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Danny Reible David Lampert David Constant Robert D. Mutch Jr. Yuewei Zhu 《补救:环境净化治理成本、技术与工艺杂志》2006,17(1):39-53
An active capping demonstration project in Washington, D.C., is testing the ability to place sequestering agents on contaminated sediments using conventional equipment and evaluating their subsequent effectiveness relative to conventional passive sand sediment caps. Selected active capping materials include: (1) AquaBlokTM, a clay material for permeability control; (2) apatite, a phosphate mineral for metals control; (3) coke, an organic sequestration agent; and (4) sand material for a control cap. All of the materials, except coke, were placed in 8,000‐ft test plots by a conventional clamshell method during March and April 2004. Coke was placed as a 1.25‐cm layer in a laminated mat due to concerns related to settling of the material. Postcap sampling and analysis were conducted during the first, sixth, and eighteenth months after placement. Although postcap sampling is expected to continue for at least an additional 24 months, this article summarizes the results of the demonstration project and postcap sampling efforts up to 18 months. Conventional clamshell placement was found to be effective for placing relatively thin (six‐inch) layers of active material. The viability of placing high‐value or difficult‐to‐place material in a controlled manner was successfully demonstrated with the laminated mat. Postcap monitoring indicates that all cap materials effectively isolated contaminants, but it is not yet possible to differentiate between conventional sand and active cap layer performance. Monitoring of the permeability control layer indicated effective reductions in groundwater seepage rates through the cap, but also showed the potential for gas accumulation and irregular release. All of the cap materials show deposition of new contaminated sediment onto the surface of the caps, illustrating the importance of source control in maintaining sediment quality. © 2006 Wiley Periodicals, Inc. 相似文献
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Whereas past research has treated co-management of common pool resources as if villagers and project implementing authorities
were the only relevant actors, numerous external factors beyond the control of these two partners create barriers to successful
co-management. This paper draws on discussions with Forest Department officials to examine the influence of these forces on
the outcomes of Joint Forest Management (JFM) in Tamil Nadu, India. An empirical inquiry into the operational aspects of JFM
indicates the important roles of political parties, powerful people, and other state institutions and functionaries as well
as the flow of foreign funding. Further, the strong demand by local people for socio-economic development interventions as
opposed to improvement of degraded forests belittles the role of the Forest Department relative to other departments. Numerous
other conditioning factors and relationships are explored. The authors call for reforms in public governance to allow better
participation of all the actors involved for this participatory management approach to succeed and sustain. 相似文献
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Although stewardship has been widely defined and used in environmental management and planning, there is a dearth of studies
that describe how the lay public perceives this concept. A national sample of residents in 14 states who live near DOE nuclear
facilities were interviewed to delineate public understanding and awareness of the stewardship program of the U.S. Department
of Energy (DOE). This study discusses the findings of the survey and discusses how institutional trust influences public participation
and resident’s choices of potential stewards. Almost 40% of the respondents could not define stewardship; those who did, believed
that ‘responsibility,’ ‘management,’ and ‘accountability’ are key elements of stewardship. In addition, about a third of the
respondents identified Federal groups and the DOE as potential stewards.
Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue 相似文献
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Environmental factors have long been shown to influence species distributions, with range limits often resulting from environmental
stressors exceeding organism tolerances. However, these abiotic factors may differentially affect species with multiple life-history
stages. Between September 2004 and January 2006, the roles of temperature and nutrient availability in explaining the southern
distributions of two understory kelps, Pterygophora californica and Eisenia arborea (Phaeophyceae, Laminariales), were investigated along the coast of California, USA and the Baja California Peninsula, Mexico,
by limiting either: (a) tissue nitrogen uptake and storage by adult sporophytes during periods of elevated temperature, and/or
(b) production of embryonic sporophytes by microscopic gametophytes. Results suggest that while adult sporophytes of both
species are tolerant of high temperatures and low nutrients, reproduction by their microscopic stages is not. Specifically,
while E. arborea produced embryonic sporophytes at both 12 and 18°C, temperatures commonly observed throughout the southern portion of its
range, P. californica produced sporophytes at 12 but not at 18°C. As a result, it appears that the southern distribution of P. californica, which ends in northern Baja California, Mexico, may be limited by temperature acting on its microscopic stages. In contrast,
the ability of E. arborea’s microscopic and adult stages to tolerate elevated temperatures allows it to persist in the warmer southern waters of Baja
California, as well as to the north along the California coast where both species co-occur. 相似文献
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