Stratigraphic and geotechnical characterization of regionally extensive and highly competent shallow sand units in the southern North Sea

A detailed stratigraphic and geotechnical investigation of the uppermost 50 m below the sea floor was carried out for parts of the German North Sea sector using combined information from shallow seismic reflection surveys, 50-m-long sediment cores and cone penetration tests covering an area of ~150 km². While most recent studies concentrate on unusual features such as buried tunnel- or river-valleys, this study focused on the less well understood, regionally dominant sand units deposited after the retreat of the last glaciers in this region. We identified two sandy units which dominate the late- to post-Saalian geology: (i) the Upper Fluvial Member, believed to be derived from deposition of the Weser, Ems and Elbe palaeorivers as well as other tributaries of the Elbe Palaeovalley in the NE during the Saalian; and (ii) the Aeolian Member, which correlates with periglacial deposits of Weichselian age. Additionally, a Saalian Buried Valley Member believed to comprise fluvial deposit was also identified. Key stratigraphic units within the uppermost 50 m below the sea floor were also identified and mapped. Detailed geotechnical properties were obtained for each of the individual stratigraphic units. The regional extent of the Aeolian and Upper Fluvial Members was documented in the region west of the Elbe Palaeovalley and south of the Dogger Bank, where their geotechnical properties are important for foundation design. In conclusion, the study complements the established regional geotechno-stratigraphy and offers new and detailed publically accessible information beneficial for offshore wind farm development within the region.     

Interactive effects of hypoxia and polybrominated diphenyl ethers (PBDEs) on microbial community assembly in surface marine sediments

Hypoxia alters the oxidation–reduction balance and the biogeochemical processes in sediments, but little is known about its impacts on the microbial community that is responsible for such processes. In this study, we investigated the effects of hypoxia and the ubiquitously dispersed flame-retardant BDE47 on the bacterial communities in marine surface sediments during a 28-days microcosm experiment. Both hypoxia and BDE47 alone significantly altered the bacterial community and reduced the species and genetic diversity. UniFrac analysis revealed that BDE47 selected certain bacterial species and resulted in major community shifts, whereas hypoxia changed the relative abundances of taxa, suggesting slower but nonetheless significant community shifts. These two stressors targeted mostly different taxa, but they both favored Bacteroidetes and suppressed Gammaproteobacteria. Importantly, the impacts of BDE47 on bacterial communities were different under hypoxic and normoxic conditions, highlighting the need to consider risk assessments for BDE47 in a broader context of interaction with hypoxia.     

Alternative data reduction procedures for UVES: Wavelength calibration and spectrum addition

This paper addresses alternative procedures to the ESO supplied pipeline procedures for the reduction of UVES spectra of two quasar spectra to determine the value of the fundamental constant $\mu =M_p/M_e$ at early times in the universe. The procedures utilize intermediate product images and spectra produced by the pipeline with alternative wavelength calibration and spectrum addition methods. Spectroscopic studies that require extreme wavelength precision need customized wavelength calibration procedures beyond that usually supplied by the standard data reduction pipelines. An example of such studies is the measurement of the values of the fundamental constants at early times in the universe. This article describes a wavelength calibration procedure for the UV–visual Echelle spectrometer on the very large telescope, however, it can be extended to other spectrometers as well. The procedure described here provides relative wavelength precision of better than $3\times {10}^{-7}$ for the long-slit Thorium–Argon calibration lamp exposures. The gain in precision over the pipeline wavelength calibration is almost entirely due to a more exclusive selection of Th/Ar calibration lines.     

Controls on chemistry and diagenesis of naturally occurring iron-oxide phases

The purposes of this study were to (i) document chemical and mineralogical compositions in two naturally acidic drainages over a 1 m soil profile, (ii) document organic and inorganic signatures representative of past chemical or biological processes in the soils, and (iii) determine whether mineralogical and chemical differences are a consequence of differences in original composition, depositional conditions, or diagenesis. Two sites were studied: Paymaster Creek in the Heddleston Mining District near Lincoln, Montana and the New World Mining District near Cooke City, Montana. The oldest deposits at both naturally acidic sites pre-date human mining activity by several thousand years, although there is recent human activity at both sites. Both sites have streams with high dissolved Fe and moderately low pH and actively accumulate schwertmannite on streambeds. Soil deposits away from the streambed at Paymaster Creek contained goethite with adsorbed sulfate, but no schwertmannite, suggesting either that the original conditions precluded schwertmannite precipitation or that diagenesis occurred rapidly converting the schwertmannite to goethite. The New World Mining District site showed the expected profile, which is a gradual transition from schwertmannite- and goethite-bearing soils to goethite-only soils. Concentrations of Cr, As and other trace elements shown to retard diagenesis were higher at the New World site than at the Paymaster site.     

