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721.
光电技术在大气氮氧化物检测中的应用 总被引:5,自引:0,他引:5
介绍了大气中氮氧化物的组成,综述了激光诱导荧光法、光纤传感法、激光雷达探测法和化学发光法测定大气中氮氧化物的原理和特点,指出光电技术已在大气氮氧化物检测中得到了广泛的应用,并具有良好的发展前景。 相似文献
722.
Jeane G. Francisco Rodrigo F. Pimpinato Valdemar L. Tornisielo Ana C. D. Guimarães 《Journal of environmental science and health. Part. B》2017,52(7):470-475
This study aimed to evaluate the sorption-desorption and leaching of aminocyclopyrachlor from three Brazilian soils. The sorption-desorption of 14C-aminocyclopyrachlor was evaluated using the batch method and leaching was assessed in glass columns. The Freundlich model showed an adequate fit for the sorption-desorption of aminocyclopyrachlor. The Freundlich sorption coefficient [Kf (sorption)] ranged from 0.37 to 1.34 µmol (1–1/n) L1/n kg?1 and showed a significant positive correlation with the clay content of the soil, while the Kf (desorption) ranged from 3.62 to 5.36 µmol (1–1/n) L1/n kg?1. The Kf (desorption) values were higher than their respective Kf (sorption), indicating that aminocyclopyrachlor sorption is reversible, and the fate of this herbicide in the environment can be affected by leaching. Aminocyclopyrachlor was detected at all depths (0?30 cm) in all the studied soils, where leaching was influenced by soil texture. The total herbicide leaching from the sandy clay and clay soils was <0.06%, whereas, ~3% leached from the loamy sand soil. The results suggest that aminocyclopyrachlor has a high potential of leaching, based on its low sorption and high desorption capacities. Therefore, this herbicide can easily contaminate underground water resources. 相似文献
723.
Rising human demand and climatic variability have created greater uncertainty regarding global food trade and its effects on the food security of nations. To reduce reliance on imported food, many countries have focused on increasing their domestic food production in recent years. With clear goals for the complete self-sufficiency of rice production, Sri Lanka provides an ideal case study for examining the projected growth in domestic rice supply, how this compares to future national demand, and what the associated impacts from water and fertilizer demands may be. Using national rice statistics and estimates of intensification, this study finds that improvements in rice production can feed 25.3 million Sri Lankans (compared to a projected population of 23.8 million people) by 2050. However, to achieve this growth, consumptive water use and nitrogen fertilizer application may need to increase by as much as 69 and 23 %, respectively. This assessment demonstrates that targets for maintaining self-sufficiency should better incorporate avenues for improving resource use efficiency.
Electronic supplementary material
The online version of this article (doi:10.1007/s13280-015-0720-2) contains supplementary material, which is available to authorized users. 相似文献724.
725.
Responses of CH(4), CO(2) and N(2)O fluxes to increasing nitrogen deposition in alpine grassland of the Tianshan Mountains 总被引:2,自引:0,他引:2
To assess the effects of nitrogen (N) deposition on greenhouse gas (GHG) fluxes in alpine grassland of the Tianshan Mountains in central Asia, CH4, CO2 and N2O fluxes were measured from June 2010 to May 2011. Nitrogen deposition tended to significantly increase CH4 uptake, CO2 and N2O emissions at sites receiving N addition compared with those at site without N addition during the growing season, but no significant differences were found for all sites outside the growing season. Air temperature, soil temperature and water content were the important factors that influence CO2 and N2O emissions at year-round scale, indicating that increased temperature and precipitation in the future will exert greater impacts on CO2 and N2O emissions in the alpine grassland. In addition, plant coverage in July was also positively correlated with CO2 and N2O emissions under elevated N deposition rates. The present study will deepen our understanding of N deposition impacts on GHG balance in the alpine grassland ecosystem, and help us assess the global N effects, parameterize Earth System models and inform decision makers. 相似文献
726.
727.
为了遏制水环境不断恶化的趋势,应加强对氮、磷超标的治理工作,促进水生态环境平衡发展。本文采用A^2/O-MBR作为主体工艺,后续辅以化学除磷和以深床滤池为反硝化单元的组合工艺,确保最终出水满足天津市《城镇污水处理厂污染物排放标准》(DB12/599-2015)A标准排放要求。 相似文献
728.
