A sedimentation study of St. Ana Lake (Romania) applying the <Superscript>210</Superscript>Pb and <Superscript>137</Superscript>Cs dating methods

The biggest problem with most lakes that have no contact with other water sources and are being charged by precipitation is the massive eutrophication. The aim of this work was to determine the sedimentation rate in order to evaluate the progress of eutrophication for St. Ana Lake (Ciomad Mountain near the Băile Tuşnad in Harghita County (Romania)). The concentration of ²¹⁰Pb was determined by means of high resolution gamma spectrometry as well as derived from ²¹⁰Po activity which was measured through alpha spectrometry; values obtained are in good agreement. For the excess ²¹⁰Pb activity values between 4.0±0.5 Bq/kg and 218±20 Bq/kg have been found. As an alternative method, the ¹³⁷Cs dating method was applied as well. Calculated mass sedimentation rates are in the range of 0.06±0.01 to 0.32±0.05 g/cm² year with a mean of value of 0.15±0.02 g/cm² year. Linear sedimentation rates yielded much higher sedimentation values (between 0.5±0.1 and 7.9±0.7 cm/year with a mean of 2.4±0.6 cm/year), due to the predominant organic matter composition and the long suspension time of the sediment. This is an indication for the process of eutrophication which will probably lead to the transformation of the lake into a peat bog.     

Sedimentation rates in the Lake Qattinah using 210Pb and 137Cs as geochronometer

The constant rate of supply (CRS) of excess ²¹⁰Pb model was successfully applied to assess ²¹⁰Pb data of two sediment cores from the lake Qattinah, Syria. Gamma spectrometry was used to determine ¹³⁷Cs and ²¹⁰Pb activity concentrations. The bottom of the cores was ²¹⁰Pb-dated to years 1907 and 1893. The accumulation rates were determined using ²¹⁰Pb method and found to vary similarly in both cores from 0.10 ± 0.01 to 3.78 ± 0.57 kg m^?2 y^?1 during the past century. ¹³⁷Cs was used as an in-dependent chronometer. The two distinct peaks observed on the ¹³⁷Cs record of both cores, corresponding to 1965 and 1986, have allowed a successful validation of the CRS model.     

Sediment geochronology and spatio-temporal and vertical distributions of radionuclides in the Upper Bonny Estuary (South Nigeria)

Surface deposits and sediment cores were collected from the Upper Bonny Estuary, located in Southwest Nigeria, and analyzed to determine spatio-temporal and vertical distributions of radio-nuclide activities expressed in Bq·kg^?1 dry weight. The results of activities of naturally occurring radionuclides of ²²⁶Ra (15 ± 2–34 ± 3 Bq·kg^?1), ²²⁸Ra (32 ± 5–48 ± 6 Bq·kg^?1), ⁴⁰K (264 ± 29–462 ± 36 Bq·kg^?1) were found to be all within the range of typical values reported for coastal regions. Ratios of ²²⁶Ra to ²²⁸Ra suggested accretion for all samples with low sediment accumulation registered during rainy months. In addition, vertical distributions at the three sampling sites were also studied with the initial aim of establishing chronologies from the decay of excess ²¹⁰Pb. In two cores, excess ²¹⁰Pb, estimated by subtracting ²²⁶Ra from total ²¹⁰Pb on a layer-by-layer basis, exhibit relatively constant activity with discrete minima and maxima. Therefore, these cores were excluded from radiometric dating. Only the third core could be dated by the constant rate of supply model, and ¹³⁷Cs was utilized to validate the ²¹⁰Pb chronology.     

Estimation of soil erosion on cultivated fields on the hilly Meghalaya Plateau,North-East India

The estimation of soil erosion rates in complex subtropical agricultural systems of hilly environment is difficult and most of the traditional methods have serious limitations. The ¹³⁷Cs technique allows to obtain relatively quickly retrospective medium term soil erosion results. The objective of this study was using ¹³⁷Cs approach to quantify soil loss under agricultural system which develops under growing human pressure on the hilly terrain of the Meghalaya Plateau. The measured values of caesium inventory for all sampling points are between 2% and 63% of the reference value of caesium inventory. The estimated annual soil loss for sampling points located on the slope are between 29 and 79 Mg·ha⁻¹·yr⁻¹ in the case of an improved mass balance model. It means that soil erosion in this manually tilled agricultural area cannot be neglected.     

