Predicting regional space–time variation of PM2.5 with land-use regression model and MODIS data

Purpose  

Existing land-use regression (LUR) models use land use/cover, population, and traffic information to predict long-term intra-urban variation of air pollution. These models are limited to explaining spatial variation of air pollutants, and few of them are capable of addressing temporal variability. This article proposes a space–time LUR model at a regional scale by incorporating aerosol optical depth (AOD) data from the Moderate Resolution Imaging Spectroradiometer (MODIS).     

水质模型参数识别的遗传算法

Ｏ’ｃｏｎｎｏｒ模型是一个比广泛应用的Ｓｔｒｅｅｔｅｒ－Ｐｈｉｌｉｐｓ模型更精确的水质模型,由于该模型参数率定的困难性,限制它在实际中应用。     

Source apportionment of exposures to volatile organic compounds. I. Evaluation of receptor models using simulated exposure data

Four receptor-oriented source apportionment models were evaluated by applying them to simulated personal exposure data for select volatile organic compounds (VOCs) that were generated by Monte Carlo sampling from known source contributions and profiles. The exposure sources modeled are environmental tobacco smoke, paint emissions, cleaning and/or pesticide products, gasoline vapors, automobile exhaust, and wastewater treatment plant emissions. The receptor models analyzed are chemical mass balance, principal component analysis/absolute principal component scores, positive matrix factorization (PMF), and graphical ratio analysis for composition estimates/source apportionment by factors with explicit restriction, incorporated in the UNMIX model. All models identified only the major contributors to total exposure concentrations. PMF extracted factor profiles that most closely represented the major sources used to generate the simulated data. None of the models were able to distinguish between sources with similar chemical profiles. Sources that contributed <5% to the average total VOC exposure were not identified.     

Estimation of primary drainage three-phase relative permeability for organic liquid transport in the vadose zone

The modeling of transport of organic liquid contaminants through the vadose zone often requires three-phase relative permeabilities. Since these are difficult to measure, predictive models are usually used. The objective of this study is to assess the ability of eight common models to predict the drainage relative permeability to oil in a three-phase system (water-oil-air). A comparison of the models' estimates using data set from Oak [Oak, M.J., 1990. Three-phase relative permeability of water-wet Berea. In: Seventh Symposium on Enhanced Oil Recovery, Paper SPE/Doe 20183. Tulsa, OK, April 22-25] showed that they provide very different predictions for the same system. The goodness of the models does not increase with the amount of data or computation that the models require. Also, the calculations showed how different interpretations of the models and of the terminology associated with them can significantly impact the predictions. Thus, considerable error may be introduced into the simulations of organic liquid transport in the vadose zone depending on the selection and interpretation of the three-phase relative permeability model.     

A dynamic contaminant transport computational architecture (DCTCA) for radiological assessment of ecological systems

A novel methodology called dynamic contaminant transport computational architecture (DCTCA) is developed to help flexibility of constructing process structure for radiological assessment of ecological systems. The method tracks radionuclide movements in ecological systems by doing calculations on vectors and matrices. All environmental components in an ecosystem are both sources and receptors as they are media that pass radionuclides. The transport factor matrix is the transformation matrix from sources to receptors. The cubic transport model base (CTMB) in the architecture allows a number of transport models to be selected and applied to a single source-receptor transport process. CTMB stores those models in a cubic structure and has them available to be selected and form a combined model set to be used in scenarios.     

Application of agroforestry business models to tropical peatland restoration

Indonesia is home to around 45% of the world’s tropical peatlands which continue to be degraded on a large scale by deforestation, drainage and fire, contributing massively to global GHG emissions. Approaches to restoring the peat–water balance and reducing emissions in peat hydrological units, through managing them based either on full protection or large-scale commercial production, have generally failed to address environmental and local community needs. We present published and unpublished findings pointing to the need for an integrated peatland protection and restoration strategy based first on raising water levels in degraded (drained) peatlands and maintaining them in forested peatlands, thus, reducing GHG emissions. Second, the strategy incorporates ecologically sound agroforestry business models that strengthen livelihoods of smallholders and so sustain their interest in sustainably managing the peatlands. In this paper, we focus on the second element of this strategy in Indonesia. Eight agroforestry business models are proposed based on their merits to attract both smallholders and commercial investors as well as their compatibility with hydrological rehabilitation of the peatlands. While financial returns on investment will vary across sites and countries, our analysis indicates that some models can be profitable over both short and longer time periods with relatively low levels of investment risk.     

