a new record of holocene climate change from the bottom sediments of lake baikal abstract detailed siliceous microfossil records diatoms and chrysophyte cysts from the bdp 93 2 borehole with resolution of ca 30 120 years were obtained from lake baikal sediments to test the sensitivity of the lake baikal system to minor climate changes during the holocene our new results demonstrate that the subboreal period is characterized by the highest accumulations of diatom frustules and chrysophyte cysts in lake baikal sediments the siliceous microfossil record suggests that the holocene climatic optimum in this interior part of asia corresponds to the subboreal period 2 5 4 5 ka and not to the atlantic period 4 6 6 ka although quite different from holocene reconstructions for the european part of eurasia the holocene sedimentary record from lake baikal shows good correlation with palynological and soil climatic records from southeast siberia and mongolia where similar responses of the terrestrial biosphere are also documented a distinctive monospecific lamina of synedra acus diatom species coincident with the maximum of chrysophyte cyst accumulation during the subboreal period argues for the possible short term changes of the trophic state of lake baikal from oligotrophic with a cold water diatom assemblage to eutrophic with a thermophilic monospecific diatom flora comparison of diatom and cyst responses provides a key to distinguishing the humidity from temperature response in future studies of high resolution records of lake baikal

vegetation and climate dynamics during the holocene and eemian interglacials derived from lake baikal pollen records abstract the last interglacial li and holocene changes in annual precipitation p ann the mean temperature of the warmest t w and coldest t c month and the moisture index were reconstructed from continuous pollen records from lake baikal the holocene core 52 31 n 106 09 e presented in this study was recovered from a depth of 355 m in the 25 km wide underwater buguldeika saddle separating the southern sub basin of lake baikal from its central sub basin the biome reconstruction shows that tundra and steppe biomes have highest scores during ca 15 000 13 300 cal years b p and that taiga becomes a dominant vegetation type after ca 13 300 cal years b p our quantitative reconstruction indicates an onset of relatively warm and wet conditions soon after ca 10 000 cal years b p the warmest and wettest climate with t w 16 c p ann 480 mm and 0 9 1 has been reconstructed for ca 9000 7000 cal years b p in the lake baikal region this interval is characterized by the appearance and spread of hunter communities kitoi culture consistently a hiatus in the regional archaeological record 4900 4200 years b c or 6850 6150 cal years b p coincides with the interval of a major climate deterioration which followed the climatic optimum an attempt to find a relationship between the archaeological record and a spread of steppe and meadow communities in the lake baikal region demonstrates that despite a long habitation of the area the human impact on vegetation was local rather than regional and likely did not affect the pollen record from lake baikal the reconstructed peaks in the steppe biome scores during the last 9000 years are consistent with short one to five hundred year episodes of weak pacific summer monsoon supporting our interpretation that the holocene vegetation changes around lake baikal are associated with large scale circulation processes controlling regional water balance rather than with human activities thus our study proves the suitability of lake baikal pollen data for the reconstruction of natural vegetation and climate dynamics through the whole period from the onset of the li to the present comparison of the recent and the last interglacial suggests that the holocene climatic optimum was less pronounced e g lower summer and winter temperatures and annual precipitation sums than that of the li on the other hand pollen records demonstrate that the holocene forest phase already lasts some thousand years longer than that of the li the interglacial vegetation dynamics derived from the lake baikal pollen records can be satisfactorily explained by reconstructed changes in summer and winter temperatures and in available moisture the interglacial vegetation around lake baikal is dominated by the boreal forests which are associated with a generally warm and wet climate the high sea level associated with decreased ice volume appears to have had a greater impact on the siberian environments during the last and the recent interglacial than the direct effect of lower than present winter insolation reconstructed changes in the winter temperature correlate well with changes in the sea level and global ice volume while the summer temperatures derived from the lake baikal pollen records track changes in the summer insolation

