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Emerging Contaminants 2019年第1期5卷 173-178页

作者： Tlou B.Chokwe jonathan o.okonkwo Scientific Services Rand WaterP.O.Box 3526Vereeniging1930South Africa Department of Water Environmental and Earth SciencesTshwane University of Technology175 Mandela RoadPretoria0001South Africa

The occurrence,distribution and ecological risk assessment of twelve(12)organophosphorus flame retardants(oPFRs)were investigated in sediments from the Vaal River,South *** halogenated oPFRs[tris-(2-chloroethyl)phosphate(TCEP),three isomers of tris-(chloropropyl)phosphate(TCiPPs),tris-(1,3-dichloro-2-propyl)phosphate(TDCiPP)and tris-(2,3 dibromopropyl)phosphate(TDBPP)]and six non-halogenated oPFRs[tris-(n-butyl)phosphate(TBP),tris-(phenyl)phosphate(TPhP),tris-(butyl ethoxy)phosphate(TBoEP),tris-(2-ethylhexyl)phosphate(TEHP),diphenyl-2-ethylhexyl phosphate(DPEHP)and tris-(m-cresyl)phosphate(m-TCP)]were detected in this *** concentrations of twelve oPFRs in total(S12oPFRs)ranged from 68 to 278 ng g^-1 dry weight(dw)with the mean and median of 138 and 120 ng g^-1;*** non-halogenated oPFRs showed more abundances than the halogenated oPFRs with TDBPP,TBP,and TBoEP the most abundant ***,concentrations of oPFRs in more urbanized region were higher than those in less urbanized *** the concentrations of oPFRs and total organic carbon(ToC)were correlated,a moderate and significant correlation(pour results showed that m-TCP poses high risk(HQ>1)while TBoEP,TPhP,and TBP posed medium risk(0.1osing negligible risk(HQobtained in this study provides valuable information on the occurrence and risks of the investigated oPFRs within Vaal River.

关键词： oPFRs Concentrations Risk assessment Sediments Vaal river

Determination of mercury and its fractionation products in samples from legacy use of mercury amalgam in gold processing in Randfontein,South Africa

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Emerging Contaminants 2016年第3期2卷 157-165页

作者： Tshia Malehase Adegbenro P.Daso jonathan o.okonkwo Department of Environmental Water and Earth SciencesTshwane University of TechnologyPrivate Bag X680175 Nelson Mandela DriveArcadiaPretoria0001South Africa

This study aimed at determining the levels of total mercury(THg)in tailings dams,soil,sediments and water samples collected in the vicinity of legacy mercury amalgam gold *** digestion was employed in sample digestion followed by analysis using *** dams,community and garden soil,and stream sediments were further investigated for mercury fractions using a five step sequential extraction *** concentrations of THg in tailings dams,community and gardens soil were 0.890e6.755 mg/g,0.431e0.968 mg/g and 0.471e1.019 mg/g,respectively and the concentrations of THg in the sediments obtained from tailings dams,streams and wetlands were 0.649e1.998 mg/g,0.604 e1.356 mg/g and 0.681e1.356 mg/g,*** concentrations of THg,in aqueous samples obtained from tailings,streams and wetlands were 0.032e0.070 mg/l,0.004e0.068 mg/l and 0.007e0.012 mg/l,*** sequential extraction procedure showed that most Hg in the tailings dams was largely elemental Hg and Hg bound to *** and sediments were largely dominated by organic bound *** seasonal correlation was observed in tailings dams soil,but weak seasonal correlation in soils collected in the vicinity of ***,a strong seasonal correlationwas observed in sediments and water *** concentrations of Hg obtained largely existed in organic and sulphate bound Hg and there is elevated potential to methylate Hg.