Caesium-137 as an indicator of geomorphic processes in a drainage basin system

Caesium-137 from fallout from nuclear weapons tests is adsorbed on fine sediments and becomes an effective tracer. It is hypothesised that within a drainage basin, sites undergoing little or no erosion accumulate ¹³⁷ Cs in their upper layers; cultivated soils will have ¹³⁷ Cs uniformly distributed within the cultivated layer; eroded soils, cultivated or not, will have relatively less ^l37 Cs, depending on the severity of erosion. Accumulated sediments will have characteristic ¹³⁷ Cs profiles reflecting temporal fallout variations and sedimentation history. This hypothetical model is largely confirmed by results from Maluna Creek basin, where erosion and accumulation of sediments has taken place. Soils under viticulture have about one third the ¹³⁷ Cs content of soils with grass cover, indicating more severe erosion under cultivation. Caesium-137 profiles in alluvial fan and flood plain deposits correlate with sediment layers and known cultivation history.     

Provenancing East Mediterranean cedar wood with the <Superscript>87</Superscript>Sr/<Superscript>86</Superscript>Sr strontium isotope ratio

⁸⁷Sr/⁸⁶Sr isotope ratios of cedar wood from forests in the East Mediterranean have been compiled in order to investigate the feasibility of provenancing archaeological cedar wood finds. Cedrus sp. forests furnished a great amount of wood in antiquity, for purposes ranging from ship to temple construction, and for fashioning cult statues and sarcophagi. The ⁸⁷Sr/⁸⁶Sr signatures of archaeological cedar samples may be compared with the preliminary dataset presented here to help determine the geographic origin of wooden artifacts. Sample sites include two forest areas in the Troodos Massif of Cyprus, five in the Lebanon, and two in Turkey’s Taurus Mountains. Sr ratios for wood varieties (i.e., early heartwood, late heartwood, sapwood, and twig wood) demonstrate relative uniformity between the xylem types frequently recovered from archaeological contexts. As such, this pilot study also assesses important issues of archaeological sampling and the geographical factors that influence Sr uptake in cedar trees of this region. While the regional signatures are distinct in most cases, small sample sizes and range overlap indicate the need for additional methods to make a case for a certain source forest. Alone, this method continues to be best used to disprove assumed wood provenances.     

The deserts of the Kashmir‐Tibetan frontier

Abstract

Semi-arid landscapes are vulnerable to cultivation, overgrazing and climate variability, although it is difficult to identify the relative significance of these three factors. In the South African Karoo, the ‘desertification debate' seeks to explain a change to more shrubby vegetation in heavily grazed areas. We examine these issues in catchments where farm reservoirs provide sediment stores with 137Cs, 210Pb, geochemical and mineral magnetic signatures. Rainfall data and stocking numbers are reported and current erosion rates are estimated. Sediment accumulation in the reservoirs increases between 1935 and 1940, probably due to rises in the frequency of rainfall events of >25mm day. Significant increases in sedimentation rates (×8) occur during rain-fed wheat cultivation. In an uncultivated catchment, sediment yields remain relatively high and reflect increases in erosion from hillslopes, colluvial storage, and cultivated land sources. Gully systems have acted as transport routes rather than sediment sources over the last ～70 years. Badland erosion rates average ca. 50t ha^?1 yr^?1. At Ganora, their development in the 1920s strongly influences peak sedimentation between 1970 and 1980. Any delay between badland initiation and increased sediment yield appears to be a function of landscape connectivity. Recovery following disturbance is occurring slowly and is likely to take >100 years. De-stocking and better management systems are reducing erosion rates but may be offset by increases in rainfall intensity.     

