lateglacial climate development in nw romania comparative results from three quantitative pollen based methods abstract this paper provides quantitative reconstructions of the lateglacial changes in four climate parameters from two fine resolution pollen profiles in the gutaiului mountains nw romania climate estimates are based on two modern analogue techniques with and without considering vegetation types and weighted averaging partial least squares regression wa pls giving evidence for several climatic fluctuations during the period from 14 700 to 11 500 cal yr bp the comparative results of the two modern analogue techniques show consistent trends of climate changes that are also coherent at both sites but these results appear to largely disagree compared with climate reconstruction provided by wa pls the modern analogue techniques revealed four intervals with low temperatures prior to 14 700 cal yr bp between 13 950 and 13 800 13 400 and 13 200 and 12 700 and 11 700 cal yr bp the temperature declines were more pronounced for winter than for summer suggesting an intensification of seasonality which together with a drop in precipitation indicates an increase in continentality the younger dryas is the most pronounced cooling phase with winter temperatures 14 16 c colder than modern conditions annual and summer temperatures 2 5 c and 2 c respectively below present ones precipitation was 400 500 mm half that of present during the bolling and allerod summer temperatures were close to modern values 13 to 17 c whereas winter 6 to 12 c and annual temperatures 0 5 to 6 c as well as precipitation were 550 to 700 mm lower indicating more continental conditions compared to the present day climate

last 1000 years of environmental history in southern bucovina romania a high resolution multi proxy lacustrine archive geo ecological and landscape change studies at a local scale are scarce in central eastern europe and particularly in romania however this focus is directly relevant to ecosystems and humans as both are dependent on local environmental changes we perform a high resolution multi proxy analysis of physical and geochemical sediment properties coupled to plant macrofossil pollen and charcoal analysis at iezerul sadovei lake and present the first palaeoenvironmental reconstruction from bucovina mountains the north eastern romania the sedimentary record spanning the last 950 years is laminated throughout and reveals high intensity catchment responses to changes in hydrological conditions and human impact results show major landscape disturbances 950 years ago and during the last 200 years the enhanced catchment instability from the onset of sedimentation to 1400 ce was characterised by landsliding and subsequent erosion and related mainly to natural factors however the most recent since c 1800 ce environmental changes i e deforestation enhanced channel and slope erosion and lake in filling are a consequence of direct human interventions changes in the composition and extent of forest cover were also driven by the combination of natural disturbances climate variability and anthropogenic activities from 1400 ce and more clearly over the last 200 years early successional and disturbed habitat taxa appeared to respond primarily to anthropogenic drivers including forest management the higher proportion of abies alba 30 and fagus sylvatica 20 in the local forest and their dramatic decline was recorded earlier i e 1150 ce and 1400 ce respectively than reported in other parts of the romanian carpathians using this palaeoenvironmental evidence as an analogue projected climate changes i e increased seasonal heavy precipitation and more frequent extreme events superimposed on increasing human pressure are likely to lead to the destabilisation of the catchment through erosion and possible reactivation of landslides

temperature inversions thermal tides and water ice clouds in the martian tropics 1 we report new results on the structure and dynamics of the tropical atmosphere of mars derived from a combination of radio occultation measurements by mars global surveyor and simulations by a mars general circulation model mgcm radio occultation experiments sounded the equatorial atmosphere at latitudes of 36 n to 30 s during midsummer of the northern hemisphere ls 134 162 sampling the predawn thermal structure at a local time of 0412 elevated temperature inversions are a conspicuous feature of these observations they appear at pressures between 30 and 200 pa well above the surface and their magnitude exceeds 6 k in 34 of the temperature profiles in this latitude band the properties and spatial distribution of these elevated inversions are organized across the tropics on planetary scales inversions are strongest and occur most frequently above elevated terrain achieving a peak magnitude of 30 k near tharsis and their altitude generally increases toward the south according to mgcm simulations which closely resemble the observations these temperature inversions arise from zonally modulated thermal tides the best simulation includes an interactive hydrologic cycle which results in strong coupling between the thermal tides and radiatively active water ice clouds prominent clouds form in response to wave induced adiabatic cooling and evolve in a pattern closely correlated with the thermal structure of the tides the tides in turn are intensified by radiative forcing from the clouds this tide cloud coupling imposes strong diurnal modulation on the properties of clouds in the tropics

