Exploring soluble and colloidally transported trace elements in stalagmites: The strontium-yttrium connection

Climatic and cave setting influences on drip water fluorescent organic matter over an annual cycle in Northwestern Spain and implications for fluorescent laminations in stalagmites

“…From each location, samples for fluorescence measurements have been collected directly into amber glass vials, which were previously combusted for 4 hours at 450°C. In a separate study (Kost et al, 2022), splits of water samples on the same day and location were analyzed for stable isotopes, trace elements, carbon isotopic ratio of dissolved inorganic carbon (DIC) and cave conditions (Temperature, RH, pCO2) were recorded. The samples were shipped to ETH Zurich and stored in the dark at 4°C before measurement.…”

“…Given the length of the entire time series (only one year), longterm trends and interannual variability cannot be evaluated. The bi-weekly or monthly sampling is also not designed to capture the effect of fast-changing fissure flows; however, with one exception (FOR), the sampled sites are classified at the boundary between seepage flow and seasonal drip based on the variation in drip rate, suggesting a dominant matrix flow component (Kost et al 2022).…”

“…In this setting, the variance of drip water d 18 O may be useful indicator of drip water residence time (Kost et al 2022). This is because individual rain events feature considerable d 18 O variability (Stoll et al, 2015;Moreno et al, 2020), but mixing within the karst reservoir leads to dampening of this signal to varying degrees at different drip sites.…”

“…From in-situ techniques, fine (5 to 1000 micron) scale alternations of high-and low fluorescence intensity perpendicular to the growth axis, have been described from many stalagmites from mid-latitude regions and this layering has been demonstrated to be annual in many cases (Baker et al, 2008;Proctor et al, 2000). The fluorescent layer intensity complexly interacts with speleothem trace element chemistry (Huang et al, 2001;Sliwinski et al, 2022). In such stalagmites, several authors have suggested the seasonal peak in fluorescence intensity is due to an increased in-flux of dissolved organic matter (DOM) in drip waters during increased autumn leaf litter and rainfall (Borsato et al, 2007;Kwiecien et al, 2022;McGarry and Baker, 2000), or alternately due to fine soil blown into the cave as an aerosol (Fairchild and Baker, 2012;Luetscher et al, 2021).…”

“…In such stalagmites, several authors have suggested the seasonal peak in fluorescence intensity is due to an increased in-flux of dissolved organic matter (DOM) in drip waters during increased autumn leaf litter and rainfall (Borsato et al, 2007;Kwiecien et al, 2022;McGarry and Baker, 2000), or alternately due to fine soil blown into the cave as an aerosol (Fairchild and Baker, 2012;Luetscher et al, 2021). In addition to changes in DOM input, changes in adsorption behavior at the crystal level, induced by variations in environmental and cave conditions such as pH, redox state and cave ventilation, could also cause variations in the incorporation of the fluorescent DOM ( (Ramseyer et al, 1997;Sliwinski et al, 2022). Where the processes driving fluorescent layers can be demonstrated to be annual, then fluorescent banding can be exploited as a paleo-seasonality indicator (Ramseyer et al, 1997;Blyth et al, 2008;Sliwinski and Stoll, 2021;Orland et al, 2012) or to improve age models through fluorescent layer counting (Kwiecien et al, 2022).…”