Mineral dust as a driver of carbon accumulation in northern latitudes

Malin E Kylander,A Martínez-Cortizas,Johan Rydberg,Jenny K Sjöström,Richard Bindler,Joeri Kaal,Kerry Gallagher,Noemí Silva-Sánchez,Sarah L Greenwood,Sophia V Hansson,Sebastien Rauch,Carl-Magnus Mörth

doi:10.1038/s41598-018-25162-9

Abstract

Peatlands in northern latitudes sequester one third of the world’s soil organic carbon. Mineral dusts can affect the primary productivity of terrestrial systems through nutrient transport but this process has not yet been documented in these peat-rich regions. Here we analysed organic and inorganic fractions of an 8900-year-old sequence from Store Mosse (the “Great Bog”) in southern Sweden. Between 5420 and 4550 cal yr BP, we observe a seven-fold increase in net peat-accumulation rates corresponding to a maximum carbon-burial rate of 150 g C m−2 yr−1 – more than six times the global average. This high peat accumulation event occurs in parallel with a distinct change in the character of the dust deposited on the bog, which moves from being dominated by clay minerals to less weathered, phosphate and feldspar minerals. We hypothesize that this shift boosted nutrient input to the bog and stimulated ecosystem productivity. This study shows that diffuse sources and dust dynamics in northern temperate latitudes, often overlooked by the dust community in favour of arid and semi-arid regions, can be important drivers of peatland carbon accumulation and by extension, global climate, warranting further consideration in predictions of future climate variability.

Highlights

In previously glaciated regions of the mid- and high-latitudes climatic conditions are often wet and cold, providing optimal environments for peat accumulation, where primary productivity exceeds ecosystem respiration
As peatlands develop over time their upper layers can be increasingly isolated from the local hydrology and the surface vegetation eventually becomes reliant on atmospheric deposition alone for nutrient supply
The nutrient balance of terrestrial ecosystems can be positively affected by dust deposition[4] even at large spatial scales like that seen in the cross-continental fertilization of the Amazon rainforest by P and Fe-rich dust from the Bodélé depression[12]

Summary

Results and Discussion

Store Mosse is typical of Sphagnum-dominated bogs in terms of the observed botanical transitions, bulk densities, OM content, C and N contents and C/N ratios[22] (Fig. 2). Humification and dust deposition data from Store Mosse suggest that the climate during the HPAE was relatively wet[18] This is corroborated by regional lake-level records[34,35] and the generally wet and cold conditions described in western Europe at this time[36], possibly linked to the abrupt termination of Bond Event 437 (Fig. 2e). The importance of the dust quality over the quantity is evidenced by the lower correlation between PAR and Al MAR (r = 0.21, P > 0.05) and the greater scatter between these parameters in biplot space (Fig. 5a–d) This boosted productivity is enhanced by the higher water table of the time, which would decrease peat decomposition, further increasing PAR. Even in the temperate northern latitudes, often overlooked by the dust community, dust dynamics can be an important driver of ecosystem productivity, and thereby, carbon storage and global climate

Methods

Author Contributions

Additional Information