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711.
区域环境空气质量预报的一般方法和基本原则 总被引:14,自引:12,他引:2
为响应公众服务和环境管理对环境空气质量预报的迫切需求,中国环境监测总站率先在京津冀区域开展了区域环境空气质量预报测试。结合目前积累的预报经验和国内外相关研究,探索出区域空气质量预报的一般方法和基本原则,讨论了客观订正环节中大气扩散条件、污染源排放、物理化学过程和空气质量变化规律的分析方法及系统建立、结果确定、天气控制形势分析和信息表述等基本原则,以期为各地开展环境空气质量预报提供技术参考。 相似文献
712.
Gevaldo L. de Almeida Luiz C. G. Pimentel Renato M. Cotta 《Environmental Modeling and Assessment》2008,13(1):53-65
A transient two-dimensional advection–diffusion model describing the turbulent dispersion of pollutants in the atmosphere
has been solved via the Generalized Integral Transform Technique (GITT), by two different schemes. The first approach performs
numerical integration of the transformed system using available routines for initial value problems with automatic error control.
In spite of the time-consuming character of such a scheme, its flexibility allows the handling of problems involving time-dependent
meteorological parameters such as wind speed and eddy diffusivities. The second approach works fully analytically being thus
intrinsically more robust and economic, although not directly applicable in dealing with time-dependent parameters. For the
test problem used in this work, both methods agree very well with each other, as well as with a known analytical solution
for a simpler formulation used as benchmark. The impact of the longitudinal diffusivity on the stiffness of the ordinary differential
equation (ODE) system arising from the integral transformation has been assessed through the processing time demanded to solve
it when the numerical approach is used. The observed CPU times show that the analytical approach is clearly preferable unless
the problem involves time-dependent parameters. 相似文献
713.
A. M. O. Abdul Raheem F. A. Adekola I. O. Obioh 《Environmental Modeling and Assessment》2009,14(4):497-509
A combination of multivariate statistical methods including factor analysis, principal component analysis, principal component
regression, and multiple linear regression (MLR) were employed to evaluate the influence of seasons on the concentrations
of ozone, sulfur (IV) oxide, and oxides of nitrogen in ambient air of Nigerian cities of Lagos and Ilorin. The former city
is located in the coastal area, and it is highly congested with a high intensity of marine, vehicular, and industrial activities,
and the latter city is a medium size town, located in the central guinea savannah zone of Nigeria. Samples were collected
using a high-volume sampler from near the ground at various sites of diverse human and industrial activities, during wet and
dry seasons from 2003 to 2006. The PCA reveals three distinct groupings during the day for all data, which is a reflection
of different factors contributing to the atmospheric chemistry of these cities. The predicted ozone concentration values by
MLR agree fairly well with the measured data. The dependence of ozone on meteorological parameters including relative humidity,
air temperature, and sun exposure and the precursor pollutants depends on weather and the anthropogenic activities. The results
for the two cities indicate that reduction in the level of NO2 is accompanied by an increase in the level of ozone, suggesting the interconversion between the two via photochemical activity. 相似文献
714.
715.
上海市餐厨垃圾处理管理思路剖析 总被引:1,自引:0,他引:1
根据<上海市餐厨垃圾处理管理办法>,分析了加强餐厨垃圾处理管理的思路,包括对物流、资金流和信息流的控制,从而实现餐厨垃圾产生环节、收集运输环节、处置环节的有效监管,维护公共卫生安全. 相似文献
716.
717.
Paul J. Block Francisco Assis Souza Filho Liqiang Sun Hyun‐Han Kwon 《Journal of the American Water Resources Association》2009,45(4):828-843
Abstract: Water resources planning and management efficacy is subject to capturing inherent uncertainties stemming from climatic and hydrological inputs and models. Streamflow forecasts, critical in reservoir operation and water allocation decision making, fundamentally contain uncertainties arising from assumed initial conditions, model structure, and modeled processes. Accounting for these propagating uncertainties remains a formidable challenge. Recent enhancements in climate forecasting skill and hydrological modeling serve as an impetus for further pursuing models and model combinations capable of delivering improved streamflow forecasts. However, little consideration has been given to methodologies that include coupling both multiple climate and multiple hydrological models, increasing the pool of streamflow forecast ensemble members and accounting for cumulative sources of uncertainty. The framework presented here proposes integration and offline coupling of global climate models (GCMs), multiple regional climate models, and numerous water balance models to improve streamflow forecasting through generation of ensemble forecasts. For demonstration purposes, the framework is imposed on the Jaguaribe basin in northeastern Brazil for a hindcast of 1974‐1996 monthly streamflow. The ECHAM 4.5 and the NCEP/MRF9 GCMs and regional models, including dynamical and statistical models, are integrated with the ABCD and Soil Moisture Accounting Procedure water balance models. Precipitation hindcasts from the GCMs are downscaled via the regional models and fed into the water balance models, producing streamflow hindcasts. Multi‐model ensemble combination techniques include pooling, linear regression weighting, and a kernel density estimator to evaluate streamflow hindcasts; the latter technique exhibits superior skill compared with any single coupled model ensemble hindcast. 相似文献
718.
Hajkowicz S Spencer R Higgins A Marinoni O 《Journal of environmental management》2008,88(4):1601-1610
This study borrows concepts from healthcare economics and uses cost utility analysis (CUA) to select an optimum portfolio of water quality enhancement projects in Perth, Western Australia. In CUA, costs are handled via standard discounted cash flow analysis, but the benefits, being intangible, are measured with a utility score. Our novel methodology combines CUA with a binary combinatorial optimisation solver, known as a 'knapsack algorithm', to identify the optimum portfolio of projects. We show how water quality projects can be selected to maximise an aggregate utility score while not exceeding a budget constraint. Our CUA model applies compromise programming (CP) to measure utility over multiple attributes in different units. CUA is shown to provide a transparent and analytically robust method to maximise benefits from water quality remediation investments under a constrained budget. 相似文献
719.
Understanding the process of the changing phytoplankton patterns can be particularly useful in water quality improvement and management decisions. However, it is generally not easy to illustrate the interactions between phytoplankton biomass and related environmental variables given their high spatial and temporal heterogeneity. To elucidate relationships between them, in a eutrophic shallow lake, Taihu Lake, relative long-term data set of biotic and abiotic parameters of water quality in the lake were conducted using multivariate statistical analysis within seasonal periodicity. The results indicate that water temperature and total phosphorus (TP) played governing roles in phytoplankton dynamics in most seasons (i.e. temperature in winter, spring and summer; TP in spring, summer and autumn); COD (chemical oxygen demand) and BOD (biological oxygen demand) presented significant positive relationships with phytoplankton biomass in spring, summer and autumn. However, a complex interplay was found between phytoplankton biomass and nitrogen considering significant positive relationships occurring between them in spring and autumn, and conversely negative ones in summer. As the predatory factor, zooplankton presented significant grazing-pressure on phytoplankton biomass during summer in view of negative relationship between them in the season. Significant feedback effects of phytoplankton development were identified in summer and autumn in view that significant relationships were obser,qed between phytoplankton biomass and pH, Trans (transparency of water) and DO. The results indicate that interactions between phyto:plankton biomass and related environmental variables are highly sensitive to seasonal periodicity, which improves understanding of different roles of biotic and abiotic variables upon phytoplankton variability, and hence, advances management methods for eutrophic lakes. 相似文献
720.
基于对高职《旅游学概论》在教学中存在的诸多问题进行的分析,结合高职旅游专业学生的特点,对教学内容、教学方法、考核方式等几方面的改革和创新进行了阐述。 相似文献