In this study,the effects of low-dose sodium hypochlorite disinfection on water quality and biofilm growth in drinking water distribution systems(DWDS)after ultrafiltration pretreatment was investigated.The influence ...In this study,the effects of low-dose sodium hypochlorite disinfection on water quality and biofilm growth in drinking water distribution systems(DWDS)after ultrafiltration pretreatment was investigated.The influence of pipeline hydraulic residence time(HRT)on disinfection efficiency,by-product formation,microbial activity,and biofilm growth were considered.The results show that both microbial activities and metabolite secretion were stimulated by increasing HRT,aggravating the potential risk of microbial pollution in DWDS.The enhanced microbial metabolism could further weaken disinfection efficiency by consuming extra residual Chlorine,after which the formation of disinfection by-products was facilitated.Residual Chlorine was found negatively correlated with HRT.With prolonging HRT from 5 to 40 h,the concentration of disinfection by-products(Chlorate,Chlorite,and Trichloromethane)was on a continuously increasing trend by 37%,140%,and 75%,respectively.But the water kept in pipeline still reliably satisfied the Standards for drinking water quality in China(GB5749–2022).Besides,more biofilm with denser morphologies developed on rubber pipeline gaskets rather than the iron/plastic ones.Rubber material was inappropriate for DWDS due to its potential risk of secondary biological pollution.Prolonging HRT also enhanced the accumulation of dominant bacteria(e.g.Bradyrhizobium and Obscuribacter)and decreased microbial diversity.展开更多
Although activated carbon filters are thought to be the best way to remove per-and polyfluorinated alkyl substances(PFAS),it is yet unknown how biofilms affect PFAS removal.This study first examined how the removal of...Although activated carbon filters are thought to be the best way to remove per-and polyfluorinated alkyl substances(PFAS),it is yet unknown how biofilms affect PFAS removal.This study first examined how the removal of PFAS in full-scale drinking water treatment plants(DWTPs)was impacted by biofilm from biological activated carbon(BAC)of varying depths and carbon ages.PFAS desorption from BAC was visible,but at this point,BAC could still remove dissolved organic matter(DOM)efficiently.Studies have demonstrated that the use of activated carbon filters can dramatically lower the content of PFAS in water,with the amount of PFAS reducing as the filter’s depth grows and its use duration increases.Additionally,pore-clogging becomes more noticeable as the biofilm ages,which reduces BAC’s capacity to eliminate PFAS and hinders PFAS desorption.Furthermore,the adsorption process of PFAS may be impeded by the secretion of biofilms,which are composed of proteins and polysaccharides.Based on the analysis above,it can be the adsorption of PFAS by BAC is significantly inhibited by biofilms,according to another research.This provides theoretical direction for improving the removal effectiveness of PFAS in DWTPs.展开更多
The effects of disinfectants and plasmid-based antibiotic resistance genes(ARGs)on the growth of microorganisms and the plasmid-mediated transfer of ARGs in the water and biofilm of the drinkingwater distribution syst...The effects of disinfectants and plasmid-based antibiotic resistance genes(ARGs)on the growth of microorganisms and the plasmid-mediated transfer of ARGs in the water and biofilm of the drinkingwater distribution system under simulated conditionswere explored.The heterotrophic plate count of the water in reactors with 0.1 mg/L NaClO and NH_(2)Cl was higher than in the control groups.Therewas no similar phenomenon in biofilm.In thewater of reactors containing NaClO,the aphA and bla geneswere lower than in the antibiotic resistant bacteria group,while both genes were higher in the water of reactors with NH_(2)Cl than in the control group.Chloramine may promote the transfer of ARGs in the water phase.Both genes in the biofilm of the reactors containing chlorine were lower than the control group.Correlation analysis between ARGs and water quality parameters revealed that the copy numbers of the aphA gene were significantly positively correlated with the copy numbers of the bla gene in water and significantly negatively correlated in biofilm(p<0.05).The results of the sequencing assay showed that bacteria in the biofilm,in the presence of disinfectant,were primarily Gram-negative.1.0 mg/L chlorine decreased the diversity of the community in the biofilm.The relative abundance of some bacteria that may undergo transfer increased in the biofilm of the reactor containing 0.1 mg/L chlorine.展开更多
Developing methods for detection contaminants in drinking water is essential to ensuring that safe and acceptable qual-ity drinking water is delivered to consumers.While manganese(Mn)was previously known only as a mer...Developing methods for detection contaminants in drinking water is essential to ensuring that safe and acceptable qual-ity drinking water is delivered to consumers.While manganese(Mn)was previously known only as a mere aesthetic issue,recent epidemiological data has shown to have negative neurological effects on humans,especially on children,prompting new health-based guidelines by Health Canada and the World Health Organization.In drinking water,Mn exists predomi-nantly as Mn(II)and Mn(IV),and is regulated based on total Mn levels.Interestingly,measurement of Mn particulate using electroanalytical methods has not yet been reported in the literature.Herein,a digestion procedure for insoluble manga-nese dioxide(MnO_(2))using ferrous(Fe^(2+))ions was optimized in preparation for Mn detection by cyclic voltammetry(CV).Digestion conditions including concentration of Fe^(2+)ions,pH and digestion time were explored and optimized.Digestion of MnO_(2)was found to be successful in both perfect and imperfect stoichiometric ratios;however,digestion was shown to be most effective in perfect stoichiometric conditions.CV proved to be an effective technique for the detection of different particulate Mn concentrations with good reproducibility using glassy carbon electrodes.According to the CV data,the detection limits of 0.3 mmol·L^(-1)and 0.1 mmol·L^(-1)for MnO_(2)were determined after the digestion time of 4.5 h and 24 h,re-spectively.The digestion method,in addition to CV detection,was found to be impacted by the presences of Cu^(2+)and Fe^(3+)ions.This interference suggests that this method may offer value as a multi-plexed technique.The Mn reduction signal was found to be enhanced in the presence of Mn^(2+),indicating that this method has the potential to be used to detect soluble and insoluble Mn species simultaneously.These digestion and detection methods are simple and reproducible methods which introduce the opportunity for total Mn detection in drinking water.展开更多
The global incidence of breast cancer remains high and is increasing annually in some regions.Despite the variety of current treatments for breast cancer,the preventive and therapeutic effects are still limited due to...The global incidence of breast cancer remains high and is increasing annually in some regions.Despite the variety of current treatments for breast cancer,the preventive and therapeutic effects are still limited due to the highly heterogeneous nature and complex biological mechanisms of breast cancer.In recent years,tea consumption has emerged as a research focus due to its possible anti-cancer properties.Numerous preclinical studies have demonstrated that regular tea intake could potentially curb the progression of breast cancer by influencing various biological mechanisms,including signaling pathways,cell cycle regulation,and immune system responses,among others.Nonetheless,the findings from epidemiological studies show considerable variability,and the connection between tea drinking and both the risk and outlook for breast cancer is shaped by numerous elements.These include the specific type of tea consumed,the quantity consumed,individual genetic variations,and environmental influences.This article summarizes the current research findings and delves into the connection between tea consumption and the risk as well as the prognosis of breast cancer among different regional populations.Meanwhile,it expounds on the potential molecular biological mechanisms behind it.The aim is to offer a theoretical foundation for the personalized prevention and treatment of breast cancer.展开更多
