engleski

Assessment of adverse effects of olive mill waste water and olive mill waste contaminated soil on springtail Folsomia candida

The olive oil industry generates considerable amounts of olive mill wastewater (OMW) which is treated and used in agriculture, energy production, or discharged into evaporating ponds where OMW contaminated soil (OMWS) is formed. Due to the extremely high phenol content, untreated OMWS is not suitable for plants and soil organisms. Collembolans are an extremely important group of non-target soil organisms that are frequently used in ecotoxicological research. However, information on the impact of OMW on the collembolan species F. candida is scarce. Therefore, this study aimed to determine the effects of OMW and OMWS on survival, reproduction, neurotoxicity, oxidative stress, and available energy in springtail F. candida. Exposure to different ratios of OMW and OMWS showed a higher toxicity of OMWS in terms of survival (LC50=32.34 % of OMW ; LC50=45.36 % of OMWS) and reproduction (EC50=10.10 % of OMW ; EC50=19.44 % of OMWS). The number of juveniles gradually decreased as the ratio of OMW increased. In contrast, exposure to OMWS enhanced the reproduction rates in a lower ratio. However, complete inhibition of reproduction was observed after exposure to the highest ratio of OMWS (50%). Furthermore, neurotoxicity (AChE induction), oxidative stress (SOD, GST and MDA induction), and changes in available energy (decrease in lipid and carbohydrate content) have been observed. These negative effects are probably consequences of the high phenol content specific for OMW and OMWS at higher tested ratios. Namely, at lower ratios, OMW and OMWS served as a food source and had a positive effect on reproduction. Consumption of energy for reproduction, defense against neurotoxicity and oxidative stress has led to metabolism imbalance and consequently to long-term consequences visible at the population level. Obtained results indicate that for the ecotoxicological assessment of different wastes, the incorporation of ecotoxicological tests with non-target soil organisms is crucial. Moreover, it is essential to use different endpoints to gain insight into the exact mechanism of action. Furthermore, the application of OMW and OMWS in small ratios can have a positive effect on non-target soil organisms and consequently cause better quality of the soil. Therefore, more research is needed to monitor the impact of lower concentrations of OMW and OMWS over several generations to allow its safe application.

Collembola ; Reproduction rate ; Oxidative stress ; Phenols ; Olive mill waste ; Contaminated soil

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