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In this study, we compared the concentrations of the heavy metals Cd, Cr, Cu, Zn, Ni, and Pb in the surface soils of urban parks in Wuhan, Hubei Province with those in the surface soils of urban parks worldwide. The soil contamination data were assessed using enrichment factors, and spatial analysis of heavy metals using inverse distance weighting and quantitative analysis of heavy metal sources with a positive definite matrix factor (PMF) receptor model. Further, a probabilistic health risk assessment of children and adults using Monte Carlo simulation was performed. The average Cd, Cr, Cu, Zn, Ni, and Pb concentrations in the surface soils of urban parks were 2.52, 58.74, 31.39, 186.28, 27.00, and 34.89 mg·kg−1, respectively, which exceeded the average soil background values in Hubei. From the inverse distance spatial interpolation map, heavy metal contamination was primarily observed to be present to the southwest of the main urban area. The PMF model resolved four sources: mixed traffic and industrial emission, natural, agricultural, and traffic sources, with relative contributions of 23.9%, 19.3%, 23.4%, and 33.4%, respectively. The Monte Carlo health risk evaluation model demonstrated negligible noncancer risks for both adult and child populations, whereas the health effects of Cd and Cr on children were a concern for cancer risks.

Wastewater treatment plants (WWTPs) discharge metric tons of microplastics (MPs) daily to aquatic and terrestrial environments worldwide. Herein we provide a holistic review on MPs in the WWTPs, highlighting recent advances in sampling and analysis, improved understanding of their sources, occurrence, and degradation in treatment steps, and the potential risks MPs pose after being discharged in treated effluent and sludge. We discuss the merits and limitations of the various sampling and analytical approaches to determine MPs in major WWTP compartments; highlight new research on MP profiles (abundance, physical characteristics, and compositions) in raw sewage, treated effluent, and waste sludge, which are of particular interest when assessing MP sources, removal rates, and fate; and emphasize mechanisms of MP fragmentation and degradation within WWTPs as well as the potential sorption of wastewater contaminants to the MPs. We find that robust and standardized methods for determining MPs in WWTP samples is still urgently needed, and that complete removal of MPs from wastewater by WWTPs is not guaranteed, although the vast majority of MPs end up in sludge. Areas of research that deserve further attention include the fate of small (20 μm) MPs, abiotic and biotic fragmentation of MPs in the WWTPs, and more empirical data with concentrations on a mass basis.

Precipitation samples were collected in Taiyuan, China, from January 2013 to December 2015. Thirteen elements were detected by inductively coupled plasma-mass spectrometry (ICP-MS). The total concentration of soluble and insoluble materials averaged 9695.26 μg L−1. Si was the most abundant element, accounting for 94.61% of the total, followed by Al and Fe. The wet deposition flux of the 13 elements was 3065.14 mg m−2·yr−1, with the highest flux detected in the summer and the lowest in the spring. The order of deposition flux was as follows: Si > Al > Fe > Zn > Ba > Cu > Mn > Cr > Sr > Pb > Ni > As > Cd. The elements mainly consisted of insoluble materials and accounted for 56.1–98.5% of the total. Per the enrichment factor (EF) results, Zn, Cu, Pb, As, and Cd were derived mainly from anthropogenic activities, while Al and Fe were derived mainly from crustal dusts. Positive Matrix Factorization (PMF) was used to identify 4 sources of soluble materials in 2015. Results revealed that industrial activities were the leading source, contributing to 50.47% of the total, followed by coal combustion (26.09%), vehicle emissions (13.59%), and dusts (9.85%). Combined with 3 years of back trajectory data, southeasterly air masses (with a proportion of 39%) were the main direction from which the precipitation in Taiyuan originated and had a considerable influence on pH and flux.

Printing industry is one of the most important sources of industrial volatile organic compound (VOC) emissions in China, and is thus a key industrial sector in terms of VOC control. However, process-based VOC emission and speciation from the printing industry have not been well identified, mainly owing to the poor emission factors (EFs) and diversity of source profiles. In this study, we systematically characterized process-based VOC emissions from the printing industry for the period of 2010-2019, through the establishment of improved emission factors and composite source profiles. VOC emissions from the printing industry were found to continuously increase from 2010 to 2018, reaching their maximum in 2018 at 939.8 Gg, but started to decrease afterwards. The substantial growth is driven by the large demand for ink and adhesive and the absence of effective control measures in the printing industry. The total VOC emissions and ozone formation potential (OFP) in China in 2019 were 916.1 Gg and 1834.5 Gg, respectively. Gravure printing and the compound process were the processes that contributed the most to both emissions and OFP. Rapidly developing provinces such as Guangdong, Jiangsu, and Zhejiang were the largest contributors to emissions. Oxygenated VOCs (OVOCs) accounted for most of the VOC emissions, followed by alkanes and aromatics, while aromatics were the dominant groups for total OFP, followed by alkenes/alkynes and OVOCs. Ethyl acetate, toluene, isopropanol, isopentane, and n-pentane were the top five VOC species in terms of emissions, while toluene, ethyl acetate, 1,3-butadiene, isopentane, and 1-butene were the top five species in terms of OFP. Scientific and precise control policy were proposed, involving four aspects: environmental access, emission standards, classification and management, and research on source substitution. We believe our study will provide an important reference for the systematic characterization and control policy of VOC emissions from other industries.

Benzene, toluene, ethylbenzene and xylene isomers (BTEX) have raised increasing concern due to their adverse effects on human health. In this study, a coking factory and four communities nearby were selected as the research area. Atmospheric BTEX samples were collected and determined by a preconcentrator GC–MS method. Four biomarkers in the morning urine samples of 174 participants from the communities were measured by LC–MS. The health risks of BTEX exposure via inhalation were estimated. This study aimed to investigate the influence of external BTEX exposure on the internal biomarker levels and quantitatively evaluate the health risk of populations near the coking industry. The results showed that the average total BTEX concentration in residential area was 7.17 ± 7.24 μg m−3. Trans,trans-muconic acid (T,T-MA) was the urinary biomarker with the greatest average level (127 ± 285 μg g−1 crt). Similar spatial trends can be observed between atmospheric benzene concentration and internal biomarker levels. The mean values of the LCR for male and female residents were 2.15 × 10−5 and 2.05 × 10−5, respectively. The results of the risk assessment indicated that special attention was required for the non-occupational residents around the area.