四、五世纪东亚世界的形成与东晋南朝——以中国史料为中心

Adopting the historical periodization and the “ethnic awakening” theory of Konan Naito, this essay discusses the early formation of East Asian states such as Koguryō, Paekche, Silla and Wa during the 4^th and 5^th centuries, as well as the political order within the East Asian society shaped by the enfeoffment of the Eastern Jin and the Southern dynasties by using Chinese sources. It argues that the cultural influences of the Qin and Han dynasties promoted the ethnic awakening of East Asian peoples, and during the turmoil periods of the Wei, the Jin, and the Division Era these ethnic groups leaped rapidly in their roads of state-formation. The enfeoffment system of the Eastern Jin played significant role in this process, and therefore set up the basic structure of the international relationship in early modern East Asia.     

Fallout 137Cs and natural 40K as tracers of topsoil development during slope processes — a case study from the Daugai environs, Southern Lithuania

Investigations of soil erosion by ¹³⁷Cs method brings uncertainties of different nature. The estimation of the ¹³⁷Cs local inventory is associated with problems of data comparison and instrumental errors. In order to avoid systematic errors, the rate of soil erosion determined by the ¹³⁷Cs method is compared with the values obtained for other radioactive elements. Soil parameters must be regarded too. The aim of the work was to test the character of ¹³⁷Cs and ⁴⁰K distribution in the topsoil vertical section for determination erosion-accumulation type and ratio in different time spans. The topsoil thickened by different types of erosion-accumulation processes was sampled at a 2–3 cm interval. Soil samples were analysed by means of scintillation gamma spectrometry. The relationship between ¹³⁷Cs and ⁴⁰K inventories was weakest in the topsoil formed by mixing of soil material during the installation of artificial drains. Based on climatic characteristics, variations of theoretical soil accumulation rate in the last 50 years were calculated for the topsoil accumulated predominantly by water erosion. ⁴⁰K and ¹³⁷Cs correlation in the bottom of vertical section of topsoil or arable horizon are closest and this section may be used as a complementary parameter determining the local inventory value.     

FINGERPRINTING OF ROMAN MINTS USING LASER‐ABLATION MC–ICP–MS LEAD ISOTOPE ANALYSIS*

In this paper we present data to demonstrate the applicability of laser‐ablation MC–ICP–MS isotope analysis to archaeological artefacts, in this case Roman silver coins. The technique requires no chemical preparation, does minimal damage to the sample and yields external reproducibility that is better than conventional TIMS analysis; ²⁰⁷Pb/²⁰⁶Pb =±0.015% 2σ in comparison with ²⁰⁷Pb/²⁰⁶Pb =±0.04% 2σ, respectively. We show that Pb isotope compositions give isotope fingerprints to mints despite the likely reworking of the metal during coin production.     

Satellite image analysis of changes in glacier cover in Canada's northern Mackenzie Mountain Range (1987–2017)

The state of a group of glaciers in the northern Mackenzie Mountains across the Yukon‐Northwest Territories border was investigated over a period of three decades, using Landsat TM and OLI imagery from 1987, 1994, 1999, 2004, 2013, and 2017 to examine changes in glacier extents. A thresholded red/shortwave infrared band ratio image was used to delineate glacier boundaries. The total area of 74 glaciers in the study area decreased from 52.78 ± 1.32 km² in 1987 to 24.89 ± 0.62 km² in 2017, a loss of 27.89 ± 1.39 km² or 52.8 ± 2.6%, with a mean rate of reduction of 1.8% · a^?1. Smaller glaciers experienced larger relative changes in area. In this study, the rates of reduction are high compared to decreases reported for other glaciers in the region in the late 20^th century. Based on linear extrapolation of the trend in values of total glacier area, it is predicted—subject to uncertainties in how glaciers diminish in size and eventually disappear—that the study area could be free of visible glacier cover within three decades.     

