS, MP, and LP carbon fractions (66 ± 2%, 52 ± 2%, and 36 ± 3%, respectively), the abundances of unsaturated compounds and mass absorption efficiency at 365 nm of three fractions decreased synchronously. Increases in both non-fossil carbon and levoglucosan in winter imply that the enhanced light-absorption could be attributed to elevated levels of biomass burning organic aerosols (BBOA), which increases the number of light-absorbing nitrogen-containing compounds. Moreover, the major type of potential BrC in HULIS and MP carbon fractions are oxidized BBOA, but the potential BrC chromophores in LP are mainly associated with primary BBOA. This study reveals that biomass burning has adverse effects on radiative forcing and air quality, and probably indicates the significant influences of atmospheric oxidation reactions on the forms of chromophores.
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http://dx.doi.org/10.1016/j.envint.2020.106079DOI Listing
November 2020