Results from a 85 ka old sediment sequence from Lake Petén Itzá, Gutemala, show extreme cooling of the Neotropics of up to 10 C during Heinrich Events (Hodell et al., 2012) and suggest high climate sensitivity for the older sediment sections of about 200 ka. It is proposed to analyze the consequences of abrupt climate change on the stability of aquatic ecosystems over time and consequently the historical biogeography of the Peninsula Yucatán by using ostracodes as model bioindicators interlinking three major research topics. A (1) quantitative assessment of lake level changes during the past 200 ka is targeted by expanding an existing trainingset of recent ostracodes and refining transfer functions for water depth and conductivity. (2) Fossil ostracode assemblages will be used to reconstruct the ultrastructure of Late Pleistocene climate extremes and their effects on aquatic diversity of Lake Petén Itzá, and (3) to assess biogeography, phylogeography and phylogeny of freshwater ostracodes as model organisms by integrative taxonomy using morphology and molecular tools. In order to initiate research efforts on Lake Petén Itzá sediments extending beyond 85 ka a core sampling party for the Petén Itzá Scientific Drilling Project at LacCore, University of Minnesota, is proposed. This will also further strengthen the collaboration with Central America and prepare for future ICDP-drilling in Lake Junin (Peru) and planned work on Lake Chalco (Mexico Basin).
Leading Questions: - Climate change in southern Arabia over the last several 100000 years: - Change of location and intensity of the Indian Ocean monsoon; - Relationship between continental and marine climate records; -Relationships between climate and human activity. Abstract: Our paleoclimate work in Oman is based on two types of deposits, carbonate cements in alluvial gravels and cave deposits. The results of our initial study of gravel cements suggested that rainfall in Oman was at one time considerably greater than at present, possibly due to more vigorous monsoonal circulation and rainfall in the past, and that oxygen and carbon isotope ratios are related to the amount of rainfall an area receives. We are presently further investigating this hypothesis by analyzing cave deposits, which should be a more easily datable and more continuous record of paleoclimate. We have sampled cave systems in both northern and southern Oman. The research we plan for these samples focuses on using the oxygen and carbon stable isotope record together with U/Th dating to interpret how climatic conditions have varied over perhaps the last few 100 ka or longer. Petrography of these samples, particularly UV-fluorescence, will aid in sample selection and in interpreting the climatic record.
Responding to the twin crises of global warming and biodiversity loss requires a deep understanding of how climate affects the processes that generate and destroy biodiversity, primarily through its effects on the ecology and distribution of species. Recent improvements in our ability to reconstruct the history of biodiversity through timed phylogenies, estimate changes in genetic diversity, and predict the potential distribution of selected species with ecological niche models (ENMs) now allow us to infer the evolution of ecological preferences and distributional ranges at different temporal scales. Our two case studies focus on alpine/arctic regions, because they are among those most endangered by global warming. The first study will use, for the first time, a combination of ENM and phylogeny to test the model of hybrid, polyploid speciation by secondary contact in arctic/alpine plants. We selected Primula sect. Aleuritia (simply Aleuritia, from here on), because our previous phylogenetic work provided clear hypotheses for the parental origins of polyploids, yet the distributions of the inferred progenitors do not currently overlap. Did the ranges of the proposed parents overlap at the time of allopolyploid origins, as predicted by the secondary contact model? To answer this question, we will produce a high-resolution, dated phylogeny of Aleuritia, optimize the ecological preferences of the hypothesized progenitors onto the dated phylogeny, and project their past distributional ranges onto the fine-resolution climatic scenarios recently developed for the Pleistocene. In the second case study, we will try to explain how small populations persisted on summits in the past and how they are affected by current and future climate change. Here we selected Saxifraga florulenta, a rare, endemic species of the Maritime Alps, because hypotheses of its phylogenetic relationships are available from our previous work, it occurs exclusively above 2000 m, and has very narrow ecological requirements. Consequently, if current trends of global warming continue, the strict ecological adaptation of S. florulenta to siliceous substrates at the highest altitudes of the Maritime Alps may represent a serious extinction risk. We will investigate whether the phylogeographic history, genetic diversity, climatic niche and dispersal mode of S. florulenta can explain its long persistence in the Maritime Alps, a hot spot of biodiversity, and predict its future survival or extinction on mountain tops. We will use a combination of genetic analysis and niche modeling to reconstruct changes in the niche, geographic distribution, and genetic diversity of this cold-adapted species.
