First discovery of cryptotephra in Holocene peat deposits of Estonia, eastern Baltic

This article reports the first discovery of middle Holocene cryptotephra from a peat sequence in Estonia, eastern Baltic. Two sequences, Mustjärve and Parika (located 110 km apart), were chosen for a pilot study aimed at finding traces of tephra fallout during the middle Holocene. Peat accumulation at both sites started in the early Holocene (c. 9500–9000 ¹⁴C yr BP; c . 11 000–10000 cal. yr BP) and continued throughout the whole Holocene. The radiocarbon-dated intervals between c. 2000 and 5000 ¹⁴C yr BP (c. 2000–5500 cal. yr BP) were chosen from both sites for the study. Colourless tephra shards were identified at 312–316 cm below the peat surface in the Mustjärve peat sequence, while no tephra was found in peat of the same age at Parika. Electron microprobe analyses suggest a correlation with the initial phase of the Hekla-4 eruption (c. 4260 cal. yr BP), although the age-depth model indicated an age around 4900 cal. yr BP. Small concentrations of colourless to light brown tephra shards at 266–270 cm in the Mustjärve sequence indicate that the Kebister tephra (c. 3750 cal. yr BP) might also be present, but geochemical analyses were not possible. The low concentration and small size of the tephra particles indicate that Estonian bogs are probably on the verge of where tephrochronology is possible in northwestern Europe. Further studies of full Holocene sequences are required in order to discover traces of other ash plumes reaching as far east as the eastern Baltic area.     

Is there a Nuclear Reactor at the Center of the Earth?

In this paper we discuss the Herndon hypothesis that a nuclear reactor is operating at the center of the Earth. Recent experimental evidence shows that some uranium can have partitioned into the core. There is no viable mechanism for the small amount of uranium that is dissolved in the molten metal to crystallize as a separate uranium phase (uranium metal or uranium sulfide) and migrate to the center of the core. There is no need for an extra heat source, as the total heat leaving the core can be easily provided by “classical” heat sources, which are also more than adequate to maintain the Earth’s magnetic field. It is unlikely that nuclear georeactors (fast breeder reactors) are operating at the Earth’s center.     

Enhanced Weathering: An Effective and Cheap Tool to Sequester Co2

Weathering and subsequent precipitation of Ca- and Mg-carbonates are the main processes that control the CO₂-concentration in the atmosphere. It seems logical, therefore, to use enhanced weathering as a tool to reduce rising CO₂-levels. This can be applied as a technology, by reacting captured CO₂ with olivine or calcium-silicates in autoclaves. It can also be applied extensively, by spreading fine-powdered olivine on farmland or forestland. Measures to control the CO₂-levels of the atmosphere will be adopted more readily if they also serve some broader economic goals. An effective strategy for CO₂ control will require many parallel approaches simultaneously.     

Holocene humidity fluctuations in Sweden inferred from dendrochronology and peat stratigraphy

Tree-ring and peat stratigraphy data were examined back to 5000 BC in order to identify and compare humidity changes in Fennoscandia. The temporal variation in distribution of Scots pine ( Pinus sylvestris L.) was used as a measure of past lake-level fluctuations in central Sweden. The chronology, which spans 2893 BC–AD 1998 with minor gaps in AD 887–907 and 1633–1650 BC and with additional floating chronologies back to 4868 BC, was cross-dated and fixed to an absolute timescale using a chronology from Torneträsk, northern Sweden. The peat stratigraphy from the Stömyren peat bog, south-central Sweden, was transformed into humification indices to evaluate humidity changes during the past 8000 years. The peat chronology is established by four tephra datings and eight ¹⁴C datings. Synchronous periods of drier conditions, interpreted from regeneration and the mortality pattern of pine, tree-ring chronology and peat humification, were recognized at c. 4900–4800 BC, 2400–2200 BC, 2100–1800 BC, 1500–1100 BC, AD 50–200, AD 400–600 and AD 1350–1500. Possible wetter periods were encountered at 3600–3400 BC, 3200–2900 BC, 2200–2100 BC, 1700–1500 BC, 1100–900 BC, 100 BC-AD 50, AD 200–400, AD 750–900 and AD 1550–1700. The wet and dry periods revealed by the tree rings and peat stratigraphy data indicate considerable humidity changes in the Holocene.     

