china s yangtze estuary ii phosphorus and polycyclic aromatic hydrocarbons in tidal flat sediments abstract concentrations of phosphorus p and polycyclic aromatic hydrocarbons pahs were determined in tidal flat sediments from the yangtze estuary and hangzhou bay the amount of total p in surface sediments ranges from 18 0 to 31 4 mol g 1 along the southern coast the spatial and temporal distribution of p in tidal flats is closely related to geomorphological location and contaminant input especially in association with variations in hydrodynamic conditions speciation of p in sediments was extracted sequentially results show that calcium phases are dominant in the total p of tidal flat sediments which is similar to marine sediments the main diffusion of dissolved p is from overlying water to sediment in the coastal environment of the yangtze estuary two sediment cores from the baoshan bs and donghai dh sites were extracted for pah analysis the total concentration of pahs ranges from 0 061 to 7 618 g g 1 at the bs site and from 0 005 to 2 370 g g 1 at the dh site the distribution of total and individual pahs in the sediment shows a subsurface maximum following by decreased levels to the surface and with depth the pattern of pah abundance suggests that there has been significant petroleum contamination in the yangtze estuary a few individual pahs such as acenaphthalene and anthracene in surface samples of the two cores are in excess of current sediment quality criteria in the yangtze estuary the present study suggests that anthropogenic activities enhance contaminant inputs to the estuary

phosphorus cycling in sediments of the bohai and yellow seas using a box sampler surface and core sediment samples were collected from the bohai and yellow seas in 1998 1999 the sediments were sequentially extracted to determine six phosphorus fractions and non sequentially extracted for total p tp and inorganic p ip where the difference between tp and ip was assumed to be organic p op it was found that more than 70 of the total p is inorganic p the concentrations of phosphorus were high near the river mouth reflecting the influence from the huanghe and changjiang sediment loads the phosphorus levels in the bohai sea are higher than those in the yellow sea which is related to the sediment sources and distribution of chlorophyll a in these areas concentrations of tp in the bohai and yellow seas are comparable to the other worldwide coastal areas among the six forms of phosphorus phosphorus distribution ranges were 0 8 2 for loosely sorbed p 3 10 for iron bound inorganic p 4 19 for leachable organic p 3 15 for authigenic apatite 35 66 for detrital apatite and 14 36 for refractory organic p potentially bioavailable phosphorus accounts for a small amount of tp while phosphorus load associated with eroded soil may be larger than the anthropogenic load the regeneration of dissolved p from sediments is a slow process which could play a role in maintaining low phosphate levels in the seas most of the phosphorus was regenerated in a water column and almost all of the remaining phosphorus was buried in the sediments after its accumulation the high values of p burial efficiencies in the study areas were related to low benthic phosphate flux which is due to the high percent of detrital apatite that is not bioavailable and the high sediment accumulation rate

prehistoric heavy metal pollution on the continental shelf off hainan island south china sea from natural to anthropogenic impacts around 4 0 kyr bp human environment interactions across historical periods in china have been well reconstructed over the past decade however few studies have focused on southern china particularly hainan island

the structure biological activity and biogeochemistry of cryoconite aggregates upon an arctic valley glacier longyearbreen svalbard glacier surfaces support unique microbial food webs dominated by organic and inorganic debris called cryoconite observations from longyearbreen spitsbergen show how these aggregate particles can develop an internal structure following the cementation of mineral grains mostly quartz and dolomite by filamentous microorganisms measurements of carbon and dissolved o2 show that these microorganisms mostly cyanobacteria promote significant rates of photosynthesis average 17 gc g 1 d 1 which assist aggregate growth by increasing the biomass and producing glue like extracellular polymeric substances the primary production takes place not only upon the surface of the aggregates but also just beneath due to the translucence of the quartz particles however since total photosynthesis is matched by respiration average 19 gc g 1 d 1 primary production does not contribute directly to cryoconite accumulation upon the glacier surface the microorganisms therefore influence the surface albedo most by cementing dark particles and organic debris together rather than simply growing over it time lapse photographs show that cryoconite is likely to reside upon the glacier for years as a result of this aggregation these observations therefore show that a better understanding of the relationship between supraglacial debris and ablation upon glaciers requires an appreciation of the biological processes that take place during summer

measurement and parameterization of albedo variations at haut glacier d arolla switzerland spatial and temporal variations of surface albedo on haut glacier d arolla switzerland during the 1993 and 1994 ablation seasons are described correlation and regression analyses are used to explain the albedo variations in terms of independent meteorological and surface property variables parameterizations are developed which allow estimation of albedo variation in surface energy balance models snow albedo is best estimated from accumulated daily maximum temperatures since snowfall on deep snow 0 5 cm w e depth a logarithmic function is used while on shallow snow 0 5 cm w e depth an exponential function is used to enable the albedo to decay to the underlying ice or debris albedo the transition from deep to shallow snow is calculated as a function of decreasing snow depth combined r 2 0 65 this new parameterization performs better than earlier schemes because accumulated daily maximum temperatures since snowfall correlate strongly with snow grain size and impurity concentration the main physical controls on snow albedo ice albedo may be parameterized by its relationship to elevation r 2 0 28 but this approach results in only a small improvement over the assumption of a constant mean ice albedo

spatial variability and the controlling mechanisms of surface sediments from nam co central tibetan plateau china abstract sixty six surface sediments were retrieved from nam co central tibetan plateau to evaluate the spatial variability of their distributions and controls across the entire lake grain size distribution total carbon total nitrogen total sulfur 210 pb and 137 cs activities and carbon and oxygen isotopes of carbonate of the bulk sediments were analyzed and the correlations among these variables as well as water depth were calculated the results showed distinct spatial variability for all variables the grain size distribution provides adequate information to reflect water energy levels within the lake based on these factors the accumulation zone of nam co was distinguished from the erosional and transportation zones the results indicate that the deep area 80 m of the central main basin and the centre of the eastern small basin serve as the accumulation zones in nam co water depth is the most important factor influencing the distribution of the surface sediments because all variables show different distribution patterns in shallow and deep areas additionally river input sediment focusing grain size effects and heterogeneous physicochemical features of the lake water as well as possible currents within the lake also play different roles that affect surface sediment characteristics water depth noticeably affects grain size and the 13 c and 18 o values of carbonate sediment implying that these proxies could be used as indicators of lake level change these findings are of significance for palaeoenvironmental interpretations when using these proxies

evolution of cryoconite holes and their contribution to meltwater runoff from glaciers in the mcmurdo dry valleys antarctica cryoconite holes are water filled holes in the surface of a glacier caused by enhanced ice melt around trapped sediment measurements on the ablation zones of four glaciers intaylorvalley antarctica show that cryoconite holes cover about 4 6 of the ice surface they typically vary in diameter from 5 to 145 cm with depths ranging from 4 to 56 cm in some cases huge holes form with 5 m depths and 30 m diameters un like cryoconite holes elsewhere these have ice lids up to 36 cm thick and melt from within each spring about one half of the holes are connected to the near surface hydrologic system and the remainder are isolated the duration of isolation estimated from the chlor ide accumulation in hole waters commonly shows ages of several years with one hole of 10 years the cryoconite holes in the mcmurdo dryvalleys create a near surface hydro logic system tens of cm below the ice surface the glacier surface itself is generally frozen and dry comparison of water levels between holes a few meters apart shows independent cycles of water storage and release most likely local freeze thaw effects control water passage and therefore temporary storage rough calculations indicate that the holes gen erate at least 13 of the observed runoff on the one glacier measured this hydrologic system represents the transition between a melting ice cover with supraglacial streams and one entirely frozen and absent of water abstract cryoconite holes are water filled holes in the surface of a glacier caused by enhanced ice melt around trapped sediment measurements on the ablation zones of four glaciers intaylorvalley antarctica show that cryoconite holes cover about 4 6 of the ice surface they typically vary in diameter from 5 to 145 cm with depths ranging from 4 to 56 cm in some cases huge holes form with 5 m depths and 30 m diameters un like cryoconite holes elsewhere these have ice lids up to 36 cm thick and melt from within each spring about one half of the holes are connected to the near surface hydrologic system and the remainder are isolated the duration of isolation estimated from the chlor ide accumulation in hole waters commonly shows ages of several years with one hole of 10 years the cryoconite holes in the mcmurdo dryvalleys create a near surface hydro logic system tens of cm below the ice surface the glacier surface itself is generally frozen and dry comparison of water levels between holes a few meters apart shows independent cycles of water storage and release most likely local freeze thaw effects control water passage and therefore temporary storage rough calculations indicate that the holes gen erate at least 13 of the observed runoff on the one glacier measured this hydrologic system represents the transition between a melting ice cover with supraglacial streams and one entirely frozen and absent of water

