Antibiotics released into the environment through anthropogenic activities exert selective pressure,driving bacteria towards increasing antimicrobial resistance.The prevalence of antibiotics and the ecological risks p...Antibiotics released into the environment through anthropogenic activities exert selective pressure,driving bacteria towards increasing antimicrobial resistance.The prevalence of antibiotics and the ecological risks posed in the riverine estuarine of Larut River and Sangga Besar River,which included wastewater effl uents from hospital,zoo,and poultry slaughterhouse sources were investigated.Solid phase extraction(SPE)followed by high-performance liquid chromatography tandem mass chromatography(HPLC-MS/MS)were used to extract and quantify the antibiotic residues from 22 antibiotics belonging to six major antibiotic classes(sulfonamide,macrolide,fl uoroquinolone,phenicol,trimethoprim,and tetracycline).Sixteen antibiotic residues were detected with concentrations ranging from limit of detection(LOD)to 1262.3 ng/L.Fluoroquinolones and macrolides were the most frequently detected compounds.Erythromycin,clarithromycin,and ofl oxacin detected in hospital and zoo effl uents posed a high risk to algae while tetracycline had low to medium ecological risks toward all the relevant organisms from aquatic environments(algae,invertebrate Daphnia magna,and fi sh).展开更多
Thirty-six polyurethane foam disk passive air samplers （PUF-PAS） were deployed over a year during January to December, 2009 at three locations, i.e., Imphal （urban site）, Thoubal （rural site） and Waithou （alpin...Thirty-six polyurethane foam disk passive air samplers （PUF-PAS） were deployed over a year during January to December, 2009 at three locations, i.e., Imphal （urban site）, Thoubal （rural site） and Waithou （alpine site） of Manipur, to assess the seasonal local atmospheric emission of selected organochlorine pesticides （OCPs）. The average concentration of HCHs monitored at mountain site during hot season （Mar, Apr, and May） and rainy seasons （Jun, Jul, Aug, and Sep） were 403 and 349 pg/m3, respectively. DDTs had a high concentration with 384 pg/m3 at rural site and 379 pg/m3 at urban site during hot seasons. Endosulfans and chlordane were found high in concentration during hot seasons （260 pg/m3） and low during retreating monsoon seasons （44 pg/m3） at rural site. Most of the OCPs concentrations were high during cultivation period. The OCP concentrations of rainy season were highly correlated （p 〈 0.01） with OCPs of hot seasons. Further, positive correlation （p 〈 0.05） was also obtained between cold seasons and retreating monsoon. Principal component analysis showed a significant correlation among the four seasons and distribution pattern of OCPs in air. Back trajectory analysis by using HYPSLIT model showed a long range air transport of OCPs to the present study area. Present OCP levels at Manipur is an outcome of both local emission and also movement of air mass by long range atmospheric transport.展开更多
Organophosphate flame retardants(OPFRs),as a replacement for polybrominated diphenyl ethers(PBDEs),are of increasing concern due to their high production over the years.Soil is the major environmental reservoir and in...Organophosphate flame retardants(OPFRs),as a replacement for polybrominated diphenyl ethers(PBDEs),are of increasing concern due to their high production over the years.Soil is the major environmental reservoir and interchange for OPFRs.OPFRs in soil could be transferred to the food chain,and pose potential ecological and human health risks.This review focused on the environmental fate and effects of typical OPFRs in the soil-plant system.We concluded that the sorption and transformation behaviors of OPFRs due to their crucial impact on bioavailability.The root uptake and translocation of OPFRs by plants were summarized with analyses of their potential affecting factors.The in planta transformation and potential ecological effects of OPFRs were also briefly discussed.Finally,we highlighted several research gaps and provided suggestions for future research,including the development of simulative/computative methods to evaluate the bioavailability of OPFRs,the effects of root exudates and rhizosphere microorganisms on the bioavailability and plant uptake of OPFRs,and the development of green and sustainable technologies for in situ remediation of OPFRs-contaminated soil.展开更多
