POTENTIAL OF EPISODIC FLOWS IN SOME FOUR REPRESENTATIVE NON-PERENNIAL RIVER FLOW CATCHMENTS IN SEMI ARID LAIKIPIA DISTRICT, KENYA

The purpose of this study was to establish the water resources of thenon-perennial streams in providing supplementary water needs inLaikipia district. This district has undergone remarkable land usechanges resulting in water use stress of perennial river abstractions andgroundwater exploitation in the semi arid environment.Over a three year period extending from January 1989 to December1991, hydrological variables were monitored in four non-perennial flowcatchments within the district. These catchments have been shown tohave potential of about 8000 m³/km²/year except forlong dry spells during the observation period and high sediment lossesand evaporation rates calling for proper conservation measures in orderto exploit productively the water resources potential of such catchments.     

Monitoring Long-Term Ecological Changes Through the Ecological Monitoring and Assessment Network: Science-Based and Policy Relevant

Ecological monitoring and its associated research programshave often provided answers to various environmental management issues. In the face of changing environmental conditions, ecological monitoring provides decision-makers with reliable information as they grapple with maintaining a sustainable economy and healthy environment. The EcologicalMonitoring and Assessment Network (EMAN) is a national ecological monitoring network consisting of (1) about 100 casestudy sites across the country characterized by long-term multi-disciplinary environmental work conducted by a multitudeof agencies (142 partners and counting); (2) a variety of lesscomprehensive yet more extensive monitoring sites; (3) a network where core monitoring variables of ecosystem change aremeasured; and (4) geo-referenced environmental observations. Environment Canada is the co-ordinating partner for the network through the EMAN Co-ordinating Office. EMAN's mission is to focus a scientifically-sound, policy-relevant ecosystem monitoring and research network based on (a) stabilizing a network of case-study sites operated by a varietyof partners, and (b) developing a number of cooperative dispersedmonitoring initiatives in order to deliver unique and needed goods and services. These goods and services include: (1) an efficient and cost-effective early warning system which detects,describes and reports on changes in Canadian ecosystems at a national or ecozone scale; and (2) cross-disciplinary and cross-jurisdictional assessments of ecosystem status, trends and processes. The early warning system and assessments of ecosystem status, trends and processes provide Environment Canada and partner organizations with timely information thatfacilitates increasingly adaptive policies and priority setting. Canadians are also informed of changes and trends occurring in Canadian ecosystems and, as a result, are betterable to make decisions related to conservation and sustainability.     

nZVI@mesoSiO2的可控合成及应用性能研究

采用改进的两步法在原位基础上合成了以纳米零价铁(nano Zero Valent Iron,nZVI)为核芯的核壳型介孔二氧化硅(nZVI@mesoSiO_2).同时,通过简单地调控铁源用量得到具有单一nZVI核芯和不同壳层厚度的核壳型纳米复合材料.结果发现,铁源用量的增加会导致核芯尺寸减小、壳层厚度增加及颗粒比表面积下降.当铁源用量为2.78 g时,得到的nZVI@mesoSiO_2不仅具有较高的比表面积和单一且均匀的孔径分布,而且对2,4,6-三氯苯酚(2,4,6-Trichlorophenol, 2,4,6-TCP)的去除表现出很高的性能.影响因素实验表明,材料的最佳投加量为1.0 g·L~(-1),体系适宜初始pH为5.0,污染物初始浓度升高会导致去除效果下降,并且反应体系内乙二胺四乙酸(EDTA)的存在可以提高2,4,6-TCP的去除率.材料的重复利用实验结果表明,经过多次循环反应后会导致材料nZVI核芯的失活和孔道的堵塞.本研究不仅为制备可控壳层厚度的核壳型介孔材料提供了理论指导,而且为进一步改性合成对2,4,6-TP具有高选择性的复合材料提供了依据.     

重庆市都市功能核心区秋季大气污染物时空分布特征

为研究重庆市都市功能核心区大气污染物浓度水平及变化规律,统计分析了2014年9月至2014年11月5个监测站(解放碑、高家花园、杨家坪、新山村和南坪)24 h连续监测PM_(2.5)、PM_(10)、SO_2、NO_2、CO和O_3浓度数据.结果表明,观测期间,大气颗粒物污染严重,5个站点PM2.5日均浓度超标率分别为30.8%、37.4%、38.5%、37.4%和31.9%,5个站点PM10日均浓度超标率分别为23.1%、22.0%、18.7%、19.8%和19.8%;重庆市都市功能核心区细颗粒物(PM_(2.5))污染严重,5个站点PM2.5占PM10比例分别为60.2%、64.6%、64.1%、75.4%和62.8%;PM_(2.5)、PM_(10)、NO_2和CO早晚出现高峰值;SO_2和O_3浓度日变化曲线呈现单峰型,峰值分别出现在中午和午后;降水量、气温和水汽压与PM_(2.5)、PM_(10)、SO_2和NO_2呈显著负相关;相对湿度与O_3呈显著负相关,气温、水汽压和风速与O_3呈显著正相关;CO与相对湿度呈显著正相关;风向也影响着大气污染物浓度的时空分布,南偏西、南偏东和东北偏北风利于PM_(2.5)、PM_(10)、SO_2、NO_2和CO浓度积累,西北风利于PM_(2.5)、PM_(10)、SO_2、NO_2和CO扩散;但西北风控制下利于O_3浓度积累.     