grain size effect on multi element concentrations in sediments from the intertidal flats of bohai bay china abstract in the intertidal flats of bohai bay china the spatial distribution of the grain size of sediments becomes coarser from landward to seaward to study the grain size effect on multi element concentrations in sediments samples along the coastline and 3 horizontal cross sections were collected from the intertidal flats of bohai bay china in 1998 total concentrations of 49 elements including alkali alkaline earth trace metal rare and rare earth elements were measured by icp aes icp ms and inaa the results show that sediment texture plays a controlling role on the concentrations and their spatial distribution principal component analysis and cluster analysis were carried out based on the grain sizes of the sediments and the samples were classified into 3 groups mud silt mud and silt significant differences among the element concentrations in the 3 groups were observed and the concentrations of the elements in each group are reported in this study most of the elements have their highest concentrations in the fine grained mud samples in comparison with the silt and silt mud samples with clay minerals possibly playing an important role in contrast concentrations of ba sr hf and zr are elevated in the coarse silt samples ba and sr may reside in feldspars while zr and hf are present in zircons landward to seaward spatial variation of element concentrations in the sediments is observed which is in line with the spatial distribution of the grain size and is related to the seawater hydrological dynamics in the intertidal flats

abrupt change of sediment records in the southern south china sea during the last glacial period and its environment significance abstract chemical compositions of sediments at core ns07 25 6 39 945 n 113 32 936 e water depth 2006 m are analyzed to discuss abrupt change of sediment records in the southern south china sea scs during the last glacial period and its environmental implications major and trace elements experienced three significant changes which occurred at 31 9 26 1 and 18 5 ka bp respectively at 31 9 ka bp when sea surface temperature remained relatively low terrigenous sediment flux increased but biogenic activities weakened greatly at 26 1 ka bp both terrigenous sediment flux and biogenic fractions number were steady however some elemental ratios changed noticeably at that time before 26 1 ka bp core sediments with low nb ta but high zr hf ratios were mainly derived from the paleo mekong and or molengraaff rivers exposed on the sunda shelf at that time after 26 1 ka bp sediments with high nb ta but low zr hf ratios probably relate to strengthened impact of deep water current since 18 5 ka bp sea level ascended rapidly from 110 m below the present terrigenous sediment flux decreased and biogenic activities strengthened continuously probably related with the east asian monsoon evolution

rare earth elements in the surface sediments of the yarlung tsangbo upper brahmaputra river sediments southern tibetan plateau abstract the yarlung tsangbo yt is the tibetan portion of the brahmaputra river it transports a large amount of sediment annually to the indo gangetic plain and thus contributes significantly to the quaternary evolution of the plain eighteen surface sediment samples were collected from the yt and the compositions of rare earth elements rees were analyzed for the bulk sediments

rare earth element geochemistry and nd isotope composition of stream sediments south han river drainage basin korea abstract chemical analyses of parent rock soil and stream sediments were done to determine to what extent the river sediments retain the geochemical signature of the parent rocks the study area consists mainly of mesozoic biotite granite and precambrian biotite gneiss located in the central korean peninsula the drainage system consists of tributaries of the south han river such as bokhacheon shinduncheon and yanghwacheon stream sediments were collected every march during 2004 2006 the sediments collected were divided into coarse gravel to sand size and fine silt to clay size more than 90 is coarse sediment the major element composition of the coarse and fine sediments are not identical to the weathering trend of granite however molar proportions of al2o3 cao na2o and k2o in the sediments show that they were derived from granitoids rather than from biotite gneiss the total fe2o3 cao mgo na2o and mno contents and ree concentrations of the fine sediments are higher than those of the coarse sediments in a weathering profile from the granite and gneiss area there was no change of ree distribution pattern from the fresh rock to soil compared to biotite granite normalized ree pattern for the sediment both coarse and fine sediments have relatively flattened ree patterns and all the coarse sediment have positive eu anomalies whereas in the fine sediments negative eu anomalies prevail nd isotopic composition of the sediments is similar to that of the biotite granite rather than the biotite gneiss stream sediments in the icheon area were derived from the granite nd isotope geochemistry as well as ree geochemistry is useful tool for tracing the provenance of the river sediments

pre columbian agriculture in the bolivian lowlands construction history and management of raised fields in bermeo abstract recent archaeological research suggests that some parts of the amazon basin were significantly modified by pre columbian populations one of the most impressive examples of such transformations is the raised fields of south western amazonia in the llanos de moxos in the bolivian lowlands despite a growing interest in raised field agriculture due to the important role it seems to have played in the development of pre columbian complex societies very few field based investigations have been performed in the amazon basin as a result there is limited knowledge of how these fields were constructed managed and within which time frame they were in use this study provides a new interpretation of how pre columbian raised fields were managed and a chronological sequence of their utilisation and eventual abandonment fieldwork was carried out in the indigenous community of bermeo in the vicinity of san ignacio de moxos where some of the best preserved fields in the llanos moxos are found magnetic susceptibility and the geochemistry of the sediments combined with radiocarbon and optically stimulated luminescence dating show that the raised fields were in intermittent use since as early as ad 570 770 the original surface on which the fields were built and distinct periods of construction and use have been identified the data suggests that raised fields were built during a few separate construction events probably linked to periods of more frequent and severe floods the study challenges the most widely accepted theory that suggests that pre columbians were able to cultivate these fields on a continuous basis by transferring nutrient rich sediments from the canals to the fields we conclude that pre columbians built raised fields to overcome periods of increased flooding with the main objective of improving drainage

controls on phosphorus concentration and accumulation in oceanic sediments understanding phosphorus p sedimentation in the ocean is important both for quantifying outputs in the marine phosphorus cycle and for determining the controls on phosphogenesis the authigenic formation of carbonate fluorapatite and phosphorite deposition large accumulations of p rich sediments on continental margins in this study i have compiled literature data on sedimentary p concentrations and sedimentation rates from continental margins phosphogenic continental margins and open ocean environments i have also calculated p accumulation rates the product of p concentration sediment density and sedimentation rate in these settings sedimentary p concentrations exhibit a similar range in a wide variety of oceanic environments and sedimentation rate conditions for example p concentrations in continental margin sediments range from 8 to 108 mol p g 1 with sedimentation rates from 80 to 8 000 m my 1 in open ocean sediments the p concentration range is similar 7 307 mol p g 1 even though sedimentation rates are generally about 100 times lower 2 50 m my 1 the exception to this are phosphogenic environments where p concentrations are exceptionally high 580 3 700 mol p g 1 while sedimentation rates are relatively low 20 310 m my 1 phosphorus accumulation rates appear to be controlled by sedimentation rate in ocean sediments although p concentrations generally exhibit similar ranges the large difference in sedimentation rates between various environments results in p accumulation rates that are several orders of magnitude higher in continental margins 90 8 000 mol p cm 2 kyr 1 compared to open ocean sediments 2 75 mol p cm 2 kyr 1 in the case of phosphogenic environments low sedimentation rates result in p accumulation rates 80 6 300 mol p cm 2 kyr 1 that are surprisingly similar to those of non phosphogenic continental margin sediments

