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Stuttgart Mühlhausen, Germany

Klumpp R.,Bayerisches Landesamt fur Umwelt | Hartmann S.,KfW Bankengruppe | Wieprecht S.,Institute For Wasser Und Umweltsystemmodellierung

For retention of floods dry basins are in terms of ecological continuity particularly well suited, since the basin itself is not permanently submerged and the outlet structure is on an equal level as the natural riverbed. At the same time during retention events a free outflow as well as harmless energy dissipation at the outlet has to be ensured. Specific installations in an open culvert structure shall take account of these requirements. Source

Miyajima K.,University of Gottingen | Miyajima K.,Institute For Wasser Und Umweltsystemmodellierung | Noubactep C.,University of Gottingen | Noubactep C.,Kultur und Nachhaltige Entwicklung CDD e.V.
Chemical Engineering Journal

The impact of sand on the efficiency of metallic iron (Fe0) at discoloring a methylene blue (MB) solution in the presence of MnO2 was characterized. The MB initial concentration was 10 mg L-1. 22.0mL of this solution was used for each test. Investigated systems were: (i) Fe0 alone, (ii) MnO2 alone, (iii) sand alone, (iv) a sand/MnO2 mixture, and (v) Fe0/sand/MnO2 mixtures with three different natural MnO2-bearing minerals. Tested material loadings varied from 0.0 to 45.0gL-1. A commercial Fe0 and three natural MnO2 materials (Manganite, Psilomelane and X-MnO2) were tested in shaken experiments at 75rpm for 14days. The documented delay of MB discoloration by Fe0 in the presence of MnO2 was the evaluation criterion. This characteristic discoloration delay was observed for all tested materials at MnO2 loadings <6 g L-1. For higher MnO2 loadings, the Fe0/Manganite/sand system was more efficient than the Fe0/sand system. The largest extend of the delay of MB discoloration was observed in the Fe0/X-MnO2/sand system. This observation delineated the crucial importance of characterizing the intrinsic reactivity of tested MnO2 materials for comparable results. This study highlighted the crucial importance of experimental conditions as major source of confusing/conflicting reports. © 2014 Elsevier B.V. Source

Lange T.,University of Gottingen | Sauter M.,University of Gottingen | Heitfeld M.,Heitfeld Schetelig Consulting Geologists and Engineers GmbH | Schetelig K.,Heitfeld Schetelig Consulting Geologists and Engineers GmbH | And 6 more authors.
Environmental Earth Sciences

Hydraulic fracturing of unconventional gas reservoirs rapidly developed especially in the USA to an industrial scale during the last decade. Potential adverse effects such as the deterioration of the quality of exploitable groundwater resources, areal footprints, or even the climate impact were not assessed. Because hydraulic fracturing has already been practised for a long time also in conventional reservoirs, the expansion into the unconventional domain was considered to be just a minor but not a technological step, with potential environmental risks. Thus, safety and environmental protection regulations were not critically developed or refined. Consequently, virtually no baseline conditions were documented before on-site applications as proof of evidence for the net effect of environmental impacts. Not only growing concerns in the general public, but also in the administrations in Germany promoted the commissioning of several expert opinions, evaluating safety, potential risks, and footprints of the technology in focus. The first two publications of the workgroup "Risks in the Geological System" of the independent "Information and Dialogue process on hydraulic fracturing" (commissioned by ExxonMobil Production Deutschland GmbH) comprises the strategy and approaches to identify and assess the potential risks of groundwater contamination of the exploitable groundwater system in the context of hydraulic fracturing operations in the Münsterland cretaceous basin and the Lower Saxony Basin, Germany. While being specific with respect to local geology and the estimation of effective hydraulic parameters, generalized concepts for the contamination risk assessment were developed. The work focuses on barrier effectiveness of different units of the overburden with respect to the migration of fracking fluids and methane, and considers fault zones as potential fluid pathway structures. © 2013 Springer-Verlag Berlin Heidelberg. Source

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