Natalie A. Kruse

Alkalinity production as an indicator of failure in steel slag leach beds treating acid mine drainage

Acid mine drainage is a serious environmental problem throughout mining regions of the US and around the world. In Appalachia, reuse of steel slag from steel production as a source of alkalinity for treatment of acid mine drainage has become a common practice. In these systems, dubbed steel slag leach beds, relatively clean surface water is percolated through a bed of steel slag to add large amounts of alkalinity to the water before mixing it with acidic, metalliferous mine water. These beds do not operate consistently and their failure mechanisms are poorly understood. Using the experience of Raccoon Creek watershed in southern Ohio, the alkalinity distribution of the discharge of six steel slag leach beds is compared. Two of these beds are still functional, one has been abandoned and three are operating poorly. The difference in alkalinity distribution between these beds suggests that a carbonate-dominated alkalinity system is an indicator of a poorly performing steel slag leach bed, while a more even distribution between hydroxide, carbonate and bicarbonate may point to more ideal operating conditions. In eight laboratory column experiments, this evidence was then expanded upon by testing different mixed media substrates (differing mixes of steel slag, wood chips and river gravel) to see which provided the most ideal alkalinity distributions. The columns that had steel slag mixed either with wood chips or wood chips and river gravel outperformed the column with slag only in terms of alkalinity distribution, perhaps due to microbial processes or increased hydraulic conductivity without significant added calcium or carbon that could drive calcium carbonate precipitation within the beds and causing them to fail.

Closing the loop: integrative systems management of waste in food, energy, and water systems

Modern food, energy, and water (FEW) systems are the product of technologies, techniques, and policies developed to address the needs of a given sector (e.g., energy or agriculture). Wastes from each sector are typically managed separately, and the production systems underlying FEW have traditionally treated pollution and waste as externalities simply diffused into the ambient environment. Integrative management that optimizes resource use presents opportunities for improving the efficiency of FEW systems. This paper explains how FEW systems can be optimized to (1) repurpose or cycle waste products, (2) internalize traditional externalities, and (3) integrate wastes with resource inputs across systems by diverting waste by-products from one system to meet demands of another. It identifies the means for “closing the loop” in production systems. Examples include management of legacy wastes from fossil fuel industries (coal and natural gas) and integrative designs for advanced renewable systems (biogas from waste, bioenergy from CAM plants, and solar). It concludes with a discussion of how studying the governance of such systems can assist in tackling interconnected problems present in FEW systems. New governance arrangements are needed to develop solutions that can align with regulatory frameworks, economics incentive, and policies. Four aspects of governances (property rights, policy design, financing, and scale) emerge as tools to facilitate improved institutional design that stimulates integrative management, technology innovation and deployment, and community development. The conclusion offers a framework through which integrative management of FEW systems can be linked to value chains in closed-loop systems.

Field Analysis of Polychlorinated Biphenyls (PCBs) in Soil Using Solid-Phase Microextraction (SPME) and a Portable Gas Chromatography-Mass Spectrometry System.

An expedited field analysis method was developed for the determination of polychlorinated biphenyls (PCBs) in soil matrices using a portable gas chromatography–mass spectrometry (GC-MS) instrument. Soil samples of approximately 0.5 g were measured with a portable scale and PCBs were extracted by headspace solid-phase microextraction (SPME) with a 100 µm polydimethylsiloxane (PDMS) fiber. Two milliliters of 0.2 M potassium permanganate and 0.5 mL of 6 M sulfuric acid solution were added to the soil matrices to facilitate the extraction of PCBs. The extraction was performed for 30 min at 100 ℃ in a portable heating block that was powered by a portable generator. The portable GC-MS instrument took less than 6 min per analysis and ran off an internal battery and helium cylinder. Six commercial PCB mixtures, Aroclor 1016, 1221, 1232, 1242, 1248, 1254, and 1260, could be classified based on the GC chromatograms and mass spectra. The detection limit of this method for Aroclor 1260 in soil matrices is approximately 10 ppm, which is sufficient for guiding remediation efforts in contaminated sites. This method was applicable to the on-site analysis of PCBs with a total analysis time of 37 min per sample. However, the total analysis time could be improved to less than 7 min per sample by conducting the rate-limiting extraction step for different samples in parallel.

