bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of post‐mixing chemical reactions on the major ion chemistry of bulk meltwaters draining the haut glacier d'arolla, valais, Switzerland
Authors: Brown G. H. , Sharp M. J. , Tranter M. , Gurnell A. M. , Nienow P. W.
Published: February 2007

Until now, alpine glacial meltwaters have been assumed to consist of two components, dilute quickflow and concentrated delayed flow, the mixing of which has been regarded as chemically conservative for the major dissolved ions and electrical conductivity. Dye tracing results suggest that this two‐component model adequately represents the sub‐glacial hydrology of the Haut Glacier d'Arolla, Switzerland. However, laboratory dissolution experiments in which various concentrations of glacial rock flour are placed in dilute solutions show that this rock flour is highly reactive and suggest that bulk meltwaters may acquire significant amounts of solute through rapid chemical reactions with suspended sediment which occur after mixing of the two components. This view is supported by detailed analysis of variations in the hydrochemistry of meltwaters draining from the Haut Glacier d'Arolla over three diurnal cycles during the 1989 melt season. Variations in the composition of bulk meltwaters are controlled by two main factors: dilution of the delayed flow component by quickflow, and the extent of post‐mixing reactions. The latter depends on the suspended sediment concentration in bulk meltwaters and on the duration of contact between these waters and suspended sediment. Seasonal changes in the magnitude of these factors result in changes in the character and causes of diurnal variations in meltwater chemistry. In June, these variations reflect discharge‐related variations in residence time within a distributed subglacial drainage system; in July, when a channelized drainage system exists beneath the lower glacier, they primarily reflect the dilution of delayed flow by quickflow; in August, when suspended sediment concentrations are particularly high, they reflect varying degrees of solute acquisition by post‐mixing reactions with suspended sediment that take place in arterial channels at the glacier bed.
Modelling sediment transport in stream channels in the arid zone of India
Authors: Sharma K. D. , Murthy J. S. R.
Published: February 2007

Ephemeral channels in arid regions convey larger amounts of sediment than perennial channels in humid regions. Sediment graphs at the outlet of channels have been derived by the standard sediment rating curve technique and by a lumped model based on the instantaneous unit sediment graph (IUSG) concept. The IUSG gives estimates of sediment transport that are better than those derived with the sediment rating curve as it takes into account the availability of erodible material within the channel bed.
Mapping waterlogging of soils using digital terrain models
Authors: Merot Ph. , Ezzahar B. , Walter C. , Aurousseau P.
Published: February 2007

Maps of the potential waterlogging of soils were generated using hypotheses about the effect of topography on the soil water regime inspired by Beven and Kirkby's concept of saturation overland flow. The procedure was validated by comparing the simulated maps with maps derived from a 1: 25 000 soil survey for two contrasting catchments. The value and limitations of the method are discussed in the light of this comparison. The approach proposed here is relevant to modelling the distribution of intensely waterlogged soils, provided the relationship between bedrock and the limit values is established. This approach can be used for several purposes: (1) to distinguish positional waterlogging from other types of waterlogging; (2) to control the quality and consistency of waterlogging maps; and (3) to create soil water regime maps for non‐surveyed catchments. Conversely, soil water regime maps can be compared with contributing areas simulated by hydrological distributed models for validation purposes.
Dynamics of phosphorus compounds in a lowland river system: Importance of retention and non‐point sources
Authors: Svendsen Lars M. , Kronvang Brian , Kristensen Peter , Græsbøl Peter
Published: February 2007

Intensive measurements of the fluxes of phosphorus (P) and of P retention were carried out in a Danish lowland watershed (Gjern Å) during two hydrological years (June 1987 to May 1989). Seasonal and short‐term variations of P concentrations were measured by intensive automatic sampling covering P fluxes from the entire Gjern Å watershed and two subcatchments: the Gelbæk and Lake Søbygård. Moreover, infrequent sampling was performed in all major tributaries of the river system. Transport of P compounds (dissolved and particulate P) exposed a seasonal pattern which was highly affected by flow conditions, instream processes, as well as point and non‐point sources. Stormflow P transport during the two study years (1987‐8 and 1988‐9) constituted 56 and 61% in the Gelbæk, respectively, compared with 25 and 23% in the Gjern Å, respectively. Particulate P transport in the Gelbæk constituted 56 and 75% of annual total P transport during the two years compared with 77 and 75% in the Gjern Å. The magnitude of monthly baseflow and stormflow total P loads was significantly correlated with the mean monthly discharge during baseflow and stormflow in the Gelbæk, whereas only stormflow loads were correlated to discharge in the Gjern Å. In situ measurements of retention showed that the maximum amount of P stored in the Gelbæk during summer (June to August) was 22gPm−2 (1988) compared with 27gPm−2 (1987) in the Gjern Å. Lake Søbygård was a P source during summer but a P sink during winter and on an annual basis the net P released was 810 and 1420 kg, which corresponded to 7 and 20% of the annual P export from the watershed, respectively. Retention constituted about 30% of gross P transport in the Gelbæk during summer compared with 20% in the Gjern Å. Resuspension of retained P during stormflows in September 1987 constituted 94% of the stormflow P transport and 54% of the total P transport. Monthly total P and dissolved reactive P (DRP) mass balances for the main channel of the Gjern Å revealed a significant DRP retention over 17 months (p < 0.05) caused by P adsorption on sediments and biological uptake. On an annual basis the main channel was a sink of DRP (1220 and 1660 kg P) but a source of total P (3440 and 1000 kg P). implying that the channel is an important source of particulate P. Bank erosion proved to be a significant P source in the main channel of Gjern Å, whereas P delivery from soil erosion was possibly of minor importance. The annual non‐point P export from two intensively sampled catchments was significantly higher (0.89 and 0.45 kg Pha−1 yr−1) than from the five extensively sampled subbasins (0.43 and 0.17 kg Pha−1 yr−1). No significant relationship could be established between non‐point P export and the proportion of arable land and soil type. Only for the wet year of 1987‐8 was a significant relationship established between non‐point P export and the P load from scattered dwellings outside sewage areas in five subbasins.
Scale: Landscape attributes and geographical information systems
Authors: Band L. E. , Moore I. D.
Published: February 2007

