Abstract
Atmospheric dust plays an important role in terrestrial and marine ecosystems, particularly those that are nutrient limited. Despite that most dust originates from arid and semi-arid regions, recent research has shown that past dust events may have been involved in boosting productivity in nutrient-poor peatlands. We investigated dust deposition in a mid-latitude, raised bog, which is surrounded by a complex geology (paragneiss/schist, granite, quartzite and granodiorite). As proxies for dust fluxes, we used accumulation rates of trace (Ti, Zr, Rb, Sr and Y) as well as major (K and Ca) lithogenic elements. The oldest, largest dust deposition event occurred between ~8.6 and ~7.4 ka BP, peaking at ~8.1 ka BP (most probably the 8.2 ka BP event). The event had a large impact on the evolution of the mire, which subsequently transitioned from a fen into a raised bog in ~1500 years. From ~6.7 to ~4.0 ka BP, fluxes were very low, coeval with mid-Holocene forest stability and maximum extent. In the late Holocene, after ~4.0 ka BP, dust events became more prevalent with relatively major deposition at ~3.2–2.5, ~1.4 ka BP and ~0.35–0.05 ka BP, and minor peaks at ~4.0–3.7, ~1.7, ~1.10–0.95 ka BP and ~0.74–0.58 ka BP. Strontium fluxes display a similar pattern between ~11 and ~6.7 ka BP but then became decoupled from the other elements from the mid Holocene onwards. This seems to be a specific signal of the granodiorite batholith, which has an Sr anomaly. The reconstructed variations in dust fluxes bear a strong climatic imprint, probably related to storminess controlled by North Atlantic Oscillation conditions. Complex interactions also arise because of increased pressure from human activities.
Original language | English |
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Pages (from-to) | 507-518 |
Number of pages | 11 |
Journal | The Holocene |
Volume | 30 |
Issue number | 4 |
Early online date | 18 Sept 2019 |
DOIs | |
Publication status | Published - 4 Apr 2020 |
Bibliographical note
AcknowledgementsThe authors would like to extend their thanks to the students of the EcoPast research group (GI-1553, Universidade de Santiago de Compostela, Facultade de Bioloxía) and colleagues who helped with fieldwork and laboratory analyses.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship and/or publication of this article: This research was partially funded by Consiliencia network (ED431D2017/08 Xunta de Galicia) and Funding for Consolidation and Structuration of Research Units (ED431B2018/20 Xunta de Galicia).
Keywords
- peat records
- dust
- Holocene
- storminess
- NAO
- human activities
- PEAT BOG
- GREAT BOG
- STORE MOSSE
- IBERIAN PENINSULA
- NORTH-ATLANTIC OSCILLATION
- TRACE-ELEMENTS
- PB
- TIERRA-DEL-FUEGO
- SOIL-EROSION
- CLIMATE
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Timothy Mighall
- School of Geosciences, Geography & Environment - Personal Chair
- The North
Person: Academic