1 Advances in Managed Aquifer Recharge

This session will present an interdisciplinary overview of the hydrological, geochemical, and geobiological processes and interactions associated with the practical implementation and operation of managed aquifer recharge strategies.

Sunday, 19 October 2025
8:00 AM - 12:00 PM
HBGCC, 209

Trace element geochemistry of carbonates and organic layers from continuous cores C38S, L63N, L63S, and C59. Insights into the Lake Okeechobee watershed restoration aquifer storage and recovery project

Paper number: 1-4
Program: Technical Sessions
Time: 8:55 AM – 9:10 AM

Authors

Abstract

Four continuous cores were recovered north of Lake Okeechobee, Florida, as part of the Comprehensive Everglades Restoration Plan. These cores recovered rocks from the Suwannee Limestone and Ocala Limestone of the upper Floridan aquifer, the Avon Park Formation of the Avon Park permeable zones, and numerous confining units. As part of a larger study to help identify locations for ASR wells, whole-rock XRF and ICP-MS were conducted on 40 samples from the cores ΜΆ  19 from carbonates and 21 from interbedded organic layers. Carbonate samples from the Suwannee Limestone and Ocala Limestone plot near the calcite endmember on the carbonate classification diagram. Avon Park Formation samples plot near the dolomite endmember. The Suwannee Limestone has As between 7-9 ppm, Mo between 2-8.3 ppm, and FeOT between 0.19-0.23%. The Ocala Limestone has As between 0.6-9.3 ppm, Mo between 1.5-36.3 ppm, and FeOT between 0.09-0.19%. The Avon Park Formation has As between 0.2-4.6 ppm, Mo between 4-195.1 ppm, and FeOT between 0.06-0.25%. An organic layer from the Suwannee Ls. has As = 64 ppm, Mo = 151 ppm, and FeOT = 0.32%. Five organic layers from the Ocala Limestone have As between 5-383 ppm, Mo between 9-10,368 ppm, and FeOT between 0.15-0.32%. Fifteen organic layers from the Avon Park Formation have As between 1-117 ppm, Mo between 40-2,914 ppm, and FeOT between 0.14-1.52%. The Suwannee Limestone, Ocala Limestone, and Avon Park Formation have high Y/Ho, low Ce/Ce*, and high La/La* suggesting open ocean settings. However, the organic layers from these same units have low Y/Ho, high Ce/Ce*, and low La/La* suggesting continental detritus input (aeolian).

The organic layers have As, Mo, and FeOT higher than the interbedded carbonates. Fe is commonly associated with atmospheric dust  deposition. The high Fe, low Y/Ho, high Ce/Ce*, and low La/La* suggests the organic layers were derived through terrestrial sedimentation (aeolian)  into the marine depositional settings. Avon Park Formation detrital zircons (n = 13) ranging in age from 192 to 2647 Ma supports a terrestrial input. Organic layers in the flow zones should be avoided during ASR due to their high metal concentrations and potential to release these metals during water storage.     

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412162

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