No abstract

No abstract

The largest environmental release of coal ash in US history occurred in December 2008 with the failure of a retention structure at the Tennessee Valley Authority Kingston Fossil Fuel Plant in East Tennessee. A byproduct of coal-burning power plants, coal ash is enriched in metals and metalloids such as selenium and arsenic with known toxicity to fish embryonic and larval life stages. The early development of fish embryos and larvae during contact exposures to river bottom sediments containing up to 78 % coal ash from the Kingston spill was examined in 7-day laboratory tests with the fathead minnow (Pimephales promelas). No significant effects were observed in hatching success, incidences of developmental abnormalities, or embryo-larval survival. Results suggest that direct exposures to sediment containing residual coal ash from the Kingston ash release may not present a significant risk to fish eggs and larvae in waterways affected by the coal ash spill.

Mitigation strategies can be implemented to decrease chlorinated and non‐chlorinated organic exposures to biota of aquatic receiving systems thereby reducing associated risks. In this work, we investigated the concept of coupling a physical/chemical reactor (i.e. a cavitation reactor) with a biological reactor (i.e. a constructed wetland) in an effort to efficiently transform PCE, TCE, and petroleum in freshwater into non‐toxic chemical forms or concentrations. Rates of TCE degradation due to cavitation ranged from 0.010 to 0.026 min‐1 with corresponding half‐lives of 69 to 27 min. Compared to controls, degradation of petroleum in water by cavitation was not detected in these experiments. After treatment in anaerobic wetland reactors, TCE and PCE decreased by more than 99 % under two flow regimes (5‐d and 20‐d HRT). In reciprocating constructed wetland reactors receiving petroleum, mean COD, BOD5, and total Zn decreased by 90.0, 88.8, and 86.8 %, respectively, in wetland outflows compared to the initial conditions (96‐h HRT). Percent survival (96‐h) of D. magna and P. promelas increased from zero percent in initial conditions to 80.1 (± 18.9) and 80.0 (± 21.4) %, respectively, after treatment in the constructed wetland reactors. The experimental results obtained in the laboratory‐scale set‐up and the theoretical model for the hybrid reactor concept will be used to obtain the intrinsic kinetic coefficients for the appropriate reactors. This kinetic information will be used to scale‐up the hybrid reactor model concept for the same level of pollutant removal.

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