late holocene history of the moldova river valley romania abstract this paper describes the results of geomorphological sedimentological and 14 c analyses of late holocene fluvial sequences in the moldova river valley of romania this river originates from the carpathians mountains and is known for the extent of its large floodplain and sediment thickness between the molid and timisesti localities river length 86 km numerous large fossil trunks of oak poplar and beech trees are exposed in the riverbanks six wood samples were selected for radiocarbon absolute dating conventional method and their ages ranged from 410 to 3200 cal yrs bp the thickness of the alluvial sediments above the sampled fossil trunks varied between 2 and 3 m and these sediments predominantly consisted of coarse gravel materials that had similar granulometry to sediments that were present in the modern riverbed additionally in the same investigated areas successive floodplain cross sections were constructed based on more than 20 hydrogeological boreholes for each cross section all data were used to calculate the local values of bed loads and these values were compared to the absolute ages of the fossil trunks and were in the range of 300 m 3 m and 5500 m 3 m based on the calculated values during the last 780 years the floodplain sedimentation rates were estimated to be in the range of 0 4 m 3 year at the molid section which was located in the mountainous area of the valley and 44 km downstream from the river headwater and during the last 410 years the sedimentation rate at the praxia section which was located 125 km downstream from the river headwater was 13 3 m 3 year in the past 100 years the fluvial processes along the moldova river were dominated by a narrowing by an average of 76 and an incision up to 2 5 m and a channel metamorphosis from braided to wandering was reported these results are discussed in the context of late holocene regional and local palaeoclimatic reconstructions as well as that of human interventions

a chironomid based reconstruction of late glacial summer temperatures in the southern carpathians romania late glacial and early holocene summer temperatures were reconstructed based on fossil chironomid assemblages at lake brazi retezat mountains with a joint norwegian swiss transfer function providing an important addition to the late glacial quantitative climate reconstructions from europe the pattern of the late glacial temperature changes in lake brazi show both similarities and some differences from the ngrip 18o record and other european chironomid based reconstructions our reconstruction indicates that at lake brazi 1740 m a s l summer air temperature increased by 2 8 c at the oldest dryas bolling transition gs 2 gi 1 and reached 8 1 8 7 c during the late glacial interstade the onset of the younger dryas gs 1 was characterized by a weak 1 c decrease in chironomid inferred temperatures similarly at the gs 1 holocene transition no major changes in summer temperature were recorded in the early holocene summer temperature increased in two steps and reached 12 0 13 3 c during the preboreal two short term cold events were detected during the early holocene between 11 480 11 390 and 10 350 10 190 cal yr bp the first cooling coincides with the preboreal oscillation and shows a weak 0 7 c temperature decrease while the second is characterized by 1 c cooling both cold events coincide with cooling events in the greenland ice core records and other european temperature reconstructions

high mountain region of the northern romanian carpathians responded sensitively to holocene climate and land use changes a multi proxy analysis a high altitude lake sediment sequence buh iescu mare 1918 m a s l in the subalpine zone of the rodna mountains was analysed through a multi proxy approach to determine the sensitivity of high mountain habitats to climate fire and land use changes the early holocene regional forests were dominated by pinus sylvestris and mugo and replaced by picea abies from 9800 cal yr bp after an extended hiatus in the profile c 9800 4200 cal yr bp probably because of the physical removal of sediments through avalanche or high flow events p abies abies alba and fagus sylvatica forests developed after 4200 cal yr bp the timberline and treeline reacted sensitively to past changes in climate and human impact the site was probably situated above the treeline throughout most of the investigated period however a treeline ecotone or krummholz zone may have sporadically reached the lake s elevation in the early holocene a decline in timberline and treeline elevation was noted during the last 1200 years and more evidently over the past 200 years with replacement by subalpine shrubs alnus viridis and alpine herbaceous communities because these vegetation changes were associated with an increased prevalence of pollen based anthropogenic indicators charcoal particles and abiotic indicators human induced fires and clearance and resultant erosion inputs to the lake are implied effects of current warming on the altitude range of trees are not yet visible probably because land use has more strongly contributed to changes in land cover than the climate fluctuations of the last millennium in the rodna mountains

