Soil Dioxin and PAH Study Urban and Rural Study Area Results

Transcription

1 Soil Dioxin and PAH Study Urban and Rural Study Area Results By Roger McGinnis, Ph.D. Hart Crowser and Charles San Juan, LHG, Ecology Toxics Cleanup Program

2 Study Objectives Quantify ambient soil dioxin, and PAH concentrations in both rural and urban environments. Compare dioxin results to Ecology 1999 fertilizer study

3 Sample Locations Rural Soil samples from WA state parks. Urban Soil samples from Seattle neighborhoods with varying land uses.

4 Rural Background Study Park Locations

5 Rural Background Study 41 Soils Samples Collected from 32 State Parks Location criteria Low traffic density Low population density No recent wildfires Not logged Samples collected from undisturbed areas

6 Rural Background Study 5-point composite Depth 0-3 inches Open and forested areas Extraneous matter removed from samples Analysis Dioxins PAHs Arsenic Total organic carbon

7 Laboratory Multi-Increment Subsampling (MIS) Procedure Air dried Sieved through 2 mm (No. 10) sieve Sample spread in a shallow gridded pan Subsample collected from each grid and placed in clean jar Entire contents of jar extracted for analysis

8 Rural Soil Dioxin TEQ

9 Soil dioxin TEQ Forested - Median = 1.3 ng/kg - Maximum = 9.1 ng/kg Open Area - Median = 0.44 ng/kg - Maximum = 2.3 ng/kg

10 Rural Background Dioxin TEQ Summary Adjusted for ½ Detection Limits Parameter Value n 41 Min ng/kg Mean 1.69 ng/kg Median ng/kg Max 9.36 ng/kg 90 th Percentile 4.03 ng/kg 4 x 50 th 2.32 ng/kg 90 th Percentile (Fertilizer Study, 1999) 5.2 ng/kg

11 Rural Background Dioxin TEQ Comparison of substitution and Kaplan-Meier procedure for non-detected congeners

12 Rural Background cpah TEQ Summary Adjusted for ½ Detection Limits Parameter Value n 41 Min Mean Median Max mg/kg mg/kg mg/kg mg/kg 90 th Percentile mg/kg 4 x 50 th mg/kg

13 Rural Soil Arsenic Comparison

14 Soil cpah TEQ Forested - Median = 2.3 ug/kg - Maximum = 24 ug/kg Open Area - Median = 0.53 ug/kg - Maximum = 3.9 ug/kg

15 Soil Arsenic No significant difference between open and forested areas

16 Statewide Rural Study Summary Soil dioxin TEQ Range = ng/kg 90th percentile = 4.03 ng/kg Soil cpah TEQ Range = mg/kg 90th percentile = mg/kg. Arsenic Range = mg/kg 90th percentile = 8.96 (average = 3.72 mg/kg).

17 Urban Soil Dioxin and PAH Study Cooperative effort between Ecology and City of Seattle Objective quantify range and magnitude of urban soil dioxin and PAH levels. Initial key question how does the South Park area (i.e. T-117 site) soil dioxin levels compare to other urban areas?

18 Urban Soil Sampling Study Design Collect 20 soil samples from residential areas in each of 6 Seattle-area neighborhoods Each neighborhood divided into quadrants with approximately equal numbers of residential parcels Randomly collect samples from each study quadrant.

19 Urban Study Design Samples collected from City of Seattle right-ofway (median between road and sidewalk) Sample locations not identified Extraneous material removed from samples Laboratory MIS subsampling procedure used

20 Urban Study Location Criteria Grass strip must be > 2.5 ft. wide No evidence of recent excavation or digging No flower beds, gardens, etc No non-soil material (bricks, ash, wood, glass, etc.) present No staining or dead grass present No parked cars, etc.

21 Urban Soil Dioxin TEQ

22 Urban Soil Dioxin TEQ Summary Adjusted for ½ Detection Limits Parameter Value n 120 Distribution Min Mean Median Max lognormal 1.66 ng/kg 19.1 ng/kg 11.7 ng/kg 115 ng/kg 90 th Percentile 40.9 ng/kg 4 x 50 th Percentile 46.8 ng/kg

23 Urban vs. Rural Soil Dioxin TEQ

24 Urban and Rural Area Dioxin Relative Ratios Relative Fraction Urban Rural ,3,7,8-TCDD 1,2,3,7,8-PeCDD 1,2,3,4,7,8-HxCDD 1,2,3,6,7,8-HxCDD 1,2,3,7,8,9-HxCDD 1,2,3,4,6,7,8-HpCDD OCDD 2,3,7,8-TCDF 1,2,3,7,8-PeCDF 2,3,4,7,8-PeCDF Congener 1,2,3,4,7,8-HxCDF 1,2,3,6,7,8-HxCDF 1,2,3,7,8,9-HxCDF 2,3,4,6,7,8-HxCDF 1,2,3,4,6,7,8-HpCDF 1,2,3,4,7,8,9-HpCDF OCDF

25 Urban Soil cpah TEQ

26 Urban Soil cpah Summary Adjusted for ½ Detection Limits Parameter Value n 120 Min Mean Median Max mg/kg 0.26 mg/kg mg/kg 8.9 mg/kg 90 th Percentile 0.39 mg/kg 4 x 50 th Percentile 1.56 mg/kg

27 Urban Study Summary 120 soil samples from 6 Seattle area neighborhoods. Soil dioxin TEQ Range = ng/kg 90th percentile = 46 ng/kg Soil cpah TEQ Range = mg/kg 90th percentile = 0.39 mg/kg.

28 Questions?