Kinematic wave solutions for pollutant transport over an infiltrating plane with finite‐period mixing and mixing zone     

V. P. Singh 《水文研究》2002,16(12):2441-2477

Kinematic wave solutions are derived for transport of a conservative non‐point‐source pollutant during a rainfall‐runoff event over an infiltrating plane for two cases: (i) finite‐period mixing and (ii) soil‐mixing zone. Rainfall is assumed to be steady, uniform and finite in duration, and it is assumed to have zero concentration of pollutants. Infiltration is assumed constant in time and space. Prior to the start of rainfall, the pollutant is distributed uniformly over the plane. In the first case, when rainfall occurs, the mixing of pollutant in the runoff water occurs in a finite period of time. In the second case, the chemical concentration is assumed to be a linearly decreasing function of rainfall intensity and overland flow. The solute concentration and discharge are found to depend on the flow characteristics as well as the solute concentration parameters. The characteristics of solute concentration and discharge graphs seem to be similar to those reported in the literature and observed in laboratory experiments. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

THE CHARACTERISTIC OF MARINE ENVIRONMENT IN LINGDINGYANG ESTUARY     

CHEN Bing-lu  ZHANG Yun-ni  CHEN Xin-geng  WANG Zhi-gang  YANG Guang-xing 《中国地理科学(英文版)》2001,11(2):155-162

1 HYDROLOGIC FEATURES Lingdingyang Estuary, located at the middle south of Guangdong Province, is a bell-shaped estuary with a north-south direction. Its area is about 2100km2. The north of Qi′ao Island and Inner-Lingding Island, and the south of Humen are grouped as Neilingdingyang Estuary, having an area of 1041km2. Affected by topography, runoff and tide, its dynamic condition is very complicated. Different water areas have different hydrologic features. The topography under …  相似文献   

新疆库尔勒市空气质量等级及首要污染物时空变化研究     

巩庆  范金霞  林卫 《沙漠与绿洲气象(新疆气象)》2017,11(5):77-82

城市空气质量与经济建设及人民生活息息相关,是政府和人民关注的重大社会问题。利用库尔勒市2014年9月1日-2015年8月31日州政府、棉纺厂、开发区三个环境监测站逐时观测资料,分析了库尔勒市空气质量等级和首要污染物的时空分布,并分析了污染天气发生的日变化特征。结果表明：（1）三站污染天气出现频率分别为49.4%、40.9%和34.7%,符合州政府＞棉纺厂＞开发区的分布规律。三站污染天气均是春季出现频率最高,分别占到44.7%,39.4%和48.5%,其次为秋季、冬季和夏季;（2）库尔勒市首要污染物中, PM10的频率最高,其次为PM2.5,CO、NO2、O3及SO2出现频率均低于10.0%。PM10作为首要污染物在春季出现频率最高,三站出现频率为33.9%-36.3%,PM2.5则是冬季出现频率最高,三站出现频率为59.1%-86.4%;（3）库尔勒市污染天气和重污染天气发生频率符合傍晚与夜间高,白天低的变化规律。污染天气发生频率最高值出现在0:00时,最低值出现在6:00-7:00时,重污染天时延迟到9:00时。上述结果表明库尔勒市春季周边自然污染源的排放与输送对该市的空气质量影响巨大。  相似文献   

A microscale model for air pollutant dispersion simulation in urban areas: Presentation of the model and performance over a single building   总被引：1，自引：0，他引：1  

Ning Zhang  Yunsong Du  Shiguang Miao 《大气科学进展》2016,33(2):184-192

A microscale air pollutant dispersion model system is developed for emergency response purposes. The model includes a diagnostic wind field model to simulate the wind field and a random-walk air pollutant dispersion model to simulate the pollutant concentration through consideration of the influence of urban buildings. Numerical experiments are designed to evaluate the model's performance, using CEDVAL(Compilation of Experimental Data for Validation of Microscale Dispersion Models) wind tunnel experiment data, including wind fields and air pollutant dispersion around a single building. The results show that the wind model can reproduce the vortexes triggered by urban buildings and the dispersion model simulates the pollutant concentration around buildings well. Typically, the simulation errors come from the determination of the key zones around a building or building cluster. This model has the potential for multiple applications; for example, the prediction of air pollutant dispersion and the evaluation of environmental impacts in emergency situations; urban planning scenarios;and the assessment of microscale air quality in urban areas.  相似文献   

