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Arsenic speciation in Soil and Sediment

Arsenic speciation in Soil and Sediment. Myron Georgiadis. Florida International University TAG Meeting January 10, 2003. Backgrounds. Leaching occurs from CCA-Treated Wood into soil and sediments Traditional methods for arsenic analysis in soil - Digestion

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Arsenic speciation in Soil and Sediment

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  1. Arsenic speciation in Soil and Sediment Myron Georgiadis Florida International University TAG Meeting January 10, 2003

  2. Backgrounds • Leaching occurs from CCA-Treated Wood into soil and sediments • Traditional methods for arsenic analysis in soil - Digestion • Develop an extraction method for Arsenic in soils and sediments while preserving the species.

  3. Method Development • Reference Soil PACS2 • PACS2 – Marine Sediment Reference Material from National Research Council Canada • Extraction Solution: pH, Buffer Capacity, Chemical Interactions • PACS2 was extracted with a phosphate buffer. • Analyzed by HPLC-HG-AFS.

  4. Arsenic Concentration vs Time - Conversion of As(III) to As(V). - Reabsorption back into soil.

  5. Approaches • Potential Effect of Fe and Mn • Extract with EDTA to remove metals from solution which may aid in the interconversion • Provide a reducing environment using hydroxylamine • Use of Complexing Reagent NaDDC and APDC

  6. Potential Effect of Fe and Mn

  7. Extraction with EDTA

  8. Use of Hydroxylamine

  9. Use of Hydroxylamine As(III)

  10. Complexing Reagents • Sodium diethyldithiocarbamate trihydrate (NaDDC) • Ammonium pyrrolidine dithiocarbamate(APDC)

  11. Arsenic Concentrations in Marine Organisms Attached to CCA-treated Wood

  12. Organisms analyzed: soft coral, hydroids, crabs, barnacles, orange sponge, yellow sponge, black sponge, oyster, tube worm, amphipods, starfish, unknown invertebrate (black outer layer, soft inner) • Hydroids and amphipods showed elevated arsenic concentration for those collected from on CCA-wood

  13. 10 ppb standards 1 5 4 3 2 As Speciation: standards 1. AsB; 2. As(III); 3. DMA; 4. MMA; 5. As(V)

  14. As speciation: Hydriods on Concrete Pilings Unknown 1 AsB Unknown 3 or MMA Unknown 2 AsC As(V) As(III) DMA

  15. As speciation: Barnacle on OLD RSMAS Pier AsB Unknown 1 Unknown 3 or MMA Unknown 2 AsC Unknown 2 AsC As(V) As(III) Unknown 4 As(V) As(III) DMA

  16. Acknowledgements • Dr. Helena Solo-Gabriele • Dr. Pat Walsh • Dr. Greg Mayer • Dr. John Barimo • Ms. Zhangrong Chen • Mr. Myron Georgiadis

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