Frontiers of Environmental Science & Engineering

About the Journal

Journal Metrics

ISSN 2095-2201 (Print)
ISSN 2095-221X (Online)
CN 10-1013/X
Postal Subscription Code 80-973
Formerly Known as Frontiers of Environmental Science & Engineering in China
2019 Impact Factor: 4.053
30 Most Downloaded Articles
Published in last 1 year | In last 2 years| In last 3 years| All| Most Downloaded in Recent Month | Most Downloaded in Recent Year|

All
Please wait a minute...
For Selected: View Abstracts Toggle Thumbnails
Municipal wastewater treatment in China: Development history and future perspectives Collection
Jiuhui Qu, Hongchen Wang, Kaijun Wang, Gang Yu, Bing Ke, Han-Qing Yu, Hongqiang Ren, Xingcan Zheng, Ji Li, Wen-Wei Li, Song Gao, Hui Gong
Front. Environ. Sci. Eng..  2019, 13 (6): 88.   https://doi.org/10.1007/s11783-019-1172-x
Abstract   HTML   PDF (1489KB)

The history of China’s municipal wastewater management is revisited.

The remaining challenges in wastewater sector in China are identified.

New concept municipal wastewater treatment plants are highlighted.

An integrated plant of energy, water and fertilizer recovery is envisaged.

China has the world’s largest and still growing wastewater sector and water market, thus its future development will have profound influence on the world. The high-speed development of China’s wastewater sector over the past 40 years has forged its global leading treatment capacity and innovation ability. However, many problems were left behind, including underdeveloped sewers and sludge disposal facilities, low sustainability of the treatment processes, questionable wastewater treatment plant (WWTP) effluent discharge standards, and lacking global thinking on harmonious development between wastewater management, human society and the nature. Addressing these challenges calls for fundamental changes in target design, policy and technologies. In this mini-review, we revisit the development history of China’s municipal wastewater management and identify the remaining challenges. Also, we highlight the future needs of sustainable development and exploring China’s own wastewater management path, and outlook the future from several aspects including targets of wastewater management, policies and technologies, especially the new concept WWTP. Furthermore, we envisage the establishment of new-generation WWTPs with the vision of turning WWTP from a site of pollutant removal into a plant of energy, water and fertilizer recovery and an integrated part urban ecology in China.

Table and Figures | Reference | Related Articles | Metrics
Cited: WebOfScience(18)
A syntrophic propionate-oxidizing microflora and its bioaugmentation on anaerobic wastewater treatment for enhancing methane production and COD removal
Chong Liu, Jianzheng Li, Shuo Wang, Loring Nies
Front. Environ. Sci. Eng..  2016, 10 (4): 13.   https://doi.org/10.1007/s11783-016-0856-8
Abstract   HTML   PDF (422KB)

Syntrophic propionate-oxidizing microflora B83 was enriched from anaerobic sludge.

The bioaugmentation of microflora B83 were evaluated from wastewater treatment.

Methane yield and COD removal were enhanced by bioaugmentation of microflora B83.

Hydrogen-producing acetogensis was a rate-limiting step in methane fermentation.

Methane fermentation process can be restricted and even destroyed by the accumulation of propionate because it is the most difficult to be anaerobically oxidized among the volatile fatty acids produced by acetogenesis. To enhance anaerobic wastewater treatment process for methane production and COD removal, a syntrophic propionate-oxidizing microflora B83 was obtained from an anaerobic activated sludge by enrichment with propionate. The inoculation of microflora B83, with a 1:9 ratio of bacteria number to that of the activated sludge, could enhance the methane production from glucose by 2.5 times. With the same inoculation dosage of the microflora B83, COD removal in organic wastewater treatment process was improved from 75.6% to 86.6%, while the specific methane production by COD removal was increased by 2.7 times. Hydrogen-producing acetogenesis appeared to be a rate-limiting step in methane fermentation, and the enhancement of hydrogen-producing acetogens in the anaerobic wastewater treatment process had improved not only the hydrogen-producing acetogenesis but also the acidogenesis and methanogenesis.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(5) WebOfScience(27)
Is there an inverted U-shaped curve? Empirical analysis of the Environmental Kuznets Curve in agrochemicals
Fei LI,Suocheng DONG,Fujia LI,Libiao YANG
Front. Environ. Sci. Eng..  2016, 10 (2): 276-287.   https://doi.org/10.1007/s11783-014-0700-y
Abstract   HTML   PDF (285KB)

As the largest contributor to water impairment, agriculture-related pollution has attracted the attention of scientists as well as policy makers, and quantitative information is being sought to focus and advance the policy debate. This study applies the panel unit root, heterogeneous panel cointegration, and panel-based dynamic ordinary least squares to investigate the Environmental Kuznets Curve on environmental issues resulting from use of agricultural synthetic fertilizer, pesticide, and film for 31 provincial economies in mainland China from 1989 to 2009. The empirical results indicate a positive long-run co-integrated relationship between the environmental index and real GDP per capita. This relationship takes on the inverted U-shaped Environmental Kuznets Curve, and the value of the turning point is approximately 10,000–13,000, 85,000–89,000 and over 160,000 CNY, for synthetic fertilizer nitrogen indicator, fertilizer phosphorus indicator and pesticide indicator, respectively. At present, China is subject to tremendous environmental pressure and should assign more importance to special agriculture-related environmental issues.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(10) WebOfScience(14)
Pyrolysis behaviors of oil sludge based on TG/FTIR and PY-GC/MS
Wei SONG, Jianguo LIU, Yongfeng NIE,
Front.Environ.Sci.Eng..  2010, 4 (1): 59-64.   https://doi.org/10.1007/s11783-009-0152-y
Abstract   PDF (129KB)
Pyrolysis is an alternative technology for oil sludge treatment. Thermogravimetric Analysis-Fourier Transform Infrared Spectroscopy and Pyrolysis-Gas Chromatography/Mass Spectrometry were employed to investigate the pyrolysis process and products of oil sludge. The pyrolysis process was divided into five stages: drying and gas desorption, oil volatilization, main pyrolysis, semi-coke charring, and mineral decomposition. The main reaction temperatures ranged from 497.6 K to 753.2 K. The products were mainly composed of pairs of alkane and alkene (carbon number ranges from 1 to 27). The mechanisms consisted of random chain scission followed by end chain scission at high temperatures with volatilization occurring during the whole process. This study is useful not only for the proper design of a pyrolysis system, but also for improving the utilization of liquid oil products.
Reference | Related Articles | Metrics
Cited: WebOfScience(1)
Upgrading to urban water system 3.0 through sponge city construction Collection
Nanqi Ren, Qian Wang, Qiuru Wang, Hong Huang, Xiuheng Wang
Front. Environ. Sci. Eng..  2017, 11 (4): 9.   https://doi.org/10.1007/s11783-017-0960-4
Abstract   HTML   PDF (220KB)

