Source Identification for particle bound metals in the San Juan River

Transcription

1 Source Identification for particle bound metals in the San Juan River Logan Frederick, William Johnson, Diego Fernandez, Thure Cerling University of Utah, Geology and Geophysics

2 Mines in the area (Upper Animas Watershed) discharge an average of 5.4 million gallons per day. Volume of the release (from GKM spill) was later determined to be equivalent to four days of current acid mine drainage from this historical mining area. - EPA, Executive Summary (EPA, 2016a) Where are all the metals going?

3 Silverton Durango Mexican Hat Farmington

4 USGS Lake Cores Particle bound contaminants from San Juan River deposited in Lake Powell USGS collected a sediment core in San Juan arm of Lake Powell in 2010 Variation in elements and elemental ratios down core Indicating potentially unique inputs over time Goal: Differentiate sources of particle bound contaminants in deposited sediment of Lake Powell (Hornewer, N.J., 2014)

5 San Juan Watershed: First step: characterize tributaries of San Juan Watershed Drains ~24,600 mi 2 Snowmelt Monsoons 8 Main Tributaries: 1. Animas 2. Upper San Juan 3. La Plata 4. Chaco 5. Mancos 6. McElmo 7. Montezuma Creek 8. Chinle

6 USGS Stream Gauges }Snowmelt}Snowmelt Animas River Upper San Juan River La Plata River Mancos River McElmo Creek

7 Varying Geologic Sources Geology is source of particle bound metals Shale Sandstone Intrusive/Metamorphic Volcanic Sedimentary Alluvium/Water EX: Mancos Shale has Ba, Mn, V, and Zn (Sullivan et al., 2017)

8 11 sampling locations: Tributaries and main channel of San Juan synoptically sampled Total and Filtered (<0.45 µm) TSS Particle Size ICP-MS Lead Isotopes (pending)

9 Loads mmmm mmmmmmmmmm LL ww Discharge LL ww ffff 3 ffff3 ssssss = mmmm mmmmmmmmmm ssssss UT CO McElmo Mancos USGS station AZ San Juan Animas SJ La Plata SJ Mancos SJ McElmo SJ SJ NM upstream downstream

10 Potential signatures mmmm mmmmmmmmmm LL ww TSS LL ww mmmm pppppppppppppppppp = mmmm mmmmmmmmmm mmmm pppppppppppppppppp *Samples from EPA, UDEQ, CDPHE, NMED during GKM spill and year after

11 Pb-Isotopes Church et al., 1997 collected bed sediment Analyzed for lead-isotopes to fingerprint different sources of lead in basin Un-mineralized and mineralized rock have different Pb-isotope signatures Results: Cement creek and upper Animas River had signature of vein-type ore mineralization characteristic of Eureka graben Animas signature as low as Aztec was not strongly influenced by tributaries Mineral Creek Cement Creek Animas Figure 33 from Church et al., 1997

12 Future Work Goal: Differentiate sources (contributing tributaries) of particle bound contaminants in deposited sediment of Lake Powell Need to determine signatures for each tributary Elemental Ratios Isotopic Signatures Chinle Sampling Relate to 2011 sediment cores, 2015 sediment traps, 2017 sediment cores

13 References Church, S.E.; Kimball, B.A.; Fey, D.L.; Ferderer, D.A.; Yager, T.J.; Vaughn, R.B. Source, Transport, and Partitioning of Metals between Water, Colloids, and Bed Sediments of the Animas River, Colorado. U.S. Geological Survey Open-File Report Environmental Protection Agency (EPA) One Year After the Gold King Mine Incident: A Retrospective of EPA s Efforts to Restore and Protect Impacted Communities. August 1, Sullivan, Kate; Cyterski, Michael; Knightes, Chris; Kraemer, Stephen R.; Washington, John; Prieto, Lourdes; and Avant, Brian. Environmental Protection Agency (EPA) Analysis of the Transport and Fate of Metals Released from the Gold King Mine in the Animas and San Juan Rivers. January, Hornerwer, N.J Sediment and Water Chemistry of the San Juan River and Escalante River Deltas of Lake Powell, Utah, United States Geological Survey, Open-File Report

14 Gold King Spill Results: Total, dissolved, and TSS EPA, NMED, UDEQ, CDPHE Elements associated with particles (<0.45 µm) did not change with different discharge events GKM spill, monsoons, base flow and spring runoff Al, As, Be, Cd, Cr, Co, Cu, Fe, Pb, Mn, Ni, V, Zn No change in particle association among tributaries Animas SJ La Plata SJ Mancos SJ McElmo SJ SJ upstream downstream

15 Mass on particle TSS mmmm mmmmmmmmmm LL ww LL ww mmmm pppppppppppppppppp = mmmm mmmmmmmmmm mmmm pppppppppppppppppp Animas SJ La Plata SJ Mancos SJ McElmo SJ SJ upstream downstream

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17 Gold King Spill Results: Total, dissolved, and TSS EPA, NMED, UDEQ, CDPHE USGS stream gauges Discharge Events from 8/2015 to 10/ GKM Spill 2. Monsoon 3. Baseflow 4. Spring snow melt 5. Monsoon

18 Analyzed the labile (digestion 2M) components for the lead-isotopic composition of the samples to fingerprint different sources of lead within the basin and to quantify the relative contributions of metals from the different fluvial processes because the un-mineralized rocks and mineralized deposits have differing lead isotopic signatures. Stable Isotopes: Pb-206 U x 10 9 yr Pb-207 U x 10 8 yr Pb-208 Th x yr Pb-204 entirely primordial xx PPPP 204 PPPP Fixed Ratio as baseline to estimates amounts of radiogenic Pb present in rocks as a result of decay from U or Th "The fingerprinting of the different mineral deposit districts is possible because, at the time of the formation of the deposits the lead ratios was frozen into the deposits. In contrast, lead in the rocks within the Animas River watershed continues to change with time in direct proportion to the ratio of the parent isotopes to Pb (204). Lead is abundant in these mineral deposits."