Studies of the vertical distribution of134Cs,137Cs,238Pu,239, 240Pu,241Pu,241Am and210Pb in ombrogenous mires at mid-latitudes

Mitchell, P.I.; Schell, W.R.; McGarry, A.T.; Ryan, Tom; Sanchez-Cabeza, Joan-Albert; Vidal‐Quadras, A.

doi:10.1007/bf02038351

Cited by 32 publications

(8 citation statements)

References 23 publications

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“…The peat accumulation rate, calculated using the constant initial concentration (CIC) model of Appleby and Oldfield (1992), was found to be 0.15 kg m −2 yr −1 (equivalent to a growth rate of 0.12 cm yr −1 ) for this part of the sequence. This value is within previously observed ranges for peat accumulation at these latitudes (Clymo 1991;Mitchell et al 1992;Tolonen et al 1992).…”

Section: Analysis Of 214 Bi and 214supporting

confidence: 91%

“…Our data are consistent with this observation in that limited down-core movement of 137 Cs is apparent, with measurable concentrations present at levels well below the first detected occurrence of 241 Am. On the other hand, it is recognized that 241 Am is less mobile in peat than 137 Cs (McGarry 1991;Mitchell et al 1992). Thus, it is reasonable to regard the 241 Am peak as a reliable horizon marker, approximating to the year 1964, when maximal fallout from weapons testing occurred (Testa et al 1999).…”

Section: Radionuclide Profilesmentioning

confidence: 99%

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A Recent History of ¹⁴C, ¹³⁷Cs, ²¹⁰Pb, and ²⁴¹Am Accumulation at Two Irish Peat Bog Sites: an East Versus West Coast Comparison

2001

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Data on radiocarbon (14C), 137Cs, 210Pb, and 241Am levels in an ombrotrophic peat sequence from a montane site on the east coast of Ireland are compared with data from a similar sequence at an Atlantic peatland site on the west coast. The 14C profiles from the west and east coasts show a broadly similar pattern. Levels increase from 100 pMC or less in the deepest horizons examined, to peak values at the west and east coast sites of 117 ± 0.6 pMC and 132 ± 0.7 pMC, respectively (corresponding to maximal fallout from nuclear weapons testing around 1964), thereafter diminishing to levels of 110–113 pMC near the surface. Significantly, peak levels at the east coast site are considerably higher than corresponding levels at the west coast site, though both are lower than reported peak values for continental regions. The possibility of significant 14C enrichment at the east coast site due to past discharges from nuclear installations in the UK seems unlikely. The 210Pbex inventory at the east coast site (6500 Bq m−2) is significantly higher than at the west coast (5300 Bq m−2) and is consistent with the difference in rainfall at the two sites. Finally, 137Cs and 241Am inventories at the east coast site also exceed those at the west coast site by similar proportions (east:west ratio of approximately 1:1.2).

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Section: Analysis Of 214 Bi and 214supporting

confidence: 91%

Section: Radionuclide Profilesmentioning

confidence: 99%

A Recent History of ¹⁴C, ¹³⁷Cs, ²¹⁰Pb, and ²⁴¹Am Accumulation at Two Irish Peat Bog Sites: an East Versus West Coast Comparison

2001

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“…The differences in the 210 Pb‐activity of the surface moss layers and total 210 Pb burden in hollows and hummocks suggest that there must be differential deposition and/or post‐depositional Pb mobility in some microhabitat types [ Damman , 1978; Oldfield et al , 1979; Pakarinen et al , 1983; Urban et al , 1990; Oldfield et al , 1995]. However, several studies have concluded that Pb remains immobile after deposition on a peat surface [e.g., Livett et al , 1979; Mitchell et al , 1992; Appleby et al , 1997; Vile et al , 1999]. In this study, evidence of possible Pb mobility was also found in three hollows that showed exceptionally high 210 Pb‐activity in the surface moss layers, suggesting post‐depositional mobility from hummock to hollow or from depth to the surface.…”

Section: Discussionmentioning

confidence: 99%

Nitrogen deposition and increased carbon accumulation in ombrotrophic peatlands in eastern Canada

Turunen

Roulet

Moore

et al. 2004

Global Biogeochemical Cycles

155

121

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[1] Recent and long-term accumulation rates of carbon (C), using 210 Pb-and 14 C-dating, were examined in 23 ombrotrophic peatlands in eastern Canada, where average 1990-1996 atmospheric wet nitrogen (N) deposition ranged from 0.3 to 0.8 g N m À2 yr À1 . The average recent rate of C accumulation (RERCA) over the past 150 years was 73 ± 17 (SD) g C m À2 yr À1 , ranging from 40 to 117 g C m À2 yr À1. The difference in RERCA between hummocks (78 g C m À2 yr À1 ) and hollows (65 g C m À2 yr À1 ) was significant. Increased RERCA over the past 50 years was found in hummocks and hollows in regions of higher N deposition and related to both elevated N deposition and growing degree-days above +5°C. There was a statistically significant positive relationship between N deposition alone and present-day C accumulation in both hummocks and hollows (R 2 = 0.28 and 0.38, respectively). Recent N accumulation was significantly larger in high N deposition regions. The total average aboveground vegetation biomass of hollows and hummocks did not differ significantly with N deposition. However, a significantly larger vascular plant leaf biomass was found in both hollows and hummocks of the high N deposition class than in the low N deposition class (>0.6 and <0.4 g m À2 yr À1, respectively). The average long-term apparent rate of C accumulation (LORCA) at 15 sites was 19 ± 8 (SD) g C m À2 yr À1, with no significant difference due to age of peat inception, latitude, or continentality.

