Dust supply from river floodplains: the case of the lower Huang He (Yellow River) recorded in a loess–palaeosol sequence from the Mangshan Plateau

The Mangshan Plateau is located on the south bank of the Huang He (Yellow River) just west of the city of Zhengzhou, well outside the Loess Plateau in central China. Mixing models of the grain‐size data indicate that the loess deposits are mixtures of three loess components. Comparison of the mixing model with existing models established for a series of loess–palaeosol sequences from the Loess Plateau indicates that the Mangshan loess has been supplied from a proximal dust source, the Huang He floodplain, during major dust outbreaks. The high accumulation rates, the composition of the loess components, and especially the high proportions of a sandy loess component support this. Owing to the exceptionally high accumulation rates, the Mangshan grain size, magnetic susceptibility and carbonate records provide a high‐resolution archive of environmental and climate change. Copyright © 2008 John Wiley & Sons, Ltd.     

Study of a triple emission nebula in Orion

The Hii regions S254, 255 and 257 in the constellation of Orion are close together on the sky and appear like a triple object. Fabry-Pérot radial velocities of the Hii regions as well asUBV photo-electric magnitudes of their exciting stars are obtained. The data show that (1) all three nebulae are at a distance of 2.5 kpc; (2) an excess extinction is observed in S255 and S257 while S254 shows no excess extinction; (3) S255, identified as an IR and a molecular source, is the youngest object of the group. It is concluded that the three Hii regions are at different evolutionary stages.     

Passive Samplers for Monitoring VOCs in Groundwater and the Prospects Related to Mass Flux Measurements

Measurement and interpretation of mass fluxes in favor of concentrations is gaining more and more interest, especially within the framework of the characterization and management of large-scale volatile organic carbon (VOC) groundwater contamination (source zones and plumes). Traditional methods of estimating contaminant fluxes and discharges involve individual measurements/calculations of the Darcy water flux and the contaminant concentrations. However, taken into account the spatially and temporally varying hydrologic conditions in complex, heterogeneous aquifers, higher uncertainty arises from such indirect estimation of contaminant fluxes. Therefore, the potential use of passive sampling devices for the direct measurement of groundwater-related VOC mass fluxes is examined. A review of current passive samplers for the measurement of organic contaminants in water yielded the selection of 18 samplers that were screened for a number of criteria. These criteria are related to the possible application of the sampler for the measurement of VOC mass fluxes in groundwater. This screening study indicates that direct measurement of VOC mass fluxes in groundwater is possible with very few passive samplers. Currently, the passive flux meter (PFM) is the only passive sampler which has proven to effectively measure mass fluxes in near source groundwater. A passive sampler for mass flux measurement in plume zones with regard to long-term monitoring (several months to a year) still needs to be developed or optimized. A passive sampler for long-term monitoring of contaminant mass fluxes in groundwater would be of considerable value in the development of risk-based assessment and management of soil and groundwater pollutions.     

Walther Penck 1921: Pläne für eine deutsche Pazifik-Expedition

Sans résumé     

Hermann Wilhelm Abich im Kaukasus: Zum zweihundertsten Geburtstag

Hermann Abich was born in 1806 in Berlin and died in 1886 in Graz. He grew up in a wealthy family which had friendly relations with famous scientists like Alexander von Humboldt, Leopold von Buch or Carl Ritter. After his studies in Heidelberg and Berlin he turned to extended fieldwork at the volcanoes of Italy. In 1833–1834 he published excellent petrological/chemical results and got soon a good scientific reputation. Thus he was nominated as Professor for Geology and Mineralogy of the prestigious Russian University in Dorpat (now Tartu, Esthonia) in 1842. In 1844 he was sent to Armenia by the Russian authorities. For the next three decades his fieldwork with about 190 publications was concentrated on the Great and Lesser Caucasus. This was a period of Russian expansion to the South with long-lasting regional fights. But he enjoyed the support of powerful governors. He was an indefatigable and enthusiastic explorer and a precise observer and designer. His interests covered many fields: morphology, glaciology, structural geology, volcanology with Thermal Springs, mineral resources from hydrocarbons, coal, salt to ores, stratigraphy and paleontology as a base for geological maps. But he also gave advice for practical problems, and he was active in meteorology, botany and archaeology. Alltogether he became “the Father of Caucasus Geology”. The following sketch stresses only on three aspects of his activities. He was one of the first pioneers in hydrocarbon exploration, especially around the anticlines with the mud volcanoes near Baku. In many respects, however, his fundamental ideas were erronous. He explained the structure of the Great Caucasus by the traditional theories of Leopold von Buch and Elie de Beaumont. The Caucasus anticline “was elevated by forces acting from beneath”. Following them he tried to discover regularities in the strike of mountain chains. Similarily he treated volcanism like Alexander von Humboldt and Leopold von Buch with their two groups of phenomena: voluminous, mostly basaltic “elevation craters” versus isolated, mostly trachytic and relatively small cones of “true volcanoes”. In spite of the isolation of the Caucasus region he had cultivated continuously contacts with leading geologists in Europe and was honoured by many institutions. He left Russia in 1876 for Vienna planning to write there the final monograph volumes about his investigations but he died before he could complete them.     

