Total variation diminishing schemes for pollutant transport in porous media     

Lahcen Zouhri  Hassan Smaoui  Erick Carlier 《水文研究》2008,22(5):651-659

A bidimensional numerical model has been used in order to simulate the contaminant transport in the coastal groundwater area (Atlantic margin of the Rharb basin, Morocco). This groundwater is materialized by means of the salt contamination derived from several factors: evapotranspiration, lithological series formations, marine intrusion, and processes of interaction between water and rocks. In order to reduce the numerical diffusion and limit the numerical dispersion, we use the Superbee flux limiter as a total variation diminishing scheme to discretize the convective operator. This kind of discretization was applied to the coastal groundwater of the Rharb basin (Morocco). The results show that the Superbee flux limiter is efficient at drawing the path of the contaminant front with high accuracy. Consequently, this scheme could constitute an approach in water management and allows one to prevent the risks of pollution and to manage the groundwater resource from a durable development perspective. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Pollution history of the savannah river estuary and comparisons with Baltic Sea pollution history     

C. Alexander  R. Smith  B. Loganathan  J. Ertel  H.L. Windom  R.F. Lee   《Limnologica》1999,29(3):267

The sediment record, as revealed in sediment cores, can be used to reconstruct the history of contaminant input into estuaries. The basic assumptions are that contaminant inputs equilibrate relatively rapidly with sediment inputs and that the sediment column represents a continuous sequence of sediment and associated contaminant accumulation. With radiochemical chronologies, it is possible to date sediments over a period corresponding to about five half-lives (100 years for ²¹⁰Pb). In our study we reconstruct the pollution history of the Savannah Estuary, which is a typical estuary in the South Atlantic Bight. A series of cores were taken in the estuary, followed by the analysis of the cores for a variety of organic and inorganic contaminants. Ages were assigned to different depth intervals by the use of two radiotracers, ²¹⁰Pb and ¹³⁷Cs. The major pesticides found were an isomer of DDT and dieldrin. The peak in their concentrations (1967) correlated with peak use of these pesticides before their use was banned. Between 1959 and 1962, there was more input of anthropogenic PAHs than before and after this period. The metals which showed significant changes in the cores include mercury, lead and chromium. Chromium reached a maximum during the late 1950s, followed by a decrease in the late 1960s. This chromium peak coincided with the initial operation of a titanium dioxide pigment plant in the Savannah Estuary. An interesting aspect of the study, which has been noted by many pollution history studies, was the decrease in the concentration of anthropogenic chemicals during the past two decades, suggesting that pollution controls have been effective, even while industrial and population growth was taking place.Similar studies have been carried out to reconstruct the historical record of contamination in the Baltic Sea. Concentrations of metals were found to increase after 1880 (industrial revolution in northern Europe). PCBs peaked in concentration in the late 1960s and the early 1970s, while DDT peaked in the 1960s. The Baltic experienced a major input of nutrients (N and P) after 1965 resulting from heavy use of fertilizers in this region.  相似文献   

Natural and Enhanced Concentrations of Trace Metals in Sediments of Cleveland Bay, Great Barrier Reef Lagoon, Australia   总被引：1，自引：0，他引：1  

G.B Doherty  G.J Brunskill  M.J Ridd 《Marine pollution bulletin》2000,41(7-12):337-344

Natural variation in concentrations of Cd, Co, Cu, Ni, Pb, and Zn in sediments of Cleveland Bay can be modelled by linear regression by using the concentration of Al recovered by strong acid digestion as an independent variable. Samples that exceed the upper 95% prediction interval of regression models are classified as enhanced. Enhancement of trace metals occurs in the intertidal zone and near-shore sediments of western Cleveland Bay, in sites that are characterized by high accumulation rates of fine grained terrigenous sediment. There is a strong positive relationship between increasing enhancement of Cu and Pb and the recovery of these metals by weak HCl digestion, which suggests that for these metals the modelled enhancement is environmentally meaningful. In contrast, at least 60%, and generally greater than 80% of Cd is recovered by weak HCl digestion irrespective of modelled enhancement, and suggests that the statistically modelled enhancement of Cd may be more meaningful than weak HCl soluble concentrations.  相似文献   

全球应对气候变化的合作新模式——探析“气候变化三方合作”     

左佳鹭  张磊  陈敏鹏 《气候变化研究进展》2021,17(1):98-106

三方合作是与传统的南南合作和南北合作模式互补的国际合作新模式。由于具有可充分调动多方资源、发达国家和新兴捐助国的互补效应强、形式灵活等优势,三方合作目前得到了越来越多国家和国际组织的关注和参与。2016年全球已有838个三方合作项目,经济发展与合作组织(OECD)发展援助委员会成员的2/3都在不同程度地参与三方合作项目,其中德国、日本、西班牙和美国参与的项目最多。新兴捐助国中参与三方合作项目最多的国家是智利和墨西哥。目前三方合作项目执行期较短、项目额度小,29%的项目提到了绿色目标。目前虽然气候变化三方合作的案例还不多,但是截至2018年底32个发展中国家和5个发达国家都提出要开展气候变化三方合作的兴趣。由于起步较晚,气候变化三方合作目前面临着资金不足、沟通协调过程复杂、合作成本高等问题。中国应积极探索气候变化三方合作,推动不同部门南南合作、三方合作和其他多边双边合作的资源统筹,并应增强项目管理的规范性,提高项目效果和影响。  相似文献   

