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61.
Sizable areas in northwestern arctic Russia have undergone fundamental change in recent decades as the exploration of vast hydrocarbon deposits has intensified. We undertook two case studies on the influence of oil and gas activities within neighbouring federal districts in the tundra zone. Employing a strongly interdisciplinary approach, we studied the ecological, spatial and social dimensions of the visible and perceived changes in land use and land cover. Our data are derived from field sampling, remote sensing and intensive participant observation with indigenous Nenets reindeer herders and non-indigenous workers. Important trends include the rapid expansion of infrastructure, a large influx of workers who compete for freshwater fish, and extensive transformation from shrub- to grass- and sedge-dominated tundra. The latter represents an alternative ecosystem state that is likely to persist indefinitely. On terrain disturbed by off-road vehicle traffic, reindeer pastures’ vegetation regenerates with fewer species among which grasses and sedges dominate, thus reducing biodiversity. To have maximum forage value such pastures must be accessible and free of trash, petro-chemicals and feral dogs. We found that a wide range of direct and indirect impacts, both ecological and social, accumulate in space and time such that the combined influence is effectively regional rather than local, depending in part on the placement of facilities. While incoming workers commonly commit poaching, they also serve as exchange partners, making barter for goods possible in remote locations. In general, the same positive and negative impacts of the presence of industry were mentioned in each study region. Even using very high-resolution remote sensing data (Quickbird-2) it is not possible to determine fully the amount of degraded territory in modern oil and gas fields. With regard to policy, both biophysical and social impacts could be substantially reduced if information flow between herders and workers were to be optimized.  相似文献   
62.
Abstract

Economic studies suggest that market leakage rates of greenhouse gas abatement can reach the two-digit percentage range. Although the Marrakesh Accords require Clean Development Mechanism (CDM) projects to account for leakage, most projects neglect market leakage. Insufficient leakage accounting is facilitated by a lack of applicable methods regarding the quantification and attribution of project-related leakage effects. This article proposes a method for attributing CDM-related market leakage effects to individual projects. To this purpose, alternative attribution methods are analysed. We find that project-specific approaches fail to take account of market leakage effects. Consequently, we propose to estimate aggregate market leakage effects and attribute them proportionally to individual projects. We suggest that predetermined commodity-specific leakage factors are applied by project developers to any emission reductions that are associated with a project's leakage-relevant demand or supply changes. This approach is conservative, equitable, incentive-compatible and applicable at manageable costs.  相似文献   
63.
A method for determining the distribution of supermicrometer nitrate between size-segregated sea-salt and soil derived particles is presented. The analysis is based on field data from six measurements at a coastal site in southern Finland, and on a theoretical treatment taking into account the transfer of gaseous species onto particle surfaces and their subsequent reaction. Significant amounts of nitrate were found in both the particle types, with the fraction of nitrate associated with soil particles varying from 20–50% in the 1–2 m size to near 90% in particles larger than 10 m. Overall, the nitrate accumulation followed closely the relative abundances of these two particle types. Two overlapping modes in supermicron nitrate mass size distributions could be identified. The lower mode, associated with sea-salt, was located between the surface-area and volume distribution of sodium peaking at about 2–3 m of EAD. The upper mode peaked at 3–5 m and followed more closely the surface-area distribution of calcium in all samples. At our site, the accumulation of nitrate into both particle types was shown to be limited by an effective surface reaction rate rather than by gas-phase diffusion. This rate was estimated to be considerably larger for sea-salt particles. Strong evidence in support of the saturation of nitrate in sea-salt particles were obtained.  相似文献   
64.
65.
The western Peloponnese was repeatedly hit by major tsunami impacts during historical times as reported by historical accounts and recorded in earthquake and tsunami catalogues. Geological signatures of past tsunami impacts have also been found in many coastal geological archives. During the past years, abundant geomorphological and sedimentary evidence of repeated Holocene tsunami landfall was found between Cape Katakolo and the city of Kyparissia. Moreover, neotectonic studies revealed strong crust uplift along regional faults with amounts of uplift between 13 m and 30 m since the mid-Holocene. This study focuses on the potential of direct push in situ sensing techniques to detect tsunami sediments along the Gulf of Kyparissia. Direct push measurements were conducted on the landward shores of the Kaiafa Lagoon and the former Mouria Lagoon from which sedimentary and microfaunal evidence for tsunami landfall are already known. Direct push methods helped to decipher in situ high-resolution stratigraphic records of allochthonous sand sheets that are used to document different kinds of sedimentological and geomorphological characteristics of high-energy inundation, such as abrupt increases in grain size, integration of muddy rip-up clasts and fining upward sequences which are representative of different tsunami inundation pulses. These investigations were completed by sediment coring as a base for local calibration of geophysical direct push parameters. Surface-based electrical resistivity tomography and seismic data with highly resolved vertical direct push datasets and sediment core data were all coupled in order to improve the quality of the geophysical models. Details of this methodological approach, new in palaeotsunami research, are presented and discussed, especially with respect to the question of how the obtained results may help to facilitate tracing tsunami signatures in the sedimentary record and deciphering geomorphological characteristics of past tsunami inundation. Using direct push techniques and based on sedimentary data, sedimentary signatures of two young tsunami impacts that hit the Kaiafa Lagoon were detected. Radiocarbon age control allowed the identification of these tsunami layers as candidates for the ad 551 and ad 1303 earthquake and tsunami events. For these events, there is reliable historical data on major damage on infrastructure in western Greece and on the Peloponnese. At the former Mouria Lagoon, corroborating tsunami traces were found; however, in this case it is difficult to decide whether these signatures were caused by the ad 551 or the ad 1303 event.  相似文献   
66.
