The Impact of Landsat Satellite Monitoring on Conservation Biology

Landsat 7s recent malfunctioning will result in significant gaps in long-term satellite monitoring of Earth, affecting not only the research of the Earth science community but also conservation users of these data. To determine whether or how important Landsat monitoring is for conservation and natural resource management, we reviewed the Landsat programs history with special emphasis on the development of user groups. We also conducted a bibliographic search to determine the extent to which conservation research has been based on Landsat data. Conservation biologists were not an early user group of Landsat data because a) biologists lacked technical capacity – computers and software – to analyze these data; b) Landsats 1980s commercialization rendered images too costly for biologists budgets; and c) the broad-scale disciplines of conservation biology and landscape ecology did not develop until the mid-to-late 1980s. All these conditions had changed by the 1990s and Landsat imagery became an important tool for conservation biology. Satellite monitoring and Landsat continuity are mandated by the Land Remote Sensing Act of 1992. This legislation leaves open commercial options. However, past experiments with commercial operations were neither viable nor economical, and severely reduced the quality of monitoring, archiving and data access for academia and the public. Future satellite monitoring programs are essential for conservation and natural resource management, must provide continuity with Landsat, and should be government operated.     

IMPLICATIONS OF C.A.R.E. VS. SOUTHVIEW FARM ON THE U.S. LIVESTOCK AND POULTRY INDUSTRY1

ABSTRACT: On May 19, 1993, a jury in the U.S. District Court for the Western District of New York found Southview Farm and Richard H. Popp guilty of violating the Clean Water Act on five occasions. The violations were the result of storm water runoff from a site used for disposal of dairy cattle manure from an unpermitted concentrated animal feeding operation. The presiding District Court judge later dismissed the jury verdict, and subsequently a U.S. Court of Appeals for the Second Circuit reversed the dismissal. The Court of Appeals concluded that the discharges were not exempt as agricultural storm water discharges, and that the manure spreaders involved were point sources. Because the use of animal manures in crop production activities will result, unavoidably, in the discharge of some pollutants to adjacent surface waters, a rational and universally applicable basis is needed to determine when such discharges are point versus nonpoint source. Current statutes and regulations do not delineate clearly such a boundary. To address this lack of specificity, I propose that application rates be based on recommended crop nutrient needs.     

饮用水中的消毒副产物及其控制策略

消毒副产物(disinfection by-products,DBPs)是在饮用水消毒时由消毒剂与有机或无机前体物反应生成的一类次生污染物,其由于具有致癌、致畸和致突变的三致特性在全球范围内广受关注.聚焦于饮用水中的DBPs,介绍了DBPs的主要分类和研究历程,汇总了多地饮用水中常见DBPs的浓度水平以及全球饮用水水质标准对DBP指标的管控要求.随后系统介绍了饮用水中DBPs的控制策略,包括源头控制、过程控制、末端控制以及协同控制这4大类,并对各类控制方法的优缺点进行了分析.评述了中国的DBPs研究的现有水平和未来趋势,并展望了未来有关DBPs控制方法的研究方向.一方面,在评价某种工艺或技术对DBPs的控制效果时需要考虑DBPs浓度和水质综合毒性的变化,另一方面,建议关注耦合源头、过程和末端控制技术的协同控制方法,兼顾从源头到龙头每个节点,实现对饮用水中各类DBPs的高效控制.     

Johnson & Ettinger模型和Volasoil模型在污染物室内挥发风险评价中的应用和比较

在土壤污染和地下水污染的现场,挥发过程是挥发性污染物暴露的重要途径.设置典型土壤污染场景作为研究对象,选取Johnson&Ettinger模型和Volasoil模型进行室内挥发过程的模拟和暴露浓度的计算.对两个模型中污染物的运移机理进行了比较和分析.尽管方法和参数选择有所不同,二者对污染源处三相平衡浓度的计算本质上是一致的.暴露浓度的计算结果表明,两个模型对室内挥发过程的模拟可能会有较大差异,与污染现场的具体情况有关.参数影响的分析表明,污染源顶部埋深对二者暴露浓度的影响一致,Johnson&Ettinger模型对污染土壤含水率的大小非常敏感.建议考虑房屋结构的实际情况,选用或者改进模型进行室内挥发过程的评价.     