Cities in China confront full-scale and serious water crises due to urbanization.

System 2.0 with fragmented gray engineering measures showed inadaptability.

A novel water-cycling system is developed to systematically solve water crises.

Multi-purpose system 3.0 with integrated strategy shows powerful vitality.

Urban water system 3.0 (Blue, gray, brown and yellow arrows represent water flow, wastewater flow, resource and energy respectively)

Facing the pressure of excessive water consumption, high pollution load and rainstorm waterlogging, linear and centralized urban water system, system 2.0, as well as traditional governance measures gradually exposed characters of water-sensitivity, vulnerability and unsustainability, subsequently resulting in a full-blown crisis of water shortage, water pollution and waterlogging. To systematically relieve such crisis, we established healthy urban water-cycling system 3.0, in which decentralized sewerage systems, spongy infrastructures and ecological rivers play critical roles. Through unconventional water resource recycling, whole process control of pollutions and ecological restoration, system 3.0 with integrated management measures, is expected to fit for multiple purposes which involve environmental, ecological, economic and social benefits. With advantages of flexibility, resilience and sustainability, water system 3.0 will show an increasingly powerful vitality in the near future.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(18) WebOfScience(20)
Soil enzyme activities and their indication for fertility of urban forest soil
SHAN Qihua, YU Yuanchun, ZHANG Jinchi, YU Jian
Front.Environ.Sci.Eng..  2008, 2 (2): 218-223.   https://doi.org/10.1007/s11783-008-0037-5
Abstract   HTML   PDF (93KB)
To reveal the biological characteristics of urban forest soil and the effects of soil enzyme on soil fertility as well as the correlation between physicochemical properties and enzyme activities, 44 urban forest soil profiles in Nanjing were investigated. Basic soil physicochemical properties and enzyme activities were analyzed in the laboratory. Hydrogen peroxidase, dehydrogenase, alkaline phosphatase, and cellulase were determined by potassium permanganate titration, TTC (C19H15N4·Cl) colorimetry, phenyl phosphate dinatrium colorimetry, and anthrone colorimetry, respectively. The result showed that soil pH, organic carbon (C), and total nitrogen (N) had great effects on hydrogen peroxidase, dehydrogenase, and alkaline phosphatase activities in 0–20 cm thick soil. However, pH only had great effect on hydrogen peroxidase, dehydrogenase, and alkaline phosphatase activities in 20–40 cm thick soil. Hydrogen peroxidase, dehydrogenase, and alkaline phosphatase were important biological indicators for the fertility of urban forest soil. Both in 0–20 cm and 20–40 cm soil, soil enzyme system (hydrogen peroxidase, dehydrogenase, alkaline phosphatase, and cellulase) had a close relationship with a combination of physicochemical indicators (pH, organic C, total N, available K, available P, cation exchange capacity (CEC), and microbial biomass carbon (Cmic)). The more soil enzyme activities there were, the higher the fertility of urban forest soil.
Reference | Related Articles | Metrics
Cited: Crossref(7)
Space view of the decadal variation for typical air pollutants in the Pearl River Delta (PRD) region in China Collection
Zifeng WANG, Min SHAO, Liangfu CHEN, Minghui TAO, Liuju ZHONG, Duohong CHEN, Meng FAN, Yang WANG, Xinhui WANG
Front. Environ. Sci. Eng..  2016, 10 (5): 9.   https://doi.org/10.1007/s11783-016-0853-y
Abstract   HTML   PDF (3907KB)

Spatial and temporal trends of the typical pollutants in PRD viewed from space.

Comparisons of the satellite retrievals with the collocated in situ data are given.

Among different MCs, the control measures applied in PRD are the most effective.

The unique HCHO trends imply significant contribution from the biogenic origins.

The Pearl River Delta (PRD) is one of the most industrialized, urbanized and populated regions in China, and thus has been long suffering from severe air pollutions. Space data provide a unique perspective for investigating the atmospheric environment at a regional scale. By utilizing multiple satellite retrievals from 2005 to 2013, this study presented, for the first time, the spatial patterns and temporal trends of typical air pollutants over PRD and its vicinity. As viewed from space, aerosol optical depth (AOD), NO2 and SO2 all had their higher values at the central part of PRD, and showed clear descending gradients as moving to the outskirt of this region. As to the inter-annual variation, all these pollutants had decreasing trends in PRD during the study period, which generally agreed with the relevant in situ measurements. However, the satellite retrievals differed from ground measurements when addressing NO2 and SO2 in the vicinity of PRD. This work also provides the inter-comparison among PRD and three other metropolitan clusters in China: PRD had relatively high AOD, moderate NO2 and low SO2 levels, and it was the only region achieving the effective reduction of NO2 and SO2 during last decade. Unlike the previous three pollutants, HCHO observed by satellite showed very special patterns: it had a relatively homogeneous spatial distribution over both of PRD and its vicinity, and presented an opposite increasing trend from 2005 to 2010. Moreover, PRD had the highest HCHO level among all the metropolitan clusters, hinting a considerable contribution of biogenic origins of HCHO in PRD.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(8) WebOfScience(16)
Environment and economic feasibility of municipal solid waste central sorting strategy: a case study in Beijing
Hua ZHANG, Zongguo WEN, Yixi CHEN
Front. Environ. Sci. Eng..  2016, 10 (4): 10.   https://doi.org/10.1007/s11783-016-0852-z
Abstract   HTML   PDF (904KB)

The Green House program reduced the amount of waste by 34%.

