We welcome the opportunity to address comments provided by Dr.Noubactep and to further emphasize the concepts developed in our article titled“Long–term performance evaluation of zero-valent iron amended permeable re...We welcome the opportunity to address comments provided by Dr.Noubactep and to further emphasize the concepts developed in our article titled“Long–term performance evaluation of zero-valent iron amended permeable reactive barriers for groundwater remediation–A mechanistic approach”(Lawrinenko et al.,2023).展开更多
In the first phase of this study, the effectiveness of intrinsic bioremediation on the containment of petroleum hydrocarbons was evaluated at a gasoline spill site. Evidences of the occurrence of intrinsic bioremediat...In the first phase of this study, the effectiveness of intrinsic bioremediation on the containment of petroleum hydrocarbons was evaluated at a gasoline spill site. Evidences of the occurrence of intrinsic bioremediation within the BTEX （benzene, toluene, ethylbenzene, and xylenes） plume included （1） decreased BTEX concentrations; （2） depletion of dissolved oxygen （DO）, nitrate, and sulfate; （3） production of dissolved ferrous iron, methane, and CO2; （4） deceased pH and redox potential; and （5） increased methanogens, total heterotrophs, and total anaerobes, especially within the highly contaminated areas. In the second phase of this study, enhanced aerobic bioremediation process was applied at site to enhance the BTEX decay rates. Air was injected into the subsurface near the mid-plume area to biostimulate the naturally occurring microorganisms for BTEX biodegradation. Field results showed that enhanced bioremediation process caused the change of BTEX removal mechanisms from anaerobic biodegradation inside the plume to aerobic biodegradation. This variation could be confirmed by the following field observations inside the plume due to the enhanced aerobic bioremediation process： （1） increased in DO, CO2, redox potential, nitrate, and sulfate, （2） decreased in dissolved ferrous iron, sulfide, and methane, （3） increased total heterotrophs and decreased total anaerobes. Field results also showed that the percentage of total BTEX removal increased from 92% to 99%, and the calculated total BTEX first-order natural attenuation rates increased from 0.0092% to 0.0188% per day, respectively, after the application of enhanced bioremediation system from the spill area to the downgradient area （located approximately 300 m from the source area）.展开更多
Permeable reactive barriers(PRBs)are used for groundwater remediation at contaminated sites worldwide.This technology has been efficient at appropriate sites for treating organic and inorganic contaminants using zero-...Permeable reactive barriers(PRBs)are used for groundwater remediation at contaminated sites worldwide.This technology has been efficient at appropriate sites for treating organic and inorganic contaminants using zero-valent iron(ZVI)as a reductant and as a reactive material.Continued development of the technology over the years suggests that a robust understanding of PRB performance and the mechanisms involved is still lacking.Conflicting information in the scientific literature downplays the critical role of ZVI corrosion in the remediation of various organic and inorganic pollutants.Additionally,there is a lack of information on how different mechanisms act in tandem to affect ZVI-groundwater systems through time.In this review paper,we describe the underlying mechanisms of PRB performance and remove isolated misconceptions.We discuss the primary mechanisms of ZVI transformation and aging in PRBs and the role of iron corrosion products.We review numerous sites to reinforce our understanding of the interactions between groundwater contaminants and ZVI and the authigenic minerals that form within PRBs.Our findings show that ZVI corrosion products and mineral precipitates play critical roles in the long-term performance of PRBs by influencing the reactivity of ZVI.Pore occlusion by mineral precipitates occurs at the influent side of PRBs and is enhanced by dissolved oxygen and groundwater rich in dissolved solids and high alkalinity,which negatively impacts hydraulic conductivity,allowing contaminants to potentially bypass the treatment zone.Further development of site characterization tools and models is needed to support effective PRB designs for groundwater remediation.展开更多
