The role of interbasin groundwater transfers in geologically complex terranes,demonstrated by the Great Basin in the western United States     

Stephen T. Nelson  Alan L. Mayo 《Hydrogeology Journal》2014,22(4):807-828

In the Great Basin, USA, bedrock interbasin flow is conceptualized as the mechanism by which large groundwater fluxes flow through multiple basins and intervening mountains. Interbasin flow is propounded based on: (1) water budget imbalances, (2) potential differences between basins, (3) stable isotope evidence, and (4) modeling studies. However, water budgets are too imprecise to discern interbasin transfers and potential differences may exist with or without interbasin fluxes. Potentiometric maps are dependent on conceptual underpinnings, leading to possible false inferences regarding interbasin transfers. Isotopic evidence is prone to non-unique interpretation and may be confounded by the effects of climate change. Structural and stratigraphic considerations in a geologically complex region like the Great Basin should produce compartmentalization, where increasing aquifer size increases the odds of segmentation along a given flow path. Initial conceptual hypotheses should explain flow with local recharge and short flow paths. Where bedrock interbasin flow is suspected, it is most likely controlled by diversion of water into the damage zones of normal faults, where fault cores act as barriers. Large-scale bedrock interbasin flow where fluxes must transect multiple basins, ranges, and faults at high angles should be the conceptual model of last resort.  相似文献   

Quantification of Vibrio vulnificus in an Estuarine Environment: a Multi-Year Analysis Using QPCR     

Jennifer J. Wetz  A. Denene Blackwood  J. Stephen Fries  Zachary F. Williams  Rachel T. Noble 《Estuaries and Coasts》2014,37(2):421-435

Using a refined quantitative polymerase chain reaction assay, we compared surface and bottom water concentrations of Vibrio vulnificus with total Vibrio spp. concentrations, fecal indicator bacteria (Escherichia coli and Enterococcus sp.), and environmental parameters (salinity, temperature, chlorophyll a, and turbidity) over 4 years at a mesohaline site in the Neuse River Estuary in North Carolina. V. vulnificus was not detected when water temperature was below 20 °C and 93 % of positive samples were from salinities 10–20 psu. V. vulnificus was detected in 50 % of summer samples with peak concentrations in summer bottom waters. Significant positive correlations for V. vulnificus and temperature, salinity, and bacterial group abundance were found. Significant negative correlations with chlorophyll a were also observed. Interannual comparisons indicated a significant decrease in mean V. vulnificus since 2005, corresponding with increasing salinity due to severe drought conditions in 2007 and 2008. Total Vibrio spp. abundance also decreased in 2007 but returned to the previously observed abundance by 2008. Although a significant positive relationship between total Vibrio spp. and V. vulnificus was documented, interannual comparisons indicate that total Vibrio spp. densities may not be indicative of V. vulnificus in all environmental conditions and that long-term drought conditions may alter community composition.  相似文献   

Integrated stratigraphy and palaeoenvironment of the P/E boundary interval, Rakhi Nala section, Indus Basin (Pakistan)     

Muhammad Hanif  Malcolm B. Hart  Stephen T. Grimes  Melanie J. Leng 《Arabian Journal of Geosciences》2014,7(1):323-339

Marine sedimentary section across the Paleocene/Eocene (P/E) boundary interval is preserved in the Dungan Formation (Lower Indus Basin), Pakistan. Four dinoflagellate zones in the P/E interval of the Rakhi Nala section (Lower Indus Basin) are identified and correlated. The quantitative analysis of the dinoflagellate cyst assemblages together with geochemical data are used to reconstruct the palaeoenvironment across the P/E interval. The dinocyst assemblages allow the local correlation of the Dungan Formation (part) of the Sulaiman Range with the Patala Formation (part) of the Upper Indus Basin and global correlation of the Zone Pak-DV with the Apectodinium acme Zone of the Northern and Southern hemispheres. The onset of the carbon isotopic excursion (CIE) associated with Paleocene Eocene Thermal Maximum (PETM) is used globally to identify the P/E boundary. The CIE for the total organic carbon (fine fraction) δ¹³C_FF is of a magnitude of ?1.7‰ is recorded for the first time in the Indus Basin. The Apectodinium acme precedes and straddles the onset of the CIE in the Indus Basin. This Apectodinium acme is also accompanied by a planktonic and benthonic foraminifera “barren zone.” The CIE in the Indus Basin, coupled with the changes in the dinocyst distribution and the benthonic and planktonic foraminifera assemblages, provides evidence of the changes associated with the PETM in this little-known part of the world. The benthonic foraminiferal assemblage indicates bathyal environment of deposition at the time of P/E boundary interval; the presence of dominantly open marine dinoflagellates and high planktonic foraminiferal ratio suggest that the water column at this site was well connected with the rest of the Tethys.  相似文献   