The Green House is now running with a monthly loss of 1982 CNY.

Involve government, expand scale, use professional technology are main suggestions.

Improved program can reduce the amount of waste by 37% (33.8 tons monthly).

Improved program can flip the loss into a profit worth 35034 CNY monthly.

Although Beijing has carried out municipal solid waste (MSW) source separation since 1996, it has largely been ineffective. In 2012, a “Green House” program was established as a new attempt for central sorting. In this study, the authors used material flow analysis (MFA) and cost benefit analysis (CBA) methods to investigate Green House’s environment and economic feasibility. Results showed that the program did have significant environmental benefits on waste reduction, which reduced the amount of waste by 34%. If the Green House program is implemented in a residential community with wet waste ratio of 66%, the proportion of waste reduction can reach 37%. However, the Green House is now running with a monthly loss of 1982 CNY. This is mainly because most of its benefits come from waste reduction (i.e., 5878 CNY per month), which does not turn a monetary benefit, but is instead distributed to the whole of society as positive environmental externalities. Lack of government involvement, small program scale, and technical/managerial deficiency are three main barriers of the Green House. We, thus, make three recommendations: involve government authority and financial support, expand the program scale to separate 91.4 tons of waste every month, and use more professional equipment/technologies. If the Green House program can successfully adopt these suggestions, 33.8 tons of waste can be reduced monthly, and it would be able to flip the loss into a profit worth 35034 CNY.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(8) WebOfScience(28)
Effects of phosphorus concentration on Cr(VI) sorption onto phosphorus-rich sludge biochar
DING Wenchuan,PENG Wenlong,ZENG Xiaolan,TIAN Xiumei
Front.Environ.Sci.Eng..  2014, 8 (3): 379-385.   https://doi.org/10.1007/s11783-013-0606-0
Abstract   HTML   PDF (190KB)

To investigate effects of phosphorus content on Cr(VI) sorption onto phosphorus-rich biochar, sewage sludge of different phosphorus concentrations from 4 to 60 mg·g-1 by dry weight were prepared and carbonized to make biochar for batch sorption experiments. Test results revealed that different phosphorous concentration of raw sludge had respective impacts on surface area, pore surface area, average pore diameter and pH value of derived biochar. The adsorption kinetics of phosphorus-rich biochar could be described by the pseudo-second-order model. The sorption isotherm data followed Langmiur model better than Freundlich model. Biochar produced from sludge with phosphorus concentration of 20 mg·g-1 gave the largest chromium sorption capacity, which could be attributed to its largest surface area and pores surface area comparing with those of biochars from sludge with other phosphorus concentrations. The chromium loaded biochar was analyzed using Fourier Transform Infrared Spectroscopy and X-ray Diffraction measurement. The results indicated that chemical functional groups hydroxyl and methyl on surface of biochar were involved in Cr(VI) binding and its reducing to Cr(III). Then, a portion of Cr(III) in form of various phosphate precipitates was bound onto biochar surface and the rest was released into the solution. The experimental results suggested that phosphorus played an important role in pore and surface area development of sludge biochar during pyrolytic process. It also could react with Cr(III) on the biochar surface that impacted on capacity of Cr(VI) removal from solution by sludge biochar. Therefore, phosphorus concentration in sludge should be considered when sludge pyrolytic residue would be reused for heavy metals sorbing.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(7) WebOfScience(8)
Engineering application of membrane bioreactor for wastewater treatment in China: Current state and future prospect
Kang XIAO, Ying XU, Shuai LIANG, Ting LEI, Jianyu SUN, Xianghua WEN, Hongxun ZHANG, Chunsheng CHEN, Xia HUANG
Front. Environ. Sci. Eng..  2014, 8 (6): 805-819.   https://doi.org/10.1007/s11783-014-0756-8
Abstract   HTML   PDF (527KB)

China has been the forerunner of large-scale membrane bioreactor (MBR) application. Since the first large-scale MBR (≥10 000 m3·d-1) was put into operation in 2006, the engineering implementation of MBR in China has attained tremendous development. This paper outlines the commercial application of MBR since 2006 and provides a variety of engineering statistical data, covering the fields of municipal wastewater, industrial wastewater, and polluted surface water treatment. The total treatment capacity of MBRs reached 1 × 106 m3·d-1 in 2010, and has currently exceeded 4.5 × 106 m3·d-1 with ~75% of which pertaining to municipal wastewater treatment. The anaerobic/anoxic/aerobic-MBR and its derivative processes have been the most popular in the large-scale municipal application, with the process features and typical ranges of parameters also presented in this paper. For the treatment of various types of industrial wastewater, the configurations of the MBR-based processes are delineated with representative engineering cases. In view of the significance of the cost issue, statistics of capital and operating costs are also provided, including cost structure and energy composition. With continuous stimulation from the environmental stress, political propulsion, and market demand in China, the total treatment capacity is expected to reach 7.5 × 106 m3·d-1 by 2015 and a further expansion of the market is foreseeable in the next five years. However, MBR application is facing several challenges, such as the relatively high energy consumption. Judging MBR features and seeking suitable application areas should be of importance for the long-term development of this technology.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(54) WebOfScience(63)
Degradation of bisphenol A by microorganisms immobilized on polyvinyl alcohol microspheres
Xue BAI, Hanchang SHI, Zhengfang YE, Qiujin SUN, Qing WANG, Zhongyou WANG
Front Envir Sci Eng.  2013, 7 (6): 844-850.   https://doi.org/10.1007/s11783-013-0487-2
Abstract   HTML   PDF (225KB)

