Speciation and Isotopic Composition of Sulfide and Sulfate Minerals
Michele Tuttle, Paul Briggs, and Cyrus Berry
Eastern Kentucky New Albany Shale [Large version of shale outcrop photo]
Sulfur is ubiquitous in the natural geochemical environment. It occurs in sulfide and sulfate minerals, as well as in its elemental state, in ores related to mineral deposits; in thick beds of marine and terrestrial evaporites; in surface and ground water; in organosulfur compounds that comprise all living organisms, and in atmospheric aerosols. These sources are linked to the sulfur cycle through a number of geochemical processes. Understanding these processes, whether natural or anthropogenic, is often key to help unravel environmental issues such as acid-rock drainage, salinization of steams and rivers, attenuation of contaminant plumes in ground water, contamination related to combustion/refining of energy commodities, and climate change.
There are a number of geochemical static and kinetic tests used to understand the processes within a sulfur cycle, whether at a local research site or on a global scale. They include analyzing the amount, species and isotopic composition of sulfur in a snapshot or within a temporal framework. This subtask of the Aqueous Geochemistry Research and Development Project evaluates and develops methods needed to provide the data for the USGS studies that look at the processes within the entire sulfur cycle or in individual reservoirs.
Examples of recent USGS studies using methods developed in this subtask include predicting the acid-generating capacity of mining waste (fig. 1). Many of these predictions rely on analysis of sulfur in the landscape or in mine waste, yet there are many different forms of sulfur with different weathering characteristics and reactivity. Knowing what minerals are present and their relative reactivity is key to understanding acid-rock drainage and metal mobility that accompanies it. Using the isotopic composition of each individual mineral can be used to successfully track which minerals contribute most to the acid-mine drainage (Tuttle and others 2003c; Tuttle and others, 2003d).
Figure 1. Pictures of alteration scars, Questa, New Mexico (left) and acid-rock drainage in Red Well Creek, Colorado (right).
Photos by P. Briggs and M. Tuttle, respectively. [Large version of Figure 1 photo]
Another example is the weathering of black shale that results in acid generation, metal mobility, and salinization of ground and surface water (fig. 2). Better understanding of the forms of sulfur can lead to better remediation and reclamation decisions. In addition selective extractions of the shale and weathering products will help understand the residence of metals. Metal analyses of all solutions and isotopic compositions of separated sulfur phases help track the effectiveness of separating metal and sulfur phases that include sphalerite, chalcopyrite, clausthalite, pyrite, elemental sulfur, water-soluble sulfate salts (e.g. gypsum, melanterite, thenardite), alunite/jarosite, barite and iron oxides. Synthetic samples of similar compositions to those being studied and well-characterized field-collected samples are used in weathering simulation experiments to determine what processes control the redistribution and mobility of metals, acid, and constituents related to salt loading. These experiments also consider variables such as climate. The speciation, extraction and experimental results are then evaluated to develop working hypotheses about acid-generation, metal mobility, and salt loading (Tuttle and others, 2003b; Tuttle and Breit, 2004; Tuttle and others, 2005a,b).
Figure 2. Pictures of acid-generating, iron sulfate salts on the New Albany Shale, Kentucky (left) and sodium sulfate salts on the surface of soils derived from the Mancos Shale (right).
Photos by M. Tuttle and D. Murphy, respectively. [Large version of Figure 2 image]
The third example is the natural attenuation of organics in a landfill plume in an alluvial aquifer. In this study, it was critical to understand the natural sulfur-cycle processes in the uncontaminated portion of the aquifer before addressing the role of sulfate reduction in attenuating the organics in the leachate plume (Tuttle and others, 2003a; Breit and others, 2005) (fig. 3).
Figure 3. Photos of iron-monosulfide layers in surface layers of the alluvium at the Norman landfill site (left) and framboidal pyrite in the saturated zone.
Photos by M. Tuttle and G. Breit, respectively. [Large version of Figure 3 image]
Work in this subtask is currently supporting the following Mineral Resources Program projects:
- The Research Chemistry Core Support Project,
- Development of Geoenvironmental Models for Mineral Deposits Project,
- Geochemical and Isotopic Studies Project,
- Pathways of Metal Transfer from Mineralized Sources to Bio-receptors Project,
- Process Studies of Contaminants Associated with Mineral Deposits Project,
- Geochemical Landscapes Project,
- Mancos Shale Landscapes Project,
- Headwaters Province Project,
- USGS Venture Capital Project.