Fluorine distribution in waters of Nalgonda District, Andhra Pradesh, India

Geochemical and hydrochemical studies were conducted in Nalgonda District (A.P.), to explore the causes of high fluorine in waters, causing a widespread incidence of fluorosis in the local population. Samples of granitic rocks, soils, stream sediments, and waters were analyzed for F and other salient chemical parameters. Samples from the area of Hyderabad city were analyzed for comparison. The F content of waters in areas with endemic fluorosis ranges from 0.4 to 20 mg/l. The low calcium content of rocks and soils, and the presence of high levels of sodium bicarbonate in soils and waters are important factors favoring high levels of F in waters.     

Deglaciation history of the southwestern Fennoscandian Ice Sheet between 15 and 13 14C ka BP

Analysis of 2D and 3D seismic records from the continental shelf off western Norway, in combination with chronological constraints from ¹⁴C dates, has led to a model for the glacial development in these shelf areas between c. 15 and 13 ¹⁴C ka BP. On the shallow Måløy Plateau adjacent to the Norwegian Channel, iceberg scours are preserved below a prominent moraine ridge, which by correlation to the Norwegian Channel indicate ice retreat at c. 15 ¹⁴C ka BP. Subsequently, the ice advanced across the scoured surface and deposited a till sheet before stabilizing to deposit a prominent moraine, termed the Bremanger Moraine. Based on location on the shelf, seismic stratigraphy, morphology and C dates the Bremanger Moraine is correlated with a significant moraine on the continental shelf off Trøndelag. We suggest that these features are products of a regional glacial event, the Bremanger Event, dated to <15–13.3 ¹⁴C ka BP. The Bremanger Event is probably a result of the deteriorating climatic conditions in the NE Atlantic during Heinrich event 1.     

Climate and environment on the Karelian Isthmus, northwestern Russia, 13000-9000 cal. yrs BP

Sediment sequences retrieved from Lake Medvedevskoye (60°13'N; 29°54'E) and Lake Pastorskoye (60°13'N; 30°02'E), Karelian Isthmus, northwestern Russia, were analysed for lithology, pollen and diatom stratigraphy, total organic carbon content and mineral magnetic parameters. Age control for both sequences was provided by AMS ¹⁴C measurements and the Vedde Ash tephra. The reconstructed climatic and environmental development shows the deglaciation of the sites and the establishment of sparse shrub and herb/grass vegetation before 12650 cal. yrs BP ('Allerød'; GI-1a). Steppe tundra and cold, dry conditions prevailed until about 11000 cal. yrs BP, i.e. throughout the 'Younger Dryas' (GS-1) and the earliest Holocene. The establishment of open Picea-Pinus-Betula forest around the lakes at about 11 000 cal. yrs BP coincides with the first distinct change towards gradually warmer and more humid climatic conditions. Boreal forest with Picea, Pinus, Betula, Alnus incana and Corylus was present at the lower altitude site between c. 10700 and 10200 cal. yrs BP, while open Betula-Pinus forest continued to dominate the vegetation around the higher altitude site. After a short, possibly colder, phase around 10200-10000 cal. yrs BP, which is expressed by a marked reduction in vegetation cover and decreased lake productivity, climatic conditions became significantly warmer and possibly more humid. Boreal forest with Pinus, Betula, Picea, Alnus incana, Corylus and Ulmus became widespread in the region after 10000 cal. yrs BP. The delayed environmental response of the lakes and their catchment to hemispheric warming at the Pleistocene/Holocene boundary may be explained by a sustained blocking of westerly air masses due to the presence of the Scandinavian ice sheet and associated strengthened easterlies and anticy-clonic circulation and/or extensive permafrost.     

The Hormuz Strait Dam Macroproject—21st Century Electricity Development Infrastructure Node (EDIN)?

