北京市北运河流域属于典型缺水型城市纳污河流,沉积物释放的氮磷污染物已成为阻碍水环境质量持续改善的主要因素.利用自制环形水槽,对不同流速下沉积物中氮磷的动态释放规律进行研究,结果表明,静态条件下,沉积物中氨氮平均释放速率1136 mg/(m2·d),磷酸盐平均释放速率为145 mg/(m2·d),在流速0.05 m/s的缓流水体中,氨氮平均释放速率为1408 mg/(m2·d),而磷酸盐平均释放速率为125 mg/(m2·d).流速增加会显著促进氮素的硝化作用,使水体中氨氮浓度降低,硝酸盐氮浓度上升.同时,流速增加导致水体中颗粒物含量增加,促进磷吸附行为,水体中磷酸盐浓度下降.

基于MIKE11模型构建了北运河干流（北京段）一维河流水动力、水质模型。以2010年为基准年,综合考虑"十二五"期间人口增长、经济发展及农业规模和布局情况,设置3套减排方案。选择北京市榆林庄断面为主控监测断面,以氨氮低于5mg/L、COD低于40mg/L为水质控制目标,开展不同减排措施效果评估。结果表明,污水处理厂提标改造是改善北运河流域（北京段）水质的最有效手段,能使榆林庄断面COD和氨氮相比2010年分别下降27.2%、60.6%,COD达到水质控制目标。氨氮减排难度较大,除了实施污水处理厂提标改造外,应同步提高综合排放标准,使氨氮排放相对2010年下降73.5%,达到水质控制目标。同时,还应加强对城市暴雨径流污染的控制,以有效降低前汛期水体污染物峰值浓度。

Comprehensive degradation coefficient is one of the key parameters of water quality simulation prediction and water environment capacity calculation, which is influenced by temperature. First, based on 2010 daily temperature of the North Canal in Beijing and the empirical formula which describes the relationship between the amount of ammonia degradation coefficient and temperature, the dynamic degradation coefficient fluctuated by temperature and the constant degradation coefficient corresponding to annual average temperature were obtained, which were corrected by using trial and error method. Then, the ammonia concentration fluctuation of YulinZhuang section in Beijing was simulated based on MIKE11 on the scenarios of the dynamic degradation coefficient and the constant degradation coefficient. The results showed that the annual trend of ammonia concentration could be simulated well on both scenarios, but monthly average concentration error of most months were relatively low compared to the measured value under the dynamic degradation coefficient, especially from April to December the Model was more stable, and the monthly average concentration error could be controlled under 15%, and the annual average simulation error was less than 4%.

Models-3/CMAQ modeling system was used to simulate the spatial and temporal distribution of PM2.5 pollution over Beijing during APEC, 2014(i.e. November 3 to 11, 2014). IPR, a process analysis tool embedded in CMAQ, was employed to quantify the contributions of different atmospheric processes to the PM2.5 formation at two typical sites (i.e. Guanyuan and Dingling) during two short-time pollution processes (i.e. Nov. 4 13:00 to Nov. 5 12:00 and Nov. 10 13:00 to Nov. 11 12:00). The results showed that CMAQ reproduced the temporal variation and magnitude of PM2.5 reasonably. Adverse synoptic system occurred on Nov. 4 and Nov. 10, resulting in two peak values of PM2.5 (188μg/m3 and 124μg/m3). Elevated PM2.5 levels didn't last long because of the pollution control measures and the cold anticyclone. During Nov. 4 13:00 to Nov. 5 12:00, horizontal transport was the primary contributor to the PM2.5 at both Guanyuan and Dingling, with a contribution rate of 49.6% and 90.9%, respectively, indicating that Beijing was mainly affected by pollution transported from southern areas. During Nov. 10 13:00 to Nov. 11 12:00, PM2.5 at Guanyuan site mainly came from local emission (78.8%), while PM2.5 at Dingling site mainly came from relatively weak horizontal transport, demonstrating a local pollution characteristic. Vertical transport played a dominative role in the decrease of PM2.5 in both pollution processes.

污染排放信息是环境决策的重要依据.分析了北京市水环境质量的现状,基于最新源排放清单,解析北京市当前主控污染物COD、氨氮排放的结构特征和空间特征,以期为北京市开展基于流域综合治理的水污染控制和水环境管理提供依据.按照工业源、农业源、生活源和集中处理设施的环境统计口径,2013年,COD、氨氮的排放构成分别为2.7％、37.1％、35.0％、25.3％和1.5％、20.1％、54.8％、23.6％.其中,农业源中畜禽养殖排放是主要来源,COD、氨氮总排放分别占农业源总排放量的94.7％和87.0％.在北京市五大水系中,北运河流域排放量最大,COD、氨氮排放量分别占全市总排放量的53.3％和57.4％.为改善北京市水环境质量,建议从加快污水处理厂提标改造、推动面源污染治理、加强水利联通、合理规划城市规模布局等4个方面入手.

