OCS Study 

•

MMS 2006-051 

Biodegradation in the Subsurface as 

a Selective Filter for Natural 

Petroleum Emissions 

Final Technical Summary 

Final Study Report 

U.S. Department of the Interior 

Minerals Management Service

Pacific OCS Region 

OCS Study 

MMS 2006-051 

Biodegradation in the Subsurface as 

a Selective Filter for Natural 

Petroleum Emissions 

Final Technical Summary 

Final Study Report 

Authors 

George D. Wardlaw 

Christopher M. Reddy 

Robert K. Nelson 

J. Samuel Arey 

David L. Valentine 

Principal Investigator 

David L. Valentine 

Prepared under MMS Cooperative 

Agreement No. 14-35-0001-31063 

by 

Coastal Marine Institute 

Marine Science Institute 

University of California 

Santa Barbara, CA 93106-6150 

U.S. Department of the Interior 

Minerals Management Service Camarillo

Pacific OCS Region November 2006
Disclaimer 

This report has been reviewed by the Pacific Outer Continental Shelf Region, Minerals Management 

Service, U.S. Department of the Interior and approved for publication. The opinions, findings, 

conclusions, or recommendations in this report are those of the authors, and do not necessarily reflect 

the views and policies of the Minerals Management Service. Mention of trade names or commercial 

products does not constitute an endorsement or recommendation for use. This report has not been 

edited for conformity with Minerals Management Service editorial standards. 

Availability of Report

Extra copies of the report may be obtained from: 

U.S. Dept. of the Interior 

Minerals Management Service 

Pacific OCS Region 

770 Paseo Camarillo 

Camarillo, CA 93010 

Phone: 805-389-7621 

A PDF file of this report is available at: 

http://www.coastalresearchcenter.ucsb.edu/CMI/ 

Suggested Citation 

The suggested citation for this report is: 

Valentine, David L. Biodegradation in the Subsurface as a Selective Filter for Natural Petroleum 

Emissions. MMS OCS Study 2006-051. Coastal Research Center, Marine Science Institute, 

University of California, Santa Barbara, California. MMS Cooperative Agreement Number 14-35-

0001-31063. 35 pages. 
Table of Contents 

FINAL TECHNICAL SUMMARY....................................................................... 1 

FINAL STUDY REPORT...................................................................................... 5 

 Abstract ......................................................................................................... 6 

 Introduction................................................................................................... 6 

 References Cited ........................................................................................... 13 

 Acknowledgements....................................................................................... 16 

 Supplementary Methods................................................................................ 17 

 Appendix 1.................................................................................................... 21 

 Supplemental References.............................................................................. 28 

 

 
List of Tables 

Table S1. Concentrations of major hydrocarbon classes .......................................... 20 

 

 

 

List of Figures 

Figure 1. GCxGC with flame ionization detection (FID) chromatograms .............. 8 

Figure 2. Difference chromatograms ...................................................................... 9 

Figure 3. Cumulative rank-distribution for all hydrocarbons.................................. 10 

Figure 4. Raw chromatograms transformed............................................................ 11 

Figure S1. An image of oil seeping from the sea floor............................................. 17 

Figure S2. A graph of n-alkyl cyclopentanes and cyclohexanes ............................. 19 
Biodegradation in the Subsurface as a Selective Filter 

1

FINAL TECHNICAL SUMMARY 

STUDY TITLE: Weathering of Aromatic Compounds in the Coastal Marine Environment: 

Quantifying Rates of Microbial Metabolism 

REPORT TITLE: Biodegradation in the Subsurface as a Selective Filter for Natural 

Petroleum Emissions 

CONTRACT NUMBER: 14-35-0001-31063 

SPONSORING OCS REGION: Pacific 

APPLICABLE PLANNING AREA(S): Southern California 

FISCAL YEAR(S) OF PROJECT FUNDING: FY 02/03, FY 03/04, FY 04/05 

COMPLETION DATE OF REPORT: November 2006 

COSTS: FY 02-04 – $83,071 

CUMULATIVE PROJECT COST: $83,071 

PROJECT MANAGERS: Russell J. Schmitt

AFFILIATION: Coastal Research Center, Marine Science Institute, University of 

California, Santa Barbara, CA 93106 

ADDRESS: University of California, Santa Barbara, CA 93106 

PRINCIPAL INVESTIGATOR: David L. Valentine 

ADDRESS: Department of Earth Science and Marine Science Institute, University of 

California, Santa Barbara, CA 93106 

KEY WORDS: oil seep, weathering, aromatic hydrocarbons, biodegradation 

BACKGROUND: Several tons of oil seep from the sea floor into the waters of coastal 

California each day. The oil is converted to tar by an ill-defined combination of chemical, 

biological and physical processes – collectively referred to as weathering. The broad focus of 

this project was to determine the microbial role in the weathering process – particularly as it 

relates to aromatic hydrocarbons. 

OBJECTIVES: The objectives of this work were to investigate the nature of hydrocarbon 

weathering processes, particularly those mediated by microbes. 
Final Technical Summary – Valentine 

2

DESCRIPTION: Initially we planned to use a radiotracer approach to investigate the 

consumption of specific aromatic hydrocarbons. Soon after the project was initiated we became 

aware of a new analytical approach better suited to the investigation of microbial hydrocarbon 

weathering: two-dimensional comprehensive gas chromatography (GC×GC). At the same time, 

the instrument we planned to use for the radiotracer work was pulled from the market, 

confirming our decision to switch techniques. 

 

Completed research focused on the detailed compositional changes that occur in petroleum from 

the time of formation, through subsurface migration, to the point of seepage from the seafloor 

and finally to spreading at the sea surface. This was achieved applying the new technique of 

comprehensive two-dimensional gas chromatography to a natural progression of petroleum 

samples collected from subsurface reservoirs, the sea floor and the sea surface. 

STUDY RESULTS: Environmental studies designed to assess the patterns and rates of 

petroleum weathering during migration and seepage has been completed, the samples were 

analyzed using GC×GC, and a manuscript has been submitted for publication. This manuscript 

highlights the power of the approach developed in this study, and shows detailed chemical 

changes in over 4000 specific hydrocarbon compounds. Biodegradation is shown to be the 

dominant process in the subsurface, accounting for a loss about half the total petroleum 

hydrocarbon. Once petroleum reaches the sea floor, evaporative processes act rapidly, causing a 

loss of about 10% of the total petroleum hydrocarbon – on the order of minutes. Other physicalchemical processes, such as adsorption to a thin layer, also seem to drive compositional changes. 

