Paper No. 224-10
Presentation Time: 10:40 AM
GEOCHEMICAL ANALYSIS OF A CONTINUOUS CORE C38S RECOVERED FROM THE LAKE OKEECHOBEE WATERSHED RESTORATION PROJECT AQUIFER STORAGE AND RECOVERY WELLS: A NOVEL APPROACH FOR MANAGEMENT OF METAL UPTAKE
KASSIS, Zoie1, MACDONALD Jr., James2, MISSIMER, Thomas1, GIRIMURUGAN, Senthil Balaji3, CHOU, Ju4, GRIMM, Hanna5, ROTZ, Rachel6, AURELIO, R. Peter7, MOREJON, Sophia7 and LENTZ, Evan S.7, (1)U. A. Whitaker College of Engineering, Florida Gulf Coast University, 10561 FGCU Boulevard South, Fort Myers, FL 33965-6565, (2)Environmental Geology Program and Honors College, Florida Gulf Coast University, 10501 FGCU Blvd. South, Fort Myers, FL 33965-6565, (3)Department of Mathematics, Florida Gulf Coast University, 10501 FGCU Blvd S, Fort Myers, FL 33965, (4)Department of Chemistry and Physics, Florida Gulf Coast University, 10501 FGCU Blvd South, Fort Myers, FL 33965, (5)The Water School, Florida Gulf Coast University, 10501 FGCU Boulevard South, Fort Myers, FL 33965, (6)The Water School, Florida Gulf Coast University, 10561 FGCU Boulevard South, Fort Myers, FL 33965-6565, (7)Environmental Geology Program, Florida Gulf Coast University, 10501 FGCU Blvd S, Fort Myers, FL 33965
Aquifer storage and recovery (ASR) wells along Lake Okeechobee have been proposed as part of the Comprehensive Everglades Restoration Plan. However, researchers have linked elevated concentrations of As, Hg and transition metals in groundwater because of ASR in carbonate rocks. Approximately 909 feet of continuous core (C38S) was recovered along the Kissimmee River north of Lake Okeechobee. Using handheld X-ray fluorescence, the core was analyzed at approximately every foot to determine the concentrations of metals and other elements. Within this continuous core three flow zones were identified. Two flow zones are located in the Upper Floridan Aquifer (UFAFZ1 & UFAFZ2) and one is located lower in the Floridan (Avon Park Permeable Zone [APPZ1]). The importance of this study will guide the design of future ASR wells to avoid aquifer zones with high concentrations of metals that could become mobile during water storage.
Geochemical analysis of C38S has revealed the averages for UFAFZ1 in the Suwanee and Ocala Limestones are As: 7.04 ppm; Mo: 8.13 ppm; Hg: 7.20 ppm; Cr: 78.2 ppm; Cu: 20.3 ppm; Cd: 25.9 ppm; Ni: 23.7 ppm; and, V: 7.27. Average concentrations in UFAFZ2 in the Ocala Limestone are As: 43.9 ppm; Mo: 70.6 ppm; Hg: 10.4 ppm; Cr: 88.5 ppm; Cu: 55.4 ppm; Cd: 26.8 ppm; Ni: 26.8 ppm; and, V: 16.74. The APPZ1 in the Avon Park Formation averages are As: 230 ppm; Mo: 86.2 ppm; Hg: 9.6 ppm; Cr: 75.6 ppm; Cu: 33.8 ppm; Cd: 25.3 ppm; Ni: 27.3 ppm; and, V: 16.39.
C38S is comparatively shallower than a previously analyzed adjacent core L63N (1500 ft.). Similar to C38S, the UFAFZ for L63N average concentrations were lower As: 7 ppm; Mo: 107 ppm; Hg: 8 ppm. The average concentrations for the APPZ1 for L63N were higher As: 215 ppm; Mo: 175 ppm; Hg: 9 ppm. Organic layers in both cores have higher metal concentrations. The elevated As, Mo, and Hg in both cores could be the result of sulfide minerals and organic layers.
An ash layer at 1466 feet in core L63N, a potential marker bed in the Eocene Avon Park Formation, may also occur in C38S at 1408 ft depth.
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