江苏盐城地区一次持续雾-霾天气过程的综合分析   总被引：7，自引：3，他引：4  

周文君  平海波  刘端阳  魏建苏  韦莹莹  王群 《气象》2016,42(7):838-846

2013年12月上旬江苏盐城地区出现了一次历史罕见的持续重度雾-霾天气,利用盐城市常规气象观测资料、NCEP再分析资料(1°×1°)及环境监测中心站的污染物浓度资料等,对此次过程的环流背景、气象要素、大气层结特征以及动力条件、污染情况等进行了综合性分析。结果发现:12月上旬中高层冷空气势力弱,以纬向环流为主;低层弱的水平风场为雾-霾的发生发展提供了有利的环流背景;稳定的层结特征,近地面高强度的贴地逆温和持续较低的混合层高度是此次雾-霾天气长时间维持的重要因素;边界层内弱正散度及负涡度是此次雾-霾天气得以维持发展的动力因子;通过后向轨迹分型和火点监测资料分析发现:污染物的长距离输送在此次重污染天气的形成过程中起到了一定作用。最后,文中建立了能见度和PM_(2.5)浓度、相对湿度的非线性回归方程,对能见度的预报效果较好,为实际业务应用中雾-霾的预报提供了有利的依据。  相似文献   

无锡梅雨期湿沉降综合分析   总被引：2，自引：0，他引：2  

苏艳  刘端阳  彭华青  周彬  赵兵 《气象科学》2016,36(4):547-555

利用2008—2014年梅雨期间酸雨观测资料及2014年6月16—27日降水个例加密采样资料,结合大气污染物资料分析了近7 a无锡梅雨期酸雨特征,研究降水过程中空气污染物、p H值、电导率的变化及降水对污染物的清除作用。结果表明:无锡市梅雨期酸雨年平均p H值呈现逐年递增趋势。降水过程中,颗粒物质量浓度显著降低;气体浓度变化受其自身日变化及排放源影响大于雨水的清除作用;样品的p H值、K值每个过程变化并不一致,K值变化与颗粒物质量浓度变化大致保持一致。降水、风对颗粒物质量浓度影响大于对气体浓度的影响。长时间连续降水时,降水对颗粒污染物的清除存在极限。小时雨量在0~0.5 mm时,降水对颗粒物浓度做负清除,其值反而略有增加;小时雨量在0.6~5.0 mm时,降水对颗粒物质量浓度做正清除;小时雨量达到5.1 mm及以上时,对PM_(2.5)和PM_(2.5-10)做正清除,对PM_(10)做负清除。降水对SO_2有稀释清除作用;对NO_2的稀释作用取决于其开始浓度值;对CO、O_3的清除作用不显著。  相似文献   

The impact of physical processes on pollutant transport in Hangzhou Bay     

李宁  毛志华  张庆河 《中国海洋湖沼学报》2009,27(2):266-276

A Lagrangian tracer model is set up for Hangzhou Bay based on Coupled Hydrodynamical Ecological model for Regional Shelf Sea (COHERENS). The study area is divided into eight subdomains to identify the dominant physical processes, and the studied periods are March (the dry season) and July (the wet season). The model performance has been first verified by sea-surface elevation and tidal current observations at several stations. Eight tracer experiments are designed and Lagrangian particle tracking is simulated to examine the impact of physical processes (tide, wind and river runoff) on the transport of passive tracer released within the surface layer. Numerical simulations and analysis indicate that: (1) wind does not change the tracer distribution after 30 days except for those released from the south area of the bay during the wet season; (2) the tide and the Qiantang River runoff are important for particle transport in the head area of the bay; (3) the Changjiang River runoff affects the tracer transport at the mouth of the bay, and its impact is smaller in the dry season than in the wet season. Supported by the Natural Science Foundation of China (No.40576080); National High Technology Research and Development Program of China (863 Program, No. 2007AA12Z182)  相似文献   

Microplastics as contaminants in the marine environment: a review   总被引：15，自引：0，他引：15  

Cole M  Lindeque P  Halsband C  Galloway TS 《Marine pollution bulletin》2011,62(12):2588-2597

Since the mass production of plastics began in the 1940s, microplastic contamination of the marine environment has been a growing problem. Here, a review of the literature has been conducted with the following objectives: (1) to summarise the properties, nomenclature and sources of microplastics; (2) to discuss the routes by which microplastics enter the marine environment; (3) to evaluate the methods by which microplastics are detected in the marine environment; (4) to assess spatial and temporal trends of microplastic abundance; and (5) to discuss the environmental impact of microplastics. Microplastics are both abundant and widespread within the marine environment, found in their highest concentrations along coastlines and within mid-ocean gyres. Ingestion of microplastics has been demonstrated in a range of marine organisms, a process which may facilitate the transfer of chemical additives or hydrophobic waterborne pollutants to biota. We conclude by highlighting key future research areas for scientists and policymakers.  相似文献   

Content of mercury in leaves of Spartina alterniflora Loisel. in Georgia,U.S.A.: an update     

S.Y. Newell  R.E. Hicks  M. Nicora 《Estuarine, Coastal and Shelf Science》1982,14(4):465-469

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遥感图像中云层遮挡影响消除方法研究述评   总被引：4，自引：2，他引：4  

陈姚  王金亮  李石华 《国土资源遥感》2006,17(1):61-65

 综合评述了目前用于消除遥感图像云层遮挡影响方法的原理、应用现状及处理过程中存在的问题，并在同一实验区比较了同态滤波和Kriging插值等方法的处理效果，结果表明，Kriging插值处理具有一定的优越性。  相似文献