The entire weathering scheme appears to drive the petroleum toward a more even massdistribution of compounds, which may provide a quantitative and robust biodegradation index. 

 With regard to specific compounds and compound classes, striking trends in the chemical 

composition of petroleum are apparent from these studies. During transport from the reservoir to 

the sea surface, a number of compound classes, representing several hundred distinct 

compounds, are removed nearly quantitatively. The compound classes most affected include nalkanes, branched alkanes, isoprenoids, alkyl cyclohexanes, alkyl cyclopentanes, alkyl benzenes, 

and alkyl napthalenes. The application of physical model incorporating evaporation (gas 

washing) and dissolution (water washing) indicates that neither of these processes can explain 

the observed changes in chemical composition – thus indicating these changes are microbial in 

origin. Biomarkers such as hopanes and steranes in these samples remain unchanged. 

Differences are also observed between samples at the sea floor and at the sea surface, though not 

as pronounced as the differences previously discussed. These differences are best explained by 

evaporation, that is, the low boiling-point compounds are preferentially removed. This may 

occur through gas washing at the sea floor or through evaporation at the sea surface. While this 

investigation was geographically limited in scope, focusing on only one seep, the patterns of 

weathering are striking and provide never-before-seen resolution as to the changes in petroleum 

composition due to weathering processes. 
Biodegradation in the Subsurface as a Selective Filter 

3

STUDY PRODUCTS: 

One manuscript has been submitted for publication based on this work, and two presentations 

were recently given. Two additional publications are planned for research resulting in-part from 

MMS support. These include the results of long-running biodegradation studies and a 

comparison study of oil composition from various reservoirs offshore reservoirs. 

Publications: 

American Geophysical Union 2005 Fall Meeting, Wardlaw and Valentine (2005) Petroleum 

Weathering Associated with Hydrocarbon Migration and Seepage, a Case Study From the Santa 

Barbara Channel, CA (published abstract). 

Wardlaw G, C Reddy, B Nelson, S Arey and D Valentine (submitted to Nature) Biodegradation 

in the subsurface a selective filter for natural petroleum emissions. 

Research Presentations:

American Geophysical Union 2005 Fall Meeting, Valentine, Wardlaw, Kinnaman, Redmond, 

Kimball, Busso and Larson (2005) Lessons in Microbial Geochemistry from the Coal Oil Point 

seep field: progess and prospects (published abstract). 
4
Biodegradation in the Subsurface as a Selective Filter 

5

FINAL STUDY REPORT 

Biodegradation in the subsurface as a selective filter for 

natural petroleum emissions 

George D. Wardlaw1

, Christopher M. Reddy2, Robert K. Nelson2, J. Samuel Arey3 & David 

L. Valentine4 

1

Graduate Program in Marine Science, University of California, Santa Barbara, CA 93106, USA

2

Woods Hole Oceanographic Institution, Marine Chemistry and Geochemistry Dept, MS#4, Woods Hole, MA 

02543 USA 

3

Laboratory of Computational and Biological Chemistry, Swiss Federal Institute of Technology Lausanne, 

Switzerland 

4

Department of Earth Science and Marine Science Institute, University of California, Santa Barbara, CA 93106 USA 
Final Study Report - Valentine 

6

Abstract 

Hydrocarbon migration in the deep subsurface is a ubiquitous process in petroleum- and gasproducing regions1,2. Hydrocarbons ineffectively trapped by geologic structures gradually 

migrate to the surface and form areas of intense seepage, with estimated global emissions of 

6×1011 grams per year into the world’s oceans3

. Subsurface petroleum accumulations with 

temperatures below ca. 80 o

C are prone to biodegradation, a process leading to the production of 

heavy oils4 which are of low economic value and are difficult to extract5. Extensive 

quantification of changes in the chemical composition of biodegraded petroleum has been 

elusive due to the long timescales involved6, the heterogeneity of the subsurface and because 

traditional analyses are unable to resolve or quantify many of the constituent hydrocarbons7,8. 

Here we apply the technique of comprehensive two-dimensional gas chromatography (GC×GC) 

to quantify differences in the chemical composition of petroleum hydrocarbons sampled from 

subsurface reservoirs, a proximal seep at the sea floor and the sea surface overlying the seep – all 

within the Coal Oil Point seep field located offshore Goleta, CA9. We show that biodegradation 

in the subsurface has the greatest impact on hydrocarbon composition with greater than 47% (by 

mass) loss of petroleum hydrocarbons including systematic changes in the concentration 

distribution of over 4000 compounds. Evaporation due to gas washing and/or atmospheric 

exposure is found to be significant once petroleum reaches the sea surface. The quantification of 

chemical changes described here provides previously unattainable patterns of metabolic 

preference, and showcases an approach to better quantify the rates and extent of weathering 

processes for complex hydrocarbon mixtures. 

Introduction 

The biodegradation of petroleum hydrocarbons is well established for both aerobic10 and 

anaerobic prokaryotes11-13. The rates and extents of petroleum biodegradation in near-surface 

environments have been measured directly, but establishing activity in the deep subsurface relies 

on inferences including variability in the chemical composition of petroleum1,2,4 and the 

existence of prokaryotes14. Suspected limits on petroleum biodegradation in the subsurface 

include temperature2,5, nutrient availability4

, salinity, phase partitioning and the presence of 

toxins15. Degradation patterns of specific biomarkers have previously been compiled and 

chemical indices have been developed to rank the extent of subsurface petroleum 

biodegradation15,16; still, only a fraction of all petroleum hydrocarbons are typically quantified 

and little is presently known about the metabolic specificity of anaerobic prokaryotes that 

consume petroleum in-situ4. 

 

Most petroleum biodegradation studies typically focus on fewer than a hundred compounds that 

can be identified and quantified by one-dimensional chromatographic techniques11,17. GC×GC 

provides significant advantages over previous approaches, increasing the number of petroleum 

hydrocarbons (in the range of C10-C43) that can be resolved and accurately quantified by greater 

than an order of magnitude6-8. This capability is beneficial when analyzing biodegraded 

petroleum, which typically lacks many of the readily-quantified, and easily degraded, 

components such as n-alkanes8

. 