关键词： Mercury concentrations Fractions Gold mining Legacy amalgam Tailing dams Soil Sediment Water Speciation

occurrence and distribution of tetrabromobisphenol A and its derivative in river sediments from Vaal River Catchment,South Africa

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Emerging Contaminants 2017年第3期3卷 121-126页

作者： Tlou B.Chokwe jonathan o.okonkwo Mutshinyalo S.Nwamadi Rand Water Scientific Services 2 Barrage RoadVereeniging1930 South Africa Department of Water Environmental and Earth SciencesTshwane University of Technology175 Mandela RoadPretoria0001 South Africa Spectra Analytical Facility University of JohannesburgKingsway RoadAuckland ParkJohannesburg2006 South Africa

Brominated flame retardants(BFRs)compounds have been widely added in a number of products to reduce their *** the present study,the concentrations and distribution of tetrabromobisphenol A(TBBPA)and its derivatives,*** dibromopropyl ether(TBPDBPE),tetrabromobisphenol A bis-dibromopropyl ether(TBBPA BDBPE),tetrabromobisphenol A bis-allyl ether(TBBPA BAE)were investigated in sediment samples collected from the Vaal River catchment,South *** results showed that all these pollutants were detected in sediments with TBBPA BAE being the most abundant *** TBBPA BAE concentrations ranged from 3.5 to 44.4 ng/g(mean 16 ng/g)while the concentration ranged from not detected(nd)to 2.4 ng/g(mean 0.6 ng/g),nd-21.0 ng/g(mean 6 ng/g)and nd-2.0 ng/g(mean 0.2 ng/g)for TBPDBPE,TBBPA and TBBPA BDBPE;*** concentrations of these pollutants were found in sampling sites receiving effluents of wastewater treatment works(WWTWs)treating some industrial wastewater suggesting effluents might play an important role in the contamination of BFRs in the *** correlation between TBBPA and TBBPA BAE was observed implying different sources or environmental fates between these ***,the results showed a need for further studies to be undertaken in investigating the presence,fate and sources of alternative halogenated flame retardants in the environment.

关键词： Brominated flame retardants Tetrabromobisphenol A derivatives Concentrations Sediments Vaal river

occurrence and environmental levels of triclosan and triclocarban in selected wastewater treatment plants in Gauteng Province,South Africa

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Emerging Contaminants 2017年第3期3卷 107-114页

作者： Raisibe F.Lehutso Adegbenro P.Daso jonathan o.okonkwo Department of Environmental Water&Earth SciencesFaculty of ScienceTshwane University of Technology175 Nelson Mandela DrivePrivate Bag X680ArcadiaPretoria 0001South Africa

Triclosan and triclocarban are industrial chemicals that are frequently added into consumer and personal care *** on the levels on these compounds in water systems in the African continent is still very *** the present study,the occurrence,seasonal variation,and estimated removal of TCS and TCC in six different wastewater treatment plants in Gauteng Province,South Africa,were investigated over a period of two years,together with effluent receiving river *** instrumental analysis was carried out using Shimadzu LCMS/MS 8030,employing negative electrospray *** target compounds were ubiquitously detected with influent and raw sludge having elevated ***,TCS concentrations were higher than those of *** concentrations obtained for TCS were(influent,2.01e17.6 mg/L;effluent,0.990e13.0 mg/L;river,0.880e8.72 mg/L;raw sludge,3.65e15.0 mg/kg;treated sludge,2.08e7.81 mg/kg and biosolids,2.16e13.5 mg/kg);while TCC levels were obtained to be(influent,0.0860e2.84 mg/L;effluent,oD-1.89 mg/L;river,nd-0.360 mg/L;raw sludge,3.65e11.8 mg/kg;treated sludge,1.21e9.19 mg/kg;biosolids,2.59e8.23 mg/kg).occurrence of TCS in wastewater was found to be influenced by temporal *** was not the case for occurrence of TCS and TCC in sludge *** to their environmental occurrence,the estimated treatment efficiencies also varied across the wastewater treatments plants,with the highest elimination rates of 63%and 97%for TCS and TCC,respectively.

