First health and pollution study on harbor seals (Phoca vitulina) living in the German Elbe estuary

The Elbe is one of the major rivers releasing pollutants into the coastal areas of the German North Sea. Its estuary represents the habitat of a small population of harbor seals (Phoca vitulina). Only little is known about the health status and contamination levels of these seals. Therefore, a first-ever seal catch was organized next to the islands of Neuwerk and Scharhörn in the region of the Hamburg Wadden Sea National Park. The investigations included a broad set of health parameters and the analysis of metals and organic pollutants in blood samples. Compared to animals of other Wadden Sea areas, the seals showed higher γ-globulin levels, suggesting higher concentrations of pathogens in this near-urban area, elevated concentrations for several metals in particular for V, Sn, Pb, and Sr, and comparable ranges for chlorinated organic contaminants, except for elevated levels of hexachlorobenzene, which indicates characteristic inputs from the Elbe.     

A Stable and Efficient Numerical Algorithm for Unconfined Aquifer Analysis

The nonlinearity of equations governing flow in unconfined aquifers poses challenges for numerical models, particularly in field-scale applications. Existing methods are often unstable, do not converge, or require extremely fine grids and small time steps. Standard modeling procedures such as automated model calibration and Monte Carlo uncertainty analysis typically require thousands of model runs. Stable and efficient model performance is essential to these analyses. We propose a new method that offers improvements in stability and efficiency and is relatively tolerant of coarse grids. It applies a strategy similar to that in the MODFLOW code to the solution of Richard's equation with a grid-dependent pressure/saturation relationship. The method imposes a contrast between horizontal and vertical permeability in gridblocks containing the water table, does not require "dry" cells to convert to inactive cells, and allows recharge to flow through relatively dry cells to the water table. We establish the accuracy of the method by comparison to an analytical solution for radial flow to a well in an unconfined aquifer with delayed yield. Using a suite of test problems, we demonstrate the efficiencies gained in speed and accuracy over two-phase simulations, and improved stability when compared to MODFLOW. The advantages for applications to transient unconfined aquifer analysis are clearly demonstrated by our examples. We also demonstrate applicability to mixed vadose zone/saturated zone applications, including transport, and find that the method shows great promise for these types of problem as well.     

Seismic behaviour of timber-laced stone masonry buildings before and after interventions: shaking table tests on a two-storey masonry model

The present work focuses on the seismic behaviour of timber-laced masonry buildings with timber floors, before and after the application of intervention techniques. A two-storey building with timber ties (scale 1:2) was subjected to biaxial seismic actions. Prior to the execution of shaking table tests, the dynamic characteristics of the model were identified. The base acceleration was increased step-wise until the occurrence of significant but repairable damages. Afterwards, the masonry was strengthened by means of grouting, whereas the diaphragm action of the top floor of the building was enhanced and the model was re-tested. The tests on the timber reinforced model before strengthening show that the presence of timber ties within the masonry elements contributes to improved seismic behaviour. The performance of the model after strengthening shows that the selected intervention techniques led to a significant improvement of the seismic behaviour of the building model.     

Incorporating ‘catastrophic’ climate change into policy analysis

Although existing economic research is informative with regard to the importance of including potential ‘catastrophic’ climate change impacts in the analysis of GHG mitigation benefits, the generic and abstract form of the ‘catastrophe’ implemented has led to a lack of specific policy implications. This article provides an important starting point for a discussion of how to improve economic modelling of potential large-scale impacts of climate change. It considers how the term ‘abrupt climate change’ has been used in the scientific literature to describe changes in the climate system and carefully reviews the characteristics of the events that have been discussed in this context. The findings are compared to the way in which the economic literature has modelled potential economic and human welfare impacts of these ‘catastrophic’ events. In general, the economics literature is found to have modelled such impacts in a uniform way that fails to account for differences in relevant end points and timescales. The result is policy recommendations based on events that do not resemble those of concern. Better treatment of these events in integrated assessment modelling would help ensure that future research efforts can serve as meaningful policy input.     

The Nama Group revisited

The Nama Group of southern Namibia is a candidate for the Terminal Proterozoic Global Stratotype Section and Point (GSSP). Desirable characteristics of a GSSP include a well-preserved index-fossil assemblage, little deformation or metamorphism. well-constrained isotopic ages, stable-isotope records and magnetostratigraphic control. The age of the Nama Group sediments is now constrained to between 570 and 510 Ma. Assuming the Gondwana assembly was nearly complete at this same time, there is a discrepancy between the previously published Nama poles, a revised 550-510 Ma apparent polar wander path for Gondwana and the preceding supercontinental assemblages of Rodinia and Panottia. For these reasons, the Nama Group sediments were resampled in an effort to evaluate the potential of detailing the magnetostratigraphy of the Nama Group and resolving the discrepancy between the Nama poles and the APWP of Gondwana. Collectively, both the previous studies of the Nama Group and this one show a complex series of overprints and no easily discernible primary direction of magnetization. We therefore urge caution in using the Nama Group poles in any tectonic models of the Neoproterozoic-Early Palaeozoic. Specifically, the N1 component of magnetization, previously identified as a primary magnetization, was discovered in a younger suite of samples. Therefore, previous tectonic models that used the N1 magnetization direction as representative of the time of Nama deposition should be revised in light of these recent findings.     

The Oslo Rift: new palaeomagnetic and 40Ar/39Ar age constraints

⁴⁰Ar/³⁹Ar whole-rock and alkali feldspar ages demonstrate that dioritic to monzonitic dykes from Bøverbru and Lunner belong to the youngest recorded magmatic activity in the Oslo Rift region, southeast Norway. These dykes represent the terminal phase of rift and magmatic activity in the Oslo Graben, at the dawn of the Triassic (246–238 Ma).
  The Bøverbru and Lunner dyke ages are statistically concordant. However, the palaeomagnetic signature of the Bøverbru dyke is complex, and directions from the margins and the interior of the dyke differ in polarity. Therefore, the new Early Triassic palaeomagnetic pole for Baltica (Eurasia) is exclusively based on the less complex Lunner dykes and contacts (palaeomagnetic pole: latitude=52.9°N, longitude=164.4°E, dp / dm =4.5 ° /7.3°). The early Triassic palaeomagnetic pole [mean age: 243±5 Ma (2 σ )] is slightly different from the Upper Carboniferous–Permian (294–274 Ma) and Kiaman-aged poles from the Oslo Rift.