Environmental contamination due to uncontrolled e-waste recycling activities is drawing increasing attention in the world. Extraction of these metals with biodegradable chelant [S,S]-ethylenediaminedisuccinic acid （E...Environmental contamination due to uncontrolled e-waste recycling activities is drawing increasing attention in the world. Extraction of these metals with biodegradable chelant [S,S]-ethylenediaminedisuccinic acid （EDDS） and the factors influencing extraction efficacy were investigated in the present study. Results showed that the addition of EDDS at low pH （5.5） produced higher metal extraction than that at high pH （8.0） solution. Metal speciation analysis indicated that Cu was completely complexed with EDDS at different pH conditions with various amounts of EDDS applied. For Pb and Zn, at low EDDS dose of 0.304 mol/kg soil, they were present as Pb- and Zn-EDDS. However, at high EDDS dose of 1.26 mol/kg soil, most of Pb was bound with dissolved organic matter. Ca and A1 were found to be strong competitors for trace metals to EDDS at low application dose and low pH condition.展开更多
Previous studies on environmental antibiotics resistance genes（ARGs） have focused on the pollution sources such as wastewater treatment plants, aquaculture and livestock farms,etc. Few of them had addressed this iss...Previous studies on environmental antibiotics resistance genes（ARGs） have focused on the pollution sources such as wastewater treatment plants, aquaculture and livestock farms,etc. Few of them had addressed this issue in a regional scale such as river catchment. Hence,the occurrence and abundances of 23 ARGs were investigated in surface water samples collected from 38 sites which located from the river source to estuary of the Beijiang River.Among them, 11 ARGs were frequently detected in this region and 5 ARGs（sul Ⅰ, sul Ⅱ, tet B,tet C, and tet W） were selected for their distribution pattern analysis. The abundances of the selected ARGs were higher in the upstream（8.70 × 10^6 copies/ng DNA） and downstream areas（3.17 × 10^6 copies/ng DNA） than those in the midstream areas（1.23 × 10^6 copies/ng DNA）, which was positively correlated to the population density and number of pollution sources. Pollution sources of ARGs along the Beijiang River not only had a great impact on the abundances and diversity, but also on the distribution of specific ARGs in the water samples. Both sul Ⅰ and sul Ⅱ were likely originated from aquaculture farms and animal farms,tet W gene was possibly associated with the mining/metal melting industry and the electric waste disposal and tet C gene was commonly found in the area with multiple pollution sources.However, the abundance of tet B was not particularly related to anthropogenic impacts. These findings highlight the influence of pollution sources and density of population on the distribution and dissemination of ARGs at a regional scale.展开更多
In January 2013, a long-lasting severe haze episode occurred in Northern and Central China; at its maximum, it covered a land area of approximately 1.4 million km2. In Wuhan, the largest city in Central China, this ev...In January 2013, a long-lasting severe haze episode occurred in Northern and Central China; at its maximum, it covered a land area of approximately 1.4 million km2. In Wuhan, the largest city in Central China, this event was the most severe haze episode in the 21st century. Aerosol samples of submicron particles （PMI.o） were collected during the long-lasting haze episode at an urban site and a suburban site in Wuhan to investigate the ion characteristics of PMi.0 in this area. The mass concentrations of PM1.0 and its water-soluble inorganic ions （WSIIs） were almost at the same levels at two sites, which indicates that PM1.0 pollution occurs on a regional scale in Wuhao. WSIIs （Na^＋, NH4^＋, K^＋, Mg^2＋, Ca^2＋, Cl^-, NO3 and SO2-） were the dominant chemical species and constituted up to 48.4% and 47.4% of PM1.0 at WD and TH, respectively. The concentrations of PM1.0 and WSIIs on haze days were approximately two times higher than on normal days. The ion balance calculations indicate that the particles were more acidic on haze days than on normal days. The results of the back trajectory analysis imply that the high concentrations of PM1.0 and its water-soluble inorganic ions may be caused by stagnant weather conditions in Wuhan.展开更多
