Schadstoffbelastung, Reaktion der Oekosphaere und Wasserqualitaet. Teilvorhaben 1a und 1b Lage und Ausdehnung der Versauerungsfront in der Verwitterungsdecke von Diabas, Grauwacke/Tonschiefer und Quarzit an Beispielen aus der Soesemulde

SIGLEAvailable from TIB Hannover: F96B1665+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Depositionsbedingte Tiefengradienten der Bodenversauerung in der Soesemulde (Westharz)

Fuer das Einzugsgebiet der Soesemulde wird ein Szenario beschrieben werden, welches die Schadstoffbelastung, die Reaktion des Bodens/Sickerwasserleiters und der Bachwasserqualitaet beschreibt. Die saure Depositon fuehrt regelhaft zur Ausbildung einer Versauerungsfront in Boeden von Waldoekosystemen. Diese wandert unter fortgesetztem Saeure-Input weiter in die Tiefe. Die Reaktionsprodukte der Saeurepufferung an der Versauerungsfront sind hauptsaechlich Ca/MgSO_4-Salze. Diese verlassen mit dem Sickerwasserstrom das Oekosystem. Von dort aus gelangen sie direkt in den Bach und nicht in den tiefen Kluftgrundwasserleiter, da sie sich anschliessend im Seesediment wiederfinden lassen. Diesbezuegliche Untersuchungen zeigen, dass die Einzugsgebietsversauerung in der Soesmulde in den 50er Jahren dieses Jahrhunderts begonnen hat. Diese Entwicklung wird sich solange fortsetzen, bis der Sickerwasserleiter vollstaendig versauert ist. Die Aciditaet des Bachwassers entspricht dann der der Deposition. Mit Hilfe von Bachwassergenerierungsmodellen aus der Literatur wurde ein Modell erstellt, das die regionale Vorhersage des Eintritts von Gewaesserversauerung wesentlich vereinfacht und praezisiert. Des weiteren wurde ein auf das Geographische-Informations-System (GIS) gestuetzte Model entworfen, welches die Anfertigung regionaler Risikokarten ''Gewaesserversauerung'' ermoeglicht. (orig./BBR)For the catchment area fo the Soese basin, a scenario is presented which describes the pollutant load, the reaction of the soil/seepage water aquifer, and the creek water quality. Acid depositions regularly lead to the formation of an acidification front in soils of forest ecosystems which continues to migrate downward as the acid input continues. The reaction products of acid buffery at the acidification front are mainly Ca/MgSO_4 salts which leave the ecosystem with the seepage water current. From there, they are transported directly into the creek and not into the deep joint acquifer as they can be found in the lake sediment afterwards. Investigations show that acidification of the Soese basin started in the Fifties. This trend will continue until the seepage water aquifer is acidified completely. The acidity of the creek water will then equal the deposition. On the basis of creek water regeneration models from recent literature, a model was developed which makes regional forecasts on the onset of water acidification simpler and more precise. In addition a model based on the Geographical Information Model (GIS) was developed which permits the drawing-up of regional maps showing the water acidification risk. (orig./BBR)Available from TIB Hannover: RO 2404(98) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Measured and modelled retention of inorganic sulfur in soils and subsoils (Harz Mountains, Germany)

Atmospheric deposition has resulted in an accumulation of inorganic sulfur (S) in many forest soils. At Sosemulde (Hart Mountains) samples from 5-240 cm depth were analysed. Most sulfate (SO4) is accumulated at about 30-60 cm depth: 8.5-9.5 mmol(c) kg(-1). Large amounts can also be retained in < 100 cm. To assess changes in SO4 dynamics in time,adsorption isotherms have been included in several process-oriented models, e.g., in MAGIC. The Lange Bramke (LB) Model is the first model used on the catchment scale containing solubility products for the hydroxosulfate minerals jurbanite and alunite. By reconstructing the long-term acidification history (140 years) both models were successfully calibrated to a 14-year deposition, soil and streamwater data set at Lange Bramke catchment (Harz Mountains). According to MAGIC the present accumulation of SO4 in 0 - 80 cm is 8.7 mmol(c) kg(-1), while according to the LB-Model 10.2 mmol(c) kg(-1) are stored as jurbanite. Both models predicted 4.5 mmol(c) kg(c) SO4 in the subsoil layer, retained as alunite in the LB Model. These values correspond to the amounts measured in soil and subsoil samples at Sosemulde, respectively. However, for future scenarios with decreasing S inputs the models show different developments in SO4 concentrations. Changes in MAGIC are gradual whereas the LB model predicts stepwise decreasing SO4 values as soon as previously stored hydroxosulfates are fully dissolved. Such concentration "jumps" have not been observed