Surface cracks—geomorphological indicators for late Quaternary halotectonic movements in Northern Germany

Loading and unloading effects of the Scandinavian Ice Sheet triggered halotectonic movements in Northern Germany. We present newly detected geomorphological features—termed surface cracks—which indicate a relation between ice sheet-induced salt movement and surface processes. As a part of the Central European Basin System, numerous Zechstein salt structures are abundant in the North German Basin. On the basis of high-resolution digital terrain data, more than 160 surface cracks were mapped in Northern Germany, which were grouped into 30 clusters. Almost all of the surface cracks occur above the top regions of Zechstein salt structures. The surface cracks can be several kilometres long, up to more than 20 m deep and more than 100 m wide. The comparison of the shape of the salt structures and the orientation of the cracks reveals a geometric dependency, indicating that the cracks preferably occur near the crest margins of the salt structures. Furthermore, 3D seismic data from two sites show that subsurface faults originating from salt movement exist beneath the surface cracks. We interpret the cracks as surface ruptures due to ice sheet-induced halotectonic movements. The cracks occur in a variety of Quaternary sediments and landforms. This indicates that widespread halokinetic movements occurred in the region after the last (Weichselian) deglaciation and likely before the thawing of the permafrost, possibly in a time frame from c. 30–20 ka until c. 15 ka.     

The Importance of Microbial Iron Sulfide Oxidation for Nitrate Depletion in Anoxic Danish Sediments

Nitrate (NO₃ ^?) reduction processes are important for depleting the NO₃ ^? load from agricultural source areas before the discharge water reaches surface waters or groundwater aquifers. In this study, we experimentally demonstrate the co-occurrence of microbial iron sulfide oxidation by NO₃ ^? (MISON) and other NO₃ ^?-depleting processes in a range of contrasting sediment types: sandy groundwater aquifer, non-managed minerotrophic freshwater peat and two brackish muddy sediments. Approximately 1/3 of the net NO₃ ^? reduction was caused by MISON in three of the four environments despite the presence of organic carbon in the sediment. An apparent salinity limitation to MISON was observed in the most brackish environment. Addition of high surface area synthetically precipitated iron sulfide (FeS _x ) to the aquifer sediment with the lowest natural FeS _x reactivity increased both the relative fraction of NO₃ ^? reduction linked to MISON from approximately 30–100 % and the absolute rates by a factor of 17, showing that the potential for MISON-related NO₃ ^? reduction is environmentally significant and rate limited by the availability of reactive FeS _x .     

Towards Better WMS Maps Through the Use of the Styled Layer Descriptor and Cartographic Conflict Resolution for Linear Features

Abstract

Mercator depicted Croatia on several general maps. In accordance with the level of geographical knowledge, map scales and technical possibilities of the time, Mercator provided a relatively detailed depiction of basic geographical features on these maps. His interest in mapping Croatia was probably motivated by the fact that the Venetian Republic, the Habsburg Monarchy and the Ottoman Empire had fought over this area in the sixteenth century, contributing to the fragmentation of the medieval Croatian State, while at the same time facilitating economic, religious, linguistic, artistic and scientific communication between Central, South East and Mediterranean Europe. Mercator paid special attention to toponyms that enabled geographical objects to be identified and the decoding of cartographic contents. Research into Mercator’s maps has shown that geographical names, among other things, clearly indicate the sources of spatial data that he used. Additionally, geographical names on Mercator’s maps are significant indicators of the linguistic and cultural contacts that were particularly prominent in border areas, for example, along the eastern Adriatic coast, or the courses of the Danube, Sava and Drava.     

Groundwater contamination risks from conservative point source pollutants in a future climate

ABSTRACT

The groundwater contamination risk in future climates was investigated at three locations in Sweden. Solute transport penetration depths were simulated using the HYDRUS-1D model using historical data and an ensemble of climate projections including two global climate models (GCMs), three emission scenarios and one regional climate model. Most projections indicated increasing precipitation and evapotranspiration until mid-century with a further increase at end-century. Results showed both increasing and decreasing groundwater contamination risks depending on emission scenario and GCM. Generally, the groundwater contamination risk is likely to be unchanged until mid-century, but higher at the end of the century. Soil and site specific relationships between Δ(P – PET) (i.e. change in the difference between precipitation, P, and potential evapotranspiration, PET) and changes in solute transport depths were determined. Using this, changes in solute transport depths for other climate projections can be assessed.     