Trace metal contamination in soils is a threat with an uncertain limit to maintain planet safety,and the issue of trace metal contamination in mountain soils is still of low concerned.In this study,we assessed the con...Trace metal contamination in soils is a threat with an uncertain limit to maintain planet safety,and the issue of trace metal contamination in mountain soils is still of low concerned.In this study,we assessed the contamination of six trace metals(Cd,Cr,Cu,Ni,Pb,and Zn)in mountain soils across China and deciphered the potential drivers of their spatial distribution.The results showed that concentrations of Cd and Pb decreased significantly with soil depth,and their concentrations were markedly higher in northwest,south,and southwest China than elsewhere.Among the metals,Cd was the priority for control with moderate to heavy contamination,followed by Pb,whereas the other metals did not show evident contamination.The altitudinal pattern and isotopic tracing revealed that the significant enrichment and marked contamination of Cd and Pb in surface soils were primarily attributed to deposition through long-range transboundary atmospheric transport and condensation.Ore mining,nonferrous smelting,and coal and fuel combustion were identified as primary anthropogenic sources of the Cd and Pb.Soil organic matter content,pH,and soil forming processes directly determined the accumulation of trace metals in the soils,and orographic effects,including local climate,vegetation composition,and canopy filtering,regulated the spatial distribution of the metals.This study highlights the significance of soil Cd contamination in mountains,which are considered of low concern,and suggests that long-term monitoring of trace metal contamination is necessary to improve biogeochemical models that evaluate the responses of the mountain critical zone to future human-and climate-induced environmental changes.展开更多
Air pollution and climate change are two important threats facing in our planet and are tightly linked to carbonaceous components in the atmosphere.A better understanding of the emission sources and environmental fate...Air pollution and climate change are two important threats facing in our planet and are tightly linked to carbonaceous components in the atmosphere.A better understanding of the emission sources and environmental fate/sink of carbonaceous components is critical for improving our knowledge of the global carbon cycle and mitigating the negative environmental impacts of air pollution and climate change on human well-being.Radiocarbon(^(14)C),which is decayed completely in fossil fuel(e.g.coal and petroleum),is an ideal tool for quantifying the carbon flow in various carbon reservoirs.This study reviews the current knowledge of 14C in organic carbon(OC),elemental carbon(EC),individual organic compounds,methane(CH_(4)),carbon dioxide(CO_(2)),annual plants,and tree rings.The impacts of fossil and non-fossil sources on the atmosphere can be quantified by measuring^(14)C.We also report on the influence of nuclear power plants and sea-air gas exchange on the abundance of^(14)C in the atmosphere.The increasing fossil fuel emissions indicated by the depletion of^(14)CO_(2)under IPCC RCP scenarios,support the urgent need to devise ambitious strategies of reducing carbonaceous components to achieve sustainable development on Earth.This review summarizes the challenges and perspectives of 14C studies of the atmosphere.展开更多
Most of the monitoring data on the occurrence of antibiotics in sewage treatment plants(STPs)have been reported from Europe,North America and some countries in Northeast Asia,while very limited data can be found in So...Most of the monitoring data on the occurrence of antibiotics in sewage treatment plants(STPs)have been reported from Europe,North America and some countries in Northeast Asia,while very limited data can be found in Southeast Asian countries.As a pioneering research in Sri Lanka,we collected 24 h composite wastewater samples at the influent and effluent of two municipal STPs for consecutive 7 days to investigate occurrence,consumption and removal efficiency of seventeen antibiotics.The STP was located in Colombo and Hikkaduwa,respectively,representing two kinds of communities(i.e.local and tourists)in Sri Lanka.The targeted antibiotics were extracted by solid-phase extraction method and detected on an Agilent HPLCMSMS(1290/6470QQQ).Results illustrated that the majority of the antibiotics can be always detected from both STPs,except for chlorotetracycine(CTC),doxycycline(DOX)and florfenicol(FF).Fluoroquinolones(FQs)were detected at highest concentrations with ciprofloxacin(CIP)being the dominant compound.Concentrations of CIP in the influent samples were in the range of 433 e6010 ng/L.The consumption of antibiotics was estimated on the basis of influent mass load and catchment population data.We found difference in consumption patterns between the two served areas.Compared to local people in Colombo,tourists in Hikkaduwa appeared to take more antibiotics during the study period with the estimated daily dose of 0.25 g per 1000 persons.Moreover,macrolides accounted for a larger portion than FQs in Hikkaduwa,with azithromycin(AZM)being the most prevalent antibacterial agent.After comparison with an official report by Medical Supplies Division of Sri Lanka,we conjected that AZM was not commonly used among local people and it was mainly introduced by foreign arrivals.As for the removal efficiency,the activated sludge system of Colombo exhibited better elimination and more stable performance than the constructed wetland process of Hikkaduwa.展开更多
