Jonathan J. Kolak

Anthropogenic inventories and historical and present accumulation rates of copper in Great Lakes sediments

Abstract Sediment cores were collected from depositional basins in lakes Michigan, Ontario and Superior to assess spatial and temporal variations in Cu accumulation rates and inventories. Sediment chronologies were determined via 210 Pb dating, and 210 Pb inventories were used to correct for the effects of sediment focusing. Among the lakes studied, Cu loading histories generally decrease to the present, signifying a regional reduction in the anthropogenic release of Cu to the environment. Focusing-corrected Cu accumulation rates in surficial sediments vary significantly within lakes Michigan and Ontario, suggesting that recent inputs of Cu to these 2 lakes may have been dominated by localized sources. Variations in Cu accumulation rates within Lake Superior are interpreted to be insignificant, suggesting either that Lake Superior is well-mixed with respect to copper inputs or that the lake is dominated by a single source for Cu. Recent measurements of atmospheric fluxes of Cu within the Great Lakes region generally indicate that the atmosphere accounts for less than 50% of the Cu accumulating in surficial sediments. Historical Cu accumulation rates from Lake Superior are poorly correlated with Cu production associated with local smelters, but favorably agree with national production rates. Trends in historical Cu accumulation rates within all 3 lakes may indicate that recent declines in Cu loading can be attributed to the enactment of stricter environmental regulations as well as changes in the use of Cu. Focusing-corrected Cu inventories in lakes Michigan, Ontario, and Superior are generally invariant within a given lake, indicating that, historically, these lakes have been dominated either by a single source or were well-mixed with respect to Cu inputs. The disparity between the results from recent accumulation rates and historical inventories may reflect differences in how the Great Lakes respond to contaminant loading on short (e.g. years) versus long (e.g. decades) timescales.

Ground-water, large-lake interactions in Saginaw Bay, Lake Huron: A geochemical and isotopic approach

Delineating the nature and extent of ground-water inputs is necessary to understand the hydrochemistry of large lakes. Characterizing the interaction between ground water and large lakes (e.g., the Great Lakes) is facilitated by the use of geochemical and isotopic data. In this study, pore waters were extracted from sediment cores collected from Saginaw Bay and the surrounding Saginaw lowland area; the geochemistry and stable isotope signature of these pore waters were used to identify sources for the water and solutes. Cores from Saginaw Bay and the Saginaw lowland area yielded strong vertical gradients in chloride concentrations, suggesting that a high-chloride source is present at depth. The spatial distribution of cores with elevated chloride concentrations corresponds to the regional distribution of chloride in ground water. Most of the Saginaw lowland area cores contain water with significantly lower δ 18 O values than modern meteoric water, suggesting that the water had been recharged during a much cooler climate. The δ 18 O values measured in pore waters (from Saginaw Bay cores) containing high chloride concentrations are similar to modern meteoric water; however, values lighter than modern meteoric water are encountered at depth. Chloride:bromide ratios, used to distinguish between different chloride sources, identify formation brine as the likely source for chloride. Transport models indicate that a combination of advection and diffusion is responsible for the observed Saginaw lowland area pore-water profiles. Pore-water profiles in Saginaw Bay sediments are produced primarily by diffusion and require significantly less time to evolve. An upward flux of solutes derived from formation brine could occur elsewhere within the Great Lakes region and significantly affect the geochemical cycling of chloride and other contaminants (e.g., trace metals).

Nearshore versus offshore copper loading in Lake Superior sediments: Implications for transport and cycling

