Driving mechanisms of Holocene lagoon development and barrier accretion in Northern Elis, Peloponnese, inferred from the sedimentary record of the Kotychi Lagoon

As part of the lagoon barrier accretions plain characterizing the NW coast of the Peloponnese, the Kotychi Lagoon is believed to have formed in the prograding delta of the Palaeo-Peneus River over 7000 years ago. Geochemical/sedimentological proxies-data (XRF, grain size, OC-, IC-, C/N-analysis) combined with Bayesian age-depth-modeling revealed that from 8500 to 8000 cal BP marine conditions were prevailing. Around 8000 cal BP, a short-lived sequence of coastline progradation and barrier accretion created lagoonal conditions. Thus, the first chronological control for the onset of lagoon formation in coastal Elis is presented. Pronounced lagoonal conditions developed approximately 6300 cal BP, simultaneously to the period of circum-Mediterranean lagoon formation. A rapidly varying sedimentary record indicates a phase of geomorphological instability between 5200 and 3500 cal BP terminating with the erosional unconformity of a river channel. This evolution reflects a two-phase development: (1) Early Holocene morphology was controlled by the postglacial sea level rise; (2) with receding of the ice sheets by mid-Holocene, the preeminent role of the eustatic signal was overwhelmed giving local and regional processes, such as human-induced soil erosion and climatic forcing an accentuated role. Thus, the evolution of the Elean coastline shows analogies to circum-Mediterranean lagoon formation.researc

The Influence of Olive Orchards Copper-Based Fungicide Use, in Soils and Sediments—The Case of Aetoliko (Etoliko) Lagoon Western Greece

In this study, soil and aquatic sediments were sampled in the Aetoliko Lagoon and its catchment area, which is exclusively dominated by olive orchards. For the first time in Greece, soil as well as sediments samples of one coherent protected aquatic ecosystem were directly compared. In order to determine the influence that the usage of copper-based fungicides have on the lagoon sediments and on the soils of the surrounding area, twenty five (25) soil samples from different olive orchards that are bordering the water body and ten (10) sediment samples from the bottom of the lagoon were taken. The samples were analyzed for total copper content (total digestion) and extractable copper (diethylenetriaminepenta acetic acid, DTPA, extraction method). Furthermore, soil/sedimentological and geochemical analyses such as pH, grain size, total organic carbon, total sulfur, total nitrogen, and calcium carbonate content were carried out. The results show that the total copper in soils ranges from 58.37 to 671.33 mg kg −1 . In addition the DTPA-extractable copper in soils has an average value of 45.00 mg kg −1 . The average value of total copper in soils (286.24 mg kg −1 ) is higher than the threshold value for the Cu concentration (100 mg kg −1 ) set by the EU countries. Total copper content in the lagoon sediments is lower than in soils and varies between 43.85 mg kg −1 and 71.87 mg kg −1 . The DTPA-extractable copper in sediments is in low ranges from 0.14 to 0.60 mg kg −1 . On average, the total copper value for the lagoon sediments (55.93 mg kg −1 ) exceeds the Toxicity Screening Value (25.20 mg kg −1 ) for Cu in freshwater sediments. From the present study, it is clear that, although the copper in soils of the surrounding lagoon area exceeds the threshold limit for ecological risk, the lagoon sediments are influenced in a smaller degree. Our study can be used as a valuable reference and baseline for future studies on the environmental monitoring of the Aetoliko lagoon, as well as for studies in similar ecosystems

Preliminary hydrogeological interpretation of the Aigion area from the AIG10 borehole data

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Regional environmental change versus local signal preservation in Holocene thermokarst lake sediments: A case study from Herschel Island, Yukon (Canada)

Thermokarst lakes cover nearly one fourth of ice-rich permafrost lowlands in the Arctic. Sediments from an athalassic subsaline thermokarst lake on Herschel Island (69°36′N; 139°04′W, Canadian Arctic) were used to understand regional changes in climate and in sediment transport, hydrology, nutrient availability and permafrost disturbance. The sediment record spans the last ~ 11,700 years and the basal date is in good agreement with the Holocene onset of thermokarst initiation in the region. Electrical conductivity in pore water continuously decreases, thus indicating desalinization and continuous increase of lake size and water level. The inc/coh ratio of XRF scans provides a high-resolution organic-carbon proxy which correlates with TOC measurements. XRF-derived Mn/Fe ratios indicate aerobic versus anaerobic conditions which moderate the preservation potential of organic matter in lake sediments. The coexistence of marine, brackish and freshwater ostracods and foraminifera is explained by (1) oligohaline to mesohaline water chemistry of the past lake and (2) redeposition of Pleistocene specimens found within upthrusted marine sediments around the lake. Episodes of catchment disturbance are identified when calcareous fossils and allochthonous material were transported into the lake by thermokarst processes such as active-layer detachments, slumping and erosion of ice-rich shores. The pollen record does not show major variations and the pollen-based climate record does not match well with other summer air temperature reconstructions from this region. Local vegetation patterns in small catchments are strongly linked to morphology and sub-surface permafrost conditions rather than to climate. Multidisciplinary studies can identify the onset and life cycle of thermokarst lakes as they play a crucial role in Arctic freshwater ecosystems and in the global carbon cycle of the past, present and future

AMS-14C-Analysen zur Rekonstruktion der Landschafts- und Kulturgeschichte in der Region Palpa (S-Peru)

