Assessment of δ¹³C and C/N ratios in bulk organic matter as palaeosalinity indicators in Holocene and Lateglacial isolation basin sediments, northwest Scotland

Abstract

2007. Assessment of 13 C and C/N ratios in bulk organic matter as palaeosalinity indicators in Holocene and Lateglacial isolation basin sediments, northwest Scotland.ABSTRACT: Carbon isotopes (d 13 C) and C/N ratios from bulk organic matter have recently been used as alternative proxies for relative sea-level (RSL) reconstruction where there are problems associated with conventional biological indictors. A previous study on a single isolation basin (Upper Loch nan Eala) in northwest Scotland has shown a clear relationship between d 13 C, C/N ratios and palaeosalinity from Younger Dryas and Holocene aged sediments. In this paper we present results of d 13 C and C/N ratio analyses from other isolation basins in northwest Scotland over the Holocene and the Lateglacial period in order to validate this technique. The results from the Holocene sequences support the earlier findings that this technique can be used to identify RSL change from isolation basins over the Holocene in this region. The relationship between d 13 C, C/N ratios and RSL change is not apparent in sediments of Lateglacial age. Other environmental variables such as atmospheric CO 2 concentration, poor vegetation development and temperature influence d 13 C values during this period.

The freshwater reservoir effect in radiocarbon dating

“…The potential of sediment δ 13 C values as salinity proxy was already suggested by Hedenström and Possnert, 2001 [96], and further explored by e.g. Mackie et al [101,102]. The salinity changes observed in zones 3 to 4 are suggested to show increased marine influence in the western part of the Limfjord (through the western opening of the fjord towards the North Sea), whereas the northern http://www.heritagesciencejournal.com/content/1/1/24 openings diminished as a result of isostatic uplift, aeolian sand transport and redeposition of sediment by ocean currents, mainly the Jutland Current.…”

A paleolimnological archive of metal sequestration and release in the Cumberland Basin Marshes, Atlantic Canada

“…In Unit 2, C/N values were greater than 20, indicating predominantly sustained allochthonous, terrestrial organic input (Meyers and Teranes 2001). The C/N vs. δ 13 C biplot also supported this interpretation, with values plotting within the C3 plant range (Meyers and Lallier-Vergés 1999;Mackie et al 2007). …”

“…The C/N values (between 10 and 20) indicated that both terrestrial and aquatic carbon sources contributed to lake sedimentation (Meyers and Teranes 2001); however, the C/N vs. δ 13 C biplot (Fig. 4) indicated that the aquatic carbon likely had a strong freshwater affinity (Mackie et al 2007). The Cl concentrations were low and indicated that saltwater egress did not occur during this interval (Branchu and Bergonzini 2004).…”

The Palaeolimnology of Lough Murree, A Brackish Lake in the Burren, Ireland

“…Lagoon isolation has been inferred for Norwegian (Mills et al 2009;Balascio et al 2011) and Scottish (Mackie et al 2005;Mackie et al 2007) basins, which transformed into freshwater coastal lakes as a result of isostacy or land uplift. However, natural forcing is unlikely since Irish coasts, with the exception of a small portion of Northern Ireland, are submergent (Gehrels 2010).…”

“…C/N ratios of c. 9 have been attributed to benthic algal communities in shallow water sediments (Sundbäck et al 2000). Algae and macrophytes have a wide range of d 15 N (Finaly and Kendall 2007) and values of c. 2 at the base of LM2 core are possibly representative of phytoplankton (Maksymowska et al 2000;Rossi et al 2010). Basal core diatom records have relatively high concentrations (9.00 ) 10 5 frustules g (1 WW), are mainly composed of benthic species and assemblages comprising marine and brackish taxa, including high levels of Paralia sulcata.…”