Determination of the Toxic Potential of the Formation of Oil-Suspended Particulate Matter Aggregates (OSA) in a Simulated Microscale Experiment

The aggregation of suspended particulate matter (SPM) and oil droplets in environments with specific hydrodynamic energy can lead to the formation of Oil-SPM Aggregates (OSA). A laboratory simulation was conducted in order to examine the possible toxic potential of OSA formation using three different concentrations of particulate material (50, 200, 300 mg/L) in a microscale experiment. The procedure was performed through toxicological testing of acute exposure to determine the LC 50 (lethal concentration 50%) using the microcrustacean Artemia salina as a test organism. Serial dilutions were made from surface and bottom samples in order to characterize different toxicity. The concentration that showed the highest potential toxicity was 200 mg/L, having the same values for surface and bottom (LC 50 7.91%), whereas the concentration with the least toxic potential was 300 mg/L (LC 50 31.5%) for surface samples. Negative correlation was found between redox potential and the hydrogenionic potential (only for samples with 200 mg/L of sediment), and positive correlation was found between toxicity factors (percent dilution and mortality) and the other monitored parameters.