关键词： Triclosan Triclocarban LC-MS/MS Seasonal concentrations Wastewater Sludge South Africa

Poly-and perfluoroalkyl substances(PFASs)in sediment samples from Roodeplaat and Hartbeespoort Dams,South Africa

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Emerging Contaminants 2020年第1期6卷 367-375页

作者： Bulelwa Batayi jonathan o.okonkwo Peter A.Daso Cornelius C.Rimayi Department of Environmental Water and Earth SciencesFaculty of ScienceTshwane University of TechnologyArcadia CampusPretoria0001South Africa Department of Water and Sanitation Resource Quality Information Services(RQIS)RoodeplaatP.Bag X3130001PretoriaSouth Africa

This study aimed at determining PFAS concentrations in sediments obtained from two important water systems in South Africa,namely,the Roodeplaat and Hartbeespoort *** samples were collected in March and June representing summer and winter *** analytes were extracted using the half-dry alkaline method followed by solid phase extraction and analysed with liquid chromatography-tandem mass *** mean PFASs concentrations in Roodeplaat Dam(0.14 e89.04 ng g^-1)were significantly higher(p=0.016)than in Hartbeespoort Dam(0.03e31.37 ng g^-1).Perfluoro-n-decane sulfonic acid(PFDS),perfluoro-n-heptyl sulfonate(PFHpS),perfluoro-n-nonane sulfonic acid(PFNS)and perfluoro-n-octane sulfonic acid(PFoS)were the most dominant PFASs *** were observed to be generally higher in summer compared to winter,however,the difference is statistically insignificant(p=0.659).The perfluorosulfonic acids(PFSAs)was more dominant than the perfluorocarboxylic compounds,suggesting possible preferential usage of PFSAs in this *** findings were different from reports from China and Korea,which reported long chain perfluorinated carboxylic acids(PFCAs)in sediments as the dominant *** results also revealed that the PFAS concentrations found in the present study were higher than the concentrations found in China,Germany,and Ethiopia but lower than the concentrations detected in the Western Cape Province in South Africa.

关键词： PFASs Concentrations Sediments Hartbeespoort and roodeplaat dams South Africa

Alkylphenols and alkylphenol ethoxylates in dust from homes, offices and computer laboratories: Implication for personal exposure via inadvertent dust ingestion

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Emerging Contaminants 2017年第4期3卷 127-131页

作者： ovokeroye A.Abafe Tlou B.Chokwe jonathan o.okonkwo Bice S.Martincigh Agricultural Research Council-oVR 100 Old Soutpan RoadOnderstepoortPretoria0110South Africa Rand Water Scientific Services 2 Barrage RoadVereeniging1930South Africa Department of Water Environmental and Earth SciencesTshwane University of Technology175 Mandela RoadPretoria0001South Africa School of Chemistry and Physics University of KwaZulu-NatalPrivate Bag X54001Durban4000South Africa

In the present study,the levels of alkylphenols(APs)and alkylphenol ethoxylates(APEs)in indoor dust of three different microenvironments were measured and daily intake via dust ingestion *** and alkylphenol ethoxylates were extracted with the aid of sonication and analyzed by gas chromatography mass spectrometry after heptafluorobutyric anhydride *** concentration values of these pollutants ranged from 1918e10935 ng g1;343e12438 ng g1 and 1122 e15324 ng g1 in dust samples from homes,computer laboratories and offices,*** all the microenvironment studied,di-NPE and mono-NPE were the most abundant isomers suggesting widespread use of NPE-based consumer products in the studied *** daily exposure dose(DED)was estimated using min,mean and max concentrations of APs and APEs detected in respected *** worst case scenario for the exposure of APEs was highest for toddlers at 146 ng kg1 bw day1 followed by teenagers at 11.3 ng kg1 bw day1 and adults at daily exposure of 8.53 ng kg1 bw day*** the daily exposure doses are low,there is a cause for concern as these surfactants are not regulated in many developing countries and their use may be increasing.

关键词： Alkylphenols Alkylphenol ethoxylates Concentrations Indoor dust Exposure assessment

Distribution of total mercury in surface sediments and African catfish(Clarias gariepinus)from Akaki River catchment and Aba Samuel Reservoir,downstream to the mega-city Addis Ababa,Ethiopia

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Emerging Contaminants 2018年第1期4卷 32-39页

