Presentation for NDIA's 30th Environmental & Energy Symposium ...

Presentation for NDIA's 30th Environmental & Energy Symposium ...

Defending the Rights of Metals: How to Distinguish Naturally High Groundwater Concentrations from SiteRelated Contamination Karen Thorbjornsen and Jonathan Myers, Ph.D. Shaw Environmental, Inc. Typical Definitions of Metals Contamination in Groundwater Concentrations that exceed MCLs Concentrations that exceed riskbased screening levels Concentrations that exceed background screening values, or fail other statistical comparisons to background data sets 2 Typical Definitions of Metals Contamination in Groundwater Chromium in Unfiltered Groundwater, Sewage Treatment Site, Alabama

10000.0 1000.0 100.0 10.0 CHROMIUM (ug/L) 1.0 0.1 BG(n=424; ND=63%) Site(n=18; ND=25%) 3 Problems With These Standard Approaches Trace elements in groundwater can have naturally large ranges (3 to 4 orders of magnitude) Distributions are highly skewed (lognormal)

Insufficient number of background samples Unequal sample sizes (site [n] >> background [m]) Geochemical processes are ignored 4 Unnecessary monitoring, risk assessment, or remediation can ensue if metals in site groundwater are erroneously identified as contaminants. Geochemical evaluation should be performed to properly distinguish actual contamination from naturally high background. 5 Reasons for Elevated Metals Concentrations in Groundwater Suspended particulates

Reductive dissolution pH effects Contamination 6 Effects of Suspended Particulates Most common suspended particulates in groundwater are clay minerals, hydrous aluminum oxides, aluminum hydroxides; and iron oxides, iron hydroxides, iron oxyhydroxides In neutral-pH water, Al concentrations > 1 mg/L indicate suspended Al-bearing minerals (clays) () surface charge

In neutral-pH, moderate to oxidizing redox conditions, Fe concentrations > 1 mg/L indicate suspended iron oxides (+) surface charge 7 Effects of Suspended Particulates Trace elements are associated with specific suspended particulates, yielding good correlations for trace-vs.-reference element concentrations in uncontaminated samples Oxyanionic elements negatively charged speciation under oxidizing conditions Arsenic (V): HAsO42, H2AsO4 Antimony (V): Sb(OH)6 Selenium (VI): SeO42 Vanadium (V): H2VO4, HVO42

Iron oxides (Fe) 8 Effects of Suspended Particulates Cationic elements positively charged speciation Barium: Ba2+ Lead: Pb2+ Nickel: Ni2+ Zinc: Zn2+ Clays (Al) and/or manganese oxides (Mn) Mixed elements multiple charges at equilibrium Chromium (III): Cr(OH)2+, Cr(OH)3o, Cr(OH)4 9 Effects of Reductive Dissolution

Releases of organic contaminants (fuel, solvents) can establish local reducing environments via anaerobic microbial activity These conditions drive the dissolution of iron oxides and manganese oxides, thereby mobilizing trace elements that were adsorbed on the oxide surfaces 10 Effects of Reductive Dissolution Identified by correlations of metals with indicators of local redox depression: Low ORP and DO Elevated dissolved Fe and Mn Lower sulfate and nitrate Detectable sulfide and ammonia Detectable hydrogen, methane, ethene, ethane Anaerobic Cl-solvent degradation products (cis-1,2-DCE, vinyl chloride) 11

Site 1 (Alabama): Aluminum vs. Iron in Unfiltered Groundwater n = 16 (m = 300) 1.E+08 R2 = 0.96 1.E+07 pH: 4.9 to 8.3 Aluminum (ug/L) 1.E+06 mean = 6.6 1.E+05 DO: 1.1 to 6.9 mg/L 1.E+04 mean = 5.2 mg/L 1.E+03 ORP: +148 to +272 mV

1.E+02 1.E+01 1.E+00 1.E+01 mean = +212 1.E+02 1.E+03 1.E+04 Iron (ug/L) 1.E+05 1.E+06 1.E+07 Background mV Site 12 Site 1 (Alabama): Unfiltered Aluminum vs. Filtered/Unfiltered Ratio