 
Biodegradation in the Subsurface as a Selective Filter 

7

The Coal Oil Point seep field is an established study site located offshore Goleta, CA3,9. The 

seep field is approximately 18 km2

 in area, is located in water depths ranging from 5 to 100 m 

and is estimated to emit 50 to 170 barrels of oil and 100 to 130 tons of natural gas per day9. The 

geologic structure of the seep field includes a series of crested anticlines formed during folding 

of the Miocene-age Monterey formation, overlain by more recent deposits9. The Monterey 

Formation is believed to serve as both source rock and geologic trap for local petroleum 

deposits9,18. Oil bearing reservoirs embedded within anticlines are located at depths between 

1000 and 1700 m where the ambient temperature ranges between 65-75 oC19. Oil and gas 

migrate upward through fractures in the diatomaceous chert of the Monterey Formation9,18; these 

fractures may also provide a conduit for oxidants, nutrients, and possibly prokaryotes to 

penetrate into the reservoir. Geologic evidence indicates that hydrocarbon seepage occurred in 

this region for at least the past several hundred thousand years with high temporal and spatial 

variability20,21. 

 

The subsurface environment underlying the Coal Oil Point hydrocarbon seeps is presumed 

anoxic, precluding an important role for aerobic metabolism in the subsurface. Several lines of 

evidence support this presumption. Gases and production water collected from the reservoirs 

underlying the seeps contain abundant reduced chemicals such as hydrogen sulphide and ferrous 

iron2. Production waters drawn from the reservoir have been found to harbour populations of 

strictly-anaerobic prokaryotes including methanogens14,19. At the sea floor, seep gas has the 

odour of hydrogen sulphide, is devoid of oxygen and supports active populations of sulphideoxidizing bacteria22 (Supplementary Figure S1). Furthermore, sediments overlying seeps within 

the COP field have been shown to harbour high rates of sulphate reduction22. Given these 

observations and the limited capacity of seawater to deliver oxygen to the subsurface, it seems 

likely that sulphate reduction to sulphide and carbon dioxide reduction to methane serve as 

primary electron accepting processes active in the seep subsurface. 

 

The samples reported here were collected from subsurface oil reservoirs, the sea floor at an 

active seep, and at the sea surface overlying the seep – all from the COP seep field. Three 

samples were collected from the oil reservoir, each from active oil wells accessed by Platform 

Holly. The three wells, 3242-9, 3242-15 and 3242-18 are located at depths of 995 – 1115, 1230 

– 1295, and 1025 – 1235 meters respectively, and are at an ambient temperature of 60-70 o

C. 

Analysis of the three samples using GC×GC indicates a high degree of similarity, and a sample 

from well 3242-15 (34°23.370 N by 119° 53.258 W) was chosen for further comparison. Two 

samples were collected by scuba diver from the sea floor at a location informally known as 

Jackpot Seep (34°24.175 N by 119°52.670 W, 15 m depth). Both samples were collected as they 

oozed from the sea floor through an area of exposed bedrock. Two samples were also collected 

as they reached the sea surface overlying Jackpot Seep; this occurred while the divers collected 

samples at the sea floor. Chromatographic analysis of the four seep samples indicates a high 

degree of similarity within the pairs, and one sample from each set was chosen for further 

comparison. GC×GC chromatograms representative of petroleum from each environment are 

displayed in Figure 1. In addition, a sample of less-degraded reservoir oil was collected from 

outside the seep area (Platform Gail; 16-L, 34°07.500 N by 120°24.020 W, 66 o C; 1740 m) to 

serve as a reference. 

 
Final Study Report - Valentine 

8

Figure 1. GC×GC with flame ionization detection (FID) chromatograms of (a) crude oil from Platform Holly (Well 

#2342-15), (b) crude oil collected as it was emerging from the sea floor at Jackpot Seep, and (c) a droplet of crude 

oil collected as it was spreading on the sea surface above Jackpot Seep. Visual trends represent compound classes 

as are shown on annotated chromatographs found in Nelson et al. 20068

. The C30 bacterially-derived biomarker 

17α,21β(H)-hopane was used to normalize each image. The retention index employed throughout this manuscript is 

the Kovats index29, which is useful for comparing retention between samples analyzed under varying temperature 

programs or between samples analyzed on different chromatographs.

Application of GC×GC to the chosen samples resulted in the quantification of 4626, 4335, and 

4607 distinct hydrocarbon compounds in the reservoir, sea floor and sea surface samples, 

respectively (Figure 1). The reservoir has been moderately biodegraded in-situ, based on the 

scale of Wenger et al (2002)23. Hopane and sterane biomarkers as well as carbon isotope ratios 

of bulk oil (δ13C -23.4 to -22.7 ‰ VPDB) are consistent with petroleum from the Monterey 

formation24. Each sample had similar concentrations of steranes and hopanes, indicating they 

were likely generated from the same source rock; this was consistent with previous results from 

the COP field24. Numerous compounds quantified in the reservoir samples are absent in the sea 

floor and sea surface samples (Supplementary Tables S1 and S2), as shown using difference 

chromatograms (Figure 2)8

. The disappearance of these compounds in the subsurface is not 

consistent with evaporation or dissolution processes; rather, it is attributed primarily to the action 

of anaerobic prokaryotes active in the conduits and reservoirs connecting the source rock to the 

sea floor. 
Biodegradation in the Subsurface as a Selective Filter 

9

Figure 2. Difference chromatograms produced by (a) subtracting the chromatogram of a sea floor sample (Fig. 1b) 

from the chromatogram of a reservoir sample (Fig. 1a) and (b) the chromatogram of a sea surface sample (Fig. 1c) 

from the chromatogram of a sea floor sample (Fig. 1b). The base-plane appears white, while more abundant 

compounds in (a) the reservoir sample and (b) the sea floor sample appear red. More abundant compounds in (a) the 

sea floor sample and (b) the sea surface sample appear blue and compounds with little difference in concentration in 

both samples vanish. These difference chromatograms highlight both the (a) biodegradation of abundant 

hydrocarbons that occurs in the subsurface as well as (b) the physical processes acting to alter the hydrocarbon 

composition of the crude oil from the time it reaches the sea floor until its eventual transit to the sea surface. The 

star shown near the center of the chromatogram denotes the internal standard, dodecadihydrotriphenylene.

