TY  - JOUR
AU  - Wang, Ye
AU  - Moradi, Ghazal
AU  - Klumpp, Erwin
AU  - von Sperber, Christian
AU  - Tamburini, Federica
AU  - Ritter, Benedikt
AU  - Fuentes, Barbara
AU  - Amelung, Wulf
AU  - Bol, Roland
TI  - Phosphate oxygen isotope fingerprints of past biological activity in the Atacama Desert
JO  - Geochimica et cosmochimica acta
VL  - 311
SN  - 0016-7037
CY  - New York, NY [u.a.]
PB  - Elsevier
M1  - FZJ-2021-04882
SP  - 1 - 11
PY  - 2021
AB  - The Atacama Desert (Chile) is one of driest places on Earth, with a hyper-arid climate and less than 2 mm yr−1 precipitation; nevertheless, it has experienced rare periods of sporadic rainfall. These periods shortly enhanced vegetation growth and microbial activity, which must have utilized major nutrients such as phosphorus (P). However, any biological cycling of P involves an oxygen exchange with water, which should now reside in the hyperarid soils as tracer of life. In order to identify such evidences, we performed sequential P fractionation and analyzed the oxygen isotope composition of HCl-extractable phosphate (δ18OHCl–P) in the surface soil (0–15 cm) of a climatic gradient along the rising alluvial fans of the Central Depression to the Precordillera, Chile. At the driest sites, the δ18OHCl-P values were constant with depth and deviated from biologically-driven isotopic equilibrium. In contrast, we observed a considerable increase of δ18OHCl-P values below the soil surface at less arid sites, where some isotope values were even within the range of full isotopic equilibrium with biologically cycled phosphate. For the latter sites, this points to most efficient biological P cycling right below the uppermost surface of the desert. Critically, the absolute concentrations of this biologically cycled P exceeded those of P potentially stored in living microbial cells by at least two orders of magnitude. Therefore, our data provides evidence that δ18OHCl-P values trace not recent but past biological activity, making it a powerful tool for assessing the existence, pathways and evolution of life in such arid ecosystems on Earth and, thus, potentially on other planets such as Mars.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000693337600001
DO  - DOI:10.1016/j.gca.2021.07.027
UR  - https://juser.fz-juelich.de/record/903159
ER  -