An open-ocean assessment of alkenone δD as a paleo-salinity proxy

Gould, Jessica; Kienast, Markus; Dowd, Michael; Schefuß, Enno

doi:10.1016/j.gca.2018.12.004

Cited by 14 publications

(19 citation statements)

References 57 publications

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“…The δ 2 H C37 ratios were corrected for global ice volume using the ANICE model (de de Boer et al, ) and the global meteoric water line (Craig & Gordon, ; equation ). From these ice volume‐corrected δ 2 H C37 ratios, salinity shifts were calculated using three different equations: the surface sediment calibration of Weiss et al (; equation ), the E. huxleyi batch culture calibration (Schouten et al, ; equation ), and the SPOM calibration from Gould et al (; equation ). Equation yielded a substantial salinity range from 23 to 42 psu, with a value of 24 for the most modern sample (Figure ).…”

Section: Resultsmentioning

confidence: 99%

“…Using equation gave a value of 32 for the most recent sample, which is in better agreement with modern measured values from the site than equation , although still underestimating the modern value of 33.8. Applying the Atlantic and Pacific SPOM calibration from Gould et al () (equation ) provided an equivalent range of 6 psu (Figure ). The most modern sample had a salinity of 34, which aligns nicely with the modern day salinity of 33.8 (Mix et al, ).…”

Section: Resultsmentioning

confidence: 99%

“…Reconstructed salinities (psu) for ODP 1234 using the marine surface sediment calibration from Weiss et al () in green with a slope of 1.3, the linear regression equation from Schouten et al () batch culture experiment growing Emiliania huxleyi in light purple with a slope of 4.8, and the SPOM calibration from Gould et al () in dark blue with a slope of 4.2. The surface sediment calibration yielded a salinity shift of ~19 psu over the entire record, whereas the E. huxleyi and SPOM equations covered a more reasonable salinity shift of ~5 psu across the record.…”

Section: Resultsmentioning

confidence: 99%

“…Salinity was calculated from ice volume‐corrected δ 2 H C37 ratios using a surface sediment calibration (Weiss et al, ):

δ^{2} H_{normalC 37} = 1.3 \times normalS - 227

and, to contrast with the smaller sensitivity, the culture calibration from Schouten et al () for E. huxleyi :

δ^{2} H_{normalC 37} = 4.8 \times normalS - 347

and the SPOM calibration from Gould et al ():

δ^{2} H_{normalC 37} = 4.2 \times normalS - 340

…”

Section: Methodsmentioning

confidence: 99%

“…However, the slopes of the linear regression equations for the relationship between δ 2 H C37 ratios and salinity vary considerably between culture experiments, ranging from 4.8 (Schouten et al, ) to 1.3 (Sachs et al, ), equating to a 4.8‰ or 1.3‰ change in δ 2 H C37 ratio per practical salinity unit (psu), respectively. Alkenones in marine surface sediments had a 1.3‰ response to salinity (Weiss et al, ), and alkenones in suspended particulate organic matter (SPOM) from the Atlantic and Pacific Oceans had a δ 2 H C37 –salinity response of 4.2 (Gould et al, ). These large differences make it difficult to quantitatively constrain past salinity changes.…”

Section: Introductionmentioning

confidence: 99%

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Paleosensitivity of Hydrogen Isotope Ratios of Long‐Chain Alkenones to Salinity Changes at the Chile Margin

Weiss

Bar

Stolwijk

et al. 2019

Paleoceanog and Paleoclimatol

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Hydrogen isotope ratios of long-chain alkenones (δ 2 H C37 ratios) have been shown to correlate with salinity in several culture studies. However, it is uncertain how applicable the δ 2 H C37 -salinity relationship is to reconstruct past salinity. The δ 2 H C37 ratios were measured on sediments from a drill core (ODP site 1234) at the Chilean Margin covering the last~150 kyr. High δ 2 H C37 values corresponded to glacial time periods and interglacial periods are characterized by lower δ 2 H C37 values, aligning with δ 18 O ratios measured on planktonic foraminifera from the same core. Effects of parameters such as species composition, the δ 2 H-δ 18 O relationship used for ice volume corrections, and nutrient-or light-controlled growth rate, did not appear to significantly alter δ 2 H C37 ratios at ODP 1234. We used linear regression equations from batch culture experiments, marine surface sediments, and suspended particulate organic matter to quantitatively characterize salinity changes over the last~150 kyr at ODP 1234. However, most of these equations yielded larger salinity shifts than previously suggested, a phenomenon also observed for other δ 2 H C37 records. This suggests that the paleosensitivity of δ 2 H C37 ratios to salinity was larger in the geologic record than has been observed in any modern environment or laboratory settings, or that glacial to interglacial salinity shifts might have been larger than currently believed.

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