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Organic arsenic pollutant p-arsanilic acid (p-ASA) in wastewater can be converted into highly toxic inorganic arsenic under natural conditions, causing serious harm to the environment and human health. In this study, an Fe-based metal-organic framework (MOF) material, activated MIL-88A, was synthesized as an adsorbent to remove p-ASA in water.Various influencing factors in the material synthesis process, including temperature, time, solution, and annealing process, were investigated to obtain the optimal reaction conditions. The synthesized activated MIL-88A had great porosity and excellent adsorption capacity for p-ASA in a wide pH range (3 ∼ 10). When the pH of the solution was 6, the activated MIL-88A achieved a great adsorption capacity of 813 mg·gThe adsorption kinetics of p-ASA on the activated MIL-88A followed the pseudo-second-order models, and the adsorption isotherms can be fitted by the Langmuir models well. The adsorption behavior was spontaneous and endothermic, and was dominated by Fe-O-As coordination and hydrogen bonding.

Exploitation of the vast reserve of geothermal energy for power generation and direct use has been elevated to the top of China’s energy agenda, while the environmental impacts and human health risk have received little attention. This review systematically summarizes the environmental and human health impacts of geothermal utilization in China, and identifies the key technologies and policy measures that can be implemented to mitigate them. Geothermal fluids are typically enriched with a range of dissolved species and non-condensable gases, which originate from magma degassing and/or water-rock interaction under high temperature and pressure, and often low pH conditions in the reservoirs, and their releases could pollute local surface water, groundwater, soil, and air, and adversely affect biodiversity. The toxic elements (primarily As and F) could negatively impact the health of people living in geothermal areas through contaminated surface water, groundwater, and food crops. Among the gaseous pollutants, hydrogen sulfide often poses the most significant health concern, while radon might pose potentially significant radiological risk to the workers of geothermal spa and hot spring facilities. Improper disposal of the geothermal wastes enriched with natural radionuclides might elevate the radiation exposure of workers at geothermal facilities and people living in their vicinity. To minimize the potential environmental impacts and human health risk from large-scale expansion of geothermal exploitation, heat-extraction-only technologies should be promoted, while geothermal facilities should actively adopt pollution control and prevention measures. Government regulation and supervision can further ensure the negative environmental and human health impacts are adequately mitigated.

Due to the lack of a priori knowledge on true source makeup and contributions, whether the source apportionment results of Unmix and positive matrix factorization (PMF) are accurate cannot be easily assessed, despite the availability of built-in indicators for their goodness of fit and robustness. This study systematically evaluated, for the first time, the applicability and reliability of these models in source apportionment of soil heavy metal(loid)s with synthetic datasets generated using known source profiles and contributions and a real-world dataset as well. For eight synthetic datasets with different pollution source characteristics, feasible Unmix solutions were close to the true source component compositions (

Heavy metal pollution caused by mining activities can be harmful to soil microbiota, which are highly sensitive to heavy metal stress. This study aimed to investigate the response of soil bacterial communities to varying levels of heavy metal pollution in four types of habitats (i.e., tailing, remediation, natural recovery, and undisturbed areas) at an abandoned polymetallic mine by high-throughput 16 S rRNA gene sequencing, and to determine the dominant ecological processes and major factors driving the variations in bacterial community composition. The diversity and composition of bacterial communities varied significantly between soil habitats (p 0.05). Heterogeneous selection played a crucial role in shaping the difference of bacterial community composition between distinct soil habitats. Redundancy analysis and Pearson correlation analysis revealed that the total contents of Cu and Zn were key factors causing the difference in bacterial community composition in the tailing and remediation areas, whereas bioavailable Mn and Cd, total nitrogen, available nitrogen, soil organic carbon, vegetation coverage, and plant diversity were key factors shaping the soil bacterial structure in the undisturbed and natural recovery areas. These findings provide insights into the distribution patterns of bacterial communities in soil habitats with different levels of heavy metal pollution, and the dominant ecological processes and the corresponding environmental drivers, and expand knowledge in bacterial assembly mechanisms in mining regions.

Hypothesis Aromatic organoarsenicals are heavily used as poultry feed additives, and the application of manure containing these compounds could release toxic inorganic arsenic into the environment. Bimetal ferrites are recognized as promising sorbents in removal of organoarsenicals with formation of Fe O As complexes, and their high saturation magnetization also allows easy sorbent separation. Experiments Herein, a flower-like CoFe2O4 sorbent was synthesized through an environmental-friendly process. Findings The flower-like CoFe2O4 particles have abundant mesopores and a large specific surface area of 48.4 m2/g. At an equilibrium concentration of 80 μmol/L, the sorption capacities towards p-arsanilic acid (p-ASA), roxarsone (ROX), 4-hydroxyphenylarsonic acid (4-HPAA), 2-aminophenylarsonic acid (2-APAA), phenylarsonic acid (PAA), and 2-nitrophenylarsonic acid (2-NPAA) were 38.1, 45.7, 38.7, 39.3, 33.0, and 32.8 mg/g, respectively. Langmuir model and pseudo-second-order kinetics could well fit the sorption isotherms and rates. The sorption performance was better under acidic conditions due to enhanced electrostatic attraction. Humic acid (HA) and PO43− inhibited the sorption through competing for sorption sites, while Fe3+ promoted sorption due to formation of additional Fe O As complexes on sorbent surface. The experimental observations, spectroscopic insights, and density functional theory (DFT) calculations consistently indicate that the sorption of aromatic organoarsenicals on the flower-like CoFe2O4 particles occurs mainly through formation of inner-sphere complexes. The flower-like CoFe2O4 could be regenerated and reused over multiple cycles. The high sorption capacities, together with its magnetic property, make the flower-like CoFe2O4 an attractive sorbent for removing aromatic organoarsenicals from wastewater.

Once discharged into the environment, phenylarsenic feed additives, primarily p-arsanilic acid (p-ASA) and roxarsone (ROX), could pose potentially significant risk. A permanganate oxidation and ferric ion precipitation (KMnO4-Fe(III)) process was proposed to degrade these compounds leached from animal waste (by KMnO4) followed by sorptive removal of the arsenate released (with Fe(OH)3). The kinetics, mechanism, and pathways of p-ASA and ROX degradation in permanganate oxidation were investigated, and the effects of treatment conditions, including the dosages of reagents (KMnO4, Na2SO3, and FeCl3) and solution pH, on degradation of phenylarsenic compounds and removal of soluble manganese and inorganic arsenic were systematically evaluated. The apparent second-order rate constants for permanganate oxidation of p-ASA and ROX at pH 7.0 were determined to be 1.47 ± 0.07 and 0.13 ± 0.01 M−1·s−1, respectively. Under the optimum treatment conditions, >99% of p-ASA and ROX could be degraded (∼94% to As(V), the rest to self-coupling products) by 35 and 240 min of reaction, respectively. The overdosed KMnO4 was reduced by Na2SO3 and removed as MnO2 precipitate, followed by sorptive removal of the residual arsenic and manganese by Fe(OH)3 precipitate formed from FeCl3. The residual levels of manganese and arsenic in the solution phase could be kept below 25 and 80 μg·L−1, respectively. Both humic acid and the organic matter present in swine manure leachate greatly compromised the performance of KMnO4-Fe(III) process, while p-ASA/ROX degradation and residual manganese and arsenic control could still be achieved by substantially raising the reagent dosages. Compared to Fenton oxidation, KMnO4-Fe(III) process could obtain comparable treatment efficiency but with much less chemical consumption, and could thus serve as an economic and robust alternative method for treating p-ASA and ROX in manure leachate.

