Controls on the geochemistry of speleothem-forming karstic drip waters, PhD thesis, 2000, Tooth, A.

Research was performed at Crag Cave, Castleisland, southwest Ireland, and P8 Cave, Castleton, Derbyshire, in order to determine the main factors responsible for modifying rainwater geochemistry during flow through soil and karstic aquifer zones. Monitoring was performed on a daily basis in summer and winter at Crag Cave, and on a monthly basis over one year at P8 Cave. At both sites, biannual peaks in karst system Ca2+ concentrations occurred due to: (i) promotion of microbial CO2 production by increased summer temperatures, and (ii) retardation of gaseous exchange by ponding of elevated winter rainfall input leading to an unseasonable build up in soil zone CO2. Therefore, speleothems at both sites may form biannual bands in hydrological years subject to elevated winter rainfall input.

In addition to variations in carbonate weathering due to fluctuations in CO2 levels, cation yields in Crag Cave matrix soil water were controlled by dolomite dissolution (Mg2+), plant uptake (K+), and evapotranspiration balanced by enhanced winter marine aerosol input (Na+). Strontium isotope analysis indicates that Sr2+ was derived from a 50:50 silicate/carbonate mixture, whereas the relatively light ?13C signal was related to direct evolution of CO2 into the aqueous phase in water-logged pores.

Within the Crag Cave aquifer variations in karst water geochemistry were controlled by dilution, flow switching, prior precipitation of calcite, and dolomite dissolution along the flow path. Strontium isotope analysis indicates that dissolution in the aquifer dominated, with Sr2+ being sourced from a 25:75 silicate/carbonate mixture. Light karst water 13C values were constrained by the supply of light soil gas to the aquifer.

Elevation in the Mg/Ca and Sr/Ca ratios in the Crag Cave speleothem record compared to present day analogues indicates that the former Holocene climate was drier, whereas heavier 87Sr/86Sr ratios and 13C values suggest variation in soil hydrology over time.

Soil and karst aquifer hydrological controls on the geochemical evolution of speleothem-forming drip waters, Crag Cave, southwest Ireland, 2003, Tooth Anna F. , Fairchild Ian J. ,

In recent years there has been increased interest in cave speleothems as archives of palaeoclimate. Monitoring of rainfall and soil and karst water chemistries was performed at Crag Cave, Castleisland, Co. Kerry, southwest Ireland, in August 1997 and January 1998 in order to understand temporal and spatial variations in karst water hydrology and chemistry and their implications for interpreting the potential palaeohydrological signal preserved by speleothems at this site. Temporal variations in karst water drip rates and geochemistry allow drips to be classified by hydrological response to rainfall and the associated processes of dilution, piston flow, source change and prior calcite precipitation during aquifer throughflow. Evolution from soil matrix and preferential flow solutions has also been determined to exert an important control on karst water chemistries. As a result of these findings we present hydrogeochemical models and plumbing diagrams that delineate the controls on karst water evolution at a number of sampling locations within the cave at this site. We propose that a palaeohydrological signal may be recorded by Crag Cave speleothems that may be interpreted via the study of Mg/Ca ratios in speleothems linked to monitoring of modern drip water chemistry