Assessment of uncertainties in a long range atmospheric transport model: Methodology, application and implications in a UK context

Acid deposition models are inherently simplified representations of real world behaviour and their performance is best evaluated by comparison with observations. National and international acid rain policy assessments handle observed and modelled deposition fields in different ways. Here, both the observed and modelled deposition fields are seen as uncertain and the Generalised Likelihood Uncertainty Estimation (GLUE) framework is used to choose acceptable sets of model input parameters that minimise the differences between them. These acceptable sets of model parameters are then used to estimate deposition budgets to the UK and to provide a probabilistic treatment of excess deposition over environmental quality standards (critical loads).     

Comparison of calculation models for wind-driven rain deposition on building facades

Wind-driven rain (WDR) is an important factor in the dry and wet deposition of atmospheric pollutants on building facades. In the past, different calculation models for WDR deposition on building facades have been developed and progressively improved. Today, the models that are most advanced and most frequently used are the semi-empirical model in the ISO Standard for WDR assessment (ISO), the semi-empirical model by Straube and Burnett (SB) and the CFD model by Choi. This paper compares the three models by applying them to four idealised buildings under steady-state conditions of wind and rain. In each case, the reference wind direction is perpendicular to the windward facade. For the CFD model, validation of wind-flow patterns and WDR deposition fluxes was performed in earlier studies. The CFD results are therefore considered as the reference case and the performance of the two semi-empirical models is evaluated by comparison with the CFD results based on two criteria: (1) ability to model the wind-blocking effect on the WDR coefficient; and (2) ability to model the variation of the WDR coefficient with horizontal rainfall intensity R_h. It is shown that both the ISO and SB model, as opposed to the CFD model, cannot reproduce the wind-blocking effect. The ISO model incorrectly provides WDR coefficients that are independent of R_h, while the SB model shows a dependency that is opposite to that by CFD. In addition, the SB model can provide very large overestimations of the WDR deposition fluxes at the top and side edges of buildings (up to more than a factor 5). The capabilities and deficiencies of the ISO and SB model, as identified in this paper, should be considered when applying these models for WDR deposition calculations. The results in this paper will be used for improvement and further development of these models.     

Proposals to overcome limitations in the EU chemical risk assessment scheme

The notification of new chemicals in the European Union requires a risk assessment. A Technical Guidance Document (TGD) was prepared for assistance. The TGD proposes QSARs, regressions and models from various sources. Each method has its own range of applicability and its own restrictions. Regressions used in the assessment of indirect human exposure have a common regression range from log K(OW), 3.0-4.6. Most models are compartment models, which do not consider a spatial distribution of the chemical, and were originally developed for non-dissociating, lipophilic persistent chemicals with measurable vapor pressure. Taking this into account, the TGD is only applicable for a minority of chemical classes. Dissociating compounds, ions, polar and very non-polar compounds do not belong to them. The effect of mixtures cannot be considered, except for hydrocarbons. Using the example of plant uptake, it is shown that in certain cases uptake is underestimated by the model due to processes not considered. This may lead to a wrong security in risk assessment. To overcome these limitations, a set of alternative models with different application ranges should be developed. When no applicable method is available, it might be better not to use a model at all instead of an inadequate model, and look for other sources of information.     

The Change of Concentration Standard Deviations with Distance

Calculations of pollutant concentrations at various downwind and crosswind distances from an elevated point source are frequently based on diffusion models and parameter values contained in Turner’s Workbook of Atmospheric Dispersion Estimates.1 These calculations can be made much more speedily on a computer or on a currentgeneration, programmable desk calculator, if the values of the horizontal and vertical standard deviations of plume concentrations distributions are stated explicitly as a mathematical function of downwind distance. The alternative is to read the values from Turner’s Figures 3-2 and 3-3 and input them into the calculation for each individual value of downwind distance.     

Developing conceptual frameworks for the recovery of aquatic biota from acidification

Surface water acidity is decreasing in large areas of Europe and North America in response to reductions in atmospheric S deposition, but the ecological responses to these water-quality improvements are uncertain. Biota are recovering in some lakes and rivers, as water quality improves, but they are not yet recovering in others. To make sense of these different responses, and to foster effective management of the acid rain problem, we need to understand 2 things: i) the sequence of ecological steps needed for biotic communities to recover; and ii) where and how to intervene in this process should recovery stall. Here our purpose is to develop conceptual frameworks to serve these 2 needs. In the first framework, the primarily ecological one, a decision tree highlights the sequence of processes necessary for ecological recovery, linking them with management tools and responses to bottlenecks in the process. These bottlenecks are inadequate water quality, an inadequate supply of colonists to permit establishment, and community-level impediments to recovery dynamics. A second, more management-oriented framework identifies where we can intervene to overcome these bottlenecks, and what research is needed to build the models to operationalize the framework. Our ability to assess the benefits of S emission reduction would be simplified if we had models to predict the rate and extent of ecological recovery from acidification. To build such models we must identify the ecological steps in the recovery process. The frameworks we present will advance us towards this goal.     