climate signals in sediment mineralogy of lake baikal and lake hovsgol during the lgm holocene transition and the 1 ma carbonate record from the hdp 04 drill core abstract modeling the bulk sediment xrd patterns allows insight into the environmental and depositional histories of two neighboring rift lake basins within the baikal watershed parallel 14c dated lgm holocene records in lakes baikal and hovsgol are used to discuss the mineralogical signatures of regional climate change in both basins it is possible to distinguish glacial and interglacial mineral associations clay minerals comprise in excess of 50 of layered silicates in bulk sediment the abundance of smectite expandable layers in mixed layer illite smectites and the total illite abundance are the main paleoclimatic indices in the clay mineral assemblage both indices exhibit coherent responses to the bolling allerod and the younger dryas the smectite layer index is not equivalent to the abundance of illite smectite because illite smectite tends to transform into illite repeated wetting drying cycles in soils and high abundance of expandable layers in illite smectites 42 favor the process of illitization this relationship is clearly shown in both baikal and hovsgol records for the first time the opposite late holocene trends in illite abundance in lake baikal and lake hovsgol records suggest that a sensitive optimal regime may exist for illite formation in the baikal watershed with regard to warmth and effective moisture the lake hovsgol sediments of the last glacial contain carbonates suggesting a positive trend in the lake s water budget a progressive change towards lower mg content in carbonates indicates lowering mineralization of lake waters this trend is consistent with the lithologic evidence for lake level rise in the hovsgol basin the pattern of mineralogical changes during the past 20 ka is used to interpret bulk sediment and carbonate mineralogy of the long 81 m lake hovsgol drill core hdp 04 with a basal age of 1 ma the interglacial type silicate mineral associations are confined to several thin intervals most of the sediment record is calcareous carbonates are represented by six main mineral phases calcite low mg calcite intermediate high mg calcite dolomite excess ca dolomite and metastable monohydrocalcite these mineral phases tend to form stratigraphic successions indicative of progressive changes in lake water chemistry five sediment layers with abundant mg calcites in the hdp 04 section suggest deposition in a low standing lake with high mineralization salinity and high mg ca ratios of lake waters lake hovsgol sediments contain the oldest known monohydrocalcite found tens of meters below lake bottom in sediments as old as 800 ka this unusual find is likely due to the conditions favorable to preservation of this metastable carbonate

a 240 000 year stable carbon and nitrogen isotope record from a loess like palaeosol sequence in the tumara valley northeast siberia abstract a 15 m loess like palaeosol sequence located in the tumara valley southwest of the verkhoyansk mountains was investigated to reconstruct the late quaternary environmental history of northeast siberia total organic carbon toc and total nitrogen n show several distinct and abrupt shifts during the last 240 ka both proxies have generally low values

loessial soils of priangaria transbaikalia mongolia and northwestern china abstract comparative analysis of loessial soils from priangaria transbaikalia western mongolia and northwestern china investigated the differences in genesis microstructure plasticity and swelling and collapsibility priangarian loess like deposits formed through a combined model where during sedimentation individual primary layers of aeolian origin were deposited in a general background of deluvial deposits successive strata with differing aeolian additions were the media for soil formation microstructure is aggregated skeletal in all areas there is a similarity between the microstructure parameters and the structural model of the loessial soils of priangaria and northwestern china and between soils of transbaikalia and western mongolia the mineral composition particularly smectite and the coefficient of freedom of the fine clay fraction are the factors controlling swelling the loessial soils of transbaikalia western mongolia and northwestern china exhibit collapsibility in priangaria the manifestation of this property is different resulting from the climatic zonation and the differences in genesis

genesis and properties of black soils in buryatia southeastern siberia russia abstract soils with deep and dark brown to black humic surface horizons derived from sandy silty aeolian and alluvial sediments are relatively fertile and store huge amounts of carbon globally they mainly correlate with steppe ecosystems because their deep and dark epipedons are frequently rich in black carbon it was recently suggested that they developed due to prevalent burning of the semiarid vegetation this paper describes six soils with deep and dark humic surface horizons located in catchments of the selenga and uda rivers in buryatia southeastern semiarid siberia the organic matter of most of these soils not only originates from grass steppe but in addition from trees and shrubs five soils can be classified as chernozems and kastanozems wrb 2006 one soil is a deep and black anthrosol occurring in patches in the region all soils have calcic horizons below the mollic epipedon some with cambic bw horizons in between as the parent material does not contain carbonates aeolian input and hydrolysis of ca silicates contribute to the development of the secondary carbonate accumulation which is frequently cryoturbated all profiles are more or less stratified due to solifluction texture ratios 2 al 2 o 3 and al 2 o 3 100 al 2 o 3 na 2 o increased concentrations of tio 2 mgo and fe 2 o 3 presumably indicate advanced formation of chlorite radiocarbon analyses indicate that these deep and dark mollic horizons started to develop during the more humid holocene climatic optimum ca 7000 5000 bp palynological studies confirm expansion of forests in the lake baikal region in this period this is in agreement with higher alkane ratios nc27 nc31 in most of the deep and dark a horizons indicating that these epipedons diagnostic for chernozems and kastanozems did not develop exclusively under grass steppe thus supporting the hypothesis that a significant part of the soil organic matter is inherited from trees and shrubs this seems to be in contrast to middle europe and the russian plain where chernozems presumably developed during the early and mid holocene under grass steppe and subsequent degraded with increasing humidity and invasion of forests high contents of black carbon in the calcic chernozem p4 and lower ones in the long lasting occupied hortic anthrosol indicate that the deep and dark a horizons of mollisols most likely do not result from frequent burning but from biochemical processes