This work developed a method for rapid determination of methylmercury (MeHg) in rice, a staple cereal widely consumed in Asia, based on microwave-assisted extraction coupled with thermal decomposition amalgamation atomic absorption spectrometry (MAE-TDA-AAS). Orthogonal design was applied to optimize the parameters of MAE, and the optimal conditions were found to be as follows: 1.5 g of rice powder extracted using 12 mL toluene and 6 mL 30% HCl solution at 110 °C for 5 min under microwave irradiation. MeHg extracted into the organic phase (4.0 mL) was then back-extracted into 2.0 mL 1.5% L-cysteine solution, followed by quantitation by TDA-AAS on a direct mercury analyzer. The MeHg recovery rate of this method determined from a spiked rice sample was 80.8% (77.5–84.1%, 95% confidence limits), while those for MeHg in certified reference materials, TORT-2 and SRM-2976, were 97.6% (91.0–104.1%, 95% confidence limits) and 93.8% (90.4–97.2%, 95% confidence limits), respectively. The limit of detection and limit of quantification for MeHg in rice were 0.13 and 0.43 ng g−1, respectively, and the relative standard deviation was below 5%. The extracts of 15 rice samples collected from two provinces in China were analyzed by both TDA-AAS and the well-developed high performance liquid chromatography coupled with inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) method, and comparable results were obtained. Overall, these findings demonstrate that the MAE-TDA-AAS method developed in this study is a convenient and reliable method for quick determination of MeHg in rice and probably other food grains, and it is an order of magnitude more sensitive than the previous methods established for analysis of mercury species in fish and seafood.

Rice paddies in industrialized areas are particularly impacted by heavy metal contaminations. Based on 205 pairs of soil and rice samples collected from Yingtan, a typical industrialized region in southern China, the work was carried out to investigate the characteristics of heavy metals in soils and rice, evaluate their corresponding health risks to local residents and elucidate the migration and enrichment patterns of the trace elements from soil to rice. Approximately 98.5%, 77.6% and 70.2% of the soil samples were polluted by Cd, Pb and Cu, while 34.6%, 23.4% and 15.6% of the rice grain samples had contents of Cd, As and Pb exceeding the standard limitations, respectively. Consuming locally produced rice posed serious risks to local residents. The non-carcinogenic risks were primarily due to dietary intake of i-As and Cd, and carcinogenic risks were mainly caused by i-As in rice grains. Cd is most likely to be migrated and enriched. The bioaccumulation process is influenced by a combination of environmental factors, such as soil pH, TOC, heavy metal contents in bioavailable fractions and mineral elements, such as Al, Mn and Fe. The findings help in making effective pollution prevention and control regulations for guaranteeing the health of local residents.

A high-efficiency Z-scheme Bi

Soil heavy metal(loid) (HM) source apportionment is the prerequisite to develop suitable mitigation measures and make pollution control and prevention regulations. The selection of appropriate tools (models) for source analysis is crucial, that is especially true for large-scale regions, as the Pearl River Delta (PRD), due to the high spatial variability in soil parent materials, soil topographical feature, and wide range of anthropogenic activities. The objective of this study is to evaluate the potential applications of receptor models (positive matrix factorization [PMF] and Unmix) which have been widely used in air pollution research to quantitatively apportion sources of heavy metal(loid)s in the soils. To assist the interpretation of the derived factors (sources) of the receptor models, enrichment factors and GIS mapping were used to identify the potential relationships between the factor contributions and human activities in the study area. As the models are built on completely different algorithms, a comparative approach was adopted in addition to evaluate the impact of sample size on the model results. Factor profiles generated by different receptor models were quite similar as well as their corresponding factor contributions spatial distribution. Though the stability of their results decreases with a reduced sample size, the results of PMF were less significantly influenced by the sample size than those of Unmix. Due to the difficulty (time consuming and expensive) of soil sample collection in large-scale regions, the PMF model appears to be practically more effective than Unmix. In addition, further investigation is needed for Unmix model to understand the reason for its high sensitivity and determine an appropriate sample size.

Atmospheric coarse particulate matter (PM10) enriched with heavy metal(loid)s could pose potentially significant health risk to humans, while accurate health risk assessment calls for characterization of their bioaccessibility, besides the total contents. The health risk of major toxic heavy metal(loid)s in the PM10 from four large cities in northern China via inhalation was investigated based on their total contents and bioaccessibility. The annual mean concentrations of PM-bound Zn, As, Pb, and Mn in the atmosphere of the four cities were 650, 305, 227, and 177 ng⋅m−3, respectively. The levels of heavy metal(loid)s in the PM10 were generally higher in winter but lower in summer in all four cities, which resulted primarily from the emissions associated with coal combustion for district and household heating and the unfavorable meteorological conditions in winter. The bioaccessibility of heavy metal(loid)s in the PM10 ranged from 0.9 to 48.7%, following the general order of Mn > Co > Ni > Cd > Cu > As > Cr > Zn > Pb. Based on their total contents in the PM10, most heavy metal(loid)s posed significant public health risk via inhalation exposure in the four cities. However, after accounting for the bioaccessibility of metal(loid)s, the non-carcinogenic risk of most metal(loid)s was negligible, except for As in the PM10 of Jinzhong, while only the carcinogenic risk posed by Cr and As in the PM10 exceeded the acceptable level. These findings demonstrate the importance of characterizing the bioaccessibility of airborne PM-bound heavy metal(loid)s in health risk assessment and could guide the on-going efforts on reducing the public health risk of PM10 in northern China.