Biomagnification of persistent toxic substances (PTSs) in food chains is of environmental concern, but studies on biotransport of PTSs across aquatic and riparian food chains are still incomplete. In this study, biomagnification of several PTSs including methylmercury (MeHg), polybrominated diphenyl ethers (PBDEs), and 1,2-bis (2,4,6-tribromophenoxy) ethane (BTBPE) was investigated in adjacent aquatic and riparian food webs. Concentrations of MeHg and PBDEs ranged from 2.37 to 353 ng/g dry weight (dw) and not detected (Nd) to 65.1 ng/g lipid weight (lw) in riparian samples, respectively, and ranged from Nd to 705 ng/g dw and Nd to 187 ng/g lw in aquatic samples, respectively. Concentrations of MeHg were significantly correlated with δ

Twelve persistent organic pollutants (POPs) were measured in 11 tissue samples from a pregnant sperm whale stranded on the Huizhou coast of the South China Sea, China, in March 2017. POPs were found to be more concentrated in the irrigated tissues such as placenta, ovary, mammary gland, and liver than the less irrigated tissues such as epidermis. High POP levels detected in the placenta might result in abnormal hormone secretion in the placenta, which would affect the unborn offspring. We hypothesized that ovary is potentially vulnerable to the exposure of higher contaminant levels. The PAH concentrations were higher in the lung than in other tissues, which suggest that PAH levels in the lung were breath-dependent in the sperm whale. The concentrations of POPs except PAHs in the sperm whale blubber were lower than those in the same species in the Northern Hemisphere and were comparable to or lower than those in the same species in the Southern Hemisphere.

Lithium Beam Emission Spectroscopy (Li-BES) diagnostic has been developed on the Experimental Advanced Superconducting Tokamak (EAST), aiming at providing the edge electron density profile and density fluctuation. This system has been upgraded to 32 × 4 (radial × poloidal) channels since the 2016 campaign with a radial observation range of about 30 cm at the midplane on the low field side. The spatial resolution of Li-BES diagnostic is about 1 cm. The whole optical system of Li-BES diagnostic has been shifted 9 cm away from the tokamak axis perpendicular to the flange at horizontal D-port on EAST since the 2017 campaign. It’s confirmed that transmissivities of Avalanche PhotoDiode (APD) channels in the edge region are improved by comparing the relative light intensity calibration factors of the same row of APD channels before and after the shift. Spatial calibration and relative light intensity calibration of this system have been performed. Based on Schweinzer’s algorithm [J. Schweinzer et al., Plasma Phys. Control. Fusion 34, 1173 (1992)], the edge electron density profile is reconstructed and shown to be consistent with those provided by other diagnostics on EAST. The electron density profile evolution during the plasma current ramp-down process is observed with Li-BES diagnostic in both SOL region and pedestal region. With an injected Li-beam under the high frequency chopping control, the temporal resolution of the reconstructed electron density profile can be up to 10 μ s , which reveals temporal behaviors of fast transient events on EAST, such as the L-H transition and ELM crashes.

Short-chain chlorinated paraffins (SCCPs) are a series of new persistent organic pollutants, posing a risk of significant adverse effects to biota. Increasing attention has been paid to SCCP pollution in China as large amounts of chlorinated paraffin (CP) products containing SCCPs have been produced and used there. However, knowledge of the bioaccumulation of SCCPs in marine organisms from the Pearl River Estuary (PRE), Southern China, is still scarce. In this study, SCCP concentrations were measured in seawater, sediments, and marine organisms from the PRE. SCCP concentrations ranged from 180 to 460 ng/L in seawater, from 180 to 620 ng/g dry weight (dw) in sediments, and from 870 to 36,000 ng/g lipid weight (lw) in marine biota samples. C10–11 SCCPs were the predominant homologues in all the samples, with an average abundance of 68% in seawater, 57% in sediments, and 56–77% in marine organisms. However, chlorine patterns of SCCPs in seawater, sediments, and marine organisms were different. Cl8–10 SCCPs dominated in sediments, whereas Cl5–7 SCCPs were the predominant SCCP homologues in water and most organism species. The logarithm bioaccumulation factors (BAFs) of SCCPs ranged from 1.6 to 3.0, and increased significantly with the increase of Kow values for most marine biota species, indicating that Kow was the major factor controlling the bioaccumulation of SCCPs and that SCCPs with higher lipophilicity were more prone to being bioaccumulated from water. Opposite to that observed for log BAFs, biota-sediment accumulation factors of specific SCCPs (range: 0.01–30) decreased significantly with the increase of Kow values. The biomagnification factor of total SCCPs for oyster–mangrove crab was 2.40, implying the potential biomagnification of SCCPs for benthos in the PRE.

Developing cleaner and affordable alternatives to the sole reliance on fossil fuels has intensified efforts to improve the thermochemical conversion property of the second-generation lignocellulosic biomass. This study aimed to explore the effects of the two torrefaction temperatures (200 and 300 °C), the two reaction atmospheres (N2/O2 and CO2/O2), and the three heating rates (5, 10, and 15 °C/min) on the combustion regime of water hyacinth (WH). Decomposition behaviors, reaction kinetics, thermodynamics, and mechanisms, evolved emissions and functional groups, and fuel microstructure properties were quantified. The deoxygenation and dehydration reactions acted as the main drivers of the torrefaction process, with the peak degree of deoxygenation of 86.21% for WH torrefied at 300 °C (WH300). WH300 significantly reduced the quantity of oxygen-containing functional groups and altered the fuel microstructure properties. The order of the decomposition rates of the pseudo-components were hemicellulose > cellulose > lignin for both WH and WH torrefied at 200 °C (WH200) and cellulose > lignin > hemicellulose for WH300. The average activation energy fell from 197.71 to 195.71 kJ/mol for WH, 287.90 to 195.97 kJ/mol for WH200, and 226.92 to 184.94 kJ/mol for WH300 when the atmosphere changed from N2/O2 to CO2/O2. The heating rate exerted a stronger control on their combustion behaviors than did the reaction atmosphere. CO2, NO, and NO2 emissions dropped by 46.0, 53.1, and 65.9% for WH200 and 29.6, 42.8, and 62.5% for WH300, respectively, when compared to WH. 473.7 °C, 5 °C/min, and the CO2/O2 atmosphere were the optimal settings for the maximized combustion efficiency. 717.1 °C was determined as the optimal setting for the minimized combustion emissions. Our study can yield new insights into the large-scale and cleaner combustion of the torrefied water hyacinth.