Substantial efforts are currently underway around the world to develop environmentally friendly transportation,of which the development of electric vehicles plays a key role.Statorpermanent magnet(PM)machines have att...Substantial efforts are currently underway around the world to develop environmentally friendly transportation,of which the development of electric vehicles plays a key role.Statorpermanent magnet(PM)machines have attracted wide attention due to the robust rotor structure and comparable performance in terms of normal permanent magnet synchronous machines(PMSM)having magnets in the roto.In particular,the flux-switching machines feature a particular magnetic circuit configuration that favors Dy-free magnets in terms of demagnetization risk,and as a result,the cost of the motor can be reduced considerably.With focus on applications in electric vehicles(EVs)and hybrid electric vehicles(HEVs),this paper reviews the latest developments of PM flux switching machines,with particular emphasis on the novel machine topologies and control strategies.展开更多
基金Supported by the Ministry of Higher Education of Malaysia(Nos.IOES-2014D,FP048-2013A,SF022-2013)the University Malaya(Nos.RU009D-2015,PG309-2016A)。
文摘Antibiotics released into the environment through anthropogenic activities exert selective pressure,driving bacteria towards increasing antimicrobial resistance.The prevalence of antibiotics and the ecological risks posed in the riverine estuarine of Larut River and Sangga Besar River,which included wastewater effl uents from hospital,zoo,and poultry slaughterhouse sources were investigated.Solid phase extraction(SPE)followed by high-performance liquid chromatography tandem mass chromatography(HPLC-MS/MS)were used to extract and quantify the antibiotic residues from 22 antibiotics belonging to six major antibiotic classes(sulfonamide,macrolide,fl uoroquinolone,phenicol,trimethoprim,and tetracycline).Sixteen antibiotic residues were detected with concentrations ranging from limit of detection(LOD)to 1262.3 ng/L.Fluoroquinolones and macrolides were the most frequently detected compounds.Erythromycin,clarithromycin,and ofl oxacin detected in hospital and zoo effl uents posed a high risk to algae while tetracycline had low to medium ecological risks toward all the relevant organisms from aquatic environments(algae,invertebrate Daphnia magna,and fi sh).
基金supported by the Government of China and Human Resource Development Ministry, Government of India for financial assistance in the form of Chinese Government fellowship (CSC No. 2008356005)
文摘Thirty-six polyurethane foam disk passive air samplers （PUF-PAS） were deployed over a year during January to December, 2009 at three locations, i.e., Imphal （urban site）, Thoubal （rural site） and Waithou （alpine site） of Manipur, to assess the seasonal local atmospheric emission of selected organochlorine pesticides （OCPs）. The average concentration of HCHs monitored at mountain site during hot season （Mar, Apr, and May） and rainy seasons （Jun, Jul, Aug, and Sep） were 403 and 349 pg/m3, respectively. DDTs had a high concentration with 384 pg/m3 at rural site and 379 pg/m3 at urban site during hot seasons. Endosulfans and chlordane were found high in concentration during hot seasons （260 pg/m3） and low during retreating monsoon seasons （44 pg/m3） at rural site. Most of the OCPs concentrations were high during cultivation period. The OCP concentrations of rainy season were highly correlated （p 〈 0.01） with OCPs of hot seasons. Further, positive correlation （p 〈 0.05） was also obtained between cold seasons and retreating monsoon. Principal component analysis showed a significant correlation among the four seasons and distribution pattern of OCPs in air. Back trajectory analysis by using HYPSLIT model showed a long range air transport of OCPs to the present study area. Present OCP levels at Manipur is an outcome of both local emission and also movement of air mass by long range atmospheric transport.