Description of sorbing tracers transport in fractured media using the lattice model approach

The transport of contaminants in fractured media is a complex phenomenon with a great environmental impact. It has been described with several models, most of them based on complex partial differential equations, that are difficult to apply when equilibrium and nonequilibrium dynamics are considered in complex boundaries. With the aim of overcoming this limitation, a combination of two lattice Bathnagar, Gross and Krook (BGK) models, derived from the lattice Boltzmann model, is proposed in this paper. The fractured medium is assumed to be a single fissure in a porous rock matrix. The proposed approach permits us to deal with two processes with different length scales: advection-dispersion in the fissure and diffusion within the rock matrix. In addition to the mentioned phenomena, sorption reactions are also considered. The combined model has been tested using the experimental breakthrough curves obtained by Garnier et al. (Garnier, J.M., Crampon, N., Préaux, C., Porel, G., Vreulx, M., 1985. Tra?age par 13C, 2H, I- et uranine dans la nappe de la craie sénonienne en écoulement radial convergent (Béthune, France). J. Hidrol. 78, 379-392.) giving acceptable results. A study on the influence of the lattice BGK models parameters controlling sorption and matrix diffusion on the breakthrough curves shape is included.     

Addressing uncertainty in environmental modelling: a case study of integrated assessment of strategies to combat long-range transboundary air pollution

Model development and testing tend to concentrate on how well models represent “reality” or reproduce measurements. However, there are many sources of uncertainty in modelling atmospheric pollution, and those responsible for decisions on abatement strategies need to use modelled scenarios without fear that inaccuracies and assumptions in the modelling may mislead them. This paper explores how techniques from risk assessment may be used to examine a modelling study systematically. Those assumptions and uncertainties which could have significant consequences, whether arising from data used, the modelling itself, or factors omitted and incompleteness, may be identified using hazard and operability studies. This helps to target supporting studies—possibly using more complex models, or Monte Carlo uncertainty analysis; and to indicate potential implications to the decision makers. As a case study we have used work undertaken on uncertainties with the Abatement Strategies Assessment Model for the task force on integrated assessment modelling under the convention on long-range transboundary air pollution of the UN Economic Commission for Europe.     

环境中的邻苯二甲酸酯

本文较为系统地评述了邻苯二甲酸酯的环境行为、生态效应、环境归趋、数学模型和处理技术。指出邻苯二甲酸酯是生产量大和应用面广的人工合成有机化学品,是目前世界上全球性的一类环境有机污染物。这类化合物的低水溶度和低挥发性导致了它们的高吸附亲和性,从而使得该类化合物在固体颗粒物表面的行为对于研究它们在环境中各种过程具有十分重要的作用。     

大气超细颗粒物观测和扩散模拟研究进展

总结了近年来不同地区对不同环境下大气超细颗粒物的观测和扩散模拟研究进展。大量的观测研究结果表明,大气超细颗粒物的时空分布、组成特征、形成和成长的特性因观测地区的不同而存在很大差异,受气象因素和局部污染源的影响很大;其来源主要包括固定、移动燃烧源的直接排放和大气中颗粒成核现象,前一种来源一般是局部的,而后一种来源则是区域性的。目前,大多数关于大气超细颗粒物扩散的模拟研究都是针对其质量浓度的,对其数浓度扩散的模拟研究主要集中在小范围(机动车排放烟云的研究方面),在城市区域范围上的研究和应用还很少。最后,探讨和展望了大气超细颗粒物今后的主要研究方向和研究中面临的挑战。     

Description of sorbing tracers transport in fractured media using the lattice model approach

The transport of contaminants in fractured media is a complex phenomenon with a great environmental impact. It has been described with several models, most of them based on complex partial differential equations, that are difficult to apply when equilibrium and nonequilibrium dynamics are considered in complex boundaries. With the aim of overcoming this limitation, a combination of two lattice Bathnagar, Gross and Krook (BGK) models, derived from the lattice Boltzmann model, is proposed in this paper. The fractured medium is assumed to be a single fissure in a porous rock matrix. The proposed approach permits us to deal with two processes with different length scales: advection–dispersion in the fissure and diffusion within the rock matrix. In addition to the mentioned phenomena, sorption reactions are also considered. The combined model has been tested using the experimental breakthrough curves obtained by Garnier et al. (Garnier, J.M., Crampon, N., Préaux, C., Porel, G., Vreulx, M., 1985. Traçage par ¹³C, ²H, I⁻ et uranine dans la nappe de la craie sénonienne en écoulement radial convergent (Béthune, France). J. Hidrol. 78, 379–392.) giving acceptable results. A study on the influence of the lattice BGK models parameters controlling sorption and matrix diffusion on the breakthrough curves shape is included.     

