Year 4 Research Fate of CCA-Treated Wood

n Evaluate Fate of Wood Treated With Preservative Chemicals ä Evaluate CCA- and alternative-chemical- treated wood through TCLP and SPLP (Phase I) ä Evaluate arsenic species in leachates collected from landfills (Phase II) Objectives Note: Complimentary Study on Chromium Speciation

Phase I: Leaching of Alternative- Chemical Treated-Wood Products n Samples Include ä ACQ-Treated Wood ä CBA “ “ ä CC “ “ *** ä CDDC “ “ ä CCA “ “ Treated Through Facility A ä CCA “ “ Treated Through Facility B ä Untreated Wood ä Unknown Treated Wood (?)

Sample Processing n 8, 2”x4”x16 ft were purchased

Analytical Methods for Alternative Chemicals n Description of Leaching Test Plan n Review of existing methods for analysis of alternative chemicals (AWPA, EPA, and others) n Proposed methods of analysis n Questions for TAG

Plan for Leaching n Primary Leaching Tests ä TCLP ä SPLP n Additional Leaching Tests ä Deionized/Distilled Water ä Synthetic Seawater

Leaching Tests Wood Sample Size reduced following standard leaching protocols Leaching Test 18 hour contact, 20:1 Liquid to Solid ratio, Rotary extraction Leachate Analysis Leachate analyzed using standardized methods

Methods of Analysis n Sources of methods: ä AWPA Standards ä EPA Methods ä Instrument Manufacturer Methods ä Other n Methods are often matrix specific ä The matrix of interest in the this study is aqueous leaching fluid

Chemicals to be Analyzed CC CCA ACQ CBA CDDC As, Cr, Cu Cu Cu, B Cu -- DDAC Tebuconazole Dimethyldithio- carbamate Citrate Preservative Inorganic Chemical(s) Organic Chemical(s)

Inorganic Methods ICP-AES FLAA GFAA 6010B A21-93 A11-93 Analytical Method EPA Method AWPA Standard Note: Methods may require extraction or digestion depending on the matrix or method

Organic Chemical Analysis Citrate DDAC CDDC Tebuconazole HPLC, GC Colorimetric HPLC,Titration UV Spec A16-A/17-97 A25-94 * A23-94/A24-94 A2-98 Organic Chemical Analytical Technique AWPA Method (liquids)

Other Analytical Methods n Citrate by Ion Chromatography ä Dionex methods manual n Alternative Titration for DDAC ä Manufacturer suggestion

Proposed Methods n Methods selected based on resources available, time constraints, and analytical objectives

Analysis of Inorganic Chemicals n Copper and Boron will be analyzed using ICP, FLAA, or GFAA following US EPA methods (including acid digestion).

ICP

Perkin-Elmer 5100 FLAA/GFAA

Analysis of Tebuconazole n A GC/MS will be used for analysis. n Based on a modified version of AWPA method A24-94 n Detection limit is approximately 100  g/L

Trace 2000 GC/MS

Analysis of DDAC (ACQ) n A two-phase titration analysis will be performed following method A17-97.

Titration Setup

Analysis of CDDC n Analysis will be performed using a colorimetric method specified in A25-94 and instrument methods manual.

Hach DR/4000U Spectrophotometer

Analysis of Citrate n Analysis will be performed using Ion Chromatography

Dionex DX-500 Ion Chromatograph

Chromatogram

Other Possibilities n Toxicity Tests ä MET-plate ä Microtox ä Algal assay ä Yeast assay

Questions for TAG n Are we missing any analytes of concern? n Suggestions on methods? n Comments on leaching tests?

Bernine Khan University of Miami Arsenic: Arsenic: Toxicity, Mobility & Analytical Methods for Speciation

Part I - Characteristics Arsenic Species Arsenic Toxicity Arsenic Mobility Part II - Arsenic Speciation Study Purpose of Study Goals for Year 4 Hydride Generation Method - SDDC Outline

Definition Various species of an element which make up the total concentration of that element - different oxidation states (e.g. arsenic +3, +5, -3) inorganic - contains sulfur organic - contains carbon/hydrogen groups Speciation

Why are we interested in speciation? Not all species are toxic Total concentration - over-/under-estimate toxicity Standards EPA’s MCL for DW- 50  g/L (5  g/L) As TCLP limit  g/L Speciation

Arsenic Species AsH 3 - arsine (gas) As(III) - inorganic arsenite As(V) - inorganic arsenate MMAA - monomethylarsonic acid DMAA - dimethylarsinic acid TMAO - trimethylarsine oxide AsB - arsenobetaine (marine) * AsC - arsenocholine (marine) * Decreasing Toxicity

Arsenic Species AsH 3 - arsine (gas) As(III) - inorganic arsenite As(V) - inorganic arsenate - CCA MMAA - monomethylarsonic acid DMAA - dimethylarsinic acid TMAO - trimethylarsine oxide AsB - arsenobetaine (marine) * AsC - arsenocholine(marine) * Decreasing Toxicity

Arsenic Species AsH 3 - arsine (gas) As(III) - inorganic arsenite As(V) - inorganic arsenate MMAA - monomethylarsonic acid DMAA - dimethylarsinic acid TMAO - trimethylarsine oxide AsB - arsenobetaine (marine)* AsC - arsenocholine (marine)* Decreasing Toxicity

Arsenic Species AsH 3 - arsine (gas) As(III) - inorganic arsenite As(V) - inorganic arsenate MMAA - monomethylarsonic acid DMAA - dimethylarsinic acid TMAO - trimethylarsine oxide AsB - arsenobetaine (marine)* AsC - arsenocholine (marine)* Decreasing Toxicity