Characterization and fate of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in soils and sediments at the Portsmouth Gaseous Diffusion Plant, Ohio

The U.S. Department of Energy Portsmouth Gaseous Diffusion Plant is in the early stages of decommissioning and decontamination. During operations, the site drew a large amount of electric power and had multiple large switchyards on site. These are a source of polychlorinated biphenyls (PCB) contamination to both on-site and off-site streams. Some soil remediation has been completed in the main switchyard. During 2011 and 2012, fifteen sites were sampled at the surface (<10 cm) and subsurface (20-30 cm) to characterize the extent of PCB contamination, to identify weathering and migration of PCB contamination and to explore potential polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) contamination due to transformer fires and explosions in the 1950s and 1960s. Stagnant sites tended to exhibit more migration of contamination to deeper sediments than sites with fast-moving waters, and the highest concentrations were found at the bottom of a settling pond. A signature set of five dioxin-like PCBs were consistently found across the site with higher concentrations in carbon rich surface sediments. PCB concentrations had a significant inverse correlation with clay content, suggesting that PCBs did not bind to clays at this site. Remediation has reduced PCB concentrations throughout the site compared to levels found in previous studies and long-term upkeep of sediment lagoons is necessary to retain PCB and dioxin-rich sediments. The flow regimen, organic carbon and clay content play a very important role in the fate of PCBs in the environment at the surface as well as downward migration.

Determination of Aroclor 1260 in soil samples by gas chromatography with mass spectrometry and solid-phase microextraction

A novel fast screening method was developed for the determination of polychlorinated biphenyls that are constituents of the commercial mixture, Aroclor 1260, in soil matrices by gas chromatography with mass spectrometry combined with solid-phase microextraction. Nonequilibrium headspace solid-phase microextraction with a 100 μm polydimethylsiloxane fiber was used to extract polychlorinated biphenyls from 0.5 g of soil matrix. The use of 2 mL of saturated potassium dichromate in 6 M sulfuric acid solution improved the reproducibility of the extractions and the mass transfer of the polychlorinated biphenyls from the soil matrix to the microextraction fiber via the headspace. The extraction time was 30 min at 100°C. The percent recoveries, which were evaluated using an Aroclor 1260 standard and liquid injection, were within the range of 54.9-65.7%. Two-way extracted ion chromatogram data were used to construct calibration curves. The relative error was <±15% and the relative standard deviation was <15%, which are respective measures of the accuracy and precision. The method was validated with certified soil samples and the predicted concentrations for Aroclor 1260 agreed with the certified values. The method was demonstrated to be linear from 10 to 1000 ng/g for Aroclor 1260 in dry soil.

Carbon Dioxide Dynamics and Sequestration in Mine Water and Waste

AbstractThe role and importance of CO2 in the mining sector has been overlooked until relatively recently. This review presents the complexities of CO2 and mine water evolution . Carbon sequestration using mine waters and solid wastes and recent research on the profound impacts of dissolved CO2 on active and passive treatment were reviewed. The literature indicates great promise for more efficient and fiscally competitive operations, lower environmental impacts, and a decreased carbon footprint for such operations. However, a tremendous amount of research and field testing is necessary to move many of these approaches forward to full scale common application.ZusammenfassungDie Rolle und Bedeutung von CO2 im Bergbausektor wurde bis vor kurzem nicht hinreichend berücksichtigt. Der folgende Überblick stellt die Komplexität des Systems CO2 und Grubenwassers dar. Die Kohlenstoffbindung mit Grubenwasser und festen Abfällen sowie die jüngsten Forschungen über die tiefgreifenden Auswirkungen von gelöstem CO2 über aktive und passive Behandlung wurden geprüft. Aus den Angaben in der Literatur ergeben sich große Erwartungen an die Effizienz und Wirtschaftlichkeit sowie geringe Umweltauswirkungen (bessere CO2-Bilanz) bei solchen Verfahren. Allerdings sind noch umfangreiche Forschungen und Feldversuche erforderlich, um die zahlreichen Ansätze in die Praxistauglichkeit zu überführen.ResumenEl rol y la importancia de CO2 en el sector minero han sido desestimadas hasta tiempos recientes. Esta recopilación crítica presenta las complejidades de la interacción entre CO2 y agua de minas. Se recopiló la información sobre la captura de carbono usando aguas y residuos sólidos de minas y sobre las investigaciones recientes acerca del impacto profundo de CO2 disuelto sobre los tratamientos pasivos y actives. La bibliografía sugiere amplias posibilidades para desarrollar operaciones más eficientes y más competitivas, con menores impactos ambientales y menores huellas de carbono. Sin embargo, una cantidad muy grande de investigación y de testeo en campo es aún necesaria para llevar muchas de estas aproximaciones hacia una aplicación a gran escala.摘要近几年,二氧化碳在采矿领域中的地位和作用引起广泛关注。文章介绍了二氧化碳在矿井水领域的复杂反应动力学机理及演化过程,综述了利用矿井废水及固体废弃物进行CO2捕集的研究现状,评价了溶解二氧化碳对于矿井废水主动处理与被动力处理的影响。该类技术具有经济、有效、低环境影响和碳占用少的巨大潜力。目前,还需要大量深入研究及野外试验才能使该技术成为现实。

