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131.
Len Wright Paul Chinowsky Kenneth Strzepek Russell Jones Richard Streeter Joel B. Smith Jean-Marc Mayotte Anthony Powell Lesley Jantarasami William Perkins 《Mitigation and Adaptation Strategies for Global Change》2012,17(8):939-955
We assessed the potential impacts of increased river flooding from climate change on bridges in the continental United States. Daily precipitation statistics from four climate models and three greenhouse gas (GHG) emissions scenarios (A2, A1B, and B1) were used to capture a range of potential changes in climate. Using changes in maximum daily precipitation, we estimated changes to the peak flow rates for the 100-year return period for 2,097 watersheds. These estimates were then combined with information from the National Bridge Inventory database to estimate changes to bridge scour vulnerability. The results indicate that there may be significant potential risks to bridges in the United States from increased precipitation intensities. Approximately 129,000 bridges were found to be currently deficient. Tens of thousands to more than 100,000 bridges could be vulnerable to increased river flows. Results by region vary considerably. In general, more bridges in eastern areas are vulnerable than those in western areas. The highest GHG emissions scenarios result in the largest number of bridges being at risk. The costs of adapting vulnerable bridges to avoid increased damage associated with climate change vary from approximately $140 to $250 billion through the 21st century. If these costs were spread out evenly over the century, the annual costs would be several billion dollars. The costs of protecting the bridges against climate change risks could be reduced by approximately 30% if existing deficient bridges are improved with riprap. 相似文献
132.
The U.N. Framework Convention on Climate Change (FCCC) allows for the joint implementation (JI) of measures to mitigate the emissions of greenhouse gases. The concept of JI refers to the implementation of such measures in one country with partial or full financial and/or technical support from another country, potentially fulfilling some of the supporting country's emission-reduction commitment under the FCCC. At present, all JI transactions are voluntary, and no country has claimed JI credit against existing FCCC commitments. Nevertheless, JI could have important implications for both the economic efficiency and the international equity of the implementation of the FCCC. This paper discusses some of the information needs of JI projects and seeks to clarify some of the common assumptions and arguments about JI. Issues regarding JI are distinguished according to those that are specific to JI and those that apply to JI as well as other types of regimes and transactions. The focus is on the position of developing countries and their potential risks and benefits regarding JI. 相似文献
133.
Rachael Hunter Robert Lane John Day Joel Lindsey Jason Day Montgomery Hunter 《Environmental management》2009,44(5):865-873
The relationship between nutrient removal and loading rate was examined using data from five forested wetlands in Louisiana
that have received secondarily treated effluent from 3 to 60 years. Loading rates ranged from 0.65 to 26.80 g/m2/yr for total nitrogen and 0.18 to 8.96 g/m2/yr for total phosphorus. At loading rates below 20 g/m2/yr, total nitrogen concentrations in surface waters of Louisiana forested wetlands were reduced to background concentrations
(i.e., ≤3 mg/l). Similarly, at loading rates below 2 g/m2/yr, total phosphorus concentrations were also generally reduced to background concentrations (i.e., ≤1 mg/l). These data
demonstrate that freshwater forested wetlands can reduce nutrient concentrations in treated effluent to background concentrations
present in relatively undisturbed wetlands. An understanding of the relationship between loading rates and nutrient removal
in natural wetlands is important, particularly in Louisiana where discharges of fresh water are being used in ecosystem restoration. 相似文献
134.
A research study was performed to determine the fats, oil, and grease (FOG) removal efficiency of internal flow-based grease interceptors (FGI). A passive-flow and a mechanical-flow FGI unit were tested and their performance was compared to an external retention-based grease interceptor (RGI). Experiments involved multiple parameters including three oil/water emulsion strengths, two influent liquid temperatures, and two flow rates. Overall, the RGI achieved approximately 80% FOG removal and the FGIs removed less than 50% under the tested conditions. One exception occurred during the passive FGI testing during which removal reached approximately 80%. This increased efficiency was likely due to the relatively weak emulsion exhibiting significantly large FOG globules. The FOG removal efficiency decreased with increased temperature because of increased breakage of FOG globules at the elevated temperature. These results suggest that emulsion strength significantly affects FOG removal efficiency of FGIs and should be considered in future manufacturer testing protocol. 相似文献
135.
136.