Estimation of Soil Erosion Using Field and Modelling Approaches in an Undisturbed Arnhem Land Catchment,Northern Territory,Australia

An assessment of slope erosion at Tin Camp Creek catchment, Arnhem Land, Northern Territory, Australia, was carried out using the fallout environmental radioisotope caesium‐137 (¹³⁷Cs) as an indicator of soil erosion status, two numerical models (SIBERIA and the Revised Universal Soil Loss Equation (RUSLE)) and erosion pins. This undisturbed drainage basin is situated in the seasonally wet‐dry tropics, with high energy storms and a mean annual rainfall of 1389 mm. Tin Camp Creek catchment is unaffected by European agriculture or pastoral activities, but often experiences fire during the dry season. Two transects were sampled for ¹³⁷Cs in 2002 and 2004, and two models were used to convert ¹³⁷Cs measurements into soil loss estimates. Two methods using the theoretical Profile Distribution Model (PDM) gave net soil redistribution rates between +2.72 and –22.19 t ha^?1 yr^?1 and +2.95 and –24.06 t ha^?1 yr^?1, respectively, while an Australian empirical model (AEM) for uncultivated soils produced estimates between +1.84 and –7.00 t ha^?1 yr^?1 (negative values indicate soil erosion, positive, deposition). The RUSLE gave estimated soil losses for the two transects of approximately 10 t ha^?1 yr^?1, while the SIBERIA model produced values between 0.5 and 2 t ha^?1 yr^?1 for the transects and between 3.5 and 11 t ha^?1 yr^?1 for the total catchment. Average net soil losses of 14 and 15 t ha^?1 yr^?1 for the total catchment and slopes, respectively, were measured by erosion pins. The soil losses in the catchment are similar to those for some other transects in the Northern Territory and the Kimberley region of Western Australia (measured by the ¹³⁷Cs AEM), even though these areas are affected by pastoral activities. This may be at least partly explained by erosion in Tin Camp Creek catchment during high intensity rainstorms at the commencement of the wet season, especially if the slopes have been affected by fire during the previous dry season.     

The variation in δ13C values in bone collagen for two wild herbivore populations: Implications for palaeodiet studies

The δ¹³C values for un-defatted bone gelatin of individual members of wild populations of mule deer (Odocoileus hemionus hemionus) and field vole (Microtus townsendii) have been measured to determine the variability within each population. Means and standard deviations for the mule deer sample (N=55) and vole sample (N=22) are −20·6±0·5‰ and −23·2±0·6‰, respectively. The distributions of δ¹³C values for each of these populations are normal and we observed no correlation in δ¹³C values with age or sex.     

Lake Nuga Nuga: a Levee‐dammed Lake in Central Queensland,Australia

Lake Nuga Nuga is a levee‐dammed lake in the dry sub‐humid tropics of the Fitzroy Basin in Central Queensland, Australia, that has expanded significantly since it was first mapped in 1866. ²¹⁰Pb dating of a sediment core from the lake indicates that the rate of sedimentation has been constant for the past 67 years at 3 mm yr^?1 despite widespread clearing and land use intensification in the catchment during that time. Pollen analysis confirms this and shows that there was little change in vegetation during the early settlement period (1863–1962), but the intensification of land use that started in the early 1960s brought about a dramatic change in the vegetation communities. This study demonstrates that while sediment production may be significantly impacted by land‐use activities, sediment delivery is primarily controlled by topography.     

The use of Caesium–137 to Assess Surface Soil Erosion Status in a Water–Supply Catchment in the Hunter Valley,New South Wales,Australia

In the absence of direct erosion measurements, the soil activity of the fallout radionuclide caesium–137 (¹³⁷Cs) offers an attractive tool for the estimation of long–term (approximately 45 years) net surface and minor rill soil erosion rates for hillslopes. A transect–based soil sampling technique was applied to one woodland and five grazed pasture hillslopes in the Williams River water–supply catchment in the Hunter Valley, New South Wales. An Australian regression model (SOILOSS) relating net soil loss from runoff–erosion plots to ¹³⁷Cs deficit in soils was used to calculate a weighted net surface and minor rill erosion rate for the six hillslopes. The net median surface erosion rates ranged between 0.00 and 0.64 t ha^–1yr^–1with the average median soil erosion rate of 0.19 t ha^–1 yr^–1(std. dev. = 0.23), indicating that these hillslopes were unlikely to be major sources of sediment to the catchment's waterways. Net soil loss rates were also shown to be low in comparison to Australia–wide data and comparable to hillslope data obtained elsewhere in the same region. Minimum and maximum error bounds were provided with each erosion rate to account for radionuclide detector count error. For one hillslope the estimated error due to detection was 1.34 t ha^–1yr^–1, while the remaining five hillslopes exhibited error of up to 0.41 t ha^–1yr^–1. Correlation analyses between the net soil loss rates and physical hillslope characteristics were non–significant.     

