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ARSENIC DETECTIONS IN GROUNDWATER AT C&D FACILITIES

ARSENIC DETECTIONS IN GROUNDWATER AT C&D FACILITIES. FDEP CCA TAG GW Subcommittee Steve Clarke, Chair - WM. Arsenic in Florida. How Does Arsenic Get in C&D Groundwater. Naturally Occurring? Releases from CCA Wood? Release from Pesticides? Mobilization of Naturally Occurring Minerals?

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ARSENIC DETECTIONS IN GROUNDWATER AT C&D FACILITIES

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  1. ARSENIC DETECTIONS IN GROUNDWATERAT C&D FACILITIES FDEP CCA TAG GW Subcommittee Steve Clarke, Chair - WM

  2. Arsenic in Florida

  3. How Does Arsenic Get in C&D Groundwater • Naturally Occurring? • Releases from CCA Wood? • Release from Pesticides? • Mobilization of Naturally Occurring Minerals? • Other?

  4. MOBILIZATION PROCESSES GROUNDWATER REDUCTION IRON MINERAL DISSOLUTION ARSENIC VREDUCTION As(V) As(III) As(V) GROUNDWATER OXIDATION FeAsS + 4O2 SO42- + As + Fe DISPLACEMENT BY OTHER ANIONS + (H2AsO4)- + (H2PO4)- (H2AsO4)- EXAMPLES: Oxygen removed by decay Low DO Water  Fe, As FeAsS in dredge sediments deposit on banks, oxidize  As Pesticides: As adsorbs to clays  Fertilizers: P replaces As  As LEGEND Soil mineral with positively charged surface sites + As(III) Arsenite As(V) Arsenate Reaction/process REVISION: 0 PLOT DATE: 12/10/03 DRAWN BY: ED

  5. MAJOR ARSENIC MOBILIZATION PROCESSES MAJOR ARSENIC IMMOBILIZATION PROCESSES GROUNDWATER OXIDATION AND RESORPTION GROUNDWATER REDUCTION IRON MINERAL DISSOLUTION ARSENIC VREDUCTION As(V)(H2AsO4)- + + As(V)(H2AsO4)- + As(V) As(III) As(V) As(V)(H2AsO4)- Iron Oxides PRECIPITATION GROUNDWATER OXIDATION 2As(III) + 3S As2S3(Orpiment) As(III) + S AsS (Realgar) FeAsS + 4O2 SO42- + As + Fe DISPLACEMENT BY OTHER ANIONS + (H2AsO4)- + (H2PO4)- (H2AsO4)- LEGEND Soil mineral with positively charged surface sites + As(III) Arsenite As(V) Arsenate Reaction/process

  6. Arsenic detections in GW, not associated w/metals

  7. Arsenic detections in GW, not associated w/indicators

  8. Arsenic detections in GWTracks Iron

  9. DRAFT= Arsenic detections in GW,not associated w/metals

  10. DRAFT Arsenic detections in GWnot associated w/indicators

  11. DRAFT Arsenic detections in GWTracks Iron

  12. Iron detections in GW

  13. Fe/As Detections Turbidity

  14. Arsenic detections in GW

  15. Questions to the TAG • How do we show that Arsenic is from • A release due to CCA Wood? • Mobilization of Naturally Occurring Minerals? • A Naturally Occurring/Other Source • Other?

  16. Moving Forward • Reevaluate As against select indicators • iron, sulfate, TDS, chlorides, turbidity, D.O., others?); • Categorize the types of detections; and • Consider next steps • Confirming the source (sampling); and • Evaluating the significance/extent (e.g. modeling?).

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