Occurrence, reaction and transport behavior of cadmium in groundwater

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.