the use of mineral magnetism in the reconstruction of fire history a case study from lago di origlio swiss alps abstract the use of magnetic measurements in the detection of fire signals has been neglected since the work of rummery et al 1979 yet considerable developments have been made in the interpretation of magnetic measurements over the last 16 years this paper presents a study of the fire history of lago di origlio in the southern swiss alps the study utilises the technique of mineral magnetism alongside the stratigraphic pollen spore and charcoal records correlation between the various proxy records indicates that a magnetic fire record is present within the sediments for the last 4 ka the magnetic fire record has a distinct mineralogical and magnetic grain size signature that can be recognised against the background sedimentary signal the results suggest that magnetic measurements may be usefully employed in the reconstruction of fire history their application is rapid and non destructive and the results may provide additional information in relation to the links between catchment fire events and the sedimentary record

holocene vegetation history in the upper forest belt of the eastern romanian carpathians abstract pollen analysis supported by nine ams 14 c dates from the poiana tiol peat sequence 1540 m in the rodnei mountains eastern romanian carpathians romania is used to reconstruct the holocene vegetation history in this mountain region the results are then compared with other sequences from romania and eastern europe in order to better understand the past dynamics of the main forest constituents the vegetation record at poiana tiol starts at ca 11 000 cal yr bp with the occurrence of rather closed woodlands composed of betula pinus picea abies alnus a viridis and ulmus picea abies was the dominant tree species for almost the entire period however during the last 3000 years p abies forests were largely replaced by pinus in the area temperate tree taxa fraxinus quercus acer tilia and corylus avellana were also common but likely at lower elevation c avellana expanded around 10 300 cal yr bp and reached maximum values after 9000 cal yr bp pollen of carpinus betulus and fagus sylvatica was already recorded around 7000 cal yr bp however the spread of c betulus occurred at ca 6000 cal yr bp with maximum values between 4800 cal yr bp and 3000 cal yr bp while f sylvatica spread from ca 3200 cal yr bp and attained maximum values between 2000 and 200 cal yr bp the first indications of human activities appeared around 3200 cal yr bp and intensified within the last 200 years comparison with other sequences from romania and surrounding countries reveals both similarity and great differences related to the location of glacial refugia climate change and human impact

carbon isotope composition as indicator for climatic changes during the middle and late holocene in a peat bog from maramures mountains romania the main goal of this study was to use stable carbon isotopic composition of bulk peat sampled in t ul mare bard u peat bog maramures mountains as a tool to provide paleoclimatic information over the middle and late holocene in this region a peat core of 3 60 m was sampled for 13c analysis and bulk peat samples were analyzed by isotope ratio mass spectrometry irms method 13c values reveal a maximum variation of 4 69 along a 3 6 m long peat core we examined the vertical variation of 13c bulk peat and concluded that several factors could contribute to up core trends of 13c four intervals of climatic variability could be related with variations of 13c values between 6800 cal yr bp and present two wet periods around 2800 and 545 cal yr bp and two dry periods 6760 and 1430 cal yr bp we concluded that variability in the 13c of bulk peat profile could be influenced most heavily by the water availability which in turn is related to the amount of precipitation at the time four intervals

circum mediterranean fire activity and climate changes during the mid holocene environmental transition 8500 2500 cal bp a mid to late holocene synthesis of fire activity from the mediterranean basin explores the linkages among fire climate variability and seasonality through several climatic and ecological transitions regional fire histories were created from 36 radiocarbon dated sedimentary charcoal records available from the global charcoal database during the mid holocene thermal maximum around 7500 4500 cal bp charcoal records from the northern mediterranean suggest an increase in fire while records from the southern mediterranean indicate a decrease associated with wetter than present summers a north south partition between 40 and 43 n latitude is apparent in the central and western mediterranean relatively abrupt changes in fire activity are observed c 5500 5000 cal bp records of holocene fire activity appear sensitive to both orbitally forced climate changes and shorter lived excursions which may be related to north atlantic cold events possibly modulated by an nao like climate mechanism in cases wh