87Sr/86Sr: a New Discriminant for Provenancing Neolithic Porcellanite Artifacts from Ireland

Antrim porcellanite (thermally metamorphosed Tertiary laterite) was the most common raw material used in the production of stone implements during the Neolithic in Ireland and was worked at two localities in North Antrim: Tievebulliagh, near Cushendall and Brockley on Rathlin Island.Attempts have been made to provenance material from these two known sources, the most successful to date being the use of geochemical data (Sr and Yppm). Here we present a new geochemical discriminant—Sr isotopic data—which reveal that Tievebulliagh and Brockley porcellanites are distinctive. Present-day⁸⁷Sr/⁸⁶Sr ratios form two discrete groupings ranging from 0·705894±25–0·706443±24 at Tievebulliagh and 0·704088±27–0·704587±25 at Brockley. A coherent relationship between⁸⁷Sr/⁸⁶Sr and Sr (ppm) reiterates the use of Sr content as a discriminant and illustrates the geochemical variability of Sr between these two sources.Although this is a destructive technique,⁸⁷Sr/⁸⁶Sr represents the best discriminant to date for Antrim porcellanites and will enable definitive provenancing of porcellanite artifacts from Ireland with important archaeological implications.     

Heavy Metals in Sediments of the Upper Hawkesbury‐Nepean River

There is little published information on heavy metals in surficial sediments of the upper Hawkesbury‐Nepean River in central New South Wales, Australia. In the current investigation, the fine fraction (<62.5 µm) of 90 sediment samples taken from this section of the river was analysed by flame‐Atomic Absorption Spectroscopy for nine heavy metals (Ag, Cd, Pb, Zn, Cu Co, Fe, Ni and Mn) to determine background and enrichment. Sediment in the upper Hawkesbury‐Nepean River is not heavily polluted by heavy metals. Maximum enrichment over background for Ni and Ag, Cd, Pb, Zn, Cu and Mn is 3x, 5.7x, 6x, 6.7x, 12x and 13.6x, respectively. Mean heavy metal concentrations for this, the upper section of the river, are about half the mean values for the Hawkesbury River between Windsor and Broken Bay in the lower, estuarine section of the river. The highest Cu, Pb and Zn concentrations (214, 108 and 334 mg kg^?1, respectively) occur in surficial sediments in Peachtree Creek at Penrith and the Nepean River near Jacksons Lane, Castlereagh. These metal concentrations are possibly associated with industrial activity at Penrith. Two of the six sewage treatment plants on the upper Hawkesbury‐Nepean River are associated with high metal concentrations (Cu, Zn, Fe and Mn) in sediments, that is, the West Camden and Penrith sewage treatment plants. Other possible sources of heavy metals are coal mining and washing which occurs at several places in the upper catchment. The highest Cd, Co and Fe concentrations (1.7, 27.6 mg kg^?1 and 4.81%, respectively) were found in sediments 400 m downstream of the Nepean Dam and the highest concentrations of Ni and Mn (54 and 790 mg kg^?1, respectively) were located in sediment from the Nepean River at Moresby Hill Road Bridge, near Robertson and at the Avon Dam Road Bridge. The source of these metals is unknown.     