Analysis (Figure 3) revealed a trend toward more evenly distributed concentrations of 

compounds as a result of biodegradation. This trend may prove useful as a quantitative 

biodegradation index. The compound classes displaying the highest levels of biodegradation 

between the subsurface and sea floor include many of the components present at high 

concentration, such as n-alkanes, branched/isoprenoid alkanes, alkyl mono-cyclic alkanes, alkyl 

benzenes, and alkyl naphthalenes (Supplementary Tables S1 and S2). n-alkanes and alkylbenzenes, which respectively represent 10.9% and 8.1% of total petroleum hydrocarbons (TPH) 

in the reservoir, were quantitatively consumed. Isoprenoids / branched alkanes and alkyl 

naphthalenes represent 17.5% and 5.2% of TPH in the reservoir and were found to decrease by 

85% and 81%, respectively. n-alkyl cyclopentanes and n-alkyl cyclohexanes together represent 

1.5% of TPH, and were found to decrease by 78%. There is an apparent microbial preference for 

the high molecular weight members of this class (Supplementary Figure S2), with compounds 
Final Study Report - Valentine 

10

containing greater than 20 carbons being quantitatively consumed. Concentrations for a subset 

of over 180 individual compounds are provided in Table S2 of the supplemental on-line 

information. 

 

Figure 3. Cumulative rank-distribution for all hydrocarbons quantified in the reservoir, sea floor and sea surface 

samples. An even distribution of compounds is provided for reference as is a sample of less degraded oil from the 

Monterey formation. Note the log scale. The number of compounds present in each sample was normalized to 100, 

and the concentration of each component is provided in ppm, relative to the sum of TPH in the sample.

GC×GC chromatograms allow for elucidation of quantitative signatures indicative of phase 

transfer to air and water. Patterns of phase transfer are distinguishable because the twodimensional retention time of each GC×GC peak can be uniquely mapped to the volatility and 

aqueous solubility of the corresponding hydrocarbon compound25.

 We find no clear evidence for 

phase transfer in the subsurface, supporting our contention that biodegradation is the responsible 

mass loss process (Figure 4). Based on duplicate samples collected at the sea floor and the sea 

surface, we estimate a 10% TPH mass loss due to evaporation during this transition. The mass 

loss pattern seen in Figure 4 is consistent with evaporation, likely resulting from either gas 

washing at the sea floor or evaporation at the sea surface. Trends suggest that observed phase 

transfer rates of ~ C12 to C15 hydrocarbons are very rapid compared to expected rates based on 

gas-liquid boundary layer considerations. This suggests that spontaneous spreading at an airwater interface may fractionate volatile compounds based on differences in surface tension 

among hydrocarbon constituents. No evidence of aqueous dissolution was found, and this 
Biodegradation in the Subsurface as a Selective Filter 

11

process was not expected to significantly affect TPH composition within the ten to twenty 

seconds that the oil resided on the sea surface during collection. 

Figure 4. Raw chromatograms were transformed to depict the chromatogram distributed with respect to 

hydrocarbon log volatility and hydrocarbon log aqueous solubility. Depicted are (a) the log-transformed reservoir 

sample to sea floor sample ratio and (b) the log-transformed sea floor sample to sea surface sample ratio. Observed 

trends of mass loss and mass gain (normalized to C30 17α,21β(H)-hopane) suggest that: (a) the sea floor sample is 

heavily biodegraded with respect to the reservoir sample, rather than evaporated or aqueously dissolved; (b) the sea 

surface sample is partly evaporated relative to the sea floor sample. Note that the log aqueous solubility assignments 

are only semi-quantitative estimates below values of about –8 (very sparingly soluble) for the n-alkanes series25. 

This did not interfere with any conclusions about water-washing.

This is the first work providing an extensive description of the compounds found in seeping oil 

and the first to differentiate water washing, evaporation and biodegradation. The ability to 

identify and quantify thousands of hydrocarbons in a complex mixture such as crude oil 

represents a significant advance in analytical and environmental chemistry. While many of the 

compounds resolved here remain unidentified, biodegradation patterns can still be determined 
Final Study Report - Valentine 

12

based on retention patterns. Among the as-yet unidentified compounds resolved here, many may 

serve as biomarkers, providing information about the original source of organic carbon, the 

environment of deposition, diagenetic processes, the thermal history of the source rock, and the 

mixing of different oils. For example, we quantified a family of long-chain acyclic and cyclic 

isoprenoid alkanes, which are presumably derived from archaeal tetra-ethers26 (Supplemental 

Table S2). The apparent biodegradation preference for this family is acyclic > dicyclic > 

tricyclic. Structural characterization of these molecules has the potential to differentiate a 

depositional source (marine crenarchaea27) from a post-depositional source (hyperthermophilic 

archaea in the subsurface) and to provide other details on the history of the source rock. 

 

The biodegradation filter as described in this work clearly attenuates the emission of numerous 

hydrocarbons at the COP seep field. While the efficacy of this filter is dependent on factors such 

as the geologic setting and petroleum flux rate, it is apparent from the widespread distribution of 

biodegraded oils that this filter is globally important. Approximately 6×1011 grams of crude oil 

per year is estimated to seep from the subsurface to the sea surface3, 28. Assuming that rates of 

crude oil seepage in terrestrial settings are similar in magnitude and that a 50% loss of 

hydrocarbons is typical, we estimate that greater than 1012 grams per year of hydrocarbons are 

likely degraded prior to the escape of residual crude oil. This is equivalent to an annual 

economic loss of greater than half a billion US dollars. Significantly more than this amount is 

likely biodegraded to such an extent that it becomes trapped permanently in the subsurface. 

Athabasca and Orinoco oil fields, the two largest in the world, are examples of such biodegraded 

accumulations. 
Biodegradation in the Subsurface as a Selective Filter 

13

References Cited 

1. Aitken, C. M., Jones, D. M., & Larter, S. R. Anaerobic hydrocarbon biodegradation in deep 

subsurface oil reservoirs. Nature 431, 291-294 (2004). 

2. Willhelms, A. et al. Biodegradation of oil in uplifted basins prevented by deep-burial 

sterilization. Nature 411, 1034-1037 (2001). 

3. Kvenvolden, K. A. & Cooper, C. K. Natural seepage of crude oil into the marine environment. 

Geo.-Marr. Lett., 23, 140-146 (2003). 

4. Head, I. M., Jones, D. M., & Larter, S. R. Biological activity in the deep subsurface and the 

origin of heavy oil. Nature, 426, 344-352 (2003). 

5. Connan, J. in Advances in Petroleum Geochemistry Vol. 1 (eds Brooks, J & Welte, D. H.) 

299-335 Academic Press, London (1984). 

6. Reddy, C. M. et al. The West Falmouth oil spill after thirty years: the persistence of petroleum 

hydrocarbons in marsh sediments. Environ. Sci. Technol. 36, 4754-4760 (2002). 

