Formation of OSA and dispersion of polycyclic aromatic hydrocarbons in a tropical estuary as a tool in the prevention of environmental impacts: influence of the biogeochemical characteristics of the estuary.

The formation of an oil-suspended particulate material aggregate (OSA) is one of the weathering processes that occur after the spill of oil in marine environments, responsible for the dispersion of hydrocarbons. Oil and particle aggregates are formed from the interaction between small oil droplets and suspended particulate matter (SPM). In general, SPM are fine particles which may be inorganic minerals or organic particles in the water column. OSAs provide vertical dispersion of oil along the water column depending on the acquired density (buoyancy), and may remain near the surface, water column, or bottom of water bodies. The present study examines the formation of these aggregates through the laboratory simulation of an oil spill in the waters of the São Paulo river estuary. The main objective was to investigate the dispersion of polycyclic aromatic hydrocarbons (PAHs), verifying which estuary characteristics most influenced the formation of OSAs and in addition to determine the regions of probable ecotoxicological impact due to the negative buoyancy of the formed aggregate. The results show that there was greater dispersion to the water column, mainly of lighter PAHs, ranging from 85,804.05 ng g-1 (P11C) to 566,989.84 ng g-1 (P17C). The percentage of dispersed PAH concentration per experimental unit ranged from 9.90% in unit P2 to 75.27% in unit P18. The formation of OSAs was influenced mainly by salinity and chlorophyll a. As the most vulnerable regions, the impacts are one mouth (P2 and P4), one central region (P7, P8, and P10), and one source (P18).

Research of OSA seasonal training in the São Paulo River, BTS: a tool to prevent potential ecotoxicological impacts.

Oil exploitation, the basis of the world energy sector, is linked to risks and accidents, causing damage to the affected regions. Oil-suspended particulate matter aggregate (OSA) is a promising technology to mitigate those effects. The present study periodically (February 2016 and July 2016) evaluated the dispersion of oil at 28 points in the São Paulo River's estuary, Todos os Santos Bay, Brazil, analyzing the influence of suspended particulate matter (SPM), particulate organic carbon (POC), ions, and chlorophyll on the formation OSA, targeting the prediction of possible ecotoxicological risks. The results showed that the estuary presented similar characteristics in the expeditions, reflecting the oil dispersion pattern through the formation of OSAs, being 92.86% dispersed in the column in the first and 85.71% in the second expedition. The results also pointed to the possibility of pollution in the food chain, reduced fertility, the emergence of abnormalities and the gradual disappearance of species across the whole river in a possible oil spill.