Objective: To examine the role of total mercury (T-Hg) in placenta as a biomarker of prenatal mercury (Hg) exposure and determine the association between prenatal Hg exposure and risk for neural tube defects (NTDs) in offspring. Methods: Total Hg concentrations in placental tissue were detected in 408 NTD cases and 593 healthy controls enrolled in Shanxi province in northern China. Methylmercury (MeHg) and T-Hg were also detected in the umbilical cord of 147 NTD cases and 140 healthy controls. In addition, MeHg and T-Hg were detected in fetal kidney, liver, and brain tissues of 51 NTD cases. Spearman’s rank correlation (rs) was used to evaluate the correlations between placental T-Hg and T-Hg in umbilical cord and fetal kidney, liver, and brain tissues. The Wilcoxon rank-sum test was used to compare T-Hg amounts between case and control groups. Logistic regression was used to examine the association between placental T-Hg and risk for NTDs. Results: Placental T-Hg was significantly correlated with T-Hg in umbilical cord (rs = 0.479), kidney (rs = 0.718), liver (rs = 0.656), and brain (rs = 0.512) tissues (all p

The quality of urban soil is closely related to the safety of public places and the guarantee of food quality. This study investigated the level, distribution, source, and carcinogenic risk of 16 U.S. EPA (Environmental Protection Agency) priority polycyclic aromatic hydrocarbons (PAHs) in urban, agricultural, and montane soil in Taiyuan. The &sum, 16PAHs level varied from 104.78 to 6594.63 ng g&minus, 1 with a mean of 922.93 ng g&minus, 1, and 47.73% of the soil samples were severely contaminated, with a concentration higher than 600 ng g&minus, 1. PAHs with higher molecular weight (&ge, 4 rings) were dominant in PAHs profiles accounting for 80.92%. In the spatial distribution of PAHs, hotspots of &sum, 16 PAHs were observed near the industries, indicating pollutants emitted by the industries directly affect the surrounding soil quality. The sources identified by positive matrix factorization (PMF) indicated: coal combustion (40.77%), vehicle exhausts (32.94%), biomass combustion (14.89%), and coking source (11.40%). Coal-related sources (coal and coking sources) were the major contributors (52.17%) to PAHs and carcinogenic risk (46.48%) assessed by BaP toxic equivalent concentration in total soils. Therefore, the extensive usage of coal was the leading factor for PAH pollution and health risk in Taiyuan soil.

There is little information about the residue levels and congener composition of organic contaminants (OCs) in cetaceans. In the present study, we investigated the polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in the blubber, blood, brain and testes of Indo-Pacific humpback dolphins (Sousa chinensis) stranded in the Pearl River Estuary (PRE), China. The lowest blubber/tissue partition coefficients were found for sum hexachlorocyclohexanes (ΣHCHs) and ΣPAHs, while the highest were in ΣPCBs and sum dichlorodiphenyltrichloroethanes (ΣDDTs), likely attributing to the octanol-water partition features. The low levels of OCs in brain and testes theoretically resulted from the blood-brain barrier, blood-testes barrier, contaminant molecule dimensions and unique lipid compositions in the brain and testes. Compared with other contaminants, the higher mean brain/blood and testes/blood partition coefficients found for mirex, heptachlor, dieldrin and endrin would increase the risks associated with exposure-related toxicity and the bioavailability of contaminants within these tissues. Observations also suggest that as lipid mobilizes from blubber, contaminants may redistribute, leading to elevated tissue (such as brain) concentrations. Therefore, dolphins with less blubber may be more susceptible to health risks. The Indo-Pacific humpback dolphins living in PRE are at great risk due to variety of OCs in indirect contact with non-target organisms, affecting the health of animals (toxic effects and accumulation). Our findings contribute to the knowledge of the potential effects of OCs exposure on developmental neurotoxicity and reproductive damage in marine mammals.

H-modes induced by sawtooth events can be often observed in discharges with marginal auxiliary power injection in EAST. Poloidal flow shear at the very plasma edge, increasing ∼25% up to the threshold value, is observed just before the L-H transition by means of a fast reciprocating probe array in EAST. This suddenly risen poloidal flow shear, caused by the increased turbulent driven Reynolds force, is motived by the heat pulse originally released by a sawtooth crash at the plasma core. Associated with the critical poloidal flow shear, the local turbulent decorrelation rate increases significantly. The increased turbulent decorrelation rate compensated by nonlinear energy transfer rate from the turbulence to the low-frequency shear flows, exceeding the turbulence energy input rate, is sustained for several hundred microseconds till the turbulence quench happening.

Emissions (particularly aromatic compounds) from coal industries and biomass fuels combustion lead to high health risks for neighboring residents. To investigate the association of polycyclic aromatic hydrocarbons (PAHs) and benzene, toluene, ethylbenzene and 1,2-dimethylbenzene (BTEX) exposure with lung function and respiratory symptoms among adults and children near the coal-chemical industry in Northern China, adults and children from a county dotted with coal chemical industry were chosen as subjects for investigation (investigated area, IR). The control group consisted of adults and children from an agricultural county (control area, CR). The environmental and urinary PAH and BTEX levels of adults and children were determined by isotope dilution liquid chromatography coupled with tandem mass spectrometry. The Mann-Whitney U test and multivariate linear regression models were used to analyze the relationship between pollutant exposure and the respiratory system. The results showed that in an ambient environment, levels of PAHs and BTEX in the IR were significantly higher than those in the CR. Particularly, the concentration profiles for air samples were IR > CR and indoor > outdoor. Both for adults and children, the geometric (GM) concentrations of urinary PAHs and BTEX from the IR were significantly higher than those measured in the CR. Additionally, the urinary PAH exposure level profiles of smokers were higher than those of nonsmokers, indicating that indoor air and smoking were both important nonoccupational exposure sources. The decline of the forced expiratory in the first second (FEV1, %) and the forced expiratory middle flow rate (FEF25%) in children were associated with increasing urinary PAH metabolite levels (p