Ocean gulfs offer a means of artificially creating a depression, which can be used for a regionally significant hydroelectric macroproject. We examine here the case for a dam at the Strait of Hormuz that blocks a large gulf situated in an arid region. A 35 m evaporation of this concentration basin will reduce its watery surface area by ∼53% and allow generation of ∼2.050 MW (or possibly ∼2.500 MW) of electricity. Our conclusion is that the proposed Electricity Development Infrastructure Node (EDIN) is a feasible and desirable macroproject. If the macroproject starts in the near-term future, it would require a significant change in the logistics of oil and gas transport from this region. Alternatively, it can be considered as an attractive future solution for the energy requirements of the region after exhaustion of its oil and gas reserves.     

Carbon,hydrogen, and oxygen isotope studies of the regional metamorphic complex at Naxos,Greece

At Naxos, Greece, a migmatite dome is surrounded by schists and marbles of decreasing metamorphic grade. Sillimanite, kyanite, biotite, chlorite, and glaucophane zones are recognized at successively greater distances from the migmatite dome. Quartz-muscovite and quartz-biotite oxygen isotope and mineralogie temperatures range from 350 to 700°C.The metamorphic complex can be divided into multiple schist-rich (including migmatites) and marblerich zones. The δ¹⁸O values of silicate minerals in migmatite and schist units and quartz segregations in the schist-rich zones decrease with increase in metamorphic grades. The calculated δ¹⁸O_H2O values of the metamorphic fluids in the schist-rich zones decrease from about 15‰ in the lower grades to an average of about 8.5‰ in the migmatite.The δD values of OH-minerals (muscovite, biotite, chlorite, and glaucophane) in the schist-rich zones also decrease with increase in grade. The calculated δD_H2O values for the metamorphic fluid decrease from ?5‰ in the glaucophane zone to an average of about ?70‰ in the migmatite. The δD values of water in fluid inclusions in quartz segregations in the higher grade rocks are consistent with this trend.Theδ¹⁸O values of silicate minerals and quartz segregations in marble-rich zones are usually very large and were controlled by exchange with the adjacent marbles. The δD values of the OH minerals in some marble-rich zones may reflect the value of water contained in the rocks prior to metamorphism.Detailed data on 20 marble units show systematic variations of δ¹⁸O values which depend upon metamorphic grade. Below the 540°C isograd very steep δ¹⁸O gradients at the margins and large δ¹⁸O values in the interior of the marbles indicate that oxygen isotope exchange with the adjacent schist units was usually limited to the margins of the marbles with more exchange occurring in the stratigraphic bottom than in the top margins. Above the 540°C isograd lower δ¹⁸O values occur in the interior of the marble units reflecting a greater degree of recrystallization and the occurrence of Ca-Mg-silicates.Almost all the δ¹³C values of the marbles are in the range of unaltered marine limestones. Nevertheless, the δ¹³C values of most marble units show a general correlation with δ¹⁸O values.The $\text{CO}{}_2\text{H}{}_2\text{O}$ mole ratio of fluid inclusions in quartz segregations range from 0.01 to 2. Theδ¹³C values of the CO₂ range from ?8.0 to 3.6‰ and indicate that at some localities CO₂ in the metamorphic fluid was not in carbon isotopic equilibrium with the marbles.     

Ghost crab burrow density at Watamu Marine National Park: An indicator of the impact of urbanisation and associated disturbance?

Ghost crab (Ocypode species) burrow densities have previously been used as an indicator of anthropogenic impact. This study aimed to assess the burrow density of Ocypode species (O. ryderi and O. cordimanus) at four sites across Watamu Marine National Park, Kenya. Two sites were in front of hotel complexes (denoting a high degree of urbanisation), and two were in front of residential housing among coastal scrub (denoting a low degree of urbanisation). The findings reveal significantly higher burrow densities at sites in front of residential housing, which was the less developed area. This provides further evidence that Ocypode burrow densities can be used, where other methods would be impractical, to estimate the impact of some human activities along beach fronts, such as at Watamu Marine National Park.