Long-Distance Cavernous Flow in the Upper Florida Aquifer, Woodville Mantled-Karst Plain, Leon and Wakulla Counties, Florida
Publication Date: 2024/12/01
Publication Volume: Journal of Cave and Karst Science 86 #
Publication Keywords: Rhodamine WT dye study, Floridan Aquifer, Aquifer contamination
ABSTRACT:
A Rhodamine WT dye study was conducted to establish whether a subterranean flow could be positively demonstrated between Lake Jackson, a shallow perched lake, and Wakulla Spring, a renowned first magnitude spring. The lake is 30.6 km north of the Spring and 8 km north of Tallahassee, Florida. Dye was injected into a lake-bottom sinkhole on September 19, 2017, for 6.5 min. The main distinctive dye concentration peaks were recorded by sondes located at both Wakulla Spring and nearby Sally Ward Spring after 35 days. Charcoal packs deployed at these two springs and three others nearby also encountered dye within time intervals consistent with the recorded breakthrough events measured by the sondes, all of which were of short duration ranging from 1 min to 100 min. These results indicate that some of the injected dye made its way to several Wakulla County springs via an aquifer conduit-like system dominated by advection within which water flowed at an average speed of 0.8 km d−1. Dye detection at five well-separated springs further indicates that the conduit system is both braided and branching. Although these results show a connection between Lake Jackson and several Wakulla County springs and point to a leaky-conduit flow able to transport nutrients and pollutants rapidly over long distances, another important conclusion of the study is that, overall, very little of the dye injected into the lake-bottom sinkhole made it to Wakulla Spring. This indicates that most of the dye dispersed into the limestone matrix. This study has been exploratory in design and only allows conjectural statements on the actual dye-mass balance.
SIMPLE LANGUAGE SUMMARY:
Scientists studied how water moves underground in Florida, between a lake called Lake Jackson and a famous spring called Wakulla Spring. They wanted to see if water from the lake travels to the spring through hidden underground channels called conduits. To test this, they added a harmless pink dye to the lake and tracked where it went. After about a month, they found small amounts of the dye in Wakulla Spring and a few other nearby springs, showing that some water from the lake does flow there. However, most of the dye didn’t reach the spring—it got soaked up into the porous limestone underground or went into other unseen channels. This study helps scientists understand how pollution could quickly spread through these underground water systems and how we can better protect Florida’s springs.
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