Metal and hydrocarbon behavior in sediments from Brazilian shallow waters drilling activities using nonaqueous drilling fluids (NAFs)

• Published in: Environmental monitoring and assessment 2010-08, Vol.167 (1-4), p.33-47
• Main Authors: Peralba, Maria do Carmo R, Pozebon, Dirce, dos Santos, João H. Z, Maia, Sandra M, Pizzolato, Tânia M, Cioccari, Giovani, Barrionuevo, Simone
• Format: Article
• Language: English
• Subjects: Aluminum; Analysis; Anthropogenic factors; Aromatic hydrocarbons; Atmospheric Protection/Air Quality Control/Air Pollution; Brazil; Cadmium; Chromium; Copper; Cruises; Drilling; Drilling fluids; Earth and Environmental Science; Ecology; Ecotoxicology; Environment; Environmental Management; Environmental monitoring; Environmental Monitoring - methods; Extraction and Processing Industry; Fluids; Geologic Sediments - analysis; Hydrocarbons; Investigations; Iron; Laboratories; Marine sediment; Metals; Metals - analysis; Mineral oils; Monitoring/Environmental Analysis; NAFs; Nickel; Offshore drilling; Oil and gas exploration; Petroleum; Pollution; Polynuclear aromatic hydrocarbons; Sediments; Shallow water; Studies; Toxicity; Water Pollutants - analysis
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-010-1516-2

The impact of drilling oil activities in the Brazilian Bonito Field/Campos Basin (Rio de Janeiro) shell drilling (300 m) using nonaqueous fluids (NAFs) was investigated with respect to Al, Fe, Mn, Ba, Co, Pb, Cu, As, Hg, Cr, Ni, Zn, Cd, V, and aliphatic and polynuclear aromatic hydrocarbons concentrations in the sediment. Sampling took place in three different times during approximately 33 months. For the metals Al, As, Co, Cr, Cu, Cd, Fe, Ni, Mn, V, and Zn, no significant variation was observed after drilling activities in most of the stations. However, an increase was found in Ba concentration—due to the drilling activity—without return to the levels found 22 months after drilling. High Ba contents was already detected prior to well drilling, probably due to drilling activities in other wells nearby. Hydrocarbon contents also suggest previous anthropogenic activities. Aliphatic hydrocarbon contents were in the range usually reported in other drilling sites. The same behavior was observed in the case of polyaromatic hydrocarbons. Nevertheless, the n-alkane concentration increased sharply after drilling, returning almost to predrilling levels 22 months after drilling activities.