Natalia Valero Inmaculada Aguilera Sabrina Llop Ana Esplugues Audrey de Nazelle Ferran Ballester Jordi Sunyer 《Environment international》2009,35(8):1196-1201
Determinants of outdoor, indoor and personal concentrations of nitrogen dioxide (NO2) were assessed in a subset of pregnant women of the Spanish INMA (Environment and Childhood) Study. Home indoor and outdoor NO2 concentrations were measured during 48 h with passive samplers for 50 and 58 women from the INMA cohorts of Valencia and Sabadell, respectively. Women from Sabadell also carried personal NO2 samplers during the same period. Data on time–activity patterns, socio-economic characteristics, and environmental exposures were obtained through questionnaires. Multiple linear regression models were developed to predict NO2 levels.In Valencia, median outdoor NO2 levels (42 µg/m3) were higher than median indoor levels (36 µg/m3). In Sabadell, personal NO2 showed the highest median levels (40 µg/m3), followed by indoor (32 µg/m3) and outdoor (29 µg/m3) levels. Personal exposure to NO2 correlated best with the indoor NO2 levels. Temporal and traffic-related variables were significant predictors for outdoor NO2 levels. Thirty-two percent of the indoor NO2 variability in the two cohorts was explained by outdoor NO2 levels and the use of the gas appliances. The model for personal exposure accounted for 59% of the variance in NO2 levels in Sabadell with four predictor variables (outdoor and indoor NO2 levels, time spent in outdoor environments and time exposed to a gas cooker). No significant association was found between personal or indoor NO2 levels and exposure to environmental tobacco smoke (ETS) at home.Personal NO2 levels were found to be strongly influenced by indoor NO2 concentrations. The study supports the use of time–activity patterns along with indoor measurements to predict personal exposure to traffic-related air pollution. 相似文献
729.
C. Wagner G. Schuster J.N. Crowley 《Atmospheric environment (Oxford, England : 1994)》2009,43(32):5001-5008
The interaction of N2O5 with dispersed samples of Arizona Test Dust (ATD), Calcite (CaCO3) and quartz (SiO2) was investigated at varying relative humidity using an aerosol flow reactor. Reactive uptake coefficients, γ, obtained at close to zero relative humidity were (4.8 ± 0.7) × 10−3 for CaCO3, (8.6 ± 0.6) × 10−3 for Quartz and (9.8 ± 1.0) × 10−3 for ATD. In the case of calcite, evidence was obtained for an enhanced rate of uptake at relative humidities above ≈ 50%. The results are compared to literature values obtained using bulk substrates and to previous aerosol uptake data on Saharan dust. 相似文献
730.
A prediction-based approach to modelling temporal and spatial variability of traffic-related air pollution in Montreal, Canada 总被引:1,自引:0,他引:1
Dan L. Crouse Mark S. Goldberg Nancy A. Ross 《Atmospheric environment (Oxford, England : 1994)》2009,43(32):5075-5084
Concentrations of traffic-related air pollution can be highly variable at the local scale and can have substantial seasonal variability. This study was designed to provide estimates of intra-urban concentrations of ambient nitrogen dioxide (NO2) in Montreal, Canada, that would be used subsequently in health studies of chronic diseases and long-term exposures to traffic-related air pollution. We measured concentrations of NO2 at 133 locations in Montreal with passive diffusion samplers in three seasons during 2005 and 2006. We then used land use regression, a proven statistical prediction method for describing spatial patterns of air pollution, to develop separate estimates of spatial variability across the city by regressing NO2 against available land-use variables in each of these three periods. We also developed a “pooled” model across these sampling periods to provide an estimate of an annual average. Our modelling strategy was to develop a predictive model that maximized the model R2. This strategy is different from other strategies whose goal is to identify causal relationships between predictors and concentrations of NO2.Observed concentrations of NO2 ranged from 2.6 ppb to 31.5 ppb, with mean values of 12.6 ppb in December 2005, 14.0 ppb in May 2006, and 8.9 ppb in August 2006. The greatest variability was observed during May. Concentrations of NO2 were highest downtown and near major highways, and they were lowest in the western part of the city. Our pooled model explained approximately 80% of the variability in concentrations of NO2. Although there were differences in concentrations of NO2 between the three sampling periods, we found that the spatial variability did not vary significantly across the three sampling periods and that the pooled model was representative of mean annual spatial patterns. 相似文献