Cyclic volatile methyl siloxanes(cVMSs)are widely used in industrial and consumer products because of their thermal stability,low reactivity,and reduced surface tension[1].Their extensive use has resulted in environme...Cyclic volatile methyl siloxanes(cVMSs)are widely used in industrial and consumer products because of their thermal stability,low reactivity,and reduced surface tension[1].Their extensive use has resulted in environmental pollution globally.Recognized as very persistent and very bioaccumulative(vPvB),compounds such as octamethylcyclotetrasiloxane(D4),decamethylcyclopentasiloxane(D5),and dodecamethylcyclohexasiloxane(D6)are regulated in the European Union[2]and are monitored worldwide.展开更多
Organic amine pesticides(OAPs)are widely used in modern agriculture and these compounds can contaminate drinking water sources in different ways.However,there is a lack of data on the occurrence of OAPs in drinking wa...Organic amine pesticides(OAPs)are widely used in modern agriculture and these compounds can contaminate drinking water sources in different ways.However,there is a lack of data on the occurrence of OAPs in drinking water and their potential human health risks.In this study,tapwater(TW)and bottledwater(BW)sampleswere collected from eight cities in the Yangtze River Delta urban agglomeration in China,and their OAP levelswere analyzed using high-throughput organic analysis testing coupled with high-volume solid-phase extraction(Hi-throat/Hi-volume SPE techniques).This study is the first to systematically characterize the trace levels of OAPs in drinking water in China.Our findings indicated that the total concentration of OAPs(OAPs)in TW(average 11.06±4.99 ng/L)was 29.4%higher than in BW(average 8.55±3.98 ng/L)and fewer kinds(7)of OAPs were detected in BW.Furthermore,the long-term intake of TW in some areas was linked to carcinogenic risks even at an acceptable OAP range,particularly in males,with molinate being the major contributor(61.3%)to OAP exposure.Further analysis revealed that the occurrence and health risks of OAPs in drinking water were mainly influenced by the quality of water sources and the technologies adopted in drinking water treatment plants(DWTPs).Furthermore,our findings demonstrated that advanced treatment technologies such as nanofiltration could more effectively remove OAPs in raw water(up to 87.5%).Therefore,our findings highlighted the importance of selecting appropriate advanced treatment technologies in DWTPs.展开更多
Pharmaceuticals and personal care products(PPCPs)are receiving attention as emerging pollutants due to their extensive applications and persistent emissions.The Qiantang River Basin,a representative region in eastern ...Pharmaceuticals and personal care products(PPCPs)are receiving attention as emerging pollutants due to their extensive applications and persistent emissions.The Qiantang River Basin,a representative region in eastern China that relies on surface water for drinking purposes,experiences the movement and accumulation of PPCPs in its water and sediment,which can directly affect the safety of drinking water in the basin.This study focuses on the Qiantang River Basin’s surface water,sediment,and drinking water to determine the occurrence and potential risks of 31 PPCPs.It aims to address whether PPCPs in the environment could migrate and accumulate,thereby affecting human health.The findings indicated that PPCPs are ubiquitous in various environmental media,with surface and pore water showing distinct spatial distribution characteristics,specifically,concentrations escalated with urban scale expansion,indicating that domestic sewage discharge is the primary source of PPCP input.Bisphenol A(BPA),ketoprofen(KTP),and diethyltoluamide(DEET)were the primary contaminants.The movement of PPCPs within the surface water-sediment-pore water system was affected by various circumstances.Substances like Sulfamethoxazole(SMX)(RQ>103)and KTP(RQ=22.3)present in surface water and sediment pose significant ecological concerns,and KTP and atrazine(ATZ)(0.6<RQ<2.1)also pose a high risk in drinking water.This study performed an extensive analysis of the distribution and risks associated with typical PPCPs in the Qiantang River Basin,offering a scientific foundation and theoretical support for research on the environmental behavior of PPCPs in this area and the development of targeted pollution control strategies.展开更多
Objective:To explore the clinical efficacy of traditional Chinese medicine Fuzheng Quxie tea drinking package in the treatment of Zhengxu Xielian type cancer.Methods:In this study,50 cases of Zhengxu Xielian type canc...Objective:To explore the clinical efficacy of traditional Chinese medicine Fuzheng Quxie tea drinking package in the treatment of Zhengxu Xielian type cancer.Methods:In this study,50 cases of Zhengxu Xielian type cancer admitted to our hospital from January 2020 to December 2021 were selected.They were divided into a control group(n=25)and a treatment group(n=25)according to the random number table method.The control group received conventional symptomatic treatment plus adjuvant therapy for cancer while the treatment group received traditional Chinese medicine Fuzheng Quxie tea drinking package plus conventional symptomatic treatment and adjuvant cancer therapy.Tumor marker indexes,quality of life scores,and fatigue scores before and after treatment were compared and analyzed between the two groups.Results:After treatment,the CEA,CA125,and NSE indexes in the treatment group were lower than those in the control group,and the differences were statistically significant(P<0.05).After treatment,the quality of life scores of the treatment group were better,and the data between the two groups were statistically significant(P<0.05).After treatment,the fatigue score of the observation group was significantly lower at 67.56±4.69 compared to 110.59±10.59 in the control group(t=18.576,P<0.05).Conclusion:The treatment of Zhengxu Xielian type cancer patients with traditional Chinese medicine Fuzheng Quxie tea drinking package can significantly reduce tumor marker indexes,improve patients’quality of life,and reduce fatigue,which has clinical significance.展开更多
This study assesses the impact of on-site sanitation practices on the bacteriological quality of borehole water in the outlying neighborhoods of the 7th arrondissement of N'Djamena.To this end,sixteen(16)water sam...This study assesses the impact of on-site sanitation practices on the bacteriological quality of borehole water in the outlying neighborhoods of the 7th arrondissement of N'Djamena.To this end,sixteen(16)water samples were collected from 16 boreholes for physical and microbiological analyses,combined with piezometric sampling.The results show the presence of Escherichia coli in five of the 16 boreholes.Total coliforms and total aerobic bacteria were detected in all sampled boreholes.Fecal enterococci were found in only one borehole.The presence of these microorganisms,indicators of fecal contamination,in the samples reveals the link between the sampled water points and the wastewater treatment facilities.The piezometric map identified three areas of depression,two areas of high groundwater,and several low piezometric levels.展开更多
