A paleolimnological reconstruction of mid and late holocene climate change in South Georgia

South Georgia is located at the barrier between Antarctica and the mid-latitudes which makes it a key location to determine the main drivers of past and present-day climate variability and to assess whether the climate in the South Atlantic was synchronous with Antarctica or South America. Here we performed a sedimentological, high resolution (ITRAX) geochemical, and fossil diatom and pigment analysis of a 5.41 m long, ca. 8000 cal yr BP, sediment core from Fan Lake, Annenkov Island, South Georgia (54°29’0’’S, 37°5’0’’W) in an attempt to separate the influence of Holocene palaeoclimatic variability from changes in catchment stability and glacier activity. While radiocarbon ages of events in the top 250 cm (c. 4 ka) of this core appear to be broadly in line with some other studies on South Georgia, the chronology of the lower half still poses several questions. The main lithological division in the profile is marked by the establishment of finely laminated sedimentation at c. 250 cm (4000 yrs BP) and is also picked out by the diatom and pigment analysis. This change is characterized by a reduction to low stable magnetic susceptibility values and a step-change increase in organic matter, and is most likely related to deglaciation of the lake catchment during the ‘Mid Holocene Hypsithermal’. Although the diatom composition is dominated by a single species (i.e., Cyclotella stelligera), relatively minor, but sometimes significant, fluctuations in other diatom species occur in the top 250 cm (mid-late Holocene). Interestingly, the most remarkable change in the diatom record occurs at c. 100 cm (1000 cal yr BP) and coincides with an increase in general lake productivity. We link these changes to increased catchment disturbance at c. 1000 cal yr BP, which is possibly associated with deglaciation following one of four relatively minor ‘post-cooling events’ during the late Holocene

Late Glacial and Holocene Palaeolake History of the Última Esperanza Region of Southern Patagonia

We undertook multi-proxy analyses on two sediment cores from Lago Pato, a small lake basin at 51°S topographically separated from Lago del Toro in Torres del Paine (TdP), to provide insights into glacier dynamics and lake-level change in the TdP and Última Esperanza region over the last ∼30,000 cal a BP (30 ka). Lago Pato is situated in a region overridden by the Southern Patagonian Ice Field during the Last Glacial and in a transitional climatic zone of Southern Patagonia sensitive to seasonal- to millennial-scale changes in the Southern Hemisphere Westerly Winds (SWW). Results show that a deep ice-dammed and enlarged palaeolake encompassed Lago del Toro and Lago Pato c. 30–20 ka after the ice had retreated from local-Last Glacial Maximum (l-LGM) limits at c. 48–34 ka and during the build-up to the global-Last Glacial Maximum (g-LGM), c. 26–19 ka. Gaps in both sediment records between c. 20–13.4 ka and c. 20–10 ka suggest hiatuses in sediment accumulation during the g-LGM and Antarctic Cold Reversal (ACR) readvances and/or removal by lake lowering or flushing during the Late Glacial–early Holocene. The palaeolake level dropped from >100 m a.s.l. to ∼40–50 m a.s.l. towards the end of the ACR c. 13.4–13.0 ka, creating a shallower glaciolacustrine environment dammed by an ice tongue in the Estancia Puerto Consuelo–Última Esperanza fjord. Further lowering of the enlarged palaeolake level occurred when the ice thinned to <40 m a.s.l., eventually isolating Lago Pato from Lago del Toro and glaciogenic sediment input at c. 11.7 ka. After isolation, the ecology and water levels in Lago Pato became sensitive to regional climate shifts. The shallow, stable, and highly anoxic environment that developed after c. 11.7 ka is associated with weaker (or poleward shifted) SWW at 51°S and was replaced at c. 10 ka by an increasingly productive shallow-littoral lake with a variable lake-level and periodic shifts in anoxic-oxic bottom water conditions and ratios of benthic-planktonic diatoms. A more open Nothofagus forest, established at c. 8.6–7.5 ka, and more arid conditions c. 7.5–5.7 cal ka BP are linked to another phase of weaker (or poleward shifted) SWW at 51°S. More persistently wet conditions from c. 5.7 ka, with extensive closed Nothofagus forests and planktonic diatoms dominant, are associated with stronger (or equatorward shifted) SWW over 51°S. The abrupt return of benthic-to-tychoplanktonic diatoms after c. 3 ka reflects enhanced SWW at 51°S. Increasingly stable lacustrine and littoral wetland conditions established in the last ∼500 years reflect weaker SWW and lasted until recent decades

Diatom distributions in space and time – a case study from the polar regions

第3回極域科学シンポジウム/第34回極域生物シンポジウム 11月27日（火） 統計数理研究所 ３階セミナー

Bulk organic geochemistry of sediments from Puyehue Lake and its watershed (Chile, 40°S) : implications for paleoenvironmental reconstructions

