Fluorochemicals (FCs) are oxidatively recalcitrant, environmentally persistent, and resistant to most conventional treatment technologies. FCs have unique physiochemical properties derived from fluorine which is the most electronegative element. Perfluorooctanesulfonate (PFOS), and perfluorooctanoate (PFOA) have been detected globally in the hydrosphere, atmosphere and biosphere. Reducing treatment technologies such as reverses osmosis, nano-filtration and activated carbon can? remove ?FCs ?from ?water. ?However,? incineration ?of the concentrated waste is required for complete FC destruction. Recently, a number of alternative technologies for FC decomposition have been reported. The FC degradation technologies span a wide range of chemical processes including direct photolysis, photocatalytic oxidation, photochemical oxidation, photochemical reduction, thermally-induced reduction, and sonochemical pyrolysis. This paper reviews these FC degradation technologies in terms of kinetics, mechanism, energetic cost, and applicability. The optimal PFOS/PFOA treatment method is strongly dependent upon the FC concentration, background organic and metal concentration, and available degradation time.
Heavy metals can act as co-selecting agents and promote antibiotic resistance.
Most frequent resistances to heavy metals are observed for zinc and cadmium.
P. aeruginosa and E. coli are commonly resistant to heavy metals and antibiotics.
Heavy metals proliferate antibiotic resistance through co- and cross-resistance.
Heavy metal and antibiotic resistances are common near anthropogenic activities.
Antibiotic resistance in human pathogens can proliferate under selective pressures. Heavy metals in environmental reservoirs may contribute to selecting antibiotic-resistant strains. To determine the associations between heavy metals and antibiotic resistance, a literature review was conducted to systematically collect and categorize evidence for co-occurrence of resistance to heavy metals and antibiotics within human pathogenic bacteria in water, wastewater, and soil. In total, 42 publications adhered to inclusion criteria. Across the reservoirs, zinc and cadmium were the most commonly observed heavy metals associated with resistance to antibiotics. Pseudomonas aeruginosa and Escherichia coli were the most commonly studied bacteria with reported co-occurrence of resistance to several heavy metals and antibiotic classes. As co-selecting agents, prevalence of heavy metals in the environment can proliferate resistance to heavy metals and antibiotics through co-resistance and cross-resistance mechanisms. In comparing different reservoirs, soils and sediments harbor higher heavy metal and antibiotic resistances compared to water environments. Additionally, abiotic factors such as pH can affect the solubility and hence, the availability of heavy metals to bacterial pathogens. Overall, our review demonstrates heavy metals act as co-selecting agents in the proliferation of antibiotic resistance in human pathogens in multiple environmental reservoirs. More studies that include statistical data are needed to further describe the exposure-response relationships between heavy metals and antibiotic resistance in different environmental media. Moreover, integration of culture-based and molecular-based methods in future studies are recommended to better inform our understanding of bacterial co- and cross-resistance mechanisms to heavy metals and antibiotics.
Nanotechnology has revolutionized plethora of scientific and technological fields; environmental safety is no exception. One of the most promising and well-developed environmental applications of nanotechnology has been in water remediation and treatment where different nanomaterials can help purify water through different mechanisms including adsorption of heavy metals and other pollutants, removal and inactivation of pathogens and transformation of toxic materials into less toxic compounds. For this purpose, nanomaterials have been produced in different shapes, integrated into various composites and functionalized with active components. Nanomaterials have also been incorporated in nanostructured catalytic membranes which can in turn help enhance water treatment. In this article, we have provided a succinct review of the most common and popular nanomaterials (titania, carbon nanotubes (CNTs), zero-valent iron, dendrimers and silver nanomaterials) which are currently used in environmental remediation and particularly in water purification. The catalytic properties and functionalities of the mentioned materials have also been discussed.