For human health benefits it is crucial to see if carcinogenic air pollutants like polycyclic aromatic hydrocarbons (PAHs) are reduced accordingly along with the control of the criteria pollutants including fine particles (PM2.5). A number of studies documented that enhanced temporary emission control during the 2014 Asia-Pacific Economic Cooperation summit (APEC) in Beijing resulted in substantial drops of observed ambient PM2.5, as well as PAHs, in urban areas of Beijing, yet it is not clear whether PM2.5-bound PAHs in the rural areas were also lowered during the APEC. Here filter-based PM2.5 samples were collected at a rural site in northeast of Beijing, and analyzed for 25 PAHs before (Oct. 27-Nov. 2, 2014), during (Nov. 3–12, 2014) and after (Nov. 13, 2014–Jan. 14, 2015) the APEC. Observed concentrations of PM2.5, OC and EC during the APEC dropped by about 30%, however, average PM2.5-bound PAHs and their incremental lifetime cancer risk (ILCR), 25.65 ng/m3 and 3.2 × 10−4, remained almost unchanged when compared to that of 25.48 ng/m3 and 3.5 × 10−4, respectively, before the APEC. After the APEC with the start of wintertime central heating in urban Beijing on Nov. 15, 2014, average total concentration of PAHs and their ILCR highly elevated and reached 118.25 ng/m3 and 1.5 × 10−3, respectively. Source apportioning by positive matrix factorization (PMF) revealed that coal combustion was the largest source that contributed 63.2% (16.1 ng/m3), 78.5% (20.1 ng/m3) and 56.1% (66.3 ng/m3) to the total PAHs before, during and after the APEC, respectively. Uncontrolled residential coal use during the APEC was found to be the reason for unabated levels of PAHs, and the largely aggravated PAHs after the APEC was resulted from increased coal consumption for wintertime residential heating. Our results suggested reducing emission from residential coal combustion is crucial to mitigate carcinogenic PAHs in ambient air, especially in rural areas.

A newly developed radial directional electron probe (DEP) has been applied to the unidirectional electron current measurement on EAST tokamak. The DEP consists of two radial arrays of channels which have opposite directions and align along the local magnetic field line. Each radial array has 6 holes with a radial interval of 5 mm. Every channel has a hole with 0.5 mm radial width, 3 mm depth and 15° poloidal opening angle. The graphite collector embedded inside the hole is biased to positive potential to repel low energy ions, and high energy ions are blocked by the hole surface because their Larmor radii are larger than the radial width of hole. In consequence, the ion current collected by the DEP collector can be ignored in contrast with the electron current, as demonstrated by the I-V characteristics in a DEP commissioning experiment. The difference of collected current between two opposite channels signifies the unidirectional electron current in the flux tube. In a lower hybrid wave (LHW) modulation experiment, the amplitude and radial structure of unidirectional electron current induced by LHW is measured directly by this radial DEP array, and the LHW filament current covers over 20 mm radial region with a maximum of 20 A/cm2.

SiOx/NiCr coatings with different SiOx thicknesses were deposited by the combination of ion implantation (IIP), filter cathode vacuum arc (FCVA), and electron beam (E-beam) evaporation methods to protect flexible Kapton from atomic oxygen (AO) attack. Due to the ion stitching effect and mechanical interlocking of implanted Ni+, the ductility and supporting effect of the fcc γ (Ni-Cr) alloy layer, and the low growth stress of the SiOx, the SiOx/NiCr coatings showed high adhesion and toughness. Exposure tests indicated that the AO erosion yield of the 1 μm-thick SiOx/NiCr-coated Kapton was 5.6 × 10−26 cm3 atom−1, which was attributed to the formation of a compact and continuous thin SiO2 layer. In addition, the inherent kinetic energy and oxidation performance dissipation of AO on the thick inner walls of cracks helped to reduce the cavity cross-sectional area and maximum width in the matrix.

Textile dyeing sludge (TDS) is a highly toxic solid waste whose co-pyrolysis can jointly achieve waste reduction and recovery of value-added products. This study aimed to fill the knowledge gaps about the co-pyrolysis mechanisms and products (gases and solids) and their dynamics in response to the atmosphere type, blend ratio, heating rate, temperature, and their interactions. The high temperature pyrolysis (>720 °C) in the CO2 atmosphere appeared as the best option for the waste reduction. The (co-)pyrolysis in the CO2 atmosphere enhanced S-containing air pollutants, CO, and CH4 but reduced NOx. The interaction effect between TDS and durian shell (DS) residues promoted the productions of furan and acid compounds and inhibited the productions of aromatic, phenolic, and N-containing compounds. The atmosphere type affected the type and strength of the reactions involved in the production of biochars. Our findings provide practical and new insights into the optimization of energy generation, product recovery, and emission control during the (co-)pyrolysis.

In response to the global initiative for greenhouse gas emission reduction, the co-combustion of coal and spent pot lining (SPL) may cost-effectively minimize waste streams and environmental risks. This study aimed to quantify the emission-to-ash detoxification mechanisms of the co-combustion of SPL and pulverized coal (PC) and their kinetics, gas emission, fluorine-leaching toxicity, mineral phases, and migrations. The main reaction covered the ranges of 335–540 °C and 540–870 °C while the interactions occurred at 360–780 °C. The apparent activation energy minimized (66.99 kJ/mol) with 90% PC addition. The rising PC fraction weakened the peak intensity of NaF and strengthened that of Ca2F, NaAlSiO4, and NaAlSi2O6. The addition of PC enhanced the combustion efficiency of SPL and raised the melting temperature by capturing Na. PC exhibited a positive effect on solidifying water-soluble fluorine and stabilizing alkali and alkaline earth metals. The leaching fluorine concentrations of the co-combustion ashes were lower than did SPL mono-combustion. The main gases emitted were HF, NH3, NOx, CO, and CO2. HF was largely released at above 800 °C. Multivariate Gaussian process model-based optimization of the operational conditions also verified the gas emissions results. Our study synchronizes the utilization and detoxification of SPL though co-combustion and provides insights into an eco-friendlier life-cycle control on the waste-to-energy conversion.