Under the significant pressure to diversify energy supply and reduce the dependence on fossil fuels, harnessing the vast geothermal resources has been made a priority in China’s renewable energy development plans. This review provided an overview on the development of geothermal power generation and direct use in China, identified the key barriers for geothermal energy utilization, particularly in power generation, and proposed corresponding measures for boosting the growth of geothermal industry. Little progress was made in geothermal power generation over the past decades, while geothermal direct use, particularly geothermal heat pumps (GHPs) and district heating, has been growing quickly. Development of geothermal power generation was primarily limited by the lack of high temperature hydrothermal resources near the major demand centers. A series of technological challenges associated with drilling under extremely high pressure and temperature conditions, transportation of heavy equipment, long-distance electricity transmission, and hot dry rock (HDR) exploitation, also hindered large-scale development of geothermal resources for power generation and district heating. There were no social barriers for geothermal exploitation except in hot spring tourism areas, while the high cost could limit the consumer acceptance of geothermal heating/cooling solutions. Significant investment in research and development of enhanced geothermal system (EGS) technologies for exploiting HDR resources and establishment of favorable policy instruments are recommended as key technological and policy measures to accelerate the growth of geothermal energy market, while the potential social barriers for the development EGS projects in the densely populated areas should also be recognized and mitigated in the future.

Waste-to-energy (WTE) incineration has been increasingly adopted for municipal solid waste (MSW) disposal in China, which already accounts for nearly 40% of the global installed capacity and electricity generation from WTE. This review identifies the growing importance of WTE incineration as a source of anthropogenic mercury emissions in China, summarizes the mercury control practices at WTE facilities, estimates the inventories of mercury emissions from WTE and those after the implementation of the more stringent air emission standards, and recommends key measures to further reduce the mercury emissions from WTE industry in China. WTE incineration in China was estimated to have a mean current mercury emission factor (EF) of 0.083 g/tonne (with 95% confidence intervals of 0.056–0.116 g/tonne) based on the mercury contents in MSW and the typical removal efficiencies of air pollution control devices (APCDs). The total mercury emissions from WTE incineration were estimated to be around 6.1 tonnes in 2016, and were predicted to reach 10.6 tonnes by 2020 based on its fast growth. The recently adopted more stringent emission standard for mercury can help curb the growth in mercury emissions from WTE incineration, while the gradual implementation of the Minamata Convention on Mercury is expected to contribute to significant reduction in the emissions of mercury from WTE incineration in the long run. Current estimations for mercury emission inventories from WTE incineration in China carry large uncertainty due to the overall scarcity of data. Thus, more work should be conducted to better monitor and quantify the mercury contents in MSW, and the mercury removal efficiencies of APCDs and the emission rates of mercury at WTE facilities. Meanwhile, China also needs to develop effective recycling and waste-sorting programs to divert the mercury-containing waste items from entering the incinerators and thus reduce the mercury emissions while promoting waste disposal by WTE.

Although metal ore mining activities are well known as an important source of heavy metals, soil pollution caused by small-scale mining activities has long been overlooked. This study investigated the pollution of surface soils in an area surrounding a recently abandoned small-scale polymetallic mining district in Guangdong province of south China. A total of 13 tailing samples, 145 surface soil samples, and 29 water samples were collected, and the concentrations of major heavy metals, including Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Pb, and Se, were determined. The results show that the tailings contained high levels of heavy metals, with Cu, Zn, As, Cd, and Pb occurring in the ranges of 739–4.15 × 103, 1.81 × 103–5.00 × 103, 118–1.26 × 103, 8.14–57.7, and 1.23 × 103–6.99 × 103 mg/kg, respectively. Heavy metals also occurred at high concentrations in the mine drainages (15.4–17.9 mg/L for Cu, 21.1–29.3 mg/L for Zn, 0.553–0.770 mg/L for Cd, and 1.17–2.57 mg/L for Pb), particularly those with pH below 3. The mean contents of Cu, Zn, As, Cd, and Pb in the surface soils of local farmlands were up to 7 times higher than the corresponding background values, and results of multivariate statistical analysis clearly indicate that Cu, Zn, Cd, and Pb were largely contributed by the mining activities. The surface soils from farmlands surrounding the mining district were moderately to seriously polluted, while the potential ecological risk of heavy metal pollution was extremely high. It was estimated that the input fluxes from the mining district to the surrounding farmlands were approximately 17.1, 59.2, 0.311, and 93.8 kg/ha/yr for Cu, Zn, Cd, and Pb, respectively, which probably occurred through transport of fine tailings by wind and runoff, and mine drainage as well. These findings indicate the significant need for proper containment of the mine tailings at small-scale metal ore mines.

Because most chickens are reared in intensive farms, where a range of feed additives are used routinely, concerns have been raised on the potential public health risk of chicken product consumption. This study was conducted to characterize the contents of trace metals in fresh chicken tissues (354 samples) on the food markets in Guangdong province of southern China, a major region of chicken production with heavy per capita chicken consumption, and to assess the public health risk from chronic dietary exposure to the trace metals through chicken consumption. With the exception of Cr, Ni, and Pb, the contents of trace metals were generally higher in the chicken giblets (livers, gizzards, hearts, and kidneys) compared to muscles (breasts and drumsticks). Chicken tissues from the urban markets generally contained higher levels of As, Cu, Mn, and Zn than those from the rural markets, while the contents of Pb were typically higher in the chicken muscles from the rural markets. Results of statistical analyses indicate that Cu, Zn, and As in the chicken tissues derived mainly from the feeds, which is consistent with the widespread use of Cu, Zn, and phenylarsenic compounds as feed supplements/additives in intensive poultry farming. No non-carcinogenic risk is found with the consumption of fresh chicken meat products on the food markets, while approximately 70% of the adult population in Guangzhou and 30% of those in Lianzhou have bladder and lung cancer risk above the serious or priority level (10−4), which arises from the inorganic arsenic contained in the chicken tissues. These findings indicate that the occurrence of inorganic arsenic at elevated levels in chicken tissues on the food markets in Guangdong province poses a significant public health risk, thus the use of phenylarsenic feed additives in China's poultry farming should be significantly reduced and eventually phased out.

N-nitrosodimethylamine (NDMA), a highly toxic and carcinogenic disinfection byproduct, cannot be efficiently removed by conventional water treatment processes, while sorption by microporous minerals, followed by destruction with microwave irradiation has been developed as a promising alternative. This work examined the impact of surface cation density and type on sorption of NDMA on dealuminated ZSM-5 zeolites, and on microwave-induced degradation of the sorbed NDMA, as well as the non-thermal effect of microwave. NDMA sorption was found to increase with the framework Si/Al ratio of dealuminated ZSM-5 zeolites (i.e., decreasing density of surface cations), and was also influenced by the type of surface cations. Degradation of the sorbed NDMA proceeded faster with increases in the power level of microwave and in the micropores with higher densities of surface cations, which was attributed to the increases in the number and/or temperature of micro-scale “hot spots” formed by microwave dielectric superheating of the surface cations. The degradation rate of sorbed NDMA was also found to be inversely correlated with the hydration free energy of surface cations present in the zeolite micropores. The apparent activation energy estimated from the temperature dependence of NDMA degradation in the micropores under microwave irradiation was 18.2 kJ/mol, which is much lower than those of typical thermolysis reactions and is indicative of significant contribution from the non-thermal effect of microwave.