heavy metal concentrations in sultana cultivation soils and sultana raisins from manisa turkey this paper describes the concentrations of heavy metals in soils and in raisins sultanas cultivated upon the gediz plain manisa western turkey which is cut by major roads from izmir to istanbul and izmir to ankara a total of 212 samples of surface soil and 82 raisin samples were analysed soil samples have nearly same mineralogy quartz calcite magnetite pseudo rutile and clay minerals dolomite is seen especially in areas close to neogene sediments clay minerals are mainly mica illite muscovite chlorite kaolinite smectite and mixed layers sm il the concentrations of 21 elements ba ni mo cu pb zn co mn as u sr cd sb bi cr b w hg sn li and organic c were determined in the surface soils the degree of element enrichment in soil can be measured in many ways the most common of which are the geoaccumulation index igeo enrichment factor and the pollution index arsenic and sb showed the highest igeo values corresponding to igeo classes 3 4 hence the area is characterised as being heavily contaminated to polluted by as and sb arsenic contamination has been reported from all over world arsenic related pollutants enter the groundwater system by gradually moving with the flow of groundwater from rains and irrigation gediz plain forms the main groundwater supply of izmir city the enrichment factor efarsenic of the analysed soil samples is around 76 which corresponds to extremely high enrichment the concentrations of 33 elements al sb as ba be bi b cd ca cr co cu fe pb li mg mn hg mo ni k se ag na sr ta th sn ti u v zn and zr were determined in the raisin samples the pb and cd contents of raisins are of great concern due to their toxicity pb contents ranged between 0 05 and 0 46 mg kg 1 and average cd content was 0 04 mg kg 1 only one sample contained high level of cd 0 23 mg kg 1 after cleaning the raisins the heavy metal concentrations were low as in the european community ec regulation no 466 2001 for allowable levels of pb 0 2 mg kg 1 and cd 0 05 mg kg 1

long term cooling drying record of north china since the middle pleistocene from geochemical evidence of a 150 m deep drill core beijing plain china the quaternary strata in north china primarily consist of fluvial sediments which react strongly to east asian monsoon circulation however the records of the quaternary climate change history in terms of these fluvial sedimentations were limited which impeded understanding the east asian monsoon evolution in north china thus a 150 m deep drill core was collected from changping in the beijing plain to reconstruct the quaternary palaeoenvironmental changes the core was chronologically well constrained using palaeomagnetic and thermoluminescence dating the magnetostratigraphic result indicated that the brunhes matuyama boundary is at 134 2 m 0 78 ma and the age at the bottom of the core is 1 07 ma the thermoluminescence tl dating of the upper sand at similar to 2 m was 10 4 ka the chemical weathering history since the middle pleistocene in beijing plain was reconstructed by using geochemical proxies including selected major element pairs chemical index of alteration and al2o3 cao na2o k2o diagrams the cia value of the changping core ranged from 50 3 to 69 4 average 59 2 which indicated that the sediment has experienced incipient to intermediate chemical weathering during the middle pleistocene the result of a cn k figure shows a high plagioclase to k feldspar ratio in the source which would be indicative of a granodiorite gd source from jundu mountains north of the beijing plain all the geochemical results revealed a long term gradual decrease of weathering since the middle pleistocene which implied a long term increasing aridification cooling in the beijing plain c 2014 elsevier ltd and inqua all rights reserved

facies discrimination in a mixed fluvio eolian setting using elemental whole rock geochemistry applications for reservoir characterization abstract fluvio eolian successions are generally characterized by a high degree of complexity and internal heterogeneity quantifying the rapid facies changes in time and space is a major challenge to characterization of hydrocarbon reservoirs we present a method for facies discrimination in fluvio eolian successions the method presented here is developed on the modern fluvio eolian sediments from the skeleton coast dune field namibia the examined sediments comprise eight different facies types eolian dune sands interdune fluvial channel sands intraerg mass flow deposits intraerg hyperconcentrated flow deposits fluvial channel sands fluvial mud lacustrine heterolithic sand and lacustrine heterolithic mud the contrasting provenance of the fluvial and eolian sediments results in a distinct source fingerprint which can be discriminated using elemental whole rock geochemistry a multivariate statistical technique performed on the geochemical data has enabled discrimination of seven of the eight facies types furthermore the facies discrimination method allowed a quantitative estimate of the degree of fluvial reworking of eolian sand the skeleton coast dune field was chosen as a test area for geochemical facies discrimination because of its remarkable difference between the immature fluvial source and the mature quartz rich eolian source we hope that the method presented here can be applied to subsurface data from geological settings with the same difference in fluvial and eolian sources it is furthermore hoped that the method can be used in more complex sedimentological settings

geocatalytic reactions in formation and maturation of petroleum theory and experiments suggest that catalytic reactions are involved in petroleum formation this suggestion is not new but has never gained wide acceptance a model chemical system illustrates that acid catalyzed reactions can explain several key transformations in the generation and maturation of oil it also is shown that such reactions should occur under geologically reasonable conditions and that naturally occurring active catalysts exist in many sediments catalytic principles indicate that the nature and amount of these catalysts in sediments can importantly control the fate of organic substances therein it is suggested that under a given time temperature history organic matter in a sediment may or may not generate petroleum depending on the concentration and a tivity of the geocatalysts stated another way sediments differ in the time temperature histories needed to generate petroleum

revisit of rare earth element fractionation during chemical weathering and river sediment transport although rare earth element ree has been widely applied for provenance study and paleoenvironmental reconstruction its mobility and fractionation during earth surface processes from weathering to sediment deposition remain more clarification we investigated the ree fractionations during chemical weathering and river sediment transport based on the systematic observations from a granodiorite weathering profile and mulanxi river sediments in southeast china two chemical phases leachates and residues were separated by 1 n hcl leaching and the leachates account for 20 70 of the bulk ree concentration rees in the weathering profile have been mobilized and fractionated to different extents during chemical weathering and pedogenesis remarkable cerium anomalies ce ce 0 1 10 6 occur during weathering as a result of co precipitation with mn hydro oxides in the profile while poor or no ce anomalies in the river sediments were observed this contrasting feature sheds new light on the indication of ce anomaly for redox change the hydraulic sorting induced mineral redistribution can further homogenize the weathering and pedogenic alterations and thus weaken the ree fractionations in river sediments the mineral assemblage is the ultimate control on ree composition and the mn fe hydro oxides and secondary phosphate minerals are the main hosts of acid leachable rees while the clay minerals could be important reservoirs for residual rees we thus suggest that the widely used ree proxies such as lree hree ucc ratio in the residues is reliable for the indication of sediment provenance while the ratio in the leachates can indicate the total weathering process to some extent this article is protected by copyright all rights reserved

sulphur organic carbon and iron relationships in estuarine and freshwater sediments effects of sedimentation rate abstract concentrations of s organic c and fe were investigated in profiles of sediments from two estuarine systems in the sw of western australia in marine affected sediments inorganic s dominates total s and concentrations of total s correlate with fe and not with organic c in freshwater sediments organic s dominates total s and concentrations of total s correlate with organic c and not with fe molar fe s ratios in the estuarine sediments decrease with increasing salinity and approach unity for marine conditions net accumulation rates of s in sediments were estimated with a numerical computer model calibrated with published data on profiles of marine sediments for diffusion of so2 4 sedimentation rates and distributions of s measured depth integrated reduction rates of so2 4 in the marine affected estuarine sediments approach those obtained for fe limited marine conditions at similar rates of sedimentation measured concentrations of inorganic s in anoxic freshwater sediments fit a numerically calculated relationship between inorganic s and sedimentation rate