Rivers are essential for water supply,agriculture,hydropower,and biodiversity,yet they face increasing threats from climate change and pollution globally.The Koshi River Basin,spanning China,Nepal,and India,is a trans...Rivers are essential for water supply,agriculture,hydropower,and biodiversity,yet they face increasing threats from climate change and pollution globally.The Koshi River Basin,spanning China,Nepal,and India,is a transboundary basin that includes glacier-fed headwaters and densely populated downstream regions.This study investigates the hydrogeochemistry and water quality dynamics of the basin,focusing on seasonal and spatial variations and their implications for drinking and irrigation suitability.A total of 117 water samples from different segments of the basin were analyzed across premonsoon,monsoon,and post-monsoon seasons using in-situ,laboratory tests,and multivariate statistical methods.The results indicated that carbonate and silicate weathering were the dominant sources of solutes in the study region,with Ca^(2+)and HCO_(3)^(-)being the major ionic constituents.Seasonal variations revealed higher ionic concentrations in pre-and postmonsoon periods due to increased mineralization,while monsoonal dilution significantly reduced solute loads.Spatially,the higher hydrogeochemistry index in the upstream and lower values in downstream tributaries indicate intensive weathering in the headwaters but are further diluted by melting water and precipitation downstream.Inversely,higher pollution risks only appeared in downstream areas,where NO_(3)^(-)suggested agricultural runoff and wastewater intrusion.Water quality index<50 classified most river segments as suitable for drinking,while sodium adsorption ratio<1 confirmed irrigation suitability,except in some segments of the downstream zones with higher anthropogenic influence based on major ions.This study also supports Sustainable Development Goal 6(clean water and sanitation),13(climate action),and 15(life on land)by providing critical insights into water quality dynamics and informing sustainable water management strategies applicable to other glacier-fed river basins worldwide.展开更多
Although progress has been made nationally in terms of drinking water coverage,access remains a significant challenge in Togo’s secondary cities,particularly in Noèpéand Kovié.These areas are experienc...Although progress has been made nationally in terms of drinking water coverage,access remains a significant challenge in Togo’s secondary cities,particularly in Noèpéand Kovié.These areas are experiencing rapid urbanization and sustained population growth,which is putting increasing pressure on often dilapidated infrastructure.This study aims to examine the institutional,regulatory and organizational mechanisms that shape water governance in Noèpéand Kovié,to identify the main obstacles and potential pathways towards equitable and sustainable access to drinking water.The research combined a literature review with qualitative fieldwork,including 67 semi-structured interviews and focus groups with institutional actors,municipal authorities and community association.Thematic analysis was used to triangulate institutional discourse,policy documents and community perspectives.The findings reveal that governance is hindered by institutional fragmentation,weak inter-institutional coordination,compounded by centralized governance.Community-based models,although widespread,suffer from lack of professionalization,financial fragility,weak community participation and conflicts interest.Infrastructure deficits,dependence on ad hoc external funding,and limited regulation exacerbate service inequalities.To address these challenges,this study concludes that water governance in secondary cities must be adapted to institutional and regulatory frameworks while taking local specifics into account.Strengthening institutional and community capacities,updating stakeholder mapping,developing participatory governance mechanisms and establishing shared governance mechanisms are essential.Local master plan aligned with urban planning strategies are recommended to anticipate demographic pressures and climate variability.Such reforms would help to ensure sustainable access to drinking water.展开更多
Whipped cream is a delicious topping.You can make it at home or buy it in a can.People often put it on desserts such as cakes and pies.Whipped cream is great on ice cream and fruit,too.Do you like cream puffs?Some hav...Whipped cream is a delicious topping.You can make it at home or buy it in a can.People often put it on desserts such as cakes and pies.Whipped cream is great on ice cream and fruit,too.Do you like cream puffs?Some have whipped cream in them.Whipped cream is also good on hot chocolate and coffee.So,enjoy whipped cream on desserts and hot drinks today.It's National Whipped Cream Day!展开更多
Background: Post-workout supplementation has been used in athletes and recreational exercisers;however, responses between normal and overweight individuals on exercise performance and muscle recovery are less known.Me...Background: Post-workout supplementation has been used in athletes and recreational exercisers;however, responses between normal and overweight individuals on exercise performance and muscle recovery are less known.Methods: Normal and overweight young adult males(21 subjects/group) participated in resistance and fatiguing exercises before receiving post-workout supplements: placebo, coenzyme Q10(CoQ10), or sports drink in a crossover design. Resistance exercises included upper body exercise(bench press, upright row, and standing shoulder press) and lower body exercise(dead lift, back squat, and front squat) at 75% of one-repetition maximum(1 RM). Fatiguing exercise was performed on a cycle ergometer with 3 min of all-out effort at 3.5% of body mass. Participants consumed post-workout supplements within 10 min of exercise completion and repeated-bout exercise was performed 1 h later, followed by cardiovascular responses, urinary biomarkers, and delayed onset muscle soreness(DOMS) assessments.Results: There were effects of overweight on resistance exercise volume, critical power, fatigue index, and postexercise diastolic blood pressure(DBP). However, no differences in urinary biomarkers of muscle damage(potassium and creatinine) or DOMS between normal and overweight individuals. After supplementation, CoQ10 and sports drink increased resistance exercise volume regardless of body mass and increased critical power in the normal group. Additionally, CoQ10 supplementation was associated with a reduction in urinary biomarkers and DOMS in both groups.Conclusion: These findings are beneficial for sport scientists, nutritionists, and exercise physiologists in guiding post-workout supplementation with CoQ10 and sports drink to improve exercise performance and muscle recovery in normal and overweight individuals.展开更多
Problems due to the taste and odor in drinking water are common in treatment facilities around the world. Taste and odor are perceived by the public as the primary indicators of the safely and acceptability of drinkin...Problems due to the taste and odor in drinking water are common in treatment facilities around the world. Taste and odor are perceived by the public as the primary indicators of the safely and acceptability of drinking water and are mainly caused by the presence of two semi-volatile compounds - 2-methyl isobomeol （MIB） and geosmin. A review of these two taste and odor causing compounds in drinking water is presented. The sources for the formation of these compounds in water are discussed alongwith the health and regulatory implications. The recent developments in the analysis of MIB/geosmin in water which have allowed for rapid measurements in the nanogram per liter concentrations are also discussed. This review focuses on the relevant treatment alternatives, that are described in detail with emphasis on their respective advantages and problems associated with their implementation in a full- scale facility. Conventional treatment processes in water treatment plants, such as coagulation, sedimentation and chlorination have been found to be ineffective for removal of M1B/geosmin. Studies have shown powdered activated carbon, ozonation and biofiltration to be effective in treatment of these two compounds. Although some of these technologies are more effective and show more promise than the others, much work remains to be done to optimize these technologies so that they can be retrofitted or installed with minimal impact on the overall operation and effectiveness of the treatment system.展开更多
