changes in antarctic bottom water properties in the western south atlantic in the late 1980s data collected in 1988 1989 as part of the south atlantic ventilation experiment have been combined with the historical database to study the circulation and water mass variability of the abyssal water in the argentine basin a map of potential temperature at 4000 m used as an indication of geostrophic shear defines a south and western intensified crescent shaped abyssal recirculation within this recirculation and its northward extension to the brazil basin antarctic bottom water aabw properties have undergone two modifications during the 1980s 1 the water mass cooled 0 05 c and freshened 0 008 in salinity ratio on surfaces of constant density 2 the densest layer of aabw was altered to less dense water through mixing or advection out of the study area this water mass change does not appear to have affected the flow pattern data collected in 1983 and 1988 to the north in the brazil basin show penetration of the freshwater mass in the deep western boundary current to between 18 s and 10 s indicating very rapid propagation of the anomaly from the argentine basin into the brazil basin as a deep western boundary current it is suggested that open ocean convective events within the weddell sea contributed to the change in aabw documented here

organic geochemical proxies of paleoceanographic paleolimnologic and paleoclimatic processes abstract organic matter constitutes a minor fraction of marine and freshwater sediments yet its important contribution to the sedimentary record can be used to reconstruct marine and continental paleoenvironments the organic matter content of sediments is the residue of past biota the amounts and types of organic matter present in sediments consequently reflect environmental conditions that impacted ecosystems at different past times general sources of the organic matter are inferred from bulk properties such as elemental compositions carbon and nitrogen stable isotope ratios rock eval pyrolysis data and organic petrography details of organic matter origins are refined by analyses of biomarker molecular compositions source changes are proxies for fluctuations in sea level oceanic surface currents and continental climates algal paleoproductivity rates are indicated by organic carbon mass accumulation rates and carbon and nitrogen stable isotopic compositions these parameters record past availability of nutrients and therefore are proxies of surface mixing in the oceans and amount of land runoff to lakes sea surface paleotemperatures are recorded by the number of carbon carbon double bonds in lipid biomarkers produced by marine algae larger proportions of the double bonds are proxies for the cooler surface waters that accompanied periods of global glaciation and intervals of enhanced upwelling the 13c and d values of plant organic matter record past concentrations of carbon dioxide in the atmosphere and changes in delivery of atmospheric moisture respectively diagenesis which causes the concentration and composition of organic matter in sedimentary settings to differ from those of the original biologically synthesized materials can bias organic geochemical paleoenvironmental records the magnitude of this potential source of misinformation must always be considered and evaluated comparison of multiple organic geochemical proxies of past conditions helps to compensate for the effects of diagenetic alterations and thereby to improve interpretations of paleoenvironmental change

historical changes in organic matter input to the muddy sediments along the zhejiang fujian coast china over the past 160 years abstract the burial of sedimentary organic matter som in large river influenced estuarine coastal regions is affected by hydrodynamic sorting diagenesis and human activities typically the inner shelf region of the east china sea is a major carbon sink for the yangtze river derived fine grained sediments most of the previous work concentrated on studies of surface sediments or used a single proxy in this region in this study two cores from the zhejiang fujian coast were analyzed using bulk toc tn and 13 c toc and molecular biomarker n alkane brassicasterol dinosterol and glycerol dialkyl glycerol tetraether lipids techniques to clarify the sources spatiotemporal distribution and fate of som in the yangtze river estuary and adjacent shelf results indicated that the effects of diagenesis and diffusion on different sedimentary biomarkers resulted in overestimation of the relative contribution of terrestrial organic matter om terr compared with those based on 13 c toc the amount of terrestrial plant organic matter om plant and om terr in sediments decreased offshore in contrast the amount of marine organic matter om marine increased offshore but closer to the yangtze river mouth the amount of soil organic matter om soil increased moreover the amounts of toc om plant and om marine biomarkers increased but om soil and om terr decreased over time in recent decades our study suggests that spatial om distribution patterns in marine shelf sediments were controlled primarily by hydrodynamic sorting and nutrient concentration and temporally diverse patterns were controlled predominantly by anthropogenic influence e g dam construction and soil conservation reclamation and agricultural plantations anthropogenic nutrient input dust storms eutrophication etc and climate events e g interdecadal climatic jump and heavy rain events in the geological period