Carbon Footprint Analysis of Source Water for Hydraulic Fracturing: A Case Study of Mine Water Versus Freshwater

In the face of climate change, less carbon intensive fuels are being sought. Natural gas has been perceived as a transition fuel, producing less CO2 when burned than coal, but it is not a renewable resource. Hydrocarbon-rich shale formations contain natural gas, natural gas condensate, and oil production potential, and the extraction of these compounds has allowed the USA to become one of the largest global producers of natural gas. Horizontal drilling and hydraulic fracturing are used to extract the shale gas, but hydraulic fracturing of one well typically requires between 7 and 19 million L of water. One option being explored is the use of treated mine water as an alternative to freshwater. The Marcellus and Utica shale formations underlie much of the eastern USA, and the Utica Shale is being pursued for its high natural gas potential in eastern Ohio. Permits for wells are being approved, but concerns about the water source for hydraulic fracturing fluid are increasing. We analyzed the carbon footprints of three different water sources: treated mine water from Corning, Ohio, freshwater from the Ohio River, and freshwater from Seneca Lake near the well site. CO2 emissions for each source were calculated during pumping, transportation, and treatment of the water for a one-time well use and annual use. The primary productivity increase that occurred after removal of mine discharge or reduction due to extraction from freshwater sources was also calculated. Annually, using treated mine water would emit 110,000 t of CO2-e (CO2 equivalent) if trucked to a treatment plant or 90,000 t of CO2-e if treated on-site, while using water from the Ohio River would emit 2,000 t of CO2-e, and using water from Seneca Lake would emit 4,500 t of CO2-e, annually. Of course, decreasing the amount of unpolluted freshwater used has other environmental benefits.ZusammenfassungIm Angesicht des Klimawandels werden Brennstoffe geringerer Kohlenstoffintensität gesucht. Erdgas wurde als Übergangsbrennstoff wahrgenommen, weil es weniger CO2 produziert als Kohle, aber es ist keine erneuerbare Ressource. Kohlenwasserstoffreiche Tonsteinformationen enthalten Erdgas, Erdgaskondensate und das Potential, Erdöl zu produzieren. Die Extraktion dieser Stoffe hat es erlaubt, daß die USA zu einem der größten globalen Produzenten von Erdgas wurde. Horizontalbohrungen und hydraulisches Fracken werden zur Förderung von Schiefergas genutzt, aber hydraulisches Fracken einer Bohrung benötigt typischerweise zwischen 7 und 19 Millionen L Wasser. Eine untersuchte Option ist die Verwendung von behandeltem Bergbauwasser als eine Alternative zu Süßwasser. Die Marcellus und Utica Tonformationen unterlagern weite Teile der östlichen USA,und der Utica Tonstein wird im östlichen Ohio wegen seines hohen Erdgaspotentiales aufgesucht. Bewilligungen für Bohrungen werden erteilt, aber Sorgen über die Herkunft des Wassers für das hydraulische Frackfluid nehmen zu. Wir haben den CO2-Fußabdruck von drei unterschiedlichen Wasserquellen untersucht: behandeltes Bergbauwasser von Corning, Ohio, Süßwasser aus dem Ohio Fluß, und Süßwasser aus dem Seneca See in der Nähe des Bohrplatzes. CO2-Emissionen für jede Quelle wurden für das Pumpen, den Transport und für die Wasseraufbereitung für den Fall einer einmaligen Nutzung oder einer mehrfachen Verwendung über ein Jahr berechnet. Die Zunahme primärer Produktivität, welche durch die Beseitigung des Bergbauwasseraustrittes entstand oder die Reduktion infolge der Entnahme aus Süßwasserquellen wurde ebenfalls berechnet. Für den Fall des Lastwagentransportes zu einer Wasseraufbereitung würde die Verwendung behandelten Bergbauwassers eine jährliche Emission von 110.000 t CO2-e (CO2-Äquivalent) bewirken, bei einer Behandlung vor Ort jedoch nur 90.000 t CO2-e, während die Nutzung von Wasser aus dem Ohio Fluß jährlich in 2.000 t CO2-e, und von Wasser aus dem Seneca See 4.500 t CO2-e resultierte. Selbstverständlich hätte die Verringerung der Nutzung sauberen Süßwassers andere Umweltvorteile.ResumenEn vista del cambio climático, los combustibles en base carbón tienen menor demanda. Gas natural está siendo percibido como un combustible de transición, produciendo menos CO2 en la combustión que el carbón, pero no es una fuente renovable. Formaciones de esquistos bituminosos ricos en hidrocarburos, gas natural condensado, potencial de producción de petróleo y la extracción de estos compuestos ha permitido que EEUU se convirtiera en uno de los mayores productores globales de gas natural. Las perforaciones horizontales y la fractura hidráulica están siendo usados para extraer el gas de los esquistos bituminosos, pero la fractura hidráulica de un pozo requiere entre 7 y 19 millones L de agua. Una de las opciones que está siendo explorada es el uso de agua de mina tratada como una alternativa frente al agua dulce. Las formaciones de esquistos bituminosos Marcellus y Utica están en el subsuelo de buena parte de EEUU oriental y el esquisto Utica es requerido por su alto potencial en gas natural en Ohio oriental. Los permisos para pozos están siendo aprobados pero la preocupación sobre la fuente de agua para fractura hidráulica se está incrementando. Analizamos las huellas de carbón de tres fuentes de agua diferentes: agua de mina tratada de Corning, Ohio, agua dulce del Río Ohio y agua dulce del Lago Seneca cerca del sitio del pozo. Las emisiones de CO2 para cada fuente fueron calculadas durante el bombeo, transporte y tratamiento de agua para el uso del pozo una vez y para el uso anual. Se calculó también la producción primaria que ocurrió después de la remoción de la descarga de mina o la reducción debido a la extracción de fuentes de agua dulce. Anualmente, usando agua de mina tratada se emitirían 110.000 t de CO2-e (CO2 equivalente) si se transportara hasta una planta de tratamiento o 90.000 t de CO2-e si se tratara en el sitio, mientras que usando agua del Río Ohio se emitirían 2.000 t de CO2-e y usando agua del Lago Seneca se emitirían 4.500 t de CO2-e, anualmente. Por supuesto, el descenso de la cantidad de agua dulce contaminada usada tiene otros beneficios ambientales.