In recent years, membrane ultrafiltration （UF） of surface water for drinking water treatment has become a more attractive technology worldwide as a possible alternative treatment to conventional clarification. To ev...In recent years, membrane ultrafiltration （UF） of surface water for drinking water treatment has become a more attractive technology worldwide as a possible alternative treatment to conventional clarification. To evaluate the performance of ultrafiltration membranes for treatment of surface water in North China, a 48-m^2 low pressure hollow fiber membrane ultrafiltration pilot plant was constructed. Ultrafiltration was operated in cross-flow and with powdered activated carbon （PAC） adsorption. Turbidity was almost completely removed to less than 0.2 NTU （below Chinese standard 1 NTU）. It was found that PAC addition enhanced organic matter removal. The combined process of PAC/UF allowed to 41% removal of CODMn, 46% removal of DOC and 57% decrease in UV254 absorbance. The elimination of particles, from average 12000/ml in the raw water to approximately 15/ml in the permeated, was observed. When PAC concentration was below 30 mg/L, backwashing could recovery the membrane flux with backwash interval/backwashing duration of 1/30.展开更多
AIM: To assess the risk of gastric cancer(GC) in relation to tobacco use and alcohol drinking in the Karunagappally cohort in Kerala, South India.METHODS: This study examined the association of tobacco use and alcohol...AIM: To assess the risk of gastric cancer(GC) in relation to tobacco use and alcohol drinking in the Karunagappally cohort in Kerala, South India.METHODS: This study examined the association of tobacco use and alcohol drinking with GC incidence among 65553 men aged 30-84 in the Karunagappally cohort. During the period from 1990-2009, 116 GC cases in the cohort were identified as incident cancers. These cases were identified from the populationbased cancer registry. Information regarding risk factors such as socioeconomic factors and tobacco and alcohol habits of cohort members were collected from the database of the baseline survey conducted during 1990-1997. The relative risks(RRs) and the corresponding 95% confidence intervals(95%CIs) fortobacco use were obtained from Poisson regression analysis of grouped survival data, considering age, follow-up period, occupation and education.RESULTS: Bidi smoking was associated with GC risk(P = 0.042). The RR comparing current versus never smokers was 1.6(95%CI: 1.0-2.5). GC risk was associated with the number of bidis smoked daily(P = 0.012) and with the duration of bidi smoking(P = 0.036). Those who started bidi smoking at younger ages were at an elevated GC risk; the RRs for those starting bidi smoking under the age of 18 and ages 18-22 were 2.0(95%CI: 1.0-3.9) and 1.8(95%CI: 1.1-2.9), respectively, when their risks were compared with lifetime non-smokers of bidis. Bidi smoking increased the risk of GC among never cigarette smokers more evidently(RR = 2.2; 95%CI: 1.3-4.0). GC risk increased with the cumulative amount of bidi smoking, which was calculated as the number of bidis smoked per day x years of smoking(bidi-year; P = 0.017). Cigarette smoking, tobacco chewing or alcohol drinking was not significantly associated with GC risk. CONCLUSION: Among a male cohort in South India, gastric cancer risk increased with the number and duration of bidi smoking.展开更多
Taste and odor （T＆O） problems in drinking water frequently occur because of many compounds present in the water, of which trans-1,10-dimethyl-trans-9-decalol （geosrnin） and 2-methylisoborneol （MIB） are well-kno...Taste and odor （T＆O） problems in drinking water frequently occur because of many compounds present in the water, of which trans-1,10-dimethyl-trans-9-decalol （geosrnin） and 2-methylisoborneol （MIB） are well-known. In this study, a fast and effective method was established for simultaneous determination of 10 T＆O compounds, including geosmin, MIB, 2,4,6-trichloroanisole （TCA）, 2-methylbenzofuran, 2-isopropyl-3-methoxypyrazine （IPMP）, 2-isobutyl-3-methoxypyrazine （IBMP）, cis-3-hexenyl acetate, trans,trans-2,4-heptadienal, trans, cis-2,6-nonadienal, and trans-2-decenal in water samples by headspace solid-phase microextraction （SPME） coupled with gas chromatography-mass spectrometry. An orthogonal array experimental design was used to optimize the effects of SPME fiber, extraction temperature, stirring rate, NaC1 content, extraction time, and desorption time. The limits of detection ranged from 0.1 to 73 ng/L were lower than or close to the odor threshold concentrations （OTCs）. All the 10 T＆O compounds were detected in the 14 water samples including surface water, treatment process water and tap water, taken from a waterworks in Lianyungang City, China. MIB and geosmin were detected in most samples at low concentration. Six T＆O compounds （IPMP, IBMP, trans,cis-2,6-nonadienal, 2-methylbenzofuran, trans-2-decenal, and TCA） were effectively decreased in water treatment process （sedimentation and filtration） that is different from cis-3-hexenyl acetate, MIB and geosmin. It is noted that the TCA concentrations at 15.9-122.3 ng/L and the trans,cis-2,6-nonadienal concentrations at 79.9-190.1 ng/L were over 10 times higher than their OTCs in tap water. The variation of the analytes in the all water samples, especially distribution system indicated that distribution system cannot be ignored as a T＆O compounds source.展开更多
A wide range of compounds with various structural features can cause taste and odor(T&O)problems in drinking water. It would be desirable to determine all of these compounds using a simple analytical method. In th...A wide range of compounds with various structural features can cause taste and odor(T&O)problems in drinking water. It would be desirable to determine all of these compounds using a simple analytical method. In this paper, a sensitive method combining liquid–liquid extraction(LLE) with gas chromatography-triple quadrupole tandem mass spectrometry(GC–MS/MS)was established to simultaneously analyze 51 odor-causing compounds in drinking water,including organic sulfides, aldehydes, benzenes, phenols, ethers, esters, ketones, nitrogenous heterocyclic compounds, 2-methylisoborneol and geosmin. Three deuterated analogs of target analytes, dimethyl disulfide-d6, benzaldehyde-d6 and o-cresol-3,4,5,6-d4,were used to correct the variations in recovery, and five isotope-labeled internal standards(4-chlorotoluene-d4, 1, 4-dichlorobenzene-d4, naphthalene-d8, acenaphthene-d10, phenanthrene-d10 respectively) were used prior to analysis to correct the variations arising from instrument fluctuations and injection errors. The calibration curves of the target compounds showed good linearity(R2> 0.99, level = 7),and method detection limits(MDLs) below 1/10 of the odor threshold concentrations were achieved for most of the odorants(0.10–20.55 ng/L). The average recoveries of most of the analytes in tap water samples were between 70% and 120%, and the method was reproducible(RSD < 20%, n = 7). Additionally, concentrations of odor-causing compounds in water samples collected from three drinking water treatment plants(DWTPs) were analyzed by this method.According to the results, dimethyl trisulfide, dimethyl disulfide and indole were considered to be the key odorants responsible for the swampy/septic odor. 2-Methylisoborneol and geosmin were detected as the main odor-causing compounds for musty/earthy odor in DWTP B.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52170070,52400022,and 52200088)the Youth S&T Talent Support Programme of Guangdong Provincial Association for Science and Technology(GDSTA)(No.SKXRC202406)+1 种基金the“One hundred Youth”Science and Technology Plan,Guangdong University of Technology,China(No.263113906)China Postdoctoral Science Foundation(No.2023M740754).
