Search

The article discusses the use of tritium (H-3) and cesium (Cs-137) as temporal markers in ice cores extracted from temperate glaciers. We present a complete tritium profile for a 46 m ice core drilled from the Adamello Glacier, a temperate glacier in the Italian Alps, and compare it to the Cs-137 profile from the same ice core. Our analysis reveals tritium contamination between 19 and 32 m of depth, which can be attributed to the global radioactive fallout caused by atmospheric nuclear-bomb testing that took place in the 1950s and 1960s. Results show that the radioactive peak associated with 1963 does not occur at the same depth for both H-3 and Cs-137; instead, the tritium peak is 1.5 m above the cesium one. Our hypothesis is that this misalignment is caused by meltwater-induced post-depositional processes that affect Cs-137, which is more sensitive to percolation than H-3. The total inventory of Cs-137 in this ice core is also among the lowest ever reported, providing additional evidence that the presence of meltwater has affected the distribution of this radionuclide within the ice. In contrast, the total tritium inventory is comparable to what is reported in the literature, making it a more reliable temporal marker for temperate glaciers.

Paleoclimate and paleoenvironmental stratigraphic reconstructions from temperate glaciers are hindered by surface melting and ice metamorphism, which cause mobilization and concentration of impurities, as well as their interaction through englacial reactions. Despite meltwater intrusions, other impurities such as pollen grains and other palynomorphs remain to their original depth of deposition thanks to their large grain size. Temperate glaciers close to vegetated areas, therefore, can include palynomorphs of different types that i) can be reliable annual markers for ice-core dating and, ii) allow reconstructing paleoenvironmental changes through time. The Adamello Glacier (Central Alps, Italy) is a temperate glacier that extends over ca 14.35 km2 (2020) at elevations ranging between 2560 and 3420 m a.s.l. In the framework of the CLIMADA Project, a 224 m long ice core (ADA 270) was recovered in 2021 from Pian di Neve, the summit plateau at about 3200 m a.s.l. in the accumulation area of the glacier. Preliminary estimates date the surface ice of the glacier to the 1980s while the bottom of the core might be Medieval in age. Radionuclide-based dating (3H, 14C, 137Cs, 210Pb) is in progress. The multiproxy approach adopted in this study includes black carbon, dust grain size and mineralogy, oxygen and hydrogen stable isotopes and palynomorphs, these last being the main object of this work. Given the site location, the palaeoecological signal is believed to be of regional significance. Despite the stratigraphy may not be preserved for some soluble chemical species, the core contains a high variety of palynomorphs, which allow the reconstruction of palaeoenvironmental and paleoclimatic variations at subannual resolution. The mean ice accumulation rate is about 0.9 m w.eq. yr-1. Consequently, the mean sampling resolution adopted for the palynomorph study is 0.1 m, increased to 0.01 m in specific intervals. Palynomorphs are mainly found in layers representing the spring-sum

Ice-covered surfaces of the planet are a pristine glimpse on the climate history of the Earth. Their capability to reflect the solar radiation affects the energy budget through time, so that paleoclimatic information recorded in polar and mountain glaciers tell a story about climate and environmental changes. Climate variations are a glaring reality due to a progressive climate warming that has been observed since the 1950s. The latest 2022 IPCC report [1], highlights the worrying state of the entire cryosphere health. Mid-latitude glaciers, e.g., are highly sensitive to the current atmospheric warming, which is seriously compromising the quality of the signal preserved in the ice. Mineral dust aerosol in atmosphere can alter the Earth’s energy budget interacting with the solar electromagnetic radiation. The dust settled on glaciers surfaces varies the ice capability to reflect the incident radiation, so that a major portion of it is absorbed as a function of Light Absorbing Impurity (LAI) concentration, mineralogical composition, LAI shapes etc. Depending on formation sites different minerals have different optical properties, affecting cryosphere mechanisms in a way that has to be further investigated. Ice core studies from mid-latitude mountain glaciers are essential to infer recent climate variability and anthropogenic impact on a regional scale. In the scientific literature, various imaging non-destructive systems extract e.g. information from visual stratigraphy of ice cores [2]. Advanced techniques can further be developed to improve the accuracy of ice cores measurements, pursuing the preservation of such precious achieves. The aim of this work is to apply different approaches to improve the understanding and climate simulation models regarding ice optical properties and feedback mechanisms, focusing on mineral dust and ice internal features. First, a non destructive system based on a hyperspectral imaging sensor is used to analyze optical properties of ice

idea di chora e di di logos estetico in Platone