Catalytic fast pyrolysis (CFP) of Kraft lignins with HZSM-5 zeolite for producing aromatics was investigated using analytical pyrolysis methods. Two Kraft lignins were fast pyrolyzed in the absence and presence of HZSM-5 in a Curie-point pyrolyzer. Without the catalyst, fast pyrolysis of lignin predominantly produced phenols and guaiacols that were derived from the subunits of lignin. However, the presence of HZSM-5 changed the product distribution dramatically. As the SiO2/Al2O3 ratio of HZSM-5 decreased from 200 to 25 and the catalyst-to-lignin ratio increased from 1 to 20, the lignin-derived oxygenates progressively decreased to trace and the aromatics increased substantially. The aromatic yield increased considerably as the pyrolysis temperature increased from 500°C to 650°C, but then decreased with yet further increase of pyrolysis temperature. Under optimal reaction conditions, the aromatic yields were 2.0 wt.% and 5.2 wt.% for the two lignins that had effective hydrogen indexes of 0.08 and 0.35.
Mercury, as a global pollutant, has significant impacts on the environment and human health. The current state of atmospheric mercury emissions, pollution and control in China is comprehensively reviewed in this paper. With about 500–800 t of anthropogenic mercury emissions, China contributes 25%–40% to the global mercury emissions. The dominant mercury emission sources in China are coal combustion, non-ferrous metal smelting, cement production and iron and steel production. The mercury emissions from natural sources in China are equivalent to the anthropogenic mercury emissions. The atmospheric mercury concentration in China is about 2–10 times the background level of North Hemisphere. The mercury deposition fluxes in remote areas in China are usually in the range of 10–50 μg∙m-2∙yr-1. To reduce mercury emissions, legislations have been enacted for power plants, non-ferrous metal smelters and waste incinerators. Currently mercury contented in the flue gas is mainly removed through existing air pollution control devices for sulfur dioxide, nitrogen oxides, and particles. Dedicated mercury control technologies are required in the future to further mitigate the mercury emissions in China.
Fundamentals on the photocatalytic degradation were systematically summarized.
Charge carrier dynamics for the photocatalytic degradation were reviewed.
Adsorption and photodegradation kinetics of reactants were highlighted.
The mechanism aspects, including O2 reduction, reactive oxidation species and key intermediates were also addressed.
Selectivity and stability of semiconductors for photodegradation were clarified.
Heterogeneous photocatalysis has long been considered to be one of the most promising approaches to tackling the myriad environmental issues. However, there are still many challenges for designing efficient and cost-effective photocatalysts and photocatalytic degradation systems for application in practical environmental remediation. In this review, we first systematically introduced the fundamental principles on the photocatalytic pollutant degradation. Then, the important considerations in the design of photocatalytic degradation systems are carefully addressed, including charge carrier dynamics, catalytic selectivity, photocatalyst stability, pollutant adsorption and photodegradation kinetics. Especially, the underlying mechanisms are thoroughly reviewed, including investigation of oxygen reduction properties and identification of reactive oxygen species and key intermediates. This review in environmental photocatalysis may inspire exciting new directions and methods for designing, fabricating and evaluating photocatalytic degradation systems for better environmental remediation and possibly other relevant fields, such as photocatalytic disinfection, water oxidation, and selective organic transformations.
Emissions from manure management are the primary source of GHGs in pig farming.
The effect of pig manure management practises on GHG emissions was assessed.
Recommendations made to standardise units and account for indirect N2O emissions.
AD and compositing should be employed to mitigate GHG emissions in PGM management.
Manure management is the primary source of greenhouse gas (GHG) emissions from pig farming, which in turn accounts for 18% of the total global GHG emissions from the livestock industry. In this review, GHG emissions (N2O and CH4 emissions in particular) from individual pig manure (PGM) management practices (European practises in particular) are systematically analyzed and discussed. These manure management practices include manure storage, land application, solid/liquid separation, anaerobic digestion, composting and aerobic wastewater treatment. The potential reduction in net GHG emissions by changing and optimising these techniques is assessed. This review also identifies key research gaps in the literature including the effect of straw covering of liquid PGM storages, the effect of solid/liquid separation, and the effect of dry anaerobic digestion on net GHG emissions from PGM management. In addition to identifying these research gaps, several recommendations including the need to standardize units used to report GHG emissions, to account for indirect N2O emissions, and to include a broader research scope by conducting detailed life cycle assessment are also discussed. Overall, anaerobic digestion and compositing to liquid and solid fractions are best PGM management practices with respect to their high GHG mitigation potential.
