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701.
Bird Species Assemblages as Indicators of Biological Integrity in Great Basin Rangeland 总被引:4,自引:0,他引:4
David F. Bradford Susan E. Franson Anne C. Neale Daniel T. Heggem Glen R. Miller Grant E. Canterbury 《Environmental monitoring and assessment》1998,49(1):1-22
The study evaluates the potential for bird species assemblages to serve as indicators of biological integrity of rangelands in the Great Basin in much the same way that fish and invertebrate assemblages have been used as indicators in aquatic environments. Our approach was to identify metrics of the bird community using relatively simple sampling methods that reflect the degree of rangeland degradation and are consistent over a variety of vegetation types and geographic areas. We conducted the study in three range types (i.e., potential natural plant community types) in each of two widely separated areas of the Great Basin: south-eastern Idaho (sagebrush steppe range types) and west-central Utah (salt-desert shrub range types). Sites were selected in each range type to represent three levels of grazing impact, and in Idaho included sites modified for crested wheatgrass production. Birds were sampled by point counts on 9 100-m radius plots at 250-m spacing on each of 20 sites in each area during the breeding season. In sagebrush-steppe, 964 individuals in 8 species of passerine birds were used in analyses. Five metrics were significantly related to impact class, both when analyzed within range type and when analyzed with all range types combined. Species richness, relative abundance of shrub obligate species, and relative abundance of Brewer's sparrow were generally lower for the higher impact classes, whereas the reverse was true for dominance by a single species and for relative abundance of horned larks. In contrast, total number of individuals did not differ significantly as a function of impact class. In salt-desert shrub, a total of 843 birds in 4 species were included in analyses, 98% of which were horned larks. None of the metrics identified above was significantly related to impact class. Two metrics for breeding birds in sagebrush steppe (species richness and dominance) showed little overlap between values for the extremes of impact class, and thus they have potential as indicators of biological integrity. However, the sensitivity of these metrics appears to be greatest at the high impact end of the spectrum, which suggests they may have limited utility in distinguishing between sites having light and moderate impact. 相似文献
702.
Genetic techniques are widely applied to assess the effects of environmental variation or exogenous impacts on populations. Many studies fail to provide convincing evidence that genetic patterns are attributable to the factors proposed. We assert that a rigorous approach must be followed to distinguish patterns of natural genetic variation from genetic change. We review the principles of natural genetic variation and population structure and present them in the context of their interaction with biological and stochastic sources of genetic change. Key steps are articulated which are often overlooked when applying genetic techniques. These are consideration of population structure when comparing populations, developing a specific test against a model of genetic change, and testing for evidence of direct effects and mechanisms of impact. Use of these steps in genetic ecotoxicology is described in detail and includes three primary methods of linking genetic patterns to the effects of contaminants. We propose that this combined approach is critical to the use of genetic techniques to assess and predict long-term effects of environmental impacts on populations or ecosystems. 相似文献
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704.
Jamie W. Baxter John D. Eyles Susan J. Elliott 《Journal of Environmental Planning and Management》1999,42(4):501-525
This paper contributes to the noxious facilities siting literature by exploring some implications of adhering to some recommended principles and practices for competent siting. Through a qualitative case study of a landfill siting process in Peel (Ontario, Canada) three principles are critically assessed: trust; equity; and community participation. While laudable notions in principle, in practice they can impact each other in important ways which can (potentially) undermine the siting process. These impacts result mainly from the failure to achieve meaningful goals associated with one principle (e.g. community participation) which can exacerbate problems achieving goals associated with other principles (e.g. trust). The resulting discord can be further aggravated by the snowballing of adverse effects over time. In particular, practices for achieving trust and equity were adversely linked, as were the relationships between spatial equity and procedural equity and interregional and intraregional equity. These adverse synergisms were linked together with ineffective community participation which brought the process to a halt. Siting inertia (a process momentum difficult to redirect) and an inflexible siting context contributed to these conflicts. Implications for siting and further research are discussed. 相似文献
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有机污染物在水体表面微层的富集行为 总被引:7,自引:0,他引:7
研究邻苯二甲酸二丁酯(DBP),邻苯二甲酸二异辛酯(DEHP)和阴离子表面活性剂在水体表面微层的富集行为.现场分析结果表明邻苯二甲酸酯在小型封闭湖泊表面微层中存在富集现象,富集倍数在1~11之间,湖水的理化性质及采样方式均影响富集倍数的大小.室内微宇宙研究表明DBP和DEHP在微宇宙水体表面微层中均存在富集现象,富集倍数分别为2.81和1.98,藻类、颗粒物和腐殖酸也同时在微宇宙水体表面微层中富集.当水体中加入表面活性物质和腐殖酸时,邻苯二甲酸酯(DBP、DEHP)在表面微层的富集倍数随加入的2种物质浓度的增大而降低.对阴离子表面活性剂的富集动力学研究表明,当表面微层遭到破坏后,其在表面微层达富集平衡需较长时间,水体浓度也影响富集倍数 相似文献
708.
部分水溶性偶氮染料的光催化降解研究 总被引:22,自引:2,他引:20
本研究以高压汞灯为光源,系统地研究了16种偶氮染料在水溶液中的TiO2光催化降解。结果表明,这些偶氮染料的光解为一级动力学反应,采用TiO2光催化降解方法处理所研究的偶氮染料是可行的,并初步探讨了染料的结构与光解反应表观速率常数之间的关系。 相似文献
709.
在利用介质阻挡放电对污染物质CF2ClBr进行等离子体降解产物分析的基础上,进一步研究等离子体系中的电子密度。采用动态反应装置,以平行板电极法直接测量。在CF2ClBr的压力为2kPa时,得出该实验条件下的电子密度约为5.0×10^13/m^3。 相似文献
710.
Chang Xiaoqiang Chen Xingyu Zhang Shuaichen Lu Sixian Zhao Yifan Zhang Dong Yang Lan Ma Yue Sun Peng 《Environmental Chemistry Letters》2023,21(2):681-687
Environmental Chemistry Letters - Branched allylic sulfones are scaffolds widely distributed in bioactive molecules and organic functional materials. The synthesis of allylic sulfones has been... 相似文献