late quaternary river terraces in the central mountain range of taiwan a study of cover sediments across a terrace section along the tachia river abstract the existence of fluvial terraces in the high mountains of taiwan has been known for a long time already but these terraces have not yet been studied in detail this paper studies cover sediments across a terrace section in the central mountain range located at the midstream reaches of the tachia river at an elevation of 1430 m asl sediments were dated by means of optically stimulated luminescence and radiocarbon dating yielding robust ages between 54 8 7 0 ka and 0 42 0 09 cal ka bp these dates are in good agreement with ages known for the laterite terraces lt in the mountain foreland deeply weathered reddish soils comparable to those in the mountain forelands are absent hence in stratigraphic terms the terraces in the high mountains cannot be correlated with those in the mountain foreland cover sediments comprise eolian sand and silt and various colluvial layers eolian sediments provide paleoenvironmental evidence of a relatively dry phase in early mis 3 that coincides with the maximum extent of the glaciations in the hsueh shan mountain area widespread colluvial sediments indicate a high frequency of mass movements around 38 5 ka a period of time known to correlate with dominantly wet conditions in the last 1000 years wildfire appears as a possible trigger of mass movements the geochronological data indicate a local bedrock strath incision rate of 0 8 0 1 mm y 1 a value that appears to be in agreement with the local decadal scale erosion rate

early middle miocene tectonic uplift of the northwestern part of the qinghai tibetan plateau evidenced by geochemical and mineralogical records in the western tarim basin the tarim basin in western china has been receiving continuous marine to lacustrine deposits during the cenozoic as a foreland basin of the qinghai tibetan plateau qtp clay mineralogy and geochemical proxy data from these sedimentary archives can shed light on climate and tectonic trends here we report on an abrupt mineralogical and weathering shift at 17 ma 1 myr in the miocene qimugan section in the northwestern part of the qinghai tibetan plateau the rapid shift involves decreasing trends of chemical weathering indices rb sr and ba sr ratios and of minor and immobile elements with respect to upper crust composition as well as increasing trends of na al and na ti ratios smectite chlorite and calcite contents we ascribe these trends to changing source rocks due to uplift of the northern part of the qtp leading to exposures of younger intrusive bodies and older gneisses schists and carbonate rich rocks these uplifts potentially caused regional aridification reducing chemical weathering the dating is indirect via magnetostratigraphically dated ostracod biostratigraphy and detrital zircon chronology and currently not good enough to compare the shift accurately in time with the onset of the global middle miocene climate optimum mmco at 16 5 ma nevertheless regional tectonics seem to have dominated over global climate as the warmer mmco is expected to have increased weathering indices and decreased na al and na ti rather than the observed reverse trends

sedimentary iron phosphorus cycling under contrasting redox conditions in a eutrophic estuary abstract phosphorus p is often a limiting nutrient within freshwater and estuarine systems thus excess inputs of p from anthropogenic activities dominantly agriculture can induce eutrophication in receiving water bodies the sequestration of p within estuarine sediments is controlled by sorption and precipitation processes which are impacted by local redox conditions and burial environment despite the global spread of oxygen depletion in coastal marine systems p burial under reducing conditions remains poorly understood we investigated p cycling in relation to iron fe redox chemistry in sediments from the eutrophic peel harvey estuary in western australia using a combination of porewater analysis sequential chemical p extractions synchrotron based micro scale x ray fluorescence mapping and fe k edge x ray absorption spectroscopy and po43 sorption experiments the sediments represented redox regimes varying from strongly reducing organic rich sediments with little or no reactive fe iii oxyhydr oxides to oxygenated sediments that were enriched in reactive fe iii phases organic p and fe associated p were the main p burial phases and the latter was quantitatively important even in sediments with an overall strongly reducing character we attribute this to adsorption of p onto micro scale fe iii oxyhydroxide enrichments and or fe bearing clay minerals the organic rich sediments showed a strong decline in p contents with depth p was released from organic matter and fe phases but apatite precipitation was apparently inhibited in these sediments despite greater and stronger po43 sorption capacity the oxic sediments contained relatively little p due to a lack of the primary p source in marine sediments organic matter our results provide detailed insight into p burial in dynamic estuarine sediments and show that micro scale spectroscopic analyses greatly advance our understanding of p sequestration processes

the mass area relationship within cryoconite holes and its implications for primary production cook j hodson a telling j anesio a irvine fynn t bellas c 2010 the mass area relationship within cryoconite holes and its implications for primary production annals of glaciology 51 56 106 110

the cryoconite ecosystem on the greenland ice sheet this paper presents an assessment of biological activity associated with ice surface debris cryoconite at the ice sheet scale estimates of the mass distribution of cryoconite over the greenland ice sheet gis and the biological activity associated with it are presented and then coupled with a surface mass balance model to estimate total carbon fluxes due to respiration and photosynthesis we find an average loading of 66 g m 2 at kangerlussuaq southwest greenland which compares well with recent estimates from kronprins christians land 17 440 g m 2 boggild and others 2010 in northeast greenland we also report a significant microbial biomass in cryoconite at both these places 10 3 10 4 cells mg 1 and carbon fluxes of the order of 1 3 m mcg 1 d 1 for both respiration and photosynthesis the modelling indicates that total respiration and photosynthesis fluxes are likely to be 10 1 10 2 gg c a 1 and thus far from trivial however estimation of the net ecosystem impact across the entire ice sheet on atmospheric co2 concentrations is problematic because photosynthesis rates were almost certainly low during our field campaign therefore like its water balance the carbon balance of the gis is now known to be important but its accurate quantification will remain elusive until more data are forthcoming

geochemical correlation in deltaic successions a reality check whole rock geochemical analysis can aid the stratigraphic correlation of faunally barren successions compared to petrographic techniques or heavy mineral separations such analysis is quick and objective yet rarely has the reliability of the method been tested against unequivocal correlations we have applied it to the kenilworth member of the upper cretaceous blackhawk formation a well exposed and easily correlated 100 m thick unit in the deltaic successions of the book cliffs utah united states this is the first evaluation of geochemical analysis as an aid to sequence stratigraphic interpretation at the parasequence scale from the geochemistry alone it is not possible with statistical confidence to separate individual parasequences or systems tracts nor the fluvial incised valley from the marine shoreface units the magnitude of geochemical variation in a single sandstone bed over a 30 m lateral traverse is as great as vertically through an entire parasequence y nb rb and ti abundances are inversely correlated with grain size thus geochemical signatures follow sedimentological trends and distal parts of a parasequence appear distinct from proximal parts y ratios compensate for this grain size effect but introduce confusing distortions for elements such as zr that are not correlated with grain size contrary to some predictions zr is as common in the finest grained units as the coarsest and sr is not correlated with ca in some sections sr is also inversely correlated to grain size and cannot be used as an indicator for cement abundance

evaluating trace elements as paleoclimate indicators multivariate statistical analysis of late mississippian pennington formation paleosols kentucky u s a abstract the temporal and spatial distributions of trace elements in paleosols in relation to soil forming processes and climate have received little attention primarily due to their generally low concentrations 100 ppm and a fundamental lack of knowledge of their behavior in soil systems trace element concentrations of pennington formation paleosols spanning an 8 ma interval in the late mississippian chesterian were analyzed using linear and multivariate statistics of whole rock elemental data linear statistics of the elemental data set show that ti zr nb cs la hf ta w ce and th have the highest correlation through time with r values 0 75 nb served as the proxy trace element for comparison temporal trends in nb closely match trends in lessivage clay formation and accumulation by feldspar weathering mean annual precipitation map and chemical weathering map effectively controls soil hydrology and the accumulation of organic matter and clay map in conjunction with chemical we

the marine phosphorus cycle phosphorus introduced to the ocean must ultimately be removed if a steady state is to be maintained over geologic time aeolian input is insignificant and there is evidently no hydrothermal contribution rivers dominate p input to the ocean the fluvial p flux is poorly quantified due to the interactions of two factors 1 man s influence on river nutrient fluxes and 2 inherent complexities in understanding the biological and inorganic associations of p in estuarine and coastal waters our best estimate of the natural or pre man p input flux is about 10 x 10 sup 9 moles p cm sup 2 ocean surface year of the identified flux of phosphorus to the sediments about 90 percent is in the form of biogenic debris or its regeneration products the burial of phosphatic fish debris is negligible p removal by direct reaction of phosphate in seawater with sea floor basalts during mid ocean ridge hydrothermal circulation is insignificant p removal by processes such as sorption on clay surfaces or formation of authigenic fe and al phosphate phases is presently unquantified and remains a serious uncertainty in the phosphorus cycle the identified sources and sinks approximately balance yielding a residence time for p in the oceans of about 10 sup 5 yrs