The roles and limitations of geographical information systems (GISs) in scaling hydrological models over heterogeneous land surfaces are outlined. Scaling is defined here as the extension of small‐scale process models, which may be directly parameterized and validated, to larger spatial extents. A process computation can be successfully scaled if this extension can be carried out with minimal bias. Much of our understanding of land surface hydrological processes as currently applied within distributed models has been derived in conjunction with ‘point’ or ‘plot’ experiments, in which spatial variations and patterns of the controlling soil, canopy and meteorological factors are not defined. In these cases, prescription of model input parameters can be accomplished by direct observation. As the spatial extent is expanded beyond these point experiments to catchment or larger watershed regions, the direct extension of the point models requires an estimation of the distribution of the model parameters and process computations over the heterogeneous land surface. If the distribution of the set of spatial variables required for a given hydrological model (e.g. surface slope, soil hydraulic conductivity) can be described by a joint density function, f(x), where x = x1, x2, x3,… are the model variables, then a GIS may be evaluated as a tool for estimating this function. In terms of the scaling procedure, the GIS is used to replace direct measurement or sampling of f(x) as the area of simulation is increased beyond the extent over which direct sampling of the distribution is feasible. The question to be asked is whether current GISs and current available spatial data sets are sufficient to adequately estimate these density functions.
Process controls and similarity in the us continental‐scale hydrological cycle from eof analysis of regional climate model simulations
Authors: Famiglietti J. S. , Braswell B. H. , Giorgi F.
Published: February 2007

The surface hydrological output of a regional climate model is investigated with implications for process controls on the spatial‐temporal variability of the water cycle over the continental USA. Principal component analysis was performed on the seasonal and annual hydrological cycles to determine their dominant modes of spatial variability. At both seasonal and annual time‐scales, the first principal component is dominated by precipitation, which controls seasonal wetness and evaporation and accounts for only 52 to 58% of the variability in the continental‐scale hydrological cycle. The second principal component is related to both snowmelt runoff and the time variability of weather (via its influence on the residence time of soil moisture near the land surface) and explains another 22% to 34% of the variability in the hydrological cycle. Based on these findings, a classification of hydroclimatological similarity is proposed in which two areas are similar in their hydroclimatology if their first and second principal components are similar. The classification scheme differs from classical approaches because it is based on dominant modes of variability rather than specific indices such as vegetation or seasonal wetness.
Stream network morphology and storm response in humid catchments
Authors: Troch Peter A. , De Troch Francois P. , Mancini Marco , Wood Eric F.
Published: February 2007

Addressing scaling issues in hydrological modelling involves, among other things, the study of problems related to hydrological similarity between catchments of different scales. Recent research about catchment similarity relationships is based on distributed conceptual models of surface runoff production. In this type of hydrological modelling both infiltration excess and saturation excess runoff production mechanisms are considered. In many humid lowland areas overland flow is a rare phenomenon because of the specific conditions that prevail: moderate rainfall, high infiltration capacity and low relief. The complete drainage system in these regions consists of surface and subsurface components which have organized themselves in a given geological, geomorphological and climatic situation. A surface drainage network has developed through sapping erosion at the zone of groundwater exfiltration. The resulting hierarchical stream network is in equilibrium with large time‐scale conditions and adjusts itself dynamically to the inter‐year and seasonal meteorological fluctuations. Greater understanding of the interrelationships that underlie the storm response of catchments in humid lowland regions can be expected by focusing on stream network morphology as a function of topography, geology and climate. This paper applies the physically based mathematical model of stream network morphology, developed by De Vries (1977), to the Zwalmbeek catchment, Belgium. Based on this model and for different climatic conditions (expressed in terms of rainfall characteristics) the first‐order stream spacing versus average water‐table depth relationship is calculated. From field observations, digital elevation model derived channel network drainage densities and flood event analysis it is concluded that the 1% exceedance probability rainfall can be suggested as representative for the shaping climatic conditions in the catchment under study. The corresponding curves relating channel network characteristics, such as stream spacing, drainage density and channel geometry, to average water‐table depth are basin descriptors and could be used for comparative studies (e.g. regional flood frequency analysis). The model further allows for the prediction of the expansion and shrinkage of the first‐order channel network as a function of catchment wetness expressed in terms of the effective water‐table depth.
Global atmospheric water balance and runoff from large river basins
Authors: Oki Taikan , Musiake Katumi , Matsuyama Hiroshi , Masuda Kooiti
Published: February 2007

