Application of CFD Methods for Modelling in Air Pollution Problems: Possibilities and Gaps

Different urban air pollution problems deal with complex structure of air flows and turbulence. For such problems the Computer Fluid Dynamics (CFD) methods become widely used. However, this approach despite a number of advantages has some problems. Experience of use of CFD tools for development of models and suggestions of their applications for a local scale air pollution over a complex terrain and stable stratification are discussed in this paper, including: Topography and complex geometry: choose of the co-ordinate system and computer grid; Turbulence closure for air pollution modelling: modified k- model for stable stratified ABL; Boundary conditions for vertical profiles of velocity for stable-stratified atmosphere; Effects of the radiation and thermal budget of inclined surfaces to dispersion of pollutants; Artificial sources of air dynamics and circulation.Some examples of CFD applications for air pollution modelling for a flat terrain, mountainous area, mining open cast and indoor ventilation are discussed. Modified k- model for stably-stratified ABL is suggested. Due to the isotropic character of the k- model a combination of it in vertical with the sub-grid turbulence closure in horizontal can be more suitable for ABL. An effective scheme of boundary conditions for velocity profiles, based on the developed similarity theory for stable-stratified ABL, is suggested. Alongside with the common studies of atmospheric dispersion, the CFD methods have also demonstrated a good potential for studying anthropogenic and artificial-ventilation sources of air dynamic and circulation in local-scale processes of air pollution.     

Effect of temperature on single and competitive adsorptions of Cu(II) and Zn(II) onto natural clays

This study conducted a combined adsorption-sequential extractionanalysis (CASA), by which five phases (i.e., exchangeable, carbonate, Mn-Oxide, organic, and Fe-Oxide phases) of adsorbed heavy metals were analyzed, to investigate temperature effects on single and competitive adsorptions of Zn(II) and Cu(II) ontonatural clays. In the case of single adsorption of Zn, the exchangeable phase adsorption decreased from 65 to 40%, but thecarbonate phase adsorption increased from 30 to 40%, with an increase in temperature from 15 to 55 °C. However, in itscompetitive adsorption with Cu, Zn was mostly present in the exchangeable phase (over 90%), and with an increase in temperature, the exchangeable phase adsorption decreased only 10%. In the case of Cu, over 50% among the total amount of adsorption was present in the carbonate phase in both cases ofsingle and competitive adsorptions. The carbonate phaseadsorption of Cu increased from 56 to 61% and from 60 to 66% in single and competitive adsorptions, respectively, with atemperature increase. These results show that in the case of Zn,the major mechanism of retention in natural clay soils might beexchangeable phase adsorption, especially in the case of competitive adsorption with Cu. However, in the case of Cu, the major mechanism might be carbonate phase adsorption, which is known to be a more immobile phase than exchangeable phase adsorption. It seems that the adsorption of Zn and Cu onto natural clays is an endothermic reaction, which represents thatthe adsorption equilibrium constants and capacities increase with a temperature increase, with the exception of exchangeablephase adsorption.     

Atrazine and Alachlor Inputs to Surface and Ground Waters in Irrigated Corn Cultivation Areas of Castilla-Leon Region, Spain

The inputs of atrazine and alachlor herbicides to surface and ground waters from irrigated areas dedicated to corn cultivation in the Castilla-León (C-L) region (Spain) as related to the application of both herbicides were studied. Enzyme-linked immunosorbent assays (ELISA) were used for monitoring the atrazine and alachlor concentrations in 98 water samples taken from these areas. Seventy-nine of the samples were of ground waters and 19 were of surface waters. The concentration ranges of the herbicides detected in the study period (October 1997–October 1998) were 0.04–25.3 g L^–1 in the surface waters and 0.04–3.45 g L^–1 in the ground waters for atrazine, and 0.06–31.9 g L^–1 in the surface waters and 0.05–4.85 g L^–1 in the ground waters in the case of alachlor. The highly significant correlation observed between the concentrations of both herbicides in the surface waters (r = 0.89, p < 0.001) pointed to a parallel transport of atrazine and alachlor to these waters. A study was made of the temporal evolution of the concentrations of both herbicides, and it was found a maximum recharge of atrazine in the ground waters for April 1998 and of alachlor in October 1997 and October 1998. The temporal evolution of the concentrations of both herbicides in surface waters was parallel. The highly significant correlations observed between atrazine concentrations determined by ELISA and by HPLC (r = 0.92, p < 0.001) and between alachlor concentrations also determined by both methods (r = 0.96, p < 0.001) confirmed the usefulness of ELISA for monitoring both herbicides in an elevated number of samples. Using HPLC, the presence in some waters of the alachlor ethanesulfonate (ESA) metabolite was found at a concentration range of 0.52–4.01 g L^–1. However the interference of ESA in the determination of alachlor by ELISA was negligible. The inputs of atrazine and alachlor to waters found in this study, especially the inputs to ground waters, could pose a risk for human health considering that some waters, though sporadically, are even used for human consumption.     