the flux and mixing rates of antarctic bottom water within the north atlantic calculation was made of the northward flow of antarctic bottom water into the western north atlantic basin through a passageway approximately 300 km wide between the ceara rise and the mid atlantic ridge at about 4 n two moorings carrying four current meters each were placed in the region where currents were expected to be the greatest and were left for 360 days the current was not steady but exhibited large surges with approximately a 60 day time scale whose cause is unknown current meters in the fastest flowing region all exhibited a net northward flow it is estimated that approximately 0 8 106 m3 s 1 of water colder than 1 9 c potential temperature flowed on the average into the north atlantic with this number possibly being too small by 0 3 106 m3 s 1 or too big by 0 1 106 m3 s 1 depending upon estimates of the width of the region which the current meters sample however these numbers differ from geostrophic estimates of 1 98 106 m3 s 1 the disagreement coming almost entirely from the fact that the geostrophic estimates give a sizeable flux of water colder than 1 2 c while the current meters do not based upon the two different flux rates residence times and mixing coefficients are calculated for antarctic bottom water for each 0 1 c potential temperature interval from 1 0 c to 1 9 c finally some comments on the dynamics of the northward flow are made

man s influence on the erosion and transport of sediment by asian rivers the yellow river huanghe example during the holocene sediment input from the yellow river to the yellow sea and adjacent areas has amounted to about 3000 km 3 detailed records from river gauging stations over the past 70 yrs together with estimates based on earlier historic records suggest that the river has contributed 2300 km 3 of sediment during the last 2300 yrs an average discharge of 1 km 3 yr 1 x 10 9 t yr prior to extensive agricultural use of the loess plateau in northern china beginning about 200 bc therefore the river s load must have been about 0 1 km 3 yr an order of magnitude lower than that at present a broad delta 20 m below sea level suggests that early holocene rates were higher than the pre agricultural average and therefore that middle holocene loads were low

high resolution reconstruction of sedimentary organic matter variability during the holocene in the mud area of the yellow sea using multiple organic geochemical proxies abstract as a result of terrestrial input and local circulation an area containing continuously deposited mud with abundant organic matter om has formed in the yellow sea ys off the shandong peninsula china during the holocene the understanding of temporal variations in sedimentary organic matter som from this mud area helps to evaluate the influences of yellow river discharge and marine productivity on the burial of organic matter in the ys in this study multiple organic geochemical proxies were used to reconstruct holocene changes in som in a sediment core a02c recovered from the mud area of the ys higher total organic carbon toc and biomarker contents during the early holocene relative to the middle and late holocene are attributed to sea level fluctuations the 13c values of toc 13ctoc range from 21 8 to 23 5 becoming more positive from the bottom to the top of the core tmbr terrestrial and marine biomarker ratio values vary from 0 43 to 0 80 with a decreasing trend during the holocene the decrease in tom contribution was related to elevated sea level shifting of the mouth of the yellow river and weakening of the east asian winter monsoon eawm during the holocene a mixing model with three end members based on 13ctoc and tmbr reveals that the contribution of soil om average 42 is higher than that of plant om average 17 simultaneous decreases in the plant om fraction and the marine om fraction occurred around 10 3 8 2 5 9 4 2 and 2 8 kyr bp corresponding to drift ice events in the north atlantic spectral analyses also reveal that all three om fractions exhibit 1015 year periodicity and that the soil and plant om fractions display 1420 year periodicity consistent with the 1000 year cycle of solar activity and the 1500 year cycle of the kuroshio current kc respectively

