Holocene peatland palaeoclimate archives and aeolian dust deposition

The reconstruction of past water table levels in ombrotrophic peatlands is a long-established method for studying past regional hydroclimatic conditions. Peat strata are typically investigated for biological (e.g. plant macrofossils, testate amoebae, pollen) and geochemical (e.g. peat decomposition products and water isotopes) evidence to reconstruct bog surface wetness (BSW) at individual sites or to reconstruct the isotopic qualities of the precipitation that mire plant species used to synthesise plant tissues. Integration of BSW records across regions is then used to understand the temporal and spatial patterns of regional hydroclimatic variability. However, in recent years there has been increasing recognition that internal processes in the peatlands themselves and allogenic factors, such as mineral dust deposition and other forms of aerial pollution, could confound attempts to produce a clear picture of past hydroclimatic variability from peatlands. This study explores the impact of wind-blown mineral deposition on bog functioning in both high deposition environments (Japan and UK) and in a low deposition region (Northern Newfoundland) to understand how these inputs might impact possible climate signals preserved in raised peat strata. The examination of this ‘dust gradient’ shows that there may be multiple climate-driven signals in peat and that the contribution of long distance aeolian transport can be discerned when local inputs are minimal.