Environmental assessment is an intriguing policy phenomenon: it is employed in an ever-increasing range of contexts the world-over, yet research indicates it rarely efficiently or effectively achieves its principal purpose of promoting sustainable development. Increasingly, practical limitations in the effectiveness of environmental assessment are attributed to its theoretical shortcomings, particularly in relation to the conception of causation. This research advanced debate on environmental assessment by examining the theoretical implications of an empirical analysis of its causal operation in purposefully selected cases. The causal models derived from the research data illustrate the diversity of mechanisms through which environmental assessment can contribute to sustainability, and provide an insight into the complexity and contextuality of causation in the empirical realm. The research findings also highlight a multiplicity of societal expectations concerning environmental assessment's contribution to sustainable development. It is concluded that the interplay of non-rational variables (such as power, agency, experiences and expectations) necessitates the pursuit of a reflexive accommodation of purposes, methods and context in environmental assessment practices. 相似文献
We investigated whether fish assemblage structure in southern Appalachian streams differed with historical and contemporary
forest cover. We compared fish assemblages in 2nd–4th order streams draining watersheds that had increased forest cover between 1950 and 1993 (i.e., reforesting watersheds). We sampled fish in 50 m reaches during August 2001 and calculated catch-per-unit-effort (CPUE)
by taxonomic, distributional, trophic, reproductive, and thermal metrics. We assigned streams to reforestation categories
based on cluster analysis of years 1950 and 1993 near-stream forest cover. The relationship between forest cover and assemblage
structure was assessed using analysis of variance to identify differences in fish CPUE in five forest cover categories. Streams
contained 23 fish species representing six families, and taxa richness ranged from 1 to 13 at 30 stream sites. Streams with
relatively low near-stream forest cover were different from streams having moderate to high near-stream forest cover in 1950
and 1993. Fish assemblages in streams having the lowest amount of forest cover (53–75%) were characterized by higher cosmopolitan,
brood hider, detritivore/herbivore, intermediate habitat breadths, run-pool dweller, and warm water tolerant fish CPUE compared
to streams with higher riparian forest cover. Our results suggest that fish assemblage’s structural and functional diversity
and/or richness may be lower in streams having lower recent or past riparian forest cover compared to assemblages in streams
having a high degree of near-stream forest cover. 相似文献
The extent to which perfluorooctanesulfonate precursors (PreFOS) play a role in human or environmental exposure to perfluorooctanesulfonate (PFOS) is not well characterized. The diversity of manufactured PreFOS and its degradation products (e.g. C(8)F(17)SO(2)R and C(8)F(17)SO(2)NR'R', where R is H or F, and R' and R' are various) has made it difficult to track their fate. Temporal trends of PFOS in both humans and wildlife are discrepant, thus it is difficult to predict future exposure, and hypotheses about the role of PreFOS have been raised. Although abiotic degradation of commercially important PreFOS materials requires further research, current data suggest that the yield of PFOS is negligible or minor. On the other hand, in vivo biotransformation of PreFOS yields PFOS as the major metabolite, and >32% yields have been observed. In Canadians, exposure to PreFOS was equivalent or greater than direct PFOS exposure prior to 2002. In most ocean water, PFOS is dominant to PreFOS, but in the oceans east of Greenland there may be more PreFOS than PFOS, consistent with the fact that whales and humans in this region also show evidence of substantial PreFOS exposure. Quantitative assessments of PFOS body-burdens coming from PreFOS are complicated by the fact that PreFOS partitions to the cellular fraction of blood, thus biomonitoring in serum under predicts PreFOS relative to PFOS. Many unknowns exist that prevent accurate modelling, thus analytical methods that can distinguish directly manufactured PFOS, from PFOS that has been biotransformed from PreFOS, should be applied in future human and environmental monitoring. Two new source tracking principles are presented and applied to human serum. 相似文献
A multi-level coastal wetland assessment strategy was applied to wetlands in the northern Gulf of Mexico (GOM) to evaluate the feasibility of this approach for a broad national scale wetland condition assessment (US Environmental Protection Agency’s National Wetlands Condition Assessment). Landscape-scale assessment indicators (tier 1) were developed and applied at the sub-watershed (12-digit hydrologic unit code (HUC)) level within the GOM coastal wetland sample frame with scores calculated using land-use maps and geographic information system. Rapid assessment protocols (tier 2), using a combination of data analysis and field work, evaluated metrics associated with landscape context, hydrology, physical structure, and biological structure. Intensive site monitoring (tier 3) included measures of soil chemistry and composition, water column and pore-water chemistry, and dominant macrophyte community composition and tissue chemistry. Relationships within and among assessment levels were evaluated using multivariate analyses with few significant correlations found. More detailed measures of hydrology, soils, and macrophyte species composition from sites across a known condition gradient, in conjunction with validation of standardized rapid assessment method, may be necessary to fully characterize coastal wetlands across the region. 相似文献
