Chemistry and toxicity of produced water (PW) from offshore platforms operated by Petrobras in Brazil were investigated. Three studies -PW monitoring, detailed composition and temporal variability -were conducted during 1996, 2001 and 2006 Median chronic toxicity using Lytechinus variegatus showed a NOEC = 1.3%. These results for Brazilian PW are similar to those for the North Sea, Gulf of Mexico, Australia and other regions of the world. Dispersion plumes modelled using CORMIX and CHEMMAP predicted that PW can be diluted rapidly after discharge and that permissible levels for all chemical parameters in seawater cited in the Brazilian Resolution CONAMA 357/05 are attained within 500 m of the discharge point. Over 10 years (1998-2010) of monitoring in the vicinity of the Brazilian platforms did not show alterations in sea water quality, supporting the predictions of the dispersion plume modelling. Despite no observed alteration in seawater quality around oil and gas production platforms, the authors recognize the importance of continuous evaluation of the impact of PW discharges from a risk assessment perspective, and studies of bioaccumulation and the use of biomarkers, among other initiatives currently implemented by Petrobras in areas with large volumes of PW discharge. Up to and including 2011, Petrobras remains the major producer of oil and gas in Brazil and the total discharge of produced water by the country is essentially the volume that is discharged by offshore Petrobras operations. In 2005, the average total volume of PW discharged offshore on the Brazilian coast was 73 million m 3 /year, representing less than 3% PW discharged onto other oceans worldwide.

Faced with the latest experiences on Brazilian oil spill incidents, Petrobras has been trying to overcome many challenges in environmental management and operational safety, aiming to prevent environmental risks. This paper presents the oil characterizations and monitoring studies in affected ecosystems such as the hot spots on soils affected by the Iguassu River oil spill (occurred in July 2000, due to a pipeline rupture in the scraper area of REPAR, a Petrobras refinery located in the state of Parana), by the Vessel Vergina II oil spill in São Sebastião channel (located in the state of São Paulo, occurred in November 2000) and lastly, the Guanabara Bay oil spill (a pipeline rupture that occurred in January 2000, due to a pipeline rupture between oil terminal and REDUC, a Petrobras refinery located in the state of Rio de Janeiro). Chemical analysis were performed in different sample matrixes including many parameters such as total petroleum hydrocarbons (TPH), aliphatic compounds (n-alkanes), unresolved complex mixtures (UCM), benzene, toluene, ethylbenzene and xylenes (BTEX), polycyclic aromatic hydrocarbons (PAH), terpanes and steranes, that are the parameters usually monitored after a spill oil. Visual inspections were also performed mainly in Guanabara Bay in order to identify the affected ecosystems by the spilled oil and to plot maps of classified regions based on the level of visual oil contamination. The acute toxicity was evaluated in water soluble fraction (WSF) of the spilled oils using ecotoxicological tests.

Part of the production of the Refinery Getúlio Vargas (Paraná State, South Brazil), is transported through OLAPA Pipeline to a Marine Terminal in Paranaguá. In February/2001 occurred a displacement of a great amount of land which caused abrupt rupture of the pipeline in km 57, and 57.000 liters of diesel oil was spilled. Despite all efforts of PETROBRAS contingency team, the oil spilled reached 3 rivers (Meio River, Sagrado River and Nhun-diaquara River) and ending at the sea in Antonina Bay. Right after the incident, a monitoring program was established to evaluate short term effects. One year after the incident, long term effects were also evaluated, especially concerning benthic community and ecotoxicology on the rivers affected by the spill, and plant and birds community in region on its influence. The results point short term effects on water chemistry, but those lasted no more than one week. Short and long term effects on birds and benthic community were not detected.