考虑应变速率影响的混凝土重力坝非线性地震响应分析

通过引入应变速率、损伤变量以及刚度退化指标等参数,建立了应变率相关的混凝土弹塑性损伤模型。运用该模型对某重力坝厂房坝段分别就率相关及率无关两种情况进行了三维非线性地震响应时程分析。深入研究了混凝土应变速率等相关特性对结构动力响应的影响。结果表明,应变速率对混凝土的力学性能有一定的影响,随着应变速率的增加,坝体结构的变形减小,主拉应力有所提高,应变能有所减小以及开裂损伤有一定的降低。所得结论对混凝土重力坝的震害研究有一定的参考价值。     

Weather-mediated natural selection on arrival time in cliff swallows (Petrochelidon pyrrhonota)

An unusually long period of cold weather in May 1996 caused extensive mortality among insectivorous cliff swallows (Petrochelidon pyrrhonota) in the northern and central Great Plains. We analyzed how viability selection affected spring arrival time in a migratory Nebraska population by comparing capture histories of survivors with those of birds known to have died and by documenting how arrival time changed in the year following the selection event. Surviving birds had significantly later first-capture dates (an index of arrival time) in the years prior to selection than those that died; a significant selection differential suggested directional selection for birds that arrived later. Colony sites were occupied significantly later following the selection event, and the distribution of first-capture dates in the season after selection was significantly shifted toward later arrivals. Offspring of the survivors tended to arrive later than birds of the same age prior to the selection event. While major weather-caused mortality events of this magnitude are rare in the study area, spells of cold weather severe enough to cause limited mortality are frequent in April and early May. At least 25 probable mortality events of varying severity were identified in the last 50 years based on climatological data. Periodic weather-mediated selection against early arrival constrains the cliff swallow’s breeding season and may partly prevent directional selection for earlier nesting. Received: 19 October 1999 / Received in revised form: 15 January 2000 / Accepted: 24 January 2000     

Life history costs of olfactory status signalling in mice

Large body size confers a competitive advantage in animal contests but does not always determine the outcome. Here we explore the trade-off between short-term achievement of high social status and longer-term life history costs in animals which vary in competitive ability. Using laboratory mice, Mus musculus, as a model system, we show that small competitors can initially maintain dominance over larger males by increasing investment in olfactory status signalling (scent-marking), but only at the cost of reduced growth rate and body size. As a result they become more vulnerable to dominance reversals later in life. Our results also provide the first empirical information about life history costs of olfactory status signals. Received: 15 December 1999 / Revised: 6 June 2000 / Accepted: 24 June 2000     

不同墩高下连续刚构桥抗震性能分析

以某大跨连续高墩刚构桥为依托,采用Midas/civil软件建立仿真模型,通过时程分析方法研究双肢薄壁墩参数在地震响应下对高墩连续刚构桥抗震性能的影响.以桥墩高度为主要参数,以模型阵型频率、桥墩墩顶、墩底位移及内力变化三个方面对其抗震性能进行评价.研究结果表明,随着其中一个桥墩高度的增加,桥梁频率不断减小,矮墩墩底及矮...     

浅谈音乐与体育之缘

音乐与体育作为人类社会独特的文化现象,在不同时期以各种形式相互融合,共同构成人类自身情感的表达方式,成为“世界语言”。现代社会,音乐以其特有的审美、教育、娱乐功能对社会的进步和发展起着积极的作用。尤其是音乐与现代奥运会结合,传承了奥林匹克精神,扩大奥运会的影响,展示了民族的文化,让我们真实地感受到一种前所未有的改变世界的力量。