Uwe Rauch

Urban Geochemistry: Investigations in the Berlin Metropolitan Area

The distribution of 41 trace and 11 major elements in 4000 samples of topsoils (0–20 cm) from the Berlin Megacity is interpreted. The detailed comparative analysis of the element distributions and the results of factor analysis showed that the distributions of the elements Al, K, Na, Rb, Zr, Nb and Ti are mainly natural origin, i.e. related to the composition of the parent material. Industrial and commercial areas often display considerably elevated values for Mo, Ni, As, Ag, Cr, Sb, Fe, Mn, Mg, P, TOC and especially Pb, Hg and electrical conductivity relative to the geogenic background of the area surrounding Berlin. Industrial areas tend to be characterised by contamination of the subsoil with Cu, Cd, Zn, Hg, Pb and Sn. In the area around Berlin, extensive, strong anamalies of Cd, Zn, Pb, Cu and Hg occur near iron and steel industries and construction materials industries, as well as in the vicinity of sewage farms.

Environmental aspects of the regional geochemical survey in the southern part of East Germany

Abstract From 1977 to 1985 an area of 14000 km2 of the new Federal States of Germany has been covered by a stream sediment and surface water geochemical survey. Approximately 18000 samples were collected and analysed for at least 31 trace and secondary elements. The chemistry of stream sediments is used to quantify natural geochemical baselines and anthropogenic effects. Surface water chemistry is less effective in establishing baselines because of additional factors such as modifications of the Eh-pH conditions with varied landscape type and rainfall amounts. Environmental geochemical aspects of the surface geochemistry were an integral part of the survey planning. One of the most important factors in the geochemical landscapes — land use — was also included in the statistical evaluation of geochemical data. The classification of geochemical anomalies is used to distinguish between inputs from natural element enrichments caused by mineralization, bed-rock sources, landscape type and anthropogenic effects. Multivariate statistical methods (principal component analysis, cluster-Q-analysis) determined multielement anomalies and their extent was mapped.

U-Th signatures of agricultural soil at the European continental scale (GEMAS): Distribution, weathering patterns and processes controlling their concentrations

Agricultural soil (Ap-horizon, 0-20cm) samples were collected in Europe (33 countries, 5.6millionkm2) as part of the GEMAS (GEochemical Mapping of Agricultural and grazing land Soil) soil-mapping project. The GEMAS survey area includes diverse groups of soil parent materials with varying geological history, a wide range of climate zones, and landscapes. The soil data have been used to provide a general view of U and Th mobility at the continental scale, using aqua regia and MMI® extractions. The U-Th distribution pattern is closely related to the compositional variation of the geological bedrock on which the soil is developed and human impact on the environment has not concealed these genuine geochemical features. Results from both extraction methods (aqua regia and MMI®) used in this study support this general picture. Ternary plots of several soil parameters have been used to evaluate chemical weathering trends. In the aqua regia extraction, some relative Th enrichment-U loss is related to the influence of alkaline and schist bedrocks, due to weathering processes. Whereas U enrichment-Th loss characterizes soils developed on alkaline and mafic bedrock end-members on one hand and calcareous rock, with a concomitant Sc depletion (used as proxy for mafic lithologies), on the other hand. This reflects weathering processes sensu latu, and their role in U retention in related soils. Contrary to that, the large U enrichment relative to Th in the MMI® extraction and the absence of end-member parent material influence explaining the enrichment indicates that lithology is not the cause of such enrichment. Comparison of U and Th to the soil geological parent material evidenced i) higher capability of U to be weathered in soils and higher resistance of Th to weathering processes and its enrichment in soils; and, ii) the MMI® extraction results show a greater affinity of U than Th for the bearing phases like clays and organic matter. The comparison of geological units with U anomalies in agricultural soil at the country scale (France) enables better understanding of U sources in the surficial environment and can be a useful tool in risk assessments.

GEMAS: CNS concentrations and C/N ratios in European agricultural soil

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 (Ap horizon) at 2108 sites with an even sampling density of one site per 2500km2 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.