a novel proxy for terrestrial organic matter in sediments based on branched and isoprenoid tetraether lipids we propose a novel tracer for terrestrial organic carbon in sediments based on the analysis of tetraether lipids using high performance liquid chromatography mass spectrometry hplc ms analysis of terrestrial soil and peats shows that branched tetraether lipids are predominant in terrestrial environments in contrast to crenarchaeol the characteristic membrane lipid of non thermophilic crenarchaeota which is especially abundant in the marine and lacustrine environment based on these findings an index was developed the so called branched and isoprenoid tetraether bit index based on the relative abundance of terrestrially derived tetraether lipids versus crenarchaeol this bit index was applied to surface sediments from the angola basin where it was shown to trace the outflow of the congo river furthermore analyses of particulate organic matter from the north sea showed relatively higher bit indices in water column particulate organic matter near large river inputs a survey of globally distributed marine and lacustrine surface sediments shows that the bit index in these environments correlates with the relative fluvial input of terrestrial organic material making this index generally applicable the new proxy allows the rapid assessment of the fluvial input of terrestrial organic material in immature sediments up to 100 ma old

cold outflow from the faroe bank channel abstract the exchange of water between the norwegian sea and the north atlantic around the faroe islands was investigated in 1987 and 1988 combining ctd data with shipborne acoustic doppler current profiler adcp measurements tests were devised to assess the accuracy of the adcp measurements and the results are described it is found that estimating a reference velocity for geostrophic measurements is limited by the presence of tides of order 10 cm s 1 in the outflow of cold water from the faroe bank channel which reaches speeds of nearly 1 m s 1 the error is acceptably small but strong time dependent components are revealed the discharge of cold water is traced 75 km beyond the sill of this channel and changes in potential temperature salinity and potential vorticity on an isopycnal surface are attributed to intense mixing an effective diffusivity near 100 cm2 s 1 is derived and k h instability demonstrated as a plausible source of the turbulent energy six current meter moorings were deployed from

fluxes and distribution of tetraether lipids in an equatorial african lake constraints on the application of the tex86 palaeothermometer and bit index in lacustrine settings abstract the distribution of isoprenoid and branched glycerol dialkyl glycerol tetraether gdgt lipids was studied in material from various sources in and around lake challa a crater lake on the southeastern slope of mt kilimanjaro tanzania to examine the provenance of gdgts in lake sediments and their potential application as palaeoenvironmental and palaeoclimatic proxies the study material included samples collected at monthly intervals in a sediment trap over one complete annual cycle particles suspended in the stratified water column profundal surface sediments and soils surrounding the lake the sediment trap time series revealed that crenarchaeol and related isoprenoid gdgts were predominantly produced in january and february following the locally prominent short rain season november december the tex 86 inferred temperature derived from sedimenting particles corresponded well with lake surface water temperature at this time of largest crenarchaeol flux molecular ecological analysis showed that group 1 1a and 1 1b crenarchaeota are the most likely source organisms of these gdgts gdgt 0 in the lake sediments does not only originate from lake surface dwelling crenarchaeota but seems predominantly derived from archaea residing in the deeper anoxic part of the water column the main flux of branched gdgts to the sediment was during the short rain season and is most probably derived from eroded catchment soils in surface run off however a contribution from in situ production of branched gdgts in the lake sediment or water or in groundwater cannot be fully excluded we conclude that palaeoclimatic reconstruction based on branched gdgt distributions in lake sediments should only be performed when the origin of those branched gdgts is well constrained

variability of antarctic bottom water flow into the north atlantic abstract the flow of antarctic bottom water from the brazil basin in the south atlantic into the guiana basin in the western north atlantic has been measured by current meters for 44 months flow is confined by a relatively flat 4500 m deep passage between 1 s and 4 n with complex sidewall shape at the southern end is a 300 km wide zonal channel straddling the equator between 32 w and 38 w with approximately a 500 m deep layer of bottom water the deep antarctic bottom water current into the north atlantic is confined to a region south of the equator and the direction is westward previous measurements of this deep current over 600 days in duration j phys oceanogr 27 1997 1903 indicated both a small warming trend and a decreasing volume flux new data presented in this paper of 1388 days duration show no evidence for continuation of such trends the average temperature and yearly averaged velocities are about the same as earlier at revisited locations the long term drift of the deep antarctic bottom water temperature is about 0 002 c year and drift of the westward velocity is about 0 0015 m s year the greatest variability is found near the top of the deep antarctic bottom water at the northern edge of the current the spectrum of the new 44 month data reveals a distinct yearly peak we conclude that there has been no change in antarctic bottom water flux into the north atlantic during the past decade

