EDITOR'S NOTE:The baseline ecological risk assessment (BERA) of residual coal-fly ash in Watts Bar Reservoir was conducted following a 2008 spill from the Tennessee Valley Authority Kingston Fossil Plant (Roane County, TN). Results of the BERA were used to focus the long-term management strategy for the impacted river system. This article is among 7 peer-reviewed articles in the special series, "Ecological Risk Assessment for Residual Coal Fly Ash at Watts Bar Reservoir, Tennessee." The series includes articles presenting the following: problem formulation for the river system; sediment toxicity test procedures; benthic community analysis techniques; methods used to evaluate risks to benthic organisms, fish, and riparian and aquatic wildlife; an extensive analysis characterizing risk to insectivorous birds; and finally, how the BERA results influenced management decisions. ABSTRACTA baseline ecological risk assessment (BERA) was performed for residual ash in the Watts Bar Reservoir following a release of fly ash from the Tennessee Valley Authority (TVA) Kingston Fossil Plant. The site consists of parts of 3 rivers in eastern Tennessee comprising over 32 river kilometers. The purpose of the assessment was to determine if residual ash negatively impacts maintenance and reproduction of balanced communities or populations of potentially exposed ecological receptor groups in these rivers. This introductory article summarizes the site and environmental setting, assessment and measurement endpoints, risk characterization methods, and the study approach. Subsequent articles describe ecological risks to fish, benthic invertebrates, aquatic-and riparian-feeding wildlife, and aerial-feeding insectivores; and the role ecological risk characterization played in determining the most effective management of the residual ash, setting project remediation objectives and targets, and designing long-term monitoring to measure the effectiveness of the selected removal action. Integr Environ Assess Manag 2015;11:32-42. © 2014 SETAC

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In December 2008, 4.1 million cubic meters of coal ash were released into the Emory and Clinch Rivers by the Tennessee Valley Authority Kingston Fossil Plant. Coal ash contains several contaminants, including the bioaccumulative metalloid selenium (Se). Because Se is predominantly accumulated in aquatic organisms through dietary rather than aqueous exposure, tissue-based toxicity thresholds for Se are currently being considered. The proposed threshold concentrations range between 4 μg/g and 9 μg/g Se (dry wt.) in whole body fish, with a proposed fillet threshold of 11.8 μg/g. In the present study, the authors examined the spatial and temporal trends in Se bioaccumulation and examined the relationship between the Se content in fillets and in whole bodies of fish collected around the Kingston spill site to determine whether Se bioaccumulation was a significant concern at the ash spill site. Whereas Se concentrations in fish (whole bodies and fillets) were elevated at sampling locations affected by the Kingston ash spill relative to reference locations, concentrations do not appear to be above risk thresholds and have not been increasing over the 5-yr period since the spill. These findings are not only relevant to guiding the human health and ecological risk assessments at the Kingston ash spill site, but because of current national discussions on appropriate guidelines for Se in fish as well for the disposal of coal combustion wastes, the results are also relevant to the general understanding of Se bioaccumulation in contaminated water bodies.

The Tennessee Valley Authority conducted a Baseline Ecological Risk Assessment (BERA) for the Kingston Fossil Plant ash release site to evaluate potential effects of residual coal ash on biota in Watts Bar Reservoir, Tennessee. The BERA was in response to a release of 4.1 million m3 of coal ash on December 22, 2008. It used multiple lines of evidence to assess risks for 17 different ecological receptors to approximately 400 000 m3 of residual ash in the Emory and Clinch rivers. Here, we provide a brief overview of the BERA results and then focus on how the results were used to help shape risk management decisions. Those decisions included selecting monitored natural recovery for remediation of the residual ash in the Emory and Clinch rivers and designing a long‐term monitoring plan that includes adaptive management principles for timely adjustment to changing conditions. This study demonstrates the importance of site‐specific ecological data (e.g., tissue concentrations for food items, reproductive data, and population data) in complex ecological risk assessments. It also illustrates the value of the US Environmental Protection Agency's (USEPA) data quality objectives process in building consensus and identifying multiple uses of results. The relatively limited adverse effects of this likely worst‐case scenario for ash‐related exposures in a lotic environment provide important context for the USEPA's new coal combustion residue disposal rules. Integr Environ Assess Manag 2015;11:80–87. © 2014 SETAC