文摘In this study,the effects of low-dose sodium hypochlorite disinfection on water quality and biofilm growth in drinking water distribution systems(DWDS)after ultrafiltration pretreatment was investigated.The influence of pipeline hydraulic residence time(HRT)on disinfection efficiency,by-product formation,microbial activity,and biofilm growth were considered.The results show that both microbial activities and metabolite secretion were stimulated by increasing HRT,aggravating the potential risk of microbial pollution in DWDS.The enhanced microbial metabolism could further weaken disinfection efficiency by consuming extra residual Chlorine,after which the formation of disinfection by-products was facilitated.Residual Chlorine was found negatively correlated with HRT.With prolonging HRT from 5 to 40 h,the concentration of disinfection by-products(Chlorate,Chlorite,and Trichloromethane)was on a continuously increasing trend by 37%,140%,and 75%,respectively.But the water kept in pipeline still reliably satisfied the Standards for drinking water quality in China(GB5749–2022).Besides,more biofilm with denser morphologies developed on rubber pipeline gaskets rather than the iron/plastic ones.Rubber material was inappropriate for DWDS due to its potential risk of secondary biological pollution.Prolonging HRT also enhanced the accumulation of dominant bacteria(e.g.Bradyrhizobium and Obscuribacter)and decreased microbial diversity.
基金supported by the National Key Research and Development Program of China(No.2022YFC3203703)the National Natural Science Foundation of China(No.52270013).
文摘Although activated carbon filters are thought to be the best way to remove per-and polyfluorinated alkyl substances(PFAS),it is yet unknown how biofilms affect PFAS removal.This study first examined how the removal of PFAS in full-scale drinking water treatment plants(DWTPs)was impacted by biofilm from biological activated carbon(BAC)of varying depths and carbon ages.PFAS desorption from BAC was visible,but at this point,BAC could still remove dissolved organic matter(DOM)efficiently.Studies have demonstrated that the use of activated carbon filters can dramatically lower the content of PFAS in water,with the amount of PFAS reducing as the filter’s depth grows and its use duration increases.Additionally,pore-clogging becomes more noticeable as the biofilm ages,which reduces BAC’s capacity to eliminate PFAS and hinders PFAS desorption.Furthermore,the adsorption process of PFAS may be impeded by the secretion of biofilms,which are composed of proteins and polysaccharides.Based on the analysis above,it can be the adsorption of PFAS by BAC is significantly inhibited by biofilms,according to another research.This provides theoretical direction for improving the removal effectiveness of PFAS in DWTPs.
基金supported by the Natural Science Foundation of China(No.52070145,51778453).
文摘The effects of disinfectants and plasmid-based antibiotic resistance genes(ARGs)on the growth of microorganisms and the plasmid-mediated transfer of ARGs in the water and biofilm of the drinkingwater distribution system under simulated conditionswere explored.The heterotrophic plate count of the water in reactors with 0.1 mg/L NaClO and NH_(2)Cl was higher than in the control groups.Therewas no similar phenomenon in biofilm.In thewater of reactors containing NaClO,the aphA and bla geneswere lower than in the antibiotic resistant bacteria group,while both genes were higher in the water of reactors with NH_(2)Cl than in the control group.Chloramine may promote the transfer of ARGs in the water phase.Both genes in the biofilm of the reactors containing chlorine were lower than the control group.Correlation analysis between ARGs and water quality parameters revealed that the copy numbers of the aphA gene were significantly positively correlated with the copy numbers of the bla gene in water and significantly negatively correlated in biofilm(p<0.05).The results of the sequencing assay showed that bacteria in the biofilm,in the presence of disinfectant,were primarily Gram-negative.1.0 mg/L chlorine decreased the diversity of the community in the biofilm.The relative abundance of some bacteria that may undergo transfer increased in the biofilm of the reactor containing 0.1 mg/L chlorine.
基金financial support from the Natural Sciences and Engineering Research Council of Canada through the Discovery Grant programsupports from the Department of Chemistry,the Department of Civil Engineering,and Beaty Water Research Centre。
文摘Developing methods for detection contaminants in drinking water is essential to ensuring that safe and acceptable qual-ity drinking water is delivered to consumers.While manganese(Mn)was previously known only as a mere aesthetic issue,recent epidemiological data has shown to have negative neurological effects on humans,especially on children,prompting new health-based guidelines by Health Canada and the World Health Organization.In drinking water,Mn exists predomi-nantly as Mn(II)and Mn(IV),and is regulated based on total Mn levels.Interestingly,measurement of Mn particulate using electroanalytical methods has not yet been reported in the literature.Herein,a digestion procedure for insoluble manga-nese dioxide(MnO_(2))using ferrous(Fe^(2+))ions was optimized in preparation for Mn detection by cyclic voltammetry(CV).Digestion conditions including concentration of Fe^(2+)ions,pH and digestion time were explored and optimized.Digestion of MnO_(2)was found to be successful in both perfect and imperfect stoichiometric ratios;however,digestion was shown to be most effective in perfect stoichiometric conditions.CV proved to be an effective technique for the detection of different particulate Mn concentrations with good reproducibility using glassy carbon electrodes.According to the CV data,the detection limits of 0.3 mmol·L^(-1)and 0.1 mmol·L^(-1)for MnO_(2)were determined after the digestion time of 4.5 h and 24 h,re-spectively.The digestion method,in addition to CV detection,was found to be impacted by the presences of Cu^(2+)and Fe^(3+)ions.This interference suggests that this method may offer value as a multi-plexed technique.The Mn reduction signal was found to be enhanced in the presence of Mn^(2+),indicating that this method has the potential to be used to detect soluble and insoluble Mn species simultaneously.These digestion and detection methods are simple and reproducible methods which introduce the opportunity for total Mn detection in drinking water.
文摘The global incidence of breast cancer remains high and is increasing annually in some regions.Despite the variety of current treatments for breast cancer,the preventive and therapeutic effects are still limited due to the highly heterogeneous nature and complex biological mechanisms of breast cancer.In recent years,tea consumption has emerged as a research focus due to its possible anti-cancer properties.Numerous preclinical studies have demonstrated that regular tea intake could potentially curb the progression of breast cancer by influencing various biological mechanisms,including signaling pathways,cell cycle regulation,and immune system responses,among others.Nonetheless,the findings from epidemiological studies show considerable variability,and the connection between tea drinking and both the risk and outlook for breast cancer is shaped by numerous elements.These include the specific type of tea consumed,the quantity consumed,individual genetic variations,and environmental influences.This article summarizes the current research findings and delves into the connection between tea consumption and the risk as well as the prognosis of breast cancer among different regional populations.Meanwhile,it expounds on the potential molecular biological mechanisms behind it.The aim is to offer a theoretical foundation for the personalized prevention and treatment of breast cancer.
