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981.
Diamando Vlachogiannis Spyros Andronopoulos Artemis Passamichali Nikos Gounaris John G. Bartzis 《Environmental monitoring and assessment》2000,65(1-2):41-48
This study concentrated on the effects of Biogenic Volatile Organic Compounds (BVOC) emissions on ozone (O3) in an area of the Eastern Spain on June 12, 1997, a day characterised by sea breeze. Simulation of meteorology was performed with the three-dimensional model ADREA-I. Comparisons of the model results with observations have revealed overall a good agreement in temperature and wind velocity. Two runs were performed with UAM-IV for the photochemical calculations. The first simulated the effects of the anthropogenic emissions only (run A) and the second the combined effects of anthropogenic and biogenic emissions, (run B). Comparisons of the model O3 concentrations with measurements showed a general agreement with the experimental data. Discrepancies between the calculated results and the observations during the early morning hours could be attributed to inaccuracies in nitrogen oxides (NOx) from the anthropogenic emissions inventory. Comparisons between runs A and B yielded differences up to 30% in the morning, over inland areas. It was deduced that the inclusion of BVOC in total emissions could result in an increase or decrease of tropospheric O3, depending on the available amounts of anthropogenic emissions. 相似文献
982.
颗粒态重金属通过河流与大气向海洋输送 总被引:8,自引:2,他引:8
本文综述了河流与大气向海洋输送颗态重金属的过程、特点及输送通量、参考文献83篇。 相似文献
983.
An improved implementation of distributed multiplier/fictitious domain method is presented for the direct numerical simulation of particulate flow. The key improvement is to replace a finite-element triangulation for the velocity and a “twice-coarser“ triangulation for the pressure with a rectangular discretization for the velocity and pressure. For code validation, the sedimentation of a single particle in a twodimensional channel was simulated. The results showed that the simulation is independent of the mesh size as well as the time step. The comparison between experimental data and this simulation showed that our code can give a more accurate simulation on the motion of particlesthan previous DLM code. The code was then applied to simulate the sedimentation of 600 particles in a rectangular box. The falling course ispresented and discussed. At the same time, this simulation also demonstrates that the method presented in this paper can be used for solving the initial problems involving a lager number of particles exaclly with computing durations kept at acceptable levels. 相似文献
984.
N2O emissions from agricultural soils in the North China Plain:the effect of chemical nitrogen fertilizer and organic manure 总被引:1,自引:0,他引:1
IntroductionNitrousoxide (N2 O)isaveryimportantgreenhousegasintheatmosphere.InterestintheincreaseofatmosphericN2 OhasbeenrecentlystimulatedbytheunderstandingthatN2 Ogasplaysanimportantroleinthechemistryandozonelayerdestructionofthestratosphere.Theradiativ… 相似文献
985.
污泥上清液的有机物浓度及其生物降解性 总被引:2,自引:0,他引:2
在进行城市生活污水的生物处理过程中,会产生一定量的生化污泥。在浓缩和处理剩余污泥时,所产生的含高浓度有机物的污泥上清液被回流到污水处理系统,不适当的回流会增加水处理系统的负荷并严重影响,出水的水质。实验证明,在污泥浓缩中,污泥上清液中有机物含有与浓缩温度成e指数关系,与浓缩时间成小于1的指数关系。 相似文献
986.
987.
Tim Chatterton Stephen Dorling Andrew Lovett Michael Stephenson 《Water, Air, & Soil Pollution: Focus》2002,2(5-6):173-187
This study uses a combination of data from U.K. monitoringstations and from modelling undertaken with the U.K.Meteorological Office's NAME Model to investigate therelative influences of primary and secondary particulateson total PM10 levels at sites in the United Kingdom. Co-located PM10 and sulphate aerosol measurementsindicate that sulphate has a disproportionately largeinfluence on the variation of PM10 levels incomparison to its contribution to their total mass.Comparisons of measured PM10 at urban centre, roadsideand rural sites suggest that local primary sources havevery little influence on daily mean levels. NAME has beenused to model both primary particles and sulphate aerosolfrom sources across the whole of Europe. The discrepanciesbetween modelled and observed PM10 suggest that coarseparticles, such as windblown dust and resuspended roaddust,may comprise a very large, if not dominant, proportion ofobserved PM10 levels. The apparently minor role ofprimary particles (especially locally-sourced ones) raisesa number of issues regarding the suitability of current U.K.and European legislation to addressing the particle problem. 相似文献
988.
