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The use of passive samplers to monitor effectiveness of AC - - PowerPoint PPT Presentation

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The use of passive samplers to monitor effectiveness of AC amendment to contaminated sediments Amy M.P. Oen, Elisabeth M.L. Janssen, Gerard Cornelissen, Gijs D. Breedveld, Espen Eek and Richard G. Luthy NORDROCS 2012 Oslo, Norway 18-21

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SLIDE 1

The use of passive samplers to monitor effectiveness of AC amendment to contaminated sediments

Amy M.P. Oen, Elisabeth M.L. Janssen, Gerard Cornelissen, Gijs D. Breedveld, Espen Eek and Richard G. Luthy

NORDROCS 2012 Oslo, Norway 18-21 September 2012

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SLIDE 2

Traditional methods to determine vertical pore water profiles of HOCs

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SLIDE 3

Field Site at mudflat in San Francisco Bay

South Basin

Cho et al. 2009 (ES&T, 43, 3815–3823)

San Francisco South Basin Hunters Point Naval Shipyard

  • Hunters Point site
  • Activated carbon amendment to sequester PCBs
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SLIDE 4

Passive samplers and PRCs

  • Sediment-penetrating sampling rods (40 cm)
  • Polyoxymethlyene (POM, 17 mm thick)
  • Polyethylene (PE, 51 mm thick)
  • Performance reference compounds (PRCs)
  • Tri

(PCB 29)

  • Tetra (PCB 69)
  • Penta (PCB 103)
  • Hexa (PCB 155)
  • Hepta (PCB 192)
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SLIDE 5

Deployment: August 2008

  • pictures
  • 5 rods POM
  • 2 rods PE
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SLIDE 6

Retrieval time series

  • POM: 14, 26, 57, 100 and 154 days
  • PE: 57 and 154 days
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SLIDE 7

1 2 3 4 5 6 3 5 8 10 13 15

TOC (%) Depth (cm)

Vertical distribution of AC amendment

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SLIDE 8

Calculating pore water concentrations

  • Assuming equilibrium has been achieved

sampler passive sampler passive water pore

K C C

_ _ _

Knowledge of passive sampler-water partition coefficient Measurement of PCB in passive sampler

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SLIDE 9

PCB uptake in POM over the time series

Measurements indicate equilibrium has been achieved

1 2 3 4 50 100 150 200

Cpom (ng/mg) Deployment exposure time (days)

0-2.5 cm, TOC=2.9% 13.5-19 cm, TOC=4.5% 30-35.5 cm, TOC=1.9% Oen et al. 2011 (ES&T, DOI :10.1021/es200174v)

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SLIDE 10

PRC depletion behavior at t = 154 days

50 100

PRC reduction in PE (%)

PCB29 PCB 69 PCB 103 PCB 155 PCB 192

50 100 0-2.5 2.5-8 8-13.5 13.5-19 19-24.5 24.5-30 30-35.5 35.5-41

PRC reduction in POM (%)

Location of POM (cm from surface)

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SLIDE 11

PCB uptake in PE over the time series

Measurements support earlier investigations and approach to equilibrium is slow and

  • ngoing

1 2 3 4 50 100 150 200

Cpe (ng/mg) Deployment exposure time (days)

0-2.5 cm, TOC=2.9% 13.5-19 cm, TOC=4.5% 30-35.5 cm, TOC=1.9% Oen et al. 2011 (ES&T, DOI :10.1021/es200174v)

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SLIDE 12

Calculating pore water concentrations

  • Including depletion of PRCs

Knowledge of passive sampler-water partition coefficient Measurement of PCB in passive sampler

 

 

t k K C C

e sampler passive sampler passive water pore

     exp 1

_ _ _

Calculated exchange rate coefficient

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SLIDE 13

5 10 15 20 25 30 35 40 45 4 8 12

Location of passive sampler (cm from surface) Cpw (ng/l)

5 10 15 20 25 30 35 40 45 4 8 12

Cpw (ng/l)

5 10 15 20 25 30 35 40 45 4 8 12

Cpw (ng/l)

(a) (b) (c)

Vertical pore water distributions

POM - equilibrium PE – PRC depletion POM – PRC depletion Variations within a factor of two, reasonable for in-situ measurements

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SLIDE 14

Vertical pore water distributions

POM - equilibrium PE – PRC depletion POM – PRC depletion

5 10 15 20 25 30 35 40 45 4 8 12

Location of passive sampler (cm from surface) Cpw (ng/l)

5 10 15 20 25 30 35 40 45 4 8 12

Cpw (ng/l)

5 10 15 20 25 30 35 40 45 4 8 12

Cpw (ng/l)

(a) (b) (c)

Sensitivity analysis for Kpom values, ± 0.3 log units

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SLIDE 15

5 10 15 20 25 30 35 40 45 4 8 12

Location of passive sampler (cm from surface) Cpw (ng/l)

5 10 15 20 25 30 35 40 45 4 8 12

Cpw (ng/l)

5 10 15 20 25 30 35 40 45 4 8 12

Cpw (ng/l)

(a) (b) (c)

Vertical pore water distributions

POM - equilibrium PE – PRC depletion POM – PRC depletion 2-4 % AC 1 % AC Deeper layers have traces

  • f AC amendment
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SLIDE 16

AC amendment performance - modelling

Hale 2009 (Ph.D. Dissertation, Newcastle University)

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SLIDE 17

AC amendment performance – measurements compared to model

Tomaszewski and Luthy 2008 (ES&T, 42, 6086–6091)

In earlier study, measurements in top 15 cm (PE) showed 60% reduction in PCBs 18 months post AC-amendment Minimally mixed Well mixed

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SLIDE 18

AC amendment performance - measurements compared to model

In this study, measurements in top 15 cm (PE) showed 80% reduction in PCBs 30 months post AC-amendment Minimally mixed Well mixed

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SLIDE 19

Conclusions and application

  • Vertical pore water profiles
  • good agreement among measurement and

calculation methods

  • variations within a factor of two
  • In-situ measurement of pore water concentrations
  • more representative of field conditions
  • particularly for AC-amended sediments as

traditional measurement methods probably underestimate actual pore water concentrations

  • Passive sampling approach is a robust and promising

method for site monitoring and remedial treatment evaluation

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SLIDE 20

Acknowledgements