Removal and Fate of Chlorinated Solvents from Contaminated Groundwater

Transcription

1 Removal and Fate of Chlorinated Solvents from Contaminated Groundwater Joel G. Burken, Associate Professor Department of Civil, Architectural & Environmental Engineering University of Missouri-Rolla

2 Acknowledgments: Co-authors Xingmao Ma, UMR Garrett Struckhoff, UMR John Schumacher, USGS - Rolla Bill Schneider, Roy F.Weston

3 Outline Experimental Diffusion and Fate Modeling Full-Scale Systems Conclusions (implications)

4 Hybrid poplars grown in the laboratory in sand, hydroponically, or in soil Dosed with TCE Diffusion traps placed on stems At completion all aboveseptum tissues analyzed Laboratory Studies

5 Diffusion Trap Needle Activated Carbon Air Flow Glass Tubing Teflon seal Poplar cutting

6 Diffusion Trap Analysis Collected TCE, mg Upper Diffusion Trap Lower Diffusion Trap Days TCE dosing at 550 ppm until day 28 n = 2, S.D. shown.

7 Total diffusion mass vs. influent TCE Captured, mg Upper Diffusion Traps Lower Diffusion Traps y = 0.015x R 2 = 0.99 y = 0.007x R 2 = Feed Concentration, ppm Accumulative Diffusion mass, 28 day dose period

8 Diffusion varied with height, and transpiration rate TCE diffusion mg Tree #1 Tree #2 Tree #3 Trap 1 Trap 2 Trap 3 Trap 4 Grown in Sand, Dose concentration = 440 ppm

9 Mass vs Height Height cm TCE in transpiration stream, ppm

10 Modeling approach J(z+ z) C i-1, Q r Degradation dz Adsorption Diffusion z C i, Q C(r,z) V dc dt i = CiQ Ci 1 Q dn i J(z)

11 Model equations Proof of concept, thin layer diffusion Based on geometric mean V dc dt i = CiQ Ci 1 Q dn i C = C 0 e ra ( R r a Dπ )* z Q N i = C o Qe 2r z2 adπ z Q( R ra ) z1

12 Modeling: Biomass TCE vs. Height 10 TCE in transpiration streams, ppm Height cm Diffusion Coefficient =2 x 10-6 cm 2 /s, TSCF= 0.2 (C o also measured)

13 Modeling: Diffusion vs. Height TCE diffusion mg Measured Modeling Height cm

14 Field Sampling Collect a core sample of the trunk/stem Core sample placed into headspace vial After equilibration time headspace is analyzed via GC Partition coefficients are used to determine initial concentrations Field-scale Diffusion traps installed Aberdeen Proving Ground, Edgewood, MD

15 Collected Cores and Spatially

16 Vertical Sampling to Subsurface

17 Concentration in Biomass vs. height Core height (m) TCE in tree core (ug/g)

18 Spatial analysis of core TCE concentrations w/ groundwater

19 Diffusion at Field Site Diffusion samplers similar to labscale, using tedlar & portable pumps. 3 Methods in 3 Labs Filtered effluent air through Act. Carbon GC (hours) Static SPME GC/MS (10 min) Summa Canisters GC/MS (2 l)

20 Diffusion Trap Sampling Tree # Carbon Tube (µg) SPME (ng)* Summa (ppbv)** gum * Data courtesy of John Schneider, Lou Martino; Argonne Nat Labs ** Data courtesy of John Wrobel-DoD; Steve Hirsch, Scott Fredrickson-EPA 46

21 SPME Analysis CHCl3 TCE TeCA GC ECD blank Tree 62 BKG 7/11 BKG 7/10 Tree 175 Tree 67 Tree 181 7/11 Tree 181 7/10 SPME analysis by John Schneider, Argonne National Labs

22 Conclusions Chlorinated VOCs are translocated from contaminated plumes Tree Cores can provide quantitative information for groundwater concentrations (not absolute) Mass removal relates to ET rates, C GW Diffusion to the atmosphere is a dominant fate

23 Riverfront Superfund Site John Schumacher, USGS Rolla LARGE DOD CONTRACT FOR TENTS 1950S-1970s U.S. Environmental Protection Agency, Region VII U.S. Geological Survey USGS science for a changing world

24 W1 OU-1 Missouri River FOUR OPERABLE UNITS W2 W4 OU-4 OU-1 (Riverfront Site) Former Al pole swaging PCE used and dumped MO State Highway 100 OU-2 W3 OU-3 OU-2 (Kellwood Site) Tube mill PCE used and dumped OU-3 (Old City dunp) MILE OU-4 (East New Haven) PCE in creeks USGS science for a changing world

25 OU1 RIVERFRONT SITE Tree core recon. Missouri River 30 feet alluvium GW feet Dry cleaner %U%U Lagoon 60 Trees cored 7 Residences PCE in 29 trees 0.1 7,600 ug/l Screen out - Dry cleaner - Bulk tank area - Old Auto dealer W FT USGS science for a changing world

26 Wl 17.1 Sg 240 Ch 240 Br, Sm <1 Mb 11.3 Pc 58 Pc 72 Bx 1.2

27 OU1 RIVERFRONT SITE well installation Based on tree-cores: %U - 17 Direct-push holes %U %U - 7 alluvial wells %U %U - GW ft deep %U %U %U %U %U %U %U %U %U %U W1

28 Acknowledgments National Science Foundation (BES ) U.S. Department of Ag. ( ) US EPA National Risk Management Lab (R ) Lockheed Martin Environmental Research Center UMR Steve Hirsh, Scott Fredrickson, Harry Compton (EPA), Bill Schneider (R.F.Weston), John Wrobel, Amy Burgess (Dept. Army), John Schneider, Lou Martino (Argonne Labs), Chris Gussman (Lockheed-Martin).