comparative molecular biomarker assessment of phytoplankton paleoproductivity for the last 160 kyr off cap blanc nw africa abstract we report high resolution molecular abundance data for alkenones dinosterol long chain diols and n alkanols from odp site 658 20 45 n 18 35 w 2263 m water depth these data are compared with previously reported data for toc chlorins opal and long chain n alkanes the contents and mass accumulation rates mars of chlorins are used as total phytoplankton productivity proxies while the contents and mars of opal dinosterol alkenones and diols are used as productivity proxies for diatoms dinoflagellates haptophytes and eustigmatophytes diatoms respectively five high productivity intervals hpis are identified two at the glacial interglacial transition boundaries of 132 122 and 15 8 ka two within the warmer periods of mis 3 50 30 ka and the late holocene 4 0 ka and one within the glacial period of mis 4 67 60 ka productivity was lowest during both the penultimate glacial maximum of mis 6 150 140 ka and the last glacial maximum 22 18 ka as revealed by both the total phytoplankton and individual phytoplankton productivity indicators phytoplankton community structure changed significantly over the last 160 kyr the termination i ii hpis were characterized by higher opal content possibly reflecting increased diatom contributions to total productivity eustigmatophyte diatom and haptophyte contributions were higher during mis 5 but decreased toward the holocene dinosterol revealed an opposite trend with the highest contribution in the holocene we ascribe such changes in phytoplankton communities to the effects brought about by the varying amounts and nature of nutrient inputs contributed regionally by eolian dusts river influxes ocean currents and upwelling water masses

distributions and origins of lipid biomarkers in surface sediments from the southern yellow sea abstract this paper reports on the spatial distribution patterns and investigates the controlling mechanisms of phytoplankton biomarkers brassicasterol for diatoms alkenones for haptophytes dinosterol for dinoflagellates and terrestrial biomarkers odd c number long chain c 27 c 29 c 31 n alkanes in surface sediments from the southern yellow sea sys the contents of the phytoplankton biomarkers in the sys surface sediments reveals a clear spatial pattern with low values near the coasts and increased values seaward caused by higher phytoplankton primary productivity and low sedimentation rates in the basin the contents of terrestrial biomarkers show high values in the northern part of the study areas off the shandong peninsula and jiangsu coast caused by inputs of materials from the modern huanghe river and the old huanghe delta respectively the results also indicate that biomarker ratios offer the best approach for reconstructing marginal sea c cycles as these proxies can be used to estimate the contributions of both terrestrial and marine organic matter and to reconstruct paleoproductivity and paleoecological changes in the sys

sources and distributions of tetraether lipids in surface sediments across a large river dominated continental margin glycerol dialkyl glycerol tetraether gdgt based proxies are increasingly used in modern carbon cycling and palaeoenvironmental investigations it is therefore crucial to examine the robustness sources transport and degradation of all gdgt based proxies in continental margins where sedimentation rates and extent of carbon cycling are high we have analyzed the distributions of gdgts in surface sediments from the lower yangtze river and east china sea ecs shelf the results revealed multiple sources and complex shelf processes that govern the distributions the isoprenoid gdgt inferred sea surface temperatures ssts are robust and reflect the satellite derived annual mean ssts on the shallow ecs shelf confirming an origin from surface water column dwelling crenarchaeota the input from methanogen sourced isoprenoid gdgts is significant in the river surface sediments but they are almost absent from the ecs shelf branched gdgts are also abundant in the river sediments but ca 95 are degraded in the yangtze estuary a much greater extent than observed for other terrigenous organic matter om proxies there is also evidence for production of branched gdgts in the oxic ecs shelf water column and the anoxic sediments waters of the lower yangtze river as a result branched gdgt based proxies in the lower river and ecs surface sediments do not reflect the catchment environmental conditions the effective degradation in the estuary and widespread aquatic contributions of branched gdgts improves our understanding of how to use branched gdgt based proxies in marginal seas

