铜及其与四环素的联合暴露对斑马鱼胚胎的毒性效应

近年来工业和养殖业中铜和四环素的滥用,导致了一定程度的水环境污染问题。为探究铜与四环素对水生生物的毒害作用,选择斑马鱼作为受试生物,研究了铜及其与四环素的联合暴露对斑马鱼胚胎的毒性效应,并进一步探索了其中可能的致毒机制。结果表明:铜在低浓度下(10%致死浓度LC10=2.5μg·L~(-1),10%效应浓度EC_(10)=0.1μg·L~(-1))明显延迟了斑马鱼胚胎的孵化、卵黄囊吸收、头部、鱼鳔和体长等生长指标的发育,同时在心脏区域引起了明显的细胞凋亡效应。幼鱼体内总铜含量检测结果显示低浓度下铜的生物利用度相对更高。基因表达结果显示环境浓度的铜可能通过影响神经和心脏相关基因的表达引起斑马鱼胚胎的神经发育和心脏发育异常。铜和四环素的联合暴露实验结果表明二者的复合污染类型为拮抗作用,且两者相互作用可以形成络合物。综合以上结论,说明环境浓度的铜可能通过细胞凋亡、分子水平的变化等方式对水生生物的早期生长发育产生危害,如延迟生长发育、神经及心脏发育异常,另外铜可通过和四环素等环境中其他污染物的结合改变铜的生物有效性和毒性。     

Foodgrain disposals as early warning famine signals: A case from Burkina Faso*

Recent research suggests that monitoring key events in social, economic, cultural and political systems may provide more timely, frequent, and reliable warnings of impending famine than monitoring physical processes alone. But empirical data on early warning distress signals in these arenas are slim. Based on anthropological investigations in a southern Volta Noire community of Burkina Faso (formerly Upper Volta) during the drought of 1983–1984, this paper outlines a variety of possible early warning signals in disposal systems for staple foodgrains - the nutritional “bottom line” for farmers and herders in the West African savannah. Pre-famine distress signals in five broad categories are discussed: changes in marketing patterns, non-market exchanges, dietary practices, utilization of agricultural and pastoral labour, and ideological and sociopolitical behaviours. Data consist of both quantitative and qualitative comparisons of cereal disposals in these categories between 1983 and preceding years.     

RESEARCH: Optimizing the Mix of Strategies for Control of Vehicular Emissions

/ A number of strategies for the control of vehicular emissions are being considered by the Philippine government to address Metropolitan Manila's air quality problem. An analytical tool is needed for optimizing criteria pollutant reductions given the budgetary constraints. The simplest approach is to take costs and pollutant removals to be linear with each strategy's scale of activity, and this is readily solved as a linear programming problem. Another approach is to use a dynamic system of weights which shift with progressive improvements in pollutant emissions. The two approaches yield somewhat different results, suggesting the sensitivity of the solution to the assumed weights. The study also illustrates the importance of a sound methodology for evaluating priorities given to different air quality goals. One such methodology may involve a polling of expert panels and the public to gain insight into the relative importance given to competing emissions reduction goals. An informal polling of resource agency staff was conducted and discussed in this paper. The authors take the position that proper planning involves tracing intermediate steps to the final outcome and not just focusing on the latter.KEY WORDS: Vehicular emissions; Urban air quality; Emissions control; Optimization; Manila; Environmental systems analysis     

电力系统的污闪问题及防护

重点介绍了有关防污闪机理,深入研究并探讨了四种防污闪的常用技术和方法,分析了绝缘子从积污、湿润到闪络的详细过程,并通过附盐密度法绘制了盐密与闪络电压的关系,为防污闪工作提供理论指导。     

Global Warming and Global Dioxide Emission: An Empirical Study

In this paper, the dynamic relationship between global surface temperature (global warming) and global carbon dioxide emission (CO₂) is modelled and analyzed by causality and spectral analysis in the time domain and frequency domain, respectively. Historical data of global CO₂emission and global surface temperature anomalies over 129 years from 1860–1988 are used in this study. The causal relationship between the two phenomena is first examined using the Sim and Granger causality test in the time domain after the data series are filtered by ARIMA models. The Granger causal relationship is further scrutinized and confirmed by cross-spectral and multichannel spectral analysis in the frequency domain. The evidence found from both analyses proves that there is a positive causal relationship between the two variables. The time domain analysis suggests that Granger causality exists between global surface temperature and global CO₂emission. Further, CO₂emission causes the change in temperature. The conclusions are further confirmed by the frequency domain analysis, which indicates that the increase in CO₂emission causes climate warming because a high coherence exists between the two variables. Furthermore, it is proved that climate changes happen after an increase in CO₂emission, which confirms that the increase in CO₂emission does cause global warming.     

