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Abstract Novel adsorbents with low cost and high efficiency that do not produce secondary pollutants are vital for removing gaseous elemental mercury (Hg0) from coal-fired power plants. In this study, eight diatomite-based adsorbents were developed and used to remove Hg0 in a bench-scale fixed-bed reactor. The effects of active substances, reaction temperature, and gas components on the Hg0 removal performance of diatomite (Dia) and the mechanisms were investigated. After modification, the specific surface area of diatomite increased by 2-to-12 fold, and the Hg0 removal performance was greatly improved. The Hg0 removal efficiencies of the adsorbents decreased in the following order: I-Dia > Br-Dia > Cl-Dia. The Hg0 removal efficiency of CuBr 2 -Dia reached 91% in the simulated flue gas at the optimal reaction temperature (140 °C). The simultaneous presence of O 2 and HCl promoted the Hg0 removal by CuBr 2 -Dia. NO alone also played a significant role in Hg0 removal. However, SO 2 exhibited clear inhibitory effect. The average Hg0 removal efficiencies of CuBr 2 -Dia were 60% under 1200 ppm SO 2 , 87% under 1200 ppm SO 2 + 300 ppm NO, and 93% under 4% O 2 + 1200 ppm SO 2 + 300 ppm NO. The changes in the active adsorption sites caused by NO, and those caused by NO + SO 2 were different and irreversible. During the Hg0 removal process, Hg0 was oxidized to the Hg2+ or Hg+ species, while Cu2+ and Br radicals were reduced to Cu+ and Br−, respectively. Graphical abstract Unlabelled Image Highlights • Low cost and high efficiency adsorbents needed for Hg0 removal from flue gas. • Diatomite-based adsorbents exhibited excellent performance for Hg0 removal. • CuBr 2 -Dia had high Hg0 removal efficiency at 60–180 °C. • NO alleviated the inhibitory effect of SO 2 on Hg0 removal by CuBr 2 -Dia. • NO and NO + SO 2 caused distinct changes in the surface chemistry of adsorbent. [ABSTRACT FROM AUTHOR]

Marine trade has significantly expanded over the past decades aiding to the economic development of the maritime countries, yet, this has been associated with a considerable increase in pollution emission from shipping operation. This study aims at considering both sides of the spectrum at the same time, which is including both public and shipping business. Of the key significance would be to optimize the operation of the shipping industry, such that its impact on air pollution is minimized, without, however, significant escalation of its cost, and therefore to protect the whole seaborne trade. To do this, we considered the impacts of three control strategies, including the current emission control area (ECA) design, as well two additional ones. Thus the first scenario (DECA1) was based on the China's domestic emission control area (DECA), which was set up in 2016. The DECA1 scale was only 12 nautical miles, which was much smaller than the emission control areas in US or Europe. We defined the second scenario (DECA2), by stretching the zone to 200 nautical miles towards the ocean, modeling it on the ECA in North America. The third scenario (DECA3), on the other hand, expanded the 12 nautical miles control zone along the whole coastline. To investigate the impact of shipping emissions on air quality, a shipping emission calculation model and an air quality simulation model were used, and Pearl River Delta (PRD), China was chosen to serve as a case study. The study demonstrated that in 2013 marine shipping emissions contributed on average 0.33 and 0.60 μg·m − 3 , respectively to the land SO 2 and PM 2.5 concentrations in the PRD, and that the concentrations were high along the coastline. The DECA1 policy could effectively reduce SO 2 and PM 2.5 concentrations in the port regions, and the average reduction in the land area were 9.54% and 2.7%, respectively. Compared with DECA1, DECA2 would not measurably improve the air quality, while DECA3 would effectively decrease the pollution in the entire coast area. Thus, instead of expanding emission control area far to the ocean, it is more effective to control emissions along the coastline to secure the best air quality and lower the health impacts. By doing this, 19 million dollars of fuel cost could be saved per year. The saved cost could help the ship owners to endure, considering the current low profits of the seaborne trade, and thus to protect the overall growth of the economy. [ABSTRACT FROM AUTHOR]

