A field campaign was carried out to investigate continuous diel methane(CH_4) flux from a subtropical eutrophic pond in November 2016. The diffusive methane flux of a single measurement had a range from2.68 9 10-5 to ...A field campaign was carried out to investigate continuous diel methane(CH_4) flux from a subtropical eutrophic pond in November 2016. The diffusive methane flux of a single measurement had a range from2.68 9 10-5 to 0.028 mmol·m^(-2)·h^(-1) with an average of0.011 ± 0.005 mmol·m^(-2)·h^(-1). The diffusive methane flux of measurements from 9:00 to 10:30 and from 21:00 to22:30 were very close to the average diffusive flux of all measurements. The bubble methane flux at different time measurements had much more variability than the diffusive methane flux. The bubble methane flux of a single measurement had a range from 0 to 0.312 mmol·m^(-2)·h^(-1) with an average of 0.024 ± 0.054 mmol·m^(-2)·h^(-1). For the eutrophic pond, the average bubble and diffusive CH_4 flux were 0.56 ± 0.18 and 0.26 ± 0.04 mmol·m^(-2)·day^(-1),respectively, and the CH_4 ebullition flux accounted for68.23% of the total flux. The maximum of the bubble CH_4 flux was about 4.6 times of the minimum CH_4 ebullition.The maximum of diffusive CH_4 flux was * 1.7 times of the corresponding minimum. The diffusive methane fluxes in daytime and nighttime were almost equal. However, the bubble methane flux in daytime was 0.029 mmol·m^(-2)·h^(-1),which was 1.6 times of that at night. Wind speed, thesurface water temperature, and DO dominate methane effluxes from the pond, and the latter is in nature subjected to the metabolism of algae in the pond. However, key environmental factors which dominate gas flux processes vary with different weather conditions. Wind speed is unimportant when it is extremely low.展开更多
Health risks assessment due to exposure to organic contaminated soil at an oil refinery out of service is conducted in this study by integrating health risk methods of U.S. EPA （United States Environmental Protection...Health risks assessment due to exposure to organic contaminated soil at an oil refinery out of service is conducted in this study by integrating health risk methods of U.S. EPA （United States Environmental Protection Agency）, ASTM （American Society for Testing and Materials） and VROM （Ministry of Housing, Spatial Planning and the Environment in Netherlands）, with the localized parameters using Chinese demographic characteristics and site features. The monitoring results show that the concentration of benzene, benzo（a）pyrene and benzo（a）anthracene in the soil of the site all exceed their risk screening values, respectively, with pollutants concentrated in soil 0.1-5.5 m beneath the surface. To estimate health risks of the site with the 95% upper confidence limit of the pollution, we focus on three major exposure pathways, namely, oral ingestion, dermal contact and breath inhalation, which indicates carcinogenic risk （CR） and non-carcinogenic hazard quotient （HQ） of the contaminated soil reach 9.59×10^-5 and 15.46, respectively, exceeding the acceptable level of 10^5 and 1, posing severe health hazards to the residents at the site. KEY WORDS： contaminated site, health risk, soil, organic contamination.展开更多
基金financially supported by the National Science of China (Nos. 41273110, 91647207, and 51509086)Natural Science Foundation of Hubei Province, China (2014CFB672)
文摘A field campaign was carried out to investigate continuous diel methane(CH_4) flux from a subtropical eutrophic pond in November 2016. The diffusive methane flux of a single measurement had a range from2.68 9 10-5 to 0.028 mmol·m^(-2)·h^(-1) with an average of0.011 ± 0.005 mmol·m^(-2)·h^(-1). The diffusive methane flux of measurements from 9:00 to 10:30 and from 21:00 to22:30 were very close to the average diffusive flux of all measurements. The bubble methane flux at different time measurements had much more variability than the diffusive methane flux. The bubble methane flux of a single measurement had a range from 0 to 0.312 mmol·m^(-2)·h^(-1) with an average of 0.024 ± 0.054 mmol·m^(-2)·h^(-1). For the eutrophic pond, the average bubble and diffusive CH_4 flux were 0.56 ± 0.18 and 0.26 ± 0.04 mmol·m^(-2)·day^(-1),respectively, and the CH_4 ebullition flux accounted for68.23% of the total flux. The maximum of the bubble CH_4 flux was about 4.6 times of the minimum CH_4 ebullition.The maximum of diffusive CH_4 flux was * 1.7 times of the corresponding minimum. The diffusive methane fluxes in daytime and nighttime were almost equal. However, the bubble methane flux in daytime was 0.029 mmol·m^(-2)·h^(-1),which was 1.6 times of that at night. Wind speed, thesurface water temperature, and DO dominate methane effluxes from the pond, and the latter is in nature subjected to the metabolism of algae in the pond. However, key environmental factors which dominate gas flux processes vary with different weather conditions. Wind speed is unimportant when it is extremely low.
基金supported by Three Gold City Real Estate Development Co. LTD.,Wuhan (No. 2009046268)
文摘Health risks assessment due to exposure to organic contaminated soil at an oil refinery out of service is conducted in this study by integrating health risk methods of U.S. EPA （United States Environmental Protection Agency）, ASTM （American Society for Testing and Materials） and VROM （Ministry of Housing, Spatial Planning and the Environment in Netherlands）, with the localized parameters using Chinese demographic characteristics and site features. The monitoring results show that the concentration of benzene, benzo（a）pyrene and benzo（a）anthracene in the soil of the site all exceed their risk screening values, respectively, with pollutants concentrated in soil 0.1-5.5 m beneath the surface. To estimate health risks of the site with the 95% upper confidence limit of the pollution, we focus on three major exposure pathways, namely, oral ingestion, dermal contact and breath inhalation, which indicates carcinogenic risk （CR） and non-carcinogenic hazard quotient （HQ） of the contaminated soil reach 9.59×10^-5 and 15.46, respectively, exceeding the acceptable level of 10^5 and 1, posing severe health hazards to the residents at the site. KEY WORDS： contaminated site, health risk, soil, organic contamination.