Mine-polluted wastewater with mercury (Hg) poses severe environmental pollution since Hg(II) can be converted to highly neurotoxic methylmercury (MeHg) under anaerobic conditions. Previous studies on Hg methylation have focused on aquatic sediments, but few have investigated the MeHg formation in water layers containing algae. In this study, we investigated the dynamic effect of algae on Hg methylation throughout the lifetime of algae. We found that Chlorella pyrenoidosa was a non-methylating alga and exhibited good tolerance to Hg stress (1–20 μg/L); thus Hg(II) could not inhibit the process of eutrophication. However, the presence of C. pyrenoidosa significantly enhanced the Hg methylation by Geobacter sulfurreducens PCA. Compared to the control sample without algae, the MeHg production rate of algae-bacteria samples remarkably exacerbated by 62.3–188.3% with the algal growth period at cell densities of 1.5 × 106–25 × 106 cells/mL. The increase of algal organic matter and thiols with the algal growth period resulted in the exacerbation of MeHg production. The Hg methylation was also enhanced with the presence of dead algae, of which the enhancement was ~62.4% lower than that with the presence of live algae. Accordingly, the potential mechanism of Hg methylation in a freshwater algae-bacteria symbiotic system throughout the algal lifetime was proposed.

The divertor Langmuir probes (Div-LPs) system is a key diagnostic for measuring divertor plasma parameters in tokamaks. The accuracy of the measurement is the basis of physical researches. However, the excessive heat load on the target plates may lead to serious ablation of graphite probe tips, especially during long-pulse operation or unmitigated disruptions. In order to evaluate the data uncertainty caused by ablation, a statistical study has been made based on the Ohmic discharges in the EAST (Experimental Advanced Superconducting Tokamak) 2018 experiment campaign. The results show that for the discharges with the same plasma parameters, the peak particle flux of upper outer divertor measured by Div-LPs becomes several times smaller as the discharge progresses in a long experimental campaign, which is mainly due to that the effective collection area of the ablated probe tip becomes smaller and smaller. To quantitatively calculate the decrease of the effective area of the probe tip, the physical quantity of accumulated injection energy is introduced. A simple model is proposed and used to characterize the relationship between the effective collection area and the total accumulated injection energy. In addition, arbitrary H-mode discharges are selected to verify the model. By comparing the calibrated data of Div-LPs with other diagnostics, it is found that the model is also suitable for H-mode discharges with the strike point near the frequently-used-SP, and thereby the uncertainty after calibration is significantly reduced. In the future, the method will be employed for Div-LPs data processing near the strike point on EAST, which will facilitate further researches on divertor physics.

Atmospheric dry deposition is a major pathway of pollutants removal from the atmosphere to the water and soil ecosystem. Polycyclic aromatic hydrocarbons (PAHs) in Taiyuan, China, are one class of the most hazardous air pollutants due to the high emission intensity from coal consumption. To better understand the PAHs removing from the atmosphere, 16 USEPA priority PAHs (except for naphthalene) in the particle dry deposition samples were detected from August 2013 to November 2014 at an urban site in Taiyuan. Dry deposition fluxes of particles were estimated as 157.44–358.17 mg/(m 2 ·d), with the highest value in spring and lowest in autumn. Particle dry deposition fluxes of ∑15-PAHs ranged from 2436.20 to 14,967.36 ng/(m 2 ·d), and was the highest in winter and lowest in summer. Higher PAHs particle dry deposition fluxes were related to higher PAHs emission, lower air temperature, less precipitation as well as wind speed. Overall dry deposition velocities of 15-PAHs were 0.056 ± 0.027 cm/s in winter and 0.42 ± 0.050 cm/s in summer, respectively, and high molecular weight PAHs showed low dry deposition velocities. Positive matrix factorization model's results indicated that coking, vehicle exhaust, coal combustion were the primary PAHs sources in particle dry deposition samples, accounting for 18.64%, 26.54% and 54.82% of total PAHs, respectively. The toxic equivalent concentrations (BaPeq) of ∑15-PAHs in particle dry deposition samples was in the range of 0.69–2.94 μg/g, which might be a good explanation to high soil PAHs concentrations reported in Shanxi province, China. Furthermore, this work could prove the significance of coal combustion, and related pollution control works are needed to conduct to alleviate the PAHs pollution situation.

Atmospheric transport of black carbon (BC) from surrounding areas has been shown to impact the Tibetan environment, and clarifying the geographical source and receptor regions is crucial for providing guidance for mitigation actions. In this study, 10 trace volatile organic compounds (VOCs) sampled across Tibet are chosen as proxies to diagnose source regions and related transport of pollutants to Tibet. The levels of these VOCs in Tibet are higher than those in the Arctic and Antarctic regions but much lower than those observed at many remote and background sites in Asia. The highest VOC level is observed in the eastern region, followed by the southern region and the northern region. A positive matrix factorization (PMF) model found that three factors—industry, biomass burning, and traffic—present different spatial distributions, which indicates that different zones of Tibet are influenced by different VOC sources. The average age of the air masses in the northern and eastern regions is estimated to be 3.5 and 2.8 days using the ratio of toluene to benzene, respectively, which indicates the foreign transport of VOC species to those regions. Back-trajectory analyses show that the Afghanistan-Pakistan-Tajikistan region, Indo-Gangetic Plain (IGP), and Meghalaya-Myanmar region could transport industrial VOCs to different zones of Tibet from west to east. The agricultural bases in northern India could transport biomass burning-related VOCs to the middle-northern and eastern zones of Tibet. High traffic along the unique national roads in Tibet is associated with emissions from local sources and neighboring areas. Our study proposes international joint-control efforts and targeted actions to mitigate the climatic changes and effects associated with VOCs in Tibet, which is a climate sensitive region and an important source of global water.

Long-range transport followed by deposition of black carbon on glaciers of Tibet is one of the key issues of climate research as it induces changes on radiative forcing and subsequently impacting the melting of glaciers. The transport mechanism, however, is not well understood. In this study, we use short-lived reactive aromatics as proxies to diagnose transport of pollutants to Tibet. In situ observations of short-lived reactive aromatics across the Tibetan Plateau are analyzed using a regional chemistry and transport model. The model performance using the current emission inventories over the region is poor due to problems in the inventories and model transport. Top-down emissions constrained by satellite observations of glyoxal are a factor of 2–6 higher than the a priori emissions over the industrialized Indo-Gangetic Plain. Using the top-down emissions, agreement between model simulations and surface observations of aromatics improves. We find enhancements of reactive aromatics over Tibet by a factor of 6 on average due to rapid transport from India and nearby regions during the presence of a high-altitude cut-off low system. Our results suggest that the cut-off low system is a major pathway for long-range transport of pollutants such as black carbon. The modeling analysis reveals that even the state-of-the-science high-resolution reanalysis cannot simulate this cut-off low system accurately, which probably explains in part the underestimation of black carbon deposition over Tibet in previous modeling studies. Another model deficiency of underestimating pollution transport from the south is due to the complexity of terrain, leading to enhanced transport. It is therefore challenging for coarse-resolution global climate models to properly represent the effects of long-range transport of pollutants on the Tibetan environment and the subsequent consequence for regional climate forcing.

