Koopmann, Sarah
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Item type:Publication, Occurrence and mobility of molybdenum during managed aquifer recharge in carbonate aquifers(2023-02-03); ; ; Molybdenum (Mo) is an essential trace element for human health, although a high intake can be detrimental to humans. The risk of an increased Mo intake from drinking water is generally low. Still, interactions of groundwater with sediments enriched in naturally occurring (geogenic) Mo can result in Mo concentrations that exceed recommendations for drinking water. Such interactions are triggered primarily by anthropogenic disturbances of the naturally prevailing physicochemical conditions in the aquifer. An intensive release of Mo in carbonate aquifers is particularly problematic as large proportions of the world's population depend on carbonate aquifers as a drinking water resource. For example, the population of Florida derives most of its drinking water from the Floridan Aquifer System (FAS), the principal karstic carbonate aquifer in Florida and one of the most productive aquifers in the world. However, the cyclic injection, storage and recovery of oxygenated water in the anoxic FAS during the operation of Aquifer Storage and Recovery (ASR), which is the most commonly applied technique of managed aquifer recharge (MAR), caused the release of Mo in groundwater at several locations in Florida. Exceptionally high concentrations were observed during the operation of ASR in the Eocene Avon Park Formation (APF) as part of the FAS, with concentrations of Mo exceeding the recommendations for drinking water several times. Since ASR operations are important for drinking water supplies in Florida and many other parts of the world, this study investigated the occurrence and main source of Mo in the carbonate aquifer matrix and the processes that affect the mobility of Mo in groundwater to improve the risk assessment of Mo release during MAR. The findings are based on laboratory-scale geochemical analyses and reactive transport modeling on carbonate aquifers covering the APF but are also transferable to similar carbonate aquifers worldwide.doctoral thesis359 253 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Eisen-Mangan-Anomalien im Grundwasser: Analyse der beeinflussenden ProzesseIm oberflächennahen Grundwasser Norddeutschlands wurden höhere Mangan- als Eisenkonzentrationen beobachtet. Diese Beobachtung wurde als Anomalie angesehen, da die Konzentration des Eisens (Fe) typischerweise mindestens 10-mal höher ist als die des Mangans (Mn). Um das Auftreten dieser Anomalien besser zu verstehen, wurden zwei Grundwassermessstellen mit unterschiedlichen Fe/Mn-Verhältnissen untersucht. Das Redoxpotenzial und der pH-Wert wurden als singuläre Steuerung der Anomalie ausgeschlossen, da beide Grundwässer außerhalb des Stabilitätsfeldes für Fe2+ im Eh-pH Diagramm lagen. Darüber hinaus war Mangankarbonat im anomalen Grundwasser stabil. Ein vierwöchiger Batchversuch mit Torfmaterial zeigte einen Anstieg der Konzentrationen von Mn und Fe. Derselbe Versuch mit Zugabe von Nitrat zeigte jedoch nur eine Erhöhung der Mangankonzentration, was darauf hindeutet, dass die Oxidation von Fe2+ durch Nitrat die Ursache für die unterschiedlichen Fe/Mn-Verhältnisse an den beiden Standorten ist. Daher sollte der Nitrateintrag in oberflächennahe Grundwasserleiter einen entscheidenden Einfluss auf die Fe/Mn-Verhältnisse im Grundwasser haben.journal articleBand:25238 143