Monitoring Bunker Cave (NW Germany): A prerequisite to interpret geochemical proxy data of speleothems from this site

► Bunker Cave is a homogeneously ventilated cave with rather low pCO2. ► No direct response to precipitation is observed at any drip site. ► The karst aquifer is well mixed. ► Prior Calcite Precipitation (PCP) is identified during times of low discharge. ► δ18O values of drip water record inter-annual climate trends.