四明湖水库浮游植物功能类群的季节演替及其影响因子

浮游植物群落变化既受到环境因子单独作用的影响,也受到各因子之间交互作用的影响.为探究浮游植物群落结构的季节演替规律,对四明湖水库浮游植物群落及水体11项非生物因子和4项生物因子进行周年采样调查,分析了水库内浮游植物功能类群组成、季节演替规律及其与生物因子和非生物因子的关系.结果显示,调查期间四明湖水库的浮游植物种类可归入22个功能类群,其优势功能类群主要隶属于绿藻门和硅藻门.非度量多维尺度分析(NMDS)显示,浮游植物群落结构呈现出明显的季节性演替;通过SIMPER分析,筛选出10个与季节变化显著相关的功能类群,其主要变化过程表现为:夏季D+Lo→秋冬季D+P+Lo→春季X2+P+MP.方差分解分析(VPA)显示,浮游植物功能类群的季节变化是由水温-浮游动物交互作用与水温单独作用共同影响的结果;典范对应分析(CCA)发现,水温(WT)、透明度(SD)和硝态氮(NO-3-N)以及浮游动物生物量是影响该水库浮游植物群落结构动态变化的主要因子.     

Meteorological mechanism for a large-scale persistent severe ozone pollution event over eastern China in 2017

An intensive and persistent regional ozone pollution event occurred over eastern China from 25 June to 5 July 2017.73 out of 96 selected cities,most located in the Beijing-TianjinHebei and the surrounding area(BTHS),suffered severe ozone pollution.A north-south contrast ozone distribution,with higher ozone(199±33 μg/m~3) in the BTHS and lower ozone(118±25 μg/m~3) in the Yangtze River Delta(YRD),was found to be dominated by the position of the West Pacific Subtropical High(WPSH) and mid-high latitude wave activities.In the BTHS,the positive anomalies of geopotential height at 500 hPa and temperature at the surface indicated favorable meteorological conditions for local ozone formation.Prevailing northwesterly winds in the mid-high troposphere and warm advection induced by weak southerly winds in the low troposphere resulted in low-moderate relative humidity(RH),less total cloud cover(TGC),strong solar radiation and high temperatures.Moreover,southerly winds prevailing over the BTHS aggravated the pollution due to regional transportation of O_3 and its precursors.On one hand,the deep sinking motion and inversion layer suppressed the dispersion of pollutants.On the other hand,O_3-rich air in the upper layer was maintained at night due to temperature inversion,which facilitated O_3 vertical transport to the surface in the next-day morning due to elevated convection.Generally,temperature,UV radiation,and RH showed good correlations with O_3 in the BTHS,with rates of 8.51(μg/m~3)/℃(within the temperature range of 20-38℃),59.54(μg/m~3)/(MJ/m~2)and-1.93 μg/m~3)/%,respectively.     

基于天气分型的上甸子大气本底站臭氧污染气象条件

对流层臭氧作为典型二次污染物已成为北京春夏季首要污染物,气象因素是影响其浓度变化的主要因子之一.本研究基于2008~2017年大气成分和气象观测数据,利用Lamb-Jenkinson天气分型法结合Mann-Whitney U检验方法将影响北京地区天气型分为6类,其中SWW和C型上甸子臭氧浓度均值和极值分别最高,在4~9月出现频率最高,合计出现47.4%,并通过多元逐步回归方程确定两种型的主要贡献权重.SWW和C型下54%盛行西南风,新排放的污染物和二次老化气团经西南气流持续输送,850 hPa附近出现垂直速度零层,水平和垂直气象条件均有利于臭氧的输送、生成和聚积;AN和ESN型下64.7%盛行东北风或北风,气团来源清洁,1000 hPa以上盛行一致的下沉运动和气流辐散,新排放的污染物也能很快被稀释扩散,臭氧浓度处于较低值.以NW型2015年5月3日为例,虽然地面盛行西北气流,来源清洁,但大气通过垂直下沉运动将边界层以上的高浓度残留臭氧向近地面输送,导致某些天数中出现臭氧浓度高值.     

艾比湖流域典型植物生长的水文地质条件研究

在野外实际调查资料基础上,总结了艾比湖流域典型植物胡杨、梭梭、红柳赋存的地貌位置、当前主要存在问题、适生地下水位埋深、包气带岩性与结构等水文地质条件,为流域的综合治理提供依据。     

Surface Ozone Concentrations and its Relation to Wind Field in Istanbul

In this study, an assessment has been made on the wind speed; temperature and atmospheric pressure were analyzed by considering meteorological variables for selected high ozone cases. The Systems Applications International Meso-scale Model (SAIMM), a prognostic meteorological model was used to develop the 3-dimensional meteorological inputs to a chemical model. Meteorological conditions favorable for high ozone concentrations appear when Istanbul and the surrounding region is dominated by an anticyclonic pressure system. During the ozone favorabledays, south and southwesterly winds with low wind speed influence Istanbul. We presented wind field simulations for a case study in explaining the ozone formation mechanism over Istanbul.     