Screening plants that are hypertolerant to and excluders of certain heavy metals plays a fundamental role in a remediation strategy for metalliferous mine tailings. A field survey of terrestrial higher plants growing on Mn mine tailings at Huayuan, Hunan Province, China was conducted to identify candidate species for application in phytostabilization of the tailings in this region. In total, 51 species belonging to 21 families were recorded and the 12 dominant plants were investigated for their potential in phytostabilization of heavy metals. Eight plant species, Alternanthera philoxeroides, Artemisia princeps, Bidens frondosa, Bidens pilosa, Cynodon dactylon, Digitaria sanguinalis, Erigeron canadensis, and Setaria plicata accumulated much lower concentrations of heavy metals in shoots and roots than the associated soils and bioconcentration factors (BFs) for Cd, Mn, Pb and Zn were all<1, demonstrating a high tolerance to heavy metals and poor metals translocation ability. The field investigation also found that these species grew fast, accumulated biomass rapidly and developed a vegetation cover in a relatively short time. Therefore, they are good candidates for phytostabilization purposes and could be used as pioneer species in phytoremediation of Mn mine tailings in this region of South China.
Distribution and behavior of arsenic in wetland are summarized.
Macro-scale and micro-scale processes in wetland are reviewed.
Microbes act as the switch in determining wetland as a source or sink of arsenic.
Environmental factors affecting arsenic microbial biotransformation are summarized.
Arsenic (As) is a pervasive environmental toxin and carcinogenic metalloid. It ranks at the top of the US priority List of Hazardous Substances and causes worldwide human health problems. Wetlands, including natural and artificial ecosystems (i.e. paddy soils) are highly susceptible to As enrichment; acting not only as repositories for water but a host of other elemental/chemical moieties. While macro-scale processes (physical and geological) supply As to wetlands, it is the micro-scale biogeochemistry that regulates the fluxes of As and other trace elements from the semi-terrestrial to neighboring plant/aquatic/atmospheric compartments. Among these fine-scale events, microbial mediated As biotransformations contribute most to the element’s changing forms, acting as the ‘switch’ in defining a wetland as either a source or sink of As. Much of our understanding of these important microbial catalyzed reactions follows relatively recent scientific discoveries. Here we document some of these key advances, with focuses on the implications that wetlands and their microbial mediated transformation pathways have on the global As cycle, the chemistries of microbial mediated As oxidation, reduction and methylation, and future research priorities areas.
Rapidly increasing concentration of CO2 in the atmosphere has drawn more and more attention in recent years, and adsorption has been considered as an effective technology for CO2 capture from the anthropogenic sources. In this paper, the attractive adsorbents including activated carbons and amine-modified materials were mainly reviewed and discussed with particular attention on progress in the adsorbent preparation and CO2 adsorption capacity. Carbon materials can be prepared from different precursors including fossil fuels, biomass and resins using the carbonization-activation or only activation process, and activated carbons prepared by KOH activation with high CO2 adsorbed amount were reviewed in the preparation, adsorption capacity as well as the relationship between the pore characteristics and CO2 adsorption. For the amine-modified materials, the physical impregnation and chemical graft of polyethylenimine (PEI) on the different porous materials were introduced in terms of preparation method and adsorption performance as well as their advantages and disadvantages for CO2 adsorption. In the last section, the issues and prospect of solid adsorbents for CO2 adsorption were summarized, and it is expected that this review will be helpful for the fundamental studies and industrial applications of activated carbons and amine-modified adsorbents for CO2 capture.
A sediment microbial fuel cell (SMFC) with three dimensional floating biocathode (FBC) was developed for the electricity generation and biodegradation of sediment organic matter in order to avoid negative effect of dissolved oxygen (DO) depletion in aqueous environments on cathode performance and search cost-effective cathode materials. The biocathode was made from graphite granules with microbial attachment to replace platinum (Pt)-coated carbon paper cathode in a laboratory-scale SMFC (3 L in volume) filled with river sediment (organic content 49±4 g·kg-1 dry weight). After start-up of 10 days, the maximum power density of 1.00W·m-3 (based on anode volume) was achieved. The biocathode was better than carbon paper cathode catalyzed by Pt. The attached biofilm on cathode enhanced power generation significantly. The FBC enhanced SMFC performance further in the presence aeration. The SMFC was continuously operated for an over 120-day period. Power generation peaked within 24 days, declined gradually and stabilized at a level of 1/6 peak power output. At the end, the sediment organic matter content near the anode was removed by 29% and the total electricity generated was equal to 0.251 g of chemical oxygen demand (COD) removed.