Stefano Cordiner Renato Baciocchi Marina Attinà 《Water, Air, & Soil Pollution: Focus》2002,2(5-6):573-585
The prediction of the atmospheric concentration of ozoneand of other photochemical pollutants represents one of themajor scientific challenges in the study of urban airquality. To this aim, photochemical models are widelyapplied as support tools for regulatory purposes, but theirresults are known to be affected by several uncertainties,in boundary conditions, geographical and meteorologicaldata and the chemical composition of emission and ambientair as well. Also the mechanism selected to describe theurban chemistry may lead to large differences in the modelresults. In this work, the influence of ambient air composition onthe results of photochemical model has been studied using a simple Lagrangian trajectory model coupled with different chemical sub-models (CB-IV and a simplified version of EMEP). To this aim a parametric sensitivity study of ozone with respect to its precursors' concentration was performed withreference to the same meteorological conditions and by simulatingdifferent scenarios characterized by specific emitted pollutantsconcentration. Rather than analyzing sensitivity by changing initial composition, an analytical local sensitivity concept has been applied; this allowed evaluation the influence of initial concentration on the predicted ozone concentration andto discriminate between VOC-sensitive and NOx-sensitive kineticregimes. Finally, these results have been successfully comparedwith those obtained applying the concept of photochemical indicators (i.e. O3/NOy and H2O2/HNO3 ratios). 相似文献
989.
Peter M. Kiffney Jennifer P. Bull Michael C. Feller 《Journal of the American Water Resources Association》2002,38(5):1437-1451
ABSTRACT: Climate data from the Malcolm Knapp Research Forest (MKRF) in the Coast Range mountains of southwestern British Columbia were used to examine relationships between climate and hydrology and variations in the El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO). Air and water temperatures were higher and precipitation was lower during in‐phase or warm PDO/E1 Niño events than in other years. In contrast, in‐phase or cool PDO/La Niña years were generally cooler and wetter than other years. Precipitation and East Creek discharge were positively related to the Southern Oscillation Index (SOI) and negatively related to the PDO index. Conversely, air and water temperatures were negatively related to the SOI and positively related to the PDO index. Differences in precipitation and air temperature were also evident at longer time scales when separated by PDO phase. Because of drier conditions during in‐phase El Niño events, the flow of organic matter from East Creek to downstream portions of the channel network was lower compared to other years. This reduction has implications for downstream communities, as these subsidies provide a major source of energy for stream food webs. Therefore, short term and long term shifts in climate, discharge, and water temperature may have profound impacts on the ecology of Pacific Northwest (PNW) watersheds due to changes in a number of ecosystem processes such as altered flux of organic matter from headwater streams to larger rivers. 相似文献
990.
Biomass burning associated with shifting cultivation areas from the northeastern region of India is an important source of trace gas emissions in the Southeast Asian region. In the present study, satellite data pertaining to IRS-P4 OCM data and DMSP-OLS has been used to quantify the intensity, areal extent and amount of biomass burnt in the northeastern region states at district level. Trace gas emissions have been quantified both by using IPCC based emission ratios and ground based emission ratios obtained from field based studies. Areal estimates with respect to shifting cultivation areas from IRS-P4 OCM satellite data of 4th April 2000 suggested nearly 112.99 km2 of the northeastern region of India affected due to shifting cultivation. In the study, DMSP OLS nighttime data has been used to capture the real time fires during the dry season. The results suggested high amount of fires during the March season when compared to April and May. Using the emission ratios obtained from the ground-based studies and IPCC emission ratios, the emissions for the individual non-CO2 trace gases have been computed in a GIS framework using the biomass data, combustion factors and emission ratios. Results suggested emissions of 2.063 Mt CH4, 17.94 Mt CO, 1.419 Mt N2O, and 51.28 Mt NO
x
and 2.643 Mt release of CH4, 3.7204 Mt CO, 0.145 Mt N2O, and 8.477 Mt NO
x
, respectively, from biomass burning due to shifting cultivation for the year 2000, from the northeastern region in India. The study highlights the importance of Satellite Remote sensing data and GIS in quantifying the trace gas emissions from biomass burning. 相似文献