Oil dispersion increases the apparent bioavailability and toxicity of diesel to rainbow trout (Oncorhynchus mykiss)

Abstract

Diesel is a complex mixture containing polycyclic aromatic hydrocarbons, which persist after a spill, pass readily from water into tissues, and are toxic to early life stages of fish. The bioavailability and chronic toxicity of hydrocarbons dissolved into water from floating diesel (water-accommodated fraction) and chemically dispersed diesel (chemically enhanced water-accommodated fraction) were measured by the extent of ethoxyresorufin-O-deethylase (EROD) induction in juvenile rainbow trout (Oncorhynchus mykiss) and by the severity of blue sac disease in embryos. The water-accommodated fraction of floating diesel was virtually nontoxic to embryos at nominal concentrations up to 1,000 mg/L, causing only small weight changes. Liver EROD induction in juvenile trout was only observed at the highest nominal water-accommodated fraction concentration (10,000 mg/L). Chemical dispersion increased the bioavailability and toxicity of diesel to trout by 100-fold. Diesel chemically enhanced water-accommodated fraction induced EROD activity, caused blue sac disease, and impaired development and growth of embryonic trout at nominal concentrations as low as 10 mg/L; 88% mortality occurred at 100 mg/L. However, when total hydrocarbon concentrations were measured, differences between dispersed and undispersed diesel disappeared, with a median lethal concentration of 8 mg/L of total hydrocarbons and sublethal median effective concentrations ranging from 1.3 to 6.1 mg/L. Dispersion of diesel by high-energy mechanical mixing was recently reported to cause acute lethality to juvenile trout between 40 and 200 mg/L. Therefore, dispersion of oil by any means increases the bioavailability and apparent toxicity of diesel to fish embryos without changing the toxicity of its components. Nevertheless, in an actual spill, dispersion of diesel increases the effects of oil on fish populations.

Alterações leucocitárias ocasionadas pelo estresse toxicológico agudo do óleo diesel em juvenis de tilápia-do-nilo

“…A toxicidade do óleo diesel para juvenis de tilápia já foi relatada por NOGUEIRA et al (2011), que constataram a exposição dos juvenis de O. niloticus nas diluições de 0,01 e 0,05% por sete dias, verificando mortalidade de 100% dos peixes no sexto dia de experimento para a maior diluição testada. Já SCHEIN et al (2009), realizando ensaios crônicos com alevinos de truta-arco-íris (Oncorhynchus Mykiss) e usando duas diluições da fração solúvel em água de óleo diesel (0,01 e 1%) ao longo de nove dias, determinaram concentração média de 0,05%. No presente estudo, a concentração letal média a 50% encontrada foi maior que os achados de NOGUEIRA et al (2011) e SCHEIN et al (2009, com mortalidade de 100% em menos de 24 horas.…”

“…O risco ambiental ocasionado pelos derivados de petróleo e a toxicidade aos organismos aquáticos podem estar relacionados com as partes solúveis desses produtos na água (SCHEIN et al, 2009;RODRIGUES et al, 2010). SIMONATO et al (2008) e RODRIGUES et al (2010 aportam que é possí-vel que a mortalidade decorrente da toxicidade do óleo diesel esteja associada com as alterações fisiológicas e morfológi-cas, tais como hiperplasia, aneurisma e necrose nos tecidos, podendo afetar o comportamento dos peixes.…”

Effectiveness and toxicity of oil spill reagents on Artemia Salina

“…19,20 It is important to find solutions that can clean up an oil spill that can be practically used and that are effective. Furthermore, solutions, themselves need to be safe, otherwise, toxicity to marine life can be compounded.…”

“…This mixture was stirred for 10 minutes and left still for 24 hours, to allow for leaching of chemicals from the oil into the water, similar to a method outlined by Schein et al 14 This was replicated three times.…”

Effects of ultraviolet radiation on the toxicity of water-accommodated fraction and chemically enhanced water-accommodated fraction of Hebei Spirit crude oil to the embryonic development of the Manila clam, Ruditapes philippinarum

“…In past, dispersants had adverse effects on ecosystems, but recently developed dispersants contains less toxic effects and accepted as safely applicable. In spite of low toxicity of oil dispersant, it changes the reactivity of hydrocarbons and increases the bioavailability of oil constituents to aquatic organisms so that the toxicity of spilled oil can be increased (Ramachandran et al, 2004;Schein et al, 2009;Wu et al, 2012). Therefore, the effects of UV radiation and oil dispersant must be considered in the assessment of ecotoxicity of spilled oil to aquatic organisms.…”