In this study, microorganisms (named B111) were immobilized on polyvinyl alcohol microspheres prepared by the inverse suspension crosslinked method. The biodegradation of bisphenol A (BPA) and 4-hydroxybenzaldehyde, a degradation product of BPA, by free and immobilized B111 was investigated. The BPA degradation studies were carried out at initial BPA concentrations ranging from 25 to 150 mg·L-1. The affinity constant Ks and maximum degradation rate Rmax were 98.3 mg·L-1 and 19.7 mg·mg-1VSS·d-1 for free B111, as well as 87.2 mg·L-1 and 21.1 mg·mg-1VSS·d-1 for immobilized B111, respectively. 16S rDNA gene sequence analyses confirmed that the dominant genera were Pseudomonas and Brevundimonas for BPA biodegradation in microorganisms B111.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(8) WebOfScience(7)
Fluorescence spectroscopic studies of the effect of granular activated carbon adsorption on structural properties of dissolved organic matter fractions
Shuang XUE, Qingliang ZHAO, Liangliang WEI, Xiujuan HUI, Xiping MA, Yingzi LIN
Front Envir Sci Eng.  2012, 6 (6): 784-796.   https://doi.org/10.1007/s11783-012-0436-5
Abstract   HTML   PDF (753KB)

This work investigated the effect of granular activated carbon adsorption (GACA) on fluorescence characteristics of dissolved organic matter (DOM) in secondary effluent, by means of excitation–emission matrix (EEM) spectra, the fluorescence regional integration (FRI) method, synchronous spectra, the fluorescence index defined as the ratio of fluorescence emission intensity at wavelength 450 nm to that at 500 nm at excitation (λex)=370 nm, and the wavelength that corresponds to the position of the normalized emission band at its half intensity (λ0.5). DOM in the secondary effluent from the North Wastewater Treatment Plant (Shenyang, China) was fractionated using XAD resins into 5 fractions: hydrophobic acid (HPO–A), hydrophobic neutral (HPO–N), transphilic acid (TPI–A), transphilic neutral (TPI–N) and hydrophilic fraction (HPI). Results showed that fluorescent materials in HPO–N and TPI–N were less readily removed than those in the other fractions by GACA. The relative content of fluorescent materials in HPO–A, TPI–A and HPI decreased whereas that in HPO–N and TPI–N increased as a consequence of GACA. Polycyclic aromatics in all DOM fractions were preferentially absorbed by GACA, in comparison with bulk DOM expressed as DOC. On the other hand, the adsorption of aromatic amino acids and humic acid-like fluorophores exhibiting fluorescence peaks in synchronous spectra by GACA seemed to be dependent on the acid/neutral properties of DOM fractions. All five fractions had decreased fluorescence indices as a result of GACA. GACA led to a decreased λ0.5 value for HPO–A, increased λ0.5 values for HPO–N, TPI–A and HPI, and a consistent λ0.5 value for TPI–N.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(8) WebOfScience(11)
Promotion of transition metal oxides on the NH3-SCR performance of ZrO2-CeO2 catalyst
Weiman Li, Haidi Liu, Yunfa Chen
Front. Environ. Sci. Eng..  2017, 11 (2): 6.   https://doi.org/10.1007/s11783-017-0914-x
Abstract   HTML   PDF (371KB)

Manganese and chromium oxides promote the NH3-SCR activity of Zr-Ce mixed oxide.

Cr-Zr-Ce mixed oxide exhibited>80% NOx conversion at a wide temperature window.

More acid sites and higher reducibility may responsible for the high SCR ability.

Chromium oxide and manganese oxide promoted ZrO2-CeO2 catalysts were prepared by a homogeneous precipitation method for the selective catalytic reduction of NOx with NH3. A series of characterization including X-ray diffraction (XRD), high-resolution transmission electron microscope (HR-TEM), Brunauer–Emmett–Teller (BET) surface area analysis, H2 temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS) were used to evaluate the influence of the physicochemical properties on NH3-SCR activity. Cr-Zr-Ce and Mn-Zr-Ce catalysts are much more active than ZrO2-CeO2 binary oxide for the low temperature NH3-SCR, mainly because of the high specific surface area, more surface oxygen species, improved reducibility derived from synergistic effect among different elements. Mn-Zr-Ce catalyst exhibited high tolerance to SO2 and H2O. Cr-Zr-Ce mixed oxide exhibited>80% NOx conversion at a wide temperature window of 100°C–300°C. In situ DRIFT studies showed that the addition of Cr is beneficial to the formation of Bronsted acid sites and prevents the formation of stable nitrate species because of the presence of Cr6+. The present mixed oxide can be a candidate for the low temperature abatement of NOx.

Table and Figures | Reference | Supplementary Material | Related Articles | Metrics
Cited: Crossref(3) WebOfScience(5)
Air quality improvement in Los Angeles—Perspectives for developing cities Collection
David D. Parrish,Jin Xu,Bart Croes,Min Shao
Front. Environ. Sci. Eng..  2016, 10 (5): 11.   https://doi.org/10.1007/s11783-016-0859-5
Abstract   HTML   PDF (4930KB)

Air quality improvement in Los Angeles can inform air quality policies in developing cities.

Emission control efforts, their results, costs and health benefits are briefly summarized.

Today's developing cities face new challenges including regional pollution.

Air quality issues in Beijing are briefly compared and contrasted with Los Angeles.

Opportunities for co-benefits for climate and air quality improvement are identified.

