Calculation and uncertainty analysis of 210Pb dates for PIRLA project lake sediment cores

Binford, Michael W.

doi:10.1007/bf00219461

Cited by 558 publications

(306 citation statements)

References 14 publications

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“…Age at depth was estimated using the constant rate of supply (CRS) model (Binford 1990). The unsupported 210 Pb fraction was estimated using three different scenarios: (1) supported 210 Pb ϭ 9 Bq kg Ϫ1 (lowest measured 226 Ra and 210 Pb activities), (2) supported 210 Pb ϭ 14 Bq kg Ϫ1 (highest measured 226 Ra activity), and (3) supported 210 Pb proportional to 226 Ra at each depth (with linear extrapolation for depths where 226 Ra activity was not measured).…”

Section: Resultsmentioning

confidence: 99%

A modern isotope record of changes in water and carbon budgets in a groundwater‐fed lake: Blue Lake, South Australia

Herczeg

Leaney

Dighton

et al. 2003

Limnology & Oceanography

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Groundwater is often a major component of lake water and chemical balances. Alteration in catchment subsurface water balances through land-use change and pumping can affect lake biogeochemical cycles through changes in groundwater flow rates. We present a modern (ϳ200 yr) sediment isotope record (␦ 18 O carb , ␦ 13 C carb , and ␦ 13 C org ) of changes to the water and carbon budget of Blue Lake, which is situated in karstic limestone in South Australia and is mostly fed by groundwater. The 3.5‰ decrease in ␦ 18 O carb and ␦ 13 C carb deposited in lake sediments since ϳ1850 reflects higher rates of groundwater through-flow due to rainfall variability, land-use change, and increased rates of pumping over the past 40 yr. Calculated water residence times, based on the isotopic data, were 23 Ϯ 2 yr before 1850 and decreased by the late twentieth century to 8 Ϯ 2 yr. Concomitant dissolved inorganic carbon (DIC) residence times were 3.8 and 2.2 yr, respectively. Although burial rates of CaCO 3 have increased by about threefold over the past 40 yr, there is no evidence that substantial changes in organic carbon deposition has occurred. The shorter DIC residence time is largely due to increased input and higher CO 2 evasion rates. About 88% of C carb and ϳ96% of C org generated within the water column is remineralized, but the isotopic composition is essentially unaltered in the sediments. The measured variations in ␦ 13 C carb and ␦ 13 C org of sediments are thought to reflect changes to DIC residence time and increased CO 2 (aq) concentrations rather than changes in lake productivity.

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Section: Resultsmentioning

confidence: 99%

A modern isotope record of changes in water and carbon budgets in a groundwater‐fed lake: Blue Lake, South Australia

Herczeg

Leaney

Dighton

et al. 2003

Limnology & Oceanography

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“…Sample age was estimated using the constant rate of supply model described in ref. 52. Age-depth models for sediments older than 150 y were based on accelerator MS 14 C ages of terrestrial macrofossils.…”

Section: Methodsmentioning

confidence: 99%

Recent burning of boreal forests exceeds fire regime limits of the past 10,000 years

Kelly¹,

Chipman

Higuera

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

328

327

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Wildfire activity in boreal forests is anticipated to increase dramatically, with far-reaching ecological and socioeconomic consequences. Paleorecords are indispensible for elucidating boreal fire regime dynamics under changing climate, because fire return intervals and successional cycles in these ecosystems occur over decadal to centennial timescales. We present charcoal records from 14 lakes in the Yukon Flats of interior Alaska, one of the most flammable ecoregions of the boreal forest biome, to infer causes and consequences of fire regime change over the past 10,000 y. Strong correspondence between charcoal-inferred and observational fire records shows the fidelity of sedimentary charcoal records as archives of past fire regimes. Fire frequency and area burned increased ∼6,000–3,000 y ago, probably as a result of elevated landscape flammability associated with increased Picea mariana in the regional vegetation. During the Medieval Climate Anomaly (MCA; ∼1,000–500 cal B.P.), the period most similar to recent decades, warm and dry climatic conditions resulted in peak biomass burning, but severe fires favored less-flammable deciduous vegetation, such that fire frequency remained relatively stationary. These results suggest that boreal forests can sustain high-severity fire regimes for centuries under warm and dry conditions, with vegetation feedbacks modulating climate–fire linkages. The apparent limit to MCA burning has been surpassed by the regional fire regime of recent decades, which is characterized by exceptionally high fire frequency and biomass burning. This extreme combination suggests a transition to a unique regime of unprecedented fire activity. However, vegetation dynamics similar to feedbacks that occurred during the MCA may stabilize the fire regime, despite additional warming.

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“…Samples were counted for periods of 2-3 days, depending on the activity of 210 Po in the samples. 210 Pb dates were calculated using the constant rate of supply model (Binford 1990). Four plant fragments were dated by AMS 14 C at the laboratory of the Institute of Geological and Nuclear Sciences, New Zealand.…”

Section: Methodsmentioning

confidence: 99%

Increased precipitation during the Little Ice Age in northern Taiwan inferred from diatoms and geochemistry in a sediment core from a subalpine lake

et al. 2013

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We studied diatoms in a 55.5-cm-long sediment core from a subalpine lake in northern Taiwan, Tsuifong Lake (TFL), to investigate environmental changes from AD 490 to present. Diatom assemblages of the last century were dominated by acidophilous species, whereas alkaliphilous taxa dominated the record between AD 1480 and 1910. Over the studied time frame, four decadal periods with high precipitation were inferred from evidence of elevated soil input from the watershed, supported by the stable isotope signatures (d 15 N, d 13 C) of organic matter and magnetic susceptibility of the sediments. We compared the inferred changes in pH of TFL to values obtained from three other Taiwanese subalpine lakes. The present study revealed that elevated precipitation was associated with increased solar irradiance over the last five centuries, with a stable dry period between AD 490 and 1450. Acidification of TFL in the last *100 years was a consequence of deforestation and acid rain.

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Calculation and uncertainty analysis of 210Pb dates for PIRLA project lake sediment cores

Cited by 558 publications

References 14 publications

A modern isotope record of changes in water and carbon budgets in a groundwater‐fed lake: Blue Lake, South Australia

A modern isotope record of changes in water and carbon budgets in a groundwater‐fed lake: Blue Lake, South Australia

Recent burning of boreal forests exceeds fire regime limits of the past 10,000 years

Increased precipitation during the Little Ice Age in northern Taiwan inferred from diatoms and geochemistry in a sediment core from a subalpine lake

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