Effects of coal fly ash on tree swallow reproduction in Watts Bar Reservoir, Tennessee

Abstract

Coal‐fly ash was released in unprecedented amounts (4.1 × 106 m3) into the Emory River from the Tennessee Valley Authority Kingston Fossil Plant on Watts Bar Reservoir in Tennessee. Tree swallows were exposed to ash‐related constituents at the ash release via their diet of emergent aquatic insects, whose larval forms can accumulate constituents from submerged river sediments. Reproduction of tree swallow colonies was assessed over a 2‐year period by evaluating whether 1) ash constituent concentrations were elevated in egg, eggshell, and nestling tissues at colonies near ash‐impacted river reaches compared to reference colonies, 2) production of fledglings per nesting female was significantly lower in ash‐impacted colonies versus reference colonies, and 3) ash constituent concentrations or diet concentrations were correlated with nest productivity measures (clutch size, hatching success, and nestling survival, and fledglings produced per nest). Of the 26 ash constituents evaluated, 4 (Se, Sr, Cu, and Hg) were significantly elevated in tissues potentially from the ash, and 3 (Se, Sr, and Cu) in tissues or in swallow diet items were weakly correlated to at least one nest‐productivity measure or egg weight. Tree swallow hatching success was significantly reduced by 12%, but fledgling production per nest was unaffected due to larger clutch sizes in the impacted than reference colonies. Bioconcentration from the ash to insects in the diet to tree swallow eggs appears to be low. Overall, adverse impacts of the ash on tree swallow reproduction were not observed, but monitoring is continuing to further ensure Se from the residual ash does not adversely affect tree swallow reproduction over time. Integr Environ Assess Manag 2015;11:56–66. © 2014 SETAC

Evaluating risks to wildlife from coal fly ash incorporating recent advances in metals and metalloids risk assessment

“…Specifically, only 2.4% of the eggs had Se exceeding the lower TRV of 7.7 mg/kg. Except for 1 egg with 13.04 mg/kg, Se in eggs did not exceed the TRV (based on mallard) recommended as more realistic in Adams et al () of 12 to 15 mg/kg (Table ) nor higher TRVs reported for other species in Walls et al (, this issue). Only 1 tree swallow egg exceeded the lower bound of the uncertain TRV range for Cu (11.96 mg/kg in 2009 compared with 10 mg/kg TRV in Table ) and was much lower than the upper bound (20 mg/kg).…”

“…To evaluate whether concentrations of the COPECs in wildlife tissue were linked to the presence of ash, tissue concentrations in ash‐impacted locations were compared with reference area concentrations (Figure ). The evaluation focused on COPECs that were detected in more than 50% of the samples (most >80%; also see Walls et al this issue), with the exception of essential major nutrients (Na, K, Ca, Mg). The full detection limit was used as the sample result for undetected COPECs.…”

“…Data were combined for both years if interaction terms were not significant. Sample sizes for egg and nestling analyses were selected that provided high statistical power (≥80%) with high confidence (≥95%) to detect meaningful differences in mean concentrations among locations (see Walls et al in this issue for map of swallow nest box locations and details on tree swallow analysis).…”

“…Superscripted numbers refer to the following TRV references, and full reference citations are available in the Supplemental Table S5 1 Mora 2003; 2 Walls et al (this issue); 3 Ridgway and Karnofsky ; 4 Andrews et al ; 5 Shore et al 2011; 6 Adams et al ; 7 Beckon et al 2008; 8 Janz et al ; 9 Schwarzbach et al 2006; 10 Mora et al 2011; 11 Hakkinen and Hasanen 1980; 12 Bryan et al ; 13 Burger et al 2002; 14 Rees 1979; 15 Yokel 1982; 16 Yokel 1987; 17 Fowler et al 1979; 18 ATSDR 2007; 19 Clark et al ; 20 Friberg et al 1979; 21 Hamilton et al 1973; 22 Kucera et al 1979.…”

“…Walls et al (, this issue) provides details for the tree swallow study and analysis. In summary, Se, Hg, Cu, and Sr concentrations were significantly higher in tree swallow eggs from at least 1 of the ash‐impacted colonies than for those from at least 1 of the reference colonies.…”