A recent study by the Environmental Working Group reported the detection of hexavalent chromium (Cr(VI)) in tap water at 31 out of 35 states investigated in the United States. Even though Cr(III) is an essential eleme...A recent study by the Environmental Working Group reported the detection of hexavalent chromium (Cr(VI)) in tap water at 31 out of 35 states investigated in the United States. Even though Cr(III) is an essential element for human diet, Cr(VI) is a potential carcinogen. Previous work has clearly identified a linear trend of increasing risk of lung cancer mortality with increasing cumulative exposure to water soluble Cr(VI). Regardless, Cr(VI) is still not regulated or monitored in drinking water in the U.S. There is an existing method (EPA 218.6) for the analysis of Cr(VI), however, this analytical method does not addresses detailed sample preservation techniques and optimization process to achieve lowest detection limit possible. In this study, five buffer solutions with pH of 9 and above were compared to determine the most suitable buffer to preserve Cr(VI) in drinking water samples for an extended period of time. Results showed that the five buffers responded very differently to Cr(VI)-fortified drinking water. The best preserving reagent was found to be Ammonium Hydroxide + Ammonium Sulfate (pH 9.2) and Sodium Carbonate + Sodium Bicarbonate+ Ammonium Sulfate (pH 9.7), whereas a buffer solution with Sodium Hydroxide + Sodium Carbonate (pH 11.5+) resulted in a poor chromatographic resolution. A controlled study with a fortified Cr(III) at 1 ppb was also conducted to ensure no false positive detection of Cr(VI) due to the potential oxidation of Cr(III) during sample storage. The optimal preserving reagent identified from this study was compatible with the existing EPA method 218.6 using ion chroma-tography followed by post column reaction, with a method quantitation limit of 0.020 ppb and matrix spike recovery of ± 10%.展开更多
The under-sampled middle and western branches of Shade River Watershed (SRW) in SE Ohio were investigated as part of the Ohio University—U.S. Environmental Protection Agency (EPA) STAR grant. This project was for mon...The under-sampled middle and western branches of Shade River Watershed (SRW) in SE Ohio were investigated as part of the Ohio University—U.S. Environmental Protection Agency (EPA) STAR grant. This project was for monitoring the quality of watersheds in Ohio and classifying them according to their physical, chemical, and biological conditions. Water samples, as well as field parameters, were taken at twenty-two sites for chemical analyses. The ions analyzed included Ca, Mg, Na, Fe, Mn, Al, NO3, SO4, HCO3, and total PO4, while the field parameters measured included pH, dissolved oxygen (DO), total dissolved solids (TDS), electrical conductivity (EC), and alkalinity. To assess the water quality within the SRW, the analyzed ions and field parameters were compared to the USEPA criteria for the survival of aquatic life. Analytical results showed that the watershed is dominated by Ca-HCO3waters with DO, Fe, Mn, and PO4being the main causes of impairment within the streams. The relatively elevated concentrations of manganese and less extent iron may be associated with the local geology and the acidic nature of the soils. The high alkalinity and calcium concentrations are due to the limestone geology. The elevated phosphate concentration may be due to anthropogenic sources, fertilizers, or contributions from phosphorus-rich bedrock that differs geochemically from other areas.展开更多
A state-of-the-art wind erosion simulation model,the Wind Erosion Prediction System and the United States Environmental Protection Agency's AP 42 emission factors formula,were combined together to evaluate wind-bl...A state-of-the-art wind erosion simulation model,the Wind Erosion Prediction System and the United States Environmental Protection Agency's AP 42 emission factors formula,were combined together to evaluate wind-blown dust emissions from various construction units from a railway construction project in the dry Gobi land in Northwest China.The influence of the climatic factors:temperature,precipitation,wind speed and direction,soil condition,protective measures,and construction disturbance were taken into account.Driven by daily and sub-daily climate data and using specific detailed management fles,the process-based WEPS model was able to express the beginning,active,and ending phases of construction,as well as the degree of disturbance for the entire scope of a construction project.The Lanzhou-Xinjiang High-speed Railway was selected as a representative study because of the diversities of different cli-mates,soil,and working schedule conditions that could be analyzed.Wind erosion from different working units included the building of roadbeds,bridges,plants,temporary houses,earth spoil and barrow pit areas,and vehicle transportation were calculated.The total wind erosion emissions,7406 t,for the first construction area of section LXS-15 with a 14.877 km length was obtained for quantitative analysis.The method used is applicable for evaluating wind erosion from other complex surface dis-turbance projects.展开更多
This study was conducted to explore the major sources of pollutants including total suspended particles and levels of NOx,COx,and SOx in Faisalabad Pakistan,which make key contributions to the smog in Faisalabad.Faisa...This study was conducted to explore the major sources of pollutants including total suspended particles and levels of NOx,COx,and SOx in Faisalabad Pakistan,which make key contributions to the smog in Faisalabad.Faisalabad is the third largest city of Pakistan where the situation is aggravating due to industrial expansion,population growth and an increasing volume of traffic.Study was conducted for the period of three months at different stations in Faisalabad.The concentrations of total suspended particles,levels of NOx,SOx and COx are 160μg/m^(3) to 506μg/m^(3),26μg/m^(3) to 64μg/m^(3),110μg/m^(3) to 139μg/m^(3) and 5.5 mg/m^(3) to 18.2 mg/m^(3),respectively.As a result,air pollution control should not simply focus on controlling particulate emission,but also involve adopting an integrated multi-pollutant control strategy.Measured concentrations were at an intermediate level with respect to parameters by using Geographical Information System(GIS)and GPS.The results were compared with the permissible limits of United States Environmental Protection Agency(USEPA)and National Environmental Quality Standards(NEQS).展开更多