Atmospheric vapour flux convergence is introduced for the estimation of the water balance in a river basin. The global distribution of vapour flux convergence, ‐ ΔH · Q is estimated using the European Centre for Medium‐Range Weather Forecasts global analysis data for the period 1980‐1988. From the atmospheric water balance, the annual mean ‐ ΔH · Q can be interpreted as the precipitation minus evaporation. The estimated ‐ ΔH · Q is compared with the observed discharge data in the Chao Phraya river basin, Thailand. The mean annual values are not identical, but their seasonal change corresponds very well. The four year mean ‐ ΔH · Q is also compared with the climatological runoff of nearly 70 large rivers. The multi‐annual mean runoff is calculated from the Global Runoff Data Centre data set and used for the comparison. There is generally a good correspondence between the atmospheric water balance estimates and the runoff observations on the ground, especially in the mid‐ and high latitudes of the northern hemisphere. However, there are significant differences in many instances. The results emphasize the importance of accurate routine observations in both the atmosphere and river runoff. The global water balance of the zonal mean is compared with prior estimates, and the estimated value from this study is found to be smaller than previous estimates. The annual water balance in each ocean and each continent are also compared with previous estimates. Generally, the global runoff estimation using the conventional hydrological water balance is larger than the result by the atmospheric water balance method. Annual freshwater transport is estimated by atmospheric water balance combined with geographical information. The results show that the same order of freshwater is supplied to the ocean from both the atmosphere and the surrounding continents through rivers. The rivers also carry approximately 10% of the global annual freshwater transport in meridional directions as zonal means.
Scaling snowdrift development rate
Authors: Lever J. H. , Haehnel R.
Published: February 2007

For successful snowdrift modelling, measured drift shapes should be geometrically similar to full‐scale shapes and develop at rates that scale in a known manner. Consensus exists on most modelling methods and the similitude requirements needed to meet these objectives. A notable exception is the manner to scale drift development rates. A rationale is presented for rate scaling based on an independent model and prototype mass transport measurements. This approach is validated by comparing the rate of drift development for a model Wyoming snow fence with corresponding field data. This method yields excellent agreement, whereas the alternatives differ substantially.
Sesquiterpene lactone parthenolide suppresses tumor growth in a xenograft model of renal cell carcinoma by inhibiting the activation of NF‐κB
Authors: Oka Daizo , Nishimura Kazuo , Shiba Masahiro , Nakai Yasutomo , Arai Yasuyuki , Nakayama Masashi , Takayama Hitoshi , Inoue Hitoshi , Okuyama Akihiko , Nonomura Norio
Published: February 2007

The transcription factor nuclear factor‐κB (NF‐κB) has been shown to be constitutively activated in various human malignancies, including leukemia, lymphoma and a number of solid tumors. NF‐κB regulates the transcriptional of genes important for tumor invasion, metastasis and chemoresistance. The sesquiterpene lactone parthenolide, an inhibition of NF‐κB, has been used conventionally to treat migraines and inflammation. In this study, renal cancer cell lines OUR‐10 and ACHN were used for in vitro experiments to evaluate growth‐inhibitory effects of parthenolide. An OUR‐10 xenograft model in nude mice was also used to investigate the in vivo growth‐inhibitory effects of parthenolide. Apoptosis in response to treatment of OUR‐10 cells with parthenolide was confirmed. Localization of NF‐κB in response to parthenolide treatment was examined of by immunofluorostaining of OUR‐10 cells with antibody against NF‐κB p65 and by Western blot analysis of OUR‐10 cell and tumor nuclear and cytosol fraction. Parthenolide effectively inhibited proliferation of cultured OUR‐10 cells and triggered apoptosis in vitro. Subcutaneous injection or oral administration of parthenolide showed significant tumor growth inhibition in the xenograft model via decreased production of interleukin‐8 (IL‐8) or vascular endothelial growth factor (VEGF). Immunohistochemistry and Western blot analysis showed decreased nuclear localization of NF‐κB and phosphorylated NF‐κB protein and subsequently expression of MMP‐9, Bcl‐xL and Cox‐2 in response to parthenolide treatment. These results indicate that parthenolide is a useful in the treatment of renal cell carcinoma and acts via inhibition of NF‐κB. © 2007 Wiley‐Liss, Inc.
Selective induction of apoptosis by leptomycin B in keratinocytes expressing HPV oncogenes
Authors: Gray Lindsey J. , Bjelogrlic Predrag , Appleyard Virginia C.L. , Thompson Alastair M. , Jolly Carol E. , Lain Sonia , Herrington C. Simon
Published: February 2007