Accumulation of Copper and Zinc in Danish Agricultural Soils in Intensive Pig Production Areas

Geografisk Tidsskrift, Danish Journal of Geography 105(2):15–22, 2005

The change of Cu and Zn concentrations in Danish agricultural soils was studied in areas with intensive pig production. Cu and Zn are found in pig manure as the metals are added to pig feed as growth promoters. The changes in concentrations of total and 0.02 MEDTA extractable Cu and Zn in soils from 1986 to 1998 were determined from samples taken at two depths (0–25 cm and 25–50 cm) from 73 sites. Pig manure and mineral fertilizer was added to 60 sites whereas fertilizer only was used on 13 sites. During the survey period soil Cu concentrations increased in both depths but mostly in the sites where pig manure was added. Furthermore, the results indicated that some plant-available Cu and Zn were transported from the topsoil to the subsoil. No significant change in soil Zn concentration was found although a slight reduction was observed. Comparing soil metal concentrations observed in 1998 to the total pig manure application in a 12-year period, it was observed that application of manure caused an accumulation of Cu and of Zn in the upper 50 cm soil. The accumulation rates correspond to the Cu and Zn concentrations in the pig manure.     

Limitations in the use of compound-specific stable isotope analysis to understand the behaviour of a complex BTEX groundwater contamination near Brussels (Belgium)

The application of compound-specific stable isotope analysis (CSIA) was evaluated to characterise a complex groundwater contamination. For this purpose, δ¹³C and δ²H analysis of benzenes and alkylated derivatives were used to interpret both the impact of different sources on a contaminant plume and the presence of degradation processes. The different contaminant sources could be distinguished based on their combined δ¹³C–δ²H signature of the benzene, toluene, ethylbenzene and xylenes (BTEX) dissolved in the groundwater. Despite this source differentiation, plume characterisation was not possible due to the complex mixing of the respective contaminant plumes. Furthermore, the original isotope signatures of the sources were not preserved across these plumes. To estimate the level of in situ biodegradation independently from concentration data, the Rayleigh equation was used. Although current literature identifies the application of CSIA as very promising in the frame of characterising organic groundwater pollution, this study has indicated that this approach can be limited with respect to successfully distinguish the different plumes and their relation to the known source zones.     

Containment of groundwater pollution (methyl tertiary butyl ether and benzene) to protect a drinking-water production site in Belgium

The subsurface migration of methyl tertiary butyl ether (MTBE) and benzene towards a drinking-water production site in Belgium was monitored for 9 years. A large gasoline spill at a nearby fuel station had caused a 500-m long and 50-m-wide pollution plume of MTBE (10?30 mg/L) and benzene (2?10 mg/L). In order to prevent any intrusion of pollutants into the drinking-water supply, a conceptual model was used to design a pump-and-treat system that intercepted the gasoline-contaminated groundwater emanating from the spill. The contaminated soil in the spill zone was excavated. A numerical mass transport model was developed to evaluate the ongoing plume containment. The model describes the subsurface MTBE migration and was regularly updated, based on groundwater monitoring data and the measured mass of MTBE extracted with the pump-and-treat system. With continued interception pumping, the MTBE plume can be remediated in 14 years. Without it, MTBE and benzene concentrations up to 600 μg/L could have reached the drinking-water production site and the plume would persist for 9 years longer. Source zone treatment combined with plume interception pumping is a suitable risk-based remediation strategy for the containment of MTBE and benzene groundwater pollution.     

Erratische Blöcke—erratische Folgerungen: ein unbekannter Brief von Leopold von Buch von 1818

At the beginning of the 19th century it was still not understood how erratic blocs were transported. Leopold von Buch's answer echoed Horace Bénedict de Saussure's flood theory from 1780. Von Buch's letter of 1818, published here, shows that he tried to support Saussure's theory to which he adhered to throughout his life with quantitative arguments. Even close contacts and several visits to Jean de Charpentier, the then director of the salt mines at Bex, who could demonstrate that the Rhône Glacier had once reached the Swiss Jura, and field trips with Louis Agassiz in the Neuchâtel area in 1837, failed to change von Buch's flood theory. His authority was one of the reasons why the Skandinavian iceshield was not generally thought to have extended into Northern Germany until 1875, when Otto Martin Torell located surfaces polished by ice near Berlin—an observation that provoked a sudden surge of affirmative publications. Erratic blocks were not the only topic on which von Buch was mistaken, but because of his many important contributions in other areas, including his shift from neptunism to plutonism or his observations concerning the uplift of Scandinavia, Alexander von Humboldt characterized him as "the greatest geognosist of our time".