7. Frysinger, G. S., Gaines, R. B., Xu, L., & Reddy, C. M. Resolving the unresolved complex 

mixture in petroleum-contaminated sediments. Environ. Sci. Technol. 37, 1653-1662 (2003). 

8. Nelson, R. K. et al. Tracking the weathering of an oil spill with comprehensive twodimensional gas chromatography. Environ. Forensics 7, 1-12 (2006). 

9. Hornafius, J. S., Quigley D., & Luyendyk, B. P. The world's most spectacular marine 

hydrocarbon seeps (Coal Oil Point, Santa Barbara Channel, California): quantification of 

emissions. J. Geophys. Res.-Oceans 104, 20703-20711 (1999). 

10. Atlas, R. M., & Bartha R. Hydrocarbon biodegradation and oil-spill bioremediation. Adv. 

Microb. Ecol. 12, 287-338 (1992). 

11. Spormann, A. M. & Widdel, F. Metabolism of alkylbenzenes, alkanes, and other 

hydrocarbons in anaerobic bacteria. Biodegradation 11, 85-105 (2000). 

12. Coates, J. D., Woodward, J., Allen, J., Philp, P., & Lovley, D. R. Anaerobic degradation of 

polycyclic aromatic hydrocarbons and alkanes in petroleum-contaminated marine harbour 

sediments. Appl. Environ. Microbiol. 63, 3589-3593 (1997). 

13. Rueter, P. et al. Anaerobic oxidation of hydrocarbons in crude-oil by new types of sulfatereducing bacteria. Nature 372, 455-458 (1994).

14. Orphan, V. J., Boles, J., Goffredi, S. K. & DeLong, E. F. Geochemical influence on 

community structure and microbial processes in high temperature oil reservoirs. Geomicrobiol. 

J. 20, 295-311 (2003). 
Final Study Report - Valentine 

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15. Peters, K. K., Walters, C. C. & Moldowan, J. M. in The Biomarker Guide, Biomarkers and 

Isotopes in Petroleum Exploration and Earth History. 2nd Edition. II 646-650, Cambridge 

University Press, Cambridge, MA (2002). 

16. Peters, K. K., Walters, C. C. & Moldowan, J. M. in The Biomarker Guide, Biomarkers and 

Isotopes in the Environment and Human History. 2nd Edition I 198-251, Cambridge University 

Press, Cambridge, MA (2002). 

17. Van Hamme, J. D., Singh, A., & Ward, O. P. Recent advances in petroleum microbiology. 

Microbiol. Mol. Biol. Rev 67, 503-549 (2003) 

18. Reed, W. E. & Kaplan, I. R. The chemistry of marine petroleum seeps. J. Geochem. Explor.

7, 255-293 (1977). 

19. Orphan, V. J., Taylor, L. T. Hafenbradl, D., & DeLong, E. F. Culture-dependent and cultureindependent characterization of microbial assemblages associated with high-temperature 

petroleum reservoirs. Appl. Environ. Microbiol. 66, 700-711 (2000). 

20. Boles, J. R., Eichhubl, P., Garven, G., & Chen, J. Evolution of a hydrocarbon migration 

pathway along basin-bounding faults: evidence from fault cement. AAPG Bull. 88, 947-970 

(2004). 

21. Hill, T.M. et al. Late Quaternary evidence for climatically driven hydrocarbon emissions. (in 

revision at PNAS) (2006). 

22. Bauer, J.E., Montagna, P.A. Spies, R.B. Hardin, D.D. & Prieto M. Microbial 

biogeochemistry and heterotrophy in sediments of a marine hydrocarbon seep. Limnol. 

Oceanogr. 33, 1493-1513 (1988). 

23. Wenger, L. M., Davis, C. L., & Isaksen, G. H. Multiple Controls on Petroleum 

Biodegradation and Impact in Oil Quality. (SPE71450, Society of Petroleum Engineers, 2001). 

24. Hostettler, F. D., Rosenbauer, R. J., Lorenson, T. D., & Dougherty, J. Geochemical 

characterization of tarballs on beaches along the California coast. Part I - shallow seepage 

impacting the Santa Barbara Channel Islands, Santa Cruz, Santa Rosa and San Miguel. Org. 

Geochem. 35, 725-746 (2004). 

25. Arey, S. J., Nelson, R. K., Xu, L., & Reddy, C. M. Using comprehensive two-dimensional 

gas chromatography retention indices to estimate environmental partitioning properties for a 

complete set of diesel fuel hydrocarbons. Anal. Chem. 77, 7172-7182 (2005). 

26. Ventura, G. T. Biomarkers of hydrothermally altered, late Archean metasediments from the 

southern Abitibi subprovince of Ontario, Canada. PhD thesis, Department of Earth and 

Environmental Sciences, University of Illinois at Chicago, (July, 2006). 
Biodegradation in the Subsurface as a Selective Filter 

15

27. DeLong, E. F. et al. Dibiphytanyl ether lipids in nonthermophilic crenarchaeotes. Appl. 

Environ. Microbiol. 64, 1133-1138 (1998). 

28. National Research Council Oil in the Sea: Inputs, Fates and Effects. Washington, D.C.: 

National Academy Press, May. NRC (2003). 

29. Kovats, E. Gas chromatographic characterization of organic substances in the retention index 

system. Advan. Chromatog. 1:229-247 (1965). 
Final Study Report - Valentine 

16

Acknowledgements

We thank S. Horner and Venoco Inc. for providing access to reservoir samples. We also thank J. 

Boles for providing advice on the geologic structure of the COP field. We acknowledge support 

from the US Minerals Management Service (Task 85338 to DLV), the US National Science 

Foundation (OCE-0447395 to DLV and IIS-0430835 to CMR), the California Toxic Substance 

Research and Training Program (19909 to GDW), and the US Department of Energy (DE-FG02-

06ER15775 to CMR). 
Biodegradation in the Subsurface as a Selective Filter 

17

Supplementary Methods 

The hydrocarbon composition of three oil samples collected at the sea surface, on the sea floor, 

and from a production well on Platform Holly were analyzed as the hexane soluble extracts of 

each sample by comprehensive two-dimensional gas chromatography (GC×GC), which can 

separate an order of magnitude more petroleum hydrocarbons than traditional gas 

chromatography (Frysinger et al., 2003; Figure 1). For a more detailed discussion on this 

technology, refer to Reddy et al. (2002). Briefly, the oil samples were dissolved in hexane at a 

concentration of 4 mg/mL, sodium sulphate was added to remove any traces of water. The 

samples were mixed vigorously on a vortex mixer and then allowed to stand overnight. The 

soluble hydrocarbon fraction was decanted into a clean vial and the insoluble material which 

precipitated out of solution (asphaltenes) was discarded. 