Human papillomavirus (HPV) infection is strongly associated with the development of anogenital neoplasia, particularly cervical cancer. It has been estimated that 99.7% of all cervical carcinomas are attributable to infection with HPV, and types 16 and 18 account for the vast majority of such cases. Both of these ‘high risk’ HPV types encode the oncoproteins E6 and E7, which exert multiple effects on many proteins involved in cell‐cycle regulation, including p53. The nuclear export protein inhibitor leptomycin B (LMB) has been shown to cause the nuclear sequestration of p53 in cervical carcinoma cells. We demonstrate that LMB induces apoptosis selectively at nanomolar concentrations in primary human keratinocytes (PHKs) expressing HPV oncogenes. Both monolayer and organotypic raft cultures of transduced PHKs were highly susceptible to treatment with LMB. By contrast, although LMB stimulated p53 accumulation in normal PHKs, no significant induction of apoptosis was detected on Western blots or immunostained monolayer/raft cells, or following pulsed exposure to the drug. Furthermore, topical application of μM concentrations of LMB to mouse skin was non‐toxic. These data suggest that the topical application of LMB to HPV‐infected intra‐epithelial lesions may represent a specific and effective therapeutic strategy against HPV‐associated anogenital neoplasia. © 2007 Wiley‐Liss, Inc.
Investigation of 3,4‐methylenedioxybenzene methoxyl methacrylate as coinitiator and comonomer for dental application
Authors: Shi Suqing , Nie Jun
Published: February 2007

In this study, 3,4‐methylenedioxybenzene methoxyl methacrylate (MDBMM) was synthesized for the purpose of replacing both triethylene glycol dimethacrylate (TEGDMA) and tertiary amine, which was usually used as a comonomer and coinitiator for dental resin, respectively. Urethane dimethacrylate (UDMA) was chosen as a monomer. Real time near Fourier transform infrared (FTIR) with a horizontal sample holder and dynamic mechanical analyzer (DMA) were used to study the kinetics and mechanical properties, respectively. The results showed that the addition of MDBMM as a coinitiator in UDMA/TEGDMA/CQ (70/30/0.5 wt %) system led to the increase of the rate of polymerization. When compared with the commercial polymerizable amine, 2‐(N,N‐dimethyl amino)ethyl methacrylate (DMEM), MDBMM showed comparable initiating reactivity and led to higher modulus around human body temperature (37°C). MDBMM as a comonomer resulted in slightly higher final double bond conversion than that of TEGDMA, which brought higher modulus around 37°C. Therefore, MDBMM can be used as both potential coinitiator and comonomer for dental application. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Modeling hydrogen evolution from the Fe4S4 and Fe8S9X (X = N, C) clusters. Can a FeS high‐spin cluster serve as a surrogate for the FeMo cofactor?
Authors: Mckee Michael L.
Published: February 2007

A high‐spin model of nitrogenase with a Fe8S9X+ cluster (X = nitrogen or carbon) is used to test a mechanism for molecular hydrogen production, which is known to accompany ammonia production. The reaction proceeds with a series of protonation‐reduction (PR) steps which are considered to be spontaneous if the calculated hydrogen‐cluster bond energy exceeds 35–40 kcal/mol. The novel features of this mechanism include the opening of the cluster when one of the bridging sulfides undergoes two PR steps and the direct participation of the central atom when it undergoes a PR step. After the sixth PR step, a cluster is formed which has a low barrier for loss of molecular hydrogen in an exothermic reaction step. The central atom (nitrogen or carbon) has only a minor effect on the reaction steps. © 2007 Wiley Periodicals, Inc. J Comput Chem 2007
Theoretical study on the Br + CH3SCH3 reaction
Authors: Zhang Hui , Zhang Gui‐Ling , Wang Li , Liu Bo , Yu Xiao‐Yang , Li Ze‐Sheng
Published: February 2007

The multiple‐channel reactions Br + CH3SCH3 → products are investigated by direct dynamics method. The optimized geometries, frequencies, and minimum energy path are all obtained at the MP2/6‐31+G(d,p) level, and energetic information is further refined by the G3(MP2) (single‐point) theory. The rate constants for every reaction channels, Br + CH3SCH3 → CH3SCH2 + HBr (R1), Br + CH3SCH3 → CH3SBr + CH3 (R2), and Br + CH3SCH3 →CH3S + CH3Br (R3), are calculated by canonical variational transition state theory with small‐curvature tunneling correction over the temperature range 200–3000 K. The total rate constants are in good agreement with the available experimental data, and the two‐parameter expression k(T) = 2.68 × 10−12 exp(−1235.24/T) cm3/(molecule s) over the temperature range 200–3000 K is given. Our calculations indicate that hydrogen abstraction channel is the major channel due to the smallest barrier height among three channels considered, and the other two channels to yield CH3SBr + CH3 and CH3S + CH3Br are minor channels over the whole temperature range. © 2007 Wiley Periodicals, Inc. J Comput Chem 2007
Measuring perceived community support: Factorial structure, longitudinal invariance, and predictive validity of the PCSQ (perceived community support questionnaire)
Authors: Herrero Juan , Gracia Enrique
Published: February 2007