The weathering of coal combustion products (CCPs) in a lotic environment was assessed following the Tennessee Valley Authority (Kingston, TN) fly ash release of 2008 into surrounding rivers. Sampled materials included stockpiled ash and sediment collected from 180 to 880 days following the release. Total recoverable concentrations of heavy metals and metalloids in sediment were measured, and percent ash was estimated visually or quantified by particle counts. Arsenic and selenium in sediment were positively correlated with percent ash. For samples collected 180 days after the release, total concentrations of trace elements downstream of the release were greater than reference levels but less than concentrations measured in stockpiled ash. Total concentrations of trace elements remained elevated in ash-laden sediment after almost 2.5 years. A sequential extraction procedure (SEP) was used to speciate selected fractions of arsenic, copper, lead, nickel, and selenium in decreasing order of bioavailability. Concentrations of trace elements in sequentially extracted fractions were one to two orders of magnitude lower than total recoverable trace elements. The bulk of sequentially extractable trace elements was associated with iron-manganese oxides, the least bioavailable fraction of those measured. By 780 days, trace element concentrations in the SEP fractions approached reference concentrations in the more bioavailable water soluble, ion exchangeable, and carbonate-bound fractions. For each trace element, the percentage composition of the bioavailable fractions relative to the total concentration was calculated. These SEP indices were summed and shown to significantly decrease over time. These results document the natural attenuation of leachable trace elements in CCPs in river sediment as a result of the loss of bioavailable trace elements over time.

Under a consent agreement among the Environmental Protection Agency (EPA) and proponents both for and against stricter regulation, EPA is to issue a new coal ash disposal rule by the end of 2014. Laboratory toxicity investigations often yield conservative estimates of toxicity because many standard test species are more sensitive than resident species, thus could provide information useful to the rule-making. However, few laboratory studies of coal ash toxicity are available; most studies reported in the literature are based solely on field investigations. This brief communication describes a broad range of toxicity studies conducted for the Tennessee Valley Authority (TVA) Kingston ash spill, results of which help provide additional perspective on the toxicity of coal ash. Integr Environ Assess Manag 2015;11:5-9. © 2014 SETAC

Levels of boron in Florida natural waters are generally low, (median value <50 µg/liter for 120 samples) and not of toxic concern. However, municipal sewage effluents have levels high enough (150–800 µg/liter) to cause phytotoxicity, at least to sensitive plants such as citrus. Detergent use of borate softeners and perborate bleaches is evidently the source of the elevated boron levels in sewage. Boron concentrations in rainfall increase with proximity to either coast in peninsular Florida, reaching levels of 80–90 µg/liter. Marine aerosols are thus implicated as an important natural source in the boron cycle of Florida. Model ecosystem studies indicated little bioaccumulation and no toxic hazard at levels expected in natural waters. Interactions of boron with clays and with dissolved organic color (humates) were found to be small, and boron behaves as an essentially conservative element in natural waters.

Investigating the ecological impacts of contaminants released into the environment requires integration of multiple lines of evidence. Collection and analysis of interstitial water is an often-used line of evidence for developing benthic exposure estimates in aquatic ecosystems. It is a well-established principle that chemical and toxicity data on interstitial water samples should represent in-situ conditions; i.e., sample integrity must be maintained throughout the sample collection process to avoid alteration of the in-situ geochemical conditions. Unfortunately, collection and processing of pore water is not standardized to address possible geochemical transformations introduced by atmospheric exposure. Furthermore, there are no suitable benchmarks (ecological or human health) against which to evaluate adverse effects from chemicals in pore water; i.e., empirical data is lacking on the toxicity of inorganic contaminants in sediment interstitial water. It is clear that pore water data is best evaluated by considering the bioavailability of trace elements and the partitioning of contaminants between the aqueous and solid phases. It is also evident that there is a need for sediment researchers and regulatory agencies to collaborate in developing a standardized approach for sediment/pore water collection and data evaluation. Without such guidelines, the number of different pore water collection and extraction techniques will continue to expand, and investigators will continue to evaluate potentially questionable data by comparison to inappropriate criteria.