Untersuchungen zum Benzininhaltstoff Methyltertiär-butylether (MTBE) in Grund- und Oberflächenwasser in Deutschland

German Federal authorities do not see an acute environmental risk of the use of MTBE in gasoline. Within this study, however, MTBE concentrations of > 20 μg/l (the taste and odour threshold) in groundwater downstream of gasoline spills were found at five out of ten investigated sites. The measured MTBE concentrations at these sites ranged between 29 and 87,800 μg/l. Apparently, subsurface contamination with MTBE has also remained undetected at other sites in Germany. The ether is virtually unretarded in the aquifer and only degrades slowly, if at all. Spills of MTBE-amended gasoline can therefore cause extensive groundwater contamination. The occurrence of MTBE in groundwater will typically cause a significant increase of investigation and remediation costs. The measured MTBE concentrations in surface water samples from this study ranged between 18 and 199 ng/l (detection limit: 10 ng/l). In order to gain an overview about the actual extent of MTBE-contamination in Germany, MTBE should be included into the regular monitoring programs at gasoline spill sites.     

Reaktionsfronten bei der Infiltration von Oberflächenwasser ins Grundwasser

A sediment core for investigating porewater and solid constituents was taken from a reservoir at the river Ruhr (Schwerte, Germany). Balances of calculated porewater fluxes lead to a new evaluation of the role of the organic rich sediment for the maintainance of redox reactions that are observed during the infiltration into the underlying aquifer. The results prove that it is possible to balance the electron demand with the particulate organic matter that is trapped in the limnic sediment. As a consequence the formerly predicted downstream movement of redox fronts in the infiltrated aquifer will not be observed if sedimentation and water chemistry won't change dramatically. The determined trace element contents of porewater and sediments show the improved water quality of the river Ruhr throughout the last decades. Especially concentration profiles of the trace elements copper, arsenic and molybdenum give evidence of a flood catastrophy in 1943, caused by the destroyal of the reservoir Möhnetalsperre, located some kilometers upstream.     

Messung der Infiltrationsgeschwindigkeit von Oberflächenwasser mit Hilfe des natürlichen Isotops Radon-222

Owing to its different concentrations in groundwater and river water, the naturally occuring isotope radon-222 can be used as a natural tacer to determine the residence time of freshly infiltrated water and the infiltration velocity. In the study area, predominant correlation was found between the radon activity concentration of groundwater and the lithologic structure of the aquifer. Misinterpretation of low radon activity concentration measured near surface waters due to geological inhomogeneities can result in false assumptions about groundwater flow paths. The infiltration of river water into the adjacent aquifer during a flood wave was also ascertained by measuring radon activity concentration. Further the residence time of infiltrated water was determined at a sampling point installed beneath the river Elbe and infiltration velocity was calculated.     

Auftreten von Pflanzenschutzmitteln in Oberflächengewässern und im Grundwasser

An overview of the current situation of pesticide occurrence in water is presented using data from the EU-contries Denmark, England, France, Germany, and the Netherlands. Data were extracted from official reports. The data base is rather heterogenous, as the monitoring strategies vary in a wide range depending on the administrative responsibilities. In the publications, water pollution with pesticides is evaluated using the drinking water standard values for single substances (0,1 μg/l), a toxicological evaluation is missing. In surface waters, substances with regionally high sell numbers or high application amounts dominate. They belong to the chemical groups triacines, phenoxy carbolic acids and urea derivates. Talking about groundwater, the time scale has to be considered as well, as the geological system reacts as a buffer. Here, the triacines and their metabolits dominate having been applicated for tens of years in high amounts. Different measures to obtain a longterm water protection are discussed.     

Wechselwirkungen zwischen Grundwasser und Oberflächenwasser an einem Tieflandfluss (Spree)

Water exchange processes in the floodplain of a lowland groundwater-surface water system are studied on the basis of a study site near Freienbrink, NE Germany. The boundaries of this site are formed by an oxbow and the current bed of the river Spree, section Müggelspree. Surface and ground water levels were collected in 12 piezometers and at two recording stage gauges of a 300?m long transect throughout a one-year-period. Due to water level fluctuations, alternating periods of infiltration and exfiltration have been observed. However, most of the time groundwater flux is directed into the river Spree and river water infiltration events into the aquifer are usually short and of minor importance. Due to clogging of the oxbow bed, the hydraulic contact between the oxbow and the adjacent aquifer is marginal. These features are modelled quantitatively using MODFLOW in order to simulate ground water flow in the local aquifer.     

