Tracking kelp-type seaweed fuel in the archaeological record through Raman spectroscopy of charred particles: examples from the Atacama Desert coast

The use of seaweed as fuel has been mentioned in ethnographic and historical sources of different coastal regions. Nevertheless, the archaeological record of seaweed burning is still limited to contexts where preservation is exceptional and macroscopic discrimination of charred remains is possible. Here, we evaluate the effectiveness of Raman spectroscopy in discriminating seaweed vs. plant/wood char. Our dataset (N = 92) consists of modern and archaeological seaweed and plant/wood charred remains, including specimens of unknown origin from the Atacama Desert coast, Northern Chile. The charred samples were processed to obtain 13 parameters which were then fed into five supervised machine learning models. The models, built on samples of known origin (seaweed and plant/wood), performed remarkably well in terms of accuracy, kappa, sensitivity, and specificity. The models were used for final predictions on 10 non-identified archaeological charcoals. Our results suggest that Raman spectroscopy combined with machine learning techniques is a robust methodology for discriminating seaweed and plant/wood charred remains in the archaeological record. The predictions on unknown samples confirm that seaweed was used as fuel in a specific funerary ritual in the southern Atacama Desert coast around 5000 cal BP. Furthermore, charred specimens of Lessonia spp. recovered from combustion features in other northern Chile coastal settlements, suggest that seaweed pyrotechnology developed by Atacama Desert coast people is likely a long-term process. As for coastal archaeology, this work encourages new research on seaweed as an alternative/main fuel in coastal deserts and evaluates possible bias for chronologies from coastal archaeological settlements around the globe.The present study was supported by the Universidad de Tarapacá (Chile) through the research grants UTA MAYOR 3754 (2021–2022) – “Uso de algas como combustible en sitios arqueológicos de la costa desértica de Atacama: una aproximación arqueomética” and UTA MAYOR 367122 (2022–2024) – “Estudio multiproxy para el reconocimiento de algas en rasgos de combustión arqueológicos de la costa del Desierto de Atacama” (Universidad de Tarapacá, Chile). D.Z. received financial support from the Arqueología, desiertos costeros y visibilización de recursos naturales Project (PIE 190405, CSIC) and ARVCODA – Arqueología de los Recursos Vegetales en la Costa del Desierto de Atacama project (Fundación PALARQ, CSIC). The studied samples were obtained during archaeological excavations or samplings performed in the following projects: FONDECYT 1151203; FONDECYT POSTDOC 3150664; and Quebrada Blanca Phase 2 (QB2) project – Compañía Minera Teck Quebrada Blanca S.A

Snow and ice in the desert: reflections from a decade of connecting cryospheric science with communities in the semiarid Chilean Andes

Citizen science and related engagement programmes have proliferated in recent years throughout the sciences but have been reasonably limited in the cryospheric sciences. In the semiarid Andes we at the Centro de Estudios Avanzados en Zonas Áridas have developed a range of initiatives together with the wider community and stakeholder institutions to improve our understanding of the role snow and ice play in headwater catchments. In this paper we reflect on ongoing engagement with communities living and working in and near study sites of cryospheric science in northern Chile as a strategy that can both strengthen the research being done and empower local communities

Envejecimiento de la población

•Actividades básicas de la vida diaria en personas mayores y factores asociados •Asociación entre depresión y posesión de mascotas en personas mayores •Calidad de vida en adultos mayores de Santiago aplicando el instrumento WHOQOL-BREF •Calidad de vida en usuarios con enfermedad de Parkinson, demencia y sus cuidadores, comuna de Vitacura •Caracterización de egresos hospitalarios de adultos mayores en Puerto Natales (2007-2009) •Comportamiento de las patologías incluidas como GES para el adulto mayor atendido en un Cesfam •Contribución de vitaminas y minerales a las ingestas recomendadas diarias en ancianos institucionalizados de Madrid •Estado de salud oral del paciente inscrito en el Programa de Visita Domiciliaria •Evaluación del programa de discapacidad severa en Casablanca con la matriz de marco lógico •Factores asociados a satisfacción vital en una cohorte de adultos mayores de Santiago, Chile •Pauta instrumental para la identificación de riesgos para el adulto mayor autovalente, en su vivienda •Perfil farmacológico del paciente geriátrico institucionalizado y posibles consecuencias en el deterioro cognitivo •Programa de cuidados paliativos y alivio del dolor en Puerto Natales •Rehabilitación mandibular implantoprotésica: efecto en calidad de vida relacionada con salud bucal en adultos mayores •Salud bucodental en adultos mayores autovalentes de la Región de Valparaíso •Transición epidemiológica y el estudio de carga de enfermedad en Brasi