Selective adsorption via the size matching effect is one of the most effective strategies for separating and analyzing low levels of organic molecules. Herein, multicomponent covalent organic frameworks (MC-COFs) with tunable pore sizes are constructed by using one knot (1,3,5-triformylphloroglucinol, Tp) and two organic linkers (p -phenylenediamine, Pa; benzidine, BD). The pore sizes of the MC-COFs composed of TpPaBD X (X = [BD]/([Pa] + [BD]) × 100 = 0, 25, 50, 75, and 100) range from 0.5–1.5 to 0.5–2.2 nm due to variations in the initial organic linker ratios. When coupling TpPaBD X -based solid-phase microextraction (SPME) with constant flow desorption ionization mass spectrometry (CFDI-MS), these MC-COFs feature better selective adsorption performance for tetrabromobisphenol A (TBBPA) derivatives than TpPa with a smaller pore size, TpBD with a larger pore size and even some commercial fibers (e.g., polydimethylsiloxane/divinylbenzene (PDMS/DVB)-, polyacrylate (PA)- and PDMS-coated fibers). The improved method involving MC-COF TpPaBD 50 also presents favorable stability with relative standard deviations (RSD, 1 μg L−1) for single fibers of 5.5–7.9% (n = 7) and fiber-to-fiber of 6.6–7.8% (n = 7). Due to the decreased limits of detection and quantification (0.5–12 and 1.6–40 ng L−1), and reduced separation and detection time (7 min), ultratrace levels of TBBPA derivatives in real water samples are successfully detected. The proposed method shows great potential for the rapid tracing of the distribution, transportation and transformation of TBBPA derivatives to better understand their ecotoxicological effects in environmental media. Unlabelled Image • MC-COFs with tunable pore size were prepared and employed as SPME coatings. • The proposed method toward TBBPA derivatives in time-saving and sensitivities. • The salt-tolerant ability is conductive for directly analyzing saline water. [ABSTRACT FROM AUTHOR]

An emission inventory of precursors is a prerequisite for the simulation of secondary organic aerosol (SOA), which could provide valuable information on the evolution of precursors, formation of SOA, and its influence on fine particle (PM 2.5) abundance, oxidative capacity, and climate change. However, an emission inventory of semi-volatile and intermediate volatility organic compounds (S/IVOCs), the key precursor of SOA, particularly the gridded inventory that is appropriate for input into regional air quality models, remains limited in China, leading to an incomplete understanding of S/IVOCs sources and roles in SOA formation and the atmospheric environment. Therefore, a gridded emission inventory of S/IVOCs in China for 2016 was developed based on ample source-specific measured data on emission ratios of S/IVOCs to primary organic aerosols (POA) from literatures. The total emission of S/IVOCs was estimated to be 9.6 Tg, and industry and residential sectors were major sources of S/IVOCs, with contributions of 48.0% and 30.2%, respectively. The spatial variations suggested that S/IVOC emissions were mainly distributed in the highly industrialized and urbanized regions in China, such as Beijing–Tianjin–Hebei (BTH), the Yangtze River Delta (YRD), the Pearl River Delta (PRD), and the Sichuan–Chongqing (SC) regions, though the contributions and temporal patterns varied between different regions. Furthermore, uncertainty of the emission inventory was estimated to be within the range of −66%–153%, which was mainly attributed to emission ratios of IVOCs/POA for industry, transportation, and power plants. The gridded emission inventory developed in this study can be used to estimate the emissions of S/IVOCs in different regions, and can be applied to different models for a better understanding of the environmental effects of S/IVOCs. Unlabelled Image • A comprehensive gridded emissions inventory of S/IVOCs over China was established with the uncertainty range of −66–153%. • Industry and residential sources were top two contributors to S/IVOC emissions in China. • High S/IVOC emissions were present in winter and mainly distributed in the highly industrialized and urbanized regions (BTH, YRD, PRD and SC) of China. [ABSTRACT FROM AUTHOR]

Arsenic (As) and cadmium (Cd) typically exhibit divergent fates in soil, which complicates efforts to decrease As and Cd accumulation in the edible parts of crops. Here, we performed pot experiments to examine the effect of sulfate application on As and Cd accumulation in the grain of wheat grown in contaminated soil. Compared to the control (no sodium sulfate addition), application of 120 mg kg−1 sodium sulfate decreased the rhizosphere soil pH from 7.27 to 7.10 and increased the soil extractable Cd concentration; however, it did not significantly influence the soil extractable As concentration. However, sodium sulfate addition decreased As and Cd concentrations in wheat grain, in association with decreased As and Cd translocation from root and straw to grain, rather than from soil to root. Furthermore, sodium sulfate addition significantly decreased membrane lipid peroxidation and enhanced photosynthesis, while increasing the uptake of nitrogen, phosphorus, and sulfur. These effects increased the growth and grain weight of plants grown in As and Cd co-contaminated soil. Our findings provide insight into the mechanisms by which sulfate modulates As and Cd uptake and translocation in wheat; moreover, our findings will enable formulation of strategies to decrease As and Cd concentrations in the grain of wheat grown in As and Cd co-contaminated soil. Unlabelled Image • Sulfate application increased the growth and grain yield of wheat grown in As and Cd co-contaminated soil. • Sulfate application did not reduce As and Cd bioavailability in wheat rhizosphere soil. • Sulfate application increased As and Cd concentrations in root, but reduced them in grain. • Sulfate application increased the uptake of N, P, and S by wheat plants. • Sulfate application increased photosynthesis and reduced lipid peroxidation. [ABSTRACT FROM AUTHOR]

