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Long-term exposure of animals to sub-lethal doses of toxicants such as benzene (B) and dimethylnaphthalene (DMN) may result in subtle changes in their physiology and biochemistry. In crustaceans such changes include decreased rate of limb regeneration, extended time to molt and decreased growth increment at molt.1,2 These processes depend upon an adequate supply of stored nutrients in the tissues and appropriate release of neuroendocrine substances from the central nervous system.3,4 We are examining the effects of sub-lethal doses of B and DMN on osmotic and ionic regulation and on nutrient storage in the blue crab, Callinectes sapidus, and the green crab, Carcinus maenas. Disturbances in these physiological processes may reflect alterations in neuroendocrine functions brought about by the presence of toxicants. We find that exposure of C. maenas to B or DMN, followed by transfer to a dilute medium, results in impaired osmoregulatory capacity, while addition of these compounds to a dilute medium to which the animal is already acclimated does not affect their regulatory ability. Storage of carbohydrate in the midgut gland (hepatopancreas) is decreased by B or DMN, while the accessory storage tissues (gill, muscle) are not significantly affected. 相似文献
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Liza Tonkin 《The Australian geographer》2004,35(1):59-75
Place‐based action (PBA) features prominently in labour geographies, particularly in restructuring politics, and is consistently employed as an enduring union tactic, yet it remains relatively undervalued in steel restructuring accounts, with common approaches emphasising the class instability and limitations of such action. In contrast, and to redress the apparent imbalance, this paper argues the merit of recognising PBA as a distinct movement‐based politic with specific forms of representation and empowerment. Such an approach should lead to greater recognition and appreciation of the impact that PBA has had historically. To illustrate this, a case study is presented of how local groups used place‐based action in Wollongong to shape steel restructuring politics and industry policy during the 1980s. Although powerful, the influence of PBA diminished at the policy writing stage. Rather than devaluing all benefits from PBA due to such limitations, it is suggested that the constraints on PBA at this point suggests the need for other forms of intervention. It is concluded that the approach suggested here highlights when other tactics are required, strengthening real‐world tactical analysis. 相似文献
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Jae-Seok Kim Anna Liza Bais Sun-hee Kang Jaehoon Lee Kihong Park 《Journal of Atmospheric Chemistry》2011,68(3):251-263
Ammonia has a short residence time in the atmosphere and rapidly neutralizes acid gases that occur near its source, requiring a rapid measurement system for ammonia and particulate ammonium concentrations to better understand their sources, temporal variation of ammonia emissions, and the formation of secondary ammonium aerosols. A semi-continuous measurement system, consisting of a diffusion scrubber, a particle growth chamber, an air-liquid separator, and a fluorescent detector, was developed to determine both gaseous ammonia (NH3) and particulate ammonium (NH 4 + ) in PM2.5 in the ambient atmosphere of Gwangju, South Korea, during the months of March, April, July, and September of 2007. During the sampling periods, the average concentrations of ammonia and ammonium were found to be 2.33?±?1.29 μg/m3 and 1.89?±?0.99 μg/m3, respectively. Although the average gaseous ammonia concentration was highest in March, the particulate ammonium concentration was higher during the warmer season, reaching 2.08?±?1.07 μg/m3 and 2.32?±?0.94 μg/m3 in April and July, respectively, while only 1.68?±?0.61 μg/m3 in March and 1.24?±?0.99 μg/m3 in September. It is proposed that the higher availability of acid species during the warmer months produced a significant amount of particulate ammonium sulfate. Diurnal fluctuation of ammonia and ammonium during the warmer months showed that their peak time occurred at approximately 10:00 am. Both ammonia and ammonium concentrations were better correlated during the warmer months than during the cooler months. Further, the data suggest that the ammonia and ammonium were measured under well dispersed conditions, and multiple sources contributed to the ammonia at the sampling site. 相似文献
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Patrick Christie David L. Fluharty Alan T. White Liza Eisma-Osorio William Jatulan 《Marine Policy》2007
This analysis documents the reasons for emerging interest in ecosystem-based fisheries management (EBFM) and relates this management model to others. It highlights the central challenges to EBFM in the tropical context and examines an ongoing project, Fisheries Improved for Sustainable Harvest (FISH), in the Philippines—likely the first EBFM project in the tropics. The Philippine legal and institutional context provides major governance challenges to EBFM, especially as management is scaled up. A monitoring framework with process and output criteria is applied to FISH to establish progress to date. Major institutional and governance challenges for EBFM will require monitoring, evaluation, and adaptation. 相似文献
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Nitrogen inputs restructure ecosystems and can interact with other agents of ecological change and potentially intensify them.