作者： Alemnew Berhanu Kassegne jonathan o.okonkwo Tarekegn Berhanu Esho Kebede Nigussie Mekonnen Tshia Malehase Seyoum Leta Asfaw Center for Environmental Science Addis Ababa UniversityP.O.Box 1176Addis AbabaEthiopia Department of Chemistry Debre Berhan UniversityP.O.Box 445Debre BerhanEthiopia Department of Environmental Water&Earth SciencesTshwane University of Technology175 Nelson Mandela DrivePrivate Bag X680ArcadiaPretoriaSouth Africa Central Research Laboratory Addis Ababa Science and Technology UniversityP.O.Box 16417AddisAbabaEthiopia Department of Chemistry Tshwane University of TechnologyP.O.Box 56208Arcadia0007South Africa Department of Chemistry College of Natural and Computational SciencesMekelle UniversityP.O.Box 231MekelleEthiopia

Total mercury(THg)levels were determined in sediment(n=22)and muscle of Clarias gariepinus(n=36)in dry and rainy seasons from Akaki River catchment and Aba Samuel Reservoir,Ethiopia in *** analyses of THg were performed using cold vapor-atomic absorption spectrometer(CV-AAS)after acid digestion *** relationship of THg levels to size of the fish has also been *** THg levels in sediments range from 9.5e43.8 mg/kg dry wt in the dry and 20.6e175.4 mg/kg dry wt in the rainy *** study indicated that the levels of THg in sediments varies spatially and *** both seasons,THg levels increased from upstream to downstream areas,revealing increased anthropogenic inputs of mercury *** was also found that the THg concentrations in all the sediment samples were below the US EPA guideline value of 200 mg/kg dry *** THg levels in Clarias gariepinus were in the range from 360e924 mg/kg dry wt in the dry and 325e1233 mg/kg dry wt in the rainy seasons,and had positive relationship to the total length and body *** THg concentrations found in Clarias gariepinus were within the acceptable guidelines of the FAo/***,the muscle of Clarias gariepinus from the study area is not hazardous to human health with respect to ***,the average value of THg seems to be slightly higher than results reported from other Ethiopian freshwater ***,monitoring of mercury species in sediment and different organs of fish are strongly recommended.

关键词： pollution. mercury upstream

A review of sources,fate,levels,toxicity,exposure and transformations of organophosphorus flame-retardants and plasticizers in the environment

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Emerging Contaminants 2020年第1期6卷 345-366页

作者： Tlou B.Chokwe ovokeroye A.Abafe Senzy P.Mbelu jonathan o.okonkwo Linda L.Sibali Scientific Services Unit Capricorn District Municipality24 Thabo Mbeki StreetPolokwane0699South Africa Department of Environmental Sciences University of South AfricaChristaan de Wet RoadFlorida1709South Africa onderstepoort Veterinary Research Agricultural Research Council100 Old Soutpan RoadOnderstepoortPretoria0110South Africa Scientific Services Rand Water2 Barrage RoadVereeniging1930South Africa Department of Water Environmental and Earth SciencesTshwane University of Technology75 Mandela DrivePretoria0001South Africa

organophosphate esters(oPEs)are esters of phosphoric acid that are increasingly used as plasticizers and by the flame-retardants industries as replacement for the regulated polybrominated diphenyl *** most commonly classes of these pollutants are the chlorinated-and *** extent and magnitude of oPEs occurrence in the environment,combined with striking structural similarities to toxic organophosphorus pesticides has led to public concern over risk posed by these *** peer-reviewed literature published from the last decade(2010e2019),concentrations and distributions of commonly studied oPEs based on their occurrence in different matrices around the globe were evaluated and *** pollutants have a wide range of physicochemical properties such as their water solubility’s,logKow value,vapour pressure and bioconcentration factors(BCFs)which are very important factors in assessing their behaviour in different environmental *** progress in research on oPEs over the years,full understanding of the environmental behaviour and fate of these pollutants are still *** by which these pollutants enter the environment in conjunction with their concentrations together with their toxicities,estimated daily intakes,transformation products and fates are *** is envisaged that this review will heighten the importance of identifying emerging issues,data gaps and provide a future research agenda for oPEs.

