Selenium Speciation in Coal Ash Spilled at the Tennessee Valley Authority Kingston Site

Liu, Yuting; Chen, Tsan‐Yao; Mackebee, William Greer; Ruhl, Laura; Vengosh, Avner; Hsu‐Kim, Heileen

doi:10.1021/es4041557

Cited by 42 publications

(49 citation statements)

References 36 publications

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“…Arsenic associated with coal ash exists mainly as As(V) species while Se is typically found as Se(IV) and elemental Se(0) species (Chappell et al, 2014;Deonarine et al, 2015;Huggins et al, 2007;Liu et al, 2013). The mobilization of As and Se from coal ash is typically assessed using deionized water under aerobic conditions and perhaps under a wide range of pH values (Bednar et al, 2010;Izquierdo and Querol, 2012;Liu et al, 2013;Thorneloe et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Much less attention has been given to redox transformations that can occur during ash disposal, even though these processes are critical for As and Se mobilization, as stated above. Two studies have attempted to address redox conditions by taking ash-deionized water mixtures and purging a subset with nitrogen gas (Bednar et al, 2010;Liu et al, 2013). The results of the work showed no or minimal differences between the oxic and N 2 -purged mixtures with respect to As and Se redox speciation and leaching potential from the ash.…”

Section: Introductionmentioning

confidence: 99%

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Leaching potential and redox transformations of arsenic and selenium in sediment microcosms with fly ash

Schwartz

Rivera

Lee

et al. 2016

Applied Geochemistry

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The unintended release of coal ash to the environment is a concern due to the enrichment of contaminants such as arsenic (As) and selenium (Se) in this solid waste material. Current risk assessments of coal ash disposal focus on pH as the primary driver of leaching from coal ash. However, redox speciation of As and Se is a major factor for their mobilization potential and has received much less attention for risk assessments, particularly in disposal scenarios where coal ash will likely be exposed to microbially-driven redox gradients. The aim of this study was to demonstrate the differences of aerobic and anaerobic conditions for the leaching of As and Se from coal ash. Batch sediment-ash slurry microcosms were performed to mimic an ash spill scenario and were monitored for changes in As and Se speciation and mobilization potential. The results showed that the dissolved As concentrations were up to 50 times greater in the anaerobic microcosms relative to the aerobic microcosms during the two week incubation. This trend was consistent with As redox speciation determined by X-ray absorption spectroscopy, which indicated that 55% of the As in the solid phase at the end of the experiment was present as As(III) (a more leachable form of arsenic relative to As(V)). In the aerobic microcosms, only 13% of the As was As(III) and the rest was As(V). More than half of the Se was present as Se(IV) in the original fly ash and in the aerobic microcosms, while in the anaerobic microcosms Se was gradually transformed to less soluble Se(0) species. Likewise, dissolved Se concentrations were up to 25 times greater in the aerobic microcosms relative to anaerobic conditions. While the overall observations of As and Se mobilization potential from coal ash were consistent with expectations for aqueous and solid phase speciation of these elements, the findings directly show the relevance of these processes for coal ash disposal. These results highlight the need to select appropriate environmental parameters to include in risk assessments as well as provide potential geochemical monitoring tools through the use of dissolved Se/As ratios to determine the redox conditions of ash storage and spill sites.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Leaching potential and redox transformations of arsenic and selenium in sediment microcosms with fly ash

Schwartz

Rivera

Lee

et al. 2016

Applied Geochemistry

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“…As unfortunate as the spill was, it provided an opportunity to directly study the impact of coal fly ash in a large lotic system where the amount of downstream transport of ash was also being investigated and monitored (TVA 2010b). Previous research on the Kingston spill has provided insight on the contaminants of concern from multiple perspectives including sediment biogeochemistry, metal speciation, and metal bioaccumulation across multiple organisms (Ruhl et al 2010;Bednar et al 2010;Ruhl et al 2009;Otter et al 2013;Deonarine et al 2013;Bartov et al 2012;Liu et al 2013;Beck et al 2013;Souza et al 2013). Otter et al (2012) showed elevated concentrations of arsenic and selenium in various tissues of multiple fish species at ash-associated sites compared to reference sites.…”

Section: Discussionmentioning

confidence: 99%

“…As long as residual ash exists in the Emory River (or downstream), the potential for changes in metal binding and/or changes in speciation leading to differing leaching dynamics exists. Previous work, including studies focused on the Kingston spill site, have shown that river conditions play a major role influencing the bioaccumulation of metals known to be present in coal ash (Ruhl et al 2010;Bednar et al 2010;Ruhl et al 2009;Deonarine et al 2013;Liu et al 2013). Therefore, it is recommended that a holistic long-term monitoring plan be utilized to fully understand the longterm impacts of this spill and minimize risk.…”

