Search results

Can a climate-triggered export of old contaminants from the soil alter the lead (Pb) contaminant burden of subarctic lakes? To address this question, we reconstructed the pollution history of three high latitude lakes situated in a region where a recent climatic shift has occurred. Dated sediment records were used as archives of past Pb inputs to the lakes, where the difference in the (206)Pb/(207

The relationship between climatic variations, vegetation dynamics and early human activity between c. 4150-2860 BC was reconstructed from a high-resolution pollen and geochemical record obtained from a small lake located in County Sligo, Ireland. The proxy record suggests the existence of a woodland with a largely closed canopy at the start of the fourth millennium BC. Only minor human disturbance

Changes in solar activity have previously been proposed to cause decadal- to millennial-scale fluctuations in both the modern and Holocene climates(1). Direct observational records of solar activity, such as sunspot numbers, exist for only the past few hundred years, so solar variability for earlier periods is typically reconstructed from measurements of cosmogenic radionuclides such as Be-10 and

Oxygen (delta O-18) and carbon (delta C-13) isotope records of calcitic carbonate components (Chara sp. algal encrustations and Bithynia tentaculata gastropod opercula) from a lake-sediment succession on the Baltic Sea island of Gotland, south-eastern Sweden, have been obtained to investigate regional climate dynamics during the Holocene. The hydrological sensitivity of the small lake, particularl

We have analyzed an almost 14,000 year old peat sequence on the island of Isla de los Estados (55 degrees S. 64 degrees W), east of Tierra del Fuego, in the core of the Southern Hemisphere Westerlies. A multitude of methods have been used: high resolution C-14 dating; detailed lithologic descriptions including humification degree; loss on ignition; magnetic susceptibility; bulk density; pollen and

We present a synthesis of the results of a multiproxy, multisite, palaeoecological study of Holocene environmental change in Kamchatka, Far East Russia, details of which are presented elsewhere in the volume. We summarise the results of the analyses of pollen, diatom, chironomid, and testate amoebae assemblages, together with stable isotopes of oxygen and carbon, and sediment characteristics from

A sediment sequence was taken from a closed, high altitude lake (informal name Olive-backed Lake) in the central mountain range of Kamchatka, in the Russian Far East. The sequence was dated by radiocarbon and tephrochronology and used for multi-proxy analyses (chironomids, pollen, diatoms). Although the evolution of Beringian climate through the Holocene is primarily driven by global forcing mecha

A sediment record from a small lake in the north-eastern part of the Kamchatka Peninsula has been investigated in a multi-proxy study to gain knowledge of Holocene climatic and environmental change. Pollen, diatoms, chironomids and selected geochemical parameters were analysed and the sediment record was dated with radiocarbon. The study shows Holocene changes in the terrestrial vegetation as well

Although satellite-based sensors have made vegetation data series available for several decades, the detection of vegetation trend and change is not yet straightforward. This is partly due to the scarcity of available change detection algorithms suitable for identifying and characterizing both abrupt and non-abrupt changes, without sacrificing accuracy or computational speed. We propose a user-fri

Holocene records of cellulose-inferred lake-water delta O-8 were produced from two lake-sediment sequences obtained in central and northern Kamchatka, Russian Far East. The sediment records share similar fluctuations in delta O-8 during the interval of ca. 5000-800 cal yr BP that correspond (inversely) with changes in K+ content of the GISP2 ice-core record from Greenland, a proxy for the relative

A radiocarbon and tephra-dated sediment core from Lifebuoy Lake, located on the north-east coast of Kamchatka Peninsula, was analysed for pollen, spores, diatoms, chironomids and tephra in order to uncover regional environmental history. The 6500-year environmental history of Lifebuoy Lake correlates with the broad regional patterns of vegetation development and climate dynamics with both diatoms

Pollen and sediment stratigraphic analyses of a transect of core sequences are used to reconstruct Holocene lake-level changes in Lake Igelsjon, southern Sweden. The pattern of changes seen in the records is related to climatic/hydrological changes and agrees principally with the pattern characteristically found in lakes in southern Sweden. However, compared with an earlier study based on isotopic

The C-14 dating method is the cornerstone for inferring age estimates for natural archives covering the last 50 000 yrs. However, C-14 age calibration for the last ice age relies mostly on records that only indirectly reflect the atmospheric C-14 concentrations. In consequence, calendar age estimates are significantly more uncertain for the period of the last ice age compared to the past 14000 yrs

Changes in the tropical hydrological cycle have been recorded world wide in speleothem records dating back more than 200,000 years for some areas. Numerous empirical and modelling studies have demonstrated a strong link between the intensity of the northern hemisphere monsoon and the precessional insolation cycle (similar to 23 ka (thousand years)). Here we present simulations of the climate condi

This study explores the relationship between land-use and floristic diversity between 600 BC and AD 2008 in the uplands of southern Sweden. We use fossil pollen assemblages and the Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) model to quantitatively reconstruct land cover at a regional scale. Floristic richness and evenness are estimated using palynological richness and RE

Aim To assess statistically the relative importance of climate and human impact on forest composition in the late Holocene. Location Estonia, boreonemoral Europe. Methods Data on forest composition (10 most abundant tree and shrub taxa) for the late Holocene (5100-50 calibrated years before 1950) were derived from 18 pollen records and then transformed into land-cover estimates using the REVEALS v

We present here surface water vapor isotopic measurements conducted from June to August 2010 at the NEEM (North Greenland Eemian Drilling Project) camp, NW Greenland (77.45 degrees N, 51.05 degrees W, 2484 m a.s.l.). Measurements were conducted at 9 different heights from 0.1m to 13.5m above the snow surface using two different types of cavity-enhanced near-infrared absorption spectroscopy analyze

Here, we present results from the most comprehensive compilation of Holocene peat soil properties with associated carbon and nitrogen accumulation rates for northern peatlands. Our database consists of 268 peat cores from 215 sites located north of 45 degrees N. It encompasses regions within which peat carbon data have only recently become available, such as the West Siberia Lowlands, the Hudson B