2014年2月19—27日,北京出现了重度污染及以上水平的霾天气,严重危害着人们的身体健康。以北京该段持续污染过程为研究对象,基于同期气象数据与PM_（2.5）观测数据,利用SPSS统计软件分析了PM_（2.5）浓度与气象因子间的相关性,探究区域周边城市PM_（2.5）污染变化特征及其与地面天气形势之间的关系。研究结果表明,在一定的气象条件下,PM_（2.5）浓度与风速、相对湿度分别呈显著的负相关、正相关,与气压呈负相关,与气温无显著相关关系。同时,比较该时段北京市与周边区域7个城市的PM_（2.5）浓度变化趋势及后向轨迹分析,发现北京市与周边城市在相似的气象背景条件下,污染过程具有区域性特征。华北地区处于地面高压均压场控制时,地面风速小,逆温层明显,大气层结稳定,区域扩散条件差,弱偏南气流主导时间长,受局地源积累和区域输送的影响,污染物浓度累积上升,可形成持续霾天气。

Hydraulic engineering group refers to a complex water supply system, consisting of water conser-vancy projects, water diversion projects, water lifting projects, inter-basin water transfer projects as well as sluice and dam projects.It has been accepted to be a key support to deal with regional droughts.Given that the expres-sion of drought coping ability is not uniform and the current quantitative evaluation methods need to be improved, the connotation of drought coping ability of hydraulic engineering projects has been defined firstly.Then the drought coping ability index of hydraulic engineering group ( HEGdca ) was defined from the perspective of both essence of drought and the forming mechanism of drought disaster.Finally, a quantitative evaluation method of drought coping ability of hydraulic engineering projects has been put forward based on the HEGdca .Taking 2010 as the level year for evaluation, the HEGdca under given project condition has been calculated for different drought scenarios in the study area.The result shows that when taking the average water deficient ratio as the criteria for evaluation, the current (2010) hydraulic engineering projects in the Zhangwei River basin can effectively resist a meteorological drought event with less than 30-year return period on the whole.The result of quantitative evaluation is generally consistent with the actual situation of the study area, which can offer a technological support for drought planning and the risk management of drought disaster.

In January 2013, Beijing area experienced several severe haze weather events. The pollution of fine particles has become an important problem in Beijing. Understanding the sources of PM2.5 in Beijing is essential for solutions and related policy-formulations. Three-dimensional air quality modelling system was established to analyze the PM2.5 pollution during 20-24 January in 2013. PSAT technology was used to study the regional sources of Beijing PM2.5 pollution. The results showed that local emission was the major source of PM2.5 in Beijing City, with an average contribution rate of 34% . The average contribution rates of Hebei and Tianjin were 26% and 4%, respectively. The neighboring area and the boundary conditions contributed 12% and 24% to PM2.5 in Beijing. In the heavy pollution period, the influence of regional transportation increased significantly, and became the major source of PM2.5 pollution in Beijing. Nitrate in PM2.5 in Beijing mainly came from the surrounding area of Beijing City, while sulfate and secondary organic aerosols showed characteristics of long-distance transportation. Ammonium salt and other components were mainly from Beijing local contribution.

随着"十一五"总量减排工作的深入开展,我国的环境统计制度受到前所未有的挑战,如何将污染源的污染物排放量核定准确,已成为环境统计工作的瓶颈;此外,基层环境统计工作缺乏监督、不受重视等问题也直接影响着环境统计的数据质量.本文通过对我国环境统计制度内容和方法的分析,总结了目前环境统计制度中存在的一些问题,并结合国内外的环境统计经验,提出了解决问题的方法.

Rock is a kind of transformable Porous Medium.With the action of loads on rock,the creep occurs.Some physics parameters,such as porosity and permeability,vary along with creep.Meanwhile,the changing physics parameters influence the stress field and velocity field,which can determine creep capability of the rock.In this paper,a special seepage is studied,in which creep is taken into account.According to correspondence principle,a group of novel dynamics stress balancing equations,which including creep parameters,is developed.Based on it,a mathematical model of flow in porous medium on account of solid-fluid coupling and creep effect is derived.