Universität zu Köln

Khormali, Farhad, Shahriari, Ali, Ghafarpour, Amin, Kehl, Martin ORCID: 0000-0003-4587-5858, Lehndorff, Eva and Frechen, Manfred (2020). Pedogenic carbonates archive modern and past precipitation change - A transect study from soils and loess-paleosol sequences from northern Iran. Quat. Int., 552. S. 79 - 91. OXFORD: PERGAMON-ELSEVIER SCIENCE LTD. ISSN 1873-4553

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Abstract

Stable carbon and oxygen isotope compositions in soil carbonates and in soil organic matter provide insights into (paleo) climatic conditions, especially in arid and semiarid regions where carbonate is abundant in soils. We here investigate delta C-13 and delta O-18 isotope composition of bulk carbonate, pedogenic carbonate nodules and organic carbon from modern soils developed along a precipitation gradient (Entisol, Inceptisol, Mollisol and Alfisol) and paleosols formed within loess units in northern Iran. delta C-13 values of organic carbon in the modern soils ranged from -19.5 parts per thousand in the arid and semiarid regions to -24 parts per thousand in the more humid regions with forest vegetation. delta C-13 values of bulk carbonate in the modern soils ranged from -12.1 parts per thousand at the wettest sites to -0.8 parts per thousand at the drier sites and thus, a 550 mm increase in precipitation leads to a similar to 11 parts per thousand decrease in delta C-13 values of bulk carbonate. In the modern soils, delta C-13 values of pedogenic carbonate nodules in the semiarid areas show higher values by similar to 3-4 parts per thousand more than the regions with forest vegetation. Unlike delta C-13 values of pedogenic carbonate nodules the delta O-18 values of pedogenic carbonate nodules of modern soils in this study did not display pronounced changes across the sections. The change in delta C-13 of carbonates and organic carbon is consistent with the present aboveground vegetation, consisting of a mosaic of habitats with differences in the proportion of C-3 and C-4 vegetation tending to larger C-4 contribution with increasing aridity. The delta C-13 values of carbonates coupled with climate data of the region confirm seasonal bias in the formation of carbonate nodules in the modern soils seen in studies elsewhere. The delta C-13 values of pedogenic carbonate nodules in the paleosols range from -10 parts per thousand in humid areas to -7.2 parts per thousand in semiarid areas. The trends in delta C-13 composition in modern soils are also visible in the delta C-13 composition in the paleosols, suggesting that in the foothills of the Alborz and Iranian loess plateau, a precipitation gradient existed also in the last interglacial.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Khormali, Farhad UNSPECIFIED UNSPECIFIED UNSPECIFIED Shahriari, Ali UNSPECIFIED UNSPECIFIED UNSPECIFIED Ghafarpour, Amin UNSPECIFIED UNSPECIFIED UNSPECIFIED Kehl, Martin UNSPECIFIED orcid.org/0000-0003-4587-5858 UNSPECIFIED Lehndorff, Eva UNSPECIFIED UNSPECIFIED UNSPECIFIED Frechen, Manfred UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-328758
DOI:	10.1016/j.quaint.2019.12.011
Journal or Publication Title:	Quat. Int.
Volume:	552
Page Range:	S. 79 - 91
Date:	2020
Publisher:	PERGAMON-ELSEVIER SCIENCE LTD
Place of Publication:	OXFORD
ISSN:	1873-4553
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language STABLE ISOTOPIC COMPOSITION; WASHINGTON-STATE; DELTA-C-13 VALUES; VEGETATION CHANGE; C-13-O-18 BONDS; ATMOSPHERIC CO2; PALOUSE REGION; ORGANIC-CARBON; LATE MIOCENE; C-4 GRASSES Multiple languages Geography, Physical; Geosciences, Multidisciplinary Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/32875