title: Automated Measurement of Magnesium/Calcium Ratios in Gastropod Shells Using Laser-Induced Breakdown Spectroscopy for Paleoclimatic Applications.
abstract: The chemical composition of mollusk shells offers information about environmental conditions present during the lifespan of the organism. Shells found in geological deposits and in many archeological sites can help to reconstruct past climatic conditions. For example, a correlation has been found between seawater temperature and the amount of some substituent elements (e.g., magnesium, strontium) in the biogenerated calcium carbonate matrix of the shell, although it is very species-specific. Here we propose the use laser-induced breakdown spectroscopy (LIBS) to estimate Mg/Ca ratios in modern specimens of the common limpet Patella vulgata. An automated setup was used to obtain a sequence of Mg/Ca ratios across a sampling path that could be compared with the seawater temperatures recorded during the organism's lifespan. Results using four shells collected in different months of the year showed a direct relationship between the Mg/Ca ratios and the seawater temperature, although the sequences also revealed small-scale (short-term) variability and an irregular growth rate. Nevertheless, it was possible to infer the season of capture and the minimum and maximum seawater temperatures from the LIBS sequences. This fact, along with the reduction in sampling and measurement time compared with other spectrometric techniques (such as inductively coupled plasma mass spectrometry [ICP-MS]), makes LIBS useful in paleoclimatic studies.
authors.affiliation: 1 Grupo de Ingeniería Fotónica, Departmento TEISA, Universidad de Cantabria, Spain.
authors.forename: Adolfo
authors.initials: A
authors.lastname: Cobo
authors.affiliation: 2 Instituto Internacional de Investigaciones Prehistóricas de Cantabria, Universidad de Cantabria, Spain.
authors.forename: Asier
authors.initials: A
authors.lastname: García-Escárzaga
authors.affiliation: 2 Instituto Internacional de Investigaciones Prehistóricas de Cantabria, Universidad de Cantabria, Spain.
authors.forename: Igor
authors.initials: I
authors.lastname: Gutiérrez-Zugasti
authors.affiliation: 3 Departamento de Ciencia e Ingeniería del Terreno y de los Materiales, Universidad de Cantabria, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Setién
authors.affiliation: 2 Instituto Internacional de Investigaciones Prehistóricas de Cantabria, Universidad de Cantabria, Spain.
authors.forename: Manuel R
authors.initials: MR
authors.lastname: González-Morales
authors.affiliation: 1 Grupo de Ingeniería Fotónica, Departmento TEISA, Universidad de Cantabria, Spain.
authors.forename: José Miguel
authors.initials: JM
authors.lastname: López-Higuera
mesh_terms: D060105:Animal Shells / Q000737:chemistry*; D000818:Animals; D002118:Calcium / Q000032:analysis*; D002980:Climate; D049851:Gastropoda / Q000737:chemistry*; D057230:Limit of Detection; D016014:Linear Models; D008274:Magnesium / Q000032:analysis*; D010163:Paleontology / Q000379:methods*; D015203:Reproducibility of Results; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D008274:Magnesium; D002118:Calcium
keywords: LIBS; Laser-induced breakdown spectroscopy; laser spectroscopy; paleoclimate