Figure 1. World primary energy production by source from 1970 to 1999 (Energy Information Administration, 2001).

Figure 2. World crude-oil production from leading producers, 1960–2000, in million barrels per day (Energy Information Administration, 2001).

Figure 3. Modes of contamination by petroleum products during production, transport, use, and disposal (after Fetter, 1993).

Figure 4. Petroleum products and uses (Energy Information Administration, 1999).

Figure 5. Common products obtained from crude-oil distillation and cracking, and their boiling point range (afterNational Research Council, 1985).

Figure 6. A sample of volatile hydrocarbons present in crude oil for the major compound classes, n-alkanes, isoalkanes, n-alkenes, cycloalkanes, aromatics, and cycloaromatics (after Tissot and Welte, 1984).

Figure 7. Modes of exposure to hydrocarbon contaminants (after Kostecki and Calabrese, 1991).

Figure 8. Simulated contributing areas to a shallow and moderate-depth monitoring and public-supply well (after Kauffman et al., 2001).

Figure 9. Aerobic toluene degradation pathway by (a) aromatic ring attack by dioxygenation and (b) side-chain attack by stepwise oxidation (after Smith, 1990).

Figure 10. Alkane degradation under aerobic conditions, showing incorporation of oxygen from molecular oxygen into the aliphatic compound, producing a fatty acid. Fatty acids are oxidized further by β-oxidation. [H] indicates reducing equivalents that are either required or formed in the reaction step (after Bouwer and Zehnder (1993).

Figure 11. A demonstrated pathway for MTBE biodegradation under aerobic conditions (after Deeb et al., 2000).

Figure 12. Proposed pathways of anaerobic degradation of toluene, ethylbenzene, and o-xylene by the fumarate addition pathway (after Elshahed et al., 2001).

Figure 13. Concentration profiles for groundwater at the Galloway Township gasoline study site in July 1990 and April 1991(after Cozzarelli et al., 1999). The two shallow samples are within the sandy sediments (3.26 m and 3.81 m bls) and one deeper sample (at 4.72 m bls) is within the low-permeability clay-rich layer.

Figure 14. Microbial and chemical profiles from the crude-oil-contaminated aquifer near Bemidji, Minnesota. Methanogenic zones are shaded grey (after Bekins et al., 2002).

Figure 15. Potential indicators of in situ metabolism of toluene and xylene under anaerobic conditions (after Beller, 2000).

United States and world energy consumption by source (January 2000)

Source: Edwards (2001). BBOE=billion barrels of oil equivalent.

Average composition of hydrocarbons in normal producible crude oils (% by weight of hydrocarbon) (total samples—517)

After Tissot and Welte (1984).

Estimated composition of VOC emissions from gasoline evaporation at ambient air temperature

Source: Friedrich and Obermeier (1999).

Pathways relevant to the phase transfer of compounds from petroleum product sources to environmental compartments by partition processes

Solubilities and other properties of select petroleum hydrocarbons and fuel additives

The Henry coefficient is obtained from the solubility and vapor pressure data from this table as follows: H_k=(w_kp/RT)/C_sol. Other values are provided in Table 6.

Composition of a gasoline oxygenated with MTBE and associated equilibrium concentrations in water

Vapor pressure of petroleum compounds as a function of temperature ln(p/p₀)=A−B/(T+273.15) where A=[(0.5035)ΔH]/(T₀+273.15) and B=(0.5035)ΔH

Henry's Coefficient of MTBE and monoaromatic hydrocarbons as a function of temperature ln(H_k/H_k0)=A−B/T where A=[(0.5035)ΔH_Henry]/(T₀+273.15) and B=(0.5035)ΔH_Henry

Theoretical stoichiometry and energetics of mineralization of aromatic and aliphatic hydrocarbons under a range of redox conditions

After Spormann and Widdel (2000). Notes on compounds: Free energy formation (ΔG_f⁰, in kJ mol⁻¹) of hydrocarbons used in the presented equations: C₆H₅(CH₃), toluene (lq): +114.2; C₆H₁₄, hexane (lq): −3.8; C₈H₁₈, octane (lq): +6.41. Free energy formation (ΔG_f⁰, in kJ mol⁻¹) of iron oxides used in the presented equations: Fe(OH)₃, ferric hydroxide (amorphous), −699; α-FeO(OH), goethite (crystalline): −488.6. For adequate comparison of the free energetics of the indicated reactions, ΔG⁰-values have to be related to the same number of electrons transferred, Hence, the values for denitrification and iron(III) reduction must be multiplied by 1.6 and 8, respectively, resulting in free energy changes per 8 mol electrons (viz. per 1.6 mol NO₃⁻ and 8 mol Fe, respectively).