the role of fire in landscape dynamics an example of two sediment records from the rodna mountains northern romanian carpathians fire is an important disturbance agent worldwide and one of the major causes of geomorphological change dependent on its characteristics size duration temperature fire induces changes in soil stability modifying infiltration and promoting soil erosion here we employ a suite of physical mineral magnetic loss on ignition geochemical xrf derived elemental data biological macro charcoal pollen proxies and dating measurements ams 14c 210pb and 137cs to examine the relationship between fire activity sedimentary characteristics and geomorphological change over the holocene our results highlight that fire events imprint a magnetic signature characterised by secondary ferrimagnetic assemblage particularly very fine superparamagnetic sp magnetite and maghemite in lake buh iescumare the early holocene is characterised bymoderate fire activity and coarser sediment particle size indicating a relatively unstable catchment affected by burning events which activated erosional processes subsequently the late holocene 4 000 0 cal yr bp is marked by intermittently variable fire activity with sporadic increases between 3 400 and 3 200 cal yr bp and around 2 000 cal yr bp when burning was strong enough to lead to the magnetic enrichment of topsoil and detrital inputs to the lake in our high resolution record lake tiol the interval 2 500 700 cal yr bp and also the last 100 years are characterised by intense burning that coincides with sustained surface soil erosion and magnetic enrichment the fire erosion landscape relationship varies over time being highly dependent on fire behaviour fire temporal and spatial distribution and landscape features slope soil type vegetation cover

establishing fire incidence in temperate soils using magnetic measurements abstract natural unburnt topsoil samples from the cotswolds region of england and samples from archaeological contexts in the uk and hungary some of which are known to have been affected by burning have been used to identify a distinctive magnetic signature linked to the effects of fire on magnetic properties a combination of bulk low field lf and frequency dependent fd magnetic susceptibility and normalized anhysteretic remanent magnetization arm measurements have been used on both unburnt and experimentally burnt samples from the cotswolds and on the archaeological samples complementary determinations were made for both sets of samples of the maximum potential susceptibility max and hence percentage fractional conversion conv which provides independent evidence of burning the results show that the ferrimagnetic mineral assemblages produced as a result of fire have a significantly finer grain size than those arising from weathering and soil formation alone burning thus gives rise to a distinctive envelope of values on a bilogarithmic plot of arm fd versus arm lf such a diagram provides a convenient basis for identifying magnetic signatures in soils archaeological materials and palaeosols that have arisen mainly through burning

sources of fine grained magnetic minerals in sediments a problem revisited progress in the discrimination of fine grained magnetic minerals in sediments and sediment sources using measurements of magnetic susceptibility at two frequencies and of magnetic remanence generated by a combination of direct and alternating currents is summarized the former measurements yield values for low field and frequency dependent susceptibility lf and fd respectively the latter generate an anhysteretic remanent magnetisation arm that when normalized to the dc bias field can be represented as the susceptibility of arm arm using quotients derived from lf fd and arm to generate bi logarithmic plots it is possible to discriminate between assemblages dominated by magnetic minerals formed through pedogenesis and those arising from the presence of magnetotactic bacteria that use chains of magnetic particles to seek optimum environments in surface sediments sediments to which both types of magnetic mineral contribute occupy positions between the envelopes of values typical of soil d

the effects of wildfires on the magnetic properties of soils in the everglades we present results of a rock magnetic study of soils that were affected by wildfires that burned portions of the everglades in the spring of 2008 soils at sites that were extensively burned exhibit a pronounced surface magnetic enhancement effect with magnetizations of surface samples up to 16 times greater than that observed at depth 7 cm at these sites the increase in magnetization results from an increased abundance of a low coercivity phase maghemite that occurs at the expense of the abundance of a high coercivity phase goethite these results indicate that fire induced heating caused goethite in the surface soils to convert into a more magnetic low coercivity phase such as maghemite goethite is an excellent adsorber of phosphorus and therefore we hypothesize that the destruction of goethite as a result of burning may have important implications for phosphorus cycling in the everglades ecosystem copyright 2010 john wiley sons ltd