constraints on the application of the mbt cbt palaeothermometer at high latitude environments svalbard norway abstract branched glycerol dialkyl glycerol tetraethers gdgts are membrane lipids of unknown bacteria that are ubiquitous in soil and peat two indices based on the distribution of these lipids in soils the cyclization of branched tetraethers cbt and the methylation of branched tetraethers mbt indices have been shown to correlate with soil ph and mean annual air temperature mat and soil ph respectively and can be used to reconstruct mat in palaeoenvironments to verify the extent to which branched gdgts in marine sediments reflect the distribution pattern on land and whether these proxies are applicable for palaeoclimate reconstruction in high latitude environments with a mat of

constraints on the sources of branched tetraether membrane lipids in distal marine sediments abstract branched glycerol dialkyl glycerol tetraethers brgdgts are membrane lipids produced by soil bacteria and occur in near coastal marine sediments as a result of soil organic matter input their abundance relative to marine derived crenarchaeol quantified in the bit index generally decreases offshore however in distal marine sediments low relative amounts of brgdgts can often still be observed sedimentary in situ production as well as dust input have been suggested as potential though as yet not well constrained sources in this study brgdgt distributions in dust were examined and compared with those in distal marine sediments dust was sampled along the equatorial west african coast and brgdgts were detected in most of the samples albeit in low abundance their degree of methylation and cyclisation expressed in the mbt methylation index of branched tetraethers and dc degree of cyclisation indices respectively were comparable with those for african soils their presumed source comparison of dc index values for brgdgts in global soils congo deep sea river fan sediments and dust with those of distal marine sediments clearly showed however that distal marine sediments had significantly higher values this distinctive distribution is suggestive of sedimentary in situ production as a source of brgdgts in marine sediments rather than dust input the presence of in situ produced brgdgts in marine sediments means that caution should be exercised when applying the mbt cbt palaeothermometer to sediments with low bit index values i e

sources dispersal and preservation of sedimentary organic matter in the yellow sea the importance of depositional hydrodynamic forcing abstract the sources distribution and fate of sedimentary organic matter som in the yellow sea ys were studied based on the datasets of total organic carbon toc total nitrogen tn organic carbon isotopic values 13 c and n alkanes of forty seven surface sediment samples the spatial pattern of toc and tn coincided with that of the sediment grain size suggesting the hydrodynamic constraints on the accumulation of som in the ys the relatively low toc tn ratios with contrasting tn intercept of the regression lines indicate the influence of the sorption of inorganic n in the nys and a mixture of microorganism derived n rich om pool with the terrigenous n poor om for the sys sediment samples respectively the enriched 13 c could also be partially related to the agriculture inputs due to the enhanced fertilization process in addition to the planktonic derived om molecular compositions of n alkanes and principal component analysis pca showed a significant terrigenous contribution for the som in the central mud deposits the observed even carbon preference of the short chain length n alkanes c 12 c 22 reveals the potential contribution of microorganism derived om in the ys combined lines of evidence of significant terrigenous n alkanes in the ys suggest that the hydrodynamic forcing plays a key role on the selective dispersal and preferential accumulation of the fluvial terrigenous organic materials the simplified terrigenous som transport pathway to the central mud deposits of the ys was conceptually constructed based on the mixed sediments provenances hydrodynamic transport and depositional mechanism of the fine grained sediments in this region

the origin of n alkanes in santa monica basin surface sediment a model based on compound specific δ14c and δ13c data 14c and 13c values were measured for individual long chain n alkanes c24 33 from santa monica basin sediments the data were then simulated using a three component mixing model designed to represent the contributions of different sources the three selected end members were petroleum modern plant wax and shale derived alkanes the model was optimized to fit the data and to determine the fractional contribution of each component the results indicated that petroleum accounted for 12 of the alkanes in 0 2 5 cm sediment and 5 in 2 5 7 5 cm sediment modern plant waxes contributed 80 0 2 5 cm and 87 2 5 7 5 cm and the remaining 8 of each sample was attributed to the shale source the 14c concentration of the modern terrestrial end member was also determined from the model 14c values of 235 for the 0 2 5 cm post bomb horizon and 0 for the 2 5 7 5 cm pre bomb horizon indicate that plant leaf waxes have a continental residence time of decades in the southern california region

