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111.
The solar phototransformation of furosemide has been investigated in aqueous media. Irradiation of the drug in distilled water, in water and humic acids or nitrate ions, and in sewage sludge water affords a new dehalogenated dimer. The formation of the dimer has been explained by the formation of a cation radical intermediate. The low-measured environmental concentration of furosemide with respect to predicted environmental concentration in the Po and Lambro Rivers could be justified by its phototransformation.  相似文献   
112.
Prey often adopt antipredator strategies to reduce the likelihood of predation. In the presence of predators, prey may use antipredator strategies that are effective against a single predator (specific) or that are effective against several predators (nonspecific). Most studies have been confined to single predator environments although prey are often faced with multiple predators. When more than one predator is present, specific antipredator behaviours can conflict and avoidance of one predator may increase vulnerability to another. To test how prey cope with this dilemma, I recorded the behaviours of lizards responding to the nonlethal cues of a bird and snake presented singly and simultaneously. Lizards use specific and conflicting antipredator tactics when confronted with each predator, as evidenced by refuge use. However, when both predators were present, lizards refuge use was the same as in the predator-free environment, indicating that they abandoned refuge use as a primary mechanism for predator avoidance. In the presence of both predators, they reduced their overall movement and time spent thermoregulating. This shift in behaviour may represent a compromise to minimize overall risk, following a change in predator exposure. This provides evidence of plasticity in lizard antipredator behaviour and shows that prey responses to two predators cannot be accurately predicted from what is observed when only one predator is present.Communicated by W. Cooper  相似文献   
113.
Avian duets are striking for the remarkable precision with which duetting partners sometimes coordinate their songs. Duetting species are taxonomically diverse, and the form of their duets varies. The reasons some birds duet when most do not remains unclear despite numerous hypotheses for its function. I review work done so far on duetting, discuss evidence for and against hypotheses for its functions, and highlight approaches useful for future research. The four hypotheses that appear most promising are that individuals join their partners songs to form duets: (1) to avoid being usurped from a partnership, (2) to prevent their partner being usurped, (3) as a collaborative display in defence of some resource, or (4) to signal commitment to their partner. These hypotheses are not mutually exclusive, and duetting is likely to have multiple roles both within and among species. However, much basic research is still required. Characteristics of duets have rarely been quantified in detail, and information about variability among species in the precision of duetting is necessary, not only to test hypotheses about function, but also to define duetting more precisely. Quantifying the relative frequencies of alternative vocal strategies (for example, remaining silent when a partner sings versus joining in to form a duet) between species and in different contexts will help to determine why partners coordinate their songs to form duets. Furthermore, social systems and sex roles in duetting species are poorly understood, yet understanding these is critical to determining the functions of avian duetting.Communicated by A. Cockburn  相似文献   
114.
GOAL, SCOPE AND BACKGROUND: This paper uses two case studies of U.S. Department of Energy nuclear weapons complex installations to illustrate the integration of expedited site characterization (ESC) and multimedia modeling in the remedial action decision making process. CONCEPTUAL SITE MODELS, MULTIMEDIA MODELS, AND EXPEDITED SITE CHARACTERIZATION: Conceptual site models outline assumptions about contaminates and the spatial/temporal distribution of potential receptors. Multimedia models simulate contaminant transport and fate through multiple environmental media, estimate potential human exposure via specific exposure pathways, and estimate the risk of cancer and non-cancer health outcomes. ESC relies on using monitoring data to quantify the key components of an initial conceptual site model that is modified iteratively using the multimedia model. CASE STUDIES: Two case studies are presented that used the ESC approach: Los Alamos National Laboratory (LANL) and Pantex. LANL released radionuclides, metals, and organic compounds, into canyons surrounding the facility. The Pantex Plant has past waste management operations which included burning chemical wastes in unlined pits, burying wastes in unlined landfills, and discharging plant wastewaters into on-site surface waters. CONCLUSIONS: The case studies indicate that using multimedia models with the ESC approach can inform assessors about what, where, and how much site characterization data needs to be collected to reduce the uncertainty associated with risk assessment. Lowering the degree of uncertainty reduces the time and cost associated with assessing potential risk and increases the confidence that decision makers have in the assessments performed.  相似文献   
115.
