We derive optimal road fuel taxes for gasoline, diesel and ethanol for Brazil. Fuel-related externalities, including carbon emissions and air pollution, and distance-related externalities, such as accidents, congestion and road damages, are added as Brazil has today no other way to effectively tax these components. A value-added tax (VAT) of 26.5 per cent is added to the tax for gasoline and ethanol, but not for diesel which is mostly an input and not final consumption. On this basis, we find that the optimal gasoline, diesel and ethanol taxes are US$1.03, 0.85 and 0.58 per litre, of which the respective carbon taxes, excluding VAT, are about US$0.14, 0.16 and 0.04 per litre given a carbon price of US$60 per ton of CO2. The largest externality component for gasoline and ethanol is accidents followed by congestion and carbon emissions. For diesel, air pollution is most significant, followed by accidents and congestion.

Bioremediation has been proposed as a means of dealing with oil spills on the continent. However, the introduction of non-native organisms, including microbes, even for this purpose would appear to breach the terms of the Environmental Protocol to the Antarctic Treaty. This study therefore aimed to optimize the growth conditions and diesel degradation activity of the Antarctic native bacteria Arthrobacter spp. strains AQ5-05 and AQ5-06 through the application of a one-factor-at-a-time (OFAT) approach. Both strains were psychrotolerant, with the optimum temperature supporting diesel degradation being 10–15°C. Both strains were also screened for biosurfactant production and biofilm formation. Their diesel degradation potential was assessed using Bushnell–Haas medium supplemented with 0.5% (v/v) diesel as the sole carbon source and determined using both gravimetric and gas chromatography and mass spectrophotometry analysis. Strain AQ5-06 achieved 37.5% diesel degradation, while strain AQ5-05 achieved 34.5% diesel degradation. Both strains produced biosurfactants and showed high biofilm adherence. Strains AQ5-05 and AQ5-06 showed high cellular hydrophobicity rates of 73.0% and 81.5%, respectively, in hexadecane, with somewhat lower values of 60.5% and 70.5%, respectively, in tetrahexadecane. Optimized conditions identified via OFAT increased diesel degradation to 41.0% and 47.5% for strains AQ5-05 and AQ5-06, respectively. Both strains also demonstrated the ability to degrade diesel in the presence of heavy metal co-pollutants. This study therefore confirms the potential use of these cold-tolerant bacterial strains in the biodegradation of diesel-polluted Antarctic soils at low environmental temperatures.

Photocatalytic destruction of the water soluble diesel fraction (WSF) was performed using Cu/TiO2 catalysts. Inexpensive and clean solar light and atmospheric oxygen were used as the energy source and oxidant, respectively. We investigated the effect of Cu species on the formation of a doping energy level between the conduction and valence band in TiO2. Photocatalytic reactions were investigated by monitoring the evolution of WSF as a function oftime of solar irradiation by UV-vis and FTIR spectroscopic techniques. The photocatalytic process in the presence of 5%Cu/TiO2 catalyst, is shown to be quantitatively efficient in the destruction of the water-soluble diesel fraction. The total destruction of water-soluble compounds originating from diesel residues indicates that photocatalysis can be employed for WSF treatment.