Cadmium Background Levels in Groundwater in an Area Dominated by Agriculture

Abstract

Cadmium is a highly toxic trace metal, which can be of geogenic or anthropogenic origin, for example, minerals, phosphate fertilizers, and combustion emissions. Due to its low sorption affinity compared to other heavy metals, Cd is easily mobilized, potentially resulting in elevated Cd concentrations in groundwater. This study assessed background levels of Cd in groundwater related to hydrogeology and hydrogeochemical processes through evaluation of a large hydrogeochemical data set composed of groundwater analyses from 6300 wells in Northwestern Germany. Calculated Cd background levels in groundwater were between 0.01 µg/L in hydrogeological units with mainly reducing conditions and 0.98 µg/L in less reducing groundwater recharge areas. The results showed that groundwater Cd concentrations above 0.5 µg/L (the German threshold value) are not necessarily elevated but could be the regional or ambient background level, depending on the hydrogeological unit. What would be considered as ambient background levels, however, indicated the influence by continuous intensive land use as well as the local geology, which is dominated by glacial deposits. Cadmium concentrations in groundwater were mainly controlled by hydrogeochemical and hydrogeological parameters and not by the amount of anthropogenic Cd input, in particular through the use of phosphate fertilizers. Instead, analyses of the solid phase revealed that Cd release from the aquifer matrix due to changes in hydrogeochemical parameters was more likely. Aquifer sediments in Northwestern Germany can be enriched in Cd originating from multiple sources, which in turn can cause elevated Cd concentrations in groundwater. Integr Environ Assess Manag 2019;00:1–11. © 2019 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC)

Cadmium im Grundwasser Nordwestdeutschlands – Herkunft, Mobilisierung und Bewertung nach EU-Wasserrahmenrichtlinie

“…Die Geesten unterscheiden sich dabei im Vergleich zu den Niederungen insbesondere durch ihr Relief und ihre geologische Entstehung. Hydrogeologische Merkmale gegenüber den Niederungen sind größere Flurabstände, eine hohe Grundwasserneubildung und ein teils geringes Schutzpotenzial der Deckschichten für das Grundwasser (Ad-hoc-Arbeitsgruppe Hydrogeologie 2016; Elbracht et al 2016 (Kubier und Pichler 2019;Kubier et al 2020), sodass es teilweise zu inhaltlichen Überschneidungen kommt. Diese sind jedoch für ein besseres Verständnis des Zusammenhangs zwischen Wasserrahmenrichtlinie und entsprechenden Maßnahmen der zuständigen Behörden erforderlich.…”

“…Ein Bis auf wenige kleine Teilräume konnten flächendeckend Hintergrundwerte für Cd abgeleitet werden (Abb. 7 im Anhang; Kubier et al 2020). Diese Werte schwanken zwischen < 0,2 µg/l und > 0,5 µg/l.…”

“…Einige Geesten haben ungewöhnlich geringe Hintergrundwerte mit Cd < 0,1 µg/l, die im Bereich der Hintergrundwerte der Marschen und vieler Niederungen liegen, was zeigt, dass diese Geesten als Moor-Geesten bzw. Übergang zum Bergland einen anderen hydrogeologischen und hydrochemischen Charakter haben (Kubier et al 2020).…”

Manganese (Mn) Concentrations and the Mn-Fe Relationship in Shallow Groundwater: Implications for Groundwater Monitoring

“…Groundwater in the lowlands and the Geesten is predominantly of the alkaline-earth type with lower bicarbonate contents. Groundwater in the uplands appears to be oxic and was labeled as bicarbonate dominated and bicarbonatic-sulfatic alkaline-earth [15].…”

Grafting chelating groups on 2D carbon for selective heavy metal adsorption

“…Heavy metals are naturally present in groundwater, 4,5 which has caused severe health problems for 6 million people all over the world. [6][7][8][9][10][11] Therefore, heavy-metal removal methods which are cheap, convenient, and easy for treating daily drinking water are critical. So far, heavy metals in water have been removed by ion exchange, 12 precipitation, 13 reverse osmosis, 14 electrochemical treatment, 15 and adsorption.…”