magnetic enhancement is linked to and precedes hematite formation in aerobic soil 1 soil formation usually increases magnetic susceptibility most often by increasing the concentrations of magnetite and maghemite which are two ferrimagnetic iron oxides here we provide evidence that magnetic enhancement in aerobic soils not affected by detrital magnetic inputs or thermal transformation of other iron oxides is mostly due to the formation of maghemite which is later transformed into hematite the iron oxide that gives red color to soil we show that the maghemite hematite ratio is influenced by the particular environment and the degree of soil development so it constitutes an effective tool for paleoenvironmental and planetary studies

geochronological and geochemical constraints on the origin of the yunzhug ophiolite in the shiquanhe yunzhug namu tso ophiolite belt lhasa terrane tibetan plateau abstract the formation of the shiquanhe yunzhug namu tso ophiolite melange zone snmz within the lhasa terrane tibetan plateau is key to understanding the mesozoic tectonic evolution of this terrane which remains controversial we show that the yunzhug ophiolite in the central segment of the snmz formed at 150 ma based on u pb dating of zircons from a gabbroic sample in a well developed sheeted dike complex geochemically these mafic rocks are dominated by e morb type compositions along with minor amounts of rocks with p morb type compositions the samples also exhibit high end t values and lack negative nb and ta anomalies data for all the samples plot within the morb array on a th yb nb yb diagram therefore these mafic rocks most likely formed in either a slow spreading oceanic setting or an embryonic ocean and not in a back arc basin as has been previously assumed taking into account the regional geology we propose that the yunzhug ophiolite is part of a distinct ophiolitic belt and represents material formed in an embryonic ocean within the lhasa terrane which provides new insights into the jurassic tectonic evolution of the lhasa terrane

geology and fauna and preliminary correlation of sediments of the main late cenozoic sites of the transbaikal area abstract the pliocene and pleistocene sediments exposed in eight sections of transbaikalia have been correlated using geological and palynological data together with information on fossil mammals and some paleomagnetic characteristics the most complete sequence of fossiliferous deposits spanning the time interval from the middle pliocene to the late pleistocene is exposed in the tologoi key section the sequence was correlated with other sections primarily on the basis of mammal faunas during deposition of the chikoi suite udunginian chikoian and itantsinian faunal complexes appeared in succession four successive stages in mammal evolution are recognized within the early pleistocene deposition of the krivoyarskaya suite proceeded throughout the time when the tologoi faunistic complex ivolginian and other pleistocene faunas followed each other in the transbaikalian region

aerosol size confines climate response to volcanic super eruptions extremely large volcanic eruptions have been linked to global climate change biotic turnover and for the younger toba tuff ytt eruption 74 000 years ago near extinction of modern humans one of the largest uncertainties of the climate effects involves evolution and growth of aerosol particles a huge atmospheric concentration of sulfate causes higher collision rates larger particle sizes and rapid fall out which in turn greatly affects radiative feedbacks we address this key process by incorporating the effects of aerosol microphysical processes into an earth system model the temperature response is shorter 9 10 years and three times weaker 3 5 k at maximum globally than estimated before although cooling could still have reached 12 k in some midlatitude continental regions after one year the smaller response plus its geographic patchiness suggests that most biota may have escaped threshold extinction pressures from the eruption

