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931.
932.
ABSTRACT The calls for greater racial equity also means cleaning up the air, water, and soil. Poor people needlessly suffer more in Louisville than the same low-income people in West Coast cites. If we adopted the same tough, environmental regulations as our West Coast Counterparts West Louisville would surely bloom instead of slowly die. The unfairness between black and white neighbourhoods is stark and vivid. As the great urbanist, Jane Jacobs, once said: “everyone hungers for a first class neighbourhood for both pride and dignity?…?nobody wants a second class neighborhood.” First class neighbourhoods are safe, healthy, sustainable, and prosperous. It is a human right; a Worldwide right. 相似文献
933.
Paramecium generates persistent shifts of the membrane potential of a few millivolts depending on its orientation with respect to the
gravity vector. The resulting potential-induced modulation of the speed of propulsion is called gravikinesis because it acts
to neutralize, fully or in part, sedimentation. Gravisensitivity is maximal at neutral orientation, i.e., in horizontally
swimming cells, when the gravitational force per unit membrane area is at minimum. Stimulus-response relationships and energetic
considerations show that sensing of the gravity vector by a nonspecialized, single-cell organism ranks among the most sensitive
mechanoreceptors known in nature.
Received: 15 December 1998 / Accepted: 18 February 1999 相似文献
934.
Bjørn Kløve Pertti Ala-aho Guillaume Bertrand Zuzana Boukalova Ali Ertürk Nico Goldscheider Jari Ilmonen Nusret Karakaya Hans Kupfersberger Jens Kvœrner Angela Lundberg Marta Mileusni? Agnieszka Moszczynska Timo Muotka Elena Preda Pekka Rossi Dmytro Siergieiev Josef Šimek Przemys?aw Wachniew Vadineanu Angheluta Anders Widerlund 《Environmental Science & Policy》2011,14(7):770-781
Groundwater dependent ecosystems (GDEs) include valuable ecosystems such as springs, wetlands, rivers, lakes and lagoons. The protection of these systems and services they provide is highlighted by international agreements, i.e. Ramsar convention on wetlands, and regional legislation, i.e. the European Water Framework Directive. Groundwater provides water, nutrients and a relatively stable temperature. However, the role of groundwater in surface ecosystems is not fully understood. The ecosystem can depend on groundwater directly or indirectly, and the reliance can be continuous, seasonal or occasional. This has implications for the vulnerability of ecosystems, as some may be easily affected by external pressure. Conceptual models and quantitative assessments of how groundwater interacts with the environment are needed. GDEs are also threatened by different land use activities and climate change. Hence, we need to understand how GDEs are affected by changes in groundwater quantity and quality, as severe groundwater changes have been observed in many regions. This study examines key aspects of GDEs (hydrogeology, geochemistry and biodiversity) in order to improve conceptual understanding of the role of groundwater in such ecosystems. The status and baseline of different types of GDEs are discussed, with particular emphasis on past evidence of environmental change and potential thresholds and threats in GDEs in various parts of Europe with different land use, climate and geology. 相似文献
935.
Groundwater dependent ecosystems. Part II. Ecosystem services and management in Europe under risk of climate change and land use intensification 总被引:1,自引:0,他引:1
Bjørn Kløve Andrew Allan Guillaume Bertrand Elzbieta Druzynska Ali Ertürk Nico Goldscheider Sarah Henry Nusret Karakaya Timo P. Karjalainen Phoebe Koundouri Hans Kupfersberger Jens Kvœrner Angela Lundberg Timo Muotka Elena Preda Manuel Pulido-Velazquez Peter Schipper 《Environmental Science & Policy》2011,14(7):782-793
Groundwater in sufficient amounts and of suitable quality is essential for potable water supplies, crop irrigation and healthy habitats for plant and animal biocenoses. The groundwater resource is currently under severe pressure from land use and pollution and there is evidence of dramatic changes in aquifer resources in Europe and elsewhere, despite numerous policy measures on sustainable use and protection of groundwater. Little is known about how such changes affect groundwater dependent ecosystems (GDEs), which include various aquatic and terrestrial ecosystems above ground and inside the aquifer. Future management must take this uncertainty into account. This paper focuses on multiple aspects of groundwater science, policy and sustainable management. Examples of current management methods and practices are presented for selected aquifers in Europe and an assessment is made of the effectiveness of existing policies such as the European Water Framework Directive and the Habitat Directive in practice and of how groundwaters and GDEs are managed in various conditions. The paper highlights a number of issues that should be considered in an integrated and holistic approach to future management of groundwater and its dependent ecosystems. 相似文献
936.
937.