Landscape and soil changes are strongly coupled to chemical and physical (erosion) weathering and soil production. The erosion rate is preserved in the signal of cosmogenic nuclides (e.g., 10Be) in stream sediments or even directly in a soil profile. The genesis of clastic sediments and soils has been investigated to quantify processes occurring within source areas and catchments, including chemical and physical weathering, and textural and compositional modification of detritus during transition from bedrock to grus and thereafter to soil or a fluvial environment. Well-defined (or -controlled) settings are however needed to calculate mass balances for a given (tectonically active) catchment. Measurements of mid- to long-term erosion rates have recently become more widely available through cosmogenic nuclide techniques. Still, new approaches can be developed to improve our understanding of weathering processes and their rates. Ideal settings and a considerable dataset about mineral weathering are given for the Sila massif in southern Italy (and consequently in a Mediterranean environment). It represents a tectonically active area. The upland plateaus consist of old planation surfaces, bordered by steep slopes, and are characterised by granitic spheroidal boulders which form wide boulder fields. The combination of the major tectonic and relief features with typical upland Mediterranean climate conditions promoted the triggering of severe erosion, that led to the exhumation of the boulders. Data about soil erosion amounts and rates related to the soil formation period would complete the puzzle of the driving forces and enable a more detailed interpretation of landscape and soil evolution. These boulders seemed to 'grow' out of the surface with time. Consequently, by measuring the 10Be content at different levels along a rock boulder (from the soil surface to the top of boulders), the age(s) of exposure could be derived and subsequent total denudation rates will be obtained. This would be an elegant way to calculate erosion rates for different time-steps that cover almost the entire period of soil evolution. Such an approach would give insight into a) the overall denudation and erosion rates over the whole (potential) soil formation period and b) erosion and denudation rates during time segments and would allow for the distinction of different erosion phases during the Pleistocene and Holocene c) volumes of loose material that were removed from the uplands and entered the drainage river system in this time span. (...)
The investigation of sediment cores from two of the largest freshwater lakes from Western Europe (lakes Geneva and Lucerne) demonstrated that natural sources of trace elements dominated before the European industrial revolution. The heavy metal pollution (e.g. lead, mercury) highly increased following the industrialization of Switzerland after 1850. The implementation of wastewater treatment plants (WWTPs) in the 1960s significantly decreased the metal pollution at the deepwater sites. By contrast, the Vidy Bay of Lake Geneva where are released the WWTP of the city of Lausanne since 1964 was highly contaminated by heavy metals due to the WWTP emissions. Lead isotopic composition furthermore highlighted the industrial pollution sources over the last 200 years. During the twentieth century, industrial releases multiplied by 10 times heavy metal fluxes to hydrological systems located on both sides of the Alps. The remote and small high altitude lake Meidsee (2661 m a.s.l. in the Southwestern Alps) revealed the strong increase in anthropogenic trace metal deposition during the Greek and Roman Empires (ca 300 BC to AD 400), the Late Middle Ages (ca AD 1400), and the Early Modern Europe (after ca AD 1600). The greatest increases in anthropogenic metal pollution were evidenced after the industrial revolution of ca AD 1850, especially in Lake Lucerne where industrial activities and the steamboat navigation released high amounts of fossil fuel combustion residues and heavy metals. The elemental and isotopic composition of sedimentary organic matter from the high-altitude Lake Meidsee provided additional information about the high-altitude Alpine landscape evolution since the Late Pleistocene/Holocene deglaciation in the Swiss Southwestern Alps; and indicated the predominant deposition of algal-derived organic matter with limited input of terrestrial organic matter before the Holocene Climatic Optimum (between 7.0 and 5.5 years ago). This research also investigated faecal indicator bacteria (Escherichia coli and Enterococcus), multiple antibiotic resistant and antibiotic resistance genes, in sediment profiles from different parts of Lake Geneva (Switzerland) over the last decades. Results showed that the WWTP input constituted the main source of pollution for several contaminants, including heavy metals, antibiotics, and antibiotic-resistant bacteria. The Bay of Vidy of Lake Geneva can therefore be considered as a reservoir of bacteria multiple resistance genes. Hence, the human-induced eutrophication in the 1970s highly enhanced the sediment microbial activity, and therein the spreading of antibiotic resistant bacteria and genes in this aquatic environment used to supply drinking water in a highly populated area.
The phenomenon of shifting desert margins during Pleistocene and Holocene times shall be analysed on Namibian territory. The Eastern boarder of the Namib Desert as well as the Western part of the Kalahari, react on climatic fluctuations or changes (key-words: Paleomonsoon, Mega-ENSO events) by altering their ecosystems and geomorphodynamics. Following the todays ephemeral rivers from the Namibian highlands or Great Escarpment trough the Namib, fluvial deposits and eolian sediments are investigated with the aim to identify magnitude, frequency, duration and absolute age of climatic variations in arid and semiarid environments.