A Middle Ordovician crinoid from the beach gravels of Ristna Cape,Hiiumaa Island,Estonia     

Stephen K. Donovan  William I. Ausich  Mark A. Wilson  Mark E. Peter 《Proceedings of the Geologists' Association. Geologists' Association》2014

Reworked fossils may be exotic, but more typically are locally derived. Echinoderms have only rarely been identified from beach clasts; most commonly, these are Upper Cretaceous echinoids from the Chalk. A pebble collected from a beach in Estonia has yielded a moderately well preserved specimen of the crinoid stem, Baltocrinus (col.) antiquus (Eichwald). This species is typical of the Baltic region, only being known from the Middle Ordovician (Darriwilian) of Estonia, but is exotic because the local outcrop is Upper Ordovician to Silurian.  相似文献   

Incremental CH4 and N2O mitigation benefits consistent with the US Government's SC-CO2 estimates     

Alex L. Marten  Elizabeth A. Kopits  Charles W. Griffiths  Stephen C. Newbold  Ann Wolverton 《Climate Policy》2013,13(2):272-298

Benefit–cost analysis can serve as an informative input into the policy-making process, but only to the degree it characterizes the major impacts of the regulation under consideration. Recently, the US, amongst other nations, has begun to use estimates of the social cost of CO₂ (SC-CO₂) to develop analyses that more fully capture the climate change impacts of GHG abatement. The SC-CO₂ represents the aggregate willingness to pay to avoid the damages associated with an additional tonne of CO₂ emissions. In comparison, the social costs of non-CO₂ GHGs have received little attention from researchers and policy analysts, despite their non-negligible climate impact. This article addresses this issue by developing a set of social cost estimates for two highly prevalent non-CO₂ GHGs, methane and nitrous oxide. By extending existing integrated assessment models, it is possible to develop a set of social cost estimates for these gases that are consistent with the SC-CO₂ estimates currently in use by the US federal government.Policy relevanceWithin the benefit–cost analyses that inform the design of major regulations, all Federal agencies within the US Government (USG) use a set of agreed upon SC-CO₂ estimates to value the impact of CO₂ emissions changes. However, the value of changes in non-CO₂ GHG emissions has not been included in USG policy analysis to date. This article addresses that omission by developing a set of social cost estimates for two highly prevalent non-CO₂ GHGs, methane and nitrous oxide. These new estimates are designed to be compatible with the USG SC-CO₂ estimates currently in use and may therefore be directly applied to value emissions changes for these non-CO₂ gases within the benefit–cost analyses used to evaluate future policies.  相似文献   

Benchmark-based allocations in EU ETS Phase 3: an early assessment     

Oliver Sartor  Clement Pallière  Stephen Lecourt 《Climate Policy》2013,13(4):507-524

Phase 3 of the European Union Emissions Trading Scheme (EU ETS; 2013–2020) sees the introduction of new rules governing the free allocations of emissions allowances given to energy-intensive industries. In contrast to Phases 1 and 2, allocations will be based on historical production multiplied by best available emissions technology benchmarks. This article exploits an original database to provide a first analysis of the distributional and economic efficiency implications of the new rules. It is shown empirically that the new allocation rules reduce the scope for windfall gains by EU ETS firms while also effectively mitigating carbon leakage risks, even assuming optimistic forecasts of Phase 3 carbon prices. The example of the cement sector is used to show that benchmarking significantly improves the harmonization of the levels of free allocations to competing firms throughout the EU compared to Phase 2. However, it is also found that the use of ex ante output levels to determine allocations still leaves considerable scope for windfall gains and possible distortions of the internal market.  相似文献   