Singlet oxygen (1O2) mediated self-sensitized photo-oxidation in aqueous solution is a relatively uncommon photodegradation pathway that has been reported for some organic pollutants. Such reactions have been modeled by the empirical first-order kinetics, but significant deviation occurs at high substrate concentrations and in the presence of 1O2 scavengers and in D2O matrices. A mechanistically based kinetic model was developed for 1O2 mediated self-sensitized photo-oxidation by accounting for the sensitized generation of 1O2 and the heterogeneous reaction between the substrate/sensitizer and 1O2 in the photochemical system. The initially formed 1O2 is treated in the model to be spatially correlated with its sensitizer, which could simultaneously undergo reaction and dissociation, instead of being evenly distributed in the solution instantaneously once formed. The oxidation of the substrate/sensitizer by 1O2 occurs in both the geminate pairs and in solution, while the 1O2 in solution is also quenched by the solvent and scavengers present. The model could well describe the solar photodegradation of p-arsanilic acid (p-ASA) under various initial concentrations, and predict the effect of 1O2 scavenger NaN3, and D2O matrices on degradation rate. The performance of the model was also validated by the kinetics of 1O2 mediated self-sensitized photo-oxidation of p-aminobenzoic acid (PABA), l-benzyl-3,4-dihydroisoquinoline, and 3,4-dihydropapaverine reported in the literature. Overall, this kinetic model could help better understand the fundamental processes involved in 1O2 mediated self-sensitized photo-oxidation and predict the photochemical fate of organic pollutants that undergo such photochemical transformation in sunlit surface water.

A high-efficiency Z-scheme Bi2MoO6/AgI heterojunction was designed and fabricated via in situ growth of AgI on Bi2MoO6. Its photocatalytic activity was investigated with the degradation of malachite green (MG). After 40 min of visible light irradiation, near complete degradation of MG (20 mg/L) occurred when BA11 (Bi2MoO6:AgI = 1:1, 2.0 g/L) was present, while only 29.0% and 49.7% of the MG could be degraded in the presence of Bi2MoO6 and AgI, respectively. The excellent photocatalytic activity of BA11 results from strong visible light absorption and the low recombination efficiency of photogenerated electron-hole pairs induced by the formation of heterojunction. Density function theory (DFT) calculations revealed that the formation of built-in electric field at the interface between Bi2MoO6 and AgI facilitates the effective separation and transfer of photogenerated charge carriers. Results of reuse experiments indicated that the heterostructured photocatalyst has excellent stability. Radical scavenging experiments and electron spin resonance spectra showed that superoxide radicals (O2-) and hydroxyl radicals (OH) were the major reactive oxygen species in the photocatalytic system. The photocatalytic degradation pathway of MG was proposed based on the organic degradation intermediates detected. These findings demonstrate that the mediator-free Z-scheme Bi2MoO6/AgI heterojunction could serve as a promising photocatalyst in photocatalytic treatment of organic pollutants.

The transfer rate of photo-generated electrons is a critical factor that determines the photocatalytic efficiency of Z-scheme photocatalytic systems. Here, a novel Z-scheme g-C3N4-AQ-MoO3 photocatalyst with anthraquinone (AQ) serving as an e– transfer channel for hydrogen production was proposed. Its enhanced photocatalytic activity is due to the accelerated transfer of e– in the form of charge inside AQ, which also suppresses the recombination of photo-generated e– and h+. In addition, the reduction area is significantly increased by the exfoliation of g-C3N4 into thin layers. Due to the synergistic effect of rapid e– transfer and large reduction area, Z-scheme g-C3N4-AQ-MoO3 has a high hydrogen production efficiency that can reach 2018 μmol/g with the presence of triethanolamine as a hole sacrificial agent after 180 min of simulated sunlight illumination. This work provides a new strategy to design and develop Z-scheme photocatalytic systems with excellent electron migration rates and high charge separation efficiency.

Small-scale mining activities in many developing countries have caused severe environmental issues to the surrounding areas, which ultimately threatened the health of local populations. Based on detailed characterization of the local drinking water and surface soil, as well as foodstuffs, this study comprehensively assessed the public health risk of toxic metal(loid)s to the population living in three villages surrounding an abandoned small-scale polymetallic mine in southern China. The agricultural soils contained elevated levels of Cu, Zn, As, Cd, and Pb, which originated from the mining district, and as expected, the locally cultivated rice and vegetables were contaminated by As, Cd, and Pb to varying extents. Arsenic occurred in both inorganic and organic forms in the rice and vegetables, with inorganic As (i-As) accounting for 82.2% (45.4–100%) and 94.7% (65.2–100%) of the total As contents in rice and vegetables, respectively. Results of health risk assessment indicate that the residents in the impacted villages had serious non-carcinogenic and carcinogenic risk. Dietary exposure to i-As and Cd through rice and vegetable consumption was the primary cause of non-carcinogenic risk, while i-As intake was the dominant contributor of carcinogenic risk. These findings suggest that significant environmental pollution by toxic metal(loid)s could result from small-scale metal mines, even after being abandoned, and the accumulation of the toxic metal(loid)s in food crops could pose significant health risk to the local residents. Immediate actions should be taken to discourage them from consuming the locally produced food crops, while long-term control measures for containment of toxic metal(loid) pollution are being developed, and high priority should be given to the remediation of Cd and As in the contaminated soils.

Aromatic organoarsenicals are heavily used as poultry feed additives, and the application of manure containing these compounds could release toxic inorganic arsenic into the environment. Bimetal ferrites are recognized as promising sorbents in removal of organoarsenicals with formation of FeOAs complexes, and their high saturation magnetization also allows easy sorbent separation.Herein, a flower-like CoFeThe flower-like CoFe

Phenylarsonic feed additives were once widely used in poultry and swine production around the world, which brought significant and unnecessary health risk to consumers due to elevated residues of arsenic species in animal tissues. They also increased the risk to ecosystems via releases of inorganic arsenic through their environmental transformation. Out of concern for the negative impacts on human and ecosystem health, China, one of the world's largest poultry and swine producing countries, recently banned the use of phenylarsonic feed additives in food animal production. This ban, if fully enforced, will result in reduction of approximately 1160 cancer cases per year from the consumption of chicken meat alone, and avoid an annual economic loss of nearly 0.6 billion CNY according to our risk analysis. Furthermore, the inventory of anthropogenic arsenic emissions in China will be cut by approximately one-third with the phase-out of phenylarsonic feed additives. This ban is also expected to lead to significant reduction in the accumulation of arsenic in the soils of farmlands fertilized by poultry and swine wastes and, consequently, lower the accumulation of arsenic in food crops grown on them, which could have even greater public health benefits. But effective enforcement of the ban is crucial, and it will require detailed supervision of veterinary drug production and distribution, and enhanced surveillance of animal feeds and food products. Furthermore, control of other major anthropogenic sources of arsenic is also necessary to better protect human health and the environment.