O3 increment is mainly caused by changes in meteorology rather than emissions.
Emission reduction is effective to reduce O3 nationwide, especially in summer.
Strengthened NOx controls are necessary to meet the ambient O3 standard.
We have quantified the impacts of anthropogenic emissions reductions caused by the Air Pollution Control Action Plan and changes in meteorological fields between 2013 and 2017 on the warm-season O3 concentration in China using a regional 3D chemical transport model. We found that the impact on daily maximum eight-hour (MDA8) O3 concentration by the meteorological variation that mostly increased O3 was greater than that from emission reduction, which decreased O3. Specifically, the control measures implemented since 2013 in China have reduced SO2, NOx, PM2.5, and VOC emissions by 33%, 25%, 30%, and 4% in 2017, while NH3 emissions have increased by 7%. The changes in anthropogenic emissions lowered MDA8 O3 by 0.4–3.7 ppb (0.8%–7.6%, varying by region and month), although MDA8 O3 was increased slightly in some urban areas (i.e. North China) at the beginning/end of warm seasons. Relative to 2013, the average 2 m temperature in 2017 shows increments in North, North-east, East, and South China (0.34℃–0.83℃) and decreases in Central China (0.24℃). The average solar radiation shows increments in North, North-east, and South China (7.0–9.7 w/m2) and decreases in Central, South-west, and North-west China (4.7–10.3 w/m2). The meteorological differences significantly change MDA8 O3 by -3.5–8.5 ppb (-8.2%–18.8%) with large temporal variations. The average MDA8 O3 was slightly increased in North, North-east, East, and South China. The response surface model suggests that the O3 formation regime transfers from NOx-saturated in April to NOx-limited in July on average in China.
Small- and medium-sized enterprises (SMEs) play an important role in sustainable development not only for their significant contribution to China’s economy, but also for their big share of total discharged pollutants. Therefore, this research takes the enterprises in Suzhou Industrial Park, China as the case study to investigate the environmental management practices of SMEs, and identify drivers and barriers to engaging businesses in environmental management initiatives. It is shown that, as in other countries, SMEs are less active in adopting environmental management initiatives than larger companies. Legislation remains the key driver to engage SMEs in environmental management initiatives. Based on the analysis, policy recommendations are also presented.
China is at present experiencing a very rapid urbanization process, which has brought a number of adverse impacts upon the water environment. In particular, urban runoff quantity and quality control have emerged as one of the key concerns for municipal officials. One of the strategies being considered is the use of a Low Impact Development type of Best Management Practices (LID BMPs) for urban storm water runoff quantity and quality control. In this paper, the situation surrounding urban runoff control in China is reviewed first. Then the conventional strategy and technologies for the construction and management of urban drainage systems are discussed, while exploring their inherent dilemmas. The LID BMPs are then introduced to control urban runoff in the context of urban sustainable water systems. After the comprehensive analysis of the various LID BMPs, the advances in LID BMPs research and practice for urban runoff control in China are investigated and summarized. At last, the difficulties of implementing LID BMPs in China are discussed, and a direction for the future is proposed.
• BiVO4/Fe3O4/rGO has excellent photocatalytic activity under solar light radiation.
• It can be easily separated and collected from water in an external magnetic field.
• BiVO4/Fe3O4/0.5% rGO exhibited the highest RhB removal efficiency of over 99%.
• Hole (h+) and superoxide radical (O2•−) dominate RhB photo-decomposition process.
• The reusability of this composite was confirmed by five successive recycling runs.
