The coming century is predicted to feature enhanced climatic variability, including increased frequency, intensity, and duration of extreme climatic events. Ecologists are faced with the critical challenge of anticipating potentially nonlinear ecosystem responses to these changes. High-resolution paleoecological data sets that capture past ecosystem responses to climate variability provide valuable long-term perspectives on the sensitivity of ecosystems to climate-forced state shifts. We used a suite of paleoecological analyses at Titus Bog in northwestern Pennsylvania, USA, to test the hypothesis that the development and expansion of floating peatlands in kettlehole basins represents a threshold response to hydroclimate variability. In contrast with expectations of gradual autogenic peat mat expansion, our results indicate that peat mat expansion at Titus Bog was highly episodic and occurred in three distinct pulses centered on 800, 650, and 400 cal yr BP. Each of these expansion events coincided with or immediately followed decadal-to-mutlidecadal droughts recorded in regional paleoclimate reconstructions. These patterns indicate that peatland development in kettlehole basins can follow nonlinear trajectories, with episodes of rapid advancement triggered by climatic forcing. Future climate changes may increase the likelihood of peatland expansion in kettlehole basins, potentially leading to abrupt changes in adjacent lake ecosystems. 相似文献
Using an innovative, two-stage process to remediate uranium-contaminated soils, researchers at Los Alamos National Laboratory's (LANL's) Technical Area 33 (TA-33) successively reduced 218 cubic yards of contaminated soil to approximately 30 gallons of leachate solution and resins. In the first step, the contaminated soil is separated from the clean soil using the Thermo Nuclean (a division of the Thermo NUtech company) Segmented Gate System (SGS). Contaminated soil proceeds via conveyor belt to a separate storage bin to await further processing, while uncontaminated soil is returned to its original location. From the 218 cubic yards of soil excavated from the test site at TA-33, only seven cubic yards were found to contain uranium contamination above the criterion release limit, yielding an initial waste volume reduction of 97 percent. Using the containerized vat leaching (CVL) method, a technique borrowed from the mining industry, the uranium was then removed from the reduced volume of contaminated soil. This article describes the two processes and analyzes potential cost savings based on different disposal and storage options. 相似文献
This paper extends previous research assessing the effects of environmental pollution on property values, and the specific issue of information disclosure requirements on future real estate transactions. Given that various information disclosure requirements were imposed in most US states during the 1990s, it is important to begin to understand their anticipated effects. Using a case of soil contamination in Corpus Christi, TX, USA, this paper applies the contingent valuation method using telephone survey data to investigate the effect of a split-sample information disclosure treatment concerning soil contamination on the willingness to pay of potential home buyers. The authors apply a mixture modelling approach to better explain the effect of the information disclosure requirement. 相似文献
After briefly reviewing key resilience engineering perspectives and summarising some green infrastructure (GI) tools, we present the contributions that GI can make to enhancing urban resilience and maintaining critical system functionality across complex integrated social–ecological and technical systems. We then examine five key challenges for the effective implementation of GI that include (1) standards; (2) regulation; (3) socio-economic factors; (4) financeability; and (5) innovation. We highlight ways in which these challenges are being dealt with around the world, particularly through the use of approaches that are both context appropriate and socially inclusive. Although progress surmounting these challenges has been made, more needs to be done to ensure that GI approaches are inclusive and appropriate and feature equally alongside more traditional ‘grey’ infrastructure in the future of urban resilience planning. This research was undertaken for the Resilience Shift initiative to shift the approach to resilience in practice for critical infrastructure sectors. The programme aims to help practitioners involved in critical infrastructure to make decisions differently, contributing to a safer and better world. 相似文献
Preliminary mineral magnetic results from a pilot project investigating the suitability of roadside tree leaves as depositories
of vehicular pollution are presented. Tree leaf surfaces (Lime: Tilia europaea; Sycamore: Acer pseudoplatanus) at four roadside and one woodland location in Wolverhampton, UK, have been monitored (July 2003 to November 2003). Mineral
magnetic technologies have revealed spatial variations of particulate pollution concentration throughout the conurbation and
data analysis indicates that magnetic concentration parameters are suitable proxies for fine particulate pollution, which
are particularly hazardous to health. Site-specific traffic management and associated vehicle behaviour appear to be chiefly
responsible for the magnetic concentration differences between sites. Magneto-biomonitoring in this way allows the high-resolution
spatial mapping of particulate matter (PM) pollution, which may also benefit epidemiology in better assessing exposure to
vehicular-derived particulates. Given the speed, measurement sensitivity and non-destructive nature of the technique, it is
proposed that this low-cost approach offers some advantages over centralised monitoring stations to monitor urban roadside
particulate pollution. 相似文献
Objective: The objective of this study was to investigate vehicle factors associated with child restraint tether use and misuse in pickup trucks and evaluate 4 labeling interventions designed to educate consumers on proper tether use.
Methods: Volunteer testing was performed with 24 subjects and 4 different pickup trucks. Each subject performed 8 child restraint installations among the 4 pickups using 2 forward-facing restraints: a Britax Marathon G4.1 and an Evenflo Triumph. Vehicles were selected to represent 4 different implementations of tether anchors among pickups: plastic loop routers (Chevrolet Silverado), webbing routers (Ram), back wall anchors (Nissan Frontier), and webbing routers plus metal anchors (Toyota Tundra). Interventions included a diagram label, Quick Response (QR) Code linked to video instruction, coordinating text label, and contrasting text tag.
Results: Subjects used the child restraint tether in 93% of trials. However, tether use was completely correct in only 9% of trials. An installation was considered functional if the subject attached the tether to a tether anchor and had a tight installation (ignoring routing and head restraint position); 28% of subjects achieved a functional installation. The most common installation error was attaching the tether hook to the anchor/router directly behind the child restraint (near the top of the seatback) rather than placing the tether through the router and attaching it to the anchor in the adjacent seating position. The Nissan Frontier, with the anchor located on the back wall of the cab, had the highest rate of correct installations but also had the highest rate of attaching the tether to components other than the tether anchor (seat adjustor, child restraint storage hook, around head restraint). None of the labeling interventions had a significant effect on correct installation; not a single subject scanned the QR Code to access the video instruction. Subjects with the most successful installations spent extensive time reviewing the vehicle manuals.
Conclusion: Current implementations of tether anchors among pickup trucks are not intuitive for child restraint installations, and alternate designs should be explored. Several different labeling interventions were ineffective at achieving correct tether use in pickup trucks. 相似文献
A demonstration project in Oregon examined the feasibility of combining Federal environmental monitoring surveys. An integrated approach should remove duplication of effort and reduce the possibility of providing apparently conflicting information to policy makers and the public. Data collection teams made photo interpretation measurements and on-site soil/vegetation/animal observations at locations that were selected from the Forest Inventory and Analysis (FIA), National Forest System (NFS) Region 6, and National Resource Inventory (NRI) surveys in a six-county area in Northern Oregon. The project demonstrated the feasibility of conducting a combined FIA/NFS/NRI survey and suggests an approach that will preserve the utility of the critical historical information from these surveys. We suggest a framework for estimating the extent of forest and range land that explains FIA/NRI differences and provides a common basis for both surveys. We suggest indicator and protocol criteria that will allow consistent national and regional estimates over all vegetation types, and stress the importance of including measurement repeatability in the design of the combined survey. 相似文献