Predicting mayfly recovery in acid mine-impaired streams using logistic regression models of in-stream habitat and water chemistry

Mayflies (Order Ephemeroptera) require high quality water and habitat in streams to thrive, so their appearance after restoration is an indicator of ecological recovery. To better understand the importance of restoring in-stream habitat versus water chemistry for macroinvertebrate communities, we developed taxon-specific models of occurrence for five mayfly genera (Caenis, Isonychia, Stenonema, Stenacron, and Baetis) inhabiting streams in the Appalachian Mountains, USA. Presence/absence records from past decades were used to develop single and multiple logistic predictive models based on catchment characteristics (drainage area, gradient), in-stream habitat variables (e.g., substrate, channel morphology, pool and riffle quality), and water chemistry. Model performance was evaluated using (a) classification rates and Hosmer-Lemeshow values for test sets of data withheld from the original model-building dataset and (b) a field comparison of predicted versus observed mayfly occurrences at 53 sites in acid mine drainage-impaired watersheds in 2012. The classification accuracies of final models for Caenis, Stenacron, and Baetis ranged from 50 to 75%. In-stream habitat features were not significant predictor variables for these three taxa, only water chemistry. Models for Isonychia and Stenonema had higher classification rates (81%) and included both habitat and chemical variables. However, actual occurrences of Isonychia and Stenonema at study sites in 2012 were low, consistent with the calculated probability of occurrence (Po) < 0.60. Caenis occurred at test sites 35% of the time when the model predicted a Po > 0.40. Stenacron showed the greatest consistency of actual versus predicted occurrences, occurring at 56% of sites when the Po (based on pH and conductivity) was > 0.50 and only at 1 site when Po < 0.5. The results demonstrate how predictive models of individual indicator taxa could be valuable for evaluating the relative impacts of restoring physical habitat versus water chemistry during stream remediation.