Nanomaterials are applicable in the areas of reduction of environmental burden,reduction/treatment of industrial and agricultural wastes,and nonpoint source(NPS)pollution control.First,environmental burden reduction i...Nanomaterials are applicable in the areas of reduction of environmental burden,reduction/treatment of industrial and agricultural wastes,and nonpoint source(NPS)pollution control.First,environmental burden reduction involves green process and engineering,emissions control,desulfurization/denitrification of nonrenewable energy sources,and improvement of agriculture and food systems.Second,reduction/treatment of industrial and agricultural wastes involves converting wastes into products,groundwater remediation,adsorption,delaying photocatalysis,and nanomembranes.Third,NPS pollution control involves controlling water pollution.Nanomaterials alter physical properties on a nanoscale due to their high specific surface area to volume ratio.They are used as catalysts,adsorbents,membranes,and additives to increase activity and capability due to their high specific surface areas and nano-sized effects.Thus,nanomaterials are more effective at treating environmental wastes because they reduce the amount of material needed.展开更多
Many drinking water treatment plants in the U.S. have switched from chlorination to chloramination to lower levels of regulated trihalomethane(THM) and haloacetic acid(HAA) disinfection byproducts(DBPs) in drinking wa...Many drinking water treatment plants in the U.S. have switched from chlorination to chloramination to lower levels of regulated trihalomethane(THM) and haloacetic acid(HAA) disinfection byproducts(DBPs) in drinking water and meet the current regulations. However, chloramination can also produce other highly toxic/carcinogenic, unregulated DBPs: iodoacids, iodo-THMs, and N-nitrosodimethylamine(NDMA). In practice, chloramines are generated by the addition of chlorine with ammonia, and plants use varying amounts of free chlorine contact time prior to ammonia addition to effectively kill pathogens and meet DBP regulations. However, iodo-DBPs and nitrosamines are generally not considered in this balancing of free chlorine contact time. The goal of our work was to determine whether an optimal free chlorine contact time could be established in which iodo-DBPs and NDMA could be minimized, while keeping regulated THMs and HAAs below their regulatory limits. The effect of free chlorine contact time was evaluated for the formation of six iodo-trihalomethanes(iodo-THMs), six iodo-acids, and NDMA during the chloramination of drinking water. Ten different free chlorine contact times were examined for two source waters with different dissolved organic carbon(DOC) and bromide/iodide. For the low DOC water at pH 7 and 8, an optimized free chlorine contact time of up to 1 h could control regulated THMs and HAAs, as well as iodo-DBPs and NDMA. For the high DOC water, a free chlorine contact time of 5 min could control iodo-DBPs and NDMA at both p Hs, but the regulated DBPs could exceed the regulations at pH 7.展开更多
Copper-based pesticides and wood preservatives could end up in the environment during production,use,and end-of-life via different pathways that could cause unintended ecolog-ical and adverse health effects.This paper...Copper-based pesticides and wood preservatives could end up in the environment during production,use,and end-of-life via different pathways that could cause unintended ecolog-ical and adverse health effects.This paper provides the effect of colloid-size Cu-based pesti-cides(CuPRO and Kocide),micronized Cu azole(MCA-1 and MCA-2)and alkaline Cu quater-nary(ACQ)treated woods,Cu^(2+),Cu^(2+) spiked untreated wood(UTW),and CuCO_(3) solutions against Gram-positive Bacillus species using five-day biochemical oxygen demand(BOD 5)stan-dard test.The total Cu leached from MCA-1,MCA-2,and ACQ in Milli-Q water after 5 days were -0.1,-0.11,and -0.64 g/kg of wood,respectively.However,the form of Cu leached from MCA woods was mostly ionic(>90%).The total organic carbon(TOC)content of any tested wood(UTW/MCA-1/MCA-2/ACQ)was -99%of its corresponding total