Because of mountain cold-trapping, the soil in the Tibetan Plateau may be an important global sink of organochlorine pesticides (OCPs). However, there are limited data on OCPs in the soils of the Tibetan Plateau. In addition, the atmospheric transport and deposition mechanisms of OCPs also need to be further studied. In this study, the sampling area covered most regions of the Tibetan Plateau. The detection frequencies of ΣChlordane (sum of trans-chlordane, cis-chlordane and oxychlordane), HCB, ΣNonachlor (sum of trans- and cis-nonachlor), DDTs, ΣEndo (sum of endosulfan-I, endosulfan-II and endosulfate), aldrin, HCHs, ΣHeptachlor (sum of heptachlor and heptachlor epoxide), mirex and dieldrin were 100%, 98.3%, 96.6%, 94.8%, 89.7%, 87.9%, 62.1%, 55.2%, 32.8% and 6.9%, respectively. DDTs (with arithmetic mean values of 1050ngkg-1 dw) and HCHs (393ngkg-1) were the principal OCPs in cultivated soils, whereas ΣEndo (192ngkg-1) and ΣChlordane (152ngkg-1) were the principal OCPs in non-cultivated soils. Local use of DDTs, dicofol and HCHs may be an important source of OCP accumulation in the soil of the Tibetan Plateau. Aldrin and endosulfan are considered to be good indicators for studying atmospheric transport and deposition of OCPs from South Asia and Southeast Asia. Two zones with high OCP levels were found in the southeast and northwest of the Tibetan Plateau. The zones have dissimilar pollution sources of OCPs and are influenced by different factors that affect their precipitation scavenging efficiency. The amount of precipitation was the dominant factor in the southeast, whereas large differences in temperature and wind speed were the dominant factors in the northwest.

Municipal wastewater treatment plants (MWTPs) serve an essential role in reducing mercury (Hg) pollution. However, few studies quantified the transport and transformation of Hg through MWTPs, particularly plants based on the anaerobic-anoxic-aerobic (A

The risk associated with human exposure to short-chain chlorinated paraffins (SCCPs) via dietary intake are of great concern because of the bioaccumulation potential of SCCPs in biota and adverse effects. Fish are an important food source for human beings. However, there is a paucity of studies on human exposure to SCCPs via fish consumption. In this study, SCCPs were measured in frequently consumed river fish from the Pearl River Delta, and farmed freshwater fish and wild sea fish from the Yangtze River Delta. Lipid-normalized SCCP levels in river fish ranged from 3000 to 41,000 ng/g lipid weight (lw), with an average of 16,000 ± 12,000 ng/g lw. SCCP concentrations in farmed fish were significantly lower than those in river fish (p 0.05), but significantly higher than those in sea fish (p 0.05). Homologue patterns of SCCPs in river fish, farmed fish and sea fish were similar, with C

To grasp the key factors affecting particle mass scattering efficiency (MSE), particle mass and number size distribution, bulk PM2.5 and PM10 and their major chemical compositions, and particle scattering coefficient (bsp) under dry condition were measured at an urban site in Guangzhou, south China during 2015–2016. On annual average, 10 ± 2 %, 48 ± 7 % and 42 ± 8 % of PM10 mass were in the condensation, droplet and coarse modes, with mass median aerodynamic diameters (MMADs) of 0.21 ± 0.00, 0.78 ± 0.07 and 4.57 ± 0.42 μm, respectively. The identified chemical species mass concentrations can explain 79 ± 3 %, 82 ± 6 % and 57 ± 6 % of the total particle mass in the condensation, droplet and coarse mode, respectively. Organic matter (OM) and elemental carbon (EC) in the condensation mode, OM, (NH4)2SO4, NH4NO3 and crustal element oxides in the droplet mode, and crustal element oxides, OM and CaSO4 in the coarse mode were the dominant chemical species in their respective modes. The measured bsp can be reconstructed to the level of 91 ± 10 % using Mie theory with input of the estimated chemically-resolved number concentrations of NaCl, NaNO3, Na2SO4, NH4NO3, (NH4)2SO4, K2SO4, CaSO4, Ca(NO3)2, OM, EC, crustal element oxides and unidentified fraction. MSEs of bulk particle and individual chemical species were underestimated by less than 13 % in any season based on the estimated bsp and chemical species mass concentrations. Seasonal average MSEs varied in a small range of 3.5 ± 0.1 to 3.9 ± 0.2 m2 g−1 for fine particles, which was mainly caused by seasonal variations of the mass fractions and MSEs of OM in the droplet mode.

This study aimed to evaluate internal biomarkers and external estimation of exposure to polycyclic aromatic hydrocarbons (PAH) in a high cancer mortality area in southeast China and identify which of these showed a stronger association of PAH with cancer mortality. A retrospective death survey was conducted to determine the mortality rate of cancer. Cumulative and aggregate external exposures to PAHs of local residents were estimated by field sampling. Three regions in southwest China with gradient PAH exposure levels from high to low (H, M, and L) were selected in this study. Research participants were selected from these three regions using a statistical sampling method. To determine the internal exposure, urinary OH-PAHs were measured using the first morning urine samples. From the retrospective death survey, the highest age-standardized lung cancer mortality rate occurred in Region H (78 per 100,000 person-years), followed by that in Regions M (33 per 100,000 person-years) and L (15 per 100,000 person-years), and the rate was nearly four times China's national mortality rate (20 per 100,000 person-years). Residents estimated daily aggregate exposure doses per unit body weight to carcinogenic benzo(a)pyrene equivalent concentration were 159 ± 14 ng-kg−1-day−1, 7.41 ± 2.76 ng-kg−1-day−1, and 6.13 ± 2.89 ng-kg−1-day−1 in Region H, M, and L, respectively. The participants in Region M had the greatest urinary OH-PAH concentration (9.10 ± 4.92 μg-g−1 crt), followed by Region H (8.01 ± 4.22 μg-g−1 crt) and L (7.12 ± 3.10 μg-g−1 crt). The spatial difference in the total OH-PAHs was not statistically significant. Aggregate and cumulative exposure to 16 PAHs from external routes were found, and external exposure had a stringer relationship with lung cancer mortality than internal exposure.

