Arsenic speciation in Arsenic speciation in Soil and SedimentSoil and Sediment

Myron GeorgiadisMyron Georgiadis

Florida International University

TAG Meeting January 10, 2003

BackgroundsBackgrounds

Leaching occurs from CCA-Treated Wood Leaching occurs from CCA-Treated Wood into soil and sedimentsinto soil and sediments

Traditional methods for arsenic analysis in Traditional methods for arsenic analysis in soil - Digestionsoil - Digestion

Develop an extraction method for Arsenic Develop an extraction method for Arsenic in soils and sediments while preserving in soils and sediments while preserving the species.the species.

Method DevelopmentMethod Development

Reference Soil PACS2Reference Soil PACS2PACS2 – Marine Sediment Reference Material PACS2 – Marine Sediment Reference Material from National Research Council Canadafrom National Research Council Canada

Extraction Solution: pH, Buffer Capacity, Extraction Solution: pH, Buffer Capacity, Chemical InteractionsChemical Interactions

PACS2 was extracted with a phosphate PACS2 was extracted with a phosphate buffer.buffer.

Analyzed by HPLC-HG-AFS. Analyzed by HPLC-HG-AFS.

0

1

2

3

4

5

6

7

8

9

1 3 5 12 24Time Extracted (hours)

Co

nc

. (m

g/g

)

As(III) As(V)

Arsenic Concentration vs TimeArsenic Concentration vs Time

- Conversion of As(III) to As(V).

- Reabsorption back into soil.

Approaches Approaches

Potential Effect of Fe and MnPotential Effect of Fe and Mn

Extract with EDTA to remove metals from Extract with EDTA to remove metals from solution which may aid in the solution which may aid in the interconversioninterconversion

Provide a reducing environment using Provide a reducing environment using hydroxylaminehydroxylamine

Use of Complexing Reagent NaDDC and Use of Complexing Reagent NaDDC and APDCAPDC

Potential Effect of Fe and MnPotential Effect of Fe and Mn

0.00

0.50

1.00

1.50

2.00

2.50

1 3 5 12 24

Extraction Time (Hours)

Co

nc

(mg

/g)

As(III) As(V)

Extraction with EDTAExtraction with EDTA

PACS2 Extraction with PO4 + EDTA

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

1 3 5 12 24Time Extracted (Hours)

Co

nc

(mg

/g)

As(III) As(V)

Use of HydroxylamineUse of Hydroxylamine

0.E+00

5.E+05

1.E+06

2.E+06

2.E+06

3.E+06

3.E+06

4.E+06

4.E+06

5.E+06

0 24

Time (Hours)

Pea

k A

rea

As(III) As(V)

Use of HydroxylamineUse of Hydroxylamine

Arsenite stability over a period of 24 hours with and without 1% Hydroxyl Amine

50ppb Spiked Arsenite

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

0 24Time (Hours)

Co

nc

(pp

b)

PO4 NH2OHAs(III)

Complexing Reagents Complexing Reagents

Sodium diethyldithiocarbamate Sodium diethyldithiocarbamate trihydratetrihydrate (NaDDC) (NaDDC)

Ammonium pyrrolidine Ammonium pyrrolidine dithiocarbamatedithiocarbamate (APDC)(APDC)

Arsenic Concentrations in Arsenic Concentrations in Marine Organisms Attached to Marine Organisms Attached to

CCA-treated WoodCCA-treated Wood

Organisms analyzedOrganisms analyzed: : soft coral, hydroids, soft coral, hydroids, crabs, barnacles, orange sponge, yellow crabs, barnacles, orange sponge, yellow sponge, black sponge, oyster, tube worm, sponge, black sponge, oyster, tube worm, amphipods, starfish, unknown invertebrate amphipods, starfish, unknown invertebrate (black outer layer, soft inner)(black outer layer, soft inner)

Hydroids and amphipods showed elevated Hydroids and amphipods showed elevated arsenic concentration for those collected from arsenic concentration for those collected from on CCA-woodon CCA-wood

As Speciation: standardsAs Speciation: standards

0 200 400 600 800 1000 1200 1400 1600 1800 2000

2500

5000

[2] TIC:45558.D [Count]

sec->

10 ppb standards

1

23

4

5

1. AsB; 2. As(III); 3. DMA; 4. MMA; 5. As(V)

As speciation: Hydriods on Concrete As speciation: Hydriods on Concrete PilingsPilings

0 200 400 600 800 1000 1200 1400 1600 1800 2000

1000

2000

[2] TIC:45584.D [Count]

sec->

AsB Unknown 1

AsCAs(III)

DMA

Unknown 2

Unknown 3 or MMA

As(V)

As speciation: Barnacle on OLD RSMAS As speciation: Barnacle on OLD RSMAS PierPier

AsCAs(III)

DMA

Unknown 2

Unknown 3 or MMA

As(V)

0 200 400 600 800 1000 1200 1400 1600 1800 2000

2500

5000

[2] TIC:45570.D [Count]

sec->

AsB

Unknown 1

AsC As(III)Unknown 2

Unknown 4 As(V)

AcknowledgementsAcknowledgements

Dr. Helena Solo-GabrieleDr. Helena Solo-Gabriele

Dr. Pat WalshDr. Pat Walsh

Dr. Greg MayerDr. Greg Mayer

Dr. John BarimoDr. John Barimo

Ms. Zhangrong ChenMs. Zhangrong Chen

Mr. Myron GeorgiadisMr. Myron Georgiadis