Incineration has overtaken landfilling as the most important option for disposal of the increasing volumes of municipal solid waste (MSW) generated in China. Accordingly, disposal of the incineration fly ash, which is enriched with a range of heavy metals, has become a key challenge for the industry. This review analyzes the temporal and spatial trends in the distributions of As, Cd, Cr, Cu, Ni, Pb, Zn, and Hg in MSW incineration fly ash between 2003 and 2017, and estimates the inventories of heavy metals associated with the fly ash and the average levels of heavy metals in Chinese MSW based on their mass flow during MSW incineration. It was estimated that MSW incinerators in China released approximately 1.12 × 102, 2.96 × 103, 1.82 × 102, 3.64 × 104, 1.00 × 102, 7.32 × 103, 2.42 × 102, and 1.47 × 101 tonnes of Cd, Pb, Cr, Zn, Ni, Cu, As, and Hg, respectively, with the fly ash in 2016. Due to the much greater fly ash generation rate, the incinerators based on circulating fluidized bed combustor (CFBC) technology released more heavy metals during incineration of MSW compared to those based on grate furnace combustor (GFC) technology. Results of mass-flow modeling indicate that the geometric mean contents of Cd, Pb, Cr, Zn, Ni, Cu, As, and Hg in Chinese MSW were 3.0, 109, 101, 877, 34, 241, 21, and 1.7 mg/kg, respectively, which are comparable to those in the MSW from other countries. To protect the environment from the significant potential ecological risk posed by heavy metals in the mismanaged fly ash, strict regulation enforcement and compliance monitoring are necessary to reduce the heavy metal pollution brought by improper disposal of MSW incineration fly ash, and more research and development efforts on advanced technologies for stabilization of heavy metals in fly ash and its environmentally sound reuse can help mitigate its environmental risk.

Plastic components of e-waste contain high levels of brominated flame retardants (BFRs), whose releases cause environmental and human health concerns. This study characterized the release kinetics of polybrominated diphenyl ethers (PBDEs) from millimeter-sized granules processed from the plastic exteriors of two scrap computer displays at environmentally relevant temperatures. The release rate of a substitute of PBDEs, 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), from the waste plastics, was reported for the first time. Deca-BDE was the most abundant PBDE congeners in both materials (87–89%), while BTBPE was also present at relatively high contents. The release kinetics of BFRs could be modeled as one-dimensional diffusion, while the temperature dependence of diffusion coefficients was well described by the Arrhenius equation. The diffusion coefficients of BFRs (at 30 °C) in the plastic matrices were estimated to be in the range of 10–27.16 to 10–19.96 m2·s–1, with apparent activation energies between 88...

The overuse and misuse of veterinary drugs, particularly antimicrobials, in food animal production in China cause environmental pollution and wide food safety concerns, and pose public health risk with the selection of antimicrobial resistance (AMR) that can spread from animal populations to humans. Elevated abundance and diversity of antimicrobial resistance genes (ARGs) and resistant bacteria (including multi-drug resistant strains) in food-producing animals, food products of animal origin, microbiota of human gut, and environmental media impacted by intensive animal farming have been reported. To rein in drug use in food animal production and protect public health, the government made a total of 227 veterinary drugs, including 150 antimicrobial products, available only by prescription from licensed veterinarians for curing, controlling, and preventing animal diseases in March 2014. So far the regulatory ban on non-therapeutic use has failed to bring major changes to the long-standing practice of drug overuse and misuse in animal husbandry and aquaculture, and significant improvement in its implementation and enforcement is necessary. A range of measures, including improving access to veterinary services, strengthening supervision on veterinary drug production and distribution, increasing research and development efforts, and enhancing animal health management, are recommended to facilitate transition toward rational use of veterinary drugs, particularly antimicrobials, and to reduce the public health risk arising from AMR development in animal agriculture.

The wide occurrence of Cd-contaminated rice in southern China poses significant public health risk and deserves immediate action, which arises primarily from extensive metal (including Cd) contamination of paddies with the fast expansion of nonferrous metal mining and smelting activities. Accumulation of Cd in rice grains can be reduced by removing Cd from the contaminated paddy soils, reducing its bioavailability, and controlling its uptake by rice plants. Although a range of measures can be taken to rehabilitate Cd-contaminated lands, including soil replacement and turnover, chemical washing, and phytoremediation, they are either too expensive and/or too slow. Various amendment materials, including lime, animal manures, and biochar, can be used to immobilize Cd in soils, but such fixation approach can only temporarily reduce Cd availability to rice uptake. Cultivation of alternative crops with low Cd accumulation in edible plant parts is impractical on large scales due to extensive contamination and food security concerns in southern China. Transgenic techniques can help develop rice cultivars with low Cd accumulation in grains, but little public acceptance is expected for such products. As an alternative, selection and development of low-Cd rice varieties and hybrids through plant biotechnology and breeding, particularly, by integration of marker-assisted selection (MAS) with traditional breeding, could be a practical and acceptable option that would allow continued rice production in soils with high bioavailability of Cd. Plant biotechnology and breeding can also help develop Cd-hyperaccumulating rice varieties, which can greatly facilitate phytoremediation of contaminated paddies. To eliminate the long-term risk of Cd entering the food chain, soils contaminated by Cd should be cleaned up when cost-effective remediation measures are available. Keywords: Cadmium-contaminated rice, Dietary intake, Health risk, Phytoavailability, Soil remediation, Plant biotechnology and breeding

Sorption of 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) on a range of dealuminated zeolites were investigated to understand the mechanism of their sorption on microporous minerals, while the influence of common metal cations, solution pH, and humic acid was also studied. Sorption of chlorophenols was found to increase with the hydrophobicity of the sorbates and that of the microporous minerals, indicating the important role of hydrophobic interactions, while sorption was also stronger in the micropores of narrower sizes because of greater enhancement of the dispersion interactions. The presence of metal cations could enhance chlorophenol sorption due to the additional electrostatic attraction between metal cations exchanged into the mineral micropores and the chlorophenolates, and this effect was apparent on the mineral sorbent with a high density of surface cations (2.62 sites/nm(2)) in its micropores. Under circum-neutral or acidic conditions, neutral chlorophenol molecules adsorbed into the hydrophobic micropores through displacing the "loosely bound" water molecules, while their sorption was negligible under moderately alkaline conditions due to electrostatic repulsion between the negatively charged zeolite framework and anionic chlorophenolates. The influence of humic acid on sorption of chlorophenols on dealuminated Y zeolites suggests that its molecules did not block the micropores but created a secondary sorption sites by forming a "coating layer" on the external surface of the zeolites. These mechanistic insights could help better understand the interactions of ionizable chlorophenols and metal cations in mineral micropores and guide the selection and design of reusable microporous mineral sorbents for sorptive removal of chlorophenols from aqueous stream.