carbon(TC)content,whereas the TOC of any tested wood sawdust exceeded that of its corresponding piece/block by>300%.The dissolved oxygen(DO)consumption value in the presence of Cu^(2+),CuCO_(3),CuPRO,and Kocide solutions was significantly influenced by Cu particles/ions.However,the DO consumption value in the presence of UTW/MCA-1/MCA-2/ACQ woods was significantly influenced by organics leached from woods.On the other hand,the DO consumption of MCA sawdust was greater than(300%)that of MCA pieces/block.The findings of this study provide more insight into how organics leached from woods significantly reduce the toxic effects of Cu ions against Gram-positive Bacillus species.展开更多
Background:Perfluorooctanoic acid(PFOA)is an environmental contaminant associated with adverse metabolic outcomes in developmentally exposed human populations and mouse models.Hexafluoropropylene oxide-dimer acid(HFPO...Background:Perfluorooctanoic acid(PFOA)is an environmental contaminant associated with adverse metabolic outcomes in developmentally exposed human populations and mouse models.Hexafluoropropylene oxide-dimer acid(HFPO-DA,commonly called GenX)has replaced PFOA in many industrial applications in the U.S.and Europe and has been measured in global water systems from<1 to 9350 ng/L HFPO-DA.Health effects data for GenX are lacking.Objective:Determine the effects of gestational exposure to GenX on offspring weight gain trajectory,adult metabolic health,liver pathology and key adipose gene pathways in male and female CD-1 mice.Methods:Daily oral doses of GenX(0.2,1.0,2.0 mg/kg),PFOA(0.1,1.0 mg/kg),or vehicle control were administered to pregnant mice(gestation days 1.5-17.5).Offspring were fed a high-or low-fat diet(HFD or LFD)at weaning until necropsy at 6 or 18 weeks,and metabolic endpoints were measured over time.PFOA and GenX serum and urine concentrations,weight gain,serum lipid parameters,body mass composition,glucose tolerance,white adipose tissue gene expression,and liver histopathology were evaluated.Results:Prenatal exposure to GenX led to its accumulation in the serum and urine of 5-day old pups(P=0.007,P<0.001),which was undetectable by weaning.By 18 weeks of age,male mice fed LFD in the 2.0 mg/kg GenX group displayed increased weight gain(P<0.05),fat mass(P=0.016),hepatocellular microvesicular fatty change(P=0.015),and insulin sensitivity(P=0.014)in comparison to control males fed LFD.Female mice fed HFD had a significant increase in hepatocyte single cell necrosis in 1.0 mg/kg GenX group(P=0.022)and 1.0 mg/kg PFOA group(P=0.003)compared to control HFD females.Both sexes were affected by gestational GenX exposure;however,the observed phenotype varied between sex with males displaying more characteristics of metabolic disease and females exhibiting liver damage in response to the gestational exposure.Conclusions:Prenatal exposure to 1 mg/kg GenX and 1 mg/kg PFOA induces adverse metabolic outcomes in adult mic展开更多
Short-term tests for mutagenicity(also referred to as short-term tests for genetic toxicity)have been used extensively toidentify mutagens and potential carcinogens.Increasingly,the sameshort-term tests are being used...Short-term tests for mutagenicity(also referred to as short-term tests for genetic toxicity)have been used extensively toidentify mutagens and potential carcinogens.Increasingly,the sameshort-term tests are being used to identify antimutagens andpotential anticarcinogens.The data on antimutagenicity are comolexin part because of three simultaneous experimental variables:themutagens(and/or spontaneous mutation)studied,the antimutagensstudied,and the short-term tests used.In order to summarize anddisplay these complex published data on antimutagenicity,wedeveloped the concept of 'activity profiles for antimutagens'('antimutagenicity profiles')(Waters et al.1990,Brockman et al.1992).An antimutagenicity profile is composed of two parallel setsof bargraphs.For each combination of antimitagen,mutagen,andshort-term test displayed,the upper graph displays the mutagenconcentrations tested,whereas the lower graph displays the result asmaximum percent inhibition,maximum percent enhancement,or noeffect.The展开更多