济南市区泉域地下水时空分布规律及污染物运移特性研究     

何奔  贾超  刘新宇  孙嘉瞞  张国荣 《工程地质学报》2014,22(5):981-988

泉水作为济南市的城市名片,具有重要的经济和社会价值,把握泉域内突发污染质泄漏对其产生的影响至关重要。本文概化建立了济南市的水文地质概念模型,利用地下水非稳定流数值模型对济南市区泉群附近范围的地下水进行了分析研究,得到了济南市区泉域内地下水的时空分布规律及污染物运移特性。在此基础上,分析某新建项目污染质泄漏对地下水环境产生的影响,通过设置不同的横纵向弥散度对污染物运移特性进行探究。结果表明,在泉群附近区域内,污染物纵向运移过程中对流起主要作用,纵向弥散度的取值影响较小; 而污染物横向运移过程中弥散起主要作用,横向弥散度的取值影响较大。本研究成果对泉群附近的地下水环境保护及地下水污染防控具有重要借鉴意义。  相似文献   

城市褐色土地识别的方法与实践     

林明水  李家兵  谢红彬 《世界地理研究》2013,(3):169-176

褐色土地识别是其再开发的前提和基础。作者梳理国内外关于褐色土地定义,在此基础上界定褐色土地识别的概念,参考国外识别的经验并结合中国国情,制定褐色土地识别的框架和流程,并以福州市为例,选取2011年福州市国土资源局公开出让的35宗地块,实践城市褐色土地识别。通过第一阶段将地块原土地利用活动对照《重点污染源行业分类》标准进行筛选,选出疑似污染地块进行第二阶段环境污染信息收集和采样分析进行褐色土地识别,将褐色土地分为三类。结果显示：编号为03、04等25宗地块没有污染,识别为褐色土地类型Ⅰ;其余的疑似污染地块中,宗地编号为02、05等8地块,虽存在污染物,但污染物浓度低于标准值,识别为褐色土地类型Ⅱ;宗地编号为01、25地块的部分污染物浓度值超过标准值,需进行修复后才能再利用,识别为褐色土地类型Ⅲ。  相似文献   

欧美地下水有机污染调查评价进展   总被引：5，自引：0，他引：5  

刘菲  王苏明  陈鸿汉 《地质通报》2010,29(5):907-917

1999年中国地质调查局启动了第一个地下水有机污染调查项目,当时检测指标只有20个(包括11个挥发性有机污染物、8种有机氯农药和1种多环芳烃)。“十一五”的地下水有机污染调查必测项目包含了38项(挥发性指标28项、有机氯农药9项和1种多环芳烃),取得了地下水有机污染的基本资料。但从对国外文献的调研来看,地下水中有机污染的种类远远超过38种。为了更全面地掌握中国地下水的质量,有必要对不同地区或不同类型的地下水中典型的有机污染物的种类进行研究,为后续地下水有机污染调查的增项做准备。通过检索美国环保局(USEPA)、美国地质调查局(USGS)和欧盟(EU)近年来的地下水质量年度报告和相关文献,调研了地下水中典型有机污染物的类型,选出最常检出的有机污染物,形成最常检出的有机污染物的检出率排序表,列出了检出率高的前50个污染物的名单。  相似文献   

1966年3月24日耀斑的分析研究     

印春霖  唐玉华 《天文学报》1996,37(2):181-186,T001

本文用数据方法分析了紫金山天文台色球望远镜观测的１９９６年３月２４日３Ｂ级双带主资料，结果表明：由于新浮磁流改变背景磁场，光球剪切运动引起暗条圆柱轴向磁力线扭转而使暗条电流增加，致使暗条整体力学平衡破坏，驱动暗条向上运动。并对暗条上升运动与耀斑爆发的物理关系进行了分析讨论。  相似文献   

Geochemistry of organic contaminants in Narragansett Bay sediments     

Richard J. Pruell  James G. Quinn 《Estuarine, Coastal and Shelf Science》1985,21(3):295-312

Organic contaminants from several different chemical classes were analyzed in surface sediments along a transect from the head to the mouth of Narragansett Bay. The chemical classes included total hydrocarbons, polycyclic aromatic hydrocarbons, substituted benzotriazoles and phthalic acid esters. Sediment concentrations of all compounds were highest in the Providence River and decreased with distance downbay. The observed decreases were approximately exponential for all compounds; however, the distances at which the concentrations decreased to one-half of their initial concentrations (half-distances) were different.The depth distributions of these compounds in sediment cores from three locations were also investigated. A sediment core collected near the head of the bay (Conimicut Point) showed a well defined historical record of contaminant input to the bay. At a mid-bay location (North Jamestown), however, the record was smeared because of extensive bioturbation.A sediment core collected near the mouth of the bay (Rhode Island Sound) showed a subsurface increase for all of the measured compounds. The results of detailed analyses suggest that this horizon may have been influenced by dredge spoil material originally from the head of the bay.  相似文献   

地下水的有机污染问题及其吸附作用评价     

谢秀辉  王洪涛 《地球科学与环境学报》1989,(2)

文章认为有机污染质已对地下水污染构成威胁,研究有机污染质在地下水系统中的迁移转化机制,建立有效的预测模型,具有十分重要的意义。有机污染质与地下水形成不溶混流体,对其运移进行评价的理论、方法及测试技术都不同于通常对易溶混污染质的评价。这项工作在我国刚刚起步,研究程度较低。文章讨论了有机污染质—地下水体系的一般物理、化学特征和运移控制方程,指出吸附作用是使有机污染质运移滞缓的重要原因,介绍了目前国外研究有机污染质吸附作用的几种试验及结果。  相似文献