The role of oceanic primary production on climate variability has long been debated. Defining changes in past oceanic primary production can help understanding of the important role that marine algae have in climate variability. The changes in primary production could have influenced CO2 sequestration into the ocean and hence affect the radiative forcing of the Earth's atmosphere. Methanesulfonic acid (MSA) is the chemical marker in the ice core archive commonly used for assessing changes in past primary production. MSA is produced by the marine biota but its concentration could be influenced by other environmental parameters such as changes in sea ice extension. Although MSA concentrations were preserved in cold storage conditions for up to 15 years, MSA is able to diffuse through solid ice cores. The determination of other compounds, able to give an indication of past marine productivity, is crucial. Other organic compounds, such as free amino acids, can be produced and emitted into the atmosphere during a phytoplankton bloom. For the first time, free L- and D-amino acids in Arctic snow and firn samples were determined by a sensitive and selective analytical method based on liquid chromatography coupled with tandem mass spectrometry. The new method for the determination of free amino acids concentrations was applied to firn core samples collected on April 2015 from the summit of the Holtedahlfonna glacier, Svalbard (N 79?08.424, E 13?23.639, 1120 m a.s.l.). Here we also investigate the correlation between the concentration of chlorophyll-a, marker of marine primary production, and amino acids present in an ice core to evaluate the possible application to paleoclimatic studies. The main results of this work are summarized as follows: (1) glycine, alanine and proline, were detected and quantified in the firn core samples; (2) their concentration profiles, compared with that of the stable isotope ?18O ratio, show a seasonal cycling with the highest concentrations during the spring and summer time; (3) back-trajectories and Greenland Sea chlorophyll-a concentrations obtained by satellite measurements were compared with the amino acids profile obtained from ice core samples, this provided further insights into the present results. This study suggests that the amino acid concentrations in the ice samples collected from the Holtedahlfonna glaciers could reflect changes in oceanic phytoplankton abundance.
Free amino acids in the Arctic snow and ice core samples: Potential markers for paleoclimatic studies
E Barbaro;A Spolaor;R Zangrando;C Barbante;
2019
Abstract
The role of oceanic primary production on climate variability has long been debated. Defining changes in past oceanic primary production can help understanding of the important role that marine algae have in climate variability. The changes in primary production could have influenced CO2 sequestration into the ocean and hence affect the radiative forcing of the Earth's atmosphere. Methanesulfonic acid (MSA) is the chemical marker in the ice core archive commonly used for assessing changes in past primary production. MSA is produced by the marine biota but its concentration could be influenced by other environmental parameters such as changes in sea ice extension. Although MSA concentrations were preserved in cold storage conditions for up to 15 years, MSA is able to diffuse through solid ice cores. The determination of other compounds, able to give an indication of past marine productivity, is crucial. Other organic compounds, such as free amino acids, can be produced and emitted into the atmosphere during a phytoplankton bloom. For the first time, free L- and D-amino acids in Arctic snow and firn samples were determined by a sensitive and selective analytical method based on liquid chromatography coupled with tandem mass spectrometry. The new method for the determination of free amino acids concentrations was applied to firn core samples collected on April 2015 from the summit of the Holtedahlfonna glacier, Svalbard (N 79?08.424, E 13?23.639, 1120 m a.s.l.). Here we also investigate the correlation between the concentration of chlorophyll-a, marker of marine primary production, and amino acids present in an ice core to evaluate the possible application to paleoclimatic studies. The main results of this work are summarized as follows: (1) glycine, alanine and proline, were detected and quantified in the firn core samples; (2) their concentration profiles, compared with that of the stable isotope ?18O ratio, show a seasonal cycling with the highest concentrations during the spring and summer time; (3) back-trajectories and Greenland Sea chlorophyll-a concentrations obtained by satellite measurements were compared with the amino acids profile obtained from ice core samples, this provided further insights into the present results. This study suggests that the amino acid concentrations in the ice samples collected from the Holtedahlfonna glaciers could reflect changes in oceanic phytoplankton abundance.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.