基金supported by the Shanghai 3-year Public Health Action Plan(grant number:GWVI-11.1-39).
文摘Cyclic volatile methyl siloxanes(cVMSs)are widely used in industrial and consumer products because of their thermal stability,low reactivity,and reduced surface tension[1].Their extensive use has resulted in environmental pollution globally.Recognized as very persistent and very bioaccumulative(vPvB),compounds such as octamethylcyclotetrasiloxane(D4),decamethylcyclopentasiloxane(D5),and dodecamethylcyclohexasiloxane(D6)are regulated in the European Union[2]and are monitored worldwide.
基金supported by the National Key Research and Development Program of China(No.2019YFD1100203).
文摘Organic amine pesticides(OAPs)are widely used in modern agriculture and these compounds can contaminate drinking water sources in different ways.However,there is a lack of data on the occurrence of OAPs in drinking water and their potential human health risks.In this study,tapwater(TW)and bottledwater(BW)sampleswere collected from eight cities in the Yangtze River Delta urban agglomeration in China,and their OAP levelswere analyzed using high-throughput organic analysis testing coupled with high-volume solid-phase extraction(Hi-throat/Hi-volume SPE techniques).This study is the first to systematically characterize the trace levels of OAPs in drinking water in China.Our findings indicated that the total concentration of OAPs(OAPs)in TW(average 11.06±4.99 ng/L)was 29.4%higher than in BW(average 8.55±3.98 ng/L)and fewer kinds(7)of OAPs were detected in BW.Furthermore,the long-term intake of TW in some areas was linked to carcinogenic risks even at an acceptable OAP range,particularly in males,with molinate being the major contributor(61.3%)to OAP exposure.Further analysis revealed that the occurrence and health risks of OAPs in drinking water were mainly influenced by the quality of water sources and the technologies adopted in drinking water treatment plants(DWTPs).Furthermore,our findings demonstrated that advanced treatment technologies such as nanofiltration could more effectively remove OAPs in raw water(up to 87.5%).Therefore,our findings highlighted the importance of selecting appropriate advanced treatment technologies in DWTPs.
基金jointly supported by the Open Research Fund of State Environmental Protection Key Laboratory of Drinking Water Source Protection,Chinese Research Academy of Environmental Sciences(2022YYSYKFYB07)the Fundamental Research Funds for the Central Publicinterest Scientific Institution(2022YSKY-07)the China Geological Survey Project(DD20211414).
文摘Pharmaceuticals and personal care products(PPCPs)are receiving attention as emerging pollutants due to their extensive applications and persistent emissions.The Qiantang River Basin,a representative region in eastern China that relies on surface water for drinking purposes,experiences the movement and accumulation of PPCPs in its water and sediment,which can directly affect the safety of drinking water in the basin.This study focuses on the Qiantang River Basin’s surface water,sediment,and drinking water to determine the occurrence and potential risks of 31 PPCPs.It aims to address whether PPCPs in the environment could migrate and accumulate,thereby affecting human health.The findings indicated that PPCPs are ubiquitous in various environmental media,with surface and pore water showing distinct spatial distribution characteristics,specifically,concentrations escalated with urban scale expansion,indicating that domestic sewage discharge is the primary source of PPCP input.Bisphenol A(BPA),ketoprofen(KTP),and diethyltoluamide(DEET)were the primary contaminants.The movement of PPCPs within the surface water-sediment-pore water system was affected by various circumstances.Substances like Sulfamethoxazole(SMX)(RQ>103)and KTP(RQ=22.3)present in surface water and sediment pose significant ecological concerns,and KTP and atrazine(ATZ)(0.6<RQ<2.1)also pose a high risk in drinking water.This study performed an extensive analysis of the distribution and risks associated with typical PPCPs in the Qiantang River Basin,offering a scientific foundation and theoretical support for research on the environmental behavior of PPCPs in this area and the development of targeted pollution control strategies.
基金Dai Yongfu’s Observation on the Clinical Effect of Traditional Chinese Medicine Fuzheng Quxie Tea Drinking Package in Treating Cancer of Zhengxu Xielian Type-A Key Scientific Research Project of the Ningxia Health and Family Planning Commission(Project No.:2019-NW-004).
文摘Objective:To explore the clinical efficacy of traditional Chinese medicine Fuzheng Quxie tea drinking package in the treatment of Zhengxu Xielian type cancer.Methods:In this study,50 cases of Zhengxu Xielian type cancer admitted to our hospital from January 2020 to December 2021 were selected.They were divided into a control group(n=25)and a treatment group(n=25)according to the random number table method.The control group received conventional symptomatic treatment plus adjuvant therapy for cancer while the treatment group received traditional Chinese medicine Fuzheng Quxie tea drinking package plus conventional symptomatic treatment and adjuvant cancer therapy.Tumor marker indexes,quality of life scores,and fatigue scores before and after treatment were compared and analyzed between the two groups.Results:After treatment,the CEA,CA125,and NSE indexes in the treatment group were lower than those in the control group,and the differences were statistically significant(P<0.05).After treatment,the quality of life scores of the treatment group were better,and the data between the two groups were statistically significant(P<0.05).After treatment,the fatigue score of the observation group was significantly lower at 67.56±4.69 compared to 110.59±10.59 in the control group(t=18.576,P<0.05).Conclusion:The treatment of Zhengxu Xielian type cancer patients with traditional Chinese medicine Fuzheng Quxie tea drinking package can significantly reduce tumor marker indexes,improve patients’quality of life,and reduce fatigue,which has clinical significance.
文摘This study assesses the impact of on-site sanitation practices on the bacteriological quality of borehole water in the outlying neighborhoods of the 7th arrondissement of N'Djamena.To this end,sixteen(16)water samples were collected from 16 boreholes for physical and microbiological analyses,combined with piezometric sampling.The results show the presence of Escherichia coli in five of the 16 boreholes.Total coliforms and total aerobic bacteria were detected in all sampled boreholes.Fecal enterococci were found in only one borehole.The presence of these microorganisms,indicators of fecal contamination,in the samples reveals the link between the sampled water points and the wastewater treatment facilities.The piezometric map identified three areas of depression,two areas of high groundwater,and several low piezometric levels.
