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Temporal changes in the amounts of trace elements (As, Co, Cu, Mn, Ni, Pb, and Zn) and their correlations with temporal changes in charcoal abundance in age-dated sediments collected from Lake Thompson in Patagonia, Chile, attest to the substantial pyrogenic remobilization of contaminants that occurred in Patagonia during the mid-1900s. This remobilization was concurrent with the extensive slash and burn period in the region during that period. The changes in concentrations of Co, Cu, and Ni in relation to charcoal abundance in the lacustrine sediments over time were small compared to those of As, Mn, Pb, and Zn. However, the relatively low enrichment factors of all those trace elements, normalized to Fe, indicate that they were predominantly derived from local, natural sources impacted by fires rather than industrial sources. The primarily local source of Pb in the sediments was corroborated by the temporal consistency of its isotopic ratios ( 206 Pb/ 207 Pb: 208 Pb/ 206 Pb), which were similar to previously reported values for natural lead in Central and Southern Chile. However, the pyrogenic remobilization of both natural and industrial trace elements by forest fires in Chile and elsewhere is expected to rise as a consequence of climate change, which is projected to increase both the frequency and intensity of forest fires on a global scale.

2Patagonia is commonly seen as an exceptionally pristine area because of its wildlife and practically unpolluted 3 waters. However, during the twentieth century the burning of natural forests was one of the most important 4 human activities in Northern Chilean Patagonia. Some estimations indicate that three million hectares were 5 burned during the first three decades of the century being its impacts rarely assessed. Hence the objective of this 6 study was to evaluate the impacts of the historical fires in Lake Burgos (45º42'S) and Lake Thompson (45º38'S) 7 in Chilean Patagonia. The impact was measured by evaluating chironomid assemblage since they are sensitive 8 enough to be used as an indicator of aquatic ecosystem health. Fires have a direct and drastic effect on a lake 9 watershed but also indirectly affect a lake ecosystem, changing sedimentation patterns or increasing nutrient 10 inputs. In the studied lakes the periods with higher prevalence of fires were identified by charcoal analysis, 11 while organic matter and magnetic susceptibility allowed to confirm the pre-fire and post-fire periods. The 12 chironomid composition was evaluated through a PCA and an analysis of similarity (ANOSIM) to test the 13 significance among periods while a DCA was applied to the chironomid assemblage downcore to assess 14 compositional structure and taxa turnover. In Lake Burgos the ANOSIM test indicated significant differences 15 between the pre-fire and fire periods (p<0.05), while in Lake Thompson differences were not significant.

Due to its tectonic setting, the Andean Southern Volcanism Zone (SSVZ) is characterized by frequent volcanic activity. Chilean Patagonia lake sediments represent powerful archives of historical and past eruptions since the deglaciation. The lacustrine tephra record is investigated in 10 Holocene sedimentary cores collected in five lakes located along a 45-47 degrees transect through Northern Chilean Patagonia. All the tephras identified by visual observation and strong magnetic susceptibility signal have been characterized for the major chemical composition of their glass shards by microprobe analyses, bulk mineralogical content by x-ray diffraction analyses and grain-size distribution by laser diffraction. Special care has been given to the chronostratigraphical framework in order to determine the age interval for each tephra layer and further to correlate the lacustrine records. The sedimentary age models are based on Pb-210 data and calibrated radiocarbon dates measured on macroremains or reservoir effect-corrected bulk sediment. To present a more complete tephrochronological record, 28 microtephras have been confirmed by their mineralogical signature. Our lacustrine tephra record is compared with the Holocene eruptions registered in both surface deposits and continental, lacustrine and peat bog, environments. The different lacustrine eruption records are discussed according to their origin, age and location (distance from volcanoes, wind direction and dispersion of eruption produced). Our data confirm that Chilean Ande SSVZ tephras are mainly derived from historical and past Hudson eruptions. However, the peculiar low-K2O signature of the glass shards observed in one tephra layer from the Northernmost lake, Lake Thompson, confirms an influence from some other SSVZ volcanoes with low-abundance magma type, such as Maca and Cay. Our tephrochronological data compliment the database for volcanic activity in Chile bringing new information essential for the running discussion on the temporal distribution of eruptions over the Holocene

Understanding past climate variability is important for obtaining better predictions of future changes. Documentary records are high temporal resolution proxies that can be used to reconstruct aspects of the climate, such as precipitation. Vicuña Mackenna developed a compilation of historical climatic events between the 16th and 19th centuries using chronicles from Spanish colonizers and town council records. The objective of this work was to classify dry and wet periods beginning in the 16th century using records from Vicuña Mackenna by generating a precipitation index based on events in the documentary evidence (e.g., epidemics, “pro pluvia” rogations, and infrastructural damage) into a simple annual precipitation index on an ordinal scale. The index used a three‐term classification scale, with 0 representing normal years, 1 representing wet years, and −1 representing dry years. The documentary records were not substantial enough to identify wet/dry periods during the 16th and 17th centuries. However, it was possible to identify dry and wet years described by conquerors and settlers that first arrived in the study area. During the 18th century, two long periods of drought were identified: 1705 to 1718 and 1770 to 1797. During these droughts, people organized rogations to the Virgen and different saints in desperation due to the lack of water. Finally, during the 19th century, technological improvements in measuring precipitation made it possible to identify intermittent dry and wet periods with higher resolution and precision, and these events could be related to the El Niño–Southern Oscillation (ENSO).