• Alcaligenes sp. TB coupled with nZVI/Pd increased NO3−–N removal by 31.5% within 28 h. • nZVI/Pd exhibited less inhibition on cell growth , NADH/NAD+ and electron transfer. • Pd increased cell membrane rigidity by increasing tran/cis isomerization ratio (317.7% of control) to enhance the resistance of nZVI. The microbial reduction of nitrate in the presence of nanoscale zero-valent iron (nZVI) was evaluated to assess the feasibility of employing nZVI for biological denitrification treatment. The effect of modified nZVI on the growth, metabolism, and denitrification performance of Alcaligenes sp. TB under aerobic conditions was studied. Results showed that Alcaligenes sp. TB with nZVI/Pd had 31.5% increase in nitrate removal and 18.1% decrease in nitrite accumulation within 28 h. nZVI/Pd exhibited less inhibition on the cell growth (OD 600 = 0.725), NADH/NAD+ ratio (86% of control), and electron transfer system activity (68.5% of control). In addition, nZVI/Pd decreased the membrane fluidity by increasing the trans/cis isomerization ratio (317.7% of control) to enhance the resistance of nZVI. This study underlines the effects of nZVI/Pd on membrane susceptibility via membrane fatty acid transformation during denitrification and suggests the influence of engineered nanomaterials on denitrification. [ABSTRACT FROM AUTHOR]

Hydropower projects have changed the physical habitat of rivers, which has a serious impact on the survival of local fish. The reproduction of fish producing semi-buoyant eggs requires a specific hydrodynamic condition. To predict the influence of cascade hydropower development on the reproductive process of fish with semi-buoyant eggs, a MIKE 21 Flow Model was applied. Lagrangian particle tracking was used to simulate the movement of semi-buoyant eggs and larvae using the Agent-based Modeling (ABM) lab module. The calibrated model showed good agreement between the simulated and observed data for the hydrodynamic process in the reservoir. Twelve scenarios were defined to fully understand whether fish with semi-buoyant eggs can reproduce naturally. The results showed the following: (1) It is difficult to form a fish migration passage in the reservoir in all potential scenarios. (2) Semi-buoyant eggs and larvae sank to the bottom and perished before they hatched and were old enough to survive, since the hydrodynamic conditions could not meet the minimum flow velocity required to keep them in the drift. (3) Even if the hydrodynamic conditions can keep them in the drift in impossible high-discharge conditions, there was not enough drifting time and distance in the reservoir. The results implied that fishes with semi-buoyant eggs cannot reproduce naturally in the main stream, but it is possible that they can reproduce successfully after the protection of the tributary. The method is transferrable to other locations via establishment of models with relevant data to a particular area. Unlabelled Image • It is difficult to form a fish migration passage in the reservoir in all potential scenarios. • Semi-buoyant eggs and larvae sank to the bottom and perished before they hatched and were old enough to survive. • It is possible that fish with semi-buoyant eggs can reproduce successfully after the protection of the tributary. [ABSTRACT FROM AUTHOR]