基金financially supported by the CASANSO Sustainable Development Research Project(Grant No.CAS-ANSO-SDRP-2024-05)the Research Directorate,Rector’s Office Tribhuvan University,Nepal(TU-NPAR-079/80-ERG-08)。
文摘Rivers are essential for water supply,agriculture,hydropower,and biodiversity,yet they face increasing threats from climate change and pollution globally.The Koshi River Basin,spanning China,Nepal,and India,is a transboundary basin that includes glacier-fed headwaters and densely populated downstream regions.This study investigates the hydrogeochemistry and water quality dynamics of the basin,focusing on seasonal and spatial variations and their implications for drinking and irrigation suitability.A total of 117 water samples from different segments of the basin were analyzed across premonsoon,monsoon,and post-monsoon seasons using in-situ,laboratory tests,and multivariate statistical methods.The results indicated that carbonate and silicate weathering were the dominant sources of solutes in the study region,with Ca^(2+)and HCO_(3)^(-)being the major ionic constituents.Seasonal variations revealed higher ionic concentrations in pre-and postmonsoon periods due to increased mineralization,while monsoonal dilution significantly reduced solute loads.Spatially,the higher hydrogeochemistry index in the upstream and lower values in downstream tributaries indicate intensive weathering in the headwaters but are further diluted by melting water and precipitation downstream.Inversely,higher pollution risks only appeared in downstream areas,where NO_(3)^(-)suggested agricultural runoff and wastewater intrusion.Water quality index<50 classified most river segments as suitable for drinking,while sodium adsorption ratio<1 confirmed irrigation suitability,except in some segments of the downstream zones with higher anthropogenic influence based on major ions.This study also supports Sustainable Development Goal 6(clean water and sanitation),13(climate action),and 15(life on land)by providing critical insights into water quality dynamics and informing sustainable water management strategies applicable to other glacier-fed river basins worldwide.
基金supported by the World Bank Group through the Regional Centre of Excellence on Sustainable Cities in Africa(CERViDA-DOUNEDON),grant numbers 6512-TG and 5360-TG.
文摘Although progress has been made nationally in terms of drinking water coverage,access remains a significant challenge in Togo’s secondary cities,particularly in Noèpéand Kovié.These areas are experiencing rapid urbanization and sustained population growth,which is putting increasing pressure on often dilapidated infrastructure.This study aims to examine the institutional,regulatory and organizational mechanisms that shape water governance in Noèpéand Kovié,to identify the main obstacles and potential pathways towards equitable and sustainable access to drinking water.The research combined a literature review with qualitative fieldwork,including 67 semi-structured interviews and focus groups with institutional actors,municipal authorities and community association.Thematic analysis was used to triangulate institutional discourse,policy documents and community perspectives.The findings reveal that governance is hindered by institutional fragmentation,weak inter-institutional coordination,compounded by centralized governance.Community-based models,although widespread,suffer from lack of professionalization,financial fragility,weak community participation and conflicts interest.Infrastructure deficits,dependence on ad hoc external funding,and limited regulation exacerbate service inequalities.To address these challenges,this study concludes that water governance in secondary cities must be adapted to institutional and regulatory frameworks while taking local specifics into account.Strengthening institutional and community capacities,updating stakeholder mapping,developing participatory governance mechanisms and establishing shared governance mechanisms are essential.Local master plan aligned with urban planning strategies are recommended to anticipate demographic pressures and climate variability.Such reforms would help to ensure sustainable access to drinking water.
文摘Whipped cream is a delicious topping.You can make it at home or buy it in a can.People often put it on desserts such as cakes and pies.Whipped cream is great on ice cream and fruit,too.Do you like cream puffs?Some have whipped cream in them.Whipped cream is also good on hot chocolate and coffee.So,enjoy whipped cream on desserts and hot drinks today.It's National Whipped Cream Day!
基金supported by the MUSC-TU Scholarship for Human Resource Development in Science & Technology in the Remembrance of Late King Rama Ⅸ of ThailandPartial Funding for Graduate Student Thesis for the Year 2021 by the Faculty of Graduate Studies and Graduate Studies of Mahidol University Alumni Association。
文摘Background: Post-workout supplementation has been used in athletes and recreational exercisers;however, responses between normal and overweight individuals on exercise performance and muscle recovery are less known.Methods: Normal and overweight young adult males(21 subjects/group) participated in resistance and fatiguing exercises before receiving post-workout supplements: placebo, coenzyme Q10(CoQ10), or sports drink in a crossover design. Resistance exercises included upper body exercise(bench press, upright row, and standing shoulder press) and lower body exercise(dead lift, back squat, and front squat) at 75% of one-repetition maximum(1 RM). Fatiguing exercise was performed on a cycle ergometer with 3 min of all-out effort at 3.5% of body mass. Participants consumed post-workout supplements within 10 min of exercise completion and repeated-bout exercise was performed 1 h later, followed by cardiovascular responses, urinary biomarkers, and delayed onset muscle soreness(DOMS) assessments.Results: There were effects of overweight on resistance exercise volume, critical power, fatigue index, and postexercise diastolic blood pressure(DBP). However, no differences in urinary biomarkers of muscle damage(potassium and creatinine) or DOMS between normal and overweight individuals. After supplementation, CoQ10 and sports drink increased resistance exercise volume regardless of body mass and increased critical power in the normal group. Additionally, CoQ10 supplementation was associated with a reduction in urinary biomarkers and DOMS in both groups.Conclusion: These findings are beneficial for sport scientists, nutritionists, and exercise physiologists in guiding post-workout supplementation with CoQ10 and sports drink to improve exercise performance and muscle recovery in normal and overweight individuals.
文摘Problems due to the taste and odor in drinking water are common in treatment facilities around the world. Taste and odor are perceived by the public as the primary indicators of the safely and acceptability of drinking water and are mainly caused by the presence of two semi-volatile compounds - 2-methyl isobomeol （MIB） and geosmin. A review of these two taste and odor causing compounds in drinking water is presented. The sources for the formation of these compounds in water are discussed alongwith the health and regulatory implications. The recent developments in the analysis of MIB/geosmin in water which have allowed for rapid measurements in the nanogram per liter concentrations are also discussed. This review focuses on the relevant treatment alternatives, that are described in detail with emphasis on their respective advantages and problems associated with their implementation in a full- scale facility. Conventional treatment processes in water treatment plants, such as coagulation, sedimentation and chlorination have been found to be ineffective for removal of M1B/geosmin. Studies have shown powdered activated carbon, ozonation and biofiltration to be effective in treatment of these two compounds. Although some of these technologies are more effective and show more promise than the others, much work remains to be done to optimize these technologies so that they can be retrofitted or installed with minimal impact on the overall operation and effectiveness of the treatment system.
基金Project supported by the Hi-Tech Research and Development Program (863) of China (No. 2002AA601140)the Science and Technology Commission of Shanghai Municipality (No. 052312008)the National Eleven Five-Year Scientific and Technical Support Plans (No. 2006BAJ08B06, 2006BAJ08B02).