Supplementary Figure S1. An image of oil seeping from the sea floor at Jackpot Seep. The white thread-like 

filaments shown here are composed of uncharacterized sulphide-oxidizing bacteria. Scale bar = 1 cm. 

Separation of petroleum hydrocarbons was achieved with a GC×GC system employing an 

Agilent 6890 gas chromatograph configured with a 7683 series split/splitless auto-injector, two 

capillary gas chromatography columns, a model KT-CLM-ZOE02 loop jet modulator (Zoex 

Corporation, Lincoln, NE), and a flame ionization detector. Each reservoir sample was injected 

in splitless mode and the purge vent was opened at 2.5 minutes. The inlet temperature was 

300°C. The first-dimension column and the loop jet modulator reside in the main oven of the 

Agilent 6890 gas chromatograph. The second-dimension column is housed in a smaller oven 
Final Study Report – Valentine 

18

installed on the right side of the main oven. With this configuration, the temperature profiles of 

the first-dimension column, thermal modulator (hot jet), and the second-dimension column can 

be independently programmed. The first-dimension column was a nonpolar 100% dimethyl 

polysiloxane phase (Restek Rtx-1 Crossbond, 6.5m length, 0.10mm I.D., 0.4 μm film thickness) 

that was programmed to remain isothermal at 37°C for 5 minutes and then ramped from 37 to 

307° C at 1.5°C min-1. The modulation loop was deactivated fused silica (1.6m length, 0.10mm 

I.D.). The thermal modulator (hot jet) was heated to 100°C above the temperature in the main 

oven to insure that all trapped compounds were thoroughly and rapidly desorbed from the cold 

spot. Second-dimension separations were performed on a 50% phenyl polysilphenylene-siloxane 

column (SGE BPX50, 0.8m length, 0.10mm I.D., 0.1 μm film thickness) that was programmed 

to remain isothermal at 70°C for 5 minutes and then ramped from 70 to 340°C at 1.5°C min-1. 

The thermal modulator loop pulse frequency was 10 seconds (0.10 Hz), and the pulse width was 

300 milliseconds. The cold jet gas was dry N2 chilled with liquid Argon at a flow rate of 4.0 L 

min-1. The carrier gas was H2 at a constant flow rate of 1.5 mL min-1. The FID signal was 

sampled at 100 Hz. Peaks were identified with commercially available standards from Aldrich 

Chemical, National Institute of Standards and Technology (NIST), and Chiron. 

Dodecadihydrotriphenylene was used as an internal standard and eluted at 92.4 minutes on the xaxis and at 5.7 seconds on the y-axis (Figure 1 and Figure 2). 
Biodegradation in the Subsurface as a Selective Filter 

19

Supplemental Figure S2. A graph of (a) n-alkyl cyclopentanes and (b) n-alkyl cyclohexanes containing various 

numbers of carbons, versus concentration. The pattern of compound loss between the reservoir and sea floor, 

particularly for compounds greater than 20 carbons in size, indicates a preference for these compounds by in-situ

microbes. The preferential loss of low-carbon-number compounds between the sea floor and sea surface is 

attributed to evaporation.

The GC×GC FID data was processed with GC Image software (GC Image, LLC, Lincoln NE; 

Reichenbach et al., 2003; 2004). Each GC×GC image was base-plane subtracted to remove the 

FID offset (Reichenbach et al., 2003). Peak volumes of the resolved components in each of the 

GC×GC images were measured with the GC Image software. In order to set the threshold peak 

detection values in the GC Image software, the data in each GC×GC chromatogram was visually 

inspected in tabular form (spreadsheet) as well as in colour contour plots (plan view) and three 

dimensional surface rendering (mountain plots) formats. The peak detection filter was set to 

exclude all peaks which where one-half the volume or less than the smallest peak detected 
Final Study Report – Valentine 

20

visually in any of the chromatograms. Using these settings, we detected between 4,000 and 

5,000 components in each chromatogram. Peaks representing less than 0.02 ng of material did 

not meet our peak detection criteria and were excluded from our analysis. 

Supplementary Table S1. Concentrations of major hydrocarbon classes.

Reservoir Sea floor Sea Surface 

(μg/mg)* (μg/mg)* (μg/mg)* 

Total petroleum hydrocarbons 338 181 203 

alkanes 164 59.6 52.8 

branched and isoprenoid alkanes 59.0 9.20 11.0 

normal alkanes 36.8 0.00 0.00 

n-alkyl cyclohexanes 2.30 0.60 0.50 

n-alkyl cyclopentanes 2.60 0.50 0.40 

alkyl benzenes 27.4 0.00 0.00 

naphthalenes 17.7 13.9 20.7 

phenanthrenes 7.90 10.1 6.70 

*Concentration is in micrograms compound per mg of oil analyzed. 
Biodegradation in the Subs

21

Appendix 1 

Compound Reservoira Sea floorb Sea-Surfacec % loss  (ng/mg) (ng/mg) (ng/mg) Reservoir to SC12 n-alkyl cyclohexane 198 98.3 39.2 50.4 C13 n-alkyl cyclohexane 201 143 43.3 28.7 

C14 n-alkyl cyclohexane 135 93.0 58.3 30.8 C15 n-alkyl cyclohexane 134 66.4 90.9 50.4 C16 n-alkyl cyclohexane 118 74.1 104 37.0 C17 n-alkyl cyclohexane 143 49.3 44.8 65.4 C18 n-alkyl cyclohexane 120 23.3 51.4 80.5 C19 n-alkyl cyclohexane 122 23.8 57.5 80.4 

C20 n-alkyl cyclohexane 109 22.1 27.7 79.7 

C21 n-alkyl cyclohexane 106 0 0 100 C22 n-alkyl cyclohexane 131 0 0 100 C23 n-alkyl cyclohexane 101 0 0 100 C24 n-alkyl cyclohexane 105 0 0 100 C25 n-alkyl cyclohexane 85.3 0 0 100 C26 n-alkyl cyclohexane 67.0 0 0 100 C27 n-alkyl cyclohexane 60.0 0 0 100 C28 n-alkyl cyclohexane 61.8 0 0 100 C29 n-alkyl cyclohexane 70.8 0 0 100 C30 n-alkyl cyclohexane 47.3 0 0 100 C31 n-alkyl cyclohexane 69.5 0 0 100 C32 n-alkyl cyclohexane 49.8 0 0 100 C33 n-alkyl cyclohexane 42.1 0 0 100 C34 n-alkyl cyclohexane 28.7 0 0 100 C35 n-alkyl cyclohexane 25.6 0 0 100 C12 n-alkyl cyclopentane 291 117 40.2 59.8 C13 n-alkyl cyclopentane 189 132 41.3 29.8 
Final Study Report – Valentine 

