PAH Distribution and Trends in SF Estuary Sediments (1993-2001)

1. Polycyclic Aromatic Hydrocarbons in the San Francisco Estuary Distributions, Trends, and Sources in Sediments (1993-2001) Daniel R. Oros and John R.M. Ross San Francisco Estuary Institute 7770 Pardee Lane, Oakland, CA 94621

2. 9-Year Synthesis 1993-2001: PAH Series Oros and Ross. PAH in SF Estuary sediments. Marine Chemistry 86:169-184, 2004. Ross and Oros. PAH in the in SF Estuary water column. Submitted to Chemosphere Oros and Ross. PAH in SF Estuary bivalves. Submitted to Marine Environmental Research

3. Why are PAH of concern? • Genotoxic • Mutagenic • Carcinogenic • Ubiquitous • Constant input (limited or no control of non-point sources) • Regional Board’s Section 303(d) “Watch” List

4. How do PAH enter the estuary? Combustion of Refined Petroleum Products Vehicular Traffic Trains Industrial Emissions Ferries Fishing and Commercial Vessels

5. Natural and Intentional Burning of Biomass Fuels Fireplaces Campfires Natural Fires

6. Uncontrolled and Accidental Input of Unburned Petroleum and its Refined Products Asphalt and Lube Oil Spills (e.g., crude oil) Creosote Treated Pier Pilings

7. 60,000 gallon diesel spill at Suisun Marsh April 27, 2004. Concern: Toxicity depending on exposure and dosage Diesel fate: dispersion, evaporation, and biodegradation. Photo credit: Kurt Rogers, San Francisco Chronicle

8. Objective • Examine PAH in sediments to determine: • Spatial distributions • Temporal trends • Sources

9. Figure 1. Map of sediment sampling stations (1993-2001)

10. Methods: Spatial Distributions • 25 PAH were summed (PAH) for each station • PAH concentrations were normalized to TOC content (significant relationship) • Stations were grouped into 5 segments: Delta, North Estuary, Central Bay, South Bay, and Extreme South Bay • Comparisons between segments, seasons, and stations were conducted using the non-parametric Kruskal-Wallis test

11. Results: Spatial Distributions Figure 2. Mean PAH distributions by segment • Central Bay and South Bay PAH were significantly higher than North Estuary, Extreme South Bay, and Delta • South and Central Bays were not significantly different • Delta was significantly lower than all other segments

12. Methods: Temporal Trends • PAH concentrations were first normalized to TOC and % fines content by multiple linear regression analysis • Trends for PAH were examined for each station by linear regression analysis using the ln(rescaled residual) as the dependent variable and sampling date as independent variable • A significant positive slope (p<0.05) indicated an increase, a significant negative slope a decrease, and a lack of significance no detectable trend in PAH at a station over time

13. Results: Temporal Trends (1993-2001) • Station Analysis • A statistically significant (p<0.05) decreasing trend in PAH was found only at San Pablo Bay (1 of 26 stations) • No trends were detected at any other stations, which suggests that PAH levels remained constant over the 9 year period • Seasonal Analysis • Sacramento River and Oyster Point showed significantly higher PAH in the wet season than the dry season. No significant seasonal differences were found at other stations

14. Methods: Sources • PAH isomer pair ratios were used as diagnostic indicators to identify possible sources. Isomers have similar partitioning behavior and solubility. Anthracene / Anthracene + Phenanthrene Benz[a]anthracene / Benz[a]anthracene + Chrysene Fluoranthene / Fluoranthene + Pyrene Indeno[1,2,3-c,d]pyrene / Indeno[1,2,3-c,d]pyrene + Benzo[g,h,i]perylene

15. Table 1. PAH isomer pair ratios of specific sources

16. Methods (cont’d): Sources • Bar plots of PAH isomer pair ratios were generated to show estimated frequency (%) of PAH from the various sources in each segment • PAH isomer pair ratios determined from estuary were compared to PAH isomer pair ratios from known environmental, petroleum, and single-source combustion sources compiled from the scientific literature by Yunker et al. (2002)

17. Frequency (%) Estuary Segment Figure 3. Bar plots showing frequency (%) of PAH from various sources in each segment

18. Frequency (%) Estuary Segment Figure 3 (cont’d). Bar plots showing frequency (%) of PAH from various sources in each segment

19. Summary and Conclusions • Mean PAH was significantly higher in the Central and South Bays compared to the North Estuary, Extreme South Bay and Delta. Delta was significantly lower than all others • Distribution could reflect the large amount of urbanized area that surrounds Central and South Bays and the less urbanized area in the Delta

20. Summary and Conclusions (cont’d) • A significant decreasing trend in PAH levels was found at San Pablo Bay • PAH decreasing trend is consistent with previous observations that San Pablo Bay is eroding due to diminished sediment supply and as currents and waves transport sediment from the bay (Jaffe et al., 1998, USGS) • No trends were found at any other stations • Estuary PAH levels remained constant, which is consistent with other national studies that reported no increasing or decreasing trends for PAH

21. Summary and Conclusions (cont’d) • Sacramento River and Oyster Point showed significantly higher PAH in the wet season than the dry season. No significant seasonal differences at other stations • Location near freshwater discharges and estuary margins is an important determinant of PAH sediment concentration

22. Summary and Conclusions (cont’d) • PAH sources were identified by PAH isomer pair ratio analyses using values compiled by Yunker et al. (2002) • Petroleum and Fossil Fuel Combustion • gasoline, diesel, crude oil, and coal (e.g., coal from historical use) • Biomass Burning • wood, wood soot, and grasses • Unburned Petroleum • shale oil, lube oil, and creosote • (e.g., shale oil from refined Monterey oil)

23. Acknowledgements This study was funded by the RMP as a contribution to the 9-Year Synthesis Laboratory Analyses, Field Work and Data Management Dr. Robert Risebrough (Bodega Bay Institute) Dr. Jose Sericano (GERG, Texas A&M) Dr. Francois Rodigari (EBMUD & BACWA) Genine Scelfo (UCSC) Capt. Gordon Smith (RV David Johnston) Applied Marine Sciences Sarah Lowe (SFEI) Cristina Grosso (SFEI) Scientific Peer-Review SFEI Staff Three “Unknown” Reviewers