Air quality improvement in Los Angeles, California is reviewed with an emphasis on aspects that may inform air quality policy formulation in developing cities. In the mid-twentieth century the air quality in Los Angeles was degraded to an extent comparable to the worst found in developing cities today; ozone exceeded 600 ppb and annual average particulate matter <10 mm reached ~150 mg·m−3. Today's air quality is much better due to very effective emission controls; e.g., modern automobiles emit about 1% of the hydrocarbons and carbon monoxide emitted by vehicles of 50 years ago. An overview is given of the emission control efforts in Los Angeles and their impact on ambient concentrations of primary and secondary pollutants; the costs and health benefits of these controls are briefly summarized. Today's developing cities have new challenges that are discussed: the effects of regional pollution transport are much greater in countries with very high population densities; often very large current populations must be supplied with goods and services even while economic development and air quality concerns are addressed; and many of currently developing cities are located in or close to the tropics where photochemical processing of pollution is expected to be more rapid than at higher latitudes. The air quality issues of Beijing are briefly compared and contrasted with those of Los Angeles, and the opportunities for co-benefits for climate and air quality improvement are pointed out.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(10) WebOfScience(20)
Decomposition of perfluorooctanoic acid by microwave-activated persulfate: Effects of temperature, pH, and chloride ions
Yuchi LEE, Shanglien LO, Jeff KUO, Chinghong HSIEH
Front Envir Sci Eng.  2012, 6 (1): 17-25.   https://doi.org/10.1007/s11783-011-0371-x
Abstract   HTML   PDF (225KB)

Microwave-hydrothermal treatment of persistent and bioaccumulative perfluorooctanoic acid (PFOA) in water with persulfate (S2O82-) has been found effective. However, applications of this process to effectively remediate PFOA pollution require a better understanding on free-radical scavenging reactions that also take place. The objectives of this study were to investigate the effects of pH (pH= 2.5, 6.6, 8.8, and 10.5), chloride concentrations (0.01–0.15 mol·L-1), and temperature (60°C, 90°C, and 130°C) on persulfate oxidation of PFOA under microwave irradiation. Maximum PFOA degradation occurred at pH 2.5, while little or no degradation at pH 10.5. Lowering system pH resulted in an increase in PFOA degradation rate. Both high pH and chloride concentrations would result in more scavenging of sulfate free radicals and slow down PFOA degradation. When chloride concentrations were less than 0.04 mol·L-1 at 90°C and 0.06 mol·L-1 at 60°C, presence of chloride ions had insignificant impacts on PFOA degradation. However, beyond these concentration levels, PFOA degradation rates reduced significantly with an increase in chloride concentrations, especially under the higher temperature.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(34) WebOfScience(43)
Preparation of a novel anion exchange group modified hyper-crosslinked resin for the effective adsorption of both tetracycline and humic acid
Qing ZHOU, Mengqiao WANG, Aimin LI, Chendong SHUANG, Mancheng ZHANG, Xiaohan LIU, Liuyan WU
Front Envir Sci Eng.  2013, 7 (3): 412-419.   https://doi.org/10.1007/s11783-013-0483-6
Abstract   HTML   PDF (253KB)

A novel hyper-crosslinked resin (MENQ) modified with an anion exchange group was prepared using divinylbenzene (DVB) and methyl acrylate (MA) as comonomers via four steps: suspension polymerization, post-crosslinking, ammonolysis and alkylation reactions. The obtained resin had both a high specific surface area (793.34 m2·g-1) and a large exchange capacity (strong base anion exchange capacity, SEC: 0.74 mmol·g-1, weak base anion exchange capacity, WEC: 0.45 mmol·g-1). XAD-4 was selected as an adsorbent for comparison to investigate the adsorption behavior of tetracycline (TC) and humic acid (HA) onto the adsorbents. The results revealed that MENQ could effectively remove both TC and HA. The adsorption capacity of XAD-4 for TC was similar to that of MENQ, but XAD-4 exhibited poor performance for the adsorption of HA. The adsorption isotherms of TC and HA were well-fitted with the Freundlich model, which indicated the existence of heterogeneous adsorption through cation-π bonding and π–π interactions. The optimal solution condition for the adsorption of TC was at a pH of 5–6, whereas the adsorption of HA was enhanced with increasing pH of the solution.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(8) WebOfScience(12)
Transport of antibiotic resistance plasmids in porous media and the influence of surfactants
Peipei Chen, Chaoqi Chen, Xiqing Li
Front. Environ. Sci. Eng..  2018, 12 (2): 5.   https://doi.org/10.1007/s11783-017-0986-7
Abstract   HTML   PDF (1347KB)

Indigenous and engineered plasmids have similar transport behavior in porous media.

Indigenous plasmid pK5 transports similarly in quartz sand and soil.

Anionic surfactant SDS has negligible effect on plasmid transport in porous media.

Cationic surfactant CTAB affects plasmid transport at high concentrations.

Indigenous plasmids may transport over significant distances in environment.

Transport of engineered antibiotic resistance plasmids in porous media has been reported to potentially cause significant spreading of antibiotic resistance in the environment. In this work, transport of an indigenous resistance plasmid pK5 in porous media was investigated through packed column experiments. At identical ionic strengths in CaCl2 solutions, the breakthroughs of pK5 from soil columns were very close to those from quartz sand columns, indicating that transport of pK5 in quartz sand and soil was similar. A similarity in transport behavior was also found between pK5 and an engineered plasmid pBR322 that has approximately the same number of base pairs as pK5. The influence of surfactants, a major group of constituents in soil solutions, was examined using an engineered plasmid pcDNA3.1(+)/myc-His A. The impact of an anionic surfactant, sodium dodecyl sulfate (SDS), was negligible at concentrations up to 200 mg·L1. Cetyltrimethyl ammonium bromide (CTAB), a cationic surfactant, was found to significantly enhance plasmid adsorption at high concentrations. However, at environmentally relevant concentrations (<1 mg·L1), the effect of this surfactant was also minimal. The negligible impact of surfactants and the similarity between the transport of engineered and indigenous plasmids indicate that under environmentally relevant conditions, indigenous plasmids in soil also have the potential to transport over long distances and lead to the spreading of antibiotic resistance.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(3) WebOfScience(3)
Characterization of chlorine dioxide as disinfectant for the removal of low concentration microcystins
Mingsong WU, Junli HUANG, Yuling ZHANG, Shijie YOU, Shaofeng LI, Zhilin RAN, Yu TIAN
Front Envir Sci Eng.  2012, 6 (1): 75-81.   https://doi.org/10.1007/s11783-011-0331-5
Abstract   HTML   PDF (180KB)