关键词： organophosphorus compounds Concentrations Sources Fate Toxicity Estimated daily intakes

Ecological risk assessment of organochlorine pesticides and polychlorinated biphenyls in water and surface sediment samples from Akaki River catchment,central Ethiopia

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Emerging Contaminants 2020年第1期6卷 396-404页

作者： Alemnew Berhanu Kassegne jonathan o.okonkwo Tarekegn Berhanu Adegbenro P.Daso olubiyi I.olukunle Seyoum Leta Asfaw Department of Chemistry Debre Berhan UniversityP.O.Box 455Debre BerhanEthiopia Center for Environmental Science Addis Ababa UniversityP.O.Box 1176Addis AbabaEthiopia Department of Environmental Water&Earth SciencesTshwane University of Technology175 Nelson Mandela DrivePrivate Bag X680ArcadiaPretoriaSouth Africa Central Research Laboratory Addis Ababa Science and Technology UniversityP.O.Box 16417Addis AbabaEthiopia School of Public and Environmental Affairs Indiana UniversityBloomingtonIN47405USA

The current status of persistent organic pollutants in Ethiopian environment is not well monitored despite the existing pollution potential from a number of *** and sediment samples collected from Akaki River catchment and Aba Samuel Reservoir,Central Ethiopia were analyzed to assess the concentrations,distribution,possible sources and potential ecological risk of eight organochlorine pesticides(oCPs)and seven polychlorinated biphenyls(PCBs).Water and sediment samples were extracted by liquid-liquid and Soxhlet extraction respectively,and analyzed using gas chromatography-mass spectroscopy(GC-MS).The detectable oCPs and PCBs in water samples were DDT,DDE,DDD,lindane and dieldrin and PCB-28,PCB-101 and PCB-118,respectively in the rainy *** sediment samples showed the presence of lindane in the dry and p,p’-DDT,p,p’-DDE,p,p’-DDD,a,b-endosulfan,heptachlor epoxide(B),and dieldrin in the rainy *** the indicator PCBs analyzed,sediment samples showed the presence of PCB-52,PCB-101 and PCB-118 in the dry and all indicator PCBs in the rainy *** analysis showed that PCBs and detected oCPs were mainly from the historical input of commercial products,but there were recent discharge of DDT and lindane into the river *** risk assessment of the analyzed oCPs and PCBs using water and sediment quality guidelines indicated that lindane in the dry and p’-DDT,p,p’-DDE,p,p’-DDD,heptachlore epoxide and dieldrin in the rainy seasons in the sediment samples from Akaki river and Aba Samuel reservoir were above the limit at most of the *** suggests there is greater possibility of higher ecological hazards in these ***,the levels of total PCB concentrations and other oCPs at all sites were below the limit and thus their potential ecotoxicological risks were rather low.

关键词： Akaki river organochlorine pesticides Polychlorinated biphenyls Sediment Water

A Simplified Analytical Procedure for Simultaneous Determination of Alkylphenol Ethoxylates and Brominated Flame Retardants in Fish Tissue Samples from Vaal River,South Africa

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American Journal of Analytical Chemistry 2015年第5期6卷 422-428页

作者： Tlou B.Chokwe jonathan o.okonkwo Linda L.Sibali Elmari Kruger Hein du Preez Reveck Hariram Esper J.Ncube Scientific Services Rand WaterVereenigingSouth Africa Department of Environmental Water and Earth SciencesTshwane University of TechnologyPretoriaSouth Africa Directorate of Research and Innovation Tshwane University of TechnologyPretoriaSouth Africa

In this study, the concentration of alkylphenol ethoxylates (APEs) and brominated flame retardants (BFRs) were determined in fish samples, Labeo umbratus and Carp, collected from the Vaal River in South Africa. Ultrasonic-assisted extraction technique was used to extract the organic contaminants from fish samples, and the resulting extract was purified by sulphuric acid lipid removal followed by Strata X-cartridge SPE clean-up. The APEs and BFRs were derivatized using heptafluorobutyric anhydride before analysis with GC-MS. In both types of fish samples, lower oligomers of APEs were more abundant than the higher oligomers, while HBCD, BDE99 and PBB101 were the dominant BFRs. The concentrations of these pollutants ranged from 1.061 ng/g lipids (t-BP) in Labeo umbratus to 11.860 ng/g lipids (HBCD) in Carp.

关键词： Alkylphenol Ethoxylates Brominated Flame Retardants Fish Sample Heptafluorobutyric Anhydride Derivatization Vaal River South Africa