geochemistry and provenance of the altendorf feldspathic sandstone in the middle bunter of the thuringian basin germany an integrated mineralogical and geochemical study of the altendorf feldspathic sandstone in the middle bunter of the thuringian basin germany was carried out to obtain more information on its provenance sedimentological history and geochemistry the fine to coarse grained sandstone has an average composition of 66 63 71 quartz 30 27 35 feldspar and a fine grained illitic matrix the heavy mineral assemblage consists mainly of tourmaline zircon rutile apatite and opaque fe ti minerals it is inferred that this terrigenous material was laid down at the margin of the bunter basin high abundances of igneous quartz grains determined by cathodoluminescence cl the lack of metamorphic heavy minerals as well as alkali feldspar with an average k2o na2o ratio of 14 9 point to material of mostly granitic origin regional geologic and paleogeographic observations suggest that granites of the older and younger intrusive complex of the western erzgebirge are possible source rocks of the feldspathic sandstone the geochemical signature of the alkali feldspar k2o na2o ratio bao content points to the bergen and kirchberg granites as possible parent rocks comparing the mineralogical and geochemical data of the presumed source granites with those of the altendorf sandstone provides information on the sedimentation processes weathering fluvial transport and sedimentation under arid climatic conditions have caused complete decomposition and removal of plagioclase and biotite lowered the bulk ree content and led to the development of a positive eu anomaly the immobile trace elements e g ta th zr sc co ti are best suited for provenance determination because of their relatively low mobility during sedimentary processes elemental ratios such as la sc th sc co th and th ta have inherited the signature of the parent rocks and thus may be particularly useful for provenance studies to evaluate the control of specific minerals and grain size fractions on the distribution of trace elements in the sandstone separated fractions of quartz feldspar the 20 m fraction and heavy minerals were additionally analyzed the concentration densities elemental concentration in the fraction fraction weight reveal that with exception of hf the influence of the heavy mineral fraction on the whole rock geochemistry is insignificant although this fraction generally plays the most important role as carrier of trace elements quartz feldspar and the 20 m fraction have similar concentration densities between 20 and 40 for the ree with exception of eu which is mainly hosted in feldspar strong positive eu anomaly the influence of the 20 m fraction on the distribution of the ree and the elements u th sc ta strongly depends on the abundance of this fraction in the sediment alkali feldspar contains most of the ba sr rb and cs in the samples concentration densities of up to 97 thus differences in the abundances of these elements in whole rock samples can be related to changes in the mineralogical composition quartz feldspar ratio of the sediment

paleoenvironmental changes in the east japan sea during the last 48 ka indications from high resolution x ray fluorescence core scanning paleoceanographic changes in the east japan sea during the late quaternary based on high resolution elemental variations particularly correlations between dark light laminations and millennial scale climatic changes have remained poorly understood because of the lack of the high resolution proxies the recent application of micro x ray fluorescence xrf core scanning provides the potential for high resolution study on the laminations deposited in the east japan sea in this study we present a geochemical study by using micro xrf core scanning on a 730 cm core recovered from the east japan sea elemental variations and factor analysis indicate that the sedimentary environment changed from anoxic to suboxic conditions from marine isotope stage mis 2 3 to mis 1 which is induced by increased contribution of high salinity sea water from the open ocean due to the rising sea level the dark and light laminations during mis 2 3 were correlated with dansgaard oeschger cycles and summer monsoon proxy with dark colored sediments related to higher terrigenous concentration corresponding to warm moist and enhanced summer monsoon period during the interstadial period more terrigenous sediments were transported to the east japan sea via the strengthened fluvial discharge from the surrounding continents caused by enhanced monsoon rainfall thus the development of the east asian summer monsoon and consequent variations in fluvial discharge would have significantly affected the paleoceanographic conditions in the east japan sea during the mis 2 3 sea level lowstand copyright 2012 john wiley sons ltd

carbon burial rates in sediments and a carbon mass balance for the herbert river region of the great barrier reef continental shelf north queensland australia the largest century scale carbon reservoir in the herbert river sector of the great barrier reef continental shelf is carbonate carbon this carbonate carbon is produced by corals coralline algae and other benthic organisms and is stored on less than 13 of the area of the shelf maximum organic carbon burial rates 1 28 mol m 2 yr 1 occur within a wind protected 20 m water depth embayment 1 area of the shelf where the highest bulk sedimentation rates 1 12 kg m 2 yr 1 were determined from 210pb and137 cs profiles in 1 4 m cores sediment organic carbon oc and carbonate carbon cc accumulation rates are very low in the great barrier reef lagoon shelf and slope where most annual productivity 8 15 mol oc m 2 yr 1 is decomposed by algal and microbial respiration a carbon mass balance indicated that approximately 1 of combined river and marine organic carbon production was preserved in across shelf sedimentation but 3 of river and mangrove organic carbon input was preserved in this small wind protected embayment an across shelf carbon mass balance model predicted average shelf organic matter respiration correctly and the ratio of organic carbon fixation to respiration corrected for burial losses was 1 06

the ablation zone in northeast greenland ice types albedos and impurities ice types albedos and impurity content are characterized for the ablation zone of the greenland ice sheet in kronprinz christians land 80 n 24 w along this ice margin the width of the ablation zone is only about 8 km the emergence and melting of old ice in the ablation zone creates a surface layer of dust that was originally deposited with snowfall high on the ice sheet this debris cover is augmented by locally derived wind blown sediment subsequently the surface dust particles often aggregate together to form centimetre scale clumps that melt into the ice creating cryoconite holes the debris in the cryoconite holes becomes hidden from sunlight raising the area averaged albedo relative to surfaces with uniform debris cover spectral and broadband albedos were obtained for snow ice hummocks debris covered ice cryoconite studded ice and barren tundra surfaces broadband ice albedos varied from 0 2 for ice with heavy loading of uniform debris to 0 6 for ice hummocks with cryoconite holes the cryoconite material itself has albedo 0 1 when wet areal distribution of the major surface types was estimated visually from a transect video as a function of distance from the ice edge 330 m a s l ablation rates were measured along a transect from the ice margin to the slush zone 8 km from the margin 550 m a s l traversing both pleistocene and holocene ice ablation rates in early august averaged 2 cm d 1 impurity concentrations were typically 4 3 mg l 1 in the subsurface ice surface concentrations were about 16 g m 2 on surfaces with low impurity loading and heavily loaded surfaces had concentrations as high as 1 4 kg m 2 the mineralogical composition of the cryoconite material is comparable with that of the surrounding soils and with dust on a snowdrift in front of the ice margin implying that much of the material is derived from local sources a fine mode clay is present in the oldest ice but not in the nearby soil suggesting that its origin is from wind deposition during pleistocene glaciation

phosphate regeneration from sediments of the peru continental margin by dissolution of fish debris generally oxidative regeneration of phosphate from anoxic sediments is by microbially mediated sulfate reduction processes stoichiometric modelling of such reactions takes into consideration varying proportions of decomposable organically bound p to account for the ratios among nutrients in depth concentration profiles of near surface sediments new results of interstitial water composition from sediments underlying the water masses influenced by coastal upwelling of the eastern boundary current system off peru indicate that dissolution of phosphatic fish debris represents a mechanism for remineralization of phosphate comparable to or larger in magnitude than that by oxidative regeneration of organically bound p dissolved interstitial phosphate from fish debris is revealed by an excess amount of phosphate over that predicted from a simple stoichiometric oxidative regeneration model and by anomalously high dissolved interstitial fluoride concentrations phosphate flux estimates based on diffusion from the sediment suggest that this mechanism may generate up to 10 of the nutrient pool in the waters of the peru undercurrent partitioning of p among the two sources reveals further that fish debris phosphate is about four times more important than organically bound p in nutrient generation from sediments of the peru continental margin not only does this mechanism of regeneration affect the nutrient cycling but may also control widespread phosphorite formation in this area

