We use a PDZ Europa 2020 Mass Spectrometer (MS-2020; now supplied by Sercon Ltd., UK) with a coupled self-constructed laser fluorination line for analyzing stable oxygen isotopes in biogenic silica samples (diatoms, radiolaria, sponge spicules). Our research focuses mainly on Arctic lake systems. For measuring stable oxygen isotopes in biogenic silica, a sediment sample undergoes several preparation steps including wet chemistry and heavy liquid separation to achieve a pure opal sample (> 97% …