Meteorological Observations in 2000 at the Arctic Station,Qeqertarsuaq (69°15'N), Central West Greenland

An automatic meteorological station has been operating at the Arctic Station (69°15'N, 53°31'W) in West Greenland since 1990. This paper summarizes meteorological parameters during 2000 including snow and sea ice cover, ground temperatures and active layer development, and presents comments on the local permafrost thickness.     

Meteorological Observations in 1995 at the Arctic Station,Qeqertarsuaq (Godhavn), Central West Greenland/Concentrational Agriculture: Types,Functions, and Derivation/Den Danske Nationalkomité for Geografi

In October 1990 an automatic meteorological station was established at the Arctic Station (69°15'N, 53°31'W), Qeqertarsuaq (Godhavn), Central West Greenland, The station register parameters each 20 min, and the parameters have been described in an earlier paper in this journal by Nielsen et al. (1995). The present paper summarises main points of the climate during 1995.

Concentrational agriculture, defined as types of agriculture based on local concentration of plant nutrients, encompasses two main types: shifting cultivation and infield-outfield systems. They may ecologically be characterised by their mode of concentration: either by a vertical or a horisontal transfer (‘pumping’) of nutrients, respectively. The use of the general term ‘concentrational agriculture’ for the two forms is advocated by demonstrating that functional substitution of one by the other is possible, and by showing that the one type theoretically can be derived from the other. Historically, infield-outfield systems are supposed to be developed from some form of shifting cultivation.

Kort beretning om virksomheden i 1995

Justering af medlemskredsen. I forbindelse med valg af repræsentanter fandt en justering af repræsentationsområder sled (Århus Universilet har ikke længere fagområdet ‘kulturgeografi’). Videnskabernes Selskab har i samme forbindelse bifaldet, at fire observatører, repræsenterende undervisningstrinene i geografi deltager i møderne.     

Elemental and isotopic carbon and nitrogen records of organic matter accumulation in a Holocene permafrost peat sequence in the East European Russian Arctic

A peat deposit from the East European Russian Arctic, spanning nearly 10 000 years, was investigated to study soil organic matter degradation using analyses of bulk elemental and stable isotopic compositions and plant macrofossil remains. The peat accumulated initially in a wet fen that was transformed into a peat plateau bog following aggradation of permafrost in the late Holocene (～2500 cal a BP). Total organic carbon and total nitrogen (N) concentrations are higher in the fen peat than in the moss‐dominated bog peat layers. Layers in the sequence that have lower concentrations of total hydrogen (H) are associated with degraded vascular plant residues. C/N and H/C atomic ratios indicate better preservation of organic matter in peat material dominated by bryophytes as opposed to vascular plants. The presence of permafrost in the peat plateau stage and water‐saturated conditions at the bottom of the fen stage appear to lead to better preservation of organic plant material. δ¹⁵N values suggest N isotopic fractionation was driven primarily by microbial decomposition whereas differences in δ¹³C values appear to reflect mainly changes in plant assemblages. Positive shifts in both δ¹⁵N and δ¹³C values coincide with a local change to drier conditions as a result of the onset of permafrost and frost heave of the peat surface. This pattern suggests that permafrost aggradation not only resulted in changes in vegetation but also aerated the underlying fen peat, which enhanced microbial denitrification, causing the observed ¹⁵N‐enrichment. Copyright © 2012 John Wiley & Sons, Ltd.     

Arctic Ocean manganese contents and sediment colour cycles

Cyclical variations in colour and manganese content in sediments from the central Arctic Ocean have been interpreted to represent climatically controlled changes in the input of Mn from the Siberian hinterland, and/or variations in the intermediate and deep water ventilation of the Arctic basins, although a diagenetic origin has not been excluded. A reinvestigation of core 96/12-1pc using an Itrax X-ray fluoresence (XRF) core scanner confirms that these colour cycles are indeed controlled by variations in Mn content, although changes in the source region of the sediment may override the Mn colour signal in certain intervals. The prominent Mn cycles show no correspondence to any of the other measured elements. This decoupling of Mn and the bulk chemistry of the sediment is taken to indicate that the cycles observed are caused by variations in water column ventilation and riverine input, rather than variations in sediment source or diagenesis. We therefore conclude that the Mn maxima do represent warm phases with increased ventilation and/or riverine input, and that they therefore could be used for chronostratigraphic correlation between cores from the central Arctic Ocean, where traditional isotope stratigraphy is difficult or impossible to establish because of the lack of calcareous microfossils.