This paper presents a damage–viscoplastic cap model for rocks with brittle and ductile behavior under low‐velocity impact loading, which occurs, e.g. in percussive drilling. The model is based on a combination of the recent viscoplastic consistency model by Wang and the isotropic damage concept. This approach does not suffer from ill posedness—caused by strain softening—of the underlying boundary/initial‐value problem since viscoplasticity provides a regularization under dynamic loading by introducing an internal length scale. The model uses the Drucker–Prager (DP) yield function with the modified Rankine criterion as a tension cut‐off and a parabolic cap surface as a compression cut‐off. The parabolic cap is smoothly fitted to the DP cone. The strain softening law in compression is calibrated with the degradation index concept of Fang and Harrison. Thereby, the model is able to capture the brittle‐to‐ductile transition and hardening behavior of geomaterials under highly confined compression, which is the prevailing stress state under a bit‐button in percussive drilling. Rock strength heterogeneity is characterized statistically at the structural level using the Weibull distribution. An explicit time integrator is chosen for solving the FE‐discretized equations of motion. The contact constraints due to the impact of an indenter are imposed with the forward increment Lagrange multiplier method that is compatible with explicit time integrators. The model is tested at the material point level with various uniaxial and triaxial tests. At the structural level confined compression, uniaxial tension tests and a rock sample under low‐velocity impact are simulated. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
67.
“Honest broker” refers to scientists facilitating complex political decisions from a neutral position, aiming to expand the scope of choice available instead of advocating a certain policy. This article reflects on the experiences of three scientists acting as honest brokers while carrying out a multicriteria evaluation to help politicians choose the water supply option for the city of Oulu, Finland. The process was considered successful and many politicians said that they have never before been that well informed when making a decision. The case primarily shows that besides the common knowledge brokerage roles targeting knowledge exchange, the honest brokerage approach relates more to managing social relationships and balancing political games and rapidly evolving discussions. Trustful relationships increased the perceived credibility of the brokers and ensured two-way communication. On the other hand, the brokers faced ethical dilemmas and difficulties of staying impartial while finding out confidential information related to political strategies.  相似文献   
68.
69.
A high-resolution geochemical profile from a 5,500-year-old sediment core of Lake Lehmilampi in eastern Finland was analyzed to study long-term trends and variability in element concentrations and accumulation rates. The accumulation rates of all studied elements followed the same trend, responding to changes in the total sedimentation rate. Concentration profiles differed among elements and showed considerable variation over time. Principal components analysis (PCA) was used on the concentration data to identify groups of elements that have similar geochemical controls. The first principal component was influenced by changes in mineral matter accumulation, and it incorporated elements that are associated with stable allochthonous minerals (such as Mg, K, Cs, Rb, Li, Ti and Ga), as well as elements in forms that become diluted when mineral matter increases (e.g., S, Fe and Mn). The second and third principal components showed that a large proportion of the variance was accounted for by elements with continuously increasing or decreasing concentrations related to pedogenetical development of the catchment soil. In the case of Hg, Pb and Cd, however, accumulation rates increased faster at the surface than is simply accounted for by changes in total sedimentation rates. For Cu, Cr, Ni and Zn, concentrations increased over the past 150 years, but there were no indications of a significant addition due to atmospheric deposition. These elements had more variable concentrations before the mid nineteenth century than after, as did elements that are often used for normalization. These findings suggest that lake sediments may not properly reflect the history of atmospheric metal deposition in remote areas.  相似文献   
70.
The large-scale CELEBRATION 2000 seismic experiment investigated the velocity structure of the crust and upper mantle between western portion of the East European Craton (EEC) and the eastern Alps. This area comprises: the Trans-European Suture Zone, the Carpathian Mountains, the Pannonian Basin and the Bohemian Massif. This experiment included 147 chemical shots recorded by 1230 seismic stations during two deployments. Good quality data along 16 main and a few additional profiles were recorded. One of them, profile CEL03, was located in southeastern Poland and was laid out as a prolongation of the TTZ profile performed in 1993. This paper focuses on the joint interpretation of seismic data along the NW–SE trending TTZ–CEL03 transect, located in the central portion of the Trans-European Suture Zone. First arrivals and later phases of waves reflected/refracted in the crust and upper mantle were interpreted using two-dimensional tomographic inversion and ray-tracing techniques. This modelling established a 2-D (quasi 3-D) P-wave velocity lithospheric model. Four crustal units were identified along the transect. From northwest to southeast, thickness of the crust varies from 35 km in the Pomeranian Unit (NW) to 40 km in the Kuiavian Unit, to 50 km in the Radom–Łysogóry Unit and again to 43 km in the Narol Unit (SE). The first two units are thought to be proximal terranes detached from the EEC farther to the southeast and re-accreted to the edge of the EEC during the Early Palaeozoic. The origin of the remaining two units is a matter of dispute: they are either portions of the EEC or other proximal terranes. In the area of the Polish Basin (first two units), the P-wave velocity is very low (Vp < 6.1 km/s) down to depths of 15–20 km indicating that a very thick sedimentary and possibly volcanic rock sequence, whose lower portion may be metamorphosed, is present. The velocity beneath the Moho was found to be rather high, being 8.25 km/s in the northwestern portion of the transect, 8.4 km/s in the central sector, and 8.1 km/s in the southeastern sector.  相似文献   
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