Hydrogen peroxide (H2O2 ) concentrations were measured at two sites. One was on Lushan Mountain in May, 1987. The other was in Beijing in August, 1987 and in December, 1986. The automated fluorometric method was used... Hydrogen peroxide (H2O2 ) concentrations were measured at two sites. One was on Lushan Mountain in May, 1987. The other was in Beijing in August, 1987 and in December, 1986. The automated fluorometric method was used for the determination of H2O2 . The concentrations of H2O2 ranged from approximately 0.50 to 4.32 ppb on Lushan Mountain. The concentrations of H2O2 ranged from approximately 0.05 to 1.49 ppb in August in Beijing, and it was only 0.01 ppb in December in Beijing.展开更多
Low levels (ng/g) of musk ketone (MK),used as a fragrance additive in the formulation of personal care products,are frequently detected in the water and other environment.Thus,aquatic organisms can be continuously exp...Low levels (ng/g) of musk ketone (MK),used as a fragrance additive in the formulation of personal care products,are frequently detected in the water and other environment.Thus,aquatic organisms can be continuously exposed to MK.In this study,kinetics and dose-response assessments of 2-amino-MK (AMK) metabolite,bound to cysteine-hemoglobin (Hb) in rainbow trout,formed by enzymatic nitro-reduction of MK have been demonstrated.Trout were exposed to a single exposure of 0.010,0.030,0.10,and 0.30 mg MK/g fish.Tw...展开更多
In this study,a new analytical technique was developed for the identification and quantification of multifunctional compounds containing simultaneously at least one hydroxyl or one carboxylic group,or both.This techni...In this study,a new analytical technique was developed for the identification and quantification of multifunctional compounds containing simultaneously at least one hydroxyl or one carboxylic group,or both.This technique is based on derivatizing first the carboxylic group(s) of the multifunctional compound using an alcohol (e.g.,methanol,1-butanol) in the presence of a relatively strong Lewisacid (BF3) as a catalyst.This esterification reaction quickly and quantitatively converts carboxylic acids to their ester forms.The second step is based on silylation of the ester compounds using bis(trimethylsilyl) trifluoroacetamide (BSTFA) as the derivatizing agent.For compounds bearing ketone groups in addition to carboxylic and hydroxyl groups,a third step was used based on PFBHA derivatizationof the carbonyls.Different parameters including temperature,reaction time,and effect due to artifacts were optimized.A GC/MS in EI and in methane-CI mode was used for the analysis of these compounds.The new approach was tested on a number of multifunctional compounds.The interpretation of their EI (70 eV) and CI mass spectra shows that critical information is gained leading to unambiguous identification of unknown compounds.For example,when derivatized only with BF3-methanol,their mass spectra comprise primary ions at m/z M ·+ +1,M ·+ +29,and M ·+ - 31 for compounds bearing only carboxylic groups and M ·+ +1,M ·+ +29,M ·+ -31,and M ·+ -17 for those bearing hydroxyl andcarboxylic groups.However,when a second derivatization (BSTFA) was used,compounds bearing hydroxyl and carboxylic groups simultaneously show,in addition to the ions observed before,ions at m/z M ·+ +73,M ·+ -15,M ·+ -59,M ·+ -75,M ·+ -89,and 73.To the best of our knowledge,this technique describes systematically for the first time a method for identifying multifunctional oxygenated compounds containing simultaneously one or more hydroxyl and carboxylic acid groups.展开更多
The short-term tests (STT) that have been usedsuccessfully to identify mutagens and potentialcarcinogens increasingly are being used to identifyantimutagens and potential anticarcinogens.Theconcept of activity profile...The short-term tests (STT) that have been usedsuccessfully to identify mutagens and potentialcarcinogens increasingly are being used to identifyantimutagens and potential anticarcinogens.Theconcept of activity profiles,already appliedsuccessfully to the display of mutagenicity展开更多
文摘We welcome the opportunity to address comments provided by Dr.Noubactep and to further emphasize the concepts developed in our article titled“Long–term performance evaluation of zero-valent iron amended permeable reactive barriers for groundwater remediation–A mechanistic approach”(Lawrinenko et al.,2023).