Microcystins, which represents one kind of cancerogenic organic compounds, is abundant in eutrophication water. The effects of reaction factors on chlorine dioxide (ClO2) for removal of low-concentration Microcystin-LR, Microcystin-RR, and Microcystin-YR in water as well as the reaction mechanisms was investigated by using enzyme-linked immunosorbent assay (ELISA) kit and gas chromatography–mass spectrometry (GC-MS). The results showed that MC-LR, MC-RR, and MC-YR could be efficiently decomposed by ClO2. The degradation efficiency was shown positively correlated to the concentration of ClO2 and reaction time; while the effect of reaction temperature and pH is slight. The kinetic constants and activation energies of the reaction of MC-LR, MC-RR, and MC-YR with ClO2 are determined as 459.89, 583.15, 488.43 L·(mol·min)-1 and 64.78, 53.01, 59.15 kJ·mol-1, respectively. As indicated by high performance liquid chromatography mass spectrometer (HPLC-MS) analysis, degradation should be accomplished via destruction of Adda group by oxidation, with the formation of dihydroxy substituendums as end products. This study has provided a fundamental demonstration of ClO2 serving as oxidizing disinfectant to eliminate microcystins from raw water source.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(3) WebOfScience(3)
Effects of heavy rainfall on the composition of airborne bacterial communities
Gwang Il Jang, Chung Yeon Hwang, Byung Cheol Cho
Front. Environ. Sci. Eng..  2018, 12 (2): 12.   https://doi.org/10.1007/s11783-018-1008-0
Abstract   HTML   PDF (388KB)

Airborne bacterial community composition changed between before and after rainfall.

Actinobacteria and Firmicutes, respectively, increased and decreased after rain.

Rainfalls might have adverse effects on human and plant health.

Wet deposition scavenges particles and particle-associated bacteria from the air column, but the impact of raindrops on various surfaces on Earth causes emission of surface-associated bacteria into the air column. Thus, after rainfall, these two mechanisms are expected to cause changes in airborne bacterial community composition (BCC). In this study, aerosol samples were collected at a suburban site in Seoul, Korea before and after three heavy rainfall events in April, May, and July 2011. BCC was investigated by pyrosequencing the 16S rRNA gene in aerosol samples. Interestingly, the relative abundance of non-spore forming Actinobacteria operational taxonomic units (OTUs) was always higher in post-rain aerosol samples. In particular, the absolute and relative abundances of airborne Propionibacteriaceae always increased after rainfall, whereas those of airborne Firmicutes, including Carnobacteriaceae and Clostridiales, consistently decreased. Marine bacterial sequences, which were temporally important in aerosol samples, also decreased after rainfall events. Further, increases in pathogen-like sequences were often observed in post-rain air samples. Rainfall events seemed to affect airborne BCCs by the combined action of the two mechanisms, with potentially adverse effects on human and plant health.

Table and Figures | Reference | Supplementary Material | Related Articles | Metrics
Cited: Crossref(4) WebOfScience(6)
Long-term trends of fine particulate matter and chemical composition in the Pearl River Delta Economic Zone (PRDEZ), China
Xuemei WANG,Weihua CHEN,Duohong CHEN,Zhiyong WU,Qi Fan
Front. Environ. Sci. Eng..  2016, 10 (1): 53-62.   https://doi.org/10.1007/s11783-014-0728-z
Abstract   HTML   PDF (1478KB)

Understanding the trends in PM2.5 levels is essential for formulating clean air plans. This paper analyzes PM2.5 data from various published sources for the years 2000 to 2010 in the Pearl River Delta Economic Zone (PRDEZ). The long-term variation in PM2.5 mass concentration is analyzed. Results show that PM2.5, organic carbon (OC), elemental carbon (EC), and SO42 show a similar trend, increasing before 2005 and then decreasing slightly. The annual average PM2.5 concentration ranges from 49.1 μg·m−3 in 2000 to 64.3 μg·m−3 in 2010, with a peak of 84.1 μg·m−3 in 2004. None of these 11 years meets the new National Ambient Air Quality standard (NAAQS) for PM2.5 (35 μg·m−3). Overall average concentrations of OC, EC, and SO42 are 13.0, 6.5, and 11.8 μg·m−3, respectively. NO3 and NH4+ respectively have concentrations of 1.5 μg·m−3 and 2.9 μg·m−3 in 2000 and 6.4 μg·m−3 and 5.3 μg·m−3 in 2010, with a statistically significant average annual trend of+ 0.2 μg·m−3·yr−1 and+ 0.1 μg·m−3·yr−1. In certain geographic regions, OC and EC contribute most of the PM2.5, while in other regions secondary water-soluble ions are more important. In general, OC and SO42 are the dominant components of PM2.5, contributing 20.6% and 18.6%, respectively. These results provide, for the first time, a better understanding of the long-term PM2.5 characteristics and trends, on a species-by-species basis, in the PRDEZ. The results indicate that PM2.5 abatement needs to prioritize secondary species.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(19) WebOfScience(26)
Approaching the binding between Cu(II) and aerobic granules by a modified titration and µ-XRF
Hongwei LUO,Longfei WANG,Zhonghua TONG,Hanqing YU,Guoping SHENG
Front. Environ. Sci. Eng..  2016, 10 (2): 362-367.   https://doi.org/10.1007/s11783-015-0803-0
Abstract   HTML   PDF (815KB)

