Oxidation and mobilization of naturally O id i d bili i f ll occurring chromium in soils of the Sacramento Valley, California Chris Mills, Jean Morrison, Martin Goldhaber Chris Mills, Jean Morrison, Martin Goldhaber U.S. Department of the Interior U.S. Department of the Interior U.S. Geological Survey U.S. Geological Survey (cmills@usgs.gov) (cmills@usgs.gov) ( ( @ @ g g g g ) )
Outline • Chromium toxicity and sources Chromium toxicity and sources – – importance of speciation importance of speciation • Naturally occurring Cr(VI) in groundwater Naturally occurring Cr(VI) in groundwater – – a global issue a global issue • Natural Cr distribution in Sacramento Valley soils N N Natural Cr distribution in Sacramento Valley soils l C di l C di ib i ib i i S i S V ll V ll il il • Cr(VI) in vadose zone soils and sediments Cr(VI) in vadose zone soils and sediments • Natural Cr(VI) generation in soils Natural Cr(VI) generation in soils • Oxidation reactivity of natural versus fertilizer • Oxidation reactivity of natural versus fertilizer Oxidation reactivity of natural versus fertilizer derived Cr(III) Oxidation reactivity of natural versus fertilizer-derived Cr(III) derived Cr(III) derived Cr(III)
Toxicity and carcinogenesis of chromium C (VI) (HC O - ) - ) C (VI) (HC O Cr(VI) (HCrO Cr(VI) (HCrO 4 anion transporter anion transporter cation cation - ion - ion Cr(VI) Cr(VI) ( ( ) ) Oxidative Oxidative Oxidative Oxidative Detoxific Detoxific Reduct Reduct DNA DNA breakage breakage Cr(V) Cr(V) Reduction by Reduction by Reduction by Reduction by D DNA adducts DNA adducts Vitamin C Vitamin C Cr(IV) Cr(IV) ligand ligand Cr Cr Cr(III) Cr(III) Cr(III) Cr(III) National Toxicology Program National Toxicology Program Salnikow & Zhitkovich, 2008, Chem. Res. Toxicol. Salnikow & Zhitkovich, 2008, Chem. Res. Toxicol.
Sources of chromium in soil and water • Anthropogenic Anthropogenic – Industrial waste Industrial waste – – often often Cr(VI) Cr(VI) • Primary contaminant at over ½ Primary contaminant at over ½ a y co a y co a a a a a o e ½ a o e ½ of Superfund sites of Superfund sites • Tanneries Tanneries Leather Tanning Leather Tanning – – Morocco Morocco • Corrosion inhibitors Corrosion inhibitors Trace Metal Concentrations in Rock • Metal plating Metal plating Phosphates (mg/kg) • Wood Preservatives Wood Preservatives Cr Ni As – Fertilizers Fertilizers – – Cr(III) Cr(III) ( ( ) ) 1 - 331 1 - 125 1-21 • Inorganic Inorganic • Biosolids Biosolids EPA 747-R-98-003 (1999) • Natural • Natural Natural Natural – – Cr(III) Cr(III) Cr(III) Cr(III) – Ultramafic Rocks Ultramafic Rocks Chromite Chromite (FeCr (FeCr 2 O 4 ) Pellerin & Booker (2000) Pellerin & Booker (2000) Environmental Health Perspectives Environmental Health Perspectives
Naturally occurring Cr(VI) in the news “Many cities in California have chromium 6 in their water at higher levels Many cities in California have chromium 6 in their water at higher levels than Beachwood, says lawyer Stephen Lewis, who represents the plant's former owners. He argues that the chromium 6 in Beachwood's water could be naturally present or the result of activity unrelated to the plant.” y p y p –San Francisco Chronicle, 12-14-08 “Hexavalent chromium is not naturally occurring; though industry y g; g y lobbyists and their PR machines have done a great job making you believe it does. Hexavalent chromium is pollution;…” –Erin Brockovich, 2-15-2011, comment on CA Proposed Public Health Goal for Cr(VI) in drinking water (0.02 mg L -1 ) “The Cr (VI) you identified in Honolulu’s water supply as is probably the case for The Cr (VI) you identified in Honolulu s water supply, as is probably the case for every other city you tested, is not industrial “pollution” — it’s Mother Nature.” –Roger Brewer, Ph.D., 6-7-2011, letter to the Editor in response to EWG report on Cr(VI) in municipal drinking water, Norman (OK) Transcript Cr(VI) in municipal drinking water, Norman (OK) Transcript
Naturally occurring Cr(VI) in groundwater–global distribution World Health Organization g MCL = 50 g L -1 La Spezia, Italy La Spezia, Italy 73 g L 73 73 73 g L -1 L 1 Fantoni et al. (2002) Fantoni et al. (2002) Env. Geol. Env. Geol. United Arab Emirates 400+ g L -1 Wood et al. (2009) Ground Water Mojave Desert , CA Mojave Desert Mojave Desert , CA Mojave Desert CA CA 60 60 g L g L -1 1 Izbicki et al. (2008) Appl. Geochem. Izbicki et al. (2008) Appl. Geochem. Yil Yilgarn Craton C t 430 g L -1 Gray (2003) Geochem. Explor. Environ. Anal. Environ. Anal. Oze et al., 2007, PNAS
Cr concentrations northern California surface soils are extremely high y g Krevor et al., 2009, Energy Procedia North American Soil Geochemical S G Landscapes project, USGS
Regional-scale soil geochemistry of northern California
Regional-scale soil geochemistry of northern California Morrison et al., 2009, Appl. Geochem. Morrison et al., 2009, Appl. Geochem.