Fabrication of easily recyclable photocatalyst with excellent photocatalytic activity for degradation of organic pollutants in wastewater is highly desirable for practical application. In this study, a novel ternary magnetic photocatalyst BiVO4/Fe3O4/reduced graphene oxide (BiVO4/Fe3O4/rGO) was synthesized via a facile hydrothermal strategy. The BiVO4/Fe3O4 with 0.5 wt% of rGO (BiVO4/Fe3O4/0.5% rGO) exhibited superior activity, degrading greater than 99% Rhodamine B (RhB) after 120 min solar light radiation. The surface morphology and chemical composition of BiVO4/Fe3O4/rGO were studied by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–visible diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. The free radicals scavenging experiments demonstrated that hole (h+) and superoxide radical (O2•−) were the dominant species for RhB degradation over BiVO4/Fe3O4/rGO under solar light. The reusability of this composite catalyst was also investigated after five successive runs under an external magnetic field. The BiVO4/Fe3O4/rGO composite was easily separated, and the recycled catalyst retained high photocatalytic activity. This study demonstrates that catalyst BiVO4/Fe3O4/rGO possessed high dye removal efficiency in water treatment with excellent recyclability from water after use. The current study provides a possibility for more practical and sustainable photocatalytic process.
Antibiotic-resistant bacteria and antibiotic resistance genes are in water bodies.
UV/chlorination method is better to remove ARGs than UV or chlorination alone.
Research on UV/hydrogen peroxide to eliminate ARGs is forthcoming.
UV-based photocatalytic processes are effective to degrade ARGs.
Antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) have been recognized as one of the biggest public health issues of the 21st century. Both ARB and ARGs have been determined in water after treatment with conventional disinfectants. Ultraviolet (UV) technology has been seen growth in application to disinfect the water. However, UV method alone is not adequate to degrade ARGs in water. Researchers are investigating the combination of UV with other oxidants (chlorine, hydrogen peroxide (H2O2), peroxymonosulfate (PMS), and photocatalysts) to harness the high reactivity of produced reactive species (Cl·, ClO·, Cl2·−, ·OH, and SO4·−) in such processes with constituents of cell (e.g., deoxyribonucleic acid (DNA) and its components) in order to increase the degradation efficiency of ARGs. This paper briefly reviews the current status of different UV-based treatments (UV/chlorination, UV/H2O2, UV/PMS, and UV-photocatalysis) to degrade ARGs and to control horizontal gene transfer (HGT) in water. The review also provides discussion on the mechanism of degradation of ARGs and application of q-PCR and gel electrophoresis to obtain insights of the fate of ARGs during UV-based treatment processes.
The concept design and detailed information of the SORPES station are introduced.
Main scientific findings based 5-year measurements at the station are summarized.
The future outlook of the development plan and its implications are discussed.
The results improved understanding of interaction of physical and chemical processes.
More SORPES-type stations are need to in different regions in China and the world.
This work presents an overall introduction to the Station for Observing Regional Processes of the Earth System – SORPES in Nanjing, East China, and gives an overview about main scientific findings in studies of air pollution-weather/climate interactions obtained since 2011. The main results summarized in this paper include overall characteristics of trace gases and aerosols, chemical transformation mechanisms for secondary pollutants like O3, HONO and secondary inorganic aerosols, and the air pollution – weather/climate interactions and feedbacks in mixed air pollution plumes from sources like fossil fuel combustion, biomass burning and dust storms. The future outlook of the development plan on instrumentation, networking and data-sharing for the SORPES station is also discussed.
The role of water security in sustainable development and in the nexus of water, food, energy and climate interactions is examined from the starting point of the definition of water security offered by Grey and Sadoff. Much about the notion of security has to do with the presumption of scarcity in the resources required to meet human needs. The treatment of scarcity in mainstream economics is in turn examined, therefore, in relation to how each of us as individuals reconciles means with ends, a procedure at the core of the idea of sustainable development. According to the Grey-Sadoff definition, attaining water security amounts to achieving basic, single-sector water development as a precursor of more general, self-sustaining, multi-sectoral development. This is consistent with the way in which water is treated as “first among equals”, i.e. privileged, in thinking about what is key in achieving security around the nexus of water, food, energy and climate. Cities, of course, are locations where demands for these multiple resource-energy flows are increasingly being generated. The paper discusses two important facets of security, i.e., diversity of access to resources and services (such as sanitation) and resilience in the behavior of coupled human-built-natural systems. Eight quasi-operational principles, by which to gauge nexus security with respect to city buildings and infrastructure, are developed.