Long-term ecosystem and biogeochemical research in Loch Vale watershed,Rocky Mountain National Park,Colorado

Loch Vale watershed was instrumented in 1983 with initial support from the National Acid Precipitation Assessment Program to ask whether ecosystems of Rocky Mountain National Park (RMNP) were affected by acidic atmospheric deposition. Research and monitoring activities were expanded in 1991 by the U.S. Geological Survey Water, Energy, and Biogeochemical Budgets program to understand the processes, and their interactions, controlling water, energy, and biogeochemical fluxes. With help from many collaborators we have characterized trends and patterns in atmospheric deposition, climate, and hydrology, including glaciers and other ice features. Instead of acidic deposition, we documented high atmospheric inputs of reactive nitrogen (Nr), and have studied the ecological consequences in soils, surface water, and vegetation. Using paleolimnology, we documented the onset of human-caused change to lake primary producers ca. 1950 in response to increased Nr deposition and warming. Our results provided the basis for the Colorado Nitrogen Deposition Reduction Plan, a state policy that aims to reduce Nr emissions to protect resources in RMNP by 2032. Carbon cycle research revealed mountain wetlands now release more carbon than they store, and respiration and methane flux occurs even during winter through deep snow packs. Trend analyses found export of Nr to be closely tied to atmospheric inputs, but can lag in response to drought. Current research explores consequences of the combination of warming, changes in precipitation dynamics, and atmospheric deposition of Nr and dust on stream and lake CO₂ dynamics, lake biology and trophic state, and soil carbon composition. Dramatic increases in park visitors have prompted studies on the effects of recreational use on water quality. New tools such as remote sensing and high frequency instream water quality sensors are being applied to lake and stream studies. Monitoring, combined with experiments, models, and spatial comparisons is an essential foundation for science-based resource management.     

Persistence and Distribution of Temperate Intertidal Worm Reefs in Delaware Bay: A Comparison of Biological and Physical Factors

The sandbuilder worm Sabellaria vulgaris is widely found along the Mid-Atlantic region of the USA, but occurs in dense, reef-like structures in only one estuary. Reef formation and persistence was monitored in lower Delaware Bay along the western shoreline between 2001 and 2009 using ground surveys and aerial photography. These observations were combined with field larval settlement studies, laboratory low temperature susceptibility experiments, and an examination of the physical properties of the individual beaches to attempt to explain the location and persistence of the reefs. Neither exposure to temperature minima during spring low tides nor yearly variations in recruitment accounted for the observed reef distribution patterns. This study suggests that two physical factors, the distance from the beach to the 2-m isobath and the presence of coarse substratum >2 mm explain the greatest amount of variation in the observed distribution of intertidal S. vulgaris reefs and small aggregations.     

A magnetotelluric profile of the Wind River Thrust, Wyoming

Data from ten magnetotelluric (MT) stations over the Wind River Uplift and adjacent basins are interpreted with constraints from the Consortium for Continental Reflection Profiling (COCORP) seismic reflection data and from gravity data. The MT data reveal the general configuration of the conductive basins and resistive uplifts; low resistivity zones are interpreted as faults which correspond to those visible in the COCORP sections.

The Wind River Thrust Fault is modelled as a conductive zone that can be traced to a depth of at least 20 km, and the crust beneath the Green River Basin is about 40 km thick.

The modelled constant dip of the Wind River Thrust is consistent with a tectonic model of lateral compressive stress.     

Atmospheric Circulation Patterns Associated with Mortality Changes During the Transitional Seasons

Although much research has been done linking meteorological variables individually with various aspects of human health, few studies have considered the collective impact of weather. This study examines the relationship among ten synoptic-scale weather patterns and daily cause-specific human mortality rates for metropolitan areas in the central United States during the 1978 to 1998 autumn and spring seasons. The results show that distinctive changes in mortality rates are often associated with one or two of the more moderate synoptic types, displaying notable spatial and temporal variability. The occurrence of the Eastern Zonal (EZ) pattern during spring and the East Coast Trough (ECT) pattern during autumn seems to invoke the most significant increased mortality response across all causes of death and metropolitan statistical areas. For the EZ and ECT types, the largest adverse response occurs for locations influenced by cold, anticyclonic situations and atmospheric stability.     

Combining Surge and Wind Risk from Hurricanes Using a Copula Model: An Example from Galveston,Texas

Consideration of climate-related impacts on coasts is important to ensure readiness for disaster response. Local risk of storm surge and strong winds from hurricanes affecting Galveston, Texas, is quantified using a bivariate copula model fit to observed data. The model uses a two-dimensional Archimedean copula. Parametric uncertainty (5th and 95th percentiles) is quantified using a Monte Carlo procedure. The annual probability of a hurricane producing winds of at least 50 ms^?1 and a surge of at least 4 m is 1.7 percent with a 95 percent confidence interval of (1.33, 1.78) percent. The methodology can be extended to include inland flooding and can be applied elsewhere with available information.