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471.
Many of Canada's ex-urban and rural areas face a daunting array of sustainability challenges. In developing effective sustainability strategies, these areas must rely heavily upon local resources and capacities and existing social capital. Part of the solution for these areas may lie in multi-stakeholder collaborative approaches built on sustainability principles and strategies. These include the engagement and mobilization of civil society networks; the cultivation of strategic partnerships among key stakeholders in civil society, the private sector and government; and long-term local programmes of research, education and advocacy that are supportive of sustainability. This article describes and analyses a Canadian case study—Dufferin County, part of the Headwaters Country region in southern Ontario—in which a multi-stakeholder, civil society based approach to fostering sustainability is currently unfolding. The ideological and theoretical underpinnings of the initiative are explored, key process-oriented and substantive challenges to the approach are analysed and action research strategies are discussed.  相似文献   
472.
ABSTRACT: Devils Hole is a collapse depression connected to the regional carbonate aquifer of the Death Valley ground water flow system. Devils Hole pool is home to an endangered pupfish that was threatened when irrigation pumping in nearby Ash Meadows lowered the pool stage in the 1960s. Pumping at Ash Meadows ultimately ceased, and the stage recovered until 1988, when it began to decline, a trend that continued until at least 2004. Regional ground water pumping and changes in recharge are considered the principal potential stresses causing long term stage changes. A regression was found between pumpage and Devils Hole water levels. Though precipitation in distant mountain ranges is the source of recharge to the flow system, the stage of Devils Hole shows small change in stage from 1937 to 1963, a period during which ground water withdrawals were small and the major stress on stage would have been recharge. Multiple regression analyses, made by including the cumulative departure from normal precipitation with pumpage as independent variables, did not improve the regression. Drawdown at Devils Hole was calculated by the Theis Equation for nearby pumping centers to incorporate time delay and drawdown attenuation. The Theis drawdowns were used as surrogates for pumpage in multiple regression analyses. The model coefficient for the regression, R2= 0.982, indicated that changes in Devils Hole were largely due to effects of pumping at Ash Meadows, Amargosa Desert, and Army 1.  相似文献   
473.
Lead (Pb) poisoning has been found to be a serious problem for waterfowl in some southern European countries, but few studies have been conducted in Spain. In order to obtain these data, studies were made in the Ebro delta, a Spanish Ramsar site, during 1992 and 1993. Lead shot densities in the first 20 cm of sediment ranged from < 8 900 to 2 661 000 shot ha(-1). A similar proportion of birds had lead shot in the gizzard and elevated liver lead (> 5 microg g(-1) DW) concentrations. Northern pintail and common pochard (both with declining populations in Europe) showed the highest levels of shot ingestion, with 70.8 and 69.2%, respectively. Body condition index in the northern pintail was negatively correlated with the number of pellets in the gizzard and liver Pb concentration. Levels of exposure were higher than in other northern countries of the western Palearctic flyway, where lead shot have been banned recently.  相似文献   
474.
L. Uttal  K. R. Buck 《Marine Biology》1996,125(2):333-343
This study presents the first quantification of the diet of a gelatinous midwater organism on a temporal basis. Using the Monterey Bay Aquarium Research Institute's remotely operated vehicle Ventana, regular collections of the polychaete Poeobius meseres (Heath, 1930) over a 1 yr period (October 1990 to November 1991) in Monterey Bay yielded intact organisms for the study of feeding behavior and quantitative analysis of stomach contents. In situ observations showed P. meseres feeding in two different ways: (1) by deployment of a mucus web in the water column that passively collects particles for consumption; and/or (2) by grasping detrital material in the water column with its ciliated tentacles. Stomach-content analyses showed that P. meseres is primarily coprophagic, its diet being dominated by fecal pellets from euphausiids and copepods. These fecal pellets appear to provide P. meseres with essentially all its carbon. Although fecal pellets were the most important food item volumetrically, P. meseres also consumed large numbers of diatoms and small numbers of dinoflagellates, chrysophytes, radiolarians, foraminiferans and eggs. The diet of P. meseres appears to reflect primary productivity in the surface waters, with different food items predominant in the diet at different times of the year. Pennate diatoms were most abundant in the diet during the fall, centric diatoms were most abundant during the sumnier, and fecal pellets during the winter. The composition of P. meseres diet suggests that this and other midwater gelatinous organisms have a significant role in the remineralization of particles as they sink from the surface to the deep sea.  相似文献   
475.