文摘In recent years, membrane ultrafiltration （UF） of surface water for drinking water treatment has become a more attractive technology worldwide as a possible alternative treatment to conventional clarification. To evaluate the performance of ultrafiltration membranes for treatment of surface water in North China, a 48-m^2 low pressure hollow fiber membrane ultrafiltration pilot plant was constructed. Ultrafiltration was operated in cross-flow and with powdered activated carbon （PAC） adsorption. Turbidity was almost completely removed to less than 0.2 NTU （below Chinese standard 1 NTU）. It was found that PAC addition enhanced organic matter removal. The combined process of PAC/UF allowed to 41% removal of CODMn, 46% removal of DOC and 57% decrease in UV254 absorbance. The elimination of particles, from average 12000/ml in the raw water to approximately 15/ml in the permeated, was observed. When PAC concentration was below 30 mg/L, backwashing could recovery the membrane flux with backwash interval/backwashing duration of 1/30.
基金Supported by Department of Atomic Energy,Government of Indiathe Health Research Foundation,JapanGrants-inAid for Scientific Research on Priority Areas of the Ministry of Education,Culture,Sports,Science and Technology of Japan,No.12218231 and No.1701503
文摘AIM: To assess the risk of gastric cancer(GC) in relation to tobacco use and alcohol drinking in the Karunagappally cohort in Kerala, South India.METHODS: This study examined the association of tobacco use and alcohol drinking with GC incidence among 65553 men aged 30-84 in the Karunagappally cohort. During the period from 1990-2009, 116 GC cases in the cohort were identified as incident cancers. These cases were identified from the populationbased cancer registry. Information regarding risk factors such as socioeconomic factors and tobacco and alcohol habits of cohort members were collected from the database of the baseline survey conducted during 1990-1997. The relative risks(RRs) and the corresponding 95% confidence intervals(95%CIs) fortobacco use were obtained from Poisson regression analysis of grouped survival data, considering age, follow-up period, occupation and education.RESULTS: Bidi smoking was associated with GC risk(P = 0.042). The RR comparing current versus never smokers was 1.6(95%CI: 1.0-2.5). GC risk was associated with the number of bidis smoked daily(P = 0.012) and with the duration of bidi smoking(P = 0.036). Those who started bidi smoking at younger ages were at an elevated GC risk; the RRs for those starting bidi smoking under the age of 18 and ages 18-22 were 2.0(95%CI: 1.0-3.9) and 1.8(95%CI: 1.1-2.9), respectively, when their risks were compared with lifetime non-smokers of bidis. Bidi smoking increased the risk of GC among never cigarette smokers more evidently(RR = 2.2; 95%CI: 1.3-4.0). GC risk increased with the cumulative amount of bidi smoking, which was calculated as the number of bidis smoked per day x years of smoking(bidi-year; P = 0.017). Cigarette smoking, tobacco chewing or alcohol drinking was not significantly associated with GC risk. CONCLUSION: Among a male cohort in South India, gastric cancer risk increased with the number and duration of bidi smoking.
基金supported by the National Natural Science Foundation of China(No.21007077,51290283)the Ministry of Water Resources’ Special Funds for Scientific Research on Public Causes(No.201201032)
文摘Taste and odor （T＆O） problems in drinking water frequently occur because of many compounds present in the water, of which trans-1,10-dimethyl-trans-9-decalol （geosrnin） and 2-methylisoborneol （MIB） are well-known. In this study, a fast and effective method was established for simultaneous determination of 10 T＆O compounds, including geosmin, MIB, 2,4,6-trichloroanisole （TCA）, 2-methylbenzofuran, 2-isopropyl-3-methoxypyrazine （IPMP）, 2-isobutyl-3-methoxypyrazine （IBMP）, cis-3-hexenyl acetate, trans,trans-2,4-heptadienal, trans, cis-2,6-nonadienal, and trans-2-decenal in water samples by headspace solid-phase microextraction （SPME） coupled with gas chromatography-mass spectrometry. An orthogonal array experimental design was used to optimize the effects of SPME fiber, extraction temperature, stirring rate, NaC1 content, extraction time, and desorption time. The limits of detection ranged from 0.1 to 73 ng/L were lower than or close to the odor threshold concentrations （OTCs）. All the 10 T＆O compounds were detected in the 14 water samples including surface water, treatment process water and tap water, taken from a waterworks in Lianyungang City, China. MIB and geosmin were detected in most samples at low concentration. Six T＆O compounds （IPMP, IBMP, trans,cis-2,6-nonadienal, 2-methylbenzofuran, trans-2-decenal, and TCA） were effectively decreased in water treatment process （sedimentation and filtration） that is different from cis-3-hexenyl acetate, MIB and geosmin. It is noted that the TCA concentrations at 15.9-122.3 ng/L and the trans,cis-2,6-nonadienal concentrations at 79.9-190.1 ng/L were over 10 times higher than their OTCs in tap water. The variation of the analytes in the all water samples, especially distribution system indicated that distribution system cannot be ignored as a T＆O compounds source.
基金supported by the Major Science and Technology Program for Water Pollution Control and Treatment(Nos.2015ZX07406001 and 2017ZX07207004)the National Natural Science Foundation of China(Nos.51778602 and 21707117)the Major Project of Key Laboratory of Drinking Water Science and Technology,Research Center for EcoEnvironmental Sciences,CAS(No.17Z02KLDWST)
文摘A wide range of compounds with various structural features can cause taste and odor(T&O)problems in drinking water. It would be desirable to determine all of these compounds using a simple analytical method. In this paper, a sensitive method combining liquid–liquid extraction(LLE) with gas chromatography-triple quadrupole tandem mass spectrometry(GC–MS/MS)was established to simultaneously analyze 51 odor-causing compounds in drinking water,including organic sulfides, aldehydes, benzenes, phenols, ethers, esters, ketones, nitrogenous heterocyclic compounds, 2-methylisoborneol and geosmin. Three deuterated analogs of target analytes, dimethyl disulfide-d6, benzaldehyde-d6 and o-cresol-3,4,5,6-d4,were used to correct the variations in recovery, and five isotope-labeled internal standards(4-chlorotoluene-d4, 1, 4-dichlorobenzene-d4, naphthalene-d8, acenaphthene-d10, phenanthrene-d10 respectively) were used prior to analysis to correct the variations arising from instrument fluctuations and injection errors. The calibration curves of the target compounds showed good linearity(R2> 0.99, level = 7),and method detection limits(MDLs) below 1/10 of the odor threshold concentrations were achieved for most of the odorants(0.10–20.55 ng/L). The average recoveries of most of the analytes in tap water samples were between 70% and 120%, and the method was reproducible(RSD < 20%, n = 7). Additionally, concentrations of odor-causing compounds in water samples collected from three drinking water treatment plants(DWTPs) were analyzed by this method.According to the results, dimethyl trisulfide, dimethyl disulfide and indole were considered to be the key odorants responsible for the swampy/septic odor. 2-Methylisoborneol and geosmin were detected as the main odor-causing compounds for musty/earthy odor in DWTP B.