Colonization studies may function as natural experiments and have the potential of addressing important questions about community assembly. We studied colonization for a guild of epiphytic lichens in a former treeless heathland area of 170 km2 in southwest Norway. We investigated if epiphytic lichen species richness and composition on aspen (Populus tremula) trees corresponded to a random draw of lichen individuals from the regional species pool. We compared lichen communities of isolated young (55-120 yr) and old (140-200 yr) forest patches in the heathland area to those of aspen forest in an adjacent reference area that has been forested for a long time. All thalli (lichen bodies) of 32 selected lichen species on trunks of aspen were recorded in 35 aspen sites. When data for each site category (young, old, and reference) were pooled, we found the species richness by rarefaction to be similar for reference sites and old sites, but significantly lower for young sites. The depauperated species richness of young sites was accompanied by a skew in species composition and absence of several species that were common in the reference sites. In contrast, genetic variation screened with neutral microsatellite markers in the lichen species Lobaria pulmonaria showed no significant differences between site categories. Our null hypothesis of a neutral species assembly in young sites corresponding to a random draw from the regional species pool was rejected, whereas an alternative hypothesis based on differences in colonization capacity among species was supported. The results indicate that for the habitat configuration in the heathland area (isolated patches constituting < 0.4% of the area) lichen communities may need a colonization time of 100-150 yr for species richness to level off, but given enough time, isolation will not affect species richness. We suggest that this contradiction to expectations from classical island equilibrium theory results from low extinction rates. 相似文献
938.
A note on a non-stationary point source spatial model 总被引:1,自引:0,他引:1
Mark D. Ecker Victor De Oliveira Hans Isakson 《Environmental and Ecological Statistics》2013,20(1):59-67
A point source, non-stationary covariance structure model is proposed, having only one additional parameter over a standard, stationary covariance structure, spatial model. Additionally, the proposed model is demonstrated to fit better than the three extra parameter, point source, non-stationary spatial model proposed by Ecker and De Oliveira (Commun Stat Theory Methods 37:2066–2078, 2008). The proposed model is fit from a Bayesian perspective and illustrated using a house sales dataset from Cedar Falls, Iowa. 相似文献
939.
Duan Shuhuai Geng Zhihui Hans M. Gregersen Kenneth N. Brooks Peter F Ffolliott 《Journal of the American Water Resources Association》2001,37(3):585-594
ABSTRACT: Watersheds above the Miyun reservoir, a principal source of surface water for Beijing, are designated to be managed for water production, but under the principle of multiple use. Because of the scarcity of arable land, these watersheds cannot be managed only for drinking water. Efforts are under way to reduce sediment delivery, improve the quality of water entering Miyun reservoir, and improve the welfare of watershed inhabitants. An economic appraisal of a watershed management project for the 3,298‐ha Shixia watershed above the Miyun reservoir, indicates a 24 percent economic rate of return on the investment made in the project. The net present value (NPV) of the project, calculated at a discount rate of 10 percent, is approximately US$3.49 million. Sensitivity analyses indicate that a doubling of labor costs lowers the NPV to US$2.07 million and a 10 percent decrease in benefits lowered the NPV to US$2.87. It is concluded that the implementation of conservation practices on the Shixia Demonstration Watershed represent an economically efficient use of resources. 相似文献
940.
Konstantinos Feidantsis Hans O. P?rtner Antigoni Lazou Basile Kostoglou Basile Michaelidis 《Marine Biology》2009,156(4):797-809
Tolerance to a changing climate regime and persistence in the natural environment depends on the limited capacity to acclimate
to changing temperatures. The present study aimed to identify and characterize thermal limits of the Mediterranean fish Sparus aurata as well as the processes providing heat protection during exposure to high temperatures. Processes studied included heat
shock protein expression, protein kinase activity and metabolic adjustments. Molecular responses were addressed through the
expression of Hsp70 and Hsp90 and the phosphorylation of stress-activated protein kinases, p38 mitogen-activated protein kinase
(p38 MAPK) and cJun-N-terminal kinases (JNKs). Thermal impacts on metabolic capacities were assessed by studying the maximum
activities of citrate synthase (CS), malate dehydrogenase (MDH) and 3-hydroxyacyl CoA dehydrogenase (HOAD) as well as pyruvate
kinase (PK) and lactate dehydrogenase (L-LDH). The expression of Hsp70 and hsp90 was activated when the fish were exposed
to temperatures beyond 20°C. Increased phosphorylation of p38 MAPK and JNKs indicated the parallel activation of MAPK signaling
cascades and the potential involvement of MAPKs in the induction of Hsp genes. Exposure to extreme temperatures beyond 24°C
caused an increase in the enzymatic activity of PK and LDH indicating an enhanced glycolytic potential. 相似文献