A series of H-mode discharges have been conducted in the EAST tokamak to study the effect of divertor closure on divertor neutral distribution and edge plasmas by scanning the location of the outer strike point. When the outer strike point moves close to the corner within ∼ 4.5 cm , the gauge in upper sub-divertor shows that the neutral pressure increases, and the reciprocating probe at outer mid-plane indicates that electron temperature decreases and electron density increases in the scrape-off layer (SOL). In the meantime, the tungsten impurity concentration and radiation power in the main plasma decrease remarkably, while the main plasma density and stored energy increase slightly. SOLPS-ITER simulation without particle drifts is performed to better understand the impact of divertor closure. The simulation clearly demonstrates that a more closed divertor produces more neutrals around the corner with the increase of electron density and the decrease of electron temperature in the SOL, consistent with experimental results. Furthermore, more neutrals escape the divertor region and penetrate into the pedestal region, which induces more pedestal fuelling, increasing pedestal electron density. EAST will upgrade the lower divertor with a more closed geometry. These results provide important guidance for the upcoming upgrade.

A total of seventy surface sediments were collected from fourteen estuaries of South China to investigate the distribution of polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), 1,2-bis (2,4,6-tribromophenoxy) ethane (BTBPE) and dechlorane plus (DP). The concentrations of Σ16PBDEs, DBDPE, BTBPE and DP in estuarine sediments ranged from 0.39 to 81.2, 0.18 to 49.9, not detected to 0.62, and 0.025 to 1.66 ng/g dry weight, respectively. Significant differences for levels of Σ16PBDEs, DBDPE, BTBPE and DP were found among the sediments from fourteen estuaries. Sediments from the Pearl River Estuary had the highest concentrations of Σ16PBDEs, DBDPE and DP. PBDEs and DBDPE were the main halogenated flame retardants in estuarine sediments. BDE 209 was predominant congener of PBDEs with an average contribution of 88.1% to the total PBDEs. 32.9% sediment samples from South China had fanti values lower than 0.65, suggesting that stereoselective enrichment of syn-DP occurred in estuarine sediments.

Architectural decoration is one of the most important sources of anthropogenic volatile organic compound (VOC) emissions in China, as well as one of the major sources of indoor air pollution, which negatively affects the comfort, health, and productivity of residents. In this study, a VOC emission inventory of architectural coatings and adhesives for new buildings in China in 2017 was developed based on building area, using a new database established through a bottom-up activity level investigation and analysis of large number of samples. Our results show that the investigated coating ratio of exterior walls distinctly differed from the empirical value. The comprehensive VOC emission factors and total emissions for architectural coatings and adhesives in China in 2017 were 214.5 kg km−2 and 614 kt, respectively, with floor coatings (41.1%) and solvent-based adhesives (18.2%) being the highest contributors to emissions. Shandong, Jiangsu, Zhejiang, Sichuan, and Guangdong were the five largest emission contributors, accounting for 39.1% of VOC emissions from architectural coatings and adhesives for new buildings. Market access and supervision of architectural materials should be strengthened maximally, and gradual phasing out of solvent-based coatings and adhesives is advised in the future in China.

The quantile regression (QR) method has been increasingly introduced to atmospheric environmental studies to explore the non-linear relationship between local meteorological conditions and ozone mixing ratios. In this study, we applied QR for the first time, together with multiple linear regression (MLR), to analyze the dominant meteorological parameters influencing the mean, 10th percentile, 90th percentile and 99th percentile of maximum daily 8-h average (MDA8) ozone concentrations in 2000–2015 in Hong Kong. The dominance analysis (DA) was used to assess the relative importance of meteorological variables in the regression models. Results showed that the MLR models worked better at suburban and rural sites than at urban sites, and worked better in winter than in summer. QR models performed better in summer for 99th and 90th percentiles and performed better in autumn and winter for 10th percentile. And QR models also performed better in suburban and rural areas for 10th percentile. The top 3 dominant variables associated with MDA8 ozone concentrations, changing with seasons and regions, were frequently associated with the six meteorological parameters: boundary layer height, humidity, wind direction, surface solar radiation, total cloud cover and sea level pressure. Temperature rarely became a significant variable in any season, which could partly explain the peak of monthly average ozone concentrations in October in Hong Kong. And we found the effect of solar radiation would be enhanced during extremely ozone pollution episodes (i.e., the 99th percentile). Finally, meteorological effects on MDA8 ozone had no significant changes before and after the 2010 Asian Games.

Concentrations of gaseous elemental mercury (GEM) were continuously monitored from May 2011 to May 2012 at the Wuzhishan State Atmosphere Background Monitoring Station (109°29′30.2″ E, 18°50′11.0″ N) located in Hainan Island. This station is an ideal site for monitoring long-range transport of atmospheric pollutants from mainland China and Southeast Asia to South China Sea. Annual average GEM concentration was 1.58 ± 0.71 ng m−3 during the monitoring period, which was close to background values in the Northern Hemisphere. GEM concentrations showed a clear seasonal variation with relatively higher levels in autumn (1.86 ± 0.55 ng m−3) and winter (1.80 ± 0.62 ng m−3) and lower levels in spring (1.16 ± 0.45 ng m−3) and summer (1.43 ± 0.46 ng m−3). Long-range atmospheric transport dominated by monsoons was a dominant factor influencing the seasonal variations of GEM. The GEM diel trends were related to the wind speed and long-range atmospheric mercury transport. We observed 30 pollution episodes throughout the monitoring period. The analysis of wind direction and backward trajectory suggested that elevated GEM concentrations at the monitoring site were primarily related to the outflows of atmospheric Hg from mainland China and the Indochina peninsula. The △GEM/△CO values also suggested that GEM was significantly affected by the long-range transport from the anthropogenic sources and biomass burning in Asia and Indochina peninsula.

