Publication Date:
2024-02-14
Description:
Atmospheric dust samples collected along a transect off the West African coast have been investigated for their lipid content and compound-specific stable carbon isotope compositions. The saturated hydrocarbon fractions of the organic solvent extracts consist mainly of long-chain n-alkanes derived from epicuticular wax coatings of terrestrial plants. Backward trajectories for each sampling day and location were calculated using a global atmospheric circulation model. The main atmospheric transport took place in the low-level trade-wind layer, except in the southern region, where long-range transport in the mid-troposphere occurred. Changes in the chain length distributions of the n-alkane homologous series are probably related to aridity, rather than temperature or vegetation type. The carbon preference of the leaf-wax n-alkanes shows significant variation, attributed to a variable contribution of fossil fuel- or marine-derived lipids. The effect of this nonwax contribution on the d13C values of the two dominant n-alkanes in the aerosols, n-C29 and n-C31 alkane, is, however, insignificant. Their d13C values were translated into a percentage of C4 vs. C3 plant type contribution, using a two-component mixing equation with isotopic end-member values from the literature. The data indicate that only regions with a predominant C4 type vegetation, i.e. the Sahara, the Sahel, and Gabon, supply C4 plant-derived lipids to dust organic matter. The stable carbon isotopic compositions of leaf-wax lipids in aerosols mainly reflect the modern vegetation type along their transport pathway. Wind abrasion of wax particles from leaf surfaces, enhanced by a sandblasting effect, is most probably the dominant process of terrigenous lipid contribution to aerosols.
Keywords:
AEOLD; Aeolian dust sample; ALTITUDE; Calculated, see reference(s); Carbon number of the homologue with highest abundance; Carbon Preference Index, n-Alkanes (C25-C33); D1; D10; D11; D12; D13; D14; D15; D16; D17; D18; D19; D20; D21; D22; D23; D24; D25; D3; D4; D5; D6; D7; D8; D9; Event label; Gas chromatography - Mass spectrometry (GC-MS); GeoB; Geosciences, University of Bremen; Latitude of event; Longitude of event; M41/1; M41/1_D1; M41/1_D10; M41/1_D11; M41/1_D12; M41/1_D13; M41/1_D14; M41/1_D15; M41/1_D16; M41/1_D17; M41/1_D18; M41/1_D19; M41/1_D20; M41/1_D21; M41/1_D22; M41/1_D23; M41/1_D24; M41/1_D25; M41/1_D3; M41/1_D4; M41/1_D5; M41/1_D6; M41/1_D7; M41/1_D8; M41/1_D9; Meteor (1986); n-Alkane, average chain length; n-Alkane, C31/(C29+C31) ratio; n-Alkane, detected carbon number range; n-Alkane C24, δ13C; n-Alkane C25, δ13C; n-Alkane C26, δ13C; n-Alkane C27, δ13C; n-Alkane C28, δ13C; n-Alkane C29, δ13C; n-Alkane C30, δ13C; n-Alkane C31, δ13C; n-Alkane C32, δ13C; n-Alkane C33, δ13C; n-Alkane C4 plant; n-Alkane weighted mean, δ13C
Type:
Dataset
Format:
text/tab-separated-values, 350 data points
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