High spatial resolution analysis of sediment cores by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS)

A procedure is presented for the high-resolution analysis of lake sediment cores. Sections of a sediment core collected by freeze coring in a dimictic lake were prepared by slow drying. Clear visual laminations in the prepared sections indicated that the layering of accumulated sediments was preserved during sampling and sample preparation. Concentration profiles for Al, Si, Fe, S, As, Cu, and Zn at a 0.25-mm resolution were obtained for 2 core sections corresponding to pre-industrial and industrial periods. Detection limits of 0.09% for Al, 0.006% for Fe, 0.07% for S, 0.75% for Si, 0.7 µg g–1 for As, 68 µg g–1 for Cu, and 32 µg g–1 for Zn enable the analysis of these elements in the sediment samples. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis enabled the resolution of subannual patterns in element concentrations. In the lake studied, a regular, alternating pattern of Al and S concentrations appears to provide markers of annual sediment accumulation in the relatively uncontaminated layers of the core. In the more highly contaminated layers, LA-ICP-MS provides a suitable tool for the detailed study of pollution events