Bioassays with terrestrial and aquatic species as monitoring tools of hydrocarbon degradation

Abstract

In this study chemical analyses and ecotoxicity tests were applied for the assessment of a heavily hydrocarbon-contaminated soil prior and after the application of a remediation procedure that consisted in the stimulation of soil autochthonous populations of hydrocarbon degraders in staticventilated biopiles. Terrestrial bioassays were applied in mixtures of test soils and artificial control soil and studied the survival and reproduction of Eisenia fetida and the avoidance response of E. fetida and Folsomia candida. Effects on aquatic organisms were studied by means of acute tests with Vibrio fischeri, Raphidocelis subcapitata and Daphnia magna performed on aqueous elutriates from test soils. The bioremediation procedure led to a significant reduction in the concentration of hydrocarbons (from 34264 mg kg -1 to 3074 mg kg -1 i.e. 91% decrease) and toxicity although bioassays were not able to report a percentage decrease of toxicity as high as the percentage reduction. Sublethal tests proved the most sensitive terrestrial bioassays and avoidance tests with earthworms and springtails showed potential as monitoring tools of hydrocarbon remediation due to their high sensitivity and short duration. The concentrations of hydrocarbons in water extracts from test soils were 130 µg L -1 and 100 µg L -1 before and after remediation, respectively. Similarly to terrestrial tests, most aquatic bioassays detected a significant reduction in toxicity, which was almost negligible at the end of the treatment. D. magna survival was the most affected by soil elutriates although toxicity to the crustacean was associated to the salinity of the samples rather than to the concentration of hydrocarbons. Ecotoxicity tests with aqueous soil elutriates proved less relevant in the assessment of hydrocarbon-contaminated soils due to the low hydrosolubility of hydrocarbons and the influence of the physicochemical parameters of the aquatic medium.

Assessing potential aquatic toxicity of airport runoff using physicochemical parameters and Lemna gibba and Aliivibrio fischeri bioassays

“…This low sensitivity is rather surprising since the A. fischeri luminescent test is susceptible to many different compounds (Kaiser and Palabrica, 1991 ) and widely accepted as a good indicator of the environmental impact of certain wastes and leachates produced by human activity (Roig et al, 2012 ; Zhou et al, 2017 ). Lower toxicity values have also been obtained in runoff samples from a waste landfill (Melnyk et al, 2014 ) and hydrocarbon-contaminated soils (Bori et al, 2016 ).…”

“…However, these analyses do not allow the assessment of ecotoxicological impacts of pollutant mixtures and neither the possible interaction among them (Cancilla et al, 2003 ; Pillard, 1995 ). Bioassays are a valuable option for assessing the ecotoxicological impacts of chemicals in complex water samples (Bori et al, 2016 ; Hongxia et al, 2004 ). Lemna gibba (Brain et al, 2004 ; Greenberg et al, 1992 ; Mihaich et al, 2009 ; Nunes et al, 2014 ) and Aliivibrio fischeri bioassays have been used in ecotoxicological studies to investigate aquatic toxicity of a variety of pollutants (Reemtsma et al, 1999 ).…”

Avaliações cito e ecotoxicológicas dos fotossensibilizadores fenotiazínicos atualmente utilizados no tratamento fotodinâmico antimicrobiano

“…Apesar da inegável utilidade dos estudos de citotoxicidade, nem sempre os seus resultados podem ser diretamente extrapolados para organismos inteiros (HEGER et al, 2018;TRUONG et al, 2011). Desse modo, etapas importantes da avaliação do risco ambiental são as análises da toxicidade aquática e terrestre e da bioacumulação dos agentes químicos de interesse em organismos-modelo (BORI et al, 2016;BUSQUET et al, 2014;MARTINS et al, 2007).…”

“…Na determinação da toxicidade aquática, normalmente são avaliados os efeitos das substâncias em organismos aquáticos de diferentes níveis tróficos: produtores, normalmente algas; consumidores invertebrados, como protozoários ou microcrustáceos; e consumidores vertebrados, como peixes (HEGER et al, 2018;ROCHA et al, 2017;BORI et al, 2016). Inicialmente, são feitos ensaios para avaliar a toxicidade aguda da substância.…”

“…Nos ensaios para avaliar a toxicidade aguda, normalmente são utilizados microcrustáceos do gênero Daphnia e peixes, como Danio rerio (HEGER et al, 2018;ROCHA et al, 2017;BORI et al, 2016;BUSQUET et al, 2014;MARTINS et al, 2007).…”