Relationships among Isolated Wetland Size, Hydroperiod, and Amphibian Species Richness: Implications for Wetland Regulations 总被引:6,自引:0,他引:6
Joel W. Snodgrass †‡ Mark J. Komoroski † A. Lawrence Bryan JR. † Joanna Burger 《Conservation biology》2000,14(2):414-419
Abstract: Wetland development within the United States is regulated primarily by size. Decisions concerning wetland destruction or conservation are therefore based in part on three inherent assumptions: (1) small wetlands contain water for short portions of the year; (2) small wetlands support few species; and (3) species found in small wetlands are also found in larger wetlands. We tested these assumptions using data on wetland size, relative hydroperiod (drying scores), and relative species richness of amphibians in depression wetlands of the southeastern United States. We found a significant (p = 0.03) but weak (r2 = 0.05) relationship between hydroperiod and wetland size and no relationship (p = 0.48) between amphibian species richness and wetland size. Furthermore, synthetic models of lentic communities predict that short-hydroperiod wetlands support a unique group of species. Empirical investigations support this prediction. Our results indicate that hydroperiod length should be included as a primary criterion in wetland regulations. We advocate a landscape approach to wetlands regulation, focused in part on conserving a diversity of wetlands that represent the entire hydroperiod gradient. 相似文献
137.
Constructed wetlands are widely used for wastewater treatment, but there is little information on processes affecting their performance in cold climates, effects of plants on seasonal performance, or plant selection for cold regions. We evaluated the effects of three plant species on seasonal removal of dissolved organic matter (OM) (measured by chemical oxygen demand and dissolved organic carbon) and root zone oxidation status (measured by redox potential [Eh] and sulfate [SO4(2-)]) in subsurface-flow wetland (SSW) microcosms. A series of 20-d incubations of simulated wastewater was conducted during a 28-mo greenhouse study at temperatures from 4 to 24 degrees C. Presence and species of plants strongly affected seasonal differences in OM removal and root zone oxidation. All plants enhanced OM removal compared with unplanted controls, but plant effects and differences among species were much greater at 4 degrees C, during dormancy, than at 24 degrees C, during the growing season. Low temperatures were associated with decreased OM removal in unplanted controls and broadleaf cattail (Typha latifolia L.) microcosms and with increased removal in beaked sedge (Carex rostrata Stokes) and hardstem bulrush [Schoenoplectus acutus (Muhl. ex Bigelow) A. & D. L?ve var. acutus] microcosms. Differences in OM removal corresponded to species' apparent abilities to increase root zone oxygen supply. Sedge and bulrush significantly raised Eh values and SO4(2-) concentrations, particularly at 4 degrees C. These results add to evidence that SSWs can be effective in cold climates and suggest that plant species selection may be especially important to optimizing SSW performance in cold climates. 相似文献
138.
139.
Samuel A. Oyewole Joel M. Haight Andris Freivalds David J. Cannon Ling Rothrock 《Journal of Loss Prevention in the Process Industries》2010,23(5):585-593
This paper provides an analytical background for the development of an effective safety intervention program with the aim of minimizing incident rates. Safety intervention data were collected from the environmental health and safety department of an American-owned oil company in the Niger-Delta region of Nigeria. A safety model was developed to determine the safety intervention factors and interactions which minimize incident rates, with the aim of predicting a better resource allocation strategy. Five main safety intervention factors (factor A: leadership and accountability; factor B: qualification selection and pre-job; factor C: employee engagement and planning; factor D: work in progress; factor E: evaluation, measurement and verification) were highlighted and investigated to show their effects on incident rate performance. Analysis of variance test showed that four safety factors (A, C, D, and E) were significant. Statistical techniques such as response surface design plots were used to determine the resource allocation method. The developed safety model recommended the allocation of 16.66% of the available resources to the significant safety intervention activities in order to achieve the desirable incident rate. In order to reap the benefits of this research, it will be important to concentrate more efforts and resources on significant factors which have positive impacts in minimizing incident rates. 相似文献
140.
We surveyed patterns in the relative abundance and size structure of the sea stars Pisaster ochraceus and Evasterias troschelii in five habitat types of varying structural complexity and prey availability (sand/cobble, boulder, and rocky intertidal; pilings; and floating docks) in Puget Sound and the San Juan Islands, Washington. For both species, small sea stars were most abundant in the most structurally complex habitat type (boulder), where they occurred almost exclusively under boulders during low tide. Larger individuals became more abundant as structural complexity decreased, occurring more frequently in open habitat types (rocky shores, pilings, and docks) known to have greater abundances of prey resources. Gull foraging observations and experiments demonstrated that exposed small sea stars of both species were highly vulnerable to predation, suggesting that small sea stars require structural complexity (crevice microhabitat) as a predation refuge. Large sea stars, once attaining a size refuge from predation, appear to migrate to more exposed habitat types with more abundant food resources. These results suggest parallel ontogenetic habitat shifts in two co-occurring consumer species related to a shared predation risk at early life stages and demonstrate how the relative importance of top-down and bottom-up processes may differ with ontogeny. 相似文献