因地制宜的开展退耕还林工程建设

本文深入分析了当前新疆自然生态环境存在的问题及严峻形势，阐述了在新疆实施退耕还林(草)工程的重要意义。改善新疆的生态环境，走良性循环的持续发展道路，应从过去的失误中总结经验教训，尊重科学，师法自然，因地制宜，科学合理地确定退耕还林(草)规模。以政策保证退耕还林(草)工程的顺利实施，从根本上改善干早区的生态环境。通过退耕还林(草)工程的实施，调整种养产业结构，使新疆逐步走出“粮化、沙化、贫困化”的怪圈，“退”出一条脱贫致富的发展之路和一片秀美山川。     

APPLICATIONS OF A STEADY-STATE,ONE-DIMENSIONAL WATER QUALITY MODEL1

ABSTRACT: A steady-state, one-dimensional water quality model has been formulated to evaluate spatial variations of Biochemical Oxygen Demand, ammonia nitrogen, and dissolved oxygen for nontidal, branched river systems, with point sources of treated wastes and uniform nonpoint-source loads, under aerobic and/or anaerobic stream conditions. For anaerobic conditions, the decay rate of organic matter is assumed to be limited by the rate of oxygen addition to the streams via stream reaeration and net algal photosynthesis and respiration contributions. The model is applicable to stream impact analysis under sustained wet weather conditions, during which storm-runoff loads are generated by storms of sufficiently long duration to approach steady state in the river system.     

黑龙江省发展循环经济的条件分析

循环经济是指遵循生态规律,按照减量化、再利用、资源化的原则,采取经济、技术和管理等措施,实现资源高效利用和减少废物排放的活动,是符合可持续发展理念的经济发展模式.文章从黑龙江省实际情况出发,从黑龙江省的基础条件和循环经济发展潜力两个方面分析了发展循环经济的有利条件;从认识、机制、政策、技术等五方面分析了发展循环经济的制约因素;从而为黑龙江省发展循环经济提出行之有效的措施,充分地发挥黑龙江省的资源优势,做到可持续发展.     

Did you say reference conditions? Ecological and socio-economic perspectives on the European Water Framework Directive

Reference conditions are a key concept in the European Water Framework Directive (WFD). The WFD stipulates that the ecological status of a given water body shall be assessed by quantifying the deviation from a set of reference conditions that represent the stable state of an ecosystem in the absence of significant human disturbance. This concept is subject to criticism from several authors, particularly because underlying ecological concepts are weak and the distinction between natural variability and the effects of anthropogenic activities on ecosystem function will become increasingly artificial. In this paper, a sociologist and an aquatic ecologist examine the origin, successes and limits of the reference conditions concept and raise important questions about applying this concept in practice. We argue that this concept fitted specific needs from different institutions and stakeholders which promoted the WFD. Monitoring practices using this concept require some adaptations. Setting goals for restoration based on reference conditions is more problematic. A more adaptive management approach would be wiser.     

长江三角洲冬季一次低能见度过程的地区差异和气象条件

采用NCEP再分析资料、MICAPS地面、高空气象资料以及国家环保部空气质量监测资料,对2014年2月20~22日长江三角洲地区一次低能见度过程地区差异和气象条件进行了分析.天气形势分析表明,长三角地面处在高压的控制下,地面风速较小,使污染物积累,有利于低能见度(雾-霾)的形成和维持.根据不同区域的雾、霾分布和日变化特征,将长江三角洲地区分为3个子区域:I区为江苏大部(雾霾混合型),II区为上海及其周边(霾类型),III区为浙江大部(雾类型),该区域白天能见度较高,夜间能见度较低的特征是由湿度因子造成的.影响I区能见度变化的主要原因是:热力原因:大气对流层低层的层结稳定;湿度原因为:空气较湿润,气溶胶粒子吸湿性增长;动力原因主要是垂直方向和水平方向的大气扩散能力弱;污染因子对能见度变化的影响较小.影响II区能见度变化的主要原因是PM2.5浓度高导致的污染,热力因子、湿度因子和动力因子对能见度的变化影响很小.影响III区能见度变化的热力原因是:大气对流层低层层结稳定、近地面存在逆温;湿度原因是因为:空气较湿润,气溶胶粒子吸湿性增长;动力原因是因为边界层高度较低导致的垂直扩散能力较差.各个区域的气象因子解释方差的计算结果表明:I区湿度因子和动力因子对能见度的影响更大,III区.湿度因子对能见度的影响更大.