Pflanzenbehandlungs- und Schädlingsbekämpfungsmittel in Grund- und Quellwässern eines verkarsteten Kluftaquifers

The study presented deals with the occurence of pesticides and herbicides in space and time within a confined groundwater reservoir of 13 km ² extension. This fractured aquifer Schöppinger Berg in the northwestern part of the Münsterland (Germany) consists of calcareous sandstones and calcareous marlstones of Campanian (upper cretaceous) age and can be described as a natural lysimeter. 3,5 Mill. m ³ water per year run off on an aquitard in overflow springs alone a margin at the basis of the Schöppinger Berg into the local receiving streams. During the one-year-period of investigation 54% of the spring water samples were contaminated exceeding the allowed EU standard of 100 ng/l per chemical substance; 26% of the samples were polluted in excess of the 500 ng/l standard for all detected herbicides. There is a significant analogy between the occurence of pesticides and the concentration of nitrates in springs and wells. The occurence of these chemicals depends mostly on the rate of the water flow from the springs. During the high flow observed in the winter period, an increase in the pesticide and nitrates contents in groundwater and spring water was documented. Apart from run off- and interflow-effects, the application of herbicides during autumn is already measurable in the water samples of the following winter period in spite of a more than 50 m distance from the groundwater level.     

Bedeutung und Verhalten von Arsen in der Hydrosphäre

The redox speciation of the inorganic arsenic species As(III) and As(V) has deep influence on the element's toxicity and mobility. In groundwater sorption and redox processes occur with respect to the solid phase and the soluble arsenic species. Thereby manganese oxides and iron hydroxides play an important role. Manganese(IV) oxides are known as effective oxidants of As(III), iron(III) hydroxides surface bind both species by surface complexation. The task of this article is to give a short overview concerning the global cycling and behavior of arsenic and then focus on the redox behavior in the aquatic system influenced by manganese oxides and iron hydroxides. Results of previous investigations are shown and expanded by new findings of own studies. Studies were carried out under controlled geochemical conditions using batch systems with arsenic and MnO ₂ and FeOOH, respectively. The sorption and redox processes were investigated using extraction methods combined with solid phase surface analyses by XANES. The results indicate a slow oxidation process of As(III) at the iron hydroxide surface.     

Schadstoffmassenströme zwischen Grundwasser, Flussbettsedimenten und Oberflächenwasser am regional kontaminierten Standort Bitterfeld

As a result of intensive industrial, mining, and urban development, numerous large-scale contaminated areas exist in Germany. These so-called megasites represent a challenge to risk assessment and remediation strategies. At the Bitterfeld megasite, the contaminated groundwater interacts with the local streams. Along a stream reach 280?m long, the mass flow rates of chlorinated benzenes were estimated by combining integral pumping tests, streambed temperature mapping, and analyses of contaminant concentrations in the streambed sediments. On average, a total mass flow rate of 617?mg d^–1 monochlorobenzene (MCB) and 157?mg d^–1 dichlorobenzene (DCB) is released from the adjoining aquifer into the stream along the investigated reach. Further, the streambed sediment acts as the dominant contaminant source. Considering the streambed sediments, the contaminant mass flow rate to the river increases to values between 2,355 and 4,323 mg d^–1 MCB and between 892 and 3,587 mg d^–1 DCB.     

Geophysikalische Verfahren zur Erkundung und Charakterisierung von Grundwasserleitern in quartären Rinnen

Geophysical methods for the investigation and characterization of groundwater resources in porous media are shown using the subglacial Ellerbeker Rinne as an example. Five seismic sections illustrate the shape, internal structure and surrounding hydrostratigraphy of 25?km of this buried valley that, in some places, is more than 2?km wide. Data from the transient electromagnetic airborne survey reveal the distribution of electrical resistivity down to a depth of 300?m. The groundwater-saturated channel in the valley is clearly distinguishable from the Tertiary clays. A good and fast overview on the character of the confining beds down to 100?m depth was provided by the frequency-domain helicopter-borne electromagnetic method. A reliable interpretation was obtained by combining the different methods with borehole information and expert geological knowledge.     