Section: Discussionmentioning

confidence: 99%

Bioaccumulation of metals in three freshwater mussel species exposed in situ during and after dredging at a coal ash spill site (Tennessee Valley Authority Kingston Fossil Plant)

Otter

McKinney

Brown

et al. 2015

Environ Monit Assess

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On December 22, 2008, a dike containing coal fly ash at the Tennessee Valley Authority Kingston Fossil Plant (TN, USA) failed, and within months, dredging operations began to remove ash-contaminated sediments. The purpose of this study was to investigate differences in the bioaccumulation of metals in three mussel species during and after dredging operations. Mussels were caged for approximately 1 year during dredging and after, and then mussel condition index values and As, Cd, Cr, Pb, Ni, Se, Hg, U, Fe, Mg, Al, Sb, Ba, Be, Co, Cu, Mn, Mo, Ag, Sr, Tl, V, and Zn concentrations in soft tissue were determined via inductively coupled plasma-mass spectrometery. Overall, the differences observed in metal bioaccumulation and mussel health suggest that mussels in the immediate downstream area of the dredging site may have been impacted, as evidenced by a significant decrease in mussel condition index values, but that this impact did not result in increased tissue concentrations of metals.

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“…Se, which occurs naturally as a trace constituent in geologic formations (e.g. Cretaceous black shale in the USA (Kulp and Pratt, 2004;Tuttle et al, 2014a) and associated soils, is currently contaminating watersheds in mining areas (Chuncai et al, 2014;Liu et al, 2013;Vengosh et al, 2013), irrigated alluvial valleys (Bailey et al, 2013;Bailey et al, 2012;Bajaj et al, 2011;Deverel and Gallanthine, 1989;Dhillon and Dhillon, 2003;Gates et al, 2009;Tuttle et al, 2014b), wetlands (Zawislanski et al, 2001;Zhang et al, 2012), and sediments (Beisner et al, 2009;Guan and Martin, 1991;Masscheleyn et al, 1990;Oremland et al, 1989)……”

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confidence: 99%

Tracking selenium in the Chalk aquifer of northern France: Sr isotope constraints

Cary¹,

Benabderraziq²,

Elkhattabi³

et al. 2014

Applied Geochemistry

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International audienceGroundwater at the southern and eastern edges of France's Paris Basin has a selenium content that at times exceeds the European Framework Directive's drinking-water limit value of 10 µg/L. To better understand the dynamics of the Chalk groundwater being tapped to supply the city of Lille and the Se origins, we used a combination of geochemical and isotopic tools. Strontium isotopes, coupled with Ca/Sr, Mg/Sr and Se/Sr ratios, were used to identify the main groundwater bodies and their mixings, with the Mg/Sr ratio constraining a ternary system. Groundwater in the agricultural aquifer-recharge zone represents a first end-member and displays the youngest water ages of the catchment along with the highest strontium isotopic signature (0.7084) and low Se contents. Anaerobic groundwater constitutes a second major end-member affected by water-rock interactions over a long residence time, with the lowest strontium isotopic signature (0.7079) and the lowest Se content, its low SF6 content confirming the contribution of old water. Se-rich groundwater containing up to 30 µg/L of Se represents a third major end-member, with an intermediate Sr isotopic ratio, and is mainly constrained by the clayey Se-rich formation overlying the Chalk aquifer. The spatial and temporal Se variability in the groundwater is clearly linked to the presence of this formation identified as Tertiary and also to the hydrological conditions; saturation of the Se-rich clays by oxygenated groundwater enhances Se mobility and also Sr adsorption onto the clays. This multi-tool study including Sr isotopes successfully identified the Se origins in the aquifer and has led to a better understanding of the regional mixing and processes affecting the Chalk groundwater

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Selenium Speciation in Coal Ash Spilled at the Tennessee Valley Authority Kingston Site

Cited by 42 publications

References 36 publications

Leaching potential and redox transformations of arsenic and selenium in sediment microcosms with fly ash

Leaching potential and redox transformations of arsenic and selenium in sediment microcosms with fly ash

Bioaccumulation of metals in three freshwater mussel species exposed in situ during and after dredging at a coal ash spill site (Tennessee Valley Authority Kingston Fossil Plant)

Tracking selenium in the Chalk aquifer of northern France: Sr isotope constraints

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