Der Projektverbund „Nasca: Entwicklung und Adaption archäometrischer Techniken zur Erforschung der Kulturgeschichte der Region Palpa / S-Peru“ umfasst ein Teilprojekt zur Anwendung der Radiokohlenstoff-Datierung auf die archäologischen Fundkomplexe dieser Region. Die Chronologie der Nasca-Kultur (etwa 200 vor bis 650 nach Chr.) und der vorangegangenen Paracas-Kultur (etwa 800 bis 200 vor Chr.), die in der Wüste zwischen den peruanischen Anden und dem Pazifik die weltberühmten Scharrbilder (Geoglyphen) angelegt haben, basierte bisher fast ausschließlich auf einer Keramik-Klassifikation ohne eine umfassende chronometrische Altersbestimmung. Im Rahmen der hier vorgestellten Arbeit wurde auf der Grundlage von über 100 14C-Datierungen an organischem Material aus Siedlungsresten und Grabfunden sowie Material im direkten Fundzusammenhang mit den Geoglyphen der Region Palpa eine erste numerische Chronologie der Paracas- und Nasca-Kultur erstellt. Das Hauptaugenmerk lag dabei auf den nahe Palpa gelegenen Siedlungszentren der Nasca, Los Molinos und La Muña, sowie auf den Paracas-zeitlichen Fundplätzen Pernil Alto und Jauranga. Im Zuge des Projektes wurde am Heidelberger Radiokohlenstoff-Labor eine Aufbereitungsanlage zur Herstellung von Graphit-Targets für AMS-Messungen (AMS = Beschleuniger-Massen-Spektrometer) aufgebaut. Die Anlage arbeitet semi-automatisch und wird mit dem eigens dafür entwickelten Steuerprogramm HAMSTER überwacht. Mit der AMS-Technik können 14C-Proben im Milli- oder Mikrogrammbereich datiert werden, was die Altersbestimmung von archäologischen Funden mit nur wenig organischem Material ermöglicht. So konnten erstmals die in Peru als Baumaterial weit verbreiteten Lehmziegel (Adobes) zur Datierung herangezogen werden. In Zusammenarbeit mit dem geomorphologischen Teil des Projektverbundes wurde an der Paläoklimarekonstruktion für die Region Palpa gearbeitet. Als Klimaarchive standen dabei die Flussterrassen des Rio St. Cruz, Rio Grande und Rio Palpa, ein Schlammstrom bei La Muña sowie Löss-Schnecken zur Verfügung, die mitunter nur mittels AMS-14C-Technik datiert werden konnten. Neben der zeitlichen Rekonstruktion des Beginns der Wüstenrand-lössbildung gelang der Nachweis einer Feuchtphase in der Region zwischen 1390 und 1714 cal AD, einer Zeit, die aufgrund globaler Gletschervorstöße als „Kleine Eiszeit“ bezeichnet wird

Geochemistry of last glacial sediments of Isla de los Estados, southeastern Tierra del Fuego

The island of Isla de los Estados is situated at 54.5°S, 64°W, east of Argentinian Tierra del Fuego, and is located in a sensitive geographic position in relation to the zonal circulation between Antarctica and South America. Its terrestrial records of the last deglaciation, recording atmospheric conditions but within an oceanic setting, can help to clarify changes of regional circulation patterns, both atmospheric and marine. Here, we present geochemical analyses from 16-10 ka cal BP of a peat core from Lago Galvarne Bog at the northern coast of the island, and a lake sediment core from Laguna Cascada 3 km further south. The data comprise TC, TN, loss on ignition analyses and continuous XRF scanning on both cores as well as age-depth modeling based on AMS-14C dating. Deglaciation and onset of peat formation in the coastal areas began before 16 ka cal BP followed by a rapid glacial retreat and the start of lacustrine sedimentation further inland. Data suggest initially windy conditions with permafrost succeeded by gradually warmer and wetter conditions until ca 14.5 ka cal BP. The warming trend slows down until ca 13.5 ka cal BP, followed by arid conditions culminating around 12.8 ka cal BP. Our data suggest fairly warm conditions and the establishment of denser peat and forest vegetation ca 10.6 ka cal BP, contemporaneous with the onset of the Antarctic thermal optimum. This indicates large-scale shifts in the placement of zonal flow and the Westerlies at the beginning of the Holocene

Deglacial environmental changes on Isla de los Estados (54.4°S), southeastern Tierra del Fuego

The island of Isla de los Estados is situated at 54.5 degrees S, 64 degrees W, east of Argentinian Tierra del Fuego, and is located in a sensitive geographic position in relation to the zonal circulation between Antarctica and South America. Its terrestrial records of the last deglaciation, recording atmospheric conditions but within an oceanic setting, can help to clarify changes of regional circulation patterns, both atmospheric and marine. Here, we present geochemical analyses from 16-10 ka cal BP of a peat core from Lago Galvarne Bog at the northern coast of the island, and a lake sediment core from Laguna Cascada 3 kin further south. The data comprise TC, TN, loss on ignition analyses and continuous XRF scanning on both cores as well as age-depth modeling based on AMS-C-14 dating. Deglaciation and onset of peat formation in the coastal areas began before 16 ka cal BP followed by a rapid glacial retreat and the start of lacustrine sedimentation further inland. Data Suggest initially windy conditions with permafrost succeeded by gradually warmer and wetter conditions until ca 14.5 ka cal BP. The warming trend slows down until ca 13.5 ka cal BP, followed by arid conditions culminating around 12.8 ka cal BP. Our data suggest fairly warm conditions and the establishment of denser peat and forest vegetation ca 10.6 ka cal BP, contemporaneous with the onset of the Antarctic thermal optimum. This indicates large-scale shifts in the placement of zonal flow and the Westerlies at the beginning of the Holocene. (C) 2008 Elsevier Ltd. All rights reserved