文摘A recent study by the Environmental Working Group reported the detection of hexavalent chromium (Cr(VI)) in tap water at 31 out of 35 states investigated in the United States. Even though Cr(III) is an essential element for human diet, Cr(VI) is a potential carcinogen. Previous work has clearly identified a linear trend of increasing risk of lung cancer mortality with increasing cumulative exposure to water soluble Cr(VI). Regardless, Cr(VI) is still not regulated or monitored in drinking water in the U.S. There is an existing method (EPA 218.6) for the analysis of Cr(VI), however, this analytical method does not addresses detailed sample preservation techniques and optimization process to achieve lowest detection limit possible. In this study, five buffer solutions with pH of 9 and above were compared to determine the most suitable buffer to preserve Cr(VI) in drinking water samples for an extended period of time. Results showed that the five buffers responded very differently to Cr(VI)-fortified drinking water. The best preserving reagent was found to be Ammonium Hydroxide + Ammonium Sulfate (pH 9.2) and Sodium Carbonate + Sodium Bicarbonate+ Ammonium Sulfate (pH 9.7), whereas a buffer solution with Sodium Hydroxide + Sodium Carbonate (pH 11.5+) resulted in a poor chromatographic resolution. A controlled study with a fortified Cr(III) at 1 ppb was also conducted to ensure no false positive detection of Cr(VI) due to the potential oxidation of Cr(III) during sample storage. The optimal preserving reagent identified from this study was compatible with the existing EPA method 218.6 using ion chroma-tography followed by post column reaction, with a method quantitation limit of 0.020 ppb and matrix spike recovery of ± 10%.
文摘The under-sampled middle and western branches of Shade River Watershed (SRW) in SE Ohio were investigated as part of the Ohio University—U.S. Environmental Protection Agency (EPA) STAR grant. This project was for monitoring the quality of watersheds in Ohio and classifying them according to their physical, chemical, and biological conditions. Water samples, as well as field parameters, were taken at twenty-two sites for chemical analyses. The ions analyzed included Ca, Mg, Na, Fe, Mn, Al, NO3, SO4, HCO3, and total PO4, while the field parameters measured included pH, dissolved oxygen (DO), total dissolved solids (TDS), electrical conductivity (EC), and alkalinity. To assess the water quality within the SRW, the analyzed ions and field parameters were compared to the USEPA criteria for the survival of aquatic life. Analytical results showed that the watershed is dominated by Ca-HCO3waters with DO, Fe, Mn, and PO4being the main causes of impairment within the streams. The relatively elevated concentrations of manganese and less extent iron may be associated with the local geology and the acidic nature of the soils. The high alkalinity and calcium concentrations are due to the limestone geology. The elevated phosphate concentration may be due to anthropogenic sources, fertilizers, or contributions from phosphorus-rich bedrock that differs geochemically from other areas.
基金supported by the National Science Foundation of China(41501008),the Youth Innovation Promotion Association(2016373)and the“Light of West China”Program of the Chinese Academy of Sciences.
文摘A state-of-the-art wind erosion simulation model,the Wind Erosion Prediction System and the United States Environmental Protection Agency's AP 42 emission factors formula,were combined together to evaluate wind-blown dust emissions from various construction units from a railway construction project in the dry Gobi land in Northwest China.The influence of the climatic factors:temperature,precipitation,wind speed and direction,soil condition,protective measures,and construction disturbance were taken into account.Driven by daily and sub-daily climate data and using specific detailed management fles,the process-based WEPS model was able to express the beginning,active,and ending phases of construction,as well as the degree of disturbance for the entire scope of a construction project.The Lanzhou-Xinjiang High-speed Railway was selected as a representative study because of the diversities of different cli-mates,soil,and working schedule conditions that could be analyzed.Wind erosion from different working units included the building of roadbeds,bridges,plants,temporary houses,earth spoil and barrow pit areas,and vehicle transportation were calculated.The total wind erosion emissions,7406 t,for the first construction area of section LXS-15 with a 14.877 km length was obtained for quantitative analysis.The method used is applicable for evaluating wind erosion from other complex surface dis-turbance projects.
文摘This study was conducted to explore the major sources of pollutants including total suspended particles and levels of NOx,COx,and SOx in Faisalabad Pakistan,which make key contributions to the smog in Faisalabad.Faisalabad is the third largest city of Pakistan where the situation is aggravating due to industrial expansion,population growth and an increasing volume of traffic.Study was conducted for the period of three months at different stations in Faisalabad.The concentrations of total suspended particles,levels of NOx,SOx and COx are 160μg/m^(3) to 506μg/m^(3),26μg/m^(3) to 64μg/m^(3),110μg/m^(3) to 139μg/m^(3) and 5.5 mg/m^(3) to 18.2 mg/m^(3),respectively.As a result,air pollution control should not simply focus on controlling particulate emission,but also involve adopting an integrated multi-pollutant control strategy.Measured concentrations were at an intermediate level with respect to parameters by using Geographical Information System(GIS)and GPS.The results were compared with the permissible limits of United States Environmental Protection Agency(USEPA)and National Environmental Quality Standards(NEQS).
