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201.
Summary. The myrmecophilous beetles, Zyras comes (Staphylinidae) and Diaritiger fossulatus (Pselaphidae) are guests of the black shining ant Lasius fuliginosus. Host worker ants never attacked these beetles, and often gave regurgitant to Z. comes following tactile communication with the beetle. By contrast, the workers from colonies without the myrmecophiles showed hostile responses towards Z. comes before tactile contact, but were not aware of D. fossulatus until contact. In L. fuliginosus, workers within a colony shared profiles, but the profiles differed among colonies. GC analyses showed that both Z. comes and D. fossulatus beetles had the same hydrocarbons as L. fuliginosus, and the profiles were more similar to those of the host colony workers than the foreign workers. Both Z. comes and D. fossulatus appear to imitate the hydrocarbon profile of their host workers, allowing integrating into the host nest. A Y-maze bioassay indicated that Z. comes can follow the trail pheromone of L. fuliginosus. This suggests that Z. comes may detect other chemical signals of L. fuliginosus to keep closer interactions with the workers. Received 22 June 2001; accepted 12 November 2001.  相似文献   
202.
Summary. Pyrrolizidine alkaloids (PAs) present a model system in the investigation of tritrophic interactions mediated by plant secondary compounds. However, their toxicity for insect herbivores has never been experimentally proven. Here, we demonstrate the toxic effects of a PA on growth and survival of the eri silk moth Philosamia ricini. In a feeding experiment, larvae of this generalist herbivore fed with an artificial PA diet gained weight significantly slower than control animals, and died as pupae. We suggest that derivatives of the ingested PA N-oxide damage developmental functions during metamorphosis. A tracer test with [14C]senecionine N-oxide revealed that the caterpillars lack adaptations that would prevent conversion of the chemical into the pro-toxic free base. In contrast, the PA adapted leaf beetle Longitarsus anchusae accumulates PAs as N-oxides. We tested the purpose of sequestration in this species as defence against predators. Through a series of prey choice experiments with three carabid predator species, chemically non-protected bark beetle pupae were chosen almost uniformly over L. anchusae pupae. In a following choice test with one of these predators, artificially PA-treated mealworm segments deterred the predator from feeding. Overall the study corroborates the immediate toxic effect of PAs on non-adapted herbivores and the protective effect that adapted insects may gain by sequestering them. It thereby underlines the potential for PAs to play a central role in multitrophic interactions between plants, phytophages and their predators.  相似文献   
203.
化学纤维栅湿式除尘是一种复合机理的新型湿式过滤除尘技术,其过滤风速为2~10m/s,阻力仅为200~500Pa,除尘效率达到99.62%,能很好解决矿山溜井卸矿产生的粉尘,使溜井含尘气流经净化后达到新鲜风流卫生标准。  相似文献   
204.
陕西省干旱灾害的农业风险评估   总被引:4,自引:1,他引:3  
张宏平  张汝鹤 《灾害学》1998,13(4):57-61
分析了陕西干旱发生的时空规律,以缺水率划分干旱标准,评价陕西各季农业干旱状况,并对1949~1990年共42a粮食产量序列进行滑动平均模拟,以粮食减产百分率评估全省干旱灾害等级,得出干旱损失评估模式,使陕西干旱灾害的评估由定性到定量,为其它灾害的定量评估提供了经验。  相似文献   
205.
化学修饰电极在环境微量及痕量有机物分析中的应用   总被引:1,自引:0,他引:1  
根据实验研究及国内外文献,从伏安及电位溶出分析,流动注射/液相色谱电化学检测,化学修饰电极生物传感器及化学修饰电极预富集—石墨炉原子吸收法联用等方面,重点综述了化学修饰电极在环境微量及痕量有机物分析中的应用。  相似文献   
206.
通过应用箱工模型,模拟研究了实施排放标准对大气环境质量的影响,分析讨论了实施2排放标准的技术经济可行性。得出如下结论:(1)重庆市实施大气二氧化硫污染物排放标准能基本满足在气环境质量减级标准的要求。(2)实施标准所需二氧化硫治理静态投资费用总额计26.369亿元。(3)实施标准减少环境污染损失6.440亿元。  相似文献   
207.