Interactions between metals and activated sludge can substantially affect the fate and transport of heavy metals in wastewater treatment plants. Therefore, it is important to develop a simple, fast and efficient method to elucidate the interaction. In this study, a modified titration method with a dynamic mode was developed to investigate the binding of Cu(II), a typical heavy metal, onto aerobic granules. The titration results indicated that pH and ionic strength both had a positive effect on the biosorption capacity of the granular sludge. The µ-XRF results demonstrated that the distribution of metals on the granular surface was heterogeneous, and Cu showed strong correlations and had the same “hot spots” positions with other metal ions (e.g., Ca, Mg, Fe etc.). Ion exchange and complexing were the main mechanisms for the biosorption of Cu(II) by aerobic granules. These results would be beneficial for better understanding of Cu(II) migration and its fate in wastewater treatment plants.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(5) WebOfScience(5)
NO oxidation over Co-La catalysts and NOx reduction in compact SCR
Tiejun Zhang, Jian Li, Hong He, Qianqian Song, Quanming Liang
Front. Environ. Sci. Eng..  2017, 11 (2): 4.   https://doi.org/10.1007/s11783-017-0906-x
Abstract   HTML   PDF (1049KB)

The Co-La catalyst (pH= 1) exhibited maximum NO conversion of 43% at 180°C.

Acid modified catalyst enhanced the resistance to SO2.

The formed sulfates may block the pore structure of the catalyst.

The NO conversion of compact SCR was 91% at 180°C at the highest space velocity.

A series of Co-La catalysts were prepared using the wet impregnation method and the synthesis of catalysts were modified by controlling pH with the addition of ammonium hydroxide or oxalic solution. All the catalysts were systematically investigated for NO oxidation and SO2 resistance in a fixed bed reactor and were characterized by Brunanuer–Emmett–Teller (BET) method, Fourier Transform infrared spectroscopy (FTIR), X–ray diffraction (XRD), Thermogravimetric (TG) and Ion Chromatography (IC). Among the catalysts, the one synthesized at pH= 1 exhibited the maximum NO conversion of 43% at 180°C. The activity of the catalyst was significantly suppressed by the existence of SO2 (300 ppm) at 220°C. Deactivation may have been associated with the generation of cobalt sulfate, and the SO2 adsorption quantity of the catalyst might also have effected sulfur resistance. In the case of the compact selective catalytic reduction (SCR), the activity increased from 74% to 91% at the highest gas hourly space velocity (GHSV) of 300000 h1 when the NO catalyst maintained the highest activity, in excess of 50% more than that of the standard SCR.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(1) WebOfScience(1)
A review of atmospheric mercury emissions, pollution and control in China
Shuxiao WANG,Lei ZHANG,Long WANG,Qingru WU,Fengyang WANG,Jiming HAO
Front.Environ.Sci.Eng..  2014, 8 (5): 631-649.   https://doi.org/10.1007/s11783-014-0673-x
Abstract   HTML   PDF (583KB)

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.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(60) WebOfScience(70)
Research progress on hydrothermal dissolution and hydrolysis of lignocellulose and lignocellulosic waste
Yan ZHAO, Wenjing LU, Jiajun CHEN, Xiangfeng ZHANG, Hongtao WANG
Front Envir Sci Eng.  2014, 8 (2): 151-161.   https://doi.org/10.1007/s11783-013-0607-z
Abstract   HTML   PDF (318KB)

Ethanol production from lignocellulosic waste has attracted considerable attention because of its feasibility and the generation of valuable products. Previous studies have shown that pretreatment and hydrolysis are key processes for lignocellulose conversion. Hydrothermal process is a promising technique because of its efficiency to break down the lignocellulosic structures and produce fermentable hexoses. Most studies in this field have therefore focused on understanding these processes or optimizing the parameters, but commonly reported low yields of fermentable hexoses. The inability to produce high yields of fermentable hexoses is mainly attributed to inadequate information on the conversion mechanisms of lignocellulose, particularly the reaction rules of dissolution, which is a limiting step in the entire conversion process. This paper critically reviewed the progress done in the research and development of the hydrothermal dissolution and hydrolysis of lignocellulose. Principles, processes, and related studies on separate dissolution and asynchronous hydrolysis of lignin, hemicellulose, and cellulose are presented. Potential research prospects are also suggested.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(11) WebOfScience(15)
Key features of new particle formation events at background sites in China and their influence on cloud condensation nuclei Collection
Xiaojing SHEN,Junying SUN,Xiaoye ZHANG,Yangmei ZHANG,Lu ZHANG,Ruxia FAN
Front. Environ. Sci. Eng..  2016, 10 (5): 5.   https://doi.org/10.1007/s11783-016-0833-2
Abstract   HTML   PDF (955KB)

