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CEP/RMP Sediment Coring Study Update. RMP CFWG, May 2007. Objectives (this Study). Better constrain future loads from eroding buried contaminants Estimate historic loadings of contaminants (especially recent decades)
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CEP/RMP Sediment Coring Study Update RMP CFWG, May 2007
Objectives (this Study) • Better constrain future loads from eroding buried contaminants • Estimate historic loadings of contaminants (especially recent decades) • Characterize contamination with depth to assess current status and likely future changes • Provide data for parameterization and/or evaluation of the multi-box model
Core Sampling Strategy • 17 Cores budgeted • Hybrid (random + deterministic) • 6 samples specifically to understand loading history (wetland deposition zones) • 11 sites to begin representative characterization of Bay sediments • Bay sites vibracore + manual push core, wetlands manually cored (Livingstone)
Distribution of Sites • 3 sites Central Bay, 2 sites each other segments • Preference to RMP repeat stations • CB001S, CB002S, CB006S, • LSB001S, LSB002S, • SB001S, SB002S, • SPB001S, SPB002S, • SU001S, SU002S
Analyses to date • ~10 sections/core for 1+ core per segment • Sections from 30 & 60cm in other core each segment
Results: Suisun • Eroded? – no Cs or Pb profile
Results: San Pablo • Eroding? – Pb and Cs max at top 10cm
Results: Central • Cs and Pb well mixed top 5-10cm • Pb ~4x diff (40 yrs) in 30cm, Cs ~0 >40cm
Results: South • Deposition&Erosion? Well mixed top 10cm • Pb ~4x in 20cm, CS ~0 >20cm • Pb decay and Cs surface max disagree?
Results: Lower South • Deposition? Pb & Cs well mixed top 10cm • Pb ~4x decrease ~30cm, Cs subsurface mixed
Summary • Lead and cesium signals more or less agree for most sites so far • 40-60 years = 30 cm horizon • Top layers highest in Cs many sites • Expect 1960s highest, surface max = static or eroded Bay surface at these sites • Redistributed Cs from eroding sites?