The 800 year long ion record from the Lomonosovfonna (Svalbard) ice core

We present a high‐resolution record of water‐soluble ion chemistry from a 121 m ice core spanning about 800 years. The core is well dated to 2/3 depth using cycle counting and reference horizons and a simple but close fitting model for the lower 1/3 of the core. This core suffers from modest seasonal melt, and so we present concentration data in decadal running means to minimize percolation effects. Sea‐salt ions (Na + , Cl − , Mg 2+ , and K + ) account for more than 70% of all ions. In general, sea‐salt ion concentrations are rather variable and have no clear association with climatic variations. Sulfate, with 74% being from non‐sea‐salt sources, has higher concentrations than seen on Vestfonna ice cap but lower than in Ny‐Ålesund aerosols, suggesting central Spitsbergen receives more marine (westerly) air masses than Ny‐Ålesund but more sulfate enriched (easterly) air masses than Nordaustlandet. Clear anthropogenic impacts are found for sulfate, nitrate, and ammonium (and probably excess chloride) after the mid twentieth century, with sulfate showing a significant rise by the end of the nineteenth century. Sulfate and methanesulfonate concentrations correlate well during the twentieth century, and it is clear that most of the preindustrial sulfate is of biogenic origin. Terrestrial component (Ca 2+ ) has the highest concentrations in the coldest part of the Little Ice Age, suggesting more windy conditions, transporting local terrestrial dust to the ice cap. All ion concentrations decrease at the end of the twentieth century, which reflects loss of ions by runoff, with non‐sea‐salt magnesium being particularly sensitive to melting.