Zinc speciation in mining and smelter contaminated overbank sediments by EXAFS spectroscopy     

An Van Damme  Erik Smolders  Géraldine Sarret  Rudy Swennen 《Geochimica et cosmochimica acta》2010,74(13):3707-7820

Overbank sediments contaminated with metalliferous minerals are a source of toxic metals that pose risks to living organisms. The overbank sediments from the Geul river in Belgium contain 4000-69,000 mg/kg Zn as a result of mining and smelting activities, principally during the 19th century. Three main Zn species were identified by powder Zn K-edge EXAFS spectroscopy: smithsonite (ZnCO₃), tetrahedrally coordinated sorbed Zn (sorbed ^IVZn) and Zn-containing trioctahedral phyllosilicate. Smithsonite is a primary mineral, which accounts for approximately 20-60% of the Zn in sediments affected by mining and smelting of oxidized Zn ores (mostly carbonates and silicates). This species is almost absent in sediments affected by mining and smelting of both sulphidic (ZnS, PbS) and oxidized ores, presumably because of acidic dissolution associated with the oxidation of sulphides, as suggested by the lower pH of this second type of sediment (pH(CaCl₂) <7.0 vs. pH(CaCl₂) >7.0 for the first type). Thus, sulphide minerals in sediment deposits can act as a secondary source of dissolved metals by a chemical process analogous to acid mine drainage. The sorbed ^IVZn component ranges up to approximately 30%, with the highest proportion occurring at pH(CaCl₂) <7.0 as a result of the readsorption of dissolved Zn²⁺ on sediments constituents. Kerolite-like Zn-rich phyllosilicate is the major secondary species in all samples, and in some the only detected species, thus providing the first evidence for pervasive sequestration of Zn into this newly formed precipitate at the field scale.  相似文献   

Corrigendum to “Particle transport and distribution on the Mars Science Laboratory Mission: Effects of triboelectric charging” [Icarus 204 (2009) 545-557]     

Robert C. Anderson  Gregory H. Peters  Louise Jandura  Kenneth Manatt  Erik Pounders  Dan Sunshine 《Icarus》2010,207(2):1013

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Use of stream response functions to determine impacts of replacing surface-water use with groundwater withdrawals   总被引：1，自引：0，他引：1  

Erik B. Pruneda  Michael E. Barber  Diana M. Allen  Joan Q. Wu 《Hydrogeology Journal》2010,18(5):1077-1092

A regional-scale numerical groundwater model is used to study the impacts of replacing surface-water use with groundwater wells to improve low-flow stream conditions for endangered species within the Bertrand and Fishtrap watersheds, southern British Columbia, Canada and Washington, USA. Stream response functions ranging from 0 to 1.0 were calculated for individual wells placed within a steady-state groundwater flow model at varying distances from the streams to determine the impact that these replacement wells, operating under sustained pumping rates, would have on summer instream flows. Lower response ratios indicate groundwater pumping will have less of an impact on streamflow than taking an equivalent amount of water directly from a surface-water source. Results show that replacing surface-water use with groundwater withdrawals may be a viable alternative for increasing summer streamflows. Assuming combined response factors should be ≤0.5 for irrigators to undergo the expense of installing new wells, ~57% of the land area within 0.8 km of Bertrand Creek would be suitable for replacement wells. Similarly, 70% of the land area within 0.8 km of Fishtrap Creek was found to be appropriate. A visual analysis tool was developed using STELLA to allow stakeholders to quickly evaluate the impact associated with moving their water right.  相似文献   

Atlantic surface water inflow to the Nordic seas during the Pleistocene–Holocene transition (mid–late Younger Dryas and Pre‐Boreal periods, 12 450–10 000 a BP)     

Tine L. Rasmussen  Erik Thomsen  Tove Nielsen  Stefan Wastegård 《第四纪科学杂志》2011,26(7):723-733

The inflow of Atlantic Water to the Nordic seas from mid–late Younger Dryas to earliest Holocene (12 450–10 000 a BP) is reconstructed on the basis of a high‐resolution core (LINK14) from 346 m water depth on the east Faroe shelf. We have analysed the distribution of planktic and benthic foraminifera, stable isotopes and ice‐rafted debris (IRD), and calculated absolute temperatures and salinities by transfer functions. During the investigated time period there was almost continuous inflow of Atlantic Water to the Nordic seas. Deposition of IRD during the mid–late Younger Dryas and Pre‐Boreal coolings indicates the presence of melting icebergs and that summer sea surface temperatures were low. The east–west temperature gradient across the Faroe–Shetland Channel was much steeper than today. The cold conditions around the Faroe Islands are attributed to stronger East Greenland and East Icelandic currents than at present. The near‐continuous inflow of Atlantic Water is consistent with published evidence suggesting that deep convection took place in the Nordic seas, although the convection sites probably had shifted to a more easterly position than at present. Around the time of deposition of the Saksunarvatn Tephra c. 10 350 a BP, sea surface temperatures increased to the present level. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Surface deformation analysis of dense GPS networks based on intrinsic geometry: deterministic and stochastic aspects     

