Paleoenvironmental reconstructions on a (supra-)regional scale have gained attention in Quaternary sciences during the last decades. In terrestrial realms, loess deposits and especially ...intercalations of loess and buried soils, so called loess-paleosol sequences (LPS) are important archives to unravel the terrestrial response to e.g. climatic fluctuations and reconstruct paleoenvironments during the Pleistocene. The analysis of LPS requires the knowledge of several key factors, such as the distribution of the aeolian sediments, their location relative to (potential) source areas, the climate conditions that led to their emplacement and the topography of the sink area. These factors strongly influence the sedimentological and paleoenvironmental characteristics of LPS and show broad variations throughout Europe, leading to a distinct distribution pattern throughout the continent.
We present a new map of the distribution of aeolian sediments (mainly loess) and major potential source areas for Europe. The map was compiled combining geodata of different mapping approaches. Most of the used geodata stems from accurate national maps of 27 different countries. Problematic aspects such as different nomenclatures across administrative borders were carefully investigated and revised. The result is a seamless map, which comprises pedological, geological, and geomorphological data and can be used for paleoenvironmental and archeological studies and other applications.
We use the resulting map and data from key geomorphological cross-sections to discuss the various influences of geomorphology and paleoenvironment on the deposition and preservation of Late Pleistocene loess throughout Europe. We divided the loess areas into 6 main loess domains and 17 subdomains to understand and explain the factors controlling their distribution and characteristics. For the subdivision we used the following criteria: (1) influence of silt production areas, (2) affiliation to subcatchments, as rivers are very important regional silt transport agents, (3) occurrence of past periglacial activity with characteristic overprinting of the deposits. Additionally, the sediment distribution is combined with elevation data, to investigate the loess distribution statistically as well as visually.
Throughout Europe, the variations, and differences of the loess domains are the results of a complex interplay of changing paleoenvironmental conditions and related geomorphologic processes, controlling dust sources, transport, accumulation, preservation, pedogenesis, alongside erosional and reworking events. Climatic, paleoclimatic, and pedoclimatic gradients are on the continental scale an additional important factor, since there are e.g. latitudinal differences of permafrost and periglacial processes, an increase in continentality from west to east and in aridity from northwest to southeast and south, strongly affecting regional sedimentary and geomorphic dynamics.
We propose three main depositional regimes for loess formation in Europe: (1.) periglacial and tundra loess formation with periglacial processes and permafrost in the high latitude and mountainous regions; (2.) steppe and desert margin loess formation in the (semi-)arid regions; and (3.) loess and soil formation in temperate and subtropical regions. Loess deposits of (1.) and (2.) show coarser, sandier particle distributions towards the glacial and desert regions. In the humid areas (3.) forest vegetation limited dust production and accumulation, therefore, there is an increase in finer grain sizes due to an increase in weathering.
•New seamless loess map of Europe including related Late Pleistocene sediments•Review on European loess landscapes divided in six domains and 17 subdomains•Geomorphology of loess regions including 3D images of selected loess landscapes•New conceptual model of loess genesis in Europe•Paleoenvironmental variations determine spatial pattern of loess formation and domain subdivision
Recent advances in post-IR IRSL dating have led to breakthroughs in dating upper Middle Pleistocene loess sequences. Here, an elevated temperature post-IR IR protocol using a second IR stimulation ...temperature of 290°C is applied to eleven polymineral fine-grain (4–11μm) samples from the lower part of the Middle–Lower Pleistocene Stari Slankamen loess–palaeosol sequence with the aim of refining the site's age model and investigating the behaviour of both the IR50 and the pIRIR290 signals in material close to or in luminescence signal saturation. Both signals from the 8 samples below the prominent erosion surface represented by a gravel layer at ~13m were found to be in field saturation (i.e. no systematic increase in burial dose with depth). The average ratio of the sensitivity-corrected natural signal to the laboratory saturation level for the pIRIR290 is 1.00±0.03 (n=8) indicating that field saturation is equal to laboratory saturation for this signal. Minimum equivalent dose estimates were calculated from 2*D0 values, giving minimum age estimates of ~230–390ka; this result suggests an upper limit for dating these loess deposits of ~300ka. The age estimate of the younger sample SSK2 is in good agreement with the quartz OSL age, showing that the pIRIR290 signal is bleachable in nature and can be used to date material as young as ~20ka. Our data suggest that the loess unit V-L2 accumulated during Marine Isotope Stage (MIS) 6 and that the erosional event marked by an unconformity and gravel layer between loess units V-L2 and V-L3 has a minimum age of ~170ka. Pedocomplex V-S1 can be correlated with the complete MIS 5 period. Furthermore we suggest a minimum age of ~250ka for the loess unit V-L3 and palaeosols V-S3, V-S4 and V-S5; considerably older than proposed by many previous studies.
•Luminescence dating of Stari Slankamen loess gives ages from 20 ka to >250ka.•Youngest feldspar age supported by quartz age.•Both IR50 and pIRIR290 signals in field saturation in older samples.•PIRIR290 signals from older samples also in laboratory saturation — no fading.
