Sulphate record from a northeast Greenland ice core over the last 1200 years based on continuous flow analysis

A 150 m deep ice core from the low-accumulation area of northeast Greenland was analyzed for sulphate, calcium, sodium and electrolytical meltwater conductivity at a depth resolution of approximately 1 cm by continuous flow analysis (CFA). The calcium and sodium profiles are used to establish a relatively precise ice-core chronology by annual-layer counting back to AD 830. Inspection of the novel CFA method for sulphate revealed relative errors typically around 15%, but at least +/-20 ng g(-1), for concentradons < 130 ng g(-1), and a current detection limit for routine ice-core analyses of 40 ng g(-1). Annual sulphate peaks are shown to occur over almost the entire core, with only a small shift in seasonality between the modern and pre-industrial sections. Inspection of volcanic horizons allowed more accurate timing of these peaks and clear identification of calcium-rich events. Disregarding clear volcanic peaks, significant long-term changes of sulphate are only seen over the industrial period. However, a higher frequency of important volcanic inputs was identified around AD 1200.