文摘In the first phase of this study, the effectiveness of intrinsic bioremediation on the containment of petroleum hydrocarbons was evaluated at a gasoline spill site. Evidences of the occurrence of intrinsic bioremediation within the BTEX （benzene, toluene, ethylbenzene, and xylenes） plume included （1） decreased BTEX concentrations; （2） depletion of dissolved oxygen （DO）, nitrate, and sulfate; （3） production of dissolved ferrous iron, methane, and CO2; （4） deceased pH and redox potential; and （5） increased methanogens, total heterotrophs, and total anaerobes, especially within the highly contaminated areas. In the second phase of this study, enhanced aerobic bioremediation process was applied at site to enhance the BTEX decay rates. Air was injected into the subsurface near the mid-plume area to biostimulate the naturally occurring microorganisms for BTEX biodegradation. Field results showed that enhanced bioremediation process caused the change of BTEX removal mechanisms from anaerobic biodegradation inside the plume to aerobic biodegradation. This variation could be confirmed by the following field observations inside the plume due to the enhanced aerobic bioremediation process： （1） increased in DO, CO2, redox potential, nitrate, and sulfate, （2） decreased in dissolved ferrous iron, sulfide, and methane, （3） increased total heterotrophs and decreased total anaerobes. Field results also showed that the percentage of total BTEX removal increased from 92% to 99%, and the calculated total BTEX first-order natural attenuation rates increased from 0.0092% to 0.0188% per day, respectively, after the application of enhanced bioremediation system from the spill area to the downgradient area （located approximately 300 m from the source area）.
文摘Permeable reactive barriers(PRBs)are used for groundwater remediation at contaminated sites worldwide.This technology has been efficient at appropriate sites for treating organic and inorganic contaminants using zero-valent iron(ZVI)as a reductant and as a reactive material.Continued development of the technology over the years suggests that a robust understanding of PRB performance and the mechanisms involved is still lacking.Conflicting information in the scientific literature downplays the critical role of ZVI corrosion in the remediation of various organic and inorganic pollutants.Additionally,there is a lack of information on how different mechanisms act in tandem to affect ZVI-groundwater systems through time.In this review paper,we describe the underlying mechanisms of PRB performance and remove isolated misconceptions.We discuss the primary mechanisms of ZVI transformation and aging in PRBs and the role of iron corrosion products.We review numerous sites to reinforce our understanding of the interactions between groundwater contaminants and ZVI and the authigenic minerals that form within PRBs.Our findings show that ZVI corrosion products and mineral precipitates play critical roles in the long-term performance of PRBs by influencing the reactivity of ZVI.Pore occlusion by mineral precipitates occurs at the influent side of PRBs and is enhanced by dissolved oxygen and groundwater rich in dissolved solids and high alkalinity,which negatively impacts hydraulic conductivity,allowing contaminants to potentially bypass the treatment zone.Further development of site characterization tools and models is needed to support effective PRB designs for groundwater remediation.
文摘Nanomaterials are applicable in the areas of reduction of environmental burden,reduction/treatment of industrial and agricultural wastes,and nonpoint source(NPS)pollution control.First,environmental burden reduction involves green process and engineering,emissions control,desulfurization/denitrification of nonrenewable energy sources,and improvement of agriculture and food systems.Second,reduction/treatment of industrial and agricultural wastes involves converting wastes into products,groundwater remediation,adsorption,delaying photocatalysis,and nanomembranes.Third,NPS pollution control involves controlling water pollution.Nanomaterials alter physical properties on a nanoscale due to their high specific surface area to volume ratio.They are used as catalysts,adsorbents,membranes,and additives to increase activity and capability due to their high specific surface areas and nano-sized effects.Thus,nanomaterials are more effective at treating environmental wastes because they reduce the amount of material needed.
文摘Many drinking water treatment plants in the U.S. have switched from chlorination to chloramination to lower levels of regulated trihalomethane(THM) and haloacetic acid(HAA) disinfection byproducts(DBPs) in drinking water and meet the current regulations. However, chloramination can also produce other highly toxic/carcinogenic, unregulated DBPs: iodoacids, iodo-THMs, and N-nitrosodimethylamine(NDMA). In practice, chloramines are generated by the addition of chlorine with ammonia, and plants use varying amounts of free chlorine contact time prior to ammonia addition to effectively kill pathogens and meet DBP regulations. However, iodo-DBPs and nitrosamines are generally not considered in this balancing of free chlorine contact time. The goal of our work was to determine whether an optimal free chlorine contact time could be established in which iodo-DBPs and NDMA could be minimized, while keeping regulated THMs and HAAs below their regulatory limits. The effect of free chlorine contact time was evaluated for the formation of six iodo-trihalomethanes(iodo-THMs), six iodo-acids, and NDMA during the chloramination of drinking water. Ten different free chlorine contact times were examined for two source waters with different dissolved organic carbon(DOC) and bromide/iodide. For the low DOC water at pH 7 and 8, an optimized free chlorine contact time of up to 1 h could control regulated THMs and HAAs, as well as iodo-DBPs and NDMA. For the high DOC water, a free chlorine contact time of 5 min could control iodo-DBPs and NDMA at both p Hs, but the regulated DBPs could exceed the regulations at pH 7.
