פרמפרוסט וההתחממות הגלובלית דרך משקפיה של מארי קירי

ישי ויינשטיין, אוניברסיטת בר אילן

More than 20% of the land surface area is covered by permafrost. Global warming has already caused extensive permafrost degradation, and some models predict up to 60% reduction in permafrost areal extent by the end of the 21st century. This may result in the oxidation of its very large organic carbon inventory and the consequent release of greenhouse gases to the atmosphere, amplifying global warming. Conventional methods of studying permafrost degradation rely on ground thermal measurements, active layer monitoring and modeling. While some geochemical characterization of ground ice does exist, direct methods of tracking permafrost thawing and of tracing its thawed water in local drainage systems were hardly developed. In a study of Holocene permafrost in Adventdalen, Svalbard, we­­­­­­ identified a distinct radium isotope signature of permafrost ground ice. This includes the ratios of 226Ra to the short-lived isotopes 224Ra and 223Ra, which are higher in the permafrost than in the active soil, and the 224Ra/228Ra ratio, which is lower in the first. Both signals are attributed to the cryogenic nature of the permafrost pore space. The permafrost radium fingerprints were also identified in a local stream water, which suggests that although not observed by the indirect methods, the Adventdalen permafrost has recently been defrosting. We suggest that being a generic fingerprint, radium isotopes could be used as permafrost signature also in other permafrost terrains.  We will also show that radium isotopes are useful tools to determine the time scales involved in the formation of ice bodies within the permafrost and to study permafrost-associated artesian water.


תאריך 17/06/2018 10:30 12:00
הדפסשלח לחבר
עבור לתוכן העמוד