The C32 alkane-1,15-diol as a tracer for riverine input in coastal seas
Lattaud, J.; Kim, J.-H; de Jonge, C.; Zell, C.; Sinninghe Damsté, J.S.; Schouten, S. (2017). The C32 alkane-1,15-diol as a tracer for riverine input in coastal seas. Geochim. Cosmochim. Acta 202: 146-158. https://dx.doi.org/10.1016/j.gca.2016.12.030
In: Geochimica et Cosmochimica Acta. Elsevier: Oxford,New York etc.. ISSN 0016-7037; e-ISSN 1872-9533, meer
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| Trefwoord |
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| Author keywords |
Long chain diols; Long chain Diol Index; 1,13-,1,14- and 1,15-diols; C32 1, 15-diol; River outflow; Terrigenous output; Sea Surface Temperature |
| Abstract |
Long chain alkyl diols are lipids that occur ubiquitously in marine sediments and are used as a proxy for sea surface temperature (SST), using the Long chain Diol Index (LDI), and for upwelling intensity/high nutrient conditions. The distribution of 1,13- and 1,15-diols has been documented in open marine and lacustrine sediments and suspended particulate matter, but rarely in coastal seas receiving a significant riverine, and thus continental organic matter, input. Here we studied the distribution of diols in four shelf seas with major river outflows: the Gulf of Lion, the Kara Sea, the Amazon shelf and the Berau delta, covering a wide range of climate conditions. The relative abundance of the C32 1,15-diol is consistently higher close to the river mouth and particularly in the suspended particulate matter of the rivers suggesting a terrigenous source. This is supported by statistical analysis which points out a significant positive correlation between the C32 1,15-diol and the Branched and Isoprenoid Tetraether index, a proxy reflecting soil and riverine input in marine environments. However, the C32 1,15-diol was not detected in soils and is unlikely to be derived from vegetation, suggesting that the C32 1,15-diol is mainly produced in rivers. This agrees with the observation that it is a dominant diol in most cultivated freshwater eustigmatophyte algae. We, therefore, suggest that the relative abundance of the C32 1,15-diol can potentially be used as a proxy for riverine organic matter input in shelf seas. Our results also show that long chain alkyl diols delivered by rivers can substantially affect LDI-reconstructed SSTs in coastal regions close to river mouths. |
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