文摘Copper-based pesticides and wood preservatives could end up in the environment during production,use,and end-of-life via different pathways that could cause unintended ecolog-ical and adverse health effects.This paper provides the effect of colloid-size Cu-based pesti-cides(CuPRO and Kocide),micronized Cu azole(MCA-1 and MCA-2)and alkaline Cu quater-nary(ACQ)treated woods,Cu^(2+),Cu^(2+) spiked untreated wood(UTW),and CuCO_(3) solutions against Gram-positive Bacillus species using five-day biochemical oxygen demand(BOD 5)stan-dard test.The total Cu leached from MCA-1,MCA-2,and ACQ in Milli-Q water after 5 days were -0.1,-0.11,and -0.64 g/kg of wood,respectively.However,the form of Cu leached from MCA woods was mostly ionic(>90%).The total organic carbon(TOC)content of any tested wood(UTW/MCA-1/MCA-2/ACQ)was -99%of its corresponding total carbon(TC)content,whereas the TOC of any tested wood sawdust exceeded that of its corresponding piece/block by>300%.The dissolved oxygen(DO)consumption value in the presence of Cu^(2+),CuCO_(3),CuPRO,and Kocide solutions was significantly influenced by Cu particles/ions.However,the DO consumption value in the presence of UTW/MCA-1/MCA-2/ACQ woods was significantly influenced by organics leached from woods.On the other hand,the DO consumption of MCA sawdust was greater than(300%)that of MCA pieces/block.The findings of this study provide more insight into how organics leached from woods significantly reduce the toxic effects of Cu ions against Gram-positive Bacillus species.
文摘Background:Perfluorooctanoic acid(PFOA)is an environmental contaminant associated with adverse metabolic outcomes in developmentally exposed human populations and mouse models.Hexafluoropropylene oxide-dimer acid(HFPO-DA,commonly called GenX)has replaced PFOA in many industrial applications in the U.S.and Europe and has been measured in global water systems from<1 to 9350 ng/L HFPO-DA.Health effects data for GenX are lacking.Objective:Determine the effects of gestational exposure to GenX on offspring weight gain trajectory,adult metabolic health,liver pathology and key adipose gene pathways in male and female CD-1 mice.Methods:Daily oral doses of GenX(0.2,1.0,2.0 mg/kg),PFOA(0.1,1.0 mg/kg),or vehicle control were administered to pregnant mice(gestation days 1.5-17.5).Offspring were fed a high-or low-fat diet(HFD or LFD)at weaning until necropsy at 6 or 18 weeks,and metabolic endpoints were measured over time.PFOA and GenX serum and urine concentrations,weight gain,serum lipid parameters,body mass composition,glucose tolerance,white adipose tissue gene expression,and liver histopathology were evaluated.Results:Prenatal exposure to GenX led to its accumulation in the serum and urine of 5-day old pups(P=0.007,P<0.001),which was undetectable by weaning.By 18 weeks of age,male mice fed LFD in the 2.0 mg/kg GenX group displayed increased weight gain(P<0.05),fat mass(P=0.016),hepatocellular microvesicular fatty change(P=0.015),and insulin sensitivity(P=0.014)in comparison to control males fed LFD.Female mice fed HFD had a significant increase in hepatocyte single cell necrosis in 1.0 mg/kg GenX group(P=0.022)and 1.0 mg/kg PFOA group(P=0.003)compared to control HFD females.Both sexes were affected by gestational GenX exposure;however,the observed phenotype varied between sex with males displaying more characteristics of metabolic disease and females exhibiting liver damage in response to the gestational exposure.Conclusions:Prenatal exposure to 1 mg/kg GenX and 1 mg/kg PFOA induces adverse metabolic outcomes in adult mic