confidence limits on kinetic models of primary cracking and implications for the modelling of hydrocarbon generation abstract kinetic models of primary cracking for use in hydrocarbon modelling are obtained through empirical calibration against laboratory measurements this paper utilizes least squares variance analysis to evaluate the uncertainty in the calibrated kinetic parameters and discusses some consequences for the prediction of hydrocarbon generation it is substantiated that the sensitivity of the average kinetic parameters e a and log e a to micropyrolysis errors can be parameterized by errors in pyrolysis tmax the absolute and relative errors in tmax are modelled by normal gaussian random variables and the variance analysis yields the joint normal probability density distribution of variability in e a and log e a it is found that tmax errors reduce the ability to resolve independently the values of e a and log e a the estimation errors are highly positively correlated and repeated measurements on identical kerogens will produce values of e a and log e a which tend to fall close to and along the line log e a e a irt p constant where tp is an average pyrolysis temperature this correlation is consistent with observations and hence it is suggested that it is mainly an artifact which originates in the experimental errors of laboratory pyrolysis when values of e a and log e a are confined to the region of the confidence ellipsoid the pyrolysis data are satisfied within their error bounds however the variability in predictions of hydrocarbon generation may be large depending on the particular geological temperature history the uncertainties in the depth to the oil window may be several hundreds of metres and the timing of peak hydrocarbon generation rate may vary considerably the inclusion of basin geochemical data in the calibration drastically reduces the ambiguity in e a and log e a and emphasizes the need to validate the laboratory calibrated kinetic models against basin observations

post glacial seismic stratigraphy central great barrier reef australia a regional programme of continuous seismic boomer profiling in the central great barrier reef province has identified a widespread shallow seismic discontinuity reflector a which is interpreted as the pre holocene surface nine seismic facies units are distinguished primarily on the basis of the seismic records but also with the aid of additional criteria such as location and surface sediment types two units underlie reflector a and are pre holocene these units are interpreted as a permo carboniferous bedrock and b pleistocene tertiary sediments consisting of both shelf wide terrigenous units and carbonate mounds and platforms under present reefs seven units are post glacial and overlie reflector a these units are interpreted as c fluvial estuarine channel fill d relict delta front deposits e relict transgressive veneer f coastal coarse and g fine deposits h modern reef and i reef talus in general post glacial sediment cover is very thin and in many places on the mid shelf the pre holocene units crop out substantial post glacial accumulations are limited to protected coastal embayments and to offshore reef masses

the role of minerals in the thermal alteration of organic matter iv generation of n alkanes acyclic isoprenoids and alkenes in laboratory experiments a series of pyrolysis experiments utilizing two different immature oil prone kerogens type i green river formation kerogen type ii monterey formation kerogen mixed with common sedimentary minerals calcite illite or na montmorillonite was conducted to study the effects of minerals on the generation of n alkanes acyclic isoprenoids and alkenes during laboratory simulated catagenesis of kerogen the influence of clay minerals on the aliphatic hydrocarbons is critically dependent on the water concentration during laboratory thermal maturation under extremely low contents of water i e dry pyrolysis where only pyrolysate water is present c12 range n alkanes and acyclic isoprenoids are mostly destroyed by montmorillonite but undergo only minor alteration with illite both clay minerals significantly reduce alkene formation during dry pyrolysis under hydrous conditions mineralwater 2 1 the effects of the clay minerals are substantially reduced in addition the dry pyrolysis experiments show that illite and montmorillonite preferentially retain large amounts of the polar constituents of bitumen but not n alkanes or acyclic isoprenoids therefore bitumen fractionation according to polarity differences occurs in the presence of these clay minerals by this process n alkanes and acyclic isoprenoids are concentrated in the bitumen fraction that is not strongly adsorbed on the clay matrices the extent of these concentration effects is greatly diminished during hydrous pyrolysis in contrast calcite has no significant influence on the thermal evolution of the hydrocarbons in addition calcite is incapable of retaining bitumen therefore the fractionation of n alkanes or acyclic isoprenoids relative to the polar constituents of bitumen is insignificant in the presence of calcite

particle size distribution characteristics and pollution of heavy metals in the surface sediments of kuitun river in xinjiang china on the basis of analyzing particle composition of the surface sediments of kuitun river in xinjiang heavy metal concentrations of co cr pb ni mn cu and zn in different particle size fraction of the surface sediments were measured the enrichment and contamination levels of heavy metals in the surface sediments of different size were assessed based on both the single factor index method and nemerow integrated pollution index method the results showed that the surface sediments of the kuitun river were dominated by the particles with sizes lower than 250 m co cr mn cu and pb have a peak concentration in the range of 4 m the five heavy metals concentrations were 0 81 7 96 1 98 3 42 and 3 50 times their local soil background values respectively while ni and zn have a peak concentration in the range of 4 63 and 125 250 m respectively they were 2 13 and 1 49 times their local soil background values the results of evaluation showed that the heavy metals of the surface sediments in the range of 4 m were moderately polluted and the heavy metals of the surface sediments in the range of 4 63 63 125 and 125 250 m belonged to the category of low polluted

using nd sr isotopes and rare earth elements to study sediment provenance of the modern radial sand ridges in the southwestern yellow sea abstract the radial sand ridges rsrs in the southwestern yellow sea off the jiangsu coast east china have been intensively studied at least since 1975 despite decades of studies the provenance of the rsr sediments remains uncertain in this study the nd sr isotopic and ree geochemical compositions of residual sediments i e the acid insoluble fractions were investigated to determine the provenance of the rsr sediments the nd isotopic composition paas normalized ree patterns and characteristic parameters e g sm nd la sm n gd yb n were merely associated with source rocks but not with particle sorting while the sr isotopic composition and ree contents of residual sediments were affected by particle sorting in addition to source rocks the onshore rsr sediments originated mainly from mixing of the fine grained sediments from various parts of the offshore rsr in terms of ree geochemical and isotopic analyses isotopic and ree geochemical comparison further reveals that the rsrs off the jiangsu coast were fed chiefly by the dispersal of surface sediments from the yangtze river mouth surface sediments from the yangtze river mouth were directly dispersed to the rsrs along the jiangsu coast and significantly affected the seaward part of the offshore rsr and the old yellow river delta area by a northward branch of the changjiang diluted freshwater plume only minor quantities of surface sediments from the modern yellow river mouth were introduced into the rsrs by the jiangsu coastal current and mainly contaminated the landward part of the offshore rsr area our findings highlighted the potential of the nd isotopes with ree geochemistry to trace the provenance of coastal sediments

authigenic p formation and reactive p burial in sediments of the nazare canyon on the iberian margin ne atlantic profiles of different forms of sedimentary phosphorus were measured at four sites at the iberian margin ne atlantic which were chosen on the basis of differences in depositional environment a shelf site 113 m a mid slope station 1387 m and two stations at the head 396 m and base 3097 m of the nazarecanyon the sediment was sequentially extracted for fe bound p carbonate fluorapatite cfa biogenic p caco3 bound p and detrital ca p and non sequentially for total p and inorganic p where the difference between total and inorganic p was assumed to be organic p measurements of organic carbon and nitrogen citrate dithionite bicarbonate and citrate ascorbate bicarbonate extractable fe carbon oxidation rates fe reduction rates phosphate effluxes and sedimentation rates were used to quantify the cycling and burial of phosphorus at each site cfa formation was observed only in sediments of the nazarecanyon where enhanced rates of organic matter decomposition and fe reduction provided the necessary conditions the concentrations of reactive p were similar at all sites but the sediment accumulation rates differed greatly the high bulk accumulation rate at the base of the canyon results in a reactive p burial rate exceeding those estimated for continental margins including the iberian margin by an order of magnitude the estimated p burial efficiency is smallest at the slope station 3 24 reasonably high 63 86 at the shelf and head of the canyon stations and extremely high s 97 at the base of the canyon we propose that local depositories such as those at the base of canyons may be key sites for reactive p burial 2002 elsevier science b all rights reserved

