Hydrogeochemical Characteristics of Dripwater in Jiguan Cave, Henan Province at Different Scales and the Response to Regional Extreme Drought Event
2017, 32 (10):
Geochemical dynamics of dripwater at LYXS and TGBD in Jiguan Cave were monitored from October 2009 to December 2015, and the rainstorm from August 4th to 6th in 2015 was monitored. Characteristics of the dripwater, including dripping speed, pH value, HCO-3, electrical conductivity, Ca2+, Mg2+, Ba2+, Sr2+, element ratio, and its relationship with precipitation, were analyzed at different time scales, and their responses to the extreme drought events were analyzed. The results showed that: 1) At inter-annual scale, the hydrochemical characteristics of dripwater responded to the precipitation difference between wet years and dry years. It was mainly controlled by the dissolution of soil CO2, leaching effect and the intensity of prior calcite precipitation (PCP) effect. 2) Affected by the migration path of karst water, the leaching effect, the time of water-rock interaction and the PCP effect, there were obvious seasonal variations of the characteristics of dripwater. 3) At single rainfall scale, the hydrochemical characteristics of dripwater varied with the dripping rate. It was mainly influenced by the migration path of karst water, piston effect and dilution effect and had little relation with the time of water-rock interaction. 4) Affected by retention of the old water in the extreme drought year of 2013 and the dilution effect of the new precipitation in 2014, the extreme values of the hydrochemical indicators appeared in 2014 when the precipitation rebounded. The decrease rates of EC, HCO-3, Ca2+, Mg2+, Ba2+, Sr2+, were 12%, 35%, 35%, 28%, 89% and 95%, respectively.
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