基金the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2017BT01Z134)the National Natural Science Foundation of China(32061133003 and 41603086)+1 种基金the Guangdong Foundation for Program of Science and Technology Research(2019B121205006)Ten Thousand Talent Program of the Organization Department of the Central Committee of the CPC。
文摘Organophosphate flame retardants(OPFRs),as a replacement for polybrominated diphenyl ethers(PBDEs),are of increasing concern due to their high production over the years.Soil is the major environmental reservoir and interchange for OPFRs.OPFRs in soil could be transferred to the food chain,and pose potential ecological and human health risks.This review focused on the environmental fate and effects of typical OPFRs in the soil-plant system.We concluded that the sorption and transformation behaviors of OPFRs due to their crucial impact on bioavailability.The root uptake and translocation of OPFRs by plants were summarized with analyses of their potential affecting factors.The in planta transformation and potential ecological effects of OPFRs were also briefly discussed.Finally,we highlighted several research gaps and provided suggestions for future research,including the development of simulative/computative methods to evaluate the bioavailability of OPFRs,the effects of root exudates and rhizosphere microorganisms on the bioavailability and plant uptake of OPFRs,and the development of green and sustainable technologies for in situ remediation of OPFRs-contaminated soil.
基金supported by the Research Grants Council of the Hong Kong SAR Government (No.PolyU5212/08E)the Natural Science Foundation of Jiangsu Province (No.BK2010064)+1 种基金the Social Development Foundation of Jiangsu Province (No.BE2011781)Joint Funds of the National Natural Science Foundation of China and the Natural Science Foundation of Guangdong Province, China (No.NSFC-GDNSF, U1133004)
文摘Environmental contamination due to uncontrolled e-waste recycling activities is drawing increasing attention in the world. Extraction of these metals with biodegradable chelant [S,S]-ethylenediaminedisuccinic acid （EDDS） and the factors influencing extraction efficacy were investigated in the present study. Results showed that the addition of EDDS at low pH （5.5） produced higher metal extraction than that at high pH （8.0） solution. Metal speciation analysis indicated that Cu was completely complexed with EDDS at different pH conditions with various amounts of EDDS applied. For Pb and Zn, at low EDDS dose of 0.304 mol/kg soil, they were present as Pb- and Zn-EDDS. However, at high EDDS dose of 1.26 mol/kg soil, most of Pb was bound with dissolved organic matter. Ca and A1 were found to be strong competitors for trace metals to EDDS at low application dose and low pH condition.
基金supported by the National Natural Science Foundation of China(Nos.21177162 and 51579253)the Commodity Inspection and Quarantine in Nanhai,Foshan,for their assistance in the determinations of antibiotics in this project
文摘Previous studies on environmental antibiotics resistance genes（ARGs） have focused on the pollution sources such as wastewater treatment plants, aquaculture and livestock farms,etc. Few of them had addressed this issue in a regional scale such as river catchment. Hence,the occurrence and abundances of 23 ARGs were investigated in surface water samples collected from 38 sites which located from the river source to estuary of the Beijiang River.Among them, 11 ARGs were frequently detected in this region and 5 ARGs（sul Ⅰ, sul Ⅱ, tet B,tet C, and tet W） were selected for their distribution pattern analysis. The abundances of the selected ARGs were higher in the upstream（8.70 × 10^6 copies/ng DNA） and downstream areas（3.17 × 10^6 copies/ng DNA） than those in the midstream areas（1.23 × 10^6 copies/ng DNA）, which was positively correlated to the population density and number of pollution sources. Pollution sources of ARGs along the Beijiang River not only had a great impact on the abundances and diversity, but also on the distribution of specific ARGs in the water samples. Both sul Ⅰ and sul Ⅱ were likely originated from aquaculture farms and animal farms,tet W gene was possibly associated with the mining/metal melting industry and the electric waste disposal and tet C gene was commonly found in the area with multiple pollution sources.However, the abundance of tet B was not particularly related to anthropogenic impacts. These findings highlight the influence of pollution sources and density of population on the distribution and dissemination of ARGs at a regional scale.