Rock and surface soil total Cr concentrations 100000 100000 Sacram Riv 10000 10000 ver mento mg/kg) 1000 Cr (m EPA screening level 100 mean U.S. U S soil conc. 10 Soil Rock Soil Rock Rock Rock Soil Soil Soil Soil Soil Soil Soil S il Rock R k Serpentine Serpentine Great Valley Valley West East Morrison et al., 2009, Appl. Geochem. Morrison et al., 2009, Appl. Geochem.
Contributions of source materials to western valley soils Great Valley 0 1 Sequence Rocks and Soils Rocks and Soils 0.2 0.8 Li 0.4 0.6 Cr r x10 UM Rocks 0.6 0.4 and Soils and Soils 0.8 0.2 1 0 0 0.2 0.4 0.6 0.8 1 Ti/10 Ti/10 Morrison et al., 2009, Appl. Geochem. Morrison et al., 2009, Appl. Geochem.
Cr(VI) in valley groundwater is a health concern CA Public Health Goal = 0.02 μ g L μ g L -1 1 CA MCL = 50 μ g L -1 CA MCL = 50 μ g L 1 CA Public Health Goal = 0.02 Sacramento Sacramento Davis Davis Davis Davis M Morrison et al., 2009, Appl. Geochem. Morrison et al., 2009, Appl. Geochem. M i i t t l l 2009 A 2009 A l G l G h h Wanty et al., 2009, Appl. Geochem. Wanty et al., 2009, Appl. Geochem. Dawson et al., 2008, USGS Data Series Dawson et al., 2008, USGS Data Series
Cr(VI) in valley groundwater is a health concern CA Public Health Goal = 0.06 μ g L μ g L- -1 1 CA MCL = 50 μ g L CA MCL = 50 μ g L -1 1 CA Public Health Goal = 0.06 80 70 ) 60 60 VI)] ( g L -1 50 Sacramento Sacramento 40 Davis Davis Davis Davis [Cr(V 30 20 10 0 0 2 4 6 8 10 12 14 16 18 20 [NO 3- ] (mg N L -1 ) Morrison et al., 2009, Appl. Geochem. Morrison et al., 2009, Appl. Geochem. M M i i t t l l 2009 A 2009 A l G l G h h Wanty et al., 2009, Appl. Geochem. Wanty et al., 2009, Appl. Geochem. Dawson et al., 2008, USGS Data Series Dawson et al., 2008, USGS Data Series
Cr(VI) increases with depth in shallow soils 0 1 1 (meters) (meters) 2 Depth Depth 3 4 4 0 5 10 15 0 5 10 15 0 5 10 15 0 5 10 15 0 5 10 15 0 5 10 15 Cr(VI) ( g kg Cr(VI) ( g kg -1 1 ) Mills et al., 2011, Appl. Geochem.
Cr(VI) is elevated in deeper soils/sediments 0 5 h (meters) h (meters) 10 15 Depth Depth 20 25 30 0 25 50 0 25 50 0 25 50 0 25 50 0 25 50 0 25 50 Cr(VI) ( g kg Cr(VI) ( g kg -1 1 ) Mills et al., 2011, Appl. Geochem.
Chromium cycling in natural environments Mn Oxides Mn Oxides dissolution dissolution dissolution dissolution Chromite Chromite Cr(III) Cr(III) (FeCr 2 O 4 ) (FeCr Cr(VI) Cr(VI) Cr(VI) Cr(VI) e.g. Cr(OH) 3 , CrOH e.g. Cr(OH) , CrOH 2+ 2+ e.g. HCrO 4 e.g. HCrO - , CrO , CrO 4 2- - di di dissolution/ dissolution/ l ti l ti / / Fe 2+ precipitation precipitation sorption sorption Organic Carbon Sulfides Sulfides e.g. e.g. Cr(OH) Cr(OH) 3 (s) (s) clays and clays and oxides oxides
Mn oxides are abundant in valley soils 5 mm 2500 Total Total Mn Mn Mn Mn 2000 soil g per kg 1500 Hydroxylamine- Hydroxylamine - reducible Mn reducible Mn mg 1000 500 500 Geometric Mean for Total Mn in U.S. surface soils Geometric Mean for Total Mn in U.S. surface soils (Shacklette and Boerngen, 1984) (Shacklette and Boerngen, 1984) 0 Mills et al., 2011, Appl. Geochem.
Soil pH is a major control on Cr cycling 1.2 Common pH Values of Common pH Values of 1.0 Sacramento Valley Soils Sacramento Valley Soils 0.8 HCrO HCrO 4 - 0.6 V) CrO 4 CrO CrO CrO 2- 2 Eh (V 0.4 0 4 Cr 3+ Cr 3+ 0.2 Cr(OH) Cr(OH) 2+ 2+ 0.0 0 0 Cr(OH) Cr(OH) 3 -0.2 -0.4 0 4 Cr(OH) 2 Cr(OH) + -0.6 2 3 4 5 6 7 8 9 10 11 pH
Several distinct residences of Cr in valley soils 50 m Smectite/Illite Smectite/Illite (~300 ppm Cr) (~300 ppm Cr) 0.5 m 0.5 m Chromite Chromite (FeCr (FeCr 2 O 4 ) Nano Nano- -crystalline crystalline Iron oxides Iron oxides (300 (300-500 ppm Cr) (300 (300-500 ppm Cr) 500 ppm Cr) 500 ppm Cr) Morrison, 2010, Ph.D. Thesis – Colorado School of Mines
Concentrations of different Cr residences vary widely Cr(VI) Cr(III) Cr oxidation capacity 10000 1000 r kg soil 100 orate stion 10 te cid diges Citrat mg per - metab 1 0.1 4-ac 0.01 0 01 Li 0.001 0 0001 0.0001 Mills et al., 2011, Appl. Geochem.
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