阊江河1～6级支流大型底栖无脊椎动物取食功能团演变特征

河流连续性概念(rivercontinuumconcept,RCC)将自然河流生态系统视为物理和生物的连续体,河流物理环境的梯度变化决定了生物的演变格局.为探索自然河流系统受人类干扰后大型底栖无脊椎动物的演变规律,作者于2002年5月、8月、11月对安徽省祁门县阊江河1~6级支流的大型底栖无脊椎动物进行了调查,共获7纲57科101属119种,计8813头,并详细记载了各级支流样点的栖境特点.运用“河流连续性概念”理论分析结果表明该河1~6级支流大型底栖无脊椎动物各取食功能团演变趋势符合该理论,但上游至下游的生物区系演替程度明显小于未受干扰的自然河流,1~6级支流各功能团的分布(P/%)梯度变化趋于平缓,仅捕食者数量分布与理论预测模式比较接近.各级支流相同取食功能团的优势类群各异,其种类的耐污能力随河流级别的增加总体呈上升趋势.同级支流各取食功能团的分布(P/%)比例存在季节性差异.图2表3参15     

The ecosystem and autonomy: A reconsideration of the ecosystem concept (I)

A critical review of the development of the ecosystem concept is presented in this paper. An attempt to define the concept is discussed in details with reference to autonomy.     

应急预案以人为本

从国家总体应急预案的框架入手，分析了其方方面面的编制要素，得出了其以人为本的编制理念的结论。     

我国绿色物流的发展现状和应对措施

所谓绿色物流,就是以降低对环境的污染、减少资源消耗为目标的物流活动。但是,绿色物流的理念才刚刚传入我国,对政府和企业而言都还是一个全新的话题,不少企业对其重要性还缺乏认识。对此,政府应该根据5R原则对企业进行规制与政策激励,加强企业的环境自律和消费者的绿色理念宣传,把绿色理念的传播贯穿全社会。     

"城中村"改造的效益分析

我国城市化进程的快速发展、城乡二元管理体制和土地二元所有制结构导致了"城中村"的形成.为落实科学发展观,促进城市全面、协调发展,必须对"城中村"加强管理,完善基础设施,改善卫生条件,规范土地的使用.通过"城中村"的改造能提高城市土地利用率,改善居住环境、投资环境和生态环境,更好地建设资源节约型、环境友好型社会.     

高等数学概念教学的探索

概念教学是数学教学的核心.但是,高等数学中概念众多,并且又都包含着运动、变化等辨证观点,对于习惯于按静止观点学习初等数学的"大一"新生来讲,理解和掌握这些数学概念确有一定的难度.因此,在教学中要重视概念的引入,揭示概念的本质,加强概念的应用,将数学知识与专业知识紧密联系起来.     

科学发展观与中国传统文化

从分析传统发展模式的种种弊端与现阶段我国经济增长方式存在的主要问题入手,论述了科学发展观的科学含义和现实意义,并试图从中国传统文化的角度去挖掘科学发展观深邃的思想内涵。     

事故隐患防治与超前安全教育的哲学思考

应用辩证唯物主义的哲学观念,阐述了事故隐患的特征和规律,对隐患类型进行归纳,确定其防治对策──超前安全教育。阐述安全超前教育特点,要求着力处理解决８个方面的问题,以利于科学地掌握安全超前教育方法。     

A statistical F test for the natural attenuation of contaminants in groundwater

Natural attenuation (NA) is a catchall explanation for the overall decay and slowed movement of the contaminants in the subsurface. One direct support to NA is to demonstrate that contaminant concentrations from monitoring wells located near the source are decreasing over time. The decrease is summarily expressed in terms of an apparent half-life that is determinedfrom the line best fitting the observed log-transformed concentration data and time. This simple (time-only) decay modelassumes other factors are invariant, and so is flawed when complicating factors – such as a fluctuating water table – are present. A history of the water-table fluctuation can track changes in important NA factors like recharge, groundwater flow direction and velocity, as well as other non-NA factors like volume of water in and purged from the well before a sample is collected. When the trend in the concentrations is better associated with the water table rising or falling, any conclusionabout degradation rate may be premature. We develop simple regressions to predict contaminant concentration (c) by two line models: one involving time (c c(t)), and another involving groundwater elevation (c c(z)). We develop a third model that includesboth factors (c c(t, z)). Using an F-test to compare the fits to the models, we determine which modelis statistically better in explaining the observed concentrations. We applied the test to sites where benzene degradation rates had previously been estimated. The F-testcan be used to determine the suitability of applying non-parametric statistics, like the Mann-Kendall, to the concentration data, because the result from the F-test canindicate instability of the contaminant plume that may bemasked when the water table fluctuates.     

Rural poverty driven soil degradation under climate change: the sensitivity of the disposition towards the Sahel Syndrome with respect to climate

Starting from the basic assumption of the syndrome concept that essentially all of the present problematic civilization–nature interactions on the global scale can be subdivided into a limited number of typical patterns, the analysis of the response of these patterns (syndromes) to climate change can make a major contribution to climate impact research, surmounting the difficulties of more common sectoral ceteris paribus impact studies with respect to their systemic integration. In this paper we investigate in particular the influence of climate on the regional proneness or disposition towards one of the most important syndromes with respect to famines and malnutrition, the Sahel Syndrome. It describes the closely interlinked natural and socioeconomic aspects of rural poverty driven degradation of soil and vegetation on marginal sites. Two strategies of global climate impact assessment on a spatial 0.5°×0.5° grid were pursued: (a) As a measure for the climate sensitivity of the regional proneness, the absolute value of the gradient of the disposition with respect to the global field of 3} 12 monthy normals of temperature, irradiation and precipitation is calculated. (b) The disposition was evaluated for two different climate forecasts under doubled atmospheric CO₂ concentration. For both strategies two new quantitative global models were incorporated in a fuzzy-logic-based algorithm for determining the disposition towards the Sahel Syndrome: a neural-net-based model for plant productivity and a waterbalance model which calculates surface runoff considering vertical and lateral fluxes, both driven by the set of 36 monthly climatological normals and designed to allow very fast global numerical evaluation.Calculation (b) shows that the change in disposition towards the Sahel Syndrome crucially depends on the chosen climate forecast, indicating that the disagreement of climate forecasts is propagated to the impact assessment of the investigated socio-economic pattern. On the other hand the regions with a significant increase in disposition in at least one of the climate scenario-based model runs form a subset of the regions which are indicated by the local climate sensitivity study (a) as highly sensitive – illustrating that the gradient measure applied here provides a resonable way to calculate an upper limit or worst case of negative climate impact. This method is particularly valuable in the case of uncertain climate predictions as, e.g., for the change in precipitation patterns.