geochemical constraints on the provenance of surface sediments of radial sand ridges off the jiangsu coastal zone east china abstract the jiang harbor centered radial sand ranges rsrs off the jiangsu coast are the largest in the yellow sea however the provenance of the rsrs remains controversial in this study we compare major and trace element geochemistry together with grain size and main mineral composition in carbonate free sediments from rsrs and potential sources onshore and offshore rsr sediments have different grain size characteristics onshore rsr sediments have mean grain sizes of 2 tio 2 li and partly in cs zn and some high field strength elements y zr nb pb and th while depleted in other elements offshore rsr sediments are complicated in geochemical compositions some of them have very high contents of high field strength elements and others are similar to onshore rsr sediments onshore and offshore rsr sediments have different controlling factors of geochemical compositions onshore rsr sediments are influenced by clay size minerals whereas offshore sediments are controlled by heavy minerals the identification of zr nb and ti zr vs k rb shows that onshore and offshore rsrs seem to have similar sources their differences in grain size are a result of hydrodynamic sorting the identification of elemental ratios reveals that sources of rsr sediments are variable in space and time and the inputs of the chinese rivers especially the old yellow river and the yangtze river are still dominant but the effect of the korean field cannot be neglected our findings also demonstrate the potential of elemental ratios such as zr nb and k rb as tracer pairs for provenance of sediments in the yellow sea

low temperature pyrolysis of green river kerogen geologic note the extrapolation of high temperature pyrolysis data to kerogen maturation conditions occurs over many orders of magnitude quite possibly the chemical kinetics of a high temperature regime may be different for a low temperature regime making the extrapolation meaningless we have mildly thermally treated green river kerogen to remove the low activation energy non oil bearing material low temperature 209 388 c isothermal reaction measurements on this refined material indicate that the same reaction kinetics for the oil production from green river kerogen obtained at high temperature 400 500 c are valid as low as 209 c the same arrhenius parameters apply over the entire range k 1 1013 exp 51300 rt sec 1 this means that the overall decomposition mechanism most probably a radical decomposition mechanism applicable at high temperature is also applicable at low temperature 209 c and perhaps geological i e 50 160 c temperatures olefins are initially produced in a ydrocarbon radical decomposition process we show that with time these olefins are converted to paraffins presumably using the residual hydrogen in the converted kerogen

spatial distribution of sedimentary p pools in a mediterranean coastal lagoon albufera d es grau minorca island spain the method for the sequential extraction of p proposed by jensen et al mcglathery k j marino r howarth r w 1998 limnol oceanogr 43 799 810 was used to study the spatial distribution of sedimentary p in superficial sediments of a mesohaline coastal lagoon located in a watershed formed by carboniferous sandstone in the western mediterranean minorca island spain dissolved inorganic phosphate ip dissolved organic phosphate op fe ca al and f were analyzed in the extractions to assess adequacy of this method to clay sediments the elemental composition of the solid phase al fe k ti si mg and ca was also analyzed to relate concentrations of p pools to the mineral composition samples from marine carbonated sediments rock and some materials of biological origin tubes of polychaete ficopomatus enigmaticus bivalve shell debris were analyzed for comparative purposes the sequential procedure allowed to extract almost all sedimentary p from carbonate sediments and biogenic debris but only 70 of total phosphorus tp from clay sediments and rock main ip pools in the lagoon were fe bound p 16 6 of tp caco3 bound p mainly from ficopomatus tubes 12 0 of tp and detrital carbonate fluorapatite 7 8 of tp the most abundant p pool was refractory p 20 3 of tp which appeared associated to the fe k al silicate fraction and to humic p this indicated that clay humic organic p complexes were the main p reservoir in the lagoon spatial distribution of p pools reflected differential sedimentation of allochthonous materials authigenic precipitation of fe oxides and fe bound p as well as the differential distribution of organisms such as ficopomatus

geochemistry of surface sediments in the archipelago sea sw finland a multiparameter and multivariate study this study investigates the geochemistry of soft organic rich brackish water surface sediments in the archipelago sea sw finland the area is one of the world s largest archipelagos and although it is scarcely populated frequent ship and boat traffic along with fish farming occurs from 76 sites 47 chemical elements were determined after aqua regia digestion other parameters determined were grain size water organic and nitrogen contents at sampling the sediments were visually classified into groups representing oxic anoxic and fluctuating intermediate oxic seafloor conditions the results show that the element concentrations are quite similar to other studies in the region but with clear signs of lower anthropogenic loading point source pollution was identified in one sample taken nearby a fish farm and a cable ferry this site was strongly enriched in cu zn and sn derived from chemicals used in either or both activities at the site overall the sediments can be divided into two groups that separate chemically and geographically one group contains more fine grained sediments that occur near shore while the other group contains more anoxic organic and sulfur rich sediments occurring more offshore the second group is interpreted to reflect material reworked from previous deposits as a result of shoaling of the area due to glacio isostatic land uplift the visual classes were included in both partial least squares regression plsr and pls discriminant analysis these analyses showed that the oxic and anoxic seafloor sediments can be predicted from the chemical variables and grain size distribution

oligocene miocene 28 13 ma climato tectonic evolution of the northeastern qinghai tibetan plateau evidenced by mineralogical and geochemical records of the xunhua basin abstract changes in sediment composition in the xunhua basin provide insights into the climatic and tectonic evolution of the northeastern qinghai tibetan plateau during the oligocene and miocene here we analyzed the clay mineralogy i e the proportions of smectite illite and chlorite and clay indicators bulk mineral composition i e the amounts of calcite quartz gypsum k feldspar plagioclase dolomite and halite and trace element indicators i e rb sr and ba sr ratios of sediments deposited from 28 to 13 ma in the xunhua basin to reveal the climate and or provenance changes the results suggest that significant changes in sediment provenance occurred at 25 1 ma and 21 6 ma caused respectively by initial uplift and accelerated uplift of the laji shan the xunhua basin experienced warm and humid conditions at 28 0 25 1 ma cool and dry conditions at 25 1 21 6 ma and somewhat warmer and wetter conditions at 21 6 19 2 ma followed by aridification in two steps at 19 2 ma and 13 9 ma the climate cooling event at 25 1 ma corresponds temporally to a major phase of uplift of central tibet relatively warmer and wetter conditions during the early miocene 21 6 19 2 ma are considered to record the influence of the asian summer monsoon and accelerated uplift of the laji shan the shift toward more arid conditions on the northeastern qinghai tibetan plateau at 19 2 13 9 ma was probably driven by uplift of the tibetan plateau and further aridification since 13 9 ma may reflect a weakening of the east asian summer monsoon and global climatic cooling

accumulation of phosphorus and heavy metals in the peel harvey estuary in western australia results of a preliminary study abstract concentrations of p and of heavy metals zn cd pb cu were determined in sediment cores from the peel harvey estuary in western australia two cores were extracted each representing one of the two basins of the estuary sediments were dated by surplus 210 pb by 137 cs and by changes in the fe s ratio increasing exports of p from the mainly agricultural catchments have resulted in more than a doubling of both total p and acid extractable inorganic p in sediments of the estuary accumulation of p in the estuary is less than expected for complete retention of inputs of p from the major tributaries historical data show that since 1950 average concentrations of dissolved inorganic p have approximately doubled in the peel inlet and increased by times seven in the harvey estuary increases in concentrations in surface sediments of acid extractable zn cd pb and cu are noticeable in the peel inlet and of zn and cd in the harvey estuary the greatest increase relative to background is shown by zn concentrations of extractable zn and cd in surface sediments are similar to those estimated from average concentrations in the water column for equilibrium adsorption to organic matter in sediments extractable pb is greater than estimated for equilibrium adsorption to sediments extractable cu is of the order of what can be expected for equilibrium adsorption to sediments in the peel inlet but is less than expected in the harvey estuary