paleoenvironmental proxy records from lake hovsgol mongolia and a synthesis of holocene climate change in the lake baikal watershed abstract here we discuss paleoenvironmental evolution in the baikal region during the holocene using new records of aquatic diatom and terrestrial vegetation changes from hovsgol mongolia s largest and deepest lake we reconcile previous contradictory baikal timescales by constraining reservoir corrections of ams dates on bulk sedimentary organic carbon synthesis of the holocene records in the baikal watershed reveals a northward progression in landscape vegetation changes and an anti phase behavior of diatom and biogenic silica proxies in neighboring rift lakes in lake baikal these proxies appear to be responsive to annual temperature increases after 6 ka whereas in lake hovsgol they respond to higher precipitation runoff from 11 to 7 ka unlike around lake baikal warmer summers between 6 and 3 5 ka resulted in the decline not expansion of forest vegetation around lake hovsgol apparently as a result of higher soil temperatures and lower moisture availability the regional climatic proxy data are consistent with a series of 500 yr time slice holocene gcm simulations for continental eurasia our results allow reevaluation of the concepts of the holocene optimum and a maximum of the asian summer monsoon as applied to paleoclimate records from continental asia

lacustrine and eolian records of holocene climate changes in the mongolian plateau preliminary results abstract this study compares two pairs of adjacent lacustrine and eolian sections at sites in the southern and northern mongolian plateaus in order to test spatial climate variability during the holocene based on the lithology proxy data and 14 c dated and the interpolated ages the following observations can be made in the northern mongolian plateau a best developed holocene paleosol dated at 8672 14 c yr bp at the shaamar section and the carbonate rich laminated layer in the gun nuur lake core mark the interval of warmer and dryer climate during the early holocene younger paleosols at the shaamar section and corresponding organic rich layers in the gun nuur core were formed under distinctly cooler and more humid conditions the baahar nuur lake core in the southern mongolian plateau and the dingxi type section in the northern part of the western chinese loess plateau appear to indicate that a prolonged interval of maximum humidity prevailed in this region during the early and mid holocene 9000 4000 14 c yr bp by contrast in the northern mongolian plateau the most humid conditions seem to have occurred from 4500 to 2500 possibly to 1650 14 c yr bp this discrepancy implies that the concept of the holocene climatic optimum has limitations and may have to be reconsidered if it is intended to have a large scale connotation

radiocarbon age of holocene paleosols of the east european forest steppe zone abstract comparison of the radiocarbon ages of soils buried under previously dated burial mounds with those of surface background soils in surrounding areas indicates the rate of humus renewal and aids the dating of paleosols buried soils and relic horizons in surface soils together with evidence for the development of soils of watersheds in the holocene the soils of depressions indicate reactivation of erosion processes in the last 3 8 centuries agricultural erosion there is also evidence of erosion during the periods of 7 8 ka and 4 5 ka bp which was associated with abrupt climatic and environmental changes

pleistocene climate change natural environments and palaeolithic occupation of the angara baikal area east central siberia abstract diversity of the relief and the pleistocene environments of the mountain areas of sw siberia played a major role in the history of the palaeolithic peopling of this territory the geographical and contextual distribution of the cultural records reflects a climatic instability in the altai area palaeoenvironmental proxy data indicate that the natural conditions during the earlier stages were generally more favourable for early human occupation than during the later stages the cyclic nature of the glacial and interglacial periods led to periodic landscape transformations and generation of specific ecosystems adjusted to particular topographic settings and responding to climatic variations the initial occupation of the broader altai region associated with pebble tool industries from alluvial formations likely occurred during some of the middle pleistocene interglacials accompanying the northern expansion of the temperate zone and biota mixed coniferous and broadleaf forests established in the tectonically active mountain zone with elevations of 1500 2000 m and parklands in the adjacent plains and continental basins provided a wide range of occupation habitats there is limited evidence for persistence of early palaeolithic inhabitation during glacial stages due to inhospitable periglacial conditions the last interglacial warming indicated by re colonization of southern siberia by coniferous taiga forests is linked with the appearance of the mousterian tradition changes in the relief configuration influenced the local climate regime and opened new habitats for the middle palaeolithic population concentrated in the transitional zones of 500 1000 m elevation in the karstic area of the nw altai foothills occupation of the central and southern altai during the early last glacial was impeded by harsh ice marginal environments and expansion of glaciers in the valleys filled by large proglacial lakes progressive warming during the early mid last glacial interstadial stage 59 35 ka bp caused wasting of the ice fields accompanied by cataclysmic releases of ice dammed lakes and large scale erosional processes periodic outbursts of the glacial basins had a dramatic impact on the regional ecosystems also obliterating the earlier cultural records appearance of the transitional early late palaeolithic stone industries reflects adaptation to mosaic interstadial habitats including sub alpine forest dark coniferous forest mixed parklands and open steppe the identical geographical distribution of the middle and late palaeolithic sites and the time transgressive lithic technologies suggest a regional cultural and biological continuity in the broader altai area during the late pleistocene re establishment of cold tundra steppe and tundra forest habitats correlates with the late palaeolithic horizon with developed stone industries dominated by blade flaking techniques these techniques possibly survived in more protected locations characterized by warm microclimates in the northern altai throughout the last glacial maximum 20 18 ka bp emergence of the microlithic assemblages with wedge shape cores is linked with a new cultural adjustment in the final stage of the palaeolithic development responding to transformations of the former periglacial ecosystems towards the end of the pleistocene