Toxicity Data Arsenic Compound Inorganic arsenite [As(III)] Inorganic arsenate [As(V)] MMAA - monomethylarsonic DMAA - dimethylarsinic acid TMAO - trimethylarsine oxide AsB - arsenobetaine (marine) AsC - arsenocholine (marine) LD 50 (mg/kg) ,800 1,200 10,600 10,000 6,000 Animal rat mouse LD 50 - concentration at which 50% of a population dies. Low LD 50 - more toxicHigh LD 50 - less toxic

Arsenic Mobility Reducing O 2 & Eh As(V) +5 As(III) +3 As(III) +3 AsH 3 (aq) AsS +3 As Most surface waters Most ground waters pH Eh (volts) Eh-pH diagram measure of system state (aerobic/ anaerobic) As(III) - Oxidized As(V) - Reduced Methylation

Hyphenated techniques Separation + detection methods Separate As(III) and As(V) from interfering ions Detection methods - detect & quantify Part II Arsenic Speciation Study

Purpose of Study CCA treated wood disposed of in unlined C&D landfills Leaching studies show significant amounts of CCA leaching from wood under varying pH solutions Determine the total arsenic & individual concentration of As(III) & As(V) species Chemical Hydride Generation method

Leaching Study Leaching Study (Warner et al. 1990) Arsenic leaching increases linearly with decreasing pH Buffer pH % As citric acid/NaOH citric acid/NaOH citric acid/NaOH citric acid/NaOH distilled water borax/HCl Buffer pH % As H 2 SO H 2 SO H 2 SO Arsenic after 40 days - retention of 1.99 kg/m 3 in new wood

Goals for Year 4 Current Study: Analysis of As(III) & As(V) by Chemical Hydride Generation (CHG) method SDDC - CHG method chosen - NaBH 4 to reduce arsenic to its gaseous form (arsine) so as to be detected SDDC method - Test reproducibility using standard solutions

Silver Diethyldithiocarbamate (SDDC) Method Current Study ug

Results of SDDC Methods Absorbance Conc. (  g) Absorbance Conc. (  g) Arsenite [As(III)]

As(III) Calibration Curve

Results of SDDC Methods Absorbance Conc. (  g) Absorbance Conc. (  g) Arsenate [(As(V)]

As(V) Calibration Curve

Goals for Year 4 Next Steps: Determine how best to preserve sample Analyse GW samples near C&D landfills Analyse leachate from MSW and C&D(?) landfills

Speciation of Chromium

Chromium Speciation n Background n Methods of Analysis n Proposed Methodology

Chromium Exists as Several Chemical Species Most common oxidation states: 0, +3, +6 0: Elemental Chromium (Cr) +3: Trivalent Chromium Species: Cr +3, Cr 2 O 3 +6: Hexavalent Chromium Species: CrO 4 2-, Cr 2 O 7 -

Chromium Speciation Important! n The characteristics and properties of trivalent chromium and hexavalent chromium are greatly different. n Cr(VI) is much more toxic and mobile than Cr(III)

Difference between Cr(VI) and Cr(III) Factored into Regulations RCRA Regulations 40 CFR 261.4(b)(6)(i) A solid waste that is a characteristic or listed hazardous waste solely because of chromium is not hazardous if…..

– (A) The chromium in the waste is exclusively (or nearly exclusively) trivalent chromium; and – (B) The waste is generated from an industrial process which uses trivalent chromium exclusively (or nearly exclusively) and the process does not generate hexavalent chromium; and – (C) The waste is typically and frequently man-aged in non-oxidizing environments.

n Ingestion: ä Cr(III): 78,000 mg/kg ä Cr(VI): 390 mg/kg

Cr(III) versus Cr(VI) n Hexavalent chromium exists in alkaline, strongly oxidizing environments n Trivalent chromium exists in moderately oxidizing and reduced environments

pH Eh (V) Cr 2 O 3 CrO 4 2- Cr 2 O 7 - Cr 3+

pH Eh (V) Cr 2 O 3 CrO 4 2- Cr 2 O 7 - Cr 3+

Chromium in Wood Preservation n The chromium in CCA preservative solution is hexavalent chromium. n Upon fixation in the wood, Cr(VI) becomes converted to Cr(III)

When Might Cr(VI) Be Encountered? n If wood is improperly fixed (as a result, for example, of inadequate fixation time at low temperatures) n When in contact with oxidizing chemicals such as deck brighteners

Oxidation of Chromium in the Environment n In the natural environment, chromium tends to exist as Cr(III) n Oxidation of Cr(III) to Cr(VI) as a result of manganese (hydr)oxides

Methods of Cr(VI) Analysis n Typical chromium measurements are total chromium (Cr(III) + Cr(VI) + other) n Methods have been developed for Cr(VI) analysis n Sample holding time is minimal

Methods of Cr(VI) Analysis n Solvent extraction followed by total chromium analysis n Colorimetric Determinations n Chromatographic Determinations

Selected Method n Ion Chromatography

Research Project: Assessing the Impact of Chromium in the Environment n Funding provided by Florida Department of Environmental Protection

Tasks 1. Literature Review 2. Assessment of pH and ORP as indicators or Cr speciation 3. Evaluate kinetics of conversion of Cr(VI) to Cr(III) in natural soils 4. Develop guidance document

Additional Tasks 5. Examine Cr(VI) in ash from combustion of wood containing CCA-treated wood 6. Examination of Cr(VI) formation potential in C&D debris disposal environments

Previous Research n In year 2, wood ash containing CCA-treated wood was found to leach chromium in an unpredictable manner (relative to arsenic)

Arsenic Leaching from Wood Ash TC (5) GWCTL (0.05)

Chromium Leaching from Wood Ash TC (5) GWCTL (0.10)

Questions