1.E+08 Unfiltered Aluminum (ug/L) 1.E+07 1.E+06 1.E+05 1.E+04 1.E+03 1.E+02 1.E+01 1.E+00 1E-07 1E-06 0.00001 0.0001 0.001 0.01 0.1 1 10 Filtered/Unfiltered Ratio 13

Site 1 (Alabama): Unfiltered Iron vs. Filtered/Unfiltered Ratio 1.E+07 Unfiltered Iron (ug/L) 1.E+06 1.E+05 1.E+04 1.E+03 1.E+02 1E-07 1E-06 0.00001 0.0001 0.001 0.01 0.1 1 10 Filtered/Unfiltered Ratio

14 Site 1 (Alabama): Chromium vs. Iron in Unfiltered Groundwater 10000 R2 = 0.99 Chromium (ug/L) 1000 100 10 1 0.1 1.E+01 1.E+02 1.E+03 1.E+04 Iron (ug/L) 1.E+05

1.E+06 1.E+07 Background Site 15 Site 1 (Alabama): Unfiltered Chromium vs. Filtered/Unfiltered Ratio Unfiltered Chromium (ug/L) 10,000 1,000 100 10 1 0.0001 0.001 0.01

0.1 1 10 Filtered/Unfiltered Ratio 16 Site 1 (Alabama): Vanadium vs. Iron in Unfiltered Groundwater 10000 R2 = 0.99 Vanadium (ug/L) 1000 100 10 1 0.1 1.E+01

1.E+02 1.E+03 1.E+04 Iron (ug/L) 1.E+05 1.E+06 1.E+07 Background Site 17 Site 1 (Alabama): Unfiltered Vanadium vs. Filtered/Unfiltered Ratio 10,000 Unfiltered Vanadium (ug/L) 1,000 100

10 1 0.0001 0.001 0.01 0.1 1 10 Filtered/Unfiltered Ratio 18 Site 2 (Georgia): Aluminum vs. Iron in Unfiltered Groundwater 10000 n = 352 pH: 4.3 to 8.4 Aluminum (mg/L) 1000

mean = 5.9 100 DO: 1.3 to 12.6 mg/L 10 mean = 8.4 mg/L 1 0.1 0.01 0.01 0.1 1 10 100 1000 10000 Iron (mg/L) 19

Site 3 (Alabama): Aluminum vs. Iron in Unfiltered Groundwater n = 30 (m = 300) 1,000,000 pH: 5.8 to 6.2 100,000 DO: 0.9 to 10.4 mg/L Aluminum (ug/L) 10,000 ORP: -210 to +82 mV 1,000 100 10 1 10 100

1,000 Iron (ug/L) 10,000 100,000 1,000,000 Background Site 20 Site 3 (Alabama): Mercury vs. Iron in Unfiltered Groundwater 100 Mercury (ug/L) 10 1 0.1 0.01 10

100 1,000 10,000 Iron (ug/L) 100,000 1,000,000 Background Site 21 Site 4 (Alabama): Aluminum vs. Iron in Unfiltered Groundwater 100,000 n = 43 (m = 300) pH: 5.0 to 12.7 10,000 Aluminum (ug/L) mean = 7.7

DO: 0.7 to 5.7 mg/L 1,000 mean = 3.0 mg/L ORP: -270 to +268 mV 100 mean = +104 10 10 100 1,000 Iron (ug/L) 10,000 100,000 Background mV Site

22 Site 4 (Alabama): Arsenic vs. Iron in Unfiltered Groundwater 10,000 Arsenic (ug/L) 1,000 100 10 1 10 100 1,000 Iron (ug/L) 10,000 100,000 Background Site

23 Site 5 (Virginia): Aluminum vs. Iron in Unfiltered Groundwater n = 407 (m = 11) 100,000 TDS: 153 to 25,800 mg/L 10,000 mean = 4,350 Aluminum (ug/L) 1,000 mg/L 100 pH: 4.9 to 10.6 mean = 7.0 10 DO: 0.1 to 13.6 mg/L 1 10