magnetic properties of modern soils and quaternary loessic paleosols paleoclimatic implications the magnetic properties of paleosols developed in quaternary sequences of loess have been used for stratigraphic definition correlation with other terrestrial and deep sea sequences and paleoclimatic paleorainfall reconstruction in some loess paleosol sequences including those of the chinese loess plateau tajikistan and the czech republic maxima in magnetic susceptibility values correspond with the paleosol horizons and minima with the least weathered loess layers in other loess soil sequences including those of siberia alaska and argentina the relationship is completely opposite with susceptibility minima associated with the most developed paleosols to account for these opposite relationships the respective roles of 1 magnetic enhancement and 2 magnetic depletion and or dilution in determining soil magnetic properties are investigated for a range of modern soil types most magnetic enhancement is seen in the upper horizons of well drained cambisols absence or loss of magnetic iron oxides is apparent in acid podsol profiles and waterlogged soils for the cambisol profiles significant correlation is found between susceptibility and organic carbon cation exchange capacity and clay content the mineralogy morphology and grain size of soil magnetic carriers extracted from three modern enhanced soils and a paleosol from the chinese loess plateau are also identified by independent petrographic means microscopy and x ray diffraction of magnetic extracts magnetite and maghemite of ultrafine grain size from 0 4 to 0 001 i m are the major contributors to the magnetically enhanced soils weathering can concentrate detrital magnetic grains especially in the fine silt size fractions of soils the magnetic data from the modern soils indicate that interpretation of paleosol magnetic properties must be done on a site specific basis taking into account the possibilities of pedogenic enhancement pedogenic dilution or depletion and allochthonous inputs of magnetic minerals excessively arid wet or acid soils are unable to form significant amounts of pedogenic ferrimagnets well drained intermittently wet dry soils with reasonable buffering capacity and a substrate source of fe show most magnetic enhancement for those soils which favour magnetic enhancement processes correlation has been found between the maximum value of the pedogenic susceptibility and the annual rainfall the almost unique pedogenic system in the chinese loess plateau where variation in soil forming factors other than climate is reduced to a global minimum allows use of the paleo susceptibility values as proxy paleorainfall values to identify the mechanism of any link between magnetic properties for example susceptibility and climate change the mineralogy and grain size of soil magnetic carriers requires detailed investigation given the prospect of 1 quantitative paleorainfall records from continental loess records 2 predictions of present and future climate change and 3 the value of paleoclimate data for testing of numerical climate models such magnetic investigations can contribute significantly to our understanding of past and future environmental change

paleoenvironments of palaeolithic humans in the baikal region abstract during the last 25 years abundant material on small mammals has been obtained from numerous pleistocene archaeological sites caves and open localities in the baikal region most small mammal fauna localities are dated to sartan time 23 000 10 000 bp with some attributed to karginsk time 50 000 23 000 bp paleontological studies provided a considerable amount of information on environmental changes both in transbaikalia and in the fore baikal region during palaeolithic and mesolithic since the end of middle pleistocene