Khosro Moghtased-Azar  Erik W. Grafarend 《Journal of Geodesy》2009,83(5):431-454

In this contribution, the regularized Earth’s surface is considered as a graded 2D surface, namely a curved surface, embedded in a Euclidean space . Thus, the deformation of the surface could be completely specified by the change of the metric and curvature tensors, namely strain tensor and tensor of change of curvature (TCC). The curvature tensor, however, is responsible for the detection of vertical displacements on the surface. Dealing with eigenspace components, e.g., principal components and principal directions of 2D symmetric random tensors of second order is of central importance in this study. Namely, we introduce an eigenspace analysis or a principal component analysis of strain tensor and TCC. However, due to the intricate relations between elements of tensors on one side and eigenspace components on other side, we will convert these relations to simple equations, by simultaneous diagonalization. This will provide simple synthesis equations of eigenspace components (e.g., applicable in stochastic aspects). The last part of this research is devoted to stochastic aspects of deformation analysis. In the presence of errors in measuring a random displacement field (under the normal distribution assumption of displacement field), the stochastic behaviors of eigenspace components of strain tensor and TCC are discussed. It is applied by a numerical example with the crustal deformation field, through the Pacific Northwest Geodetic Array permanent solutions in period January 1999 to January 2004, in Cascadia Subduction Zone. Due to the earthquake which occurred on 28 February 2001 in Puget Sound (M _w > 6.8), we performed computations in two steps: the coseismic effect and the postseismic effect of this event. A comparison of patterns of eigenspace components of deformation tensors (corresponding the seismic events) reflects that: among the estimated eigenspace components, near the earthquake region, the eigenvalues have significant variations, but eigendirections have insignificant variations.  相似文献   

The Tertiary of Norden     

Erik S. Rasmussen Claus Heilmann-Clausen Regin Waagstein Tor Eidvin 《《幕》》2008,31(1):66-72

This chapter provides a lithostratigraphic correlation and the present knowledge of the depositional history of the Tertiary succession of the Scandinavian countries. The succession records an initial phase of carbonate deposition in the early Paleocene. This was succeeded by deposition of deep marine clays with intercalation of sand-rich mass-flow deposits during most of the Paleocene and Eocene. Volcanic activity in the North Atlantic was extensive at the transition from the Paleocene to the Eocene resulting in widespread sedimentation of ash-rich layers in the North Sea area. During the Oligocene, the first prograding deltaic complex developed, sourced from the Fennoscandian Shield. Late Oligocene-Early Miocene inversion and uplift of Norway and the Shetland Platform resulted in major progradation of coastal and delta plain systems. At the end of the Tertiary most of the North Sea basin was filled and the Fennoscandian Shield was flanked to the west by a broad, coalesced coastal plain.  相似文献   

Efforts to reduce sea turtle bycatch in the shrimp fishery in Northeastern Brazil through a co-management process     

Augusto César Coelho Dias da Silva  Jaqueline Comin de Castilhos  Erik Allan Pinheiro dos Santos  Luciana Sonnewend Brondízio  Leandro Bugoni 《Ocean & Coastal Management》2010,53(9):570-576

The neritic waters of the state of Sergipe in Northeastern Brazil is adjacent to the main nesting area of the olive ridley sea turtles (Lepidochelys olivacea) in the Western Atlantic Ocean and an important area for shrimp trawl fishery. To address the problem of incidental mortality of sea turtles captured during trawling and reduce the risk of overexploitation of shrimp stocks, Projeto TAMAR/ICMBio, a Brazilian sea turtle conservation program, has adopted two main strategies: (1) the implementation of a marine monitoring program and (2) active participation in local forums. This paper describes the conflicts among stakeholders, the arrangements and established mechanisms of negotiation aimed to protect sea turtles and shrimp grounds, and strategies to reduce conflicts between user groups. The analysis of this co-management process highlights the importance of stakeholder participation in resource management decision-making through a cooperative process, the role assumed by non-governmental organizations as mediators, and the factors that influence this system. The key factors and actions learnt from the current study include clear identification of the conflicts, identification of stakeholders – both local and external, and local leaders, encouragement of actors and leaders to participate, support and strengthening of local groups, legitimization of the discussion forums through involvement with government, formalization of decisions taken through legislation, and monitoring of the management efficacy.  相似文献   

Two Dimensional Wavelet Analysis Applied to Geoid Anomalies Mixing and High Rayleigh Number Mantle Convection     

Luke Vecsey  Cathy Hier  Dave Yuen  Erik Sevre 《Visual Geosciences》2001,6(3):1-6

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Thermal Convection in Finite Prandtl Number Fluids at High Rayleigh Number     

Catherine A. Hier  Stephen Y. Bergeron  David A. Yuen  Erik O. Sevre  John M. Boggs 《Visual Geosciences》2001,6(3):1-4

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Physiographically Controlled Allometry of Specific Sediment Yield in the Canadian Cordillera: A Lake Sediment-based Approach   总被引：2，自引：0，他引：2  

Erik Schiefer  Olav Slaymaker  & Brian Klinkenberg 《Geografiska Annaler: Series A, Physical Geography》2001,83(1-2):55-65

It is generally supposed that specific sediment yield declines as the drainage basin area increases, as part of the mobilized sediment becomes trapped in the downstream cascade of storage zones. In British Columbia, using fluvial suspended sediment load data, Church and Slaymaker (Nature 1989, Vol 337, pp. 452–454) have observed a pattern of increasing specific sediment yield at all spatial scales up to 3×10⁴km². This trend has been attributed to the dominance of secondary remobilization of Quaternary sediments over primary denudation of the land surface. Using a larger data set of lake sediment-based estimates of long-term sediment yield, sub-regional patterns of specific yield have been investigated for the Canadian Cordillera. Between spatial scales of 0.9 and 190 km² sediment yield trends are differentiated by physiography, as indicated by the variable allometry observed in the specific sediment yield–drainage basin area relations. Highest sediment yields were observed in the Coast Mountains where specific sediment yields conform to the regional pattern described by Church and Slaymaker. However, in flat-lying plateau and major valley areas specific sediment yield decreases with increasing drainage area, thus conforming to the conventional model of sediment delivery. In several other sub-regions of intermediate relief there were no significant relations between specific yield and drainage area. These results suggest that no single model of sediment yield is adequate to describe sediment transfer processes in the Canadian Cordillera at the sub-regional scale.  相似文献