Absorption of nitro-polycyclic aromatic hydrocarbons by biomembrane models: effect of the medium lipophilicity

To demonstrate the relationship between the structure of nitro-polycyclic aromatic hydrocarbons and their effect on biomembranes, we have investigated the influence of three structurally different nitro-polycyclic aromatic hydrocarbons, 2-nitrofluorene, 2,7-dinitrofluorene and 3-nitrofluoranthene, on the thermotropic behavior of dimyristoylphosphatidylcholine multilamellar vesicles, used as biomembrane models, by means of differential scanning calorimetry. The obtained results indicate that the studied nitro-polycyclic aromatic hydrocarbons affected the thermotropic behavior of multilamellar vesicles to various extents, modifying the pretransition and the main phase transition peaks and shifting them to lower temperatures. The effect of the aqueous and lipophilic medium on the absorption process of these compounds by the biomembrane models has been also investigated revealing that the process is hindered by the aqueous medium but strongly allowed by the lipophilic medium.     

Influence of solid waste and topography on urban floods: The case of Mexico City

Floods in cities are increasingly common as a consequence of multifactor watershed dynamics, including geomorphology, land-use changes and land subsidence. However, urban managers have focused on infrastructure to address floods by reducing blocked sewage infrastructure, without significant success. Using Mexico City as a case study, we generated a spatial flood risk model with geomorphology and anthropogenic variables. The results helped contrast the implications of different public policies in land use and waste disposal, and correlating them with flood hazards. Waste disposal was only related to small floods. 58% of the city has a high risk of experiencing small floods, and 24% of the city has a risk for large floods. Half of the population with the lowest income is located in the high-risk areas for large floods. These models are easy to build, generate fast results and are able to help to flood policies, by understanding flood interactions in urban areas within the watershed.     

Adherence of Sulfur Dioxide Concentrations in the Vicinity of a Steam Plant to Plume Dispersion Models

Air monitoring data for a calendar year at one of the TVA power plants has been used to evaluate the appropriateness of the Sutton, the Bosanquet and Pearson, and the USPHS-TVA atmospheric dispersion models to predict ground level concentrations of sulfur dioxide from emission and meterological data. Aerometric data included one half hourly average sulfur dioxide concentrations, recorded by four Thomas autometers, and the necessary meterological parameters for the solving of atmospheric dispersion models. Based on these meterological parameters and observed plume rise data, over 4000 one half hourly average maximum and minimum expected ground line sulfur dioxide concentrations were predicted for each of the above dispersion models by the use of computer techniques. The plant is a line source; however, an empirical correction was applied to emission data to reduce them to emissions for an equivalent point source. The predicted sulfur dioxide levels for each of the dispersion models were compared to the measured levels throughout the year. Three different sets of diffusion coefficients were applied to the Sutton model and successful predictions, according to a criterion utilizing an acceptable range of concentration, varied from 66 to 93%. The Bosanquet and Pearson model produced successful predictions 90% of the time, while the USPHS-TVA model was successful 94% of the time.Unsuccessful predictions were primarily overestimates.     

Three-dimensional quantitative structure activity relationship (3D-QSAR) analysis for in vitro toxicity of chlorophenols to HepG2 cells

In the present paper, comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were applied to investigate two 3D-QSAR models for the cytotoxicity of chlorophenols. These models have evaluated the intensity of chlorophenols' toxicity on HepG2 cells in vitro. The CoMFA model has both high consistency and predictability. The contribution of the electrostatic field to biological activity is greater than that of the steric field. The CoMSIA model used in this study includes two fields, one is hydrophobic field, and the other is electrostatic field. The relative contribution of them is 0.789:0.211. Consisted with the CoMFA model, the CoMSIA electrostatic filed also plays a dominant role. The CoMFA and CoMSIA contour maps significantly elucidated that the electrostatic field is more important than the other fields and might be one of the reasons resulting in potential reactive mechanism involved in cell proliferation inhibition.