Social support from intimate and confiding relationships has received a great deal of attention; however, the study of the community as a relevant source of support has been comparatively lacking. In this article, we present a multidimensional measure of community support (Perceived Community Support Questionnaire, PCSQ). Through exploratory and confirmatory factor analyses on data from three samples of adult population (two‐wave panel: sample 1, N = 1009 and sample 2, N = 780; and an independent sample 3, N = 440), results show that community integration, community participation, and use of community organizations are reliable indicators of the underlying construct of perceived community support. Also, community support is associated with a reduction of depressive symptoms after 6 months, once autoregression is controlled for. © 2007 Wiley Periodicals, Inc.
Inclusion of community in self scale: A single‐item pictorial measure of community connectedness
Authors: Mashek Debra , Cannaday Lisa W. , Tangney June P.
Published: February 2007

We developed a single‐item pictorial measure of community connectedness, building on the theoretical and methodological traditions of the selfexpansion model (Aron & Aron, 1986). The Inclusion of Community in the Self (ICS) Scale demonstrated excellent testñretest reliability, convergent validity, and discriminant validity in a sample of 190 college students. Importantly, results indicate that the ICS differentially assesses connectedness to the community, distinct from close relationship connectedness, suggesting that the ICS is both conceptually and empirically distinct from Aron, Aron & Smollan's (1992) Inclusion of Other in Self Scale. A secondary analysis of data from 297 incarcerated offenders offered favorable evidence for the generalizability of the measure. Together, results from two independent studies indicate that the ICS offers a simple, yet meaningful, measure of community connectedness. © 2007 Wiley Periodicals, Inc.
Fusarium species in sandy soil from Ipanema Beach, Rio de Janeiro, Brazil
Authors: de Moura Sarquis Maria Inez , de Moraes Borba Cintia
Published: February 2007

The presence of the genus Fusarium was investigated in sandy soil from Ipanema Beach, Rio de Janeiro, RJ, Brazil during a period of one year in order to determine the diversity, and seasonal distribution of species. A total of 123 strains were isolated, for a total of 34 different species, with higher incidence in spring and winter. The species detected in greater numbers during the various seasons of the year were, in decreasing order, F. solani var. solani, F. oxysporum var. oxysporum and F. sacchari var. subglutinans, described in the literature (GUARRO and GENÉ 1992) as infectious agents for humans and animals. Few species were detected in summer and fall, probably due to the higher rainfull occurring during these seasons.
Microbial populations associated with commercial bread production
Authors: Viljoen Clint R. , von Holy Alexander
Published: February 2007

The microbial ecology of a commercial bread production line was assessed by plate counts and characterization of microbial populations of raw materials, dough, equipment surfaces, air inside the bakery and baked bread. Aerobic plate counts for raw materials were higher than mould counts. Dough samples had high aerobic plate counts, but low mould counts. Mould counts on pre‐baking equipment surfaces were lower than those on post‐baking equipment surfaces, while aerobic plate counts on equipment surfaces varied. Counts of bacteria and moulds on bread increased during storage at 30 °C and moulds predominated over bacteria on air settle plates. Of the 316 bacterial isolates, 50% were Bacillus and 31.6% Micrococcus. Of the 97 mould isolates, 37.1% were Penicillium, 18.6% Aspergillus and 13.4% Cladosporium. Bacillus, Aspergillus and Penicillium were isolated predominantly from baked bread.
Comprehensive analysis of the climate variability in the eastern Mediterranean. Part II: relationships between atmospheric circulation patterns and surface climatic elements
Authors: Kostopoulou E. , Jones P. D.
Published: February 2007

In a companion paper, the authors presented a classification of circulation types for the eastern Mediterranean region. This paper has been directed towards the interrelationships between the identified atmospheric circulation patterns and the surface climate over the study region. On the basis of the characteristic days used to construct the composites of the dominant circulation modes, surface characteristics of five surface climatic elements (daily mean, maximum and minimum temperature, diurnal temperature range and daily precipitation totals) for these days were analysed. Subsequently, composite charts were produced illustrating the surface conditions accompanying the main circulation modes. The spatial patterns of temperature were found to be more coherent and depended less on the characteristics of local topography than those for precipitation. Winter patterns generally showed more pronounced structures. Atmospheric circulation associated with anticyclonic centres, leads to invasions of cold air into the study region and rather dry conditions across the region. Conversely, cyclonic circulation brings southern maritime airflows into the area and is associated with increases in local temperatures and rainfall events. During the warm season, generally warm and dry weather is associated with most of the circulation patterns and the surface patterns do not reveal very pronounced structures. Copyright © 2007 Royal Meteorological Society
Snow cover variability in Bulgarian mountainous regions, 1931–2000
Authors: Brown Ross D. , Petkova Nadezhda
Published: February 2007

Principal component (PC) analysis was carried out on annual snow cover series from 15 mountain climate stations in Bulgaria to characterize the spatial and temporal variability in snow cover over the 1931–2000 period. Three distinct snow cover response regions were identified: (1) high elevation sites above 1500 m in the Vitosha and Rila Mountains; (2) low elevation sites below 1000 m in the eastern Rhodope and southern Pirin Mountains and (3) a mid‐mountain zone of 1000–1500 m elevation including stations from several mountain ranges. Snow cover exhibited evidence of significant decadal‐scale variability over the 1931–2000 period but little evidence of long‐term trends linked to climate warming. Over the more recent 1971–2000 period, the mid‐mountain zone has increased in importance and shows a significant trend toward a later start to the snow cover season.