US public opinion on climate change issues: implications for consensus-building and policymaking     

Carolyn Kousky  Stephen H. Schneider 《Climate Policy》2013,13(4):359-372

While the Conference of the Parties wrangle at an international scale with climate policy, a quiet set of policies and measures is being implemented at a local scale by municipalities across the globe. This study examines the motivation municipalities have for undertaking policies to reduce their greenhouse gas emissions, when the theory of free-ridingwould predict that local administrations should find it difficult to unilaterally reduce their emissions for the benefit of the global climate. Through interviews with officials and/or staff in 23 municipalities in the United States enacting climate policy, data are gathered that suggest local government abatement policies are primarily a top—down decision based on what officials or staff members believe to be “good business” or rational policy choices. They are primarily driven by the potential for realised or perceived cost savings and co-benefits rather than by public pressure. Economic data from some dozen municipal projects are analyzed, finding, while municipalities lack sophisticated accounting techniques, some justification for the often-disputed claim that at least initial reductions in emissions can be made at cost savings. In the United States, with the lack of national abatement policies, it is municipalities that are leading the way in beginning to implement mitigation strategies, even if only for initial reductions.  相似文献   

What causes the spread of model projections of ocean dynamic sea-level change in response to greenhouse gas forcing?     

Couldrey  Matthew P.  Gregory  Jonathan M.  Boeira Dias  Fabio  Dobrohotoff  Peter  Domingues  Catia M.  Garuba  Oluwayemi  Griffies  Stephen M.  Haak  Helmuth  Hu  Aixue  Ishii  Masayoshi  Jungclaus  Johann  Köhl  Armin  Marsland  Simon J.  Ojha  Sayantani  Saenko  Oleg A.  Savita  Abhishek  Shao  Andrew  Stammer  Detlef  Suzuki  Tatsuo  Todd  Alexander  Zanna  Laure 《Climate Dynamics》2021,56(1-2):155-187

Sea levels of different atmosphere–ocean general circulation models (AOGCMs) respond to climate change forcing in different ways, representing a crucial uncertainty in climate change research. We isolate the role of the ocean dynamics in setting the spatial pattern of dynamic sea-level (ζ) change by forcing several AOGCMs with prescribed identical heat, momentum (wind) and freshwater flux perturbations. This method produces a ζ projection spread comparable in magnitude to the spread that results from greenhouse gas forcing, indicating that the differences in ocean model formulation are the cause, rather than diversity in surface flux change. The heat flux change drives most of the global pattern of ζ change, while the momentum and water flux changes cause locally confined features. North Atlantic heat uptake causes large temperature and salinity driven density changes, altering local ocean transport and ζ. The spread between AOGCMs here is caused largely by differences in their regional transport adjustment, which redistributes heat that was already in the ocean prior to perturbation. The geographic details of the ζ change in the North Atlantic are diverse across models, but the underlying dynamic change is similar. In contrast, the heat absorbed by the Southern Ocean does not strongly alter the vertically coherent circulation. The Arctic ζ change is dissimilar across models, owing to differences in passive heat uptake and circulation change. Only the Arctic is strongly affected by nonlinear interactions between the three air-sea flux changes, and these are model specific.

  相似文献   

Picnic in Siluria,by Paul Olver (producer). A Woolhope Club film,produced by field of vision, 2008. Running time: 26 min.     

Stephen K. Donovan 《Geological Journal》2011,46(6):651-651

  相似文献   

Groundwater-resource governance: Are governments and stakeholders responding to the challenge?     

Stephen Foster  Héctor Garduño 《Hydrogeology Journal》2013,21(2):317-320

  相似文献