long term summer temperature reconstruction inferred from tree ring records from the eastern carpathians the first 1 000 year long carpathian tree ring width chronology was established based on living and subfossil stone pine pinus cembra l samples from an upper timberline forest located in calimani mts romania tree ring data were standardized using the regional curve standardization method in order to preserve the low and medium frequency climate signals the de trended index strongly correlates with summer mean temperature both at annual and decadal scales the calimani summer mean temperature anomalies were reconstructed for the period ad 1163 2005 applying the rescaling method this new climate proxy from the carpathians shows similar fluctuations to other north hemispheric temperature reconstructions but with periods of distinct differences the fingerprint of little ice age in the calimani area is visible between ad 1370 and 1630 followed by lagged cold decades in ad 1820 and 1840 the recent warming is evident only after the 1980s in our reconstruction

a late glacial paleolake record from an up dammed river valley in northern transylvania romania lake sediments from the magherus valley in the lowlands of northern transylvania provide new evidence of paleoenvironmental development in romania during the late glacial the studied sediments were deposited as a result of the damming of a small river valley following a series of mass wasting events that occurred during the deglaciation period a continuous sedimentary sequence belonging to the former lake is preserved in the banks of the stream and contains evidence of paleoenvironmental changes associated with the late glacial interstadial bolling allerod or greenland interstadial 1 gi 1 and the late glacial stadial younger dryas or greenland stadial 1 gs 1 implying that the hallmark climatic episodes of northwestern europe are also expressed in eastern europe we employ a multiproxy approach based on the analysis of sediment composition and texture mineral magnetism organic macrofossils and radiocarbon dating the reconstructed paleoenvironmental evolution at the site captures the warm and humid conditions associated with gi 1 as well as the subsequent cooling concomitant with the onset of gs 1 these climatic events are paralleled by vegetation shifts in the region as deduced from comparisons with pollen sequences from magherus and neighboring locations in transylvania and the carpathians the late glacial interstadial was warmer and wetter as evidenced by increased organic matter content in the lake decreased erosion in the catchment development of palustrine plant communities in the proximity of the lake and expansion of spruce during the allerod gi 1c a the late glacial stadial was colder and dryer as indicated by low sedimentary organic matter content an increase in erosion markers and the decline of spruce and its replacement by birch the landscape was more open as herbs and grasses also expanded during this time these fluctuations imply that late glacial climatic events are well expressed not only in upland areas of romania but also in lowland regions such as the transylvanian basin where climatic effects are expected to be more muted c 2014 elsevier ltd and inqua all rights reserved

magnetism of al substituted magnetite reduced from al hematite this study was supported by national program on global change and air sea interaction gasi 04 01 02 the national natural science foundation of china grants 41504055 41430962 41374073 and 41025013 and chinese continental shelf deep drilling program gzh201100202 z x j further acknowledges support from the china postdoctoral science foundation a p r and d h acknowledge support from the australian research council grants dp110105419 and dp120103952

soil properties and charcoal dynamics of burnt soils in the tyrolean limestone alps abstract we investigated soil samples of four burnt slopes in the tyrolean limestone alps of varying age after fire wildfires occurred in 2003 1962 1946 and in 1250 ad as well as of the surrounding soils that were not affected by combustion charcoal content of the o and a horizons was determined as well as ph soil organic matter content and c n ratio the results showed a background value of charcoal in all soils with a dominance of charcoal in the o horizon of the youngest burnt slope 2003 with vegetation and soil recovery charcoal concentrations decreased and zones of maximum charcoal accumulation shifted further down in the soil profile soil organic matter contents significantly decreased on burnt slopes which is due to vegetation combustion long term vegetation changes and intensified erosion however in the long term re accumulation occurs due to the recovery of vegetation soil ph increased by combustion and was further modified by an altered vegetation composition c n ratios remained largely stable with the soil n content reacting more sensitive to combustion the results demonstrate that alpine regions react sensitively to wildfires due to the steep slope angle which causes not only short term but also long term modification in vegetation composition and erosion