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“…The data for plutonium show a typical weapons fallout profile with a sharp rising edge (approximating to the late 1950s), a maximum in the mid-1960s, followed by a gradual decrease up to the present day. The 238 Pu: 239,240 Pu ratios also suggest that the source of this input is from weapons fallout because the 238 Pu: 239,240 Pu ratio for Sellafield derived effluent is typically almost a factor of 10 higher ( , ). The mean 238 Pu: 239,240 Pu ratio (0.028 ± 0.008) is consistent with the well-established fallout ratio at this latitude () once an account is taken of the decay of 238 Pu (T 1/2 = 87.7 y); this is taken as evidence that the plutonium source term does not include detectable input from Windscale/Sellafield.…”

Section: Resultsmentioning

confidence: 99%

Retrospective Search for Evidence of the 1957 Windscale Fire in NE Ireland Using ¹²⁹I and Other Long-Lived Nuclides

Gallagher

McGee

Mitchell

et al. 2005

Environ. Sci. Technol.

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The accident at Windscale in October 1957 resulted in the release to the atmosphere of a large quantity of radioactivity. The presented work is a retrospective search for evidence of contamination from the accident in the northeastern region of Ireland. A lake yielding a high-resolution sedimentary record was identified near the northeast coast of Ireland. This site was used to reconstruct the history of radionuclide input to the region, based on the analysis of a set of cores extracted from the lake. A chronology for sediment accumulation within the lake was established using radioisotopic dating techniques (including 270Pb). High-resolution gamma and alpha spectrometry techniques were used to quantify concentrations of 137Cs, 239,240Pu and 241Am, all of which were released during the accident. The primary radioactive component of the release was 131I (T1/2 = 8 days), but this short-lived isotope has long since decayed. However, 129I (T1/2 = 1.57 x 10(7) years) was also released during the accident, and in a known ratio to 131I. Recent advances in accelerator mass spectrometry now make it feasible to measure 129I at ultra-trace level and thereby retrospectively reconstruct 131I deposition. Clearly resolved concentration profiles for 137Cs, 239,240Pu and 241Am in the lake cores reflect known historical fallout trends. The data suggest that any contamination from the Windscale fire that might have reached this catchment has been overwritten by input from the testing of nuclear weapons in the atmosphere. A time-series for 129I in lake sediment shows that concentrations in recent sediments are approximately 10 times greater than concentrations recorded in strata corresponding to the period of maximum fallout of other radionuclides from atmospheric testing of nuclear weapons (1964). These recent increases in 129I are attributed to increased emissions from the nuclear industry. The study yields no evidence of any enhancement in radioisotope concentrations, over and above global fallout, in strata dated to 1957, and we conclude that contamination from the Windscale fire had negligible impact on the northeastern region of Ireland.

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Studies of the vertical distribution of134Cs,137Cs,238Pu,239, 240Pu,241Pu,241Am and210Pb in ombrogenous mires at mid-latitudes

Cited by 32 publications

References 23 publications

A Recent History of ¹⁴C, ¹³⁷Cs, ²¹⁰Pb, and ²⁴¹Am Accumulation at Two Irish Peat Bog Sites: an East Versus West Coast Comparison

A Recent History of ¹⁴C, ¹³⁷Cs, ²¹⁰Pb, and ²⁴¹Am Accumulation at Two Irish Peat Bog Sites: an East Versus West Coast Comparison

Nitrogen deposition and increased carbon accumulation in ombrotrophic peatlands in eastern Canada

Retrospective Search for Evidence of the 1957 Windscale Fire in NE Ireland Using ¹²⁹I and Other Long-Lived Nuclides

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Studies of the vertical distribution of134Cs,137Cs,238Pu,239, 240Pu,241Pu,241Am and210Pb in ombrogenous mires at mid-latitudes

Cited by 32 publications

References 23 publications

A Recent History of 14C, 137Cs, 210Pb, and 241Am Accumulation at Two Irish Peat Bog Sites: an East Versus West Coast Comparison

A Recent History of 14C, 137Cs, 210Pb, and 241Am Accumulation at Two Irish Peat Bog Sites: an East Versus West Coast Comparison

Nitrogen deposition and increased carbon accumulation in ombrotrophic peatlands in eastern Canada

Retrospective Search for Evidence of the 1957 Windscale Fire in NE Ireland Using 129I and Other Long-Lived Nuclides

Contact Info

Product

Resources

About

A Recent History of ¹⁴C, ¹³⁷Cs, ²¹⁰Pb, and ²⁴¹Am Accumulation at Two Irish Peat Bog Sites: an East Versus West Coast Comparison

A Recent History of ¹⁴C, ¹³⁷Cs, ²¹⁰Pb, and ²⁴¹Am Accumulation at Two Irish Peat Bog Sites: an East Versus West Coast Comparison

Retrospective Search for Evidence of the 1957 Windscale Fire in NE Ireland Using ¹²⁹I and Other Long-Lived Nuclides