Levels, source appointment, and ecological risk of petroleum hydrocarbons in tropical coastal ecosystems (northeast Brazil): Baseline for future monitoring programmes of an oil spill area

We reviewed 20 years of levels, sources, and environmental risks related to the main petroleum hydrocarbons in the northeast region of Brazil. The aim of this study was to conduct a systematic review to serve as a comprehensive baseline for future monitoring programmes related to the oil spill disaster in 2019/2020. Most contamination levels of both PAHs and AHs were classified as low, except those in specific areas influenced by human activities, such as ports, highly urbanised mangroves, or rivers of medium-sized cities with inadequate liquid and solid waste treatment. Most hydrocarbons were linked to natural sources and burning processes, except in regions of extraction activities and petrochemical facilities as well as highly urbanised areas, where degraded petroleum and oil hydrocarbons predominated. Only 2.5% of the samples exceeded threshold effect levels for Sigma(16-PAHs) and no samples exceeded probable effect levels. When regional threshold levels were used, however, the probable effect for the Sigma(16-PAHs) measured was high, ranging from 5.8 to 6.1%. The few studies reporting biological responses showed that hydrocarbons from anthropogenic sources can induce adverse effects on marine organisms even at low to moderate levels. As the region has recently received a considerable quantity of crude oil, studies should be prioritised for a more precise assessment of the impact of this oil spill.

Automated summary

This study reviewed 20 years of levels, sources, and environmental risks of the main petroleum hydrocarbons in the northeast region of Brazil. The contamination levels were mostly classified as low, except in specific areas influenced by human activities. Most hydrocarbons were linked to natural sources and burning processes, but in regions of extraction activities, petrochemical facilities, and highly urbanized areas, degraded petroleum and oil hydrocarbons were dominant. Only a small percentage of samples exceeded threshold effect levels, and no samples exceeded probable effect levels. The few studies that reported biological responses showed that anthropogenic hydrocarbons can have adverse effects on marine organisms even at low to moderate levels. Further studies should be prioritized to assess the impact of the recent oil spill in the region more precisely.