Geostatistical Uncertainty Modelling for the Environmental Hazard Assessment During Single Erosive Rainstorm Events

This paper presents an environmental hazard assessment to account the impacts of single rainstorm variability on river-torrential landscape identified as potentially vulnerable mainly to erosional soil degradation processes. An algorithm for the characterisation of this impact, called Erosive Hazard Index (EHI), is developed with a less expensive methodology. In EHI modelling, we assume that the river-torrential system has adapted to the natural hydrological regime, and a sudden fluctuation in this regime, especially those exceeding thresholds for an acceptable range of flexibility, may have disastrous consequences for the mountain environment. The hazard analysis links key rainstorm energy variables expressed as a single-storm erosion index (EI_sto), with impact thresholds identified using an intensity pattern model. Afterwards, the conditional probabilities of exceeding these thresholds are spatially assessed using non-parametric geostatistical techinques, known as indicator kriging. The approach was applied to a test site in river-torrential landscape of the Southern Italy (Benevento province) for 13 November 1997 rainstorm event.     

灰色系统模型在总悬浮物预测中的应用

以１９８６－１９９４年东北某城市总悬浮物统计资料为依据，应用灰色系统理论ＧＭ（１，１）模型对总量浮物数值进行预测分析。     

我国内陆流域各类水体中天然放射性核素浓度

1985年～1989年由新疆、甘肃、青海、西藏、内蒙古、陕西、宁夏等省、自治区环境监测站(研究所)对内陆流域各类水体中U、Th、~(226)Ra、~(40)K浓度进行调查,由调查的29条内陆河、23个湖泊、15座水库、55处井泉和34个自来水的统计结果表明,流域内各水体中U和~(40)K浓度的平均值与同期调查的黄河水系同类水体的浓度相近,明显高于长江水系,与全国同类水体相比亦属偏高。Th和~(226)Ra的平均浓度与全国同类水体的浓度相近,甘、新内陆区浓度较低。调查发现,一些咸水湖、井水和自来水中U、~(226)Ra,或~(40)K浓度异常偏高。     

Fractionation of Cu, Pb and Zn in certified reference soils SRM 2710 and SRM 2711 using the optimized BCR sequential extraction procedure

Sequential extraction of metals from solid media is a common analytical tool used in environmental and exploration geochemistry. A number of procedures exist, but without harmonization and standardization, meaningful comparisons are tenuous without baseline data. A newly developed, standardized sequential extraction procedure (optimized BCR) was applied to two contaminated certified reference soils from Montana, US (SRM 2710 and SRM 2711) for Cu, Pb and Zn. Four operationally defined fractions were isolated, acid extractable, reducible, oxidizable, and residual (by aqua regia). Fraction-specific concentrations, percentages and recoveries for Cu, Pb and Zn were used to explore differences between the optimized BCR procedure and three other sequential extraction schemes with published data for SRM 2710 and 2711 (i.e. Tessier scheme, Geological Survey of Canada scheme and the original BCR scheme). Results indicate significant differences between the four schemes, even for schemes that are closely associated (i.e. the original and optimized BCR schemes). Order-of-magnitude fraction-specific concentration differences were observed, especially for Pb in the reducible fraction. Differences between schemes are worrisome because trends varied between metals, between fractions and between reference soils. These data reinforce the need for increased adoption of standardized sequential extraction procedures and further examination of different solid media.     

有机磷酸酯诱导迟发性神经毒性及其对神经毒性酯酶（NTE）活性影响的动态研究

以成年产卵来航母鸡为试验动物，研究了三甲基苯基磷酸酯（Ｔｒｉ－ｏ－ＣｒｅｓｙｌＰｈｏｓ－ｐｈａｔｅ，ＴＯＣＰ）诱导的迟发性神经毒性．试验发现，母鸡口服ＴＯＣＰ（７５０ｍｇ／ｋｇ）后，经过大约８－１０ｄ的潜伏期开始出现中毒症状，其表现为以步态失调为主要特征的运动障碍呈进行性加重，至第２１ｄ开始便发展为瘫痪，对鸡脑神经病损靶标酯酶（ＮｅｕｒｏｐａｔｈｙＴａｒｇｅｔＥｎｚｙｍｅ，ＮＴＥ）活性的测定表明，有机械诱导的迟发性神经毒性（Ｏｒｇａｎｏｐｈｏｓｐｈａｔｅ－ＩｎｄｕｃｅｄＤｅｌａｙｅｄＰｏｌｙｎｅｕｒｏｐａｔｈｙ，ＯＰＩＤＰ）与ＮＴＥ活性抑制之间的关系不平行，其毒性症状的轻重与ＮＴＥ活性被抑制的强弱也不呈正相关，很可能，在给药后２４ｈ，体内ＯＰＩＤＰ已被触发，此外，实验观察到给予ＴＯＣＰ后被试鸡的体重明显下降。     

三维虚拟地理环境构建与应用

可量测三维虚拟地理环境是数字地球应用的基础平台。本文研究了三维虚拟地理环境构建空间几何建模与纹理建模关键技术。提出了一种适用于大规模生产建库的可量测三维虚拟地理环境构建的生产工艺模型和三维虚拟模型数据获取的方法。介绍了三维虚拟地理环境在城市规划、房产经营管理等方面的应用。     

中国黄土元素背景值分异规律研究

报道了中国黄土中40个元素的背景值,并以F、Cr、Mn、Co、Ni、V、Cu、Zn、As、Se、Cd、Pb、Hg等13个元素为例,讨论了其在黄土高原的分布与含量。利用趋势面分析等数理统计方法,揭示了黄土中元素的某些环境地球化学特征及元素背景值的分异规律。结果表明,黄土的元素背景值具有三维的分异特征,黄土的质地及沉积的生物气候环境黄土是影响背景值分异的主要因素。为中国黄土的风成学说提供了佐证。