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C14 n-alkyl cyclopentane 170 59.5 67.5 65.1 

C15 n-alkyl cyclopentane 173 62.4 83.2 64.0 C16 n-alkyl cyclopentane 153 40.0 46.4 73.8 C17 n-alkyl cyclopentane 128 28.5 19.2 77.8 C18 n-alkyl cyclopentane 104 19.6 26.8 81.1 C19 n-alkyl cyclopentane 102 22.6 19.8 77.8 C20 n-alkyl cyclopentane 102 24.5 29.5 75.9 C21 n-alkyl cyclopentane 111 0 0 100 C22 n-alkyl cyclopentane 111 0 0 100 C23 n-alkyl cyclopentane 91.4 0 0 100 C24 n-alkyl cyclopentane 91.2 0 0 100 C25 n-alkyl cyclopentane 107 0 0 100 C26 n-alkyl cyclopentane 123 0 0 100 C27 n-alkyl cyclopentane 94.4 0 0 100 C28 n-alkyl cyclopentane 119 0 0 100 C29 n-alkyl cyclopentane 77.6 0 0 100 C30 n-alkyl cyclopentane 82.9 0 0 100 

C31 n-alkyl cyclopentane 63.7 0 0 100 

C32 n-alkyl cyclopentane 48.1 0 0 100 C33 n-alkyl cyclopentane 38.6 0 0 100 C34 n-alkyl cyclopentane 36.6 0 0 100 C35 n-alkyl cyclopentane 36.1 0 0 100 ααα(S)C27 cholestane 189 114 145 39.8 

αββ(R)C27 cholestane 203 185 200 9.2 

αββ(S)C27 cholestane 192 181 215 5.8 

ααα(R)C27 cholestane 233 162 193 30.5 ααα (S) C28 ergostane 166 126 140 24.0 αββ(R)C28 ergostane 269 174 245 35.4 

αββ(S)C28 ergostane 180 175 175 3.0 

ααα(R)C28 ergostane 215 141 196 34.4 
Biodegradation in the Subs

23

ααα(S)C29 stigmastane 157 101 133 36.1 αββ(R)C29 stigmastane 230 134 195 41.7 αββ(S)C29 stigmastane 134 115 132 14.7 ααα(R)C29 stigmastane 153 134 159 12.5 28,30-bisnorhopane 360 409 403 -13.4 norhopane 223 288 164 -29.2 C30 hopane 214 183 221 14.3 

31S homohopane 138 131 123 5.1 31R homohopane 116 97.8 101 15.4 32S homohopane 129 142 107 -10.3 32R homohopane 91.8 117 90.5 -27.4 33S homohopane 93.7 126 107 -34.3 33R homohopane 108 92.0 91.4 14.5 34S homohopane 99.3 91.8 63.1 7.5 34R homohopane 93.0 68.5 51.6 26.4 35S homohopane 119 143 102 -20.0 35R homohopane 81.5 93.8 71.1 -15.1 gammacerane 70.7 53.6 47.6 24.2 farnesane 1.41x10^3 159 165 88.8 norpristane 1.57x10^3 111 133 93.0 pristane 1.71x10^3 84.5 116 95.0 phytane 2.19x10^3 130 227 94.1 cyclic isoprenoid alkane 01 257 48.5 65.0 81.1 cyclic isoprenoid alkane 02 190 41.1 68.7 78.3 cyclic isoprenoid alkane 03 93.6 35.3 32.7 62.2 cyclic isoprenoid alkane 04 114 18.6 24.7 83.6 cyclic isoprenoid alkane 05 217 23.4 25.2 89.2 cyclic isoprenoid alkane 06 288 41.4 56.8 85.6 cyclic isoprenoid alkane 07 371 85.5 116 77.0 
Final Study Report – Valentine 

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(biphytane) cyclic isoprenoid alkane 08 108 22.7 32.4 79.0 monocyclic isoprenoidal alkane 01 - 46.1 47.9 - monocyclic isoprenoidal alkane 02 - 29.3 41.1 - monocyclic isoprenoidal alkane 03 - 42.2 49.4 - monocyclic isoprenoidal alkane 04 - 34.7 40.6 - dicyclic isoprenoidal alkane 01 42.2 34.2 44.1 18.9 dicyclic isoprenoidal alkane 02 53.1 35.8 61.2 32.5 dicyclic isoprenoidal alkane 03 55.9 39.2 48.7 29.9 dicyclic isoprenoidal alkane 04 57.4 27.0 30.0 53.0 dicyclic isoprenoidal alkane 05 69.6 28.4 62.1 59.2 dicyclic isoprenoidal alkane 06 117 45.2 66.7 61.3 dicyclic isoprenoidal alkane 07 33.2 24.7 34.8 25.7 tricyclic isoprenoidal alkane 01 47.2 40.7 62.1 13.7 tricyclic isoprenoidal alkane 02 65.0 59.0 67.3 9.2 tricyclic isoprenoidal alkane 03 53.4 44.9 61.9 16.0 tricyclic isoprenoidal alkane 04 47.3 41.1 45.5 13.0 tricyclic isoprenoidal alkane 05 38.0 20.6 26.8 45.8 tricyclic isoprenoidal alkane 06 74.5 50.3 65.7 32.6 tricyclic isoprenoidal alkane 07 36.0 23.7 39.5 34.1 tricyclic isoprenoidal alkane 08 63.3 40.5 66.1 36.1 tricyclic isoprenoidal alkane 09 55.6 42.9 52.4 22.8 tricyclic isoprenoidal alkane 10 45.4 39.0 48.5 14.0 tricyclic isoprenoidal alkane 11 49.6 40.8 52.5 17.8 tricyclic isoprenoidal alkane 12 34.5 33.9 42.3 1.6 n-C10 1.73x10^3 0 0 100 
Biodegradation in the Subs