Grundwasser- und Oberflächenwasserumsatz in Trinkwasservorkommen der Östlichen Bodenwöhrer Senke,Oberpfalz

Grundwasser - Die Östliche Bodenwöhrer Senke in der Oberpfalz, Bayern, bietet aufgrund ihrer besonderen geologischen Situation ergiebige Grundwasservorkommen in Keuper- und...     

Untersuchung ausgew?hlter Oberfl?chen-, Grund- und?Bodenwasserproben auf Perchlorat in Deutschland: Erste?Ergebnisse

Perchlorate is a component found in solid rocket fuels, explosives, fireworks, and road flares. In addition, perchlorate is a minor component of natural salt deposits in semiarid and arid regions. Discharge and storage areas as well as accidents are potential sources for perchlorate contamination of aquatic systems. Perchlorate has been detected in surface water and groundwater from several places worldwide. The aim of this study is to evaluate whether perchlorate occurs in surface water, groundwater, or soil leachate at selected sites in Germany. These sites include surface water from a military base in southern Germany, groundwater from a production site, and groundwater and soil leachate from a location where fireworks shows are performed regularly. Results show that perchlorate was detected in all surface water and groundwater samples with values around 1???g/l. Highest values (up to 15,000???g/l) were detected in pore waters of the ??Maifeld?? area in Berlin where soil was sampled immediately after a fireworks show.     

Markierungsversuche und Modellierung zur Bewertung der Gefährdung eines Trinkwasserbrunnens

A tracer experiment with uranine in a gravel aquifer aimed to assess the risk of a drinking water well near Pratteln, Switzerland, resulting from a contaminated site 760?m further upgradient. The experiment revealed a maximum linear flow velocity of 127?m/d and a mass recovery of 0.93?%. The tracer was also detected at two intermediate monitoring wells. This paper discusses the causes of this high flow velocity. Three different analytical models allowed simulation of the breakthrough curves and determination of transport parameters. A two-dimensional numerical model (FEFLOW) with simplified geometry provided a hydrogeologically consistent and probable explanation of all results. The aquifer is most likely relatively homogeneous, the steep hydraulic gradient (6?‰) and high conductivity (3?·?10^–2?m/s) cause high flow velocities, and most of the tracer passed northeast of the wells. Recently conducted small scale pumping tests largely confirmed this conceptual model. These findings should be considered for future protection measures.     

Untersuchungen zur Sorptionsreversibilität von organischen Schadstoffen in Aktivkohle, Holzkohle und Zeolith Y-200

Numerous studies have shown that sorption of organic contaminants in soils is dominated by the natural organic carbon content (C _org) of the soil. However, it is still under discussion whether sorption processes are fully reversible or whether an irreversibly sorbed contaminant fraction remains in the soil. This is especially important when considering soil remediation measures and its targets. In multi-stage sorption-desorption batch experiments with TCE, PCE, ortho-xylene and para-xylene and with the sorbents activated carbon, charcoal and a hydrophobic zeolite Y-200, the reversibility of sorption was studied. It could be shown that the structural features of the sorbents are of ample importance for the occurrence of a desorption-resistant fraction. While sorption was mainly reversible for the micro-porous zeolite Y-200 with a rigid pore network, charcoal and the activated carbon showed significant desorption hysteresis. However, following a subsequent sorption step, this fraction eventually desorbs and is re-mobilized.     

Regionalisierungsverfahren zur Ausweisung von Hydrotopen in von periglazialem Hangschutt geprägten Gebieten

Hydrologically homogenous regions were determined within a GIS environment using generally available data sets. In particular, a regionalization approach was developed that delineates spatially the structure and the lithology of periglacial drift covers. This approach is based on the genesis of the hill slope and its covering material. It is of great importance, as the source area of hill slopes is very important for lateral runoff components. The results show a plausible spatial delineation for the Brugga basin, 40 km ² , Black Forest Mountains. The suitability of the approach was shown for the surrounding Dreisam basin (258 km ² ) using a soil map (BÜK 200). The results are the basis for an improved process-oriented rainfall/runoff modelling, and for a holistic environment and landscape management.     