To examine the effects of nitrogen combined with those of elevation and competition, in 2005 we mapped vegetation and elevation
within experimental plots that have been fertilized since 1970 in Great Sippewissett salt marsh, Cape Cod, MA, USA and compared
the resulting effects on marsh vegetation. Decadal-scale chronic nutrient enrichment forced changes in cover and spatial distribution
of different species. With increasing enrichment, there was a shift in species cover primarily involving loss of Spartina alterniflora and an increase in Distichlis spicata. Percent cover of near monocultures increased with nitrogen fertilization, owing mainly to the proliferation of D. spicata. The experimental fertilization prompted a shift from the short form of S. alterniflora to taller forms, hence increasing above-ground biomass, where this species managed to remain. Chronic enrichment increased
upper and lower limits of the elevation range within which certain species occurred. The shift to increased cover of D. spicata was also associated with faster accretion of the marsh surface where this species was dominant, but not where S. alterniflora was dominant. Interactions among nutrient supply, elevation, and competition altered the direction of competitive success
among different species of marsh plants, and forced changes in the spatial distribution and composition of the salt marsh
plant communities. The results imply that there will be parallel changes in New England salt marshes owing to the widespread
eutrophication of coastal waters and the increasing sea level rise. Knowing the mechanisms structuring marsh vegetative cover,
and their role in modification of salt marsh accretion, may provide background with which to manage maintenance of affected
coastal wetlands. 相似文献
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Abstract: The River Environment Classification (REC) provides a GIS‐based tool to differentiate between biophysical attributes of river systems. This study tests the effectiveness of the REC as a tool to differentiate physical habitat and macroinvertebrate assemblages between four classes of stream in the Auckland region. Results indicate significant within‐class variability in physical habitat and macroinvertebrate assemblages, with considerable overlap among the four classes. Biophysically meaningful stream classes cannot be identified from GIS‐derived data applied in this research. Field analyses of physical habitat (i.e. geomorphic river condition) are required as a supplementary tool to interpret ecological relationships for differing stream types. 相似文献
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Liza Griffin 《Geoforum》2010,41(2):282-292
This paper explores a series of maxims, widely known in policy and academic circles as the ‘principles of good governance’, which state that policymaking in the European Union (EU) should be participatory, conducted as close to citizens as practicable, transparent, accountable, effective and coherent. These maxims were introduced into EU fisheries management as part of a radical reform of the Common Fisheries Policy (CFP) in 2002. This reform was instituted in response to criticisms of a prevailing management regime alleged to be inefficient, undemocratic, and potentially responsible for an environmental crisis: the exhaustion of key fish stocks. The research for this work has found that there are limits to the actual achievement of good governance in EU fisheries. In practice governance innovations are very often contradictory and rife with tensions. I reason that such problems result not merely from policy implementation failures; they constitute a more endemic feature of the CFP reforms. We can begin to understand these limits to good governance principles by looking to Agamben’s permanent state of exception thesis. Agamben’s theory helps to show how these contradictions and tensions occur under new governance regimes, because the relationship between democratic norms (like good governance) and political power is no longer clear. I argue that this blurring has been exploited by groups seeking influence in these new regimes. They do this through citing a supposed need for emergency measures to mitigate crisis. Although this research broadly supports the state of exception thesis, my analysis leads me to question some aspects of its application in contemporary governance spaces. 相似文献
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Liza Grandia 《Geoforum》2009,40(5):720-731
As a microcosm of the global livestock-climate problem, this tale of two hegemonies explores how and why two critical constituencies—development planners and conservation professionals—have failed to see the “raw hides” of cattle’s impact on the Maya Biosphere Reserve in northern Guatemala. Based on ethnographic research carried out between 1993 and 2007, this paper seeks to explain the idealization, persistence, and normalization of cattle as a land use in Petén from the colonial period to the present. Framed with a Gramscian analysis of the critical role of organic intellectuals in catalyzing social change, I explore the mental feedback loops reinforcing other social and environmental causes of land degradation in this region. After presenting data on the historical expansion of cattle into the Guatemalan lowlands through government colonization programs, I describe how multilateral lending agencies like the World Bank continue to corral development plans in the region. The next part of the paper explores the complex and ambiguous relations between conservation professionals and the ranching sector. I then conclude with a discussion of how global trade and infrastructure projects such as the Puebla to Panama Plan and the Central America Free Trade Agreement will further mask the hegemonic hides of cattle. 相似文献
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Kevin L. Garas Madonna Feliz B. Madrigal Ross Dominic D. Agot Mark Carlo M. Canlas Liza Socorro J. Manzano 《中国岩溶》2020,39(6):928-936
岩溶研究中,通常会使用高分辨率卫星图像和地理空间数据识别、描绘岩溶发育及相关地质灾害发生的地貌特征。本文旨在利用ArcGIS10.0确定干涉合成孔径雷达数字高程模型（IFSAR-DEM）识别、量化和描述岩溶洼地。这种半自动岩溶洼地/天坑探测方法采用水流模拟法,并结合（1）流域划分;（2）下沉填充法提取洼地特征;（3）下沉深度测量及分类;（4）使用2013年至2014年谷歌高光谱卫星图像和数字地形模型对探测到的岩溶洼地进行验证。该方法已在薄荷省旁劳市进行的评估中进行了预测试。使用国家测绘资源信息局（菲律宾）1991年的1:50 000比例尺地形图进行的初步封闭洼地分析,发现旁劳岛有15个天坑。利用5米高分辨率IFSAR-DEM,共探测到820个天坑,其中424个根据详细的地面实况进行了描绘,以验证了岩溶洼地的存在。地表实况包含天坑大小、形状和深度等基本形态测量分析以消除误报数据。阈值设定为沉降深度大于1米,孔径大于10米,从而最大程度精确区分实际的天坑。这种基于GIS的工具有助于生成高分辨率岩溶塌陷易发区图,继而指导当地规划者、工程师及决策者进行开发规划和土地利用。 相似文献
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