Advancing towards high-quality water isotope measurements in ice cores: a micro-destructive approach using Laser Ablation coupled with Cavity Ring Down Spectroscopy

Abstract

Addressing the intricate challenges of water isotope analysis in polar ice cores, especially in extracting detailed climate records from older and thinner ice layers, the innovative integration of Laser Ablation (LA) with Cavity Ring Down Spectroscopy (CRDS) is introduced. The micro-destructive LA technique, which employs a nanosecond excimer pulsed laser operating at 193 nm for ice surface irradiation, demonstrates potential in achieving continuous, high-resolution sampling and gas phase sample generation, complementing the CRDS analyzer's precision in measuring water isotopes in gaseous state. Recent advancements include the successful adaptation of an existing LA system, previously coupled with an Inductively Coupled Plasma - Mass Spectrometer (ICP-MS) for ice core impurity analysis, to establish a connection with the CRDS analyzer. This was accomplished by making adjustments to the coupling procedure and laser parameters, to ensure efficient gas sample generation and robust delivery for water isotope analysis. A method for creating ice standard samples by transforming liquid water standards into ice yielded ice isotope standards, crucial for setting up initial measurement protocols. Their implementation on both standard ice samples and sections of ice cores revealed valuable insights into areas for improvement. This represents a significant step towards establishing a reliable method for high-quality water isotope analysis in ice cores, aiming to significantly enrich our understanding of long-term climate trends.