The mysterious oil spill in the northeastern coast of Brazil: tracking offshore seawater and the need for improved vessel facilities

A scientific cruise between November 15 and December 18, 2019 aboard RN Vital de Oliveira collected offshore seawater samples at 59 stations between the states of Ceara and Bahia. The objective was to identify hydrocarbon levels potentially associated with the mysterious oil spill that reached the northeastern coast of Brazil. Median concentrations of aliphatic hydrocarbons (AHs, 0.79 mu g L-1) and polycyclic aromatic hydrocarbons (PAHs, 5.39 ng L-1) do not indicate contamination by crude oil and are comparable to baseline levels previously found in other areas of the Brazilian continental margin. The detailed composition of both groups of hydrocarbons revealed that some samples were contaminated during sampling and/or handling on-board. The data set presented herein highlights the difficulty in tracking small oil patches spread over a huge ocean area and, more importantly, the need for improving protocols of national research vessels used to collect seawater samples for trace organic analyses.

Automated summary

A scientific cruise in northeastern Brazil collected seawater samples to study the hydrocarbon levels related to an oil spill. The results show that the levels of hydrocarbons in the samples were not contaminated by crude oil and were comparable to baseline levels in other areas. However, some samples were contaminated during the sampling and handling process. The study highlights the need to improve protocols for collecting seawater samples for trace organic analyses on research vessels.