• Byproduct formation mechanisms during electrochemical oxidation water treatment.
• Control byproduct formation by quenchers.
• Process optimization to suppress byproduct formation.
Electrochemical oxidation (EO) is a promising technique for decentralized wastewater treatment, owing to its modular design, high efficiency, and ease of automation and transportation. The catalytic destruction of recalcitrant, non-biodegradable pollutants (per- and poly-fluoroalkyl substances (PFAS), pharmaceuticals, and personal care products (PPCPs), pesticides, etc.) is an appropriate niche for EO. EO can be more effective than homogeneous advanced oxidation processes for the degradation of recalcitrant chemicals inert to radical-mediated oxidation, because the potential of the anode can be made much higher than that of hydroxyl radicals (EOH = 2.7 V vs. NHE), forcing the direct transfer of electrons from pollutants to electrodes. Unfortunately, at such high anodic potential, chloride ions, which are ubiquitous in natural water systems, will be readily oxidized to chlorine and perchlorate. Perchlorate is a to-be-regulated byproduct, and chlorine can react with matrix organics to produce organic halogen compounds. In the past ten years, novel electrode materials and processes have been developed. However, spotlights were rarely focused on the control of byproduct formation during EO processes in a real-world context. When we use EO techniques to eliminate target contaminants with concentrations at μg/L-levels, byproducts at mg/L-levels might be produced. Is it a good trade-off? Is it possible to inhibit byproduct formation without compromising the performance of EO? In this mini-review, we will summarize the recent advances and provide perspectives to address the above questions.
● A novel VMD-IGOA-LSTM model has proposed for the prediction of water quality.
● Improved model quickly converges to the global optimal fitness and remains stable.
● The prediction accuracy of water quality parameters is significantly improved.
Water quality prediction is vital for solving water pollution and protecting the water environment. In terms of the characteristics of nonlinearity, instability, and randomness of water quality parameters, a short-term water quality prediction model was proposed based on variational mode decomposition (VMD) and improved grasshopper optimization algorithm (IGOA), so as to optimize long short-term memory neural network (LSTM). First, VMD was adopted to decompose the water quality data into a series of relatively stable components, with the aim to reduce the instability of the original data and increase the predictability, then each component was input into the IGOA-LSTM model for prediction. Finally, each component was added to obtain the predicted values. In this study, the monitoring data from Dayangzhou Station and Shengmi Station of the Ganjiang River was used for training and prediction. The experimental results showed that the prediction accuracy of the VMD-IGOA-LSTM model proposed was higher than that of the integrated model of Ensemble Empirical Mode Decomposition (EEMD), the integrated model of Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN), Nonlinear Autoregressive Network with Exogenous Inputs (NARX), Recurrent Neural Network (RNN), as well as other models, showing better performance in short-term prediction. The current study will provide a reliable solution for water quality prediction studies in other areas.
The fate and removal of pharmaceuticals and personal care products (PPCPs) in wastewater treatment plants (WWTPs) has received great attention during the last decade. Numerous data concerning concentrations in the water phase can be found in the literature, however corresponding data from sludge as well as associated mass balance calculations are very limited. In the present study, the adsorbed and dissolved concentrations of 9 PPCPs were investigated in each unit of a WWTP in Beijing, China. Based on the calculation of mass balance, the relative mass distribution and removal efficiency of each target compound was obtained at each process. The amount of PPCPs entering into the WWTP ranged from 12 g·d−1 to 3848 g·d−1. Five target compounds (caffeine, chloramphenicol, bezafibrate, clofibric acid, and N,N-diethyl-meta-toluamide) were effectively removed, with rates of 57%–100%. Negative removal efficiencies were obtained for sulpiride, metoprolol, nalidixic acid, and carbamazepine, ranging from -19% to -79%. PPCPs mainly existed in dissolved form (≥92%) in both the raw influent and the final effluent. The sludge cake carried a much lower amount of PPCPs (17 g·d−1) compared with the discharged effluent (402 g·d−1). In A2/O treatment tanks, the anaerobic and anoxic tanks showed good performance for PPCPs removal, and the amount of adsorbed PPCPs was increased. The results reveal that both the dissolved and the adsorbed phases should be considered when assessing the removal capacity of each A2/O tank.
