Kubier, Andreas
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Item type:Publication, Cadmium in soils and groundwater: A reviewCadmium (Cd) is a non-essential trace element that is widely distributed in the environment. Both geogenic and anthropogenic sources can elevate Cd concentrations in soils and groundwater, which are important for maintaining healthy supplies of food and safe drinking water. Elevated Cd doses are carcinogenic to humans. The WHO Guidelines for Drinking-Water Quality recommend a guideline value for Cd of 3 μg/L. Important anthropogenic Cd sources include mining, atmospheric deposition of combustion emissions, and the use of Cd-containing fertilizers. We document several cases of Cd pollution in soil and groundwater based on worldwide accounts. Besides anthropogenic Cd sources, Cd is also incorporated into sulfides, carbonates, and phosphorites resulting in elevated Cd concentrations in associated rock types. The crustal median Cd content is 0.2 mg/kg. In soils, Cd occurs at concentrations of 0.01 to 1 mg/kg with a worldwide mean of 0.36 mg/kg. Weathering can lead to Cd concentrations up to 5 μg/L in soil water and up to 1 μg/L in groundwater. In aqueous solutions, Cd generally occurs as the divalent Cd2+ and it is mobilized mainly in oxic, acidic conditions. Cadmium sorption is enhanced by the presence of high amounts of hydrous oxides, clay minerals, and organic matter, and its mobility is further influenced by pH, the redox state, and ionic strength of the solution. However, Cd can remain in solution as water-soluble complexes with anions, such as CdCl+ and Cd(SO4)22-, and dissolved organic matter while sorption and precipitation decrease the aqueous concentration of most other heavy metals. As a consequence, Cd is one of the most mobile heavy metals in the environment. The elevated mobilization potential, e.g., through competition and ligand induced desorption, is the reason for faster Cd release from soil into groundwater than other heavy metals. The goal of this study was to present a broad overview of the origin and concentration of Cd in groundwater, and its reaction pathways in aquatic environments. To gain an overview of the hydrochemical behavior of Cd, cases of Cd pollution in soil and groundwater, studies investigating Cd release, and information about the legal framework were compiled.journal articleBand:108166 524 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Occurrence, reaction and transport behavior of cadmium in groundwater(2019-07-05); ; ; Cadmium (Cd) is a non-essential trace element that is widely distributed in the environment. It remains in solution at near neutral pH and is one of the most toxic elements in the environment. There is a lack of information about the processes that control Cd concentration in groundwater. Elevated Cd concentrations can be resultant from a multitude of natural and anthropogenic sources. The goal was to provide a better understanding about the source, transport, and fate of Cd in groundwater through the evaluation of a large hydrogeochemical data set. Above-threshold Cd concentrations were linked to specific groundwater compositions caused by land use in connection with acidification or nitrate. The main parameters affecting Cd mobility were pH and redox potential, which were linked to Cd sorption and release from minerals. Cadmium primarily occurred in shallow groundwater under oxic and autotrophic nitrate reducing conditions. Hydrogeological factors limited Cd retention capacity.doctoral thesis549 640 - 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:25240 143 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Cadmium in groundwater − A synopsis based on a large hydrogeochemical data setElevated cadmium (Cd) concentrations in groundwater have widespread implications for water supply and agriculture. The aqueous chemistry of Cd is considered not complex; however, aside from intense industrial pollution, multi-faceted hydrogeochemical interactions control Cd mobility. Therefore, the behavior of Cd in groundwater was investigated through statistical analyses of a large hydrogeochemical data set, which contained analyses from 6300 sampling locations in Northern Germany. Cadmium concentrations of above 0.5 μg/L were linked to groundwater conditions caused (1) by woodlands in connection with acidification or (2) elevated nitrate concentrations beneath farmland due to fertilization. Comparably, both geogenic and anthropogenic Cd input were less important. The main hydrogeochemical parameters affecting Cd mobility were pH and redox potential, which are probably linked to Cd sorption to mineral surfaces and Cd release from carbonates and sulfides, such as pyrite. Thus, Cd concentrations were primarily elevated when groundwater conditions were oxic and autotrophic nitrate reducing. In addition, enhanced groundwater recharge and limited Cd retention capacity by the aquifer matrix were responsible for elevated Cd concentrations in groundwater, potentially breaching legal regulations.journal articleBand:68989 107 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Verteilung stabiler Isotope im Grundwasser Nordwestdeutschlands: Untersuchung zum Einfluss von Kontinental‑, Höhen- und LandnutzungseffektDiese Arbeit liefert einen Überblick über die Verteilung der stabilen Isotope von Wasserstoff (δ2H) und Sauerstoff (δ18O) im Grundwasser Niedersachsens und Bremens anhand von 133 Grundwasserproben, die mit der Cavity-Ring-Down-Spectroscopy untersucht wurden. Die Ergebnisse zeigen das Auftreten eines Kontinentaleffekts in Nordwest-Südost-Richtung entlang der vorherrschenden Windrichtung mit einer Abreicherung des Isotopensignals im Wasser mit zunehmender Entfernung von der Küste (δ2H: −48,3 ‰; δ18O: −6,8 ‰) ins Landesinnere (δ2H: −56,8 ‰; δ18O: −7,8 ‰) sowie einen vermeintlichen Höheneffekt, der allerdings über eine große räumliche Entfernung auftritt und daher höchstwahrscheinlich nicht real ist, sondern durch den Kontinentaleffekt bestimmt wird. Des Weiteren wird die Abhängigkeit der δ2H- und δ18O-Werte des Grundwassers von der Evaporationsrate deutlich, die ihrerseits von der Bodenporosität und dem Pflanzenbewuchs abhängt und auf unterschiedliche Landnutzung oder das Vorkommen von verschiedenen hydrogeologischen Räumen zurückzuführen ist. Letztgenannte Effekte beeinflussen sich wechselseitig und sind ebenfalls durch den Kontinentaleffekt überprägt.journal articleBand:2496 55