An Examination of Vertical Accretion of Floodplain Sediments in the Labasa River Sugarcane Belt of Northern Fiji: Rates,Influences and Contributing Processes

The ¹³⁷Cs (caesium‐137) method was used to investigate medium‐term rates of sediment deposition on the floodplain of the Labasa River, on Vanua Levu island in northern Fiji. The Labasa basin is commercially important for sugarcane farming, which provides much revenue and sustains the economy in the greater Labasa area. Alluvium was sampled at three riverbank sites in vertical increments of 30 mm. Measured net vertical accretion rates, based on analysis of depth‐profiles of ¹³⁷Cs activity, ranged from 10 mm yr^?1 at a low‐lying site near a tributary confluence with the main river, to 60 mm yr^?1 on a levée that was elevated slightly above the adjacent floodplain. These rates of accretion are high, but in general agreement with rates recorded using similar methods in other tropical Pacific island river systems. Soil erosion under sugarcane on hilly parts of the lower Labasa basin is an important factor in rapid floodplain development. Observations made during Cyclone Ami, which traversed Vanua Levu island in early 2003, illustrate the major contribution of severe storm events to floodplain sediment supply, by triggering numerous landslides on catchment slopes and in‐channel debris floods, and by generating large‐magnitude overbank floods.     

New radiometric ages for the Early Upper Palaeolithic type locality of Brno-Bohunice (Czech Republic): comparison of OSL,IRSL, TL and C dating results

New radiometric data are reported from the recent excavation of the type locality of the Early Upper Palaeolithic entity of the Bohunician. Recently obtained radiocarbon (¹⁴C) data on charcoal are compared with new Optically Stimulated Luminescence (OSL) dating of sediment. OSL ages were determined on sediment from the archaeological occupation at Brno-Bohunice, as well as from the over- and underlying loessic sediments. Multiple techniques were applied, which all gave congruent results. While a dual protocol (post IR-OSL) failed the quality criteria tests, ages were obtained by Multiple-Aliquot-Additive-Dose (MAAD) on polymineral material and Single-Aliquot-Regeneration (SAR) on fine grain quartz extract as well as on polymineral material. Fading tests show significant loss of Infrared Stimulated Luminescence (IRSL) after storage for 3 and 12 months for one sample, but little or no fading for others. The resulting (uncorrected) age estimates are smaller than those on quartz by OSL methods. The latter are considered to be more reliable estimates of the sedimentation age of these deposits. The measured OSL doses do not show a simple distribution and the lowest 5% was used for age calculation to represent the most likely sedimentation age. The quartz from the loess overlying the archaeological layer is OSL dated to 30.9 ± 3.1 ka, while the sediment for the paleosol which contains the archaeological layer gave an age of 58.7 ± 5.8 ka. The attribution of this paleosol to the Hengelo interstadial is therefore questionable. However, if the Hengelo interstadial is correlated with the Dansgaard/Oeschger (D/O) event 12, statistical agreement within 2-σ is achieved. The OSL result for the archaeological layer is in accordance with a weighted average TL date on heated flint artifacts of 48.2 ± 1.9 ka from this layer as well as calibrated radiocarbon data (CalPal Hulu 2007) from nearby locations. However, radiocarbon data on charcoal samples obtained during excavation at Brno-Bohunice 2002 provide age estimates between 30 and 40 ka ¹⁴C-years, which translate to approximately (33) 35–44 ka on the calendric time scale according to the Hulu 2007 model. For the underlying loess a depositional age of 104.3 ± 10.6 ka was obtained by OSL. The presented OSL ages indicate that a simple correlation of soil sequences between sites within a region has to be verified by chronometric dating.     

Stable carbon and nitrogen isotope ratios of bone collagen: Variations within individuals,between sexes,and within populations raised on monotonous diets

The stable carbon and nitrogen isotope ratios of collagen of seven bones from each of three rabbits raised on a monotonous diet, and of two bones from each of eight female and seven male mink raised on another monotonous diet, were determined. The ranges of δ¹³C values and δ¹⁵N values were 0·5‰ and 0·6‰ for the rabbit bones and 1·0‰ and 1·4‰ for the mink bones. Uncertainties in the δ¹³C and δ¹⁵N values for prehistoric human diets estimated from the isotopic composition of collagen from the small numbers of bones which are typically available for analysis, and thus likely to be of the order of ±1‰.