Abstract The evolution of iron minerals under buried conditions is one of the most important processes controlling the mineral composition and heavy metal transportation in sediments. Microbial-mediated reduction plays a critical role in iron mineral transformation in natural environment. This study examined the transformation pathways of iron minerals mediated by bacteria and the changes of associated arsenic species in iron-rich mine tailings. Static and column reactions were designed to monitor variations of minerals and released iron and arsenic, a reactive transport model was simulated to support laboratory results. Laboratory experiments showed that major ferric minerals were preferentially dissolved and reduced by dissimilatory iron-reducing bacteria. The released Fe3+ in fluid promoted oxidative dissolution of pyrite and arsenopyrite, and precipitation of oxides and carbonates. The arsenic released to fluid was inferred to be immobilized by both pristine ferrihydrite and newly formed hydrous ferric oxides via surface complexation. The reaction system maintained a steady-state of iron mineral transformation and arsenic (im)mobilization. In the latter stage of column reactor experiments, continuous reaction and removal of dissolved Fe3+ and Fe2+ destabilized the state, leading to arsenic re-location and eventually rising concentration in fluid. The findings implicate that microbial-mediated iron mineral evolution remarkably influence the natural mineral assemblages and the fate of contaminant transport in the environment, and that deposition of iron oxides is essential in environmental protection and pollution recovery. Graphical abstract Unlabelled Image Highlights • Advective flow with reductive bacteria in tailings induces Fe-minerals transformation and As transport. • Microbial iron reduction decomposes Fe3+ minerals in oxidized tailings and releases Fe2+ ions. • Jarosite is decomposed while other iron oxides are newly formed in reaction column. • Reactive transport model agrees with lab results of As release, transport and immobilization. [ABSTRACT FROM AUTHOR]

Abstract Awareness of the importance of marine atmosphere for accurately estimating global aerosol budget and climate impacts has arisen recently. However, studies are limited due to the difficulty and inconvenience in sampling as well as the diversity of sources. In this study, the Community Multiscale Air Quality (CMAQ) model was applied to investigate the fine particulate matter (PM 2.5) and its chemical components over the East China Sea (ECS) and offshore regions. In spite of slight under-predictions, model predictions agree well with observations over the ECS and along the coast. PM 2.5 and its major components in the mainland are higher than in marine area, suggesting Asian continent is a major emitter of marine aerosols. PM 2.5 and its components in marine regions show higher abundance during daytime than nighttime, while it is opposite in continental regions. Aerosol phase SO 4 2− is the most abundant component of PM 2.5 over the ECS with an average concentration of 5.12 μg m−3, followed by NH 4 + (1.02 μg m−3) and primary organic aerosol (POA) (0.92 μg m−3). Industry and ship emissions are the top two contributors to primary (PPM) and total PM 2.5 over the ECS, while industry and agriculture sectors are major sources for secondary inorganic aerosols (SIA), followed by ship emissions. For terrestrial regions, industry and agriculture are predominant sources of PM 2.5 and SIA, while industry and residential activities are the top two contributors to PPM. This study improves the understanding of transport and accumulation of air pollutants over the ECS and adjacent regions, and provides useful information for designing efficient control strategies. Graphical abstract Unlabelled Image Highlights • PM 2.5 and components over the East China Sea and offshore regions were investigated. • Model predictions agree well with observations over the ECS and along the coast. • Emissions from China have significant effects on marine aerosols over the ECS. • SO 4 2− is the most abundant PM 2.5 component over the ECS, followed by NH 4 + and POA. • Industry and ship emissions are the top two contributors to total PM 2.5. [ABSTRACT FROM AUTHOR]

The large (26-fold over the past 25 years) increase in the on-road vehicle fleet in China has raised sustainability concerns regarding air pollution prevention, energy conservation, and climate change mitigation. China has established integrated emission control policies and measures since the 1990s, including implementation of emission standards for new vehicles, inspection and maintenance programs for in-use vehicles, improvement in fuel quality, promotion of sustainable transportation and alternative fuel vehicles, and traffic management programs. As a result, emissions of major air pollutants from on-road vehicles in China have peaked and are now declining despite increasing vehicle population. As might be expected, progress in addressing vehicle emissions has not always been smooth and challenges such as the lack of low sulfur fuels, frauds over production conformity and in-use inspection tests, and unreliable retrofit programs have been encountered. Considering the high emission density from vehicles in East China, enhanced vehicle, fuel and transportation strategies will be required to address vehicle emissions in China. We project the total vehicle population in China to reach 400–500 million by 2030. Serious air pollution problems in many cities of China, in particular high ambient PM 2.5 concentration, have led to pressure to accelerate the progress on vehicle emission reduction. A notable example is the draft China 6 emission standard released in May 2016, which contains more stringent emission limits than those in the Euro 6 regulations, and adds a real world emission testing protocol and a 48-h evaporation testing procedure including diurnal and hot soak emissions. A scenario ( PC[1] ) considered in this study suggests that increasingly stringent standards for vehicle emissions could mitigate total vehicle emissions of HC, CO, NO X and PM 2.5 in 2030 by approximately 39%, 57%, 59% and 79%, respectively, compared with 2013 levels. With additional actions to control the future light-duty passenger vehicle population growth and use, and introduce alternative fuels and new energy vehicles, the China total vehicle emissions of HC, CO, NO X and PM 2.5 in 2030 could be reduced by approximately 57%, 71%, 67% and 84%, respectively, (the PC[2] scenario) relative to 2013. This paper provides detailed policy roadmaps and technical options related to these future emission reductions for governmental stakeholders. [ABSTRACT FROM AUTHOR]