文摘Short-term tests for mutagenicity(also referred to as short-term tests for genetic toxicity)have been used extensively toidentify mutagens and potential carcinogens.Increasingly,the sameshort-term tests are being used to identify antimutagens andpotential anticarcinogens.The data on antimutagenicity are comolexin part because of three simultaneous experimental variables:themutagens(and/or spontaneous mutation)studied,the antimutagensstudied,and the short-term tests used.In order to summarize anddisplay these complex published data on antimutagenicity,wedeveloped the concept of 'activity profiles for antimutagens'('antimutagenicity profiles')(Waters et al.1990,Brockman et al.1992).An antimutagenicity profile is composed of two parallel setsof bargraphs.For each combination of antimitagen,mutagen,andshort-term test displayed,the upper graph displays the mutagenconcentrations tested,whereas the lower graph displays the result asmaximum percent inhibition,maximum percent enhancement,or noeffect.The
文摘 Hydrogen peroxide (H2O2 ) concentrations were measured at two sites. One was on Lushan Mountain in May, 1987. The other was in Beijing in August, 1987 and in December, 1986. The automated fluorometric method was used for the determination of H2O2 . The concentrations of H2O2 ranged from approximately 0.50 to 4.32 ppb on Lushan Mountain. The concentrations of H2O2 ranged from approximately 0.05 to 1.49 ppb in August in Beijing, and it was only 0.01 ppb in December in Beijing.
文摘Low levels (ng/g) of musk ketone (MK),used as a fragrance additive in the formulation of personal care products,are frequently detected in the water and other environment.Thus,aquatic organisms can be continuously exposed to MK.In this study,kinetics and dose-response assessments of 2-amino-MK (AMK) metabolite,bound to cysteine-hemoglobin (Hb) in rainbow trout,formed by enzymatic nitro-reduction of MK have been demonstrated.Trout were exposed to a single exposure of 0.010,0.030,0.10,and 0.30 mg MK/g fish.Tw...
文摘In this study,a new analytical technique was developed for the identification and quantification of multifunctional compounds containing simultaneously at least one hydroxyl or one carboxylic group,or both.This technique is based on derivatizing first the carboxylic group(s) of the multifunctional compound using an alcohol (e.g.,methanol,1-butanol) in the presence of a relatively strong Lewisacid (BF3) as a catalyst.This esterification reaction quickly and quantitatively converts carboxylic acids to their ester forms.The second step is based on silylation of the ester compounds using bis(trimethylsilyl) trifluoroacetamide (BSTFA) as the derivatizing agent.For compounds bearing ketone groups in addition to carboxylic and hydroxyl groups,a third step was used based on PFBHA derivatizationof the carbonyls.Different parameters including temperature,reaction time,and effect due to artifacts were optimized.A GC/MS in EI and in methane-CI mode was used for the analysis of these compounds.The new approach was tested on a number of multifunctional compounds.The interpretation of their EI (70 eV) and CI mass spectra shows that critical information is gained leading to unambiguous identification of unknown compounds.For example,when derivatized only with BF3-methanol,their mass spectra comprise primary ions at m/z M ·+ +1,M ·+ +29,and M ·+ - 31 for compounds bearing only carboxylic groups and M ·+ +1,M ·+ +29,M ·+ -31,and M ·+ -17 for those bearing hydroxyl andcarboxylic groups.However,when a second derivatization (BSTFA) was used,compounds bearing hydroxyl and carboxylic groups simultaneously show,in addition to the ions observed before,ions at m/z M ·+ +73,M ·+ -15,M ·+ -59,M ·+ -75,M ·+ -89,and 73.To the best of our knowledge,this technique describes systematically for the first time a method for identifying multifunctional oxygenated compounds containing simultaneously one or more hydroxyl and carboxylic acid groups.
文摘The short-term tests (STT) that have been usedsuccessfully to identify mutagens and potentialcarcinogens increasingly are being used to identifyantimutagens and potential anticarcinogens.Theconcept of activity profiles,already appliedsuccessfully to the display of mutagenicity