Ein Gesamtkonzept zur Ermittlung der seismischen Vulnerabilität von Bauwerken – am Beispiel unterirdischer Ver- und Entsorgungsleitungen

An overall concept for calculating the seismic vulnerability of buildings – at the example of underground pipelines. Earthquakes present a great risk for the safety of human lives and man-made buildings. While the extend of an earthquake that has to be expected at a specific location is well known through seismological mapping the resulting damage of buildings is more difficult to determine. Even more difficult is the prediction of the expected financial consequences, however, this is the most important question for the insurance industry. For this reason this article presents an overall concept for calculating the damage extend of buildings and the resulting financial loss on three different levels of accuracy. The developed overall concept is presented considering as example underground pipelines. However, especially the developed damage indicators and the methods for calculating the financial loss are transferable to other building types in an analogous manner. This flexibility is among others guaranteed by the modular design of the program system and the web based user surface.     

Beitrag zur Berechnung der Durchbiegung von Stahlbetonbauteilen und Kritik an der ÖNORM B 4700

A contribution to the calculation of the deflection of reinforced concrete members. Stated below you will find a calculation of the deflection of reinforced concrete. It differs from former calculations of the deflection according to the Austrian standard ÖNORM B4700 – reinforced concrete structures (EUROCODE-based calculation, dimensioning and constructive design) – and Austrian standard ÖNORM B4200/8 in that it takes into consideration, among others, the results of tests and represents the processes realistically. The load-bearing structures in Austria which were calculated according to the above-mentioned Austrian standards and feature a precamber still have a camber after decades. This may be regarded, among others, as an indication for an incorrect calculation of the deflection. It is therefore requested that the calculation method for the deflection of reinforced concrete specified in ÖNORM B4700 – reinforced concrete structures – firstly, be removed from this standard because it is not correct, as will be shown; secondly, restrict itself to stating the slendernesses, as is the case with DIN 1045, and to calculate the deflection according to the considerations contained in this paper, for example; and thirdly, to leave the calculation method to the structural engineers, which would also put an end to their anguish. Since the standards also represent the state of the art and have to be observed, this additionally poses a legal problem. As will be shown, the method for calculating the deflection according to ÖNORM B4700 contains serious errors of thought and wrong presuppositions in its basic approach, already.     

Charakterisierung von Karstgrundwasserleitern durch Simulation der Aquifergenese und des Wärmetransports

This paper is intended to provide an overview of an integrated modelling approach which allows for long-term simulations of aquifer genesis and for short-term simulations of heat transfer in karst aquifers as well. This approach is based upon a conceptual model of karst systems incorporating their dualistic flow pattern, calcite dissolutions kinetics and heat transport processes. The modelling tool which has been developed proves to be a useful device for testing hypotheses on the structure of karst aquifers and for investigating typical scenarios of the development of carbonate aquifers. For this purpose, two examples referring to a dendritical conduit network which is coupled to a fissured system are discussed.     

Ermittlung der hydraulischen Durchlässigkeit von quartären Sedimenten mittels Siebanalysen und Pumpversuchen

Fluvial sediments in the Babenhausen area (southeast of Frankfurt am Main) form an important reservoir of sand and gravel, which is currently being mined in dredged lakes. As the fluvial sediments also contain a productive aquifer which is intensely used, possible contamination of the groundwater by sand and gravel mining must be prevented. In order to estimate risk potential, the spatial distribution of hydraulic conductivity in these sediments must be determined. On a test site (50?×?40 m) directly within the riparian zone of a dredged lake, standard pumping tests, multilevel pumping tests, sieve and sedimentation analyses were carried out. Investigations enabled locating zones with high hydraulic conductivities at specific depths. The hydraulic conductivities determined from each of these methods show a similar trend with increasing depth, but often differ by one order of magnitude.