Composite analysis of high and low snow accumulation winters showed high accumulation years associated with a negative North Atlantic Oscillation (NAO)/East Atlantic (EA)‐like pattern that favored increased winter precipitation over the Mediterranean and Balkans and anomalous easterly flow across the Black Sea into Bulgaria. Low snow accumulation years were associated with the positive mode of a Scandinavian (SCA)‐like pattern that generated fall warming, a delay to the start of the snow cover season and reduced winter precipitation. Correlation of annual snow cover series with these modes of atmospheric variability revealed few significant correlations but evidence of considerable secular variability in the strength and sign of the relationships. This reflects the complex climate regime of Bulgaria, which is located at the cross‐roads of Mediterranean and Continental climate influences and on the periphery of the main nodes of influence of Northern Hemisphere circulation patterns that play important roles in European snow cover variability. Copyright © 2007 Royal Meteorological Society
Late Weichselian and holocene sea‐level history for a cross‐section of western Norway
Authors: Svendsen John Inge , Mangerud Jan
Published: February 2007

The postglacial sea‐level history along a cross‐section of western Norway has been studied in detail. Ten local sea‐level curves were used to construct an equidistant shoreline diagram, covering the last 13000 years. This includes 76 radiocarbon dates, of which the majority represent lacustrine sediments at the marine/lacustrine boundary in cores from emerged lakes. The distance between the westernmost and easternmost sites is 170 km and the difference in total emergence along this profile is more than 200 m. The shorelines all dip westward with a decreasing gradient through time. The Late Weichselian lines are all slightly curved whereas the Holocene lines are apparently straight. After the formation of the uppermost shoreline by around 12 800 BP there was a rapid emergence that decelerated with time to a near standstill during the Younger Dryas. From about 10 300 there was again a rapid emergence followed by the Tapes transgression along the coast and a standstill in the most easterly areas. At the western end of this profile, the Tapes transgression started around 9000 and culminated approximately 6000 BP, when a gradual regression occurred. To the east the early Holocene regression minimum occurs at a younger date and the transgression maximum is up to 1500 years older.
Nature and origin of ground ice, Sandhills Moraine, southwest Banks Island, Western Canadian Arctic
Authors: French H. M. , Harry D. G.
Published: February 2007

The Sandhills Moraine is a Late Wisconsinan lateral moraine complex on southwest Banks Island. The occurrence of ice‐ablation landforms, ground ice slumps, kettle lakes and catastrophic lake drainage in winter suggests the presence of substantial bodies of massive ground ice. The distinctive hummocky topography of the Sandhills Moraine is thought to reflect partial melt‐out of this ice. Stratigraphic observations indicate that the ice is overlain irregularly and unconformably by glacigenic sediments, notably pebbly clay (till) and/or sandy gravels (outwash), while the ice itself possesses numerous and variable mineral inclusions, faults and foliations. Petrofabric analyses indicate a strongly preferred orientation to the ice crystals. It is suggested that these characteristics are best explained if the ground ice is interpreted as relict glacier ice.
Late Quaternary volcanism in New Zealand: Towards an integrated record using distal airfall tephras in lakes and bogs
Authors: Lowe David J.
Published: February 2007

Studies on distal airfall tephra layers preserved in lake sediments and peats in northern New Zealand have documented the stratigraphic, chronologic, and compositional relationships of 46 eruptives, aged c. 17000–700yr BP, which originated from six North Island volcanic centres: Taupo (9 tephras), Okataina (8), Maroa (1) (rhyolitic); Mayor Island (2) (peralkaline); Tongariro (11), Egmont (15) (andesitic). Sources were distinguished by mineralogy and composition, field relations, and 14C chronology. All known rhyolitic tephra‐producing eruptions from Taupo, Okataina, and Maroa volcanoes since c. 17000yr BP are represented, but only a small proportion of the known tephras erupted from Tongariro, Egmont, or Mayor Island volcanoes is recorded. The distal tephras from these latter volcanic centres may thus reflect atypically powerful (or oblique) eruptions, or dispersal by strong winds. An improved record of volcanism for the Tongariro, Egmont, and Mayor Island centres might be obtainable from suitable lakes or bogs more proximal to them.
Holocene crustal movements and sea‐level changes in Great Britain
Authors: Shennan Ian
Published: February 2007

Crustal downwarping has occurred throughout southern and south‐eastern England and most of Wales for at least the last 4000 years, but the type of movement in some areas of southern and eastern England is more complicated than simple linear subsidence. Highest estimated rates of subsidence (since 4000 BP) are for the Thames Estuary and Norfolk (up to 2 mm/yr). Glacio‐isostatic processes have resulted in uplift in northern England and mainland Scotland. The rates of uplift have decreased throughout the Holocene; estimates for the present range from zero in south Lancashire and the Tees Estuary to over 1 mm/yr (though less than 2 mm/yr) in central Scotland.