sources and distributions of branched and isoprenoid tetraether lipids on the amazon shelf and fan implications for the use of gdgt based proxies in marine sediments branched glycerol dialkyl glycerol tetraethers brgdgts in river fan sediments have been used successfully to reconstruct mean annual air temperature maat and soil ph of the congo river drainage basin however in a previous study of amazon deep sea fan sediments the reconstructed maats were ca 10 c colder than the actual maat of the amazon basin in this study we investigated this apparent offset by comparing the concentrations and distributions of brgdgts in amazon river suspended particulate matter spm and sediments to those in marine spm and surface sediments the riverine brgdgt input was evident from the elevated brgdgt concentrations in marine spm and surface sediments close to the river mouth the distributions of brgdgts in marine spm and sediments varied widely but generally showed a higher relative abundance of methylated and cyclic brgdgts than those in the river since this difference in brgdgt distribution was also found in intact polar lipid ipl derived brgdgts which were more recently produced the change in the marine brgdgt distribution was most likely due to marine in situ production consequently the maats calculated based on the methylation of branched tetraethers mbt and the cyclisation of branched tetraethers cbt were lower and the cbt derived ph values were higher than those of the amazon basin however spm and sediments from stations close to the river mouth still showed mbt cbt values that were similar to those of the river therefore we recommend caution when applying the mbt cbt proxy it should only be used in sediment cores that were under high river influence the influence of riverine derived isoprenoid gdgt isogdgt on the isogdgt based tex86 temperature proxy was also examined in marine spm and sediments an input of riverine isogdgts from the amazon river was apparent but its influence on the marine tex86 was minor since the tex86 of spm in the amazon river was similar to that in the marine spm and sediments

phosphorus distribution c n p ratios and δ13coc in arctic temperate and tropical coastal sediments tools for characterizing bulk sedimentary organic matter abstract onshore offshore trends in phosphorus p organic carbon oc and total nitrogen tn concentration p distribution elemental organic c n p ratios and stable carbon isotopic composition of oc 13 c oc of surficial sediments are presented from three river dominated coastal regimes the mackenzie river beaufort shelf in the canadian arctic the mississippi delta and louisiana shelf in the temperate gulf of mexico and the tropical amazon shelf these parameters measured in surficial sediments from the three sites are used to assess changes in the importance of terrestrial and marine organic matter sources to sediments as a function of distance from the locus of riverine discharge trends in elemental ratio data from the arctic transect and a portion of the gulf of mexico transects can be explained in terms of a two end member mixture of terrestrial and marine phytodetritus in the arctic transect covariation of organic c p ratios with 13 c oc is consistent with a two end member mixture of terrestrial and marine organic matter a similar relationship between c p ratios and 13 c oc is not evident in gulf of mexico or amazon shelf sediments at these sites the two end member model fails to explain the data adequately the most striking feature of the onshore offshore trends in elemental oc op and oc tn ratios is the occurrence of low ratios in sediments from deep water stations in the gulf of mexico and all stations on the amazon shelf resulting from p and n enrichments exceeding the redfield ratio for marine plankton three explanations are discussed to account for these low ratios 1 the dominance of refractory op and on compounds in the residuum of degraded organic matter 2 differential sorption of op and n compounds regardless of lability on the surfaces of the fine grained sediments characteristic of these sites and 3 a dominance of bacterial biomass or components derived from bacterial biomass elemental ratios and 13 c oc signatures indicate that differential sorption may be most important in the deep water gulf of mexico sites in contrast elemental ratios and 13 c oc on the amazon shelf are most consistent with a sedimentary organic matter pool dominated by bacterial biomass or derivative substances

