RESUMEN
Commissioned by Germany's Working Group of the Federal States on Water Problems (LAWA) the authors developed a procedure to define natural groundwater conditions from groundwater monitoring data. The distribution pattern of a specific groundwater parameter observed by a number of groundwater monitoring stations within a petrographically comparable groundwater typology is reproduced by two statistical distribution functions, representing the "natural" and "influenced" component. The range of natural groundwater concentrations is characterized by confidence intervals of the distribution function of the natural component. The applicability of the approach was established for 17 hydrochemical different groundwater typologies occurring throughout Germany. Based on groundwater monitoring data from ca. 26,000 groundwater-monitoring stations, 40 different hydrochemical parameters were evaluated for each groundwater typology. For all investigated parameters the range of natural groundwater concentrations has been identified. According to the requirements of the EC Water Framework Directive (article 17) (WFD) this study is a basis for the German position to propose criteria for assessing a reference state for a "good groundwater chemical status".
Asunto(s)
Agua Dulce/análisis , Contaminación del Agua/análisis , Conservación de los Recursos Naturales/legislación & jurisprudencia , Conservación de los Recursos Naturales/métodos , Monitoreo del Ambiente/legislación & jurisprudencia , Monitoreo del Ambiente/métodos , Geografía , Alemania , Modelos Teóricos , Movimientos del Agua , Contaminantes Químicos del Agua/análisis , Contaminación del Agua/prevención & controlRESUMEN
Commissioned by Germany's Working Group of the Federal States on Water Problems (LAWA) the authors developed a procedure to define natural groundwater conditions from groundwater monitoring data. The distribution pattern of a specific groundwater parameter observed by a number of groundwater monitoring stations within a petrographically comparable groundwater typology is reproduced by two statistical distribution functions, representing the "natural" and "influenced" components. The range of natural groundwater concentrations is characterized by confidence intervals of the distribution function of the natural component. The applicability of the approach was established for four hydrochemically different groundwater typologies occurring throughout Germany. Based on groundwater monitoring data from 7920 groundwater monitoring stations, 15 different hydrochemical parameters were evaluated for each groundwater typology. For all investigated parameters the range of natural groundwater concentrations has been identified. According to the requirements of the EC Water Framework Directive (article 17) (WFD) this study is a basis for the German position to propose criteria for assessing a reference state for a "good groundwater chemical status".
Asunto(s)
Geología , Abastecimiento de Agua/análisis , Monitoreo del Ambiente , Fenómenos Geológicos , Alemania , Hierro/análisis , Nitratos/análisis , Potasio/análisisRESUMEN
Retinal macroaneurysms are often misdiagnosed. Although the vast majority of cases are symptom-free or lead to perianeurysmal exudates and bleeding, a few rare cases show rupture and bleeding into the vitreous body. In four patients who had been referred because of acute visual deterioration caused by a vitreous hemorrhage of unknown origin, the peripheral fundus could initially be examined ophthalmoscopally. Six weeks later, bleeding recurred in one eye, making examination impossible. Ultrasound examinations showed that the central retinae of all four eyes were not detached. In one case, a small, solid elevation close to the macula was observed at B-scan. Following spontaneous resorption of the vitreous hemorrhages, fluorescein angiography showed one macroaneurysm in each of two eyes and two macroaneurysms in the other two eyes, located in each case in the temporal arteries. Following laser treatment in 3 of the 4 cases, no further hemorrhages were observed in any of the patients over a follow-up period of 4 to 15 months.