RESUMEN
The effluent produced during hydraulic fracturing (i.e. flowback and produced water; FPW), is a complex hyper-saline solution that is known to negatively impact the survival and the fitness of the water flea Daphnia magna, but to date effects on behavior are unstudied. In the current study, the effects of FPW on phototactic behavior of D. magna were examined. Exposure of naïve animals to FPW resulted in a dose-dependent increase in the speed of appearance of daphnids in the illuminated zone of the test apparatus (i.e. a faster positive phototaxis response). A similar dose-dependent response was observed in a test solution where the salt content of FPW was recreated in the absence of other components, suggesting that the effect was largely driven by salinity. The effect of FPW was significant when the raw FPW sample was diluted to 20% of its initial strength, while the effect of salt-matched solution was significant at a 10% dilution. A distinct effect was observed following FPW pre-exposure. After a 24â¯h pre-exposure to 1.5% FPW, Daphnia displayed a significantly inhibited positive phototaxis response when examined in control water, relative to control animals that were not pre-exposed to FPW. This effect was not observed in salinity pre-exposed animals, however these daphnids displayed a significantly reduced phototactic response when tested in saline waters, indicating a loss of the positive phototaxis seen in naïve organisms. These data indicate that FPW can induce perturbations in the behavior of aquatic invertebrates, an effect that may influence processes such as feeding and predation rates.
Asunto(s)
Daphnia/efectos de los fármacos , Fracking Hidráulico , Luz , Fototaxis/efectos de los fármacos , Aguas Residuales/química , Contaminantes Químicos del Agua/toxicidad , Animales , Daphnia/fisiología , Daphnia/efectos de la radiación , Modelos Teóricos , Salinidad , Contaminantes Químicos del Agua/análisisRESUMEN
Flowback and produced water (FPW) is a complex, often brackish, solution formed during the process of hydraulic fracturing. Despite recent findings on the short-term toxicity of FPW on aquatic biota, longer-term impacts of FPW on fish have not yet been investigated and the mechanisms of chronic effects remain unknown. The aim of the present study was to observe the effect of a diluted FPW on ionoregulatory endpoints in the rainbow trout Oncorhynchus mykiss, following a 28-d sub-chronic exposure. A salinity-matched control solution (SW), recreating the salt content of the FPW, was used to differentiate the specific effect of the salts from the effects of the other FPW components (i.e. organics and metals). Overall, fish ionoregulation was not impacted by the chronic exposure. An accumulation of strontium (Sr) and bromide (Br) occurred in the plasma of the FPW-exposed fish only, however no change of plasma ions (Na, K, Cl, Ca, Mg) was observed in SW- or FPW-exposed fish. Similarly, exposures did not alter branchial activity of the osmoregulatory enzymes sodium/potassium ATPase and proton ATPase. Finally, FPW exposure resulted in modifications of gill morphology over time, with fish exposed to the fluid displaying shorter lamellae and increased interlamellar-cell mass. However, these effects were not distinct from morphological changes that also occurred in the gills of control groups.
Asunto(s)
Monitoreo del Ambiente/métodos , Branquias/efectos de los fármacos , Fracking Hidráulico , Oncorhynchus mykiss/metabolismo , Contaminantes Químicos del Agua/toxicidad , Animales , Cloruros/sangre , Branquias/enzimología , Branquias/patología , Modelos Teóricos , Oncorhynchus mykiss/sangre , Ósmosis , Sodio/sangre , ATPasa Intercambiadora de Sodio-Potasio/metabolismo , Pruebas de Toxicidad Aguda , Pruebas de Toxicidad SubcrónicaRESUMEN
Thirteen states in the United States allow the spreading of O&G wastewaters on roads for deicing or dust suppression. In this study, the potential environmental and human health impacts of this practice are evaluated. Analyses of O&G wastewaters spread on roads in the northeastern, U.S. show that these wastewaters have salt, radioactivity, and organic contaminant concentrations often many times above drinking water standards. Bioassays also indicated that these wastewaters contain organic micropollutants that affected signaling pathways consistent with xenobiotic metabolism and caused toxicity to aquatic organisms like Daphnia magna. The potential toxicity of these wastewaters is a concern as lab experiments demonstrated that nearly all of the metals from these wastewaters leach from roads after rain events, likely reaching ground and surface water. Release of a known carcinogen (e.g., radium) from roads treated with O&G wastewaters has been largely ignored. In Pennsylvania from 2008 to 2014, spreading O&G wastewater on roads released over 4 times more radium to the environment (320 millicuries) than O&G wastewater treatment facilities and 200 times more radium than spill events. Currently, state-by-state regulations do not require radium analyses prior to treating roads with O&G wastewaters. Methods for reducing the potential impacts of spreading O&G wastewaters on roads are discussed.