Being highly water-soluble, phenylarsonic feed additives discharged in animal wastes can easily accumulate in surface water bodies. The photodegradation mechanism, kinetics, and pathways of p-arsanilic acid (p-ASA), 4-hydrophenylarsonic acid (4-HPAA), and phenylarsonic acid (PAA) in water under simulated and natural sunlight irradiation were investigated. The -AsO(OH)2 group was cleaved from the aromatic ring during photodegradation, and p-benzoquinone and p-hydroquinone were formed as the major organic degradation intermediates. Experimental results did not indicate any significant direct photolysis of the phenylarsonic compounds under simulated and natural sunlight irradiation, but consistently showed that they sensitized the formation of singlet oxygen, which was responsible for their photodegradation and oxidation of the As(III) released. A simple (1)O2-based "heterogeneous" model was developed, which could well describe the kinetics of (1)O2 formation and phenylarsonic compound photodegradation under various conditions. Indirect photolysis caused by inorganic ions commonly present in natural waters was negligible, while natural organic matter could significantly inhibit their photodegradation. The half-lives of p-ASA, 4-HPAA, and PAA photodegradation under simulated sunlight irradiation (765 W m(-2), 25 °C) were 11.82 ± 0.19, 20.06 ± 0.10, and 135 ± 6.0 min, respectively, while their degradation rates under natural sunlight in the Pearl River Delta of southern China were 5 times slower due to lower irradiation intensity and water temperatures (19-23 °C).

A novel direct Z-scheme NiGa2O4/CeO2 nanocomposite was designed and prepared via simple sol-hydrothermal and calcination methods, and its sonocatalytic activity was tested by studying the degradation of a model antimicrobial agent, malachite green (MG), under ultrasonic irradiation. Near complete (96.2%) degradation of MG (at 10 mg/L) could be achieved by the NiGa2O4/CeO2 nanocomposite (at 1.0 g/L) after ultrasonic irradiation (40 kHz, 300 W) for 60 min at 25 °C. Under the same conditions, only 51.2 and 72.0% of the MG degraded in the presence of NiGa2O4 and CeO2 (at 1.0 g/L), respectively. These results demonstrate that the direct Z-scheme NiGa2O4/CeO2 nanocomposite has excellent sonocatalytic activity, which is attributed to the matching band-gaps between NiGa2O4 and CeO2. The sonocatalytic activity of NiGa2O4/CeO2 nanocomposite decreased by 17% after four cycles of reuse, which is indicative of relatively good reusability. Scavenging experiments revealed that sonocatalytic degradation of MG results from the combined action of hydroxyl radicals ( OH) and holes (h+), with the latter having a greater contribution. The pathways and mechanism of MG degradation were proposed based on the degradation intermediates detected. The results demonstrate that the prepared direct Z-scheme NiGa2O4/CeO2 nanocomposite worked as designed and exhibited high and stable sonocatalytic activity during MG degradation, and could thus serve as a promising candidate in sonocatalytic treatment of other organic pollutants in wastewaters. The findings also provide new insights on the mechanism of sonocatalytic degradation and the design of efficient Z-scheme sonocatalysts.

Highlights • Internal diffusion often controls the releases of flame retardants from microplastics. • Fick's law can describe the releases of additive flame retardants from microplastics. • Effects of temperature, plastic matrix, and particle size can be predicted by models. • Weathering of plastic matrix can greatly accelerate the releases of flame retardants. • Low fluxes of flame retardants released from microplastics pose no risk to ecosystem. The widely occurring debris of plastic materials, particularly microplastics, can be an important source of flame retardants, which are one of the main groups of chemicals added in the production of plastics from polymers. This review provides an overview on the use of flame retardants in plastic manufacturing, the kinetics of their releases from microplastics, the factors affecting their releases, and the potential environmental and ecosystem risk of the released flame retardants. The releases of flame retardants from microplastics typically involve three major steps: internal diffusion, mass transfer across the plastic-medium boundary layer, and diffusion in the environmental medium, while the overall mass transfer rate is commonly controlled by diffusion within the plastic matrix. The overall release rates of additive flame retardants from microplastics, which are dependent on the particle's geometry, can often be described by the Fick's Law. The physicochemical properties of flame retardant and plastic matrix, and ambient temperature all affect the release rate, which can be predicted with empirical and semi-empirical models. Weathering of microplastics, which reduces their particle sizes and likely disrupts their polymeric structures, can greatly accelerate the releases of flame retardants. Flame retardants could also be released directly from the microplastics ingested by aquatic organisms and seabirds, with physical and chemical digestion in the bodies significantly enhancing their release rates. Limited by the extremely slow diffusion in plastic matrices, the fluxes of flame retardants released from microplastics are very low, and are unlikely to pose significant risk to the ecosystem in general. More research is needed to characterize the mechanical, chemical, and biological processes that degrade microplastics and accelerate the releases of flame retardants and to model their release kinetics from microplastics, while efforts should also be made to develop environmentally benign flame retardants to ultimately minimize their risk to the environment and ecosystem.

Decabromodiphenyl ether (deca-BDE or BDE-209) is a major brominated flame retardant released from plastics in thermal processing of e-waste, and there is a significant need for developing effective technologies for its destruction. This study reports a novel treatment for complete debromination and destruction of BDE-209 by adsorbing it onto porous minerals followed by microwave irradiation. Being highly hydrophobic, BDE-209 could be sorbed efficiently by porous mineral sorbents, with the density and type of surface cations of the sorbents apparently playing little role. Microwave irradiation caused rapid degradation of the BDE-209 sorbed on the porous minerals, and the fastest degradation occurred on the microporous minerals, with the density and type of surface cations present in the mineral micropores had significant impact on the degradation rate. Evolution of the degradation intermediates during the course of microwave irradiation indicates that the sorbed BDE-209 underwent pyrolytic decomposition, involving a series of reactions, including cleavage of the ether bond, debromination, hydroxylation, ring cleavage, and oxidation. Microwave-induced degradation could cause full mineralization of the sorbed BDE-209 without producing lower brominated congeners, which is supported by the results of density functional theory (DFT) calculations and infrared spectra. Together, these findings demonstrate that microporous mineral sorption coupled with microwave irradiation could be a rapid and efficient technology for destruction of BDE-209 and other polybrominated diphenyl ethers (PBDEs).