We have provided critical sulfur isotopic data to the Questa New Mexico/Red River Project to help assess the source of metal/sulfate contamination in a stream affected by acid-rock drainage. Sulfate in leachates from the Mancos Shale has lead to a collaborative relationship with scientists in Bureau of Reclamation who are interested in the natural availability of metals and salt that will be leached during irrigation of agricultural fields on the Mancos Shale and collaboration with the Bureau of Land Management to assess salt on the Gunnison Gorge National Conservation Area, Colorado. This joint effort provides data to help address issues of importance to the Colorado River Salinity Control Forum, Gunnison Basin Selenium Task Force, and the Grand Valley Selenium Task Force by providing isotopic tracer data that help linking salt and metal loads in the Upper Colorado River to weathering of major geologic units in the watershed.
Breit, G.N., Tuttle, M.L.W., Cozzarelli, I.M., Christenson, S.C., Jaeschke, J.B., Fey, D.L. and Berry, C.J., 2005, Results of chemical and sulfur isotopic analyses of sediment and water from Canadian River alluvium near a closed municipal landfill, Norman, Oklahoma: U.S. Geological Survey Open-file Report 2005-1091, 37 pp. Available online at: http://pubs.usgs.gov/of/2005/1091/.
Tuttle, M.L.W., and Breit, G.N., 2004, Metal mobility, transport, and fate during weathering of Devonian metalliferous black shale, in, Water-Rock Interaction 2004. Leiden, A. A. Balkema Publishers, p. 883-886.
Tuttle. M., Breit, G., Cozzarelli, I., and Christenson, S., 2003a Sulfur Geochemistry in an alluvial aquifer affected by landfill leachate—a case study from Norman, OK USA: Southcentral, Southeastern Section Geological Society of America 2003 Abstracts with Programs, v. 35, p. 73. Available online at: http://gsa.confex.com/gsa/2003SC/finalprogram/abstract_47720.htm.
Tuttle, M.L.W., Breit, G.N., Goldhaber, M.B., 2003b, Geochemical data from New Albany shale, Kentucky: a study in metal mobility during weathering of black shales: U.S. Geological Survey Open-file Report 03-207, 57 pp. Available online at: http://pubs.usgs.gov/of/2003/ofr-03-207/.
Tuttle, M.L.W., Briggs, P.H., and Berry, C.J., 2003c, A method to separate phases of sulfur in mine-waste piles and natural alteration zones,
and to use sulfur isotopic compositions to investigate release of metals and acidity to the environment, in Proceedings of the Sixth International Conference
on Acid Rock Drainage (ICARD 6),
Cairns, North Queensland, Australia, July 14-17, 2003, p. 1141-1145.
Abstract available on-line at: http://www.shop.ausimm.com.au/paperdetails.php?PaperID=822.
PDF file of publication [200 KB].
Tuttle, M.L.W., Fahy, J., Grauch, R.I., Ball, B.A., Chong, G.W., Elliott, J.G., Kosovich, J.J., Livo, K.E., and Stillings, L.L., 2007, Results of chemical analyses of soil, shale, and soil/shale extract from the Mancos Shale Formation in the Gunnison Gorge National Conservation Area, Southwestern Colorado, and at Hanksville, Utah: U.S. Geological Survey Open-File Report 2007-1002D, 269 p. Available online at: http://pubs.usgs.gov/of/2007/1002/D/.
Tuttle, M.L.W., Fahy, J.W., Grauch, R.I., and Stillings, L.L., 2005, Salt and selenium in Mancos shale terrane on the Gunnison Gorge National Conservation Area, western Colorado, USA [abs.]: Geological Society of America Rocky Mountain Section 57th Annual Meeting, May 23-25, 2005: Abstracts with Programs, v. 37, no. 6, p. 45. (Abstract and presentation) Available online at: http://gsa.confex.com/gsa/2005RM/finalprogram/abstract_86998.htm.
Tuttle M.L.W., Fahy, J.W., Grauch, R.I., and Stillings, L.L., 2005a, Salt and selenium from Mancos Shale, Uncompahgre River Basin, Southwestern Colorado, USA, in Proceedings of the International Salinity Forum—Managing Saline Soils and Water: Science, Technology, and Social Issues, Riverside, California, April 25-27, 2005, p. 457-460.
Tuttle, M.L.W., Wanty, R.B., and Berger, B.R., 2003d, Environmental controls on water quality: case studies from Battle Mountain Mining District, North-central Nevada: U.S. Geological Survey Bulletin 2210-A, 30 p. Available online at: http://pubs.usgs.gov/bul/b2210-a/.
Box 25046 MS 964D Denver Federal Center
Denver, CO 80225-0046
Phone: (303) 236-1944