sediment accumulation in a modern epicontinental shelf setting the yellow sea sediment accumulation in the yellow sea epicontinental shelf environment is investigated on 100 yr and 1000 yr time scales using 210pb and 14c geochronologies the distribution of modern 210pb accumulation rates in the yellow sea reveals that the loci of modern huanghe sediment accumulation are the topset 1 2 mm yr foreset 4 9 mm yr and proximal bottomset deposits 2 4 mm yr of the shandong subaqueous delta which extends south from the shandong peninsula 210pb rates in the distal bottomset deposits of the subaqueous delta in the central and southern yellow sea are generally low 0 3 0 9 mm yr a sediment budget demonstrates that between 9 15 of the annual huanghe discharge is accumulating in the yellow sea about two thirds of this sediment is accumulating in the topset foreset and proximal bottomset deposits of the shandong subaqueous delta with the remaining third accumulating as widespread distal bottomset deposits 14c age dates of subaqueous delta sediments indicate that the thick 40m clinoform structure formed predominantly between 6200 and 4060 yrs b p at rates approaching 20 mm yr observations in the yellow sea as well as on the amazon and ganges brahmaputra shelves demonstrate that subaqueous deltaic stratigraphy is the general rule where major rivers enter energetic shelves whether epicontinental or pericontinental the development of extensive bottomset deposits may be restricted to epicontinental shelf environments and may be diagnostic of sedimentation in this type of setting

assessment of the sources of sedimentary organic matter in the bohai sea and the northern yellow sea using biomarker proxies abstract to evaluate the applicability of source proxies and to assess the sources of sedimentary organic matter in the bohai sea bs and the northern yellow sea nys we analyzed total organic carbon toc total nitrogen tn 13c of toc n alkanes phytoplankton biomarkers and glycerol dialkyl glycerol tetraethers gdgts including branched gdgts brgdgts in 60 surface sediment samples covering the bs and the nys spatial distribution comparison and principal component analysis indicate that with the exception of brgdgts terrestrial biomarkers have different spatial distribution pattern from marine biomarkers suggesting that the sources control the distributions of these biomarkers in spite of hydrodynamic forcing significantly positive correlation r2 0 5 between toc normalized brgdgts content and toc normalized crenarchaeol content suggested in situ production of brgdgts in the bs and the nys the 13c values tmbr terrestrial and marine biomarker ratio c27 c29 c31 n alkanes c27 c29 c31 n alkanes brassicasterol dinosterol alkenones and bit branched isoprenoid tetratether index proxy indicated high terrestrial organic matter tom input near the huanghe river estuary while toc ton did not reveal similar distribution pattern quantitative estimates of tom using a binary model revealed much higher tom percentage from 13c avg 58 and tmbr avg 31 than from bit avg 7 4 our results suggest that owing to significant in situ production of brgdgts the bit is not a good proxy for indicating soil om contribution in marine sediments from the bs and the nys

investigating dynamic underground coal fires by means of numerical simulation summary uncontrolled burning or smoldering of coal seams otherwise known as coal fires represents a worldwide natural hazard efficient application of fire fighting strategies and prevention of mining hazards require that the temporal evolution of fire propagation can be sufficiently precise predicted a promising approach for the investigation of the temporal evolution is the numerical simulation of involved physical and chemical processes in the context of the sino german research initiative innovative technologies for detection extinction and prevention of coal fires in north china a numerical model has been developed for simulating underground coal fires at large scales the objective of such modelling is to investigate observables like the fire propagation rate with respect to the thermal and hydraulic parameters of adjacent rock in the model hydraulic thermal and chemical processes are accounted for with the last process complemented by laboratory experiments numerically one key challenge in modelling coal fires is to circumvent the small time steps resulting from the resolution of fast reaction kinetics at high temperatures in our model this problem is solved by means of an operator splitting approach in which transport and reactive processes of oxygen are independently calculated at high temperatures operatorsplitting has the decisive advantage of allowing the global time step to be chosen according to oxygen transport so that time consuming simulation through the calculation of fast reaction kinetics is avoided also in this model because oxygen distribution within a coal fire has been shown to remain constant over long periods an additional extrapolation algorithm for the coal concentration has been applied in this paper we demonstrate that the operator splitting approach is particularly suitable for investigating the influence of hydraulic parameters of adjacent rocks on coal fire propagation a study shows that dynamic propagation strongly depends on permeability variations for the assumed model no fire exists for permeabilities k 10 10 m 2 whereas the fire propagation velocity ranges between 340 m a 1 for k 10 8 m 2 and drops to lower than 3 m a 1 for k 5 10 10 m 2 additionally strong temperature variations are observed for the permeability range 5 10 10 m 2 k 10 8 m 2