reconstruction of postglacial to early holocene vegetation history in terrestrial central europe via cuticular lipid biomarkers and pollen records from lake sediments high resolution environmental reconstruction for central european terrestrial settings is commonly based on sediment records that provide the pollen spectra used for reconstruction of vegetation development alternatively complementary algal insect or zooplankton assemblages and or carbonate 18 o isotope profiles are investigated in this study vegetation development and inferred climate evolution were documented on a decadal to centennial scale by analysis of land plant cuticular lipids accumulated in lake sediments wax lipids derived from land plant leaves and blades are source diagnostic and highly resistant to degradation their aerodynamic properties favor short distance eolian transport but they are less affected by possible long distance transportation that complicates pollen analysis the late glacial to holocene sedimentary record of lake steisslingen southwestern germany was investigated by palynological and geochemical means tundra type pioneer vegetation consisting predominantly of grasses and herbs is dominated by nc31 alkanes whereas pioneer birch forest yields preferentially nc27 alkanes establishment of a pine assemblage is recognizable by elevated nc29 and nc31 leaf wax alkanes and the diversification of deciduous forests in the holocene is marked by nc29 dominance lipid geochemistry and palynology resolve decadal excursions such as the mid younger dryas event centennial climate trends with pronounced and rapid changes at the oldest dryas bolling allerod younger dryas and younger dryas preboreal transitions are consistently reflected by molecular and palynological proxy data the demonstrated suitability of an independent molecular proxy in paleoenvironmental studies provides new perspectives in high resolution climate reconstruction

metamorphic control of the magnetic mineralogy of black shales in the swiss alps toward the use of magnetic isogrades abstract the magnetic susceptibility of the helvetic jurassic black shales sampled around the aar and gothard massifs in the swiss alps is due to iron bearing silicates magnetite or pyrrhotite it exhibits a clear correlation with the alpine metamorphism from zeolite to amphibolite facies it firstly decreases due to the breakdown of original magnetite then sharply increases when pyrite is transformed into magnetic pyrrhotite using numerous field measurements of the susceptibility it was possible to carry out a fast and precise mapping of the pyrrhotite in isograde which appears to correspond closely to the stilpnomelane out isograde the matrix susceptibility obtained by means of high field measurements with a cryogenic magnetometer is due to iron bearing silicates and shows only smooth variations with metamorphism both monoclinic and hexagonal pyrrhotites are observed in the high grade area

clays and secondary minerals as permafrost indicators examples from the circum baikal region abstract a proper understanding of quaternary environments requires assessment of the possible existence of perennially frozen ground furthermore the structural and mineralogical changes induced by permafrost are commonly irreversible and still affect the present soils so that it is important to be able to recognize them however the regions that suffered severe but dry periglacial conditions during cold quaternary periods as in southeastern siberia show few periglacial features five exposures investigated in the circum baikal area show permafrost features although the same phenomena occur throughout southeastern siberia these exposures demonstrate that even though evidence of permafrost may be lacking or equivocal thorough analysis can reveal indicators of permafrost such as neoformed clays secondary precipitates of iron calcite and sulphates with peculiar crystalline features as are found in other past or presently perpetually frozen ground in combination with sedimentary structures and the geomorphic environment these indicators affirm the definite existence of permafrost

post glacial history of siberian spruce picea obovata in the lake baikal area and the significance of this species as a paleo environmental indicator abstract the relative abundances of siberian spruce picea obovata and total arboreal pollen in pollen spectra from the lake baikal region and calculation of a steppe forest vegetation index place constraints on the past climatic conditions related to permafrost summer temperatures precipitation and soil moisture availability here we review the data on picea pollen in sub recent spectra the present day distribution of picea obovata and sedimentary records from a number of sites to arrive at a coherent picture of evolution of regional vegetation since the late glacial the expansion of siberian spruce along with steppe vegetation dates back to the undivided bolling allerod interval when this species became dominant in arboreal vegetation steppe landscapes persisted in a large part of the lake baikal watershed prior to 9 2 9 ka when the expansion of arboreal vegetation took place following the younger dryas which seems to have had little effect on regional vegetation and peat accumulation the role of siberian spruce steadily declined until 8 6 6 8 ka in the late holocene the abundance of p obovata rarely exceeded the present day ratio of ca 2 total arboreal pollen departures towards higher picea abundance and higher steppe forest index at ca 6 5 and 3 2 5 ka in selenga delta area appear to reflect periods with decreased temperatures and higher moisture availability in the southern part of the lake baikal watershed