基金supported by the Natural Science Foundation of China(No.41103061)the Doctoral Fund Project of the Ministry of Education of China(No.20110141120015)the National Basic Research Programme(973)of China(No.2011CB707106)
文摘In January 2013, a long-lasting severe haze episode occurred in Northern and Central China; at its maximum, it covered a land area of approximately 1.4 million km2. In Wuhan, the largest city in Central China, this event was the most severe haze episode in the 21st century. Aerosol samples of submicron particles （PMI.o） were collected during the long-lasting haze episode at an urban site and a suburban site in Wuhan to investigate the ion characteristics of PMi.0 in this area. The mass concentrations of PM1.0 and its water-soluble inorganic ions （WSIIs） were almost at the same levels at two sites, which indicates that PM1.0 pollution occurs on a regional scale in Wuhao. WSIIs （Na^＋, NH4^＋, K^＋, Mg^2＋, Ca^2＋, Cl^-, NO3 and SO2-） were the dominant chemical species and constituted up to 48.4% and 47.4% of PM1.0 at WD and TH, respectively. The concentrations of PM1.0 and WSIIs on haze days were approximately two times higher than on normal days. The ion balance calculations indicate that the particles were more acidic on haze days than on normal days. The results of the back trajectory analysis imply that the high concentrations of PM1.0 and its water-soluble inorganic ions may be caused by stagnant weather conditions in Wuhan.
基金Youth Innovation Promotion Association of the Chinese Academy of Sciences(2017424)CAS“Light of West China”ProgramSpecial Talent Project of Sichuan Province.
文摘Trace metal contamination in soils is a threat with an uncertain limit to maintain planet safety,and the issue of trace metal contamination in mountain soils is still of low concerned.In this study,we assessed the contamination of six trace metals(Cd,Cr,Cu,Ni,Pb,and Zn)in mountain soils across China and deciphered the potential drivers of their spatial distribution.The results showed that concentrations of Cd and Pb decreased significantly with soil depth,and their concentrations were markedly higher in northwest,south,and southwest China than elsewhere.Among the metals,Cd was the priority for control with moderate to heavy contamination,followed by Pb,whereas the other metals did not show evident contamination.The altitudinal pattern and isotopic tracing revealed that the significant enrichment and marked contamination of Cd and Pb in surface soils were primarily attributed to deposition through long-range transboundary atmospheric transport and condensation.Ore mining,nonferrous smelting,and coal and fuel combustion were identified as primary anthropogenic sources of the Cd and Pb.Soil organic matter content,pH,and soil forming processes directly determined the accumulation of trace metals in the soils,and orographic effects,including local climate,vegetation composition,and canopy filtering,regulated the spatial distribution of the metals.This study highlights the significance of soil Cd contamination in mountains,which are considered of low concern,and suggests that long-term monitoring of trace metal contamination is necessary to improve biogeochemical models that evaluate the responses of the mountain critical zone to future human-and climate-induced environmental changes.
基金This research was supported by the National Natural Science Foundation of China(Nos.42030715,41877349)Guangdong Foundation for Program of Science and Technology Research(Nos.2017BT01Z134,2019B121205006)National Key R&D Program of China(2017YFC0212000).