lake sediment records of atmospheric pollution in the romanian carpathians abstract short lake sediment cores from ten lakes in the romanian carpathians have been characterised both mineral magnetically and geochemically providing an assessment of the potential of these mountain lakes sediment records as a retrospective indicator of atmospheric pollution mineral magnetic characteristics suggests that recent sediments have been affected by atmospheric particulate pollution associated with fossil fuel combustion and vehicle emissions although the properties may also reflect within lake processes metal enrichment factors for contemporary sediments reveal that remote mountain lakes in this region appear to have been impacted by the long range atmospheric transport of metallic pollutants the results suggest that sites in the southern mountains are most impacted although trace metal levels are relatively modest initial findings suggest that some sites have the potential to provide lake sediment based pollution histories that will thereby contribute to a fuller europe wide understanding of the impact of atmospheric pollutants in upland regions

the subsurface structure and stratigraphic architecture of rift related units in the lishu depression of the songliao basin china abstract this contribution reports the basin configuration feature stratigraphy and sedimentary architecture of the lishu depression in the songliao basin china the activity rate distribution and style of local faulting demonstrate the timing and extent of regional rifting distinct episodes of compressional tectonic activity caused uplift and exposure of strata evident as the traditional syn and post rift stages of basin evolution these episodes led to the sequential denudation of the upper jurassic huoshiling formation lower cretaceous yingcheng and denglouku formations and corresponding regional unconformities acting in tandem with regional compression activity along the major boundary faults influenced the evolving basin configuration as well as seismic sequences and sedimentary patterns seismic well log and drill core data described here show subdivision sections of the lishu depression strata according to discrete phases of the traditional syn rift stage of deposition we refer to these sub stages as the initial rifting the intensive rifting and the recession phases the basin configuration shifted from a graben half graben configuration during the initial rifting phase to a dustpan shaped half graben pattern during the subsequent phase of intensive rifting and finally into a gentle sedimentary basin during the final recession phase the early seismic sequence divides into a lowstand systems tract lst transgressive systems tract tst and highstand systems tract hst evidence of the lst within the seismic sequence becomes less apparent with the intensive rifting phase while the hst occupied an increasing proportion of the section the shallow water depositional fill formed during the final recession phase consists only of tst and hst components depositional environment then shifts from alluvial fan and shallow lacustrine systems to fan delta braided delta lake and finally to a braided fluvial setting the vertical stacking pattern shifts from retrogradational to progradational to aggradational identification of sub structural units and interpretation of their genetic relationships helps clarify basin evolution and thus serves larger scale continental basin analysis

a 750 year fire history based on lake sediment records in central yellowstone national park usa a 750 year fire history was reconstructed for the central plateau of yellowstone national park from the deep water sediments of five lakes the charcoal record from a large lake provided a chronology of regional fires data from four small lakes were used to study local and extralocal fires the co occurrence of abundant charcoal and high magnetic susceptibility values at the same stratigraphic level was used as evidence of a local catchment fire and a charcoal peak without high magnetic susceptibility was ascribed to an extralocal fire or a local fire without a related erosion event the fire history was compared with the dendrochronologic fire record for the last 450 years and the close agreement provided the justification to extend the chronology back in time large areas of the region burned in ad 1988 c 1700 c 1560 and c 1440 from c 1220 to 1440 and c 1700 to 1987 intermediate to small areas burned the near absence of fires in the twentieth century prior to the large fires of 1988 is evi

use of magnetic and radiometric measurements to investigate erosion and sedimentation in a british upland catchment in response to the potential shortcomings of single technique strategies in the investigation of erosion and sedimentation a combined magnetic and radiometric 13cs and 210pb approach has been undertaken in the upland watershed lake system of howden reservoir derbyshire by combining these techniques some assessment of sediment sources and the erosion status of the catchment has been achieved alone each approach would have been unable to determine unequivocally sediment provenance furthermore the parallel use of these measurements has highlighted limitations and or uncertainties in both the magnetic and 137cs techniques these problems reflect the particular soil characteristics and drainage conditions of this upland catchment despite the documented severity of peat erosion in the region howden reservoir has a mixture of sediment sources and a relatively moderate rate of sedimentation sediment yields total 127 7 t km 2 yr 1 including organic fraction 31 3 t km 2 yr 1 are however higher than in other british upland areas