Over 400 sea‐level index points, from the databank of 904 cases collected for IGCP Project 200, are grouped into 15 main areas and used to investigate the nature of crustal movements in Great Britain since 8800 BP, but there are significant deficiencies in available data which constrain the analysis.
The Loch Lomond Readvance on the Isle of Skye, Scotland: Glacier reconstruction and palaeoclimatic implications
Authors: Ballantyne Colin K.
Published: February 2007

Geomorphological mapping of southern Skye indicates evidence for a single readvance of locally‐nourished glaciers. These comprised a major icefield that occupied c. 155 km2of the main mountain area, a small icefield c. 10 km2in extent in the Kyleakin hills and ten corrie glaciers with a total area of c. 16 km2. The absence of Lateglacial pollen sites, shorelines and periglacial features within the limits of local glaciation implies a Loch Lomond Readvance age for this glacial event. The area‐weighted mean equilibrium line altitude (ELA) of the reconstructed Loch Lomond Readvance glaciers (319 m) conforms with a regional eastwards rise in ELAs that indicates dominant westerly airstreams during the Loch Lomond Stadial. An easterly decline in ELAs across the former icefields is interpreted in terms of easterly transfer of snow across ice‐sheds by westerly winds, though the altitudes of corrie glacier ELAs suggest that the dominant snow‐bearing winds were southerlies. Calculations based on the area‐weighted mean ELA for the major icefield (308 m) indicate a stadial mean July sea‐level temperature of c. 6 °C. The anomalously low gradients of certain former icefield outlet glaciers are attributed to deformation of subglacial sediment, an effect that may vitiate the assumption of linear ablation/accumulation gradients in the calculation of former ELAs for reconstructed glaciers.
Debris transport by Loch Lomond Readvance glaciers in Northern Scotland: Basin form and the within‐valley asymmetry of lateral moraines
Authors: Benn Douglas I. , Benn D. I.
Published: February 2007

Moraines in six cirques in Northern Scotland are shown to be asymmetrically developed, being larger below north‐ or east‐facing valley sides. Moraine asymmetry is strongly correlated with the distribution of free faces in the valleys, a relationship that is interpreted as the result of variation in slope retreat rates. Analysis of clast form and roundness demonstrates that following initial release from bedrock, debris entered both passive high‐level glacial transport and tractive transport at the ice‐bed interface. The importance of glacier velocities and medial moraines on debris flux is discussed. Consideration is also given to the implications of process asymmetry to long term landform development.
The history of Erica erigena R. Ross, an Irish plant with a disjunct European distribution
Authors: Foss Peter J. , Doyle Gerard J.
Published: February 2007

Scanning electron microscopy combined with pollen, spore, rhizopod and fungal analyses of two peat profiles at Claggan Mountain, Co. Mayo, sheds new light on the Holocene history of Erica erigena in western Ireland. This heather is referred to the Mediterranean‐Atlantic group in the Irish flora, and is remarkable for its disjunct distribution in Europe, where it occurs in Ireland, Bordeaux in France, and in Spain and Portugal.

Scanning electron microscopy has proved a powerful tool, allowing the unambiguous identification of ericoid pollens to species level and it is used to identify the first occurrence of Erica erigena pollen in the peat profiles. Radiocarbon dating of the profiles shows that Erica erigena is a relatively recent arrival at Claggan Mountain, appearing for the first time in the historic period at 1431 AD. The details of vegetational changes associated with the expansion of E. erigena have been explored by conventional pollen, spore, rhizopod and fungal analyses. Drying of the peat surface and replacement of bog vegetation by ericaceous heathland during a period of marked agricultural activity in the region was associated with its spread.

The relatively recent arrival of E. erigena at Claggan Mountain, suggests that introduction might explain its presence here, and its disjunct distribution in Europe. Documented trade and pilgrimage routes between Ireland and those areas in Europe where the heather occurs may have allowed its recent introduction into Ireland. Further pollen analysis work, using SEM techniques, will be required if an earlier occurrence for the heather in Ireland is to be proved. The combination of techniques described here may prove useful in the study of the history of other plants with pollen that is difficult to identify using conventional light microscopy.
European vegetation history: Palaeovegetation maps from pollen data ‐ 13 000 yr BP to present
Authors: Huntley Brian
Published: February 2007

