Holocene temporal and spatial variation in the radiocarbon reservoir age of three Danish fjords

Olsen, Jesper; Rasmussen, Peter; Heinemeier, Jan

doi:10.1111/j.1502-3885.2009.00088.x

Cited by 43 publications

(52 citation statements)

References 66 publications

(115 reference statements)

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“…In contrast, low reservoir ages ( R <0) can be caused by increased CO 2 exchange at the water-atmosphere boundary, or by surface-water runoff or mineralisation of contemporaneous terrestrial organic matter. Similar variations were found in other Danish fjords [29], with reservoir ages up to 900 years [28]. Other coastal environments show high reservoir ages as well: In a Swedish isostatically isolated basin, reservoir effects as high as R = 1,100 to 700 14 C years were measured on clay gyttja that was deposited during the most saline coastal Litorina phase [96].…”

Section: Sediment Core Samples From the Limfjordsupporting

confidence: 55%

“…A similar conclusion was reached by studies of three other Danish fjords [29] and the North Icelandic shelf [94]. In other studies, though, an influence of the habitat and diet of shellfish on the reservoir age has been observed (e.g.…”

Section: Sediment Core Samples From the Limfjordsupporting

confidence: 53%

“…Furthermore, the FRE influences radiocarbon dating in fjords and estuaries and can lead to site and time specific reservoir ages [28][29][30].…”

Section: Introductionmentioning

confidence: 99%

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The freshwater reservoir effect in radiocarbon dating

2013

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The freshwater reservoir effect can result in anomalously old radiocarbon ages of samples from lakes and rivers. This includes the bones of people whose subsistence was based on freshwater fish, and pottery in which fish was cooked. Water rich in dissolved ancient calcium carbonates, commonly known as hard water, is the most common reason for the freshwater reservoir effect. It is therefore also called hardwater effect. Although it has been known for more than 60 years, it is still less well-recognized by archaeologists than the marine reservoir effect. The aim of this study is to examine the order of magnitude and degree of variability of the freshwater reservoir effect over short and long timescales. Radiocarbon dating of recent water samples, aquatic plants, and animals, shows that age differences of up to 2000 14 C years can occur within one river. The freshwater reservoir effect has also implications for radiocarbon dating of Mesolithic pottery from inland sites of the Ertebølle culture in Northern Germany. The surprisingly old ages of the earliest pottery most probably are caused by a freshwater reservoir effect. In a sediment core from the Limfjord, northern Denmark, the impact of the freshwater reservoir effect on radiocarbon dating in an estuarine environment is examined. Here, freshwater influence causes reservoir ages to vary between 250 and 700 14 C years during the period 5400 BC -AD 700. The examples in this study show clearly that the freshwater reservoir effect can seriously corrupt radiocarbon dating at inland sites. Reservoir effects should therefore be considered whenever food remains on pottery or the bones of omnivores are radiocarbon dated -irrespective of the site's distance to the coast.

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Section: Sediment Core Samples From the Limfjordsupporting

confidence: 55%

Section: Sediment Core Samples From the Limfjordsupporting

confidence: 53%

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The freshwater reservoir effect in radiocarbon dating

2013

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“…Because of the known variability in the MRE, current research themes in the Northern Hemisphere (e.g. Reimer et al 2002;Ascough et al 2004Ascough et al , 2005aAscough et al ,b, 2006Ascough et al , 2007aAscough et al ,b, 2009Cage et al 2006;Mangerud et al 2006;Butler et al 2009;Olsen et al 2009;Martins 2009, 2010;Russell et al 2010) have focused on refining MRE values for specific locations and periods in time. The most common approach to quantifying these variations is the determination of R values, where a R value represents a regional offset from the global average surface water MRE (for which R = 0) (Stuiver et al 1986;Stuiver and Braziunas 1993).…”

Section: Introductionmentioning

confidence: 99%

Examining the Inherent Variability in ΔR: New Methods of Presenting ΔR Values and Implications for MRE Studies

et al. 2011

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ABSTRACT. Currently, there is significant ongoing research into the temporal and spatial variability of marine radiocarbon reservoir effects (MREs) through quantification of R values. In turn, MRE studies often use large changes in R values as proxies for changes in ocean circulation. R values are published in a variety of formats with variations in how the errors on these values are calculated, making it difficult to identify trends or to compare values, unless the method of calculating the R is explicitly described or all of the data are made available in the publication. This paper demonstrates the large range in R values (+34 to -122) that can be obtained from a single, secure archaeological context when using the multiple paired sample approach, despite the fact that the terrestrial entities were of statistically indistinguishable 14 C ages, as were the marine samples. This demonstrates the inherent variability in the R calculations themselves and we propose that, together with calculation of mean R, the distribution of R values should be displayed, e.g. as histograms in order to illustrate the full data range. This spread is only apparent when employing a multiple paired sample approach as the uncertainty derived on a single pair of samples, taking account only of the errors on the individual 14 C ages, will never truly represent the overall variability in R that results from the intrinsic variability in the population of 14 C ages in samples that might have been used. Consequently, R values and the associated uncertainty calculated from single pairs should be treated with some caution. We propose that, where possible, when using paired archaeological samples, that a multiple paired approach should be employed as it will test the context security of the material used in the R calculations. When summarizing the values by the weighted average, we also propose that the standard error for predicted values should be employed as this will fully encompass the uncertainty of a future R calculation, using different samples for a similar time and location. Finally, we encourage future publishing of R values using the histogram format, making all of the data available. This will help ensure that R values are comparable across the literature and should provide a framework for standardization of publication methods.

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“…It has a large central basin and is separated from the Kattegat by a threshold which does, however, still allow an inflow of saline Kattegat water towards the innermost parts of the fjord (Rasmussen 1973). The core chronology has previously been presented by Olsen et al (2009).…”

Section: Materials and Sediment Core Settingmentioning

confidence: 99%

The Baltic Sea inflow regime at the termination of the Medieval Climate Anomaly linked to North Atlantic circulation

Kuijpers

Kunzendorf

Rasmussen

et al. 2012

Baltica

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Baltic Sea water exchange is primarily governed by atmospheric forcing of the inflow of saline waters by strong westerly winds prevailing over the central North Atlantic and north-western Europe. Our sediment core study uses geochemical element records indicative of phytoplankton and cyanobacterial blooming as well as continent-derived mineral input for reconstructing hydrographic changes in the deeper Baltic Sea basins around AD 1200. An alkenone-based Sea Surface Temperature (SST) reconstruction for the relevant time span, AD 500-1500, is presented for another sediment core obtained from the shallow Isefjord located at the southern coast of the Kattegat at the entrance of the Baltic. At the termination of the Medieval Climate Anomaly at approximately AD 1200, the basin sediment facies and the geochemical records reveal an environmental change indicative of a marked decrease of inflow activity and marine productivity. This change coincides with a SST decrease and recently reported general fall in Kattegat sea level. A comparison with palaeo-climate data from the wider North Atlantic region demonstrates that this regime shift in Baltic Sea water exchange is linked to a large-scale change in ocean and atmosphere circulation from a dominating, positive North Atlantic Oscillation (NAO+) mode to more negative NAO conditions.

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Holocene temporal and spatial variation in the radiocarbon reservoir age of three Danish fjords

Cited by 43 publications

References 66 publications

The freshwater reservoir effect in radiocarbon dating

The freshwater reservoir effect in radiocarbon dating

Examining the Inherent Variability in ΔR: New Methods of Presenting ΔR Values and Implications for MRE Studies

The Baltic Sea inflow regime at the termination of the Medieval Climate Anomaly linked to North Atlantic circulation

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