Author Posting. © Elsevier B.V., 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Palaeogeography, Palaeoclimatology, Palaeoecology 294 (2010): 56-71, doi:10.1016/j.palaeo.2009.03.012.Since the last deglaciation, the mid-latitudes of the southern Hemisphere have undergone considerable environmental changes. In order to better understand the response of continental ecosystems to paleoclimate changes in southern South America, we investigated the sedimentary record of Puyehue Lake, located in the western piedmont of the Andes in south-central Chile (40°S). We analyzed the elemental (C, N) and stable isotopic (δ13C, δ15N) composition of the sedimentary organic matter preserved in the lake and its watershed to estimate the relative changes in the sources of sedimentary organic carbon through space and time. The geochemical signature of the aquatic and terrestrial end-members was determined on samples of lake particulate organic matter (N/C: 0.130) and Holocene paleosols (N/C: 0.069), respectively. A simple mixing equation based on the N/C ratio of these end-members was then used to estimate the fraction of terrestrial carbon (ƒT) preserved in the lake sediments. Our approach was validated using surface sediment samples, which show a strong relation between ƒT and distance to the main rivers and to the shore. We further applied this equation to an 11.22 m long sediment core to reconstruct paleoenvironmental changes in Puyehue Lake and its watershed during the last 17.9 kyr. Our data provide evidence for a first warming pulse at 17.3 cal kyr BP, which triggered a rapid increase in lake diatom productivity, lagging the start of a similar increase in sea surface temperature (SST) off Chile by 1500 years. This delay is best explained by the presence of a large glacier in the lake watershed, which delayed the response time of the terrestrial proxies and limited the concomitant expansion of the vegetation in the lake watershed (low ƒT). A second warming pulse at 12.8 cal kyr BP is inferred from an increase in lake productivity and a major expansion of the vegetation in the lake watershed, demonstrating that the Puyehue glacier had considerably retreated from the watershed. This second warming pulse is synchronous with a 2°C increase in SST off the coast of Chile, and its timing corresponds to the beginning of the Younger Dryas Chronozone. These results contribute to the mounting evidence that the climate in the mid-latitudes of the southern Hemisphere was warming during the Younger Dryas Chronozone, in agreement with the bipolar see-saw hypothesis.This research was partly supported by the Belgian OSTC project EV/12/10B "A continuous Holocene record of ENSO variability in southern Chile". S.B. is supported by a BAEF fellowship (Belgian American Educational Foundation), and by an EU Marie Curie Outgoing Fellowship under the FP6 programme

ICTs, data and vulnerable people: a guide for citizens

ICTs, personal data, digital rights, the GDPR, data privacy, online security… these terms, and the concepts behind them, are increasingly common in our lives. Some of us may be familiar with them, but others are less aware of the growing role of ICTs and data in our lives - and the potential risks this creates. These risks are even more pronounced for vulnerable groups in society. People can be vulnerable in different, often overlapping, ways, which place them at a disadvantage to the majority of citizens; Table 3 in this guide presents some of the many forms and causes of vulnerability. As a result, vulnerable people need greater support to navigate the digital world, and to ensure that they are able to exercise their rights. This guide explains where such support can be found, and also answers the following questions: - What are the main ethical and legal issues around ICTs for vulnerable citizens? - Who is vulnerable in Europe? - How do issues around ICTs affect vulnerable people in particular? This guide is a resource for members of vulnerable groups, people who work with vulnerable groups, and citizens more broadly. It is also useful for data controllers1 who collect data about vulnerable citizens. While focused on citizens in Europe, it may be of interest to people in other parts of the world. It forms part of the Citizens’ Information Pack produced by the PANELFIT project, and is available in English, French, German, Italian and Spanish. You are welcome to translate this guide into other languages. Please send us a link to online versions in other languages, so that we can add them to the project website

Merging science education, citizen science and general population noise exposure data collection in the battle against noise pollution

Science, Technology, Engineering, Mathematics in education is commonly referred to as STEM. The last decades illustrate that our society is transferring into an ever accelerating technological environment. In parallel, the general public became an important driving force in collecting citizen science data to trigger legislative pressure and impact on policy makers to accelerate the improvement of their quality of life. That practice is currently extending into the environmental impact of noise related quality of life. This publication suggests to merge those educational STEM goals, citizen science monitoring and the need for population based noise monitoring data for efficient policy support. The presented educational project can be regarded as a proof-of-concept and can be repeated in different schools and classes every year. This approach has the potential to acquire abundant noise monitoring data and provides an unbiased population sampling dataset by design. This population driven involvement allows to assess real-life and long-term noise policy impact and could become a fundamental pillar in achieving the overall societal goal of improving noise related environmental quality of life

Congruence and disparity in benthic diatom community structure of small lakes in New Zealand and Tasmania

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Hydrological and land-use changes in the Cuzco region (Cordillera Oriental, South East Peru) during the last 1200 years: a diatom-based reconstruction

A quantitative diatom analysis was carried out on a sediment core from the small infilled lake basin of Marcacocha (Cuzco-region, SE Peru), in order to reconstruct environmental changes between 800 and 1850 AD. Five stratigraphical zones were distinguished by means of constrained cluster analysis. Very few diatoms were present between 790 and 1070 AD, probably reflecting dry and cool conditions, at a time when anthropogenic impact was limited around the basin. The transition at ca. 1070 AD was the most pronounced, and corresponded with a marked shift towards higher temperatures, as deduced from plant macroremains and the pollen record. This coincided with a sudden climate shift from cold and dry conditions towards warmer and even drier conditions, as recorded elsewhere in tropical South America. Between 1070 and 1650 AD diatoms (mainly the genus Epithemia Ktzing) became more abundant, together with charophyte oospores, suggesting the existence of a stable, shallow lake. The transition in diatom composition and abundances at ca. 1650 AD, with peaks centered on 1700 AD, lag behind the start of the Little Ice Age (around 1490-1530 AD), though match increased cooling at the end of the 17th and early 18th century as recorded in Peruvian ice cores. This could be caused by a threshold that was passed after the lake level had lowered sufficiently due to a cooling and drying climate, as well as infilling processes. Further transitions in the diatom community may be interpreted less in terms of climatic change, but as increasing sensitivity to local environmental changes, such as a lake level decrease and lake infilling. A hiatus in diatom abundance observed between ca. 1750 and 1810 AD, could be associated with increasing colonization of Juncaceae around the lake margin and rapid infilling, possibly linked to the construction of drainage canals clearly visible today. The final stage of infilling occurred after ca. 1845 AD, with complete colonization of the remaining lake surface by Juncaceae, with further accumulation of peats