As stricter standards for diesel vehicles are implemented in China, and the use of diesel trucks is forbidden in urban areas, determining the contribution of light-duty gasoline vehicles (LDGVs) to on-road PM2.5 emissions in cities is important. Additionally, in terms of particle number and size, particulates emitted from LDGVs have a greater health impact than particulates emitted from diesel vehicles. In this work, we measured PM2.5 emissions from 20 LDGVs in Beijing, using an improved combined on-board emission measurement system. We compared these measurements with those reported in previous studies, and estimated the contribution of LDGVs to on-road PM2.5 emissions in Beijing. The results show that the PM2.5 emission factors for LDGVs, complying with European Emission Standards Euro-0 through Euro-4 were: 117.4±142, 24.1±20.4, 4.85±7.86, 0.99±1.32, 0.17±0.15mg/km, respectively. Our results show a significant decline in emissions with improving vehicle technology. However, this trend is not reflected in recent emission inventory studies. The daytime contributions of LDGVs to PM2.5 emissions on highways, arterials, residential roads, and within urban areas of Beijing were 44%, 62%, 57%, and 57%, respectively. The contribution of LDGVs to PM2.5 emissions varied both for different road types and for different times. [ABSTRACT FROM AUTHOR]

Marine shipping emissions exert important air quality and climate impacts. This study characterized the ambient pollutants predominant by emissions from a variety of marine vessel types near the mid-latitude East China Sea. Two discernible primary shipping emissions were identified by factorization analysis on detailed mass spectra of organic aerosol (OA), as emissions in maneuvering and cruise, highly linked with NO x (and less oxidized OA, black carbon, BC) or CO (and more oxidized OA), respectively. Using radio-recorded quantities and activities of 3566 vessels mixed with slow and high-speed diesel engines, we found emission of NO x or BC per vessel was positively correlated with vessel speed, while CO emission peaked at moderate speed. The approach here based on vessel operation mode directly linked the vessel activities to ambient concentrations of pollutants from marine shipping emission, and may synthesize the complex vessel types in shipping emission inventory. Unlabelled Image • Ambient pollutants were continuously measured along the East China Sea influenced by 3566 marine vessels. • Two primary shipping emissions were identified associated with vessel operation mode in maneuvering or cruise. • Vessels in high speed emitted more black carbon (and NO x), whereas CO emission peaked at moderate speed. • This approach may synthesize the complex vessel types in marine shipping emission inventory. [ABSTRACT FROM AUTHOR]

Agricultural water use is increasing quickly with the rapid socioeconomic development observed in the Wuyuer River basin. Water withdrawal for agriculture over the past decade have seriously depleted the ecological water requirements in the basin and damaged the channel and downstream wetland ecosystems. Achieving sustainable development in the basin will require a balance between agricultural water exploitation and ecological water demands. In this paper, a reservoir and diversion engineering module was integrated with a dualistic distributed hydrological model (WEP model) to investigate the effects of agricultural water use on river discharge. Agricultural water shortages and yearly minimum river discharges between 2020 and 2050 under six agricultural water exploitation scenarios and one natural scenario were estimated based on the proposed model. The results showed that the dualistic hydrological process model was more suitable for basins with agricultural water resource exploitation and that the river discharge was significantly less than the natural discharge due to irrigation and reservoir filling, especially in drought years. Under the scenarios of high, middle and low water resource exploitation without ecological operations, agricultural development was unsustainable because of agricultural water shortages and ecological water scarcity. The evaluation of the guaranteed rates for the agricultural water supply and environmental flows showed that the low water resource exploitation scenario with ecological operations was the best option and that sustainable development could be achieved in the basin under this exploitation scenario in the future. However, implementing water management practices in the basin could result in certain economic losses. These losses could be offset by ecological protection funds for downstream wetlands. Overall, the model results could help to inform planning and investment decisions within the basin to improve the sustainable management of water resources. Unlabelled Image • The dualistic hydrological model is more suitable for agricultural basins. • Reservoir and diversion engineering modules are coupled in the hydrological model. • The model is suited to optimizing management scenarios for decision-making issues. • Environmental fund for wetland can offset losses from the upper and middle reaches. [ABSTRACT FROM AUTHOR]