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River damming provides a dominant human impact on river environments worldwide, and while local impacts of reservoir flooding
are immediate, subsequent ecological impacts downstream can be extensive. In this article, we assess seven research strategies
for analyzing the impacts of dams and river flow regulation on riparian ecosystems. These include spatial comparisons of (1)
upstream versus downstream reaches, (2) progressive downstream patterns, or (3) the dammed river versus an adjacent free-flowing
or differently regulated river(s). Temporal comparisons consider (4) pre- versus post-dam, or (5) sequential post-dam conditions.
However, spatial comparisons are complicated by the fact that dams are not randomly located, and temporal comparisons are
commonly limited by sparse historic information. As a result, comparative approaches are often correlative and vulnerable
to confounding factors. To complement these analyses, (6) flow or sediment modifications can be implemented to test causal
associations. Finally, (7) process-based modeling represents a predictive approach incorporating hydrogeomorphic processes
and their biological consequences. In a case study of Hells Canyon, the upstream versus downstream comparison is confounded
by a dramatic geomorphic transition. Comparison of the multiple reaches below the dams should be useful, and the comparison
of Snake River with the adjacent free-flowing Salmon River may provide the strongest spatial comparison. A pre- versus post-dam
comparison would provide the most direct study approach, but pre-dam information is limited to historic reports and archival
photographs. We conclude that multiple study approaches are essential to provide confident interpretations of ecological impacts
downstream from dams, and propose a comprehensive study for Hells Canyon that integrates multiple research strategies. 相似文献
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Volunteer monitoring of natural resources is promoted for its ability to increase public awareness, to provide valuable knowledge, and to encourage policy change that promotes ecosystem health. We used the case of volunteer macroinvertebrate monitoring (VMM) in streams to investigate whether the quality of data collected is correlated with data use and organizers' perception of whether they have achieved these outcomes. We examined the relation between site and group characteristics, data quality, data use, and perceived outcomes (education, social capital, and policy change). We found that group size and the degree to which citizen groups perform tasks on their own (rather than aided by professionals) positively correlated with the quality of data collected. Group size and number of years monitoring positively influenced whether a group used their data. While one might expect that groups committed to collecting good-quality data would be more likely to use it, there was no relation between data quality and data use, and no relation between data quality and perceived outcomes. More data use was, however, correlated with a group's feeling of connection to a network of engaged citizens and professionals. While VMM may hold promise for bringing citizens and scientists together to work on joint conservation agendas, our data illustrate that data quality does not correlate with a volunteer group's desire to use their data to promote regulatory change. Therefore, we encourage scientists and citizens alike to recognize this potential disconnect and strive to be explicit about the role of data in conservation efforts. 相似文献
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Stream fish bioassessment methods assume that fish assemblages observed in sample sites reflect responses to local stressors, but fish assemblages are influenced by local factors as well as regional dispersal to and from connected streams. We hypothesized that fish movement to and from refugia and source populations in connected rivers (i.e., riverine dispersal) would weaken or decouple relations between fish community metrics and local environmental conditions. We compared fish-environment relations between streams that flow into large rivers (mainstem tributaries) and streams that lack riverine confluences (headwater tributaries) at multiple spatial grains using data from the USEPA's Environmental Monitoring and Assessment Program in the mid-Atlantic highlands, USA (n = 157 sites). Headwater and mainstem tributaries were not different in local environmental conditions, but showed important differences in fish metric responses to environmental quality gradients. Stream sites flowing into mainstem channels within 10 fluvial km showed consistently weaker relations to local environmental conditions than stream sites that lacked such mainstem connections. Moreover, these patterns diminished at longer distances from riverine confluences, consistent with the hypothesis of riverine dispersal. Our results suggest that (1) the precision of fish bioassessment metrics may be improved by calibrating scoring criteria based on the spatial position of sites within stream networks and (2) the spatial grain of fish bioassessment studies may be manipulated to suit objectives by including or excluding fishes exhibiting riverine dispersal. 相似文献
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将源分类家庭生物有机垃圾同秸秆按质量比10:1混合后进行堆肥处理,应用气相色谱-质谱联用仪(GC-MS)按照U.S.EPA 8270方法对生物有机垃圾及其堆肥产品中16种PAHs进行分析测试,比较生物有机垃圾及其堆肥产品中16种PAHs含量、分布及生物降解率,评估堆肥产品PAHs农田风险,综合论述影响家庭有机垃圾堆肥过程中PAHs降解因素,为生物有机垃圾堆肥农田利用提供依据.结果表明,源分类家庭生物有机垃圾及其堆肥产品中∑PAH16化合物含量分别为2.19和1.96mg/ks(以干重计,下同),其中萘、芴、菲、荧蒽含量相对较高,占总量的79.76%和81.76%,这4种有机物的苯环在2-3之间,属于易降解非致癌物质,在农田施用中易被降解;在生物垃圾堆肥过程中∑PAH16的生物降解率为25.88%,堆肥后产品PAHs含量符合农田使用标准. 相似文献
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Dynamic Games in the Economics and Management of Pollution 总被引:1,自引:0,他引:1
Steffen Jørgensen Guiomar Martín-Herrán Georges Zaccour 《Environmental Modeling and Assessment》2010,15(6):433-467
The paper provides a survey of the literature which utilizes dynamic state-space games to formulate and analyze intertemporal, many decision-maker problems in the economics and management of pollution. 相似文献
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Cornelia Meinert Emma Schymanski Eberhard Küster Ralph Kühne Gerrit Schüürmann Werner Brack 《Environmental science and pollution research international》2010,17(4):885-897