Short-chain chlorinated paraffins (SCCPs) are candidate persistent organic pollutants (POPs) that are under review by the Stockholm Convention. China is currently the largest producer and consumer of chlorinated paraffins (CPs). To study the environmental behavior and fate of SCCPs in the soils of urban and suburban regions, the SCCP concentrations in 88 topsoils and 15 soil columns from land of different use types (e.g., woodland, vegetable field, paddy field and greenbelt) from Guangzhou and Chengdu have been determined. The SCCP concentrations in topsoils from Guangzhou (range: 1.45–25.5 ng g− 1 dry weight (dw), average: 10.3 ng g− 1 dw) were much higher than those from Chengdu (range: 0.218–3.26 ng g− 1 dw, average: 1.43 ng g− 1 dw). When compared to previously reported SCCP levels for topsoils from other areas, the SCCP concentrations measured in the present work were quite low. Much higher SCCP concentrations were observed in the greenbelt topsoils from Chengdu relative to the values measured from woodlands and vegetable and paddy fields. The composition profiles suggest that C10Cl6–10 and C11–13Cl6–8 were the major groups of SCCPs in topsoils from the woodlands and vegetable and paddy fields in Guangzhou and Chengdu. Vertical variations of the SCCP concentrations in the soil columns suggest that less chlorinated SCCPs (Cl5–6-SCCPs) are more capable of migrating to the deeper-layer soils than more chlorinated ones (Cl9–10-SCCPs). The SCCP concentrations displayed little dependence on organic matter (OM) for most topsoils (p > 0.05), indicating that OM is not the controlling factor in the distribution of SCCPs in the soils. Capsule This study analyzed the occurrence, homologue patterns and vertical migration of SCCPs in the topsoils of two Chinese cities with different industrial structures and climate conditions.

To determine if exposure to methyl mercury (MeHg) in utero is associated with an elevated risk of neural tube defects (NTDs), we measured its concentration in the placentas of 36 anencephalic and 44 spina bifida cases, as well as in 50 healthy controls. The median MeHg concentration in NTD cases (0.49ng/g) was higher than that in controls (0.33ng/g). The crude and adjusted odds ratios (ORs) for a MeHg concentration above the median were 3.54 (95% confidence interval (CI), 1.68-7.49) and 3.64 (95% CI, 1.66-7.99), respectively. Both anencephaly and spina bifida subtypes had higher levels of MeHg than the controls. NTD risk increased for subjects in the second and third highest tertile of MeHg concentrations, with an OR of 2.24 (95% CI, 0.93-5.40) and 2.85 (95% CI, 1.17-6.94), respectively. In summary, higher placental levels of MeHg are associated with an elevated risk of NTDs.

The power threshold for low (L) to high (H) confinement mode transition achieved by radio-frequency heating and molybdenum first wall with lithium coating has been experimentally investigated on the EAST tokamak for two sets of divertor geometries and materials: tungsten/carbon divertor and full carbon divertor. For both sets of divertors, the power threshold was found to decrease with gradual accumulation of the lithium wall coating, suggesting the important role played by the low Z impurities and/or the edge neutral density on the L–H power threshold. When operating in the upper single null configuration, with the ion grad-B drift direction away from the primary X-point, a lower normalized power threshold is observed in EAST with the tungsten/carbon divertor, compared to the carbon divertor after intensive lithium wall coating. A newly installed cryopump increasing the pumping efficiency also plays an important part in the observed lower threshold. In addition, the H-mode in the Quasi-Snowflake ...

The continuous disposal of persistent organic pollutants (POPs) in South Africa (SA) warrants concern about their detrimental effects on humans and wildlife. We surveyed six dolphin species (n = 90) incidentally captured in shark net installations or stranded off the SA east and south coast from 2005 to 2009 to study the POP exposure. Sousa plumbea, an inshore and estuarine species, was found to be the most contaminated by total POPs (21 100 ng g(-1) lw) of all the dolphins off SA, followed by Tursiops aduncus (19 800 ng g(-1) lw), Lagenodelphis hosei (13 600 ng g(-1) lw), and Delphinus capensis (5500 ng g(-1) lw), whereas POP levels in the offshore or pelagic delphinids were much lower. In all delphinids, dominant pollutants were dichlorodiphenyltrichloroethanes (DDTs), which represented more than 60% of the total concentration of total POPs, followed by polychlorinated biphenyls (PCBs, 30%). Concentrations of DDTs in S. plumbea and T. aduncus off SA were among the highest levels reported in delphinids globally. Approximately half of the adult T. aduncus had PCB concentrations above the effect threshold for impairment of immune functions. The concentrations of Mirex and Dieldrin in SA delphinids were higher than those found in species from other regions of the Southern Hemisphere.

Reactive oxygen species (ROS) production from ambient fine particles has been correlated with the soluble transition metal content of PM2.5, which also has clear association with particle-mediated cardiopulmonary toxicity. Hydroxyl radical ( OH) is the most harmful ROS species through chemical reactions of redox-active particle components. Atmospheric Fe, as the dominant species of the transition metals in the atmosphere, is associated with OH generation in ambient particle extracts. Our results revealed that Fe-containing particles (18,730 in total number) contributed approximately 3.7% on average to all detected particles throughout the summer and winter sampling period in Guangzhou, which was clustered into four distinct particle classes, including Fe-rich, Metal-rich, NaK-rich and Dust-rich. Fe-rich class was the dominant one with a fraction of 61%, followed by Dust-rich (14%), Metal-rich (13%). and NaK-rich (12%). The iron oxide was enriched in the Fe-rich class. OH generation induced by Fe-containing fine particles collected in Guangzhou (GZ) was quantified in a surrogate lung fluid (SLF), and it was found that Fe-containing fine particles were generally much reactive in generating OH in the presence of four antioxidants (200 μM ascorbate, 300 μM citrate, 100 μM reduced l -glutathione, and 100 μM uric acid). The annual average OH amount produced in our samples was 132.98 ± 27.43 nmol OH mg−1 PM2.5. OH production had a clear seasonal pattern with higher amount in summer and lower in winter. By measuring the amount of total and SLF-soluble metal in our PM2.5 samples using ICP-MS, we found that ROS activities were associated with the ionizable Fe through Fenton type reactions in the Guangzhou PM2.5. Expected burdens of PM2.5 derived OH in human lung lining fluid suggests that typical daily particulate matter exposure in Guangzhou is already a concern, and it could produce much higher levels of OH, leading to higher cytotoxicity.