New particle formation (NPF) event at multi rural sites in China

Identifying the characteristics of NPF event

Comparing NPF event between clean and polluted conditions

Quantifying contribution to the cloud condensation nuclei

Implication of climate and air quality

Long-term continuous measurements of particle number size distributions with mobility diameter sizes ranging from 3 to 800 nm were performed to study new particle formation (NPF) events at Shangdianzi (SDZ), Mt. Tai (TS), and Lin’an (LAN) stations representing the background atmospheric conditions in the North China Plain (NCP), Central East China (CEC), and Yangtze River Delta (YRD) regions, respectively. The mean formation rate of 3-nm particles was 6.3, 3.7, and 5.8 cm−3·s−1, and the mean particle growth rate was 3.6, 6.0, and 6.2 nm·h−1 at SDZ, TS, and LAN, respectively. The NPF event characteristics at the three sites indicate that there may be a stronger source of low volatile vapors and higher condensational sink of pre-existing particles in the YRD region. The formation rate of NPF events at these sites, as well as the condensation sink, is approximately 10 times higher than some results reported at rural/urban sites in western countries. However, the growth rates appear to be 1–2 times higher. Approximately 12%–17% of all NPF events with nucleated particles grow to a climate-relevant size (>50 nm). These kinds of NPF events were normally observed with higher growth rate than the other NPF cases. Generally, the cloud condensation nuclei (CCN) number concentration can be enhanced by approximately a factor of 2–6 on these event days. The mean value of the enhancement factor is lowest at LAN (2–3) and highest at SDZ (~4). NPF events have also been found to have greater impact on CCN production in China at the regional scale than in the other background sites worldwide.

Table and Figures | Reference | Supplementary Material | Related Articles | Metrics
Cited: Crossref(12) WebOfScience(14)
Addressing the environmental risk of persistent organic pollutants in China
Bin WANG, Jun HUANG, Shubo DENG, Xiaoling YANG, Gang YU
Front Envir Sci Eng.  2012, 6 (1): 2-16.   https://doi.org/10.1007/s11783-011-0370-y
Abstract   HTML   PDF (682KB)

The Stockholm Convention on persistent organic pollutants (POPs) was adopted in 2001. This year is the 10th anniversary of the adoption of the Convention. Until now, 22 chemicals or chemical categories have been listed as POPs in the Stockholm Convention. The POPs Research Center was established in Tsinghua University in the same year when the Convention was adopted. In the last ten years, much work has been done by Chinese researchers to understand the environmental risk of POPs in China. This article aims to review the recent research progress of our POPs Research Center and some other Chinese researchers’ studies in addressing the environmental risk of POPs, including the priority screening and inventory study of POPs, monitoring and modeling of POPs pollution and exposure, and environmental risk assessment and modeling of POPs. Although great advances in addressing the environmental risk of POPs have been made in recent years, we are still facing quite a few problems, such as data scarcity and uncertainty in environmental risk assessment of POPs. The study on the effect of POPs mixtures is in its infancy and currently POPs are usually assessed from legal perspective by risk assessment of single chemicals. These problems should be well addressed by further efforts. Further studies should also be taken in future to study environment risk of POPs by considering aspects of coupled dynamics between climate processes and POPs. Such sound scientific, risk-based information can support decision-making aiming to effectively minimize the risk level of POPs.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(19) WebOfScience(21)
Activated carbons and amine-modified materials for carbon dioxide capture –– a review
Zhenhe CHEN, Shubo DENG, Haoran WEI, Bin WANG, Jun HUANG, Gang YU
Front Envir Sci Eng.  2013, 7 (3): 326-340.   https://doi.org/10.1007/s11783-013-0510-7
Abstract   HTML   PDF (293KB)

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.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(68) WebOfScience(85)
Long-term observation of air pollution-weather/climate interactions at the SORPES station: a review and outlook Collection
Aijun Ding,Wei Nie,Xin Huang,Xuguang Chi,Jianning Sun,Veli-Matti Kerminen,Zheng Xu,Weidong Guo,Tuukka Petäjä,Xiuqun Yang,Markku Kulmala,Congbin Fu
Front. Environ. Sci. Eng..  2016, 10 (5): 15.   https://doi.org/10.1007/s11783-016-0877-3
Abstract   HTML   PDF (964KB)

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.

Table and Figures | Reference | Supplementary Material | Related Articles | Metrics
Cited: Crossref(19) WebOfScience(29)
Chemical poison and regeneration of SCR catalysts for NOx removal from stationary sources
Junhua LI,Yue PENG,Huazhen CHANG,Xiang LI,John C. CRITTENDEN,Jiming HAO
Front. Environ. Sci. Eng..  2016, 10 (3): 413-427.   https://doi.org/10.1007/s11783-016-0832-3
Abstract   HTML   PDF (951KB)

Selective catalytic reduction (SCR) of NOx with NH3 is an effective technique to remove NOx from stationary sources, such as coal-fired power plant and industrial boilers. Some of elements in the fly ash deactivate the catalyst due to strong chemisorptions on the active sites. The poisons may act by simply blocking active sites or alter the adsorption behaviors of reactants and products by an electronic interaction. This review is mainly focused on the chemical poisoning on V2O5-based catalysts, environmental-benign catalysts and low temperature catalysts. Several common poisons including alkali/alkaline earth metals, SO2 and heavy metals etc. are referred and their poisoning mechanisms on catalysts are discussed. The regeneration methods of poisoned catalysts and the development of poison-resistance catalysts are also compared and analyzed. Finally, future research directions in developing poisoning resistance catalysts and facile efficient regeneration methods for SCR catalysts are proposed.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(35) WebOfScience(46)
Water, energy and food interactions–Challenges and opportunities
Gustaf OLSSON
Front Envir Sci Eng.  2013, 7 (5): 787-793.   https://doi.org/10.1007/s11783-013-0526-z
Abstract   HTML   PDF (160KB)

Water and energy are inextricably linked, and as a consequence both have to be addressed together. This is called the water-energy nexus. When access to either is limited, it becomes obvious that it is necessary to consider their interdependence. Population growth, climate change, urbanization, increasing living standards and food consumption will require an integrated approach where food, water and energy security are considered together. In this paper we examine water, energy and food security and their couplings. The nexus also creates conflicts between water use, energy extraction and generation as well as food production. Some of these conflicts are illustrated. It is argued that there is an urgent need for integrated planning and operation. Not only will better technology be needed, but also better integration of policies, organizations and political decisions.

Table and Figures | Reference | Related Articles | Metrics
Cited: Crossref(25) WebOfScience(35)