Die Persistenz der Benguela-Zirkulation seit dem Miozaen (Mittleres Tertiaer) erlaubte im Hinterland der Wueste Namib nur Klimaschwankungen innerhalb semiarider Rahmenbedingungen. Dies fuehrte mit hoher Wahrscheinlichkeit im Wechsel von endorheischer Entwaesserung und Sedimentakkumulation der Trockenfluesse (Riviere) zu episodischen beziehungsweise phasenweisen Durchbruechen zum Meer. Die hygrischen Veraenderungen sind daher - besonders im Jungpleistozaen und Holozaen - in Flussterrassen beziehungsweise Flutauslaufsedimenten der Wueste resp. in ihrem Ostrandbereich gut dokumentiert. Ziel ist es, von punktuellen Untersuchungen der Ablagerungen wegzukommen und die Akkumulationen weitraeumig zueinander in Beziehung zu setzen sowie mit modernem Methodenrepertoire ueber diese geomorphodynamischen Zeugnisse der Identifizierung und zeitliche Eingrenzung / Datierung hygrischer Veraenderungen ('Paleomonsoon' und 'Mega-El Ninos') innerhalb des namibischen Territoriums waehrend des Pleistozaens und Holozaens zu erreichen. Auf diese Weise sollen bislang fehlende Eckdaten zur Rekonstruktion der raeumlichen Veraenderungen der Namib-Ostgrenze im Grenzsaum zwischen noerdlicher Randstufenluecke und suedlichem Kaokoveld erarbeitet werden. Eine Korrelation der Ergebnisse mit den Erkenntnissen aus der Untersuchung anderer 'Desert Margins' (im Rahmen des International Geological Correlation Programm, IGCP 349) wird angestrebt. Mit Hilfe von stratigraphischen Untersuchungen und absoluten Altersbestimmungen am flusialen und aeolischen Schluffablagerungen (Silte) wird eine genauere zeitliche Aufloesung holozaener Feuchte-/Ariditaetsschwankungen im gesamten namibischen Bereich versucht.
Das Vorhaben will die Archive im Flussgebiet des noerdlichen Oberrheins untersuchen. Die Flussentwicklung hat im Laufe des ausgehenden Pleistozaens und im Holozaen dynamische Wandlungen durchgemacht, die Auswirkungen auf die Oberflaechenform, die Sedimentation und die Bodenbildung hatten. Die Vielzahl der Maeandersysteme erlaubt eine gute Aufloesung der drei Zeitscheiben (ZS). In der ersten ZS vollzieht sich der Uebergang von furkativer zu maeandrierender Dynamik. Auf Umlaufflaechen entstehen Tschernoseme. Die zweite ZS zeichnet sich durch den Wechsel von Gross- zu Kleinmaeandern mit gravierendem Wechsel der Sedimente (humose Auenlehme) aus. In die dritte ZS faellt ein erneuter Wechsel zu staerker furkativem Verlauf mit grobkoernigeren schluffigen Sedimenten. Neben der lateralen Differenzierung der Maeandersysteme existiert auch eine vertikale Differenzierung der Auenlehmdecke. Zu deren Gliederung und Datierung wird neben flussmorphologischen Aspekten und stratifizierbaren Sedimenten insbesondere die Bodengenese untersucht.
The East Mediterranean Coastal Plain is composed mainly of alternating sands, soils and gravel of Pleistocene-Holocene age, indicating the alternation of marine, coastal and continental environments. Archaeological/geological surveys previously conducted on the coastal plain by the principal investigators, show that until modern times the sand layers had always been empty of human occupation. Archaeological remains are found only in the paleosols which have formed between successive episodes of sand accumulation. From a human geography point of view, then, in periods of sand accumulation the coastal plain turned into a virtual desert. An attempt will be made to interpret past desertification processes by assessing actual processes of sand transportation and accumulation on the Israeli Coast. For the first time reliable chronological framework will be obtained by means of systematic application of improved method of absolute dating. This project will bring both geological and archaeological evidence in close interaction so as to elucidate the impact of adverse natural events on human subsistence and survival from prehistoric times. Present-day pattern of sand migration and distribution of grain size, shape and mineralogy along the Mediterranean coast of Israel will be examined. Present-day sand pattern will be compared with past sand along 10 east-west geotraverses across the coastal plain. A more reliable chronological framework for sand accumulation and periods of soil formation will be developed by the application of systematic luminescence dating using a combination of OSL and TL techniques. The chronological information attained will then be used to correlate the terrestrial evidence with the ocean core record (deep sea and Mediterranean record).
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