Pollen data are the most important source of information with respect to late Quaternary vegetation history. Broad‐scale palaeovegetation patterns have been subjectively inferred from mapped pollen data by previous authors. In this study, multivariate classification was applied to European pollen data for the last 13 000 yr. The resulting clusters are mapped at millennial intervals and can be equated with vegetation units. The maps portray the changing vegetation of Europe since the last glacial. They reveal the impermanence of the assemblages of species that ecologists recognise as communities. The dominant patterns in the maps also change through time, indicating important changes in palaeoenvironmental conditions and in the alignment of major environmental gradients. Human impact upon European vegetation history is seen to be relatively unimportant when the vegetation is viewed at a continental scale.
Stratigraphy and thermoluminescence dating of Late Glacial cover sand in Denmark
Authors: Kolstrup Else , Grün Rainer , Mejdahl Vagn , Packman Susan C. , Wintle Ann G.
Published: February 2007

In western Jutland deposits with a texture and structure similar to Dutch cover sands have been found. Investigations have been carried out on the lithology and the lithostratigraphic sequences. Pollen analysis is used for biostratigraphic correlation, and ages have been obtained by the radiocarbon method as well as by thermoluminescence techniques using both quartz and eldspar. The five sites are presented separately and the data are integrated into a general stratigraphic outline of the Late Glacial cover‐sand sequence in Jutland.

During the latest part of the Upper Pleniglacial and the earliest Late Glacial, older cover‐sand type was deposited. Locally this sediment was also deposited during the later parts of the Late Glacial. Younger cover‐sand type was deposited primarily during the Early Dryas and Late Dryas, but some sand of this type was also laid down during the Allerød and the earliest Holocene. The palaeobotanical records are discontinuous, but plant growth was probably present throughout the Late Glacial; only during the Altered did the deposition of sand decrease long enough to allow a relatively stable vegetational development. The investigation shows that the sequence of events in Jutland is similar to the Dutch record.
Niveo‐aeolian sand deposition in subarctic dunes, eastern coast of Hudson Bay, Québec, Canada
Authors: Bélanger Simon , Filion Louise
Published: February 2007

Aeolian sand transport during winter and the snow‐free season was assessed quantitatively by direct year‐round field measurements along transects on the lee side of parabolic dunes in subarctic Québec. In 1987–1988, niveo‐aeolian deposition was more important than aeolian sedimentation in three of the four study sites, and contributed > 75% of the total annual accumulation in exposed sites and < 25% in protected forest sites. The maximum depth of interstratified snow and sand deposits (3.5 m) was recorded in March. Semi‐permanent snow lenses may persist longer than 2 years in the aeolian sediments. After dissipation of snow, 22 cm of sand (as a maximum) accumulated on the slipface of the most active dunes, whereas only minor sand accumulation occurred in distant areas from active sand erosion. Wind‐driven sand was dispersed over 7.4 km2 in the Whapmagoostui‐Kuujjuarapik area. The acumulation of snow and sand during the snow season, together with spring thaw and collapse of the niveo‐aeolian deposit, caused different types of injuries to trees, especially in 1985 and 1987 when a maximum of torn branches was recorded over the last 10 year period.
Glacial deposits at Wylfa Head, Anglesey, North Wales: Evidence for Late Devensian deposition in a non‐marine environment
Authors: Harris Charles
Published: February 2007

The nature and origin of glacial sediments at Wylfa Head are described, and their significance with regard to sedimentary environments during Late Devensian deglaciation of the Irish Sea Basin is discussed. Recent models of deglaciation under glaciomarine conditions are challenged. The Quaternary sequence at Wylfa consists of eroded and glaciotectonically deformed bedrock, locally derived lodgement till, calcareous silt‐rich lodgement till containing northern erratics, discontinuous units of orange‐brown silty sand of possible aeolian origin, and grey laminated freshwater silts filling a small kettle hole. The till units thicken to the south where the surface is drumlinised. It is concluded that the landforms and deposits result from a warm‐based Irish Sea glacier, which moved towards the southwest. Spatial variation in basal water pressure resulted from localised drainage through zones of more heavily jointed bedrock. Rapid glacial erosion occurred in areas where subglacial water pressure was relatively high, while deposition of the resulting basal sediment took place where water pressures were reduced. The glacier also carried basal calcareous silty till onshore, which was deposited by lodgement processes. None of the deposits at Wylfa are interpreted as glaciomarine in origin, and there is no evidence at this site for an isostatically induced marine transgression prior to deglaciation.
The Late Quaternary vegetational and climatic history of Easter Island
Authors: Flenley J. R. , King A. Sarah M. , Jackson Joan , Chew C. , Teller J. T. , Prentice M. E.
Published: February 2007

Easter Island occupies an exceptionally isolated position in the south Pacific Ocean. It is entirely volcanic, and is famous for its giant statues. Late Quaternary sediments have been investigated in three craters: Rano Raraku, Rano Aroi and Rano Kao, giving a continuous record over the past 30 Ka. Pollen records indicate that the island was formerly forested. Palynological and sedimentological evidence suggests a Late Pleistocene climate slightly cooler and drier than the present. Deforestation by people occurred mainly between 1200 and 800 yr BP. This may have led to an ecological disaster and to the decline of the megalithic civilization. The depauperation of the present native flora owes more to human activity than to isolation.