We develop a multi-effect evaluation method to assess integrated impact of VOCs.
Enable policy-makers to identify important emission sources, regions, and key species.
Solvent usage and industrial process are the most important anthropogenic sources.
Styrene, toluene, ethylene, benzene, and m/p-xylene are key species to be cut.
Volatile organic compounds (VOCs) play important roles in the atmosphere via three main pathways: photochemical ozone formation, secondary organic aerosol production, and direct toxicity to humans. Few studies have integrated these effects to prioritize control measures for VOCs sources. In this study, we developed a multi-effects evaluation methodology based on updated emission inventories and source profiles, by combining the ozone formation potential (OFP), secondary organic aerosol potential (SOAP), and VOC toxicity data. We derived species-specific emission inventories for 152 sources. The OFPs, SOAPs, and toxicity of each source were estimated, the contribution and sharing of source to each of these adverse effects were calculated. Weightings were given to the three adverse effects by expert scoring, and then the integrated effect was determined. Taking 2012 as the base year, solvent use and industrial process were found to be the most important anthropogenic sources, accounting for 24.2% and 23.1% of the integrated effect, respectively, followed by biomass burning, transportation, and fossil fuel combustion, each had a similar contribution ranging from 16.7% to 18.6%. The top five industrial sources, including plastic products, rubber products, chemical fiber products, the chemical industry, and oil refining, accounted for nearly 70.0% of industrial emissions. Beijing, Chongqing, Shanghai, Jiangsu, and Guangdong were the five provinces contributing the largest integrated effects. For the VOC species from emissions showed the largest contributions were styrene, toluene, ethylene, benzene, and m/p-xylene.
It is well established that ambient particles in the size range of 2.5 microns or less case a wide variety of adverse health effects. According to a recent study from the World Health Organization, in 2010 these effects resulted in approximately 3.2 million premature deaths with vehicles being one of the significant contributors. Diesel vehicle particulate emissions which are virtually all smaller than 2.5 microns raise additional special concerns due to their carcinogenicity and high ratio of black carbon (BC) to organic carbon; black carbon has recently been found to be the second most important contributor to climate change after carbon dioxide. Other pollutants emitted by diesels and other vehicles such as the oxides of nitrogen and volatile organic compounds also contribute to ambient particulate matter smaller than 2.5 microns in size (PM2.5) after undergoing secondary transformations in the atmosphere. Technologies have been developed that can dramatically reduce vehicle emissions when clean, low sulfur fuels are available and these technologies are being phased in throughout the industrialized world resulting in a global decrease in particulate matter (PM) and BC emissions from vehicles. However the vehicle population is growing rapidly in the developing world, leading to increases in emissions in many countries. Unless these rapidly industrializing countries move to state of the art vehicles and clean fuels, global PM, BC and NOx emissions from road vehicles will start to turn up over the next 10 to 15 years.
It is essential to determine the heavy metal concentrations in sewage sludge to select appropriate disposal methods. We conducted a national survey of heavy metal concentrations of sewage sludge samples from 107 municipal sewage treatment plants located in 48 cities covering the 31 provinces and autonomous regions, as well as Hong Kong, Macao and Taiwan by Xinjiang Production and Construction Corps in 2006, and identified the temporal trends of heavy metal contents in sewage sludge by comparison with surveys conducted in 1994–2001. In 2006, the average concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in sewage sludge were 20.2, 1.97, 93.1, 218.8, 2.13, 48.7, 72.3, and 1058 mg·kg-1, respectively. Because of the decreased discharge of heavy metals into industrial wastewater in China and the increasingly stringent regulations governing the content of industrial wastes entering sewers, the average concentrations of Cd, Cr, Cu, Hg, Ni, Pb, and Zn have decreased by 32.3%, 49.7%, 54.9%, 25.0%, 37.2%, 44.8%, and 27.0%, respectively, during the past 12 years. The concentrations of Cd, Cr, Cu, Ni, and Zn in the samples exceeded the heavy metal limits of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant in China (GB 18918-2002) by 6.5%, 3.7%, 6.5%, 6.5%, and 11.2%, respectively. From these results, 85 of the 107 municipal sludges analyzed would be considered suitable for land application.