Rapid economic and industrial development in Taiwan over the past five decades has elevated the islands standing and earned it a place in the group known as the Four Small Dragons of Asia. Such growth, however, has been at the expense of the environment. There are currently nearly 23 million people juggling for space on the small island of 35,873 km2. Aggravating the matter further, the central mountain ranges and hills take up 73.6% of the land area with some 156 peaks surpassing 3,000 m. As a result, most people live in coastal plains which amount to only 9,490 km2. Pressure to move people inland has led to road construction and deforestation, both of which have contributed to an already high denudation rate of topsoil. As a consequence of this, thirteen rivers in Taiwan are now ranked among the top 20 worldwide in terms of sediment yield. Aside from this, the frequency of both floods and droughts increased prior to 1990, perhaps because of deforestation and global warming. Fortunately, the new conservation-orientated forest management policy of 1991 has alleviated the problem, somewhat, and the occurrence of floods and droughts has since decreased. The problem of water shortage, however, has worsened because of the warming trend in atmospheric temperature. Damming may ameliorate the water shortage problem but may affect the shoreline stability, as well as the ecology and water quality in the estuaries. Furthermore, these detrimental effects may go far beyond the estuaries, and even fisheries on the continental shelves may be affected.  相似文献   
116.
Since the 1940s, some sectors of the sand dune barriers of Buenos Aires Province have been forested to fix the sand in the neighborhoods of resort villages. Man took advantage of the maritime climate and the shallow groundwater to introduce pine forests. Today, these forests reach more than 20 m in height and have developed soils of more than 0.05 m in thickness on former arid sands. Field data were referred to Landsat (TM) composite and Normalized Difference of Vegetation Index, NDVI, images to calculate forest density and covered area. Considering published tables of wood density for each species, the amount of total carbon storage was estimated on 318 t C ha-1 (Mg=106 g) in biomass and 86 t C ha-1 in soils. The three areas analyzed at Miramar, Necochea and Claromecó have captured 658,868 t of carbon in the last 50 years. It is estimated that 150,000,000 t C could be sequestered within temperate dune barriers of Argentina, Uruguay and Brazil. Besides this ecological point of view, there is an important socio-economic factor that cannot be excluded.Presented at and revised subsequent to the 4th LOICZ Open Science Meeting, Bahía Blanca, Argentina. October 1999.  相似文献   
117.
The Ethiopian rift is characterized by a chain of lakes of various sizes and hydrological and hydrogeological settings. The rift lakes and feeder rivers are used for irrigation, soda extraction, commercial fish farming, and recreation, and they support a wide variety of endemic birds and wild animals. The levels of some of these lakes have changed dramatically over the last three decades. Lakes that are relatively uninfluenced by human activities (Langano and Abaya) remain stable except for the usual inter-annual variations, strongly influenced by rainfall. Some lakes have shrunk due to excessive abstraction of water; others have expanded due to increases in surface runoff and groundwater flux from percolated irrigation water. Lakes Abiyata and Beseka, both heavily impacted by human activities, show contrasting lake level trends: the level of Abiayata has dropped by about 5 m over three decades because of the extraction of water for soda and an upstream diversion for irrigation. Beseka has expanded from an area of 2.5 to 40 km2 over the last three decades because of increased groundwater inputs from percolated irrigation water. Lake Awassa has risen slightly due to land use changes resulting in increased runoff in its catchment. This paper addresses these lake level changes and their environmental repercussions, based on evidence from hydrometeorological records, hydrogeological field mapping supported by aerial photography and satellite imagery interpretations, water balance estimation, and hydrological modeling. A converging evidence approach is used to reconstruct the temporal and spatial variations of lake levels. The results reveal that the major changes in the rift valley are mainly related to anthropogenic factors. These changes appear to have grave environmental consequences for the fragile rift ecosystem. These consequences demand the very urgent implementation of integrated basin wide water management practice.  相似文献   
118.