The broad objective of this special issue of Mitigation and Adaptation Strategies for Global Change is to address some of the gaps in our knowledge and understanding of the policies, programs, and measures that might be applied to natural hazards and their impacts in an era of climate change. Given the global impacts of climate change and world-wide pattern of increasing losses from natural hazards we necessarily adopt an international perspective. The specific goals of the special issue are to: (a) encompass experiential aspects, emphasizing current practice of mitigation and its associated measures, and their results; and (b) explore primary or root causes of alarming shifts in human and economic costs of environmental extremes. Special emphasis is placed on how human activities are playing a key role in enhancing vulnerability to NTEE (nature-triggered environmental extremes), quite independently from the anthropogenic causes of climate change. The goals are also (c) to examine costs, risks, and benefits (of all kinds including social, political, ecological) of mitigation, and adjustment and adaptation measures; and (d) analyze policy implications of alternative measures. These components are expected to make significant contributions to policy considerations – formulation, implementation and evaluation. There is much uncertainty about the rate of climate change; however, the fact of increase of the atmospheric temperature in the last century is no longer a subject of scientific or policy debate. Due to such changes in the geophysical parameters, certain types of nature-triggered environmental extreme events are likely to continue to increase. How global warming will affect regional climates and pertinent variables is not well known, limiting our ability to predict consequential effects. This factor poses serious constraints against any straightforward policy decisions. Research findings of the work of this volume reaffirm that human dimensions, specifically our awareness and decision-making behavior, are powerful explanatory factors of increasing disaster losses. Disaster mitigation through addressing human, social, and physical vulnerability is one of the best means for contributing to ‘climate change adaptation plans’, and sustainable development goals. Recent lessons from various countries have depicted that the formulation of mitigation strategies cannot be exclusively top-down as it requires social, political, and cultural acceptance and sense of ownership. An interactive, participatory process, involving local communities, produces best expected outcomes concerning mitigation, preparedness, and recovery. An emerging consensus is that there is a need to move towards the ‘mission’ of the International Strategy for Disaster Reduction which aims at building disaster resilient communities by promoting increased awareness of the importance of disaster reduction as an integral component of sustainable development, with the goal of reducing human, social, economic and environmental losses due to natural hazards and related technological and environmental disasters. Sharing of best practices and lessons globally is certain to produce more efficiency and understanding in policy and decision making.  相似文献   
208.
Nowadays, the fine particle pollution is still severe in some megacities of China, especially in the Sichuan Basin, southwestern China. In order to understand the causes, sources, and impacts of fine particles, we collected PM2.5 samples and analyzed their chemical composition in typical months from July 2018 to May 2019 at an urban and a suburban (background) site of Chengdu, a megacity in this region. The daily average concentrations of PM2.5 ranged from 5.6-102.3 µg/m3 and 4.3-110.4 µg/m3 at each site. Secondary inorganics and organic matters were the major components in PM2.5 at both sites. The proportion of nitrate in PM2.5 has exceeded sulfate and become the primary inorganic component. SO2 was easier to transform into sulfate in urban areas because of Mn-catalytic heterogeneous reactions. In contrast, NO2 was easily converted in suburbs with high aerosol water content. Furthermore, organic carbon in urban was much greater than that in rural, other than elemental carbon. Element Cr and As were the key cancer risk drivers. The main sources of PM2.5 in urban and suburban areas were all secondary aerosols (42.9%, 32.1%), combustion (16.0%, 25.2%) and vehicle emission (15.2%, 19.2%). From clean period to pollution period, the contributions from combustion and secondary aerosols increased markedly. In addition to tightening vehicle controls, urban areas need to restrict emissions from steel smelters, and suburbs need to minimize coal and biomass combustion in autumn and winter.  相似文献   
209.
Recent studies associate particulate air pollution with adverse health effects; however, the exposure to indoor particles of outdoor origin is not well characterized, particularly for individual chemical species. We conducted a field study in an unoccupied, single-story residence in Clovis, California to provide data and analyses to address issues important for assessing exposure. We used real-time particle monitors both outdoors and indoors to quantify nitrate, sulfate, and carbon particulate matter of particle size 2.5 μm or less in diameter (PM-2.5). The results show that measured indoor ammonium nitrate concentrations were significantly lower than would be expected based solely on penetration and deposition losses. The additional reduction can be attributed to the transformation indoors of ammonium nitrate into ammonia and nitric acid gases, which are subsequently lost by deposition and sorption to indoor surfaces. A mass balance model that accounts for the kinetics of ammonium nitrate evaporation was able to reproduce measured indoor ammonium nitrate and nitric acid concentrations, resulting in a fitted value of the deposition velocity for nitric acid of 0.56 cm s−1. The results indicate that indoor exposure to outdoor ammonium nitrate in Central Valley of California are small, and suggest that exposure assessments based on total particle mass measured outdoors may obscure the actual causal relationships for indoor exposure to particles of outdoor origin.  相似文献   
210.
主要研究对象为基于离子选择性中性载体的无机离子化学传感器,采用以吸光度为主要测量信号的分光光度法为主要分析方法。依据该传感器的特征,可使分析光束与被测溶液分开,甚至对不透明的液体作分光光度分析。为此,在离子选择性中性载体PVC膜的响应特征基础上设计并研制一种新型结构的光吸收池,应用前景广阔。  相似文献   
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