25

n-C11 1.78x10^3 0 0 100 

n-C12 1.86x10^3 0 0 100 n-C13 2.05x10^3 0 0 100 n-C14 2.18x10^3 0 0 100 n-C15 2.32x10^3 0 0 100 n-C16 2.24x10^3 0 0 100 n-C17 2.12x10^3 0 0 100 n-C18 2.22x10^3 0 0 100 n-C19 1.94x10^3 0 0 100 n-C20 2.07x10^3 0 0 100 n-C21 1.81x10^3 0 0 100 n-C22 1.83x10^3 0 0 100 n-C23 1.58x10^3 0 0 100 n-C24 1.51x10^3 0 0 100 n-C25 1.13x10^3 0 0 100 n-C26 1.01x10^3 0 0 100 n-C27 879 0 0 100 n-C28 742 0 0 100 n-C29 652 0 0 100 n-C30 594 0 0 100 n-C31 519 0 0 100 n-C32 415 0 0 100 n-C33 321 0 0 100 n-C34 261 0 0 100 n-C35 216 0 0 100 n-C36 197 0 0 100 n-C37 201 0 0 100 n-C38 173 0 0 100 n-C39 75.8 0 0 100 
Final Study Report – Valentine 

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n-C40 60.1 0 0 100 

n-C41 34.3 0 0 100 n-C42 35.7 0 0 100 n-C43 32.2 0 0 100 indan 386 104 71.8 73.2 tetralin 148 104 119 29.8 C14 linear alkyl benzene 28.5 0 0 100 

C15 linear alkyl benzene 33.3 0 0 100 C16 linear alkyl benzene 50.3 0 0 100 C17 linear alkyl benzene 52.4 0 0 100 C18 linear alkyl benzene 65.4 0 0 100 C19 linear alkyl benzene 75.9 0 0 100 C20 linear alkyl benzene 93.8 0 0 100 

C21 linear alkyl benzene 79.9 0 0 100 

C22 linear alkyl benzene 84.1 0 0 100 C23 linear alkyl benzene 78.5 0 0 100 C24 linear alkyl benzene 92.2 0 0 100 C25 linear alkyl benzene 85.7 0 0 100 C26 linear alkyl benzene 100 0 0 100 C27 linear alkyl benzene 53.6 0 0 100 C28 linear alkyl benzene 58.8 0 0 100 C29 linear alkyl benzene 61.2 0 0 100 C30 linear alkyl benzene 65.6 0 0 100 C31 linear alkyl benzene 41.4 0 0 100 C32 linear alkyl benzene 28.9 0 0 100 C33 linear alkyl benzene 33.1 0 0 100 C34 linear alkyl benzene 26.6 0 0 100 C35 linear alkyl benzene 20.7 0 0 100 
Biodegradation in the Subs

27

C36 linear alkyl benzene 21.9 0 0 100 

C37 linear alkyl benzene 17.0 0 0 100 C38 linear alkyl benzene 12.7 0 0 100 

C39 linear alkyl benzene 20.4 0 0 100 

C40 linear alkyl benzene 23.2 0 0 100 naphthalene 179 4.4 4.2 97.5 2-methylnaphthalene 460 45.9 28.3 90.0 1-methylnaphthalene 300 26.6 15.7 91.1 biphenyl 24.6 3.5 85.8 1-ethylnaphthalene 76.3 21.3 14.3 72.0 2,6-dimethylnapthalene 354 96.4 72.8 acenaphthene 10.1 7.0 4.6 30.8 fluorene 101 27.7 61.4 72.5 phenanthrene 66.5 25.6 31.5 61.5 1-methylphenanthrene 51.7 25.9 23.4 49.8 

ddodecadyhydrotriphenylene 629 623 617 

a Reservoir sample from Platform Holly Well 3242-15. b Sediment surface sample from Jackpot seep. c Sea surface sample collected overlying Jackpot see. 

d. Dodecadihydrotriphenylene was used as the internal standard. 
Final Study Report – Valentine 

28

Supplemental References 

1. Reddy, C. M. et al. The West Falmouth oil spill after thirty years: the persistence of petroleum 

hydrocarbons in marsh sediments. Environ. Sci. Technol. 36, 4754-4760 (2002). 

2. Frysinger, G. S., Gaines, R. B., Xu, L., & Reddy, C. M., Resolving the unresolved complex 

mixture in petroleum-contaminated sediments. Environ. Sci. Technol. 37, 1653-1662 (2003). 

3. Reichenbach, S. E., Ni, M. T., Kottapalli, V., & Visvanathan, A. Information technologies for 

comprehensive two-dimensional gas chromatography. Chemom. Intell. Lab. Syst. 71, 107-120 

(2004). 

4. Reichenbach, S. E., Ni, M. T., Zhang, D. M., & Ledford E. B., Image background removal in 

comprehensive two-dimensional gas chromatography. J. Chromatogr. A 985: 47-56 (2005). 
29

The Department of the Interior Mission

As the Nation's principal conservation agency, the Department of the Interior has responsibility for most 

of our nationally owned public lands and natural resources. This includes fostering sound use of our 

land and water resources; protecting our fish, wildlife, and biological diversity; preserving the 

environmental and cultural values of our national parks and historical places; and providing for the 

enjoyment of life through outdoor recreation. The Department assesses our energy and mineral 

resources and works to ensure that their development is in the best interests of all our people by 

encouraging stewardship and citizen participation in their care. The Department also has a major 

responsibility for American Indian reservation communities and for people who live in island territories 

under U.S. administration. 

The Minerals Management Service Mission 

As a bureau of the Department of the Interior, the Minerals Management Service's (MMS) primary 

responsibilities are to manage the mineral resources located on the Nation's Outer Continental Shelf 

(OCS), collect revenue from the Federal OCS and onshore Federal and Indian lands, and distribute 

those revenues. 

Moreover, in working to meet its responsibilities, the Offshore Minerals Management Program

administers the OCS competitive leasing program and oversees the safe and environmentally sound 

exploration and production of our Nation's offshore natural gas, oil and other mineral resources. The 

MMS Royalty Management Program meets its responsibilities by ensuring the efficient, timely and 

accurate collection and disbursement of revenue from mineral leasing and production due to Indian 

tribes and allottees, States and the U.S. Treasury. 

The MMS strives to fulfill its responsibilities through the general guiding principles of: (1) being 

responsive to the public's concerns and interests by maintaining a dialogue with all potentially affected 

parties and (2) carrying out its programs with an emphasis on working to enhance the quality of life for 

all Americans by lending MMS assistance and expertise to economic development and environmental 

protection.