THE IMPACT OF POLICY VARIABLES ON RESIDENTIAL WATER DEMAND AND RELATED INVESTMENT REQUIREMENTS1

Increasing population and urbanization necessitate very large investments in municipal water supply. These investments could be more efficiently deployed if the impact of policy variables such as marginal pricing, metering, by-laws on lawn watering and plumbing fixtures, and higher summer charges were known. The paper in particular advocates the replacement of the present declining block rate by an increasing block rate. In order to know the impact of policy variables, a multiple regression model is built; the fitted model is tested against some data not included in calibrating the model. Next the impact of selected policy variables on the target variable (residential water demand during summer) is worked out for a new urban community of 200,000 people. The investment requirements may decrease appreciably as a result of a price increase when marginal (or commodity) charges are low but the impact of price changes when commodity charges are already high is less evident and non-price policy variables may be more effective in maintaining high quality water and also satisfying the constraint of limited budgets for municipal services.     

带压作业闸板防喷器胶芯失效机理研究

针对带压作业过程中闸板防喷器胶芯易失效的问题,以现场使用的带压作业闸板防喷器胶芯为研究对象,通过实验确定了橡胶基体的本构关系,利用ABAQUS软件对比研究了4种不同井筒压力对胶芯的疲劳失效与密封失效的影响。结果表明:分析结果与现场应用胶芯的失效位置相符,验证了分析的正确性;胶芯的疲劳失效位置集中在橡胶基体与闸板上下部的4个尖角接触区域,上部区域失效严重;井筒压力的大小影响橡胶基体密封面上的接触应力分布,但对耐磨块密封面上接触应力分布影响不显著。建议在橡胶基体与闸板上下部的4个尖角区域补强以增加胶芯寿命。     

A stochastic fuzzy chance-constrained programming model for energy–environment system planning and management in the City of Beijing

A stochastic and fuzzy chance-constrained programming (SFCCP) model was developed in this study for supporting energy–environment management in the city of Beijing, China. SFCCP was capable of tackling the variables in constraints as fuzzy random variables, which were integration of randomness and vagueness. SFCCP was applied to an energy–environment management system in the city of Beijing. The study results indicated that SFCCP was useful in helping decision makers gain in-depth insights into proposed management system and establish environment-friendly energy allocation alternatives. The application of SFCCP is expected to provide a good demonstration to energy–environment management problems under complex uncertainties.     

Sedimentary record of PAHs in the Liangtan River and its relation to socioeconomic development of Chongqing, Southwest China

Concentrations of polycyclic aromatic hydrocarbons (PAHs) were detected in sediment cores and surface sediment samples from the Liangtan River of Chongqing, Southwest China. The total concentration of 16 PAHs ranged from 69 to 6251 ng g⁻¹. The spatial distribution of the PAHs reflects the intensity and scope of human activity in the catchment. A historical record of PAH contamination was reconstructed using a sediment core from a background segment of the river. The characteristic changes of concentrations, fluxes and patterns of 16 PAHs over the past ∼90 years were captured in detail. An obvious peak of PAH concentration and flux was found in the 1940s, i.e., during war time, and then a sharp increase was observed from the early 1980s to the present. The maximum concentration and flux reached 1260 ng g⁻¹ and 470 ng cm⁻² year⁻¹, respectively. The sharp increase was attributed to the contribution of pyrogenic sources of PAHs. The population, length of highways and energy consumption of Chongqing, as indexes of socioeconomic development, were positively correlated with PAH input in the sediment core from the 1950s to the present. The results clearly show that the local socioeconomic development in the last decades remarkably aggravated the environmental load of sedimentary PAHs.     

VA菌根真菌对玉米生长及根际土壤微生态环境的影响

用两种不同的VA菌根真菌Glomus mosseae和Glomuscaledonium接种玉米进行盆栽试验。结果表明,两种菌株均能侵染玉米,促进玉米生长．其中以Glomus caledonium的侵染率和作用较为明显。接种后,根区土壤中的细菌、放线菌、固氮菌的数量和微生物生物量明显增加,但真菌的数量则稍有下降。此外．菌根的形成也改善了根区土壤的微生态环境,为下一造作物的生长积累了养分基础。     

泉州湾沉积物柱状样中有机氯农药的垂直分布特征

用GC-ECD内标法测定了泉州湾沉积物柱样中有机氯农药的含量.通过研究有机氯农药在沉积物柱样中的垂直分布特征,探讨了有机氯农药在泉州湾的污染历史.该柱样中HCHs和DDTs的含量分别为(0.00～5.61)×10-9、(1.18～50.65)×10-9.研究表明该区沉积物未受到HCHs的明显污染,但已受到DDTs的轻微污染.有机氯农药的垂直变化基本反映了它在我国及福建的生产使用历史.在近年泉州湾仍有新的DDT输入.