Forest road decommissioning is a pro-active mechanism for preventing future habitat degradation and for increasing the likelihood
of endangered salmonid survival in the western U.S. High implementation costs however preclude many desirable projects from
being undertaken, especially on federally owned land. Previous research and real-world applications have demonstrated the
cost savings potential of reusing aggregate recovered from forest roads during decommissioning. These cost savings can effectively
subsidize decommissioning projects, suggesting an economic benefit associated with improving environmental benefit. We present
a mixed integer, multiple objective formulation to identify the efficient trade-off surface between conflicting economic and
environmental criteria, where environmental benefit is defined as the hazard weighted length of roads decommissioned. We compare
nondominated frontiers identified with and without the opportunity to recycle aggregate. Our results suggest that aggregate
recycling promotes a synergistic relationship between cost savings (subsidy) and environmental performance, where subsidies
generally increase with increasing environmental performance. Effective subsidy values can reach 31% of total expenditure,
at the maximum level of environmental benefit. Transportation managers are therefore able to recover and reuse a nonrenewable
resource, while at the same time promoting economic and environmental efficiency. 相似文献
Environmental and Ecological Statistics - The presence and establishment of a tree species at a particular spatial location is influenced by multiple physiological and environmental filters such as... 相似文献
Ambio - A horizon scan was conducted to identify emerging and intensifying issues for biodiversity conservation in South Africa over the next 5–10 years. South African biodiversity... 相似文献
The tilapiine cichlids Oreochromis leucostictus and Tilapia zillii were introduced into Lake Naivasha, Kenya, in 1956. Previous studies on data collected to 1987 revealed they were persistent
following establishment, despite environmental variability and exploitation. Recent data, however, suggest this persistence
is under threat as data indicate some significant declines in aspects of their abundance since 1999. The influence of changes
in lake level, allodiversity and fishing effort on this decline was tested and showed that a decline in lake level was a significant
causal factor. The recent change in allodiversity, with the establishment and dominance of Cyprinus carpio in the fishery, was not significant on the catch per unit effort of O. leucostictus but was on T. zillii. Since 1999, catches of tilapiines in the fishery have been independent of fishing effort, contrary to between 1975 and 1987,
suggesting their management through application of fishery models may no longer be applicable. As it was anthropogenic-mediated
lake level changes that were mainly responsible for their decline, then lake management should focus on sustainable water
utilization that maximizes lake levels in accordance with the basin-wide water balance. 相似文献
The non-steroidal anti-inflammatory drug (NSAID) diclofenac is one of the most frequently studied as well as controversially discussed pharmaceutically active drug on the subject of its relevance to the environment. This study was conducted to assess the bioconcentration potential of diclofenac and its behavioral and biochemical effects in Daphnia magna. The bioconcentration factors of diclofenac determined after 48 h of aqueous exposure in Daphnia magna were 70.94 and 8.02 for the nominal exposure concentrations of 5 and 100 μg/L, respectively. Diclofenac exposure obviously decreased the filtration and ingestion rates of the daphnids. A significant increase of the acetylcholinesterase activity that was observed in this study indicates that diclofenac might not have neurobehavioral toxicity in Daphnia magna. Significant induction of malondialdehyde content is an indication of overproduction of reactive oxygen species leading to oxidative damage in daphnids after diclofenac exposure. Moreover, significant inhibition of the superoxide dismutase, catalase, and glutathione reductase activities implies that the antioxidant defense system of Daphnia magna was overwhelmed. Also, significant inhibition of glutathione s-transferase activity might point to the fact that the enzyme was not capable to detoxify diclofenac in Daphnia magna. These findings indicate that diclofenac can accumulate and consequently stimulate behavioral and biochemical disturbances in Daphnia magna.