Surface soil pollution in a medium-size American city and its rural surroundings

1. Surface soil pollution in a medium-size American city and its rural surroundings Johan Liebens Department of Environmental Studies Carl J. Mohrherr and K. Ranga Rao Center for Environmental Diagnostics and Bioremediation University of West Florida

2. Introduction • Soils in urban areas often polluted. • Naples, Seville, Beijing, Bangkok, . . . • How about pollution in smaller cities? • Pensacola (Florida)

3. X Pensacola

4. Introduction • Soils in urban areas often polluted. • Naples, Seville, Beijing, Bangkok, . . . • How about pollution in smaller cities? • Pensacola area has many water, sediment, air pollution problems. • Surface soils in Pensacola and surrounding areas polluted?

5. Background City of Pensacola • "America's first settlement" • 52,000 inhabitants • 100 km2 • 4 Superfund sites Escambia County • 300,000 inhabitants • 9th worst in USA in total environmental releases • 16th in air releases • 2nd in underground injection

6. Objectives • Assess pollution of dioxins/furans and polycyclic aromatic hydrocarbons (PAHs) in surface soils in and around Pensacola. • Assess heavy metal pollution in surface soils in public places in and around Pensacola. • pollution levels • urban vs. rural • influence traffic • spatial distribution • potential origin

7. Sampling sites 125 public places in and around Pensacola • include parks, playgrounds, sports facilities • selected public places in urban areas (Pensacola and Milton) • all public places outside urban areas • other places accessible to public in central part of study area • All samples analyzed for heavy metals • 25 of 125 samples analyzed for dioxins/furans and PAHs

9. AL GA MS Pensacola FL study area Gulf of Mexico Gulf of Mexico

10. Description of dioxins/furans dioxin • Dibenzodioxins • 2 benzene rings + 2 oxygen bridges • Dibenzofurans • 1 oxygen bridge and 1 carbon-carbon bond • 210 congeners • Byproduct • 17 congeners are toxic • Cause chloracne, cancer, . . . • chicken and pigs in Belgium, Pres. Yuschenko

11. Description of PAHs • ≥ 2 benzene rings • multiple compounds • Source: petroleum, combustion • Sediment quality guidelines for 13 PAHs • Seven carcinogenic, some cause birth defects

12. Definition of heavy metal • ? • High atomic weight and/or high density • 40 to 80 elements • trace metal, toxic metal • Cd, Cr, Cu, Pb, Hg, Ni, Zn • As • Natural sources, anthropogenic • mining, metallurgy, fossil fuels, pesticides, . . . • Some beneficial in small amounts, others toxic • respiratory problems, liver, kidney, nerve damage, cancer (Hg), . . .

13. Results Dioxins/furans and PAHs

14. ResultsDioxins/furans, PAHs • Calculated total toxic equivalent (TEQ) • TEQ is a measure for overall toxicity/carcinogenicity • multiply concentration x WHO toxicity factor • add products for all congeners • Compared to: • US EPA screening level for children (dioxin/furan TEQ) • FL DEP residential soil cleanup target level (both) • FL DEP industrial/commercial soil cleanup target level (PAH TEQ)

15. Dioxin/furan TEQ previous studies TEQ[ppt]

16. Dioxin/furan TEQ this study

17. Gulf of Mexico

18. PAH TEQ previous studies

19. PAH TEQ this study

21. Results summary for dioxins/furans and PAHs • Dioxin/furan TEQs do not exceed screening level. • PAH TEQs exceed residential and industrial/commercial SCTL in former industrial area only. • TEQs much lower elsewhere in the two counties, including urban areas. • TEQs comparable to other areas of similar land use.

22. Results Heavy metals 1. Pollution levels

23. Heavy metal concentrations RSCTL = Residential Soil Cleanup Target Level

26. Heavy metal pollution • Index of geoaccumulation: • Igeo = log2 (Conc. sample/1.5*Conc. background) • < 0 unpolluted, 0 - 2 polluted, > 2 strongly polluted • Enrichment factor: • EF = (Conc. metal/Conc. Al)sample / (Conc. metal/Conc. Al)background • < 2 unpolluted, 2 - 10 polluted, > 10 strongly polluted

27. background

28. Comparison of general and local background concentrations [mg/kg]

29. Proportion [%] of "strongly polluted" sites

31. Results Heavy metals 2. Influence of land use

32. Average trace metal concentrations [mg/kg] Values in red are statistically significant (P < 3%)

34. Average trace metal concentrations [mg/kg] Values in red are statistically significant (P < 3%)

35. Factor loading plot Metals plotting in the same part of the graph are of common origin.

36. Pearson correlation coefficients between soil properties and metal concentrations Values in red are statistically significant (P < 5%)

37. Results Trace metals 3. Influence of traffic

38. Average standardized metal concentration vs. distance from road (n=19)

39. Results Heavy metals 4. Spatial distribution

40. What does spatial pattern tell us about origin? Hot Spot Analysis • Determines if sites with high values tend to cluster spatially. • Assigns a sampling site to a hot spot if values of site and surrounding sites are high. • "High" values identified by statistical comparison with whole dataset. • Output is Z score. • Run on Pollution Load Index (PLI) which is geomean of sample/background concentration for all metals.

42. Conclusions • Dioxin/furan TEQ, PAH TEQ highest in industrial corridor. • "Strong" heavy metal pollution at very few sites. • Arsenic exceeds RSCTL at sites throughout study area. • Pb has significantly higher concentrations in urban areas: Anthropogenic origin. • Cr and Ni originate from parent material. • Heavy metal hotspot in Palafox industrial corridor. • Influence of this small city (Pensacola) on heavy metal content of surface soils is limited beyond the immediate vicinity of industrial areas and major roads.

43. Acknowledgements • USEPA cooperative agreement X-97455002. • Student assistants: Eric Joyner, Kristal Walsh, Michael Somerville.

44. Thank you! Questions?