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Publication Date

January 2000

Abstract

Five stalagmite drip-waters in the Grotte de Villars, Dordogne, have been monitored from early 1997 to early 1998, for variations in discharge, major inorganic species and dissolved luminescent organic matter. When compared to surface precipitation, each drip-water has a subtly different response, both in terms of discharge variability and lag time between surface precipitation and drip rate response. Calculated water excess is shown to be important in determining drip-water discharge; during periods of soil moisture deficit, drip-waters either show no response to surface precipitation, or in the case of one sample station, respond only to high intensity and/or high quantity precipitation events. All drip-waters have a large storage component to their flow. Four sample stations have a similar hydrochemical and luminescence response, although the precise timing and magnitude of the responses may vary between drip sources that are <5 m apart. Drip-water luminescence intensity increases in winter and spring, and increases in discharge lag by 2 – 3 months, suggesting that the water in the rising limb and peak of the winter discharge comes from the stored groundwater component rather than a soil source. Drip-water strontium anti-correlates with luminescence and exhibits a strong (±100%) seasonal variation, with high-strontium waters derived from stored groundwater and is inferred to originate in localised Sr-rich primary components in the limestone. Drip-water conductivity reflects Ca-HCO3 variations and falls during late summer to autumn, which is inferred to result from increased calcite precipitation above the cave with enhanced degassing related to progressive drying of the aquifer. Drip-water magnesium (following removal of the marine aerosol component) is just above detection limits and does not show strong seasonal variations. Variations in solution Pco2 occur, with a particularly strong increase in early 1997. The various chemical trends are observed at a number of different sites despite a pronounced variatio

Notes

Hydrology and Earth System Sciences, Vol. 4, no. 3 (2000).

Keywords

Stalagmite, Dripwaters, Luminescence, Discharge, Major Ion Chemistry

Description

RDA

Subject: topical

Stalagmite; Dripwaters; Luminescence; Discharge; Major Ion Chemistry

Type

Article

Genre

serial

Identifier

K26-05665

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