Highlights • Leaching rates of BFRs were controlled by diffusion within the plastic matrix. • The diffusion coefficients of BFRs in ABS ranged from 10−28.30 to 10−20.84 m2 s−1 • The activation energies for diffusion of BFRs ranged from 64.1 to 131.8 kJ mol−1 • Diffusion coefficients of BFRs in plastic matrix depend on their molecular sizes. • Diffusion coefficients show dependence on the plastic's glass transition temperature. Microplastics (

Response surface methodology was applied to optimize the parameters for microwave-assisted extraction of six major inorganic and organic arsenic species (As(III), As(V), dimethyl arsenic acid, monomethyl arsenic acid, p-arsanilic acid, and roxarsone) from chicken tissues, followed by detection using a high-performance liquid chromatography with inductively coupled mass spectrometry detection method, which allows the simultaneous analysis of both inorganic and organic arsenic species in the extract in a single run. Effects of extraction medium, solution pH, liquid-to-solid ratio, and the temperature and time of microwave-assisted extraction on the extraction of the targeted arsenic species were studied. The optimum microwave-assisted extraction conditions were: 100 mg of chicken tissue, extracted by 5 mL of 22% v/v methanol, 90 mmol/L (NH4 )2 HPO4 , and 0.07% v/v trifluoroacetic acid (with pH adjusted to 10.0 by ammonium hydroxide solution), ramping for 10 min to 71°C, and holding for 11 min. The method has good extraction performance for total arsenic in the spiked and nonspiked chicken tissues (104.0 ± 13.8% and 91.6 ± 7.8%, respectively), except for the ones with arsenic contents close to the quantitation limits. Limits of quantitation (S/N = 10) for As(III), As(V), dimethyl arsenic acid, monomethyl arsenic acid, p-arsanilic acid, and roxarsone in chicken tissues using this method were 0.012, 0.058, 0.039, 0.061, 0.102, and 0.240 mg/kg (dry weight), respectively.

Animal wastes from concentrated animal feeding operations (CAFOs) can cause soil arsenic pollution due to the widespread use of organoarsenic feed additives. This study investigated the arsenic pollution of surface soils in a typical CAFO zone, in comparison with that of agricultural soils in the Pearl River Delta, China. The mean soil arsenic contents in the CAFO zone were elevated compared to those in the local background and agricultural soils of the Pearl River Delta region. Chemical speciation analysis showed that the soils in the CAFO zone were clearly contaminated by the organoarsenic feed additive, p-arsanilic acid (ASA). Transformation of ASA to inorganic arsenic (arsenite and arsenate) in the surface soils was also observed. Although the potential ecological risk posed by the arsenic in the surface soils was relatively low in the CAFO zone, continuous discharge of organoarsenic feed additives could cause accumulation of arsenic and thus deserves significant attention.

Arsenic-based feed additives, such as roxarsone (ROX), are still legally and widely used in food animal production in many countries. This study was conducted to systematically characterize the content and speciation of arsenic in chicken tissues from live poultry markets and in commercial chicken feeds in Guangdong, a major poultry production and consumption province in China, and to assess the corresponding public health risk. The total arsenic contents in the commercial feeds could be modeled as a mixture of two log-normal distributions (geometric means: 0.66 and 17.5 mg/kg), and inorganic arsenic occurred at high levels (0.19-9.7 mg/kg) in those with ROX detected. In general, chicken livers had much higher contents of total arsenic compared to the muscle tissues (breast and drumstick), and chicken muscle from the urban markets contained arsenic at much higher levels than that from the rural markets. The incremental lifetime cancer risk (bladder and lung cancer) from dietary exposure to arsenic contained in chicken meat products on local markets was above the serious or priority level (10

With significant water savings and low maintenance requirements, artificial turf is increasingly promoted as a replacement for natural grass on athletic fields and lawns. However, there remains the question of whether it is an environmentally friendly alternative to natural grass. The major concerns stem from the infill material that is typically derived from scrap tires. Tire rubber crumb contains a range of organic contaminants and heavy metals that can volatilize into the air and/or leach into the percolating rainwater, thereby posing a potential risk to the environment and human health. A limited number of studies have shown that the concentrations of volatile and semivolatile organic compounds in the air above artificial turf fields were typically not higher than the local background, while the concentrations of heavy metals and organic contaminants in the field drainages were generally below the respective regulatory limits. Health risk assessment studies suggested that users of artificial turf fields, even professional athletes, were not exposed to elevated risks. Preliminary life cycle assessment suggested that the environmental impacts of artificial turf fields were lower than equivalent grass fields. Areas that need further research to better understand and mitigate the potential negative environmental impacts of artificial turf are identified.

Abandoned tailings are one of the most important sources of heavy metal pollution in the areas surrounding mining districts, and significant leaching of heavy metals could be brought by precipitation. This study investigated the leaching of heavy metals from the tailings of a small-scale abandoned polymetallic mine in south China by rainwater with batch and column tests and evaluated the associated environmental impact. The mean contents of Cr, Ni, Cu, Zn, As, Cd, and Pb in the un-weathered mine tailings were 1.46 × 102, 3.11 × 102, 4.10 × 103, 2.18 × 104, 2.82 × 102, 5.65 × 102, and 8.74 × 103 mg/kg, respectively, and appreciable fractions of Cd, Zn, Cu, and Cr in the tailings were present in the acid soluble form. Batch and column leaching tests consistently showed that significant quantities of heavy metals could be released from the mine tailings. Based on the results of column leaching tests, it was estimated that the average fluxes of Cr, Ni, Cu, Zn, As, Cd, and Pb from the mine tailings at the studied mining district leached by precipitation were 3.20, 38.3, 12.5, 1.52 × 104, 104, 1.08, and 9.26 g/ha/yr, respectively. The metal-rich tailing leachate would impact the quality of surface water and soils downhill of the mining district, and pose significant potential ecological risk to the farmland soils, which are irrigated by local surface water. These findings indicate the importance of tailings as a source of heavy metals in the mining districts of south China with heavy precipitation, as well as the need for mitigating the releases of heavy metals and the associated environmental impact from abandoned mine tailings.

The ever increasing water demands arising from population and economic growth during China's industrial transition exerts significant stress on the country's limited freshwater resources. Meanwhile, widespread water pollution that occurred during the course of industrialization exacerbates the water shortages. This work presents an overview on the water shortages and water pollution in China, and analyzes the root causes of water pollution—increased pollutant discharges from industrial, municipal and agricultural sources, excessive water abstraction from the environment, and poor water resources management and enforcement of pollution control regulations. The three key drivers of long-term water quality improvement, namely, economic transformation, technological innovation, and institutional and policy reforms, are then discussed in details. The trend of China's surface water quality over the last two decades supports that China is approaching the critical point in its industrial transition where reduction of pollution and improvement of environmental quality are going to occur. Policy measures and institutional reforms are also recommended to accelerate the reversal of surface water quality in China.

