Details zur Publikation

Referenztyp Zeitschriften
DOI / URL Link
Titel (primär) Climate control of decadal-scale increases in apparent ages of eogenetic karst spring water
Autor Martin, J.B.; Kurz, M.J.; Khadka, M.B.;
Journal / Serie Journal of Hydrology
Erscheinungsjahr 2016
Department HDG;
Band/Volume 540
Sprache englisch;
POF III (gesamt) T32;
Keywords Groundwater recharge; Groundwater remediation; Florida karst; Springs; Water age; Atlantic multidecadal oscillation
UFZ Querschnittsthemen RU2;
Abstract Water quantity and quality in karst aquifers may depend on decadal-scale variations in recharge or withdrawal, which we hypothesize could be assessed through time-series measurements of apparent ages of spring water. We tested this hypothesis with analyses of various age tracers (3H/3He, SF6, CFC-11, CFC-12, CFC-113) and selected solute concentrations [dissolved oxygen (DO), NO3, Mg, and SO4] from 6 springs in a single spring complex (Ichetucknee springs) in northern Florida over a 16-yr period. These springs fall into two groups that reflect shallow short (Group 1) and deep long (Group 2) flow paths. Some tracer concentrations are altered, with CFC-12 and CFC-113 concentrations yielding the most robust apparent ages. These tracers show a 10–20-yr monotonic increase in apparent age from 1997 to 2013, including the flood recession that followed Tropical Storm Debby in mid-2012. This increase in age indicates most water discharged during the study period recharged the aquifer within a few years of 1973 for Group 2 springs and 1980 for Group 1 springs. Inverse correlations between apparent age and DO and NO3 concentrations reflect reduced redox state in older water. Positive correlations between apparent age and Mg and SO4 concentrations reflect increased water-rock reactions. Concentrated recharge in the decade around 1975 resulted from nearly 2 m of rain in excess of the monthly average that fell between 1960 and 2014, followed by a nearly 4 m deficit to 2014. This excess rain coincided with two major El Niño events during the maximum cool phase in the Atlantic Multidecadal Oscillation. Although regional water withdrawal increased nearly 5-fold between 1980 and 2005, withdrawals represent only 2–5% of Ichetucknee River flow and are less important than decadal-long variations in precipitation. These results suggest that groundwater management should consider climate cycles as predictive tools for future water resources.
ID 17875
dauerhafte UFZ-Verlinkung
Martin, J.B., Kurz, M.J., Khadka, M.B. (2016):
Climate control of decadal-scale increases in apparent ages of eogenetic karst spring water
J. Hydrol. 540 , 988 - 1001