Model oligo esters of terephthalic acid with 1,2-ethanediol, 1,3-propanediol, and 1,4-butanediol have been investigated with regard to their biodegradability in different biological environments. Well-characterized oligomers with weight-average molar masses of from 600 to 2600 g/mol exhibit biodegradation in aqueous systems, soil, and compost at 60°C. SEC investigations showed a fast biological degradation of the oligomer fraction consisting of 1 or 2 repeating units, independent of the diol component used for polycondensation, while polyester oligomers with degrees of polymerization higher than 2 were stable against microbial attack at room temperature in a time frame of 2 months. At 60°C in a compost environment chemical hydrolysis also degrades chains longer than two repeating units, resulting in enhanced degradability of the oligomers. Metabolization of the monomers and the dimers as well by the microorganisms could be confirmed by comparing SEC measurements and carbon balances in a Sturm test experiment. Based on these results degradation characteristics of potential oligomer intermediates resulting from a primary chain scission from copolyesters consisting of aromatic and aliphatic dicarbonic acids can be predicted depending on their composition. These results will have an evident influence on the evaluation of the biodegradability of commercially interesting copolyesters and lead to new ways of tailor-made designing of new biodegradable materials as well.  相似文献   
476.
Age and growth of the alfonsino Beryx splendens from New Caledonia seamounts were determined by examination of whole and sectioned otoliths. One growth-ring (annulus) in the otoliths appears to be laid down each year. It consists of one opaque (summer, fast-growing) zone and one hyaline (winter, slowgrowing) zone. Thin-sections of otoliths revealed daily rings which allowed us to estimate that the formation of the nucleus takes 10 mo. The first annulus following the nucleus is incomplete. Females have a higher growth rate than males. Sexual maturity is reached at the age of 7 to 8 yr for males and 6 yr for females. Maximum age attained would be 20 yr for alfonsino >50 cm in fork length. the results are compared with those from the few other studies on the growth of alfonsino.  相似文献   
477.
Ambient concentrations of ozone (O(3)) and carbon dioxide (CO(2)) were measured at locations from the forest floor to the top of the canopy in a deciduous forest at the Moshannon State Forest in northcentral Pennsylvania. O(3) concentrations were measured from May-September for three years (1993-1995) while CO(2) concentrations were measured only during July and August of 1994. O(3) concentrations increased steadily during the day at all locations, peaking during the middle to late afternoon hours. O(3) concentrations then steadily declined to their lowest point, just before dawn. Vertical O(3) concentration gradients varied seasonally and among years. However, O(3) concentrations were highest within the forest canopy and lowest at the forest floor, with an average difference of approximately 13%. Differences in O(3) concentrations between the canopy and forest floor were greatest at night. O(3) concentrations were slightly higher at locations within the canopy than above the canopy. CO(2) concentrations were consistenly higher near the forest floor and were higher above the canopy than within the canopy. CO(2) concentrations were higher at night than during the day at all locations, especially near the forest floor.  相似文献   
478.
Wild rodents (Mus domesticus) were collected in three areas in Rome exposed to different traffic flows to ascertain a possible correlation between genetic damage and heavy metal concentration. The concentration of lead, cadmium and zinc were determined in liver, kidney and bones and two mutagenicity tests (micronucleus test and sperm abnormality assay) were employed. The results obtained showed that the contents of lead and cadmium were higher in animals collected in areas with high traffic flows than in those from control areas. A statistically significant increase of the frequency of micronucleated erythrocytes and of abnormal sperm cells was also obtained in animals collected in sites with high traffic flows. The investigation confirmed the suitability of using wild rodents as bioindicators of environmental pollution and as key-organisms in programs of pollution monitoring and environmental conservation.  相似文献   
479.
ABSTRACT: Recurrent calls for integrated resource management urge that an understanding of human activities and populations be incorporated into natural resource research, management, and protection efforts. In this paper, we hypothesize that watersheds can be a valuable geography for organizing an inquiry into the relationship between humans and the environment, and we present a framework for conducting such efforts. The framework is grounded in the emerging field of landscape ecology and incorporates demographic theory and data. Demography has been advanced by technological capabilities associated with the 1990 Census. Employing Geographic Information System (GIS) tools, we couple Landsat Thematic Mapper (TM) land cover data with census‐derived housing density data to demonstrate the operation of our framework and its utility for better understanding human‐landscape interactions. In our investigation of the Kickapoo Watershed and two sub‐ watersheds, located in southwestern Wisconsin, we identify relationships between landscape composition and the distribution and social structure of human populations. Our findings offer insight into the interplay between people and biophysical systems.  相似文献   
480.
ABSTRACT: A procedure using a simple, empirically‐based model that makes efficient use of available information has been developed for designing a ground water monitoring well network. A moving plume is described by siting wells in a sequential manner, relying upon two‐dimensional concentration data obtained from previously installed wells to determine the locations of future wells. Data sets from two well known, densely monitored natural gradient tracer studies were used to test the procedure. Plumes defined by all information in the original networks were compared to those defined by reduced networks designed by the new procedure. The new procedure tracked the plumes using only a portion of that information. The new procedure could have reduced the number of wells in the original tests by about 50 percent without appreciable loss of plume information as measured by plume location and extent and by tracer mass.  相似文献   
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