The GEMAS (geochemical mapping of agricultural soil) project collected 2108 Ap horizon soil samples from regularly ploughed fields in 33 European countries, covering 5.6 million km2. The <2 mm fraction of these samples was analysed for 53 elements by ICP-MS and ICP-AES, following a HNO3/HCl/H2O (modified aqua regia) digestion. Results are used here to establish the geochemical background variation and threshold values, derived statistically from the data set, in order to identify unusually high element concentrations for these elements in the Ap samples. Potentially toxic elements (PTEs),

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SUMMARY The average orientation and fabric anisotropy of interconnected pore spaces in sandstones is derived from magnetic pore fabric analysis, a new technique which measures the anisotropy of magnetic susceptibility (AMS) of samples impregnated with a magnetic suspension. In magnetic pore fabric analysis, the permeable part of the porous network, consisting of pore bodies connected by pore throats, is rendered magnetically susceptible. AMS directly yields the average elongation direction of pore bodies and offers a simple way to investigate the effect of pore‐shape anisotropy on petrophysical parameters such as hydraulic and electrical conductivity. AMS‐derived pore fabric of sandstones of moderate diagenetic state is compared to permeability anisotropy measured directly on the same specimens. For any one sample, the orientation of the two tensors and their representation ellipsoids correlate closely. The preferred orientation of interconnected pores facilitates fluid flow parallel to the direction of pore elongation and causes the observed anisotropy of permeability. Axial ratios of the two anisotropy ellipsoids correlate less closely but show a trend of proportionality. Compared to the time‐consuming measurement of directional permeabilities, magnetic pore fabric analysis may, therefore, provide a rapid way to estimate the orientation and, to a lesser extent, the degree of permeability anisotropy in porous sandstones. The analysis of six specimens extracted from a large, homogeneous block sample proves the accuracy and reliability of the method. In five fluvial sandstone samples, maximum permeability and pore elongation are roughly parallel to the palaeocurrent direction. Therefore, magnetic pore fabric analysis can also be used to study the relationship between permeability, pore fabric and sedimentary structures.

The pore fabric of sandstones is studied by impregnating porous samples with a magnetic suspension (ferrofluid) and subsequently measuring their anisotropy of magnetic susceptibility (AMS). Similar to the use of natural AMS for estimation of grain fabric, we determine average orientation and shape anisotropy of pore bodies in three dimensions. This new approach overcomes restrictions of previous methods of pore structure characterization. The interpretation of AMS in terms of pore fabric anisotropy is tested by comparison with pore shape observed in thin section. An image analytical technique is used to derive statistically the elongation direction of digitized pore cross sections. By computing the two-dimensional autocorrelation function we obtain section ellipses reflecting average pore shape and orientation. Combination of ellipses of three mutually perpendicular images leads to fabric ellipsoids comparable to AMS. Comparison of the two anisotropies shows a dose correspondence between the principal axis directions of AMS and fabric ellipsoids. Owing to the bedded nature of the samples, the ellipsoids are of oblate shape with minimum axes perpendicular to bedding. However, even small anisotropies within the bedding plane can be detected successfully. Axial ratios of AMS and fabric ellipsoids correlate dosely ff rock sample AMS is corrected for pore directional scattering. The method represents a powerful tool to analyze pore fabric of sedimentary rocks and to study its effects on petrophysical properties.

Variations of pore orientation, pore shape, porosity, and hydraulic permeability, within a siltstone unit of a fold‐thrust structure, are determined using magnetic pore fabric analysis, mercury injection porosimetry, and scanning electron microscopy (SEM). While samples in the foreland show evidence for the preservation of depositional pore geometry, the progressively deformed thrust sheet reveals increasingly oblate pore fabric anisotropy with microcrack planes oriented normal to the tectonic transport direction. Porosity, pore throat sizes, and permeability, show corresponding spatial variations across the structure. Independent of the deformation state within the thrust sheet, pore and magnetic grain fabric correlate closely in orientation.

A reliable overview of measured concentrations of TC, TN and TS, TOC/TN ratios, and their regional distribution patterns in agricultural soil at the continental scale and based on measured data has been missing - despite much previous work on local and the European scales. Detection and mapping of natural (ambient) background element concentrations and variability in Europe was the focus of this work. While total C and S data had been presented in the GEMAS atlas already, this work delivers more precise (lower limit of determination) and fully quantitative data, and for the first time high-quality TN data. Samples were collected from the uppermost 20cm of ploughed soil (A horizon) at 2108 sites with an even sampling density of one site per 2500km for one individual land-use class (agricultural) across Europe (33 countries). Laboratory-independent quality control from sampling to analysis guaranteed very good data reliability and accuracy. Total carbon concentrations ranged from 0.37 to 46.3wt% (median: 2.20wt%) and TOC from 0.40 to 46.0wt% (median: 1.80wt%). Total nitrogen ranged from 0.018 to 2.64wt% (median: 0.169wt%) and TS from 0.008 to 9.74wt% (median: 0.034wt%), all with large variations in most countries. The TOC/TN ratios ranged from 1.8 to 252 (median: 10.1), with the largest variation in Spain and the smallest in some eastern European countries. Distinct and repetitive patterns emerge at the European scale, reflecting mostly geogenic and longer-term climatic influence responsible for the spatial distribution of TC, TN and TS. Different processes become visible at the continental scale when examining TC, TN and TS concentrations in agricultural soil Europe-wide. This facilitates large-scale land-use management and allows specific areas (subregional to local) to be identified that may require more detailed research.

This study presents the current state of heavy metal contents in both urban and forest soils within the city area of Vienna, Austria. Based on a systematic survey of urban soils and on targeted sampling in forest areas, local and regional anomaly thresholds are derived using statistical methods and considering regional distribution patterns. For urban soils, local anomaly thresholds of elements Cu (60 mg/kg), Hg (0.5 mg/kg), Pb (100 mg/kg) and Zn (200 mg/kg) exceed national guideline values for uncontaminated urban soils and according to Austrian legislation fall into the category "anthropogenic contamination present but no damage to plants, animals or humans detectable". In forest soils within the city, thresholds are very similar to reference values for similar geological settings outside the city, apart from higher concentrations of elements Cr and Ni (threshold values of 107 and 64 mg/kg, respectively). Grouping urban soils according to land use reveals that Cd contents are 25 % higher, Pb contents 36 % higher, in traffic and industrial areas than in parks and like Cu, Hg and Zn, these elements can be shown to be at least partly caused by anthropogenic contamination. A dependency between heavy metal concentrations in soils and underlying geological units is shown within the flysch zone at the western city margin where the contents of elements Co, Cr, Cu, Ni and V are controlled by geology and reveal distinct differences between geological units. In built-up areas, no clear dependency between heavy metal contents in soils and geology is evident as urban soils represent accumulations by anthropogenic activity rather than in situ weathering products of underlying sediments.