文摘Air pollution and climate change are two important threats facing in our planet and are tightly linked to carbonaceous components in the atmosphere.A better understanding of the emission sources and environmental fate/sink of carbonaceous components is critical for improving our knowledge of the global carbon cycle and mitigating the negative environmental impacts of air pollution and climate change on human well-being.Radiocarbon(^(14)C),which is decayed completely in fossil fuel(e.g.coal and petroleum),is an ideal tool for quantifying the carbon flow in various carbon reservoirs.This study reviews the current knowledge of 14C in organic carbon(OC),elemental carbon(EC),individual organic compounds,methane(CH_(4)),carbon dioxide(CO_(2)),annual plants,and tree rings.The impacts of fossil and non-fossil sources on the atmosphere can be quantified by measuring^(14)C.We also report on the influence of nuclear power plants and sea-air gas exchange on the abundance of^(14)C in the atmosphere.The increasing fossil fuel emissions indicated by the depletion of^(14)CO_(2)under IPCC RCP scenarios,support the urgent need to devise ambitious strategies of reducing carbonaceous components to achieve sustainable development on Earth.This review summarizes the challenges and perspectives of 14C studies of the atmosphere.
基金This work was funded by the International Partnership Program of the Chinese Academy of Sciences,(Grant No.132744KYSB20170002)UCAS scholarship for international students.The authors want to acknowledge the generous support from the National Water Supply and Drainage Board(Sewerage division),Sri Lanka and to Mr.S.M.Samaraweera for the assistance in wastewater sampling.
文摘Most of the monitoring data on the occurrence of antibiotics in sewage treatment plants(STPs)have been reported from Europe,North America and some countries in Northeast Asia,while very limited data can be found in Southeast Asian countries.As a pioneering research in Sri Lanka,we collected 24 h composite wastewater samples at the influent and effluent of two municipal STPs for consecutive 7 days to investigate occurrence,consumption and removal efficiency of seventeen antibiotics.The STP was located in Colombo and Hikkaduwa,respectively,representing two kinds of communities(i.e.local and tourists)in Sri Lanka.The targeted antibiotics were extracted by solid-phase extraction method and detected on an Agilent HPLCMSMS(1290/6470QQQ).Results illustrated that the majority of the antibiotics can be always detected from both STPs,except for chlorotetracycine(CTC),doxycycline(DOX)and florfenicol(FF).Fluoroquinolones(FQs)were detected at highest concentrations with ciprofloxacin(CIP)being the dominant compound.Concentrations of CIP in the influent samples were in the range of 433 e6010 ng/L.The consumption of antibiotics was estimated on the basis of influent mass load and catchment population data.We found difference in consumption patterns between the two served areas.Compared to local people in Colombo,tourists in Hikkaduwa appeared to take more antibiotics during the study period with the estimated daily dose of 0.25 g per 1000 persons.Moreover,macrolides accounted for a larger portion than FQs in Hikkaduwa,with azithromycin(AZM)being the most prevalent antibacterial agent.After comparison with an official report by Medical Supplies Division of Sri Lanka,we conjected that AZM was not commonly used among local people and it was mainly introduced by foreign arrivals.As for the removal efficiency,the activated sludge system of Colombo exhibited better elimination and more stable performance than the constructed wetland process of Hikkaduwa.
基金part by 973 Program of China(2013CB035603)NSFC(51137001,51322705).
文摘Substantial efforts are currently underway around the world to develop environmentally friendly transportation,of which the development of electric vehicles plays a key role.Statorpermanent magnet(PM)machines have attracted wide attention due to the robust rotor structure and comparable performance in terms of normal permanent magnet synchronous machines(PMSM)having magnets in the roto.In particular,the flux-switching machines feature a particular magnetic circuit configuration that favors Dy-free magnets in terms of demagnetization risk,and as a result,the cost of the motor can be reduced considerably.With focus on applications in electric vehicles(EVs)and hybrid electric vehicles(HEVs),this paper reviews the latest developments of PM flux switching machines,with particular emphasis on the novel machine topologies and control strategies.