Environmental aftermath of the radiation accident at Tomsk-7

An analysis is presented of the environmental effects of the most serious radiation accident recorded after Chernobyl, which occurred in the formerly secret town of Tomsk-7 in Siberia, Russia, on 6, April 1993. Fortunately, it appears not to have become a major industrial crisis or disaster. The causes of the accident are described. It is argued that a mixture of both objective and subjective prerequisites, including specific human, organizational, and technological factors, were responsible for the explosion or directly facilitated it. The Tomsk-7 accident's ecological, medical, social, and psychological consequences are discussed.     

An Aquifer Classification System and Geographical Information System-Based Analysis Tool for Watershed Managers in the Western U.S.1

Payne, Scott M. and William W. Woessner, 2010. An Aquifer Classification System and Geographical Information System-Based Analysis Tool for Watershed Managers in the Western U.S. Journal of the American Water Resources Association (JAWRA) 46(5):1003-1023. DOI: 10.1111/j.1752-1688.2010.00472.x Abstract: Aquifers and groundwater systems can be classified using a variety of independent methods to characterize geologic and hydraulic properties, the degree of connection with surface water, and geochemical conditions. In light of a growing global demand for water, an approach for classifying groundwater systems at the watershed scale is needed. A comprehensive classification system is proposed that combines recognized methods and new approaches. The purpose of classification is to provide groundwater professionals, policy makers, and watershed managers with a widely applicable and repeatable system that reduces sometimes cumbersome complex databases and analyzes to straightforward terminology and graphical representations. The proposed classification system uses basin geology, aquifer productivity, water quality, and the degree of groundwater/surface water connection as classification criteria. The approach is based on literature values, reference databases, and fundamental hydrologic and hydrogeologic principles. The proposed classification system treats dataset completeness as a variable and includes a tiered assessment protocol that depends on the quality and quantity of data. In addition, it assembles and catalogs groundwater information using a consistent set of nomenclature. It is designed to analyze and display results using Geographical Information System mapping tools.     

Changes in electrical generator cooling systems: Are they cost-effective sources of water now and under climate change?

In the United States, thermal power plant electrical generators (EGs) are large water diverters and consumptive users who need water for cooling. Retrofitting existing cooling systems to dry cooling and building new facilities with dry cooling can save water and reduce EG's vulnerability to drought. However, this can be an expensive source of water. We estimate that the cost of water saved by retrofitting cooling in existing EGs ranges from $0.04/m³ to $18/m³ depending on facility characteristics. Also water savings from building new EGs with dry cooling ranges in cost per unit water from $1.29/m³ to $2.24/m³. We compare costs with that for water development projects identified in the Texas State Water Plan. We find the water cost from converting to dry cooling is lower than many of the water development possibilities. We then estimate the impact of climate change on the cost of water saved, finding climate change can increase EG water use by up to 9.3% and lower the costs of water saved. Generally, it appears that water planners might consider cooling alterations as a cost competitive water development alternative whose cost would be further decreased by climate change.     

Improving lake riparian source area management using surface and subsurface runoff indices

Sensitivity indices, which rank factors pertinent to surface and subsurface runoff pathways, were used to identify phosphorus source areas in riparian zones of 15 northern Minnesota lakes. Watershed models were first developed using a geographic information system (GIS). Empirical models were then developed correlating water quality with land use, lake morphometry, and riparian sensitivity. Base models of forested, cultivated, pasture/open, wetland and residential land use within 100, 200, 400, and 2000 m of the study lakes were regressed on total phosphorus and chlorophyll-a. Area-weighted groundwater and surface runoff sensitivity indices were then incorporated into each model and tested for significance. Within the 200-m buffer, the total phosphorus base model was improved by including the groundwater index alone. The chlorophyll-a base model at 200 m was improved by including: (1) the groundwater index alone, and (2) both the groundwater and surface runoff sensitivity indices. Results suggest that surface and subsurface runoff analysis of potential source areas can improve decision making for lake riparian management.     

Environmental democracy in action: The Toxics Release Inventory

The Toxics Release Inventory (TRI) created by the 1986 Emergency Planning and Community Right-to-Know Act initially received limited attention. During the early years of its implementation, the TRI has become the basis for a national experiment in voluntaristic problem solving among citizens and industry, but that process of environmental democracy hinges on citizens' ability to actually acquire, understand, and apply the new data on industrial toxic emissions. A national study of TRI-using organizations in the public and private sectors reveals that effective citizen access depends in part on the efforts of intermediary public interest groups to bridge individual needs and right-to-know data. Although the TRI has had early success as a supplement to conventional command and control regulation, questions exist about the extent to which state and federal government should or must provide special efforts to make environmental information access work for citizens.