Recent investigations of the Semlac loess section in the south-eastern Carpathian Basin, which is situated at an undercut slope position on the right bank of the Mureş River in its lower reaches ...(Banat region, western Romanian), are presented and discussed. Dating back to marine isotope stage (MIS) 10, the more than 10 m thick loess sequence includes four fossil soil-complexes developed in homogenous and relatively fine silty loess. Because of the good preservation of the sediment, Semlac is regarded as a key section for the Carpathian Basin, which offers possibilities to a) improve the understanding of the type and composition (loess homogeneity and pedogenic alteration) of the lowland loess sequences in the Carpathian Basin also beyond the last interglacial palaoesol complex, b) to reconstruct the temporal evolution of the local loess-palaoesol successions, c) gain better insight into the regional paleoenvironments of the last 300 ka and d) to compare the loess of the region to loess-sequences in adjacent areas and to dust proxy data in the northern hemisphere.
An integrated age model based on correlation to reference records and luminescence dating is compiled. Applying this age model we compare climate proxy data from Semlac to both global data and to data from the very southeast of the Carpathian Basin (Vojvodina, Serbia).
The obtained results provide new insight into the dust accumulation regime for the eastern Carpathian Basin and offer new palaeoenvironmental information for the region and are an important step towards establishing a catena from the thin loess-like sediments of the Banat foothills in the East towards the thicker and seemingly more complete loess sections of the south-eastern and central Carpathian Basin. Disentangling grain size data from soil formation proxies is used to investigate patterns of non-local dust. Patterns of non-pedogenetic fine material are similar to grain size proxies from China and other parts of the northern hemisphere, suggesting western and eastern Eurasian loess to have (at least partly) similar mechanistic/climatic origins.
•We present physical property data from the eastern Carpathian Basin for the last ca. 400 thousand years.•Temporal physical property patterns are smooth and different from sections near the Danube.•We discuss similarity of a model for dust accumulation regime with data to global dust deposition.
This is a contribution to the reconstruction of the eolian transport processes and wind directions in south-eastern Europe during the Weichselian Pleniglacial. The study is based on eight loess ...sections: three west and five east of the Carpathian Mountains. The loess dispersal patterns in the area is interpreted by the loess grain-size distribution and mass accumulation rates (MARs) in relation to the topography. The grain-size dataset is subdivided in four endmembers (EMs) by means of the endmember modelling algorithm EMMA. The temporal evolution of the individual EMs is based on a number of absolute datings (25 IRSL and one
14C). The MARs and proportions are calculated per unit of the Pleniglacial (Early, Middle and Late). Both the MAR-results and the EM proportions suggest a prevailing western wind during the Early and Middle Pleniglacial and a dominant northwestern wind during the Late Pleniglacial.
Using the microwave-hydrothermal method for the synthesis of composite, high surface density of hydroxyl groups, as an active adsorption sites for arsenic, was obtained. Adsorption mechanisms of ...As(III) and As(V) onto zirconium-doped titanium dioxide (Zr-TiO
2
) were investigated and proposed using macroscopic and microscopic methods. Obtained results are suggesting inner-sphere and outer-sphere adsorption mechanisms for As(III) and As(V), respectively. This allowed us to identify parameters that are critical for the successful removal of arsenic from water, which is essential information for further optimization of the removal process. The composite was further applied for the removal of As(III) and As(V) from water in a dynamic flow through the reactor. Column study proved that the removal of both arsenic species below the value recommended by WHO can be achieved. Elution of As(III) and As(V) from the composite can be done by using small amounts of 0.01 M NaOH solution resulting in preconcentration of arsenic species and possible multiple usage of composite.
Despite the general satisfactory performance of quartz in the single aliquot regeneration protocol (SAR), previous optically stimulated luminescence (OSL) dating studies of key loess sections in ...Romania, Lower Danube region, revealed a disturbing disagreement among the ages obtained on fine (4–11 μm) grains and coarse (63–90 μm) grains respectively. The current study aims at expanding these investigations, both by extending the area of study from the Lower Danube Basin to the Carpathian Basin and by applying time-resolved optically stimulated luminescence (TR-OSL) on quartz, in order to gain further insights into the above mentioned behaviour. The samples from the Orlovat loess paleosol section (Vojvodina, Serbia) showed a similar behaviour to that previously reported on Romanian loess. A marked difference between the dose saturation characteristics of fine and coarse quartz OSL signals is observed for both continuous wave (CW-OSL) and pulsed OSL (POSL), where the dose response (up to 1000 Gy) is well described by a sum of two saturating exponential functions. TR-OSL measurements show one single, characteristic quartz lifetime for both natural as well as regenerative signals in the entire dose range investigated. A general disagreement between the ages obtained on the two grain sizes for samples with equivalent doses higher than about 100 Gy is reported as in the case of Romanian loess, inferring that the age discrepancy between the two grain sizes might be more widespread than previously thought.