Abstract A thorough understanding of the fate and transport of metals in Lake Superior is necessary in order to predict the ability of Lake Superior to recover from anthropogenic perturbations (copper mining). Sediment cores were collected from nearshore and offshore sites in Lake Superior and used to evaluate spatial and temporal variations in copper loading associated with mining-related activities. Although both settings have been strongly affected by anthropogenic releases of copper, copper concentrations in nearshore cores are significantly greater than those found in offshore cores, implying that nearshore copper loading is dominated by simple deposition and burial of sediment generated from mining activities. Temporal variations in copper profiles in sediments from nearshore environments closelymimic copper production rates. Conversely, copper loading histories derived from offshore sediments are not well correlated to production rates. The offshore sediment cores, when compared with analogous cores from Lakes Ontario and Michigan, show that the average, lake-wide intensity of copper loading in Lake Superior is comparable to the other two lakes, despite the fact that Lake Superior has received the largest total burden of anthropogenic copper. Cu/Zn ratios, used to evaluate the amount of copper loading derived from mining discharges, vary strongly in nearshore environments in response to loading. Cu/Zn ratios in offshore sediments are much less variable, implying that copper loading may be regulated by additional mechanisms (solution chemistry and/or biologic uptake). Study of trace metal partitioning within Lake Superior sediments indicates that the organic fraction of the sediment contains the majority of the copper. Copper concentrations in offshore sediments are significantly correlated to organic carbon content of the sediment whereas copper concentrations in nearshore sediments are not. These findings support the model that transport and deposition of particles released from mining discharges dominate copper loading in nearshore sediments, whereas biologic uptake and settling of particulate organic matter may regulate copper loading in offshore sediments.

- The effect of coal rank on the physicochemical interactions between coal and CO 2 -implications for CO 2 storage in coal beds

Publisher Summary This chapter explores the interactions between gaseous and supercritical carbon dioxide (CO2) with coal, which were examined on 8 samples ranging in rank from lignite through anthracite. Gas sorption isotherms were measured on moisture-equilibrated, ground coal samples. Carbon dioxide sorption capacities measured on moisture-equilibrated coal samples were positively correlated with fixed carbon content. The other major constituents including coal-mineral matter, bitumen, and water exhibited little or no relation with CO2 sorption capacity. Supercritical CO2 injected into coal beds may mobilize aliphatic hydrocarbons and PAHs. The lack of discernible influence of bitumen content on either gas sorption or hydrocarbon mobilization may be an artifact of the procedure used to determine bitumen content. These preliminary findings indicate that the fixed carbon content of coal, on an eqm or as-received basis, may be a useful parameter in developing a framework to assess CO2 storage capacity and the environmental ramifications associated with storing CO2 in coal beds.

Petrographic and Vitrinite Reflectance Analyses of a Suite of High Volatile Bituminous Coal Samples from the United States and Venezuela

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted material contained within this report. Introduction This report presents vitrinite reflectance and detailed organic composition data for nine high volatile bituminous coal samples. These samples were selected to provide a single, internally consistent set of reflectance and composition analyses to facilitate the study of linkages among coal composition, bitumen generation during thermal maturation, and geochemical characteristics of generated hydrocarbons. Understanding these linkages is important for addressing several issues, including: the role of coal as a source rock within a petroleum system, the potential for conversion of coal resources to liquid hydrocarbon fuels, and the interactions between coal and carbon dioxide during enhanced coalbed methane recovery and(or) carbon dioxide sequestration in coal beds. Several recent studies have utilized detailed information on coal maceral composition to refine the understanding of these The nine isorank samples characterized in this study differ in geographic location, timing of deposition, and organic matter composition. Five Pennsylvanian coal samples from the Illinois, Appalachian, and Black Warrior basins, USA, two Paleocene and one Eocene-Oligocene coal samples from the Maracaibo basin, Venezuela, and one Eocene coal sample from the Gulf of Mexico Coastal Plain, USA, comprise the sample set (Table 1; fig. 1). All original petrographic data for the samples are included in the Appendix to this report. Results from proximate-ultimate analyses are given in earlier publications Mine channel samples of the three Venezuelan coals, the Santo Tomas coal (Gulf of Mexico basin, USA), and the Indiana, Ohio, and Alabama coals were collected according to American Society for Testing and Materials (ASTM) D 4596: Practice for collection of channel samples in a mine (ASTM, 2007). The Cedar Grove sample from West Virginia was collected from core according to ASTM D 5192: Practice for collection of coal samples from core (ASTM, 2007). Sample Preparation Samples were prepared for analysis according to ASTM D 2797: Preparing coal samples for microscopical analysis by reflected light (ASTM, 2007). Samples were ground to pass a 850-μm (No. 20 mesh) sieve and mounted in 1-inch molds using a heat-setting thermoplastic powder or epoxy resin medium. Two mounts were made for each sample. Examination surfaces were ground and polished, then desiccated overnight prior …