In Sweden, environmental policy is essentially carried out through a system of environmental objectives adopted by Parliament in the late 1990s. This system contains principles, objectives, interim targets, strategies, and follow-up mechanisms, which together provide a solid ground for increased efficiency and improved prioritization in environmental policies. Despite the ambitious approach of the Swedish Parliament, the system of environmental objectives suffers from certain shortcomings. Some of the objectives are imprecise and difficult to evaluate, and there are no rules or principles that may be used to solve goal conflicts and to prioritize between different objectives. As a consequence, the environmental objectives tend to differ in their degrees of operationalizability, and the priority-setting between different objectives is often unclear.*Rskr. denotes a written communication (from the Swedish Parliament to the Swedish Government) of a Parliamentary decision. Note: This version was published online in June 2005 with the cover date of August 2004.  相似文献   
119.
Community-based coastal resource management has been widely applied within the Philippines. However, small-scale community-based reserves are often inefficient owing to management inadequacies arising because of a lack of local support or enforcement or poor design. Because there are many potential pitfalls during the establishment of even small community-based reserves, it is important for coastal managers, communities, and facilitating institutions to have access to a summary of the key factors for success. Reviewing relevant literature, we present a framework of lessons learned during the establishment of protected areas, mainly in the Philippines. The framework contains summary guidance on the importance of (1) an island location, (2) small community population size, (3) minimal effect of land-based development, (4) application of a bottom-up approach, (5) an external facilitating institution, (6) acquisition of title, (7) use of a scientific information database, (8) stakeholder involvement, (9) the establishment of legislation, (10) community empowerment, (11) alternative livelihood schemes, (12) surveillance, (13) tangible management results, (14) continued involvement of external groups after reserve establishment, and (15) small-scale project expansion.These framework components guided the establishment of a community-based protected area at Danjugan Island, Negros Occidental, Philippines. This case study showed that the framework was a useful guide that led to establishing and implementing a community-based marine reserve. Evaluation of the reserve using standard criteria developed for the Philippines shows that the Danjugan Island protected area can be considered successful and sustainable. At Danjugan Island, all of the lessons synthesized in the framework were important and should be considered elsewhere, even for relatively small projects. As shown in previous projects in the Philippines, local involvement and stewardship of the protected area appeared particularly important for its successful implementation. The involvement of external organizations also seemed to have a key role in the success of the Danjugan Island project by guiding local decision-makers in the sociobiological principles of establishing protected areas. However, the relative importance of each component of the framework will vary between coastal management initiatives both within the Philippines and across the wider Asian region.Published on line  相似文献   
120.
Fluctuations of bird abundances in the Midwest region of the United States have been attributed to such factors as landscape change, habitat fragmentation, depredation, and supplemental feeding. However, no attempt has been made to estimate the collective role of landowner activities that may influence birds across a landscape. To investigate how landowners might influence birds when the majority (> 90%) of land is privately owned, we surveyed all 1694 private domestic landowners living on three breeding bird survey routes (120 km) that represent a continuum of rural-to-urban landscapes in Southeastern Michigan from October through December 2000. Our survey was designed to investigate (1) the proportion of landowners involved in bird feeding, providing bird houses, planting or maintaining vegetation for birds, gardening, landscaping, applying fertilizer, and applying pesticides or herbicides; (2) whether differences existed between urban, suburban, and rural landowner activities; and (3) whether landowners that carried out a given activity were sociodemographically different from those who did not. Of the 968 respondents (58.5% response rate), 912 (94%) carried out at least one of the activities on their land and the average landowner carried out 3.7 activities. A total of 65.6% fed birds, 45.7% provided bird houses, 54.6% planted or maintained vegetation for birds, 72.7% gardened, 72.3% landscaped, 49.3% applied fertilizer, and 25.2% applied pesticides or herbicides. Significant differences existed between the landscapes, with rural landowners having more bird houses and applying pesticides or herbicides in greater frequency. Similarly, urban landowners had a greater density of bird feeders and houses, but planted or maintained vegetation in the lowest frequency. Participation in activities varied by demographic factors, such as age, gender, and occupation. Scaling each activity to all landowners, including nonrespondents, across all landscapes indicates that between 14% and 82% of landowners may be engaged in a particular activity, with application of pesticides or herbicides having the least potential involvement (13.9%–55.4%) and gardening having the greatest potential involvement (40.1%–81.6%). Taken collectively, our results indicate that landowners are both intentionally and unintentionally engaged in a wide range of activities that are likely to influence bird populations.  相似文献   
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