100 1,000 10,000 Iron (ug/L) 100,000 Site 1,000,000 Background mean = 5.1 mg/L ORP: -421 to +344 mV 24 24 Site 5 (Virginia): Unfiltered Aluminum vs. Filtered/Unfiltered Ratio 100,000 Unfiltered Aluminum (ug/L) 10,000

1,000 100 10 1 0.0001 0.001 0.01 0.1 Filtered/Unfiltered Ratio 1 Site 10 Background 25 Site 5 (Virginia): Unfiltered Iron vs. Filtered/Unfiltered Ratio 1,000,000

Unfiltered Iron (ug/L) 100,000 10,000 1,000 100 10 0.001 0.01 0.1 Filtered/Unfiltered Ratio 1 Site 10 Background 26 Site 5 (Virginia): Copper vs. Aluminum in Unfiltered Groundwater

1000 Copper (ug/L) 100 10 1 0.1 1 10 100 1,000 Aluminum (ug/L) 10,000 100,000 Site Background 27

Site 5 (Virginia): Unfiltered Copper vs. Filtered/Unfiltered Ratio Unfiltered Copper (ug/L) 1000 100 10 1 0.1 0.01 0.1 1 10 Filtered/Unfiltered Ratio 28 Conclusions

Geochemical evaluation is a cost-effective approach for determining if metals contamination of groundwater has occurred Uses existing data (requires Al, Fe, Mn analyses) Does not require a valid background data set Lowers the probability of a false-positive determination Identifies the mechanism(s) responsible for elevated metals concentrations Geochemical evaluation complements statistical site-to-background comparisons If an element in the site data set fails a statistical test, then a geochemical evaluation should be performed 29

Recently Viewed Presentations

  • LE JARDIN DES PLANTES-PARIS_1 (France)

    LE JARDIN DES PLANTES-PARIS_1 (France)

    Fondé en 1626 par deux médecins de Louis XIII, ce jardin botanique est ouvert au public en 1640 et se développe sous la direction de Buffon de 1739 à 1788.
  • The Gruffalo by Julia Donaldson

    The Gruffalo by Julia Donaldson

    Gruffalo "Amazing!" said the Gruffalo. Gruffalo And off he slid to his logpile house. Narrator "It's Snake," said the mouse. "Why, Snake, hello! Mouse They walked and walked till the Gruffalo said, "I hear a hiss in the leaves ahead."...
  • Organic Tobacco Production Overview - Nc State University

    Organic Tobacco Production Overview - Nc State University

    Bio-solids/Sewage Sludge. Non-organic seeds & transplants. Synthetic Chemicals. Ash from burning. Sodium Nitrate. Bulldog Soda. Material Consideration. Use only approved products. ... Organic Tobacco Production Overview Last modified by: Matthew Vann ...
  • A View of Life - PC\|MAC

    A View of Life - PC\|MAC

    Monocot vs. Dicots. What are monocot and dicots? 61) Monocotyledons . have one seed leaf or monocot. Monocots also have . 1 . food source called a cotyledon. 62) Dicotyledons. have two seed leaves or dicot. Dicots also have ....
  • Unit 1, Week 1

    Unit 1, Week 1

    When you are frustrated you are unhappy because you can't do or finish something. You might feel helpless, angry, or discouraged if you are frustrated about something. I get frustrated when I have to drive in traffic. 2. En español,...
  • 'Alternative' Conflict - Mrsjgibbs

    'Alternative' Conflict - Mrsjgibbs

    Poppies by Jane Weir Three days before Armistice Sunday and poppies had already been placed on individual war graves. Before you left, I pinned one onto your lapel, crimped petals, spasms of paper red, disrupting a blockade of yellow bias...
  • www.dps61.org

    www.dps61.org

    Mitosis. All daughter cells contain the same genetic information from the original parent cell from which it was copied. Every different type cell in your body contains the . same
  • City college Enrollment basics - City College of New York

    City college Enrollment basics - City College of New York

    City College understands that you are not an expert at being a college student, yet. To address that we have a number of people and offices whose job is to get you to the point of being an expert. ......