Loess deposits intercalated by paleosols are detailed terrestrial archives of Quaternary climate variability providing information on the global dust cycle and landscape dynamics. Their paleoclimatic ...significance is often explored by quantifying their mineral magnetic properties due to their sensitivity to local/regional hydroclimate variability. Detailed chronological assessment of such regional proxy records around the climatic transitions allow a better understanding of how regional records react to major global climatic transitions such as the Pleistocene-Holocene climatic transition.
Logs of high-resolution magnetic susceptibility and its frequency dependence were used as paleoclimatic proxies to define the environmental transition from the last glacial loess to the current interglacial soil as reflected in nine loess-paleosol sequences across the northern hemisphere, from the Chinese Loess Plateau, the southeastern European loess belt and the central Great Plains, USA. The onset of increase in magnetic susceptibility above typical loess values was used to assess the onset of, and developments during, the Pleistocene-Holocene climatic transition.
High-resolution luminescence dating was applied on multiple grain-sizes (4–11 μm, 63–90 μm, 90–125 μm) of quartz extracts from the same sample in order to investigate the timing of Pleistocene-Holocene climatic transition in the investigated sites.
The magnetic susceptibility signal shows a smooth and gradual increase for the majority of the sites from the typical low loess values to the interglacial ones. The initiation of this increase, interpreted as recording the initiation of the Pleistocene-Holocene climatic transition at each site, was dated to 14–17.5 ka or even earlier. Our chronological results highlight the need of combining paleoclimatic proxies (magnetic susceptibility) with absolute dating when investigating the Pleistocene-Holocene climatic transition as reflected by the evolution of this proxy in order to avoid chronostratigraphic misinterpretations in loess-paleosol records caused by simple pattern correlation.
The detailed luminescence chronologies evidence the continuity of eolian mineral dust accumulation regardless of glacial or interglacial global climatic regimes. Coupled with magnetic susceptibility records this indicates that dust sedimentation and pedogenesis act simultaneously and result in a non-negligible accretional component in the formation of Holocene soils in loess regions across the Northern Hemisphere. The luminescence ages allowed the modeling of accumulation rates for the Holocene soil which are similar for European, Chinese and U.S.A. loess sites investigated and vary from 2 cm ka−1 to 9 cm ka−1. While accretional pedogenesis has often been implicitly or explicitly assumed in paleoclimatic interpretation of loess-paleosol sequences, especially in the Chinese Loess Plateau, our luminescence data add direct evidence for ongoing sedimentation as interglacial soils formed.
•High-resolution magnetic susceptibility record as paleoclimate proxy.•High-resolution luminescence dating applied on multiple quartz fractions.•Initiation of magnetic susceptibility enhancement dated prior to ~11.7 ka.•Continuous dust accumulation during Pleistocene-Holocene transition and in Holocene.•Accretional Holocene soils in European, Chinese Loess Plateau and US loess sites.
To examine potential relationships between meteorological variables and forest fires in Serbia, daily temperature, precipitation, relative humidity and wind speed data for 15 meteorological stations ...across Serbia were used to construct fire indices. The daily values of the Ångström and Nesterov indices were calculated for the period 2000–2017. A high number of forest fires occurred in 2007 and 2012 in Serbia, during a period of extremely high air temperatures in 2007, followed by the longest heat wave and the worst drought in 2012.
In order to identify the ideal weather conditions for fire break outs, different combinations of input variables, e.g., meteorological variables (mean temperature, precipitation, relative humidity, maximum temperature, minimum temperature and wind speed), fire danger indices or a combination of both, for the Belgrade area during the period 1986–2017, were tested. It was found that using relative humidity or precipitation as a predictor only generates a satisfactory model for forecasting of number of forest fires.
The San Joaquin Valley (SJV) experiences some of the worst ozone air quality in the US, frequently exceeding the California 8 h standard of 70.4 ppb. To improve our understanding of trends in the ...number of ozone violations in the SJV, we analyze observed relationships between organic reactivity, nitrogen oxides (NOx), and daily maximum temperature in the southern SJV using measurements made as part of California at the Nexus of Air Quality and Climate Change in 2010 (CalNex-SJV). We find the daytime speciated organic reactivity with respect to OH during CalNex-SJV has a temperature-independent portion with molecules typically associated with motor vehicles being the major component. At high temperatures, characteristic of days with high ozone, the largest portion of the total organic reactivity increases exponentially with temperature and is dominated by small, oxygenated organics and molecules that are unidentified. We use this simple temperature classification to consider changes in organic emissions over the last and next decade. With the CalNex-SJV observations as constraints, we examine the sensitivity of ozone production (PO3) to future NOx and organic reactivity controls. We find that PO3 is NOx-limited at all temperatures on weekends and on weekdays when daily maximum temperatures are greater than 29 °C. As a consequence, NOx reductions are the most effective control option for reducing the frequency of future ozone violations in the southern SJV.
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