China, already the largest generator of hydroelectricity, plans to accelerate dam construction. This has led to warnings that increased emissions of greenhouse gases, particularly methane, from Chinese reservoirs could constitute a 'global warming time-bomb'. A review of evidence on emissions from the Three Gorges Reservoir — the world's largest — indicates that such fears are probably misplaced. Already the largest generator of hydroelectricity, China is accelerating dam construction to increase the share of hydroelectricity in its primary energy mix to reduce greenhouse gas emissions. Here, we review the evidence on emissions of GHGs, particularly methane, from the Three Gorges Reservoir, and argue that although the hydroelectric reservoirs may release large amounts of methane, they contribute significantly to greenhouse gas reduction by substitution of thermal power generation in China. Nonetheless, more systematic monitoring and modelling studies on greenhouse gas emissions from representative reservoirs are necessary to better understand the climate impact of hydropower development in China.

Stanford University's Education Program for Gifted Youth (EPGY) conducted a randomized-treatment experiment during the 2006–2007 school year to test the efficacy, for Title I students, of the technological and individualized EPGY Kindergarten through Grade 5 Mathematics Course Sequence, modified for the Title I schools. Restricting attention to students who were in the top half of the distribution of correct first-exercise attempts (a measure of work and engagement), we found substantial and statistically significant improvements in the 2007 California Standard Math Tests (CST07) scores compared to those of matched control students. Gains in second grade were larger than those in Grades 3 to 5. Less able students, as measured by their 2006 CST mathematics scores, also had, on average, larger gains.

Organoarsenic compounds, such as roxarsone (3-nitro-4-hydroxyphenylarsonic acid, ROX) and p-arsanilic acid (ASA), are widely used as animal feed additives, while animal wastes bearing these compounds are often used to fertilize agricultural land, which can cause arsenic pollution of soil, surface water, and groundwater. Determination of a number of inorganic and organic arsenic species in a variety of environmental matrices is necessary to study the environmental fate of organoarsenic feed additives and to assess their risk. A robust analytical method was developed in this work for precise and accurate quantification of ROX, ASA, dimethyl arsenic acid (DMA), monomethyl arsenic acid (MMA), arsenate [As(V)], and arsenite [As(III)] by HPLC–ICP-MS with gradient elution. Extraction conditions for recovering the inorganic and organic arsenic species from soils and sediments were also optimized, and the best results were obtained with 0.5 mol·L− 1 H3PO4 under constant shaking for 16 h. This method was applied in determining the levels of inorganic and organic arsenic species in sediments, soils, and surface water surrounding several swine farms in the Pearl River Delta in southern China and the results showed that the environmental media were already impacted by organoarsenic feed additives.

Coal burning in power plants and industrial boilers is the largest combustion source of mercury emissions in China. Together, power plants and industrial boilers emit around 250 tonnes of mercury each year, or around half of atmospheric mercury emissions from anthropogenic sources in the country. Power plants in China are generally equipped with multi-pollutant control technologies, which offer the co-benefit of mercury removal, while mercury-specific control technologies have been installed in some facilities. In contrast, most industrial boilers have only basic or no flue gas cleaning. A combination of measures, including energy conservation, coal switching and blending, reducing the mercury contents of coals through washing, combustion controls, and flue gas cleaning, can be used to reduce mercury emissions from these stationary combustion sources. More stringent emission standards for the major air pollutants from coal-fired power plants and industrial boiler, along with standards for the previously unregulated mercury, were implemented recently, which is expected to bring significant reduction in their mercury emissions through the necessary upgrades of multi-pollutant and mercury-specific control technologies. Meanwhile, strong monitoring capacity and strict enforcement are necessary to ensure that the combustion sources operate in compliance with the new emission standards and achieve significant reduction in the emissions of mercury and other air pollutants.

China has invested heavily on alternative energy, but the effectiveness of such energy sources at substituting the dominant coal-fired generation remains unknown. Here we analyse the displacement of fossil-fuel-generated electricity by alternative energy, primarily hydropower, and by trans-provincial imported electricity in China between 1995 and 2014 using two-way fixed-effects panel regression models. Nationwide, each unit of alternative energy displaces nearly one-quarter of a unit of fossil-fuel-generated electricity, while each unit of imported electricity (regardless of the generation source) displaces ∼0.3 unit of fossil-fuel electricity generated locally. Results from the six regional grids indicate that significant displacement of fossil-fuel-generated electricity occurs once the share of alternative energy in the electricity supply mix exceeds ∼10%, which is accompanied by 10–50% rebound in the consumption of fossil-fuel-generated electricity. These findings indicate the need for a policy that integrates carbon taxation, alternative energy and energy efficiency to facilitate China's transition towards a low-carbon economy., Alternative energy is widely believed to proportionally displace fossil fuels. Here, the authors analyse displacement values for China between 1995 and 2014 and show that alternative energy, primarily hydropower, displaced ∼1/4 of a unit of fossil electricity, twice the global average.

The traditional industrial operations are well recognized as an important source of heavy metal pollution, while that caused by the e-waste recycling activities, which have sprouted in some developing countries, is often overlooked. This study was carried out to compare the status of soil heavy metal pollution caused by the traditional industrial operations and the e-waste recycling activities in the Pearl River Delta, and assess whether greater attention should be paid to control the pollution arising from e-waste recycling activities. Both the total contents and the chemical fractionation of major heavy metals (As, Cr, Cd, Ni, Pb, Cu, and Zn) in 50 surface soil samples collected from the e-waste recycling areas and 20 soil samples from the traditional industrial zones were determined. The results show that the soils in the e-waste recycling areas were mainly polluted by Cu, Zn, As, and Cd, while Cu, Zn, As, Cd, and Pb were the major heavy metals in the soils from the traditional industrial zones. Statistical analyses consistently show that Cu, Cd, Pb, and Zn in the surface soils from both types of sites were contributed mostly by human activities, while As, Cr, and Ni in the soils were dominated by natural background. No clear distinction was found on the pollution characteristic of heavy metals in the surface soils between the e-waste recycling areas and traditional industrial zones. The potential ecological risk posed by heavy metals in the surface soils from both types of sites, which was dominated by that from Cd, ranged from low to moderate. Given the much shorter development history of e-waste recycling and its largely unregulated nature, significant efforts should be made to crack down on illegal e-waste recycling and strengthen pollution control for related activities.