Snow properties (including grain size, density, depth and isotopic composition), measured in the frame of the citizen science programme "Vecinos de las Nieves" in the semiarid Andes in Chile from 2018 to 2021.

Precipitation that falls as snow at high elevations is one of the principal water sources for the downstream areas in the dry Andes of Central Chile. The last decade was especially dry, with most years showing below-normal annual precipitation - the so-called central Chile megadrought. Together with increased water consumption, the dry conditions have led to considerable water stress. People living in high mountain areas are especially vulnerable to this water scarcity, which raises their awareness and interest in meteorological observations. This dataset contains measurements of fresh snow and rain obtained in the citizen science project Vecinos de las Nieves (Spanish for “snow neighbors”) - a collaboration between scientists and community members who live, work or study in the mountainous sector (above 1100 m asl.) in the Andes mountains of the Coquimbo region, Chile (29°S to 32°S). Since 2018, following each snowfall during the austral Winter (May to August), the volunteers have measured the physical-chemical characteristics of the snow on the ground. Since 2021, the volunteers have also collected rainfall with a manual rain gauge. In total, 21 precipitation events have been documented, with a maximum snow depth of 292 mm at the highest observation site (3110 m asl.). In addition, 25 fresh snow samples from 9 snowfall events have been collected and successfully processed, to derivate stable hydrogen and oxygen isotopes, whose values are in line with the global meteoric line. The program Vecinos de las Nieves has generated new scientific understanding of snow and rain processes during the four winter periods, as well as connected isolated communities in the pursuit of science, and has highlighted the importance of local knowledge and interdisciplinary research in understanding snow dynamics and water availability in this area. Most participants have observed drier conditions in their environment during the last years, with fewer snow events compared to previous years, showing growing concern about the water availability in the future

Envejecimiento de la población

•Actividades básicas de la vida diaria en personas mayores y factores asociados •Asociación entre depresión y posesión de mascotas en personas mayores •Calidad de vida en adultos mayores de Santiago aplicando el instrumento WHOQOL-BREF •Calidad de vida en usuarios con enfermedad de Parkinson, demencia y sus cuidadores, comuna de Vitacura •Caracterización de egresos hospitalarios de adultos mayores en Puerto Natales (2007-2009) •Comportamiento de las patologías incluidas como GES para el adulto mayor atendido en un Cesfam •Contribución de vitaminas y minerales a las ingestas recomendadas diarias en ancianos institucionalizados de Madrid •Estado de salud oral del paciente inscrito en el Programa de Visita Domiciliaria •Evaluación del programa de discapacidad severa en Casablanca con la matriz de marco lógico •Factores asociados a satisfacción vital en una cohorte de adultos mayores de Santiago, Chile •Pauta instrumental para la identificación de riesgos para el adulto mayor autovalente, en su vivienda •Perfil farmacológico del paciente geriátrico institucionalizado y posibles consecuencias en el deterioro cognitivo •Programa de cuidados paliativos y alivio del dolor en Puerto Natales •Rehabilitación mandibular implantoprotésica: efecto en calidad de vida relacionada con salud bucal en adultos mayores •Salud bucodental en adultos mayores autovalentes de la Región de Valparaíso •Transición epidemiológica y el estudio de carga de enfermedad en Brasi