late quaternary sedimentation on the great barrier reef continental shelf and slope east of townsville australia cores collected in a shelf to basin transect from northeastern australia document the stratigraphic development of late quaternary deposits low sea level to 120 m slope sedimentation is dominated by prograding fluvial deposits with wave dominated deltas forming on the shelf edge and upper slope the onset of sea level transgression into the excavated shelf river channels on the outer shelf resulted in estuarine sedimentation along an indented coastline 15 000 11 000 yrs b p reducing terrigenous sediment supplies to the slope on the outer shelf halimeda muddy sandy gravels were deposited over a pleistocene limestone erosional surface from about 10 500 yrs b p transgression submerged the limestone outcrops and estuaries of the middle shelf where coral reef complexes formed the outer and middle parts of the shelf thus became dominated by carbonate sedimentation while the inner shelf received fluvial input mixed with locally derived carbonates the sequence is bounded by an unconformity clearly marked by erosional down cutting the results of the study are combined with those of previous workers to develop transgressive and continued high sea level system tract models the latter continued high sea level model is used to extrapolate present high sea level sedimentation patterns into the future providing a model for comparison with ancient sequences which may also have formed in such a depositional environment

heavy metals in surface sediments of the continental shelf of the south yellow sea and east china sea sources distribution and contamination the heavy metals in surface sediments of the continental shelf of the south yellow sea sys and the east china sea ecs collected in 2016 were analyzed to assess the heavy metal distributions contamination status and likely sources the metal concentrations generally met the china marine sediment quality criteria however the enrichment factor and geoaccumulation index values clearly showed elevated cd and pb concentrations in the region cd and pb contamination occurred mostly to the southwest of the changjiang river mouth and to the east of the shandong peninsula because of rapid economic and industrial development the results are likely to be useful for authorities responsible for sustainable coastal zone management

phosphorus speciation in the sediment and mass balance for the central region of the great barrier reef continental shelf australia abstract solid phase p speciation has been determined in sediments from a transect across the central section of the continental shelf and slope of the great barrier reef gbr lagoon this region is characterized by a gradient of riverine aluminosilicate clay and silt nearshore seawards of which biogenic carbonate sediment predominates phosphorus speciation results show large variations along this transect organic p and authigenic apatite p are the major chemical forms of phosphorus in the central gbr continental shelf sediments post depositional reorganization of p was also observed converting organic p and iron bound p fe p to authigenic apatite p phosphorus burial rate was estimated from measurements of total p concentration and excess 210pb sediment mass accumulation rates burial efficiency varies significantly over the shelf inshore areas showed significant p remobilization from sediments to the water column up to 50 the mid and the outer shelf showed little evidence for remobilization except for coral reef platform sediments with more of the sediment p being in the less reactive authigenic apatite phases an appreciable fraction of this non labile authigenic apatite phase was identified as fish bone p sources and sinks over the central part of the gbr shelf were quantified using a mass balance approach this showed that coral sea shelf edge upwelling events are essential to satisfy the large p nutrient demand of the whole gbr lagoon p inputs due to upwelling events were greater than those contributed by local rivers over an average year

comparative analysis of morphological mineralogical and spectral properties of cryoconite in jakobshavn isbrae greenland and canada glacier antarctica we report the results of a comparative analysis focusing on grain size mineralogical composition and spectral reflectance values 400 2500nm of cryoconite samples collected from jakobshavn isbrae west greenland and canada glacier mcmurdo dry valleys antarctica the samples from the greenland site were composed of small particles clumped into larger rounded agglomerates while those from the site in antarctica contained fragments of different sizes and shapes mineralogical analysis indicates that the samples from jakobshavn isbrae contained a higher percentage of quartz and albite whereas those from canada glacier contained a higher percentage of amphibole augite and biotite spectral measurements confirmed the primary role of organic material in reducing the reflectance over the measured spectrum the reflectance of the samples from the antarctic site remained low after the removal of organic matter because of the higher concentration of minerals with low reflectance the reflectance of dried cryoconite samples in the visible region was relatively low e g between 0 1 and 0 4 favouring increased absorbed solar radiation despite high reflectance values in the shortwave infrared region the effect of the presence of cryoconite is negligible at infrared wavelengths where ice reflectance is low

geochemistry of rare earth elements in the mainstream of the yangtze river china abstract water suspended matter and sediment samples were taken from 8 locations along the yangtze river in 1992 the concentration and speciation exchangeable bound to carbonates bound to fe mn oxides bound to organic matter and residual forms of rare earth elements la ce nd sm eu tb yb and lu were determined by instrumental neutron activation analysis inaa the contents of the soluble fraction of rees in the river are low and rees mainly reside in particulate form in the particles the chondrite normalized distribution patterns show significant lree enrichment and eu depletion while normalized to shales both sediments and suspended matter samples show relative lree enrichment and hree depletion rees are relatively enriched in fine grained fractions of the sediments the speciation characteristics of rees in the sediments and suspended matter are very similar the amount of the five forms follows the order residual bound to organic matter bound to fe mn oxides bound to carbonates exchangeable about 65 to 85 of rees in the particles exist in the residual form and the exchangeable form is very low high proportions of residual rees reveal that rees in sediments and suspended matter are controlled by their abundances in the earth s crust carbonate fe mn oxide and organic fractions of rees in sediments account for 2 4 6 9 5 2 11 1 and 7 3 14 0 of the total contents respectively they are similar to those in the suspended matter this shows that carbonates fe mn oxides and organic matter play important roles during the particle water interaction processes by normalization to shales the 3 forms of rees follow convex shapes according to atomic number with middle ree sm eu and tb enrichment while light ree and heavy ree are depleted

optical characteristics of cryoconite surface dust on glaciers the relationship between light absorbency and the property of organic matter contained in the cryoconite

in situ quantification of supraglacial cryoconite morphodynamics using time lapse imaging an example from svalbard there is growing recognition of the significance of biologically active supraglacial dust cryoconite for glacial mass balance and ecology nonetheless the processes controlling the distribution transport and fate of cryoconite particles in the glacial system remain somewhat poorly understood here using a 216 hour time series of plot scale 0 04 m 2 images we quantify the small scale dynamics of cryoconite on longyearbreen svalbard we show significant fluctuations in the apparent cryoconite area and dispersion of cryoconite over the plot within the 9 day period of observations however the net movement of cryoconite across the ice surface averaged only 5 3 mm d 1 high resolution measurements of cryoconite granule motion showed constant random motion but weak correlation with meteorological forcing factors and no directional trends for individual particle movement the high resolution time series data suggest that there is no significant net transport of dispersed cryoconite material across glacier surfaces the areal coverage and motion of particles within and between cryoconite holes appears to be a product of differential melting leading to changes in plot scale microtopography local meltwater flow dynamics and weather dependent events these subtle processes of cryoconite redistribution may be significant for supraglacial albedo and have bearing on the surface energy balance at the glacier scale

climate sensitivity of glaciers in southern norway application of an energy balance model to nigardsbreen hellstugubreen and alfotbreen three glaciers in southern norway with very different massbalance characteristics are studied with an energy balance model of the ice snow surface the model simulates the observed mass balance profiles in a satisfactory way and can thus be used with some confidence in a study of climate sensitivity calculated changes in equilibrium line altitude for a 1 k temperature increase are 110 108 and 135 in for nigardsbreen hellstugubreen and alfotbreen respectively the corresponding changes in mass balance averaged over the entire glacier area are 0 88 0 715 and 1 11 in year water equivalent runs with an ice flow model for nigardsbreen to which calculated mass balance profiles are imposed predict that the front will advance by 3 km for a 1 k cooling and will retreat by as much as 6 5 km for a 1 k warming the response to a 10 increase in precipitation would be a 2 km advance of the snout whereas a 4 km retreat is predicted for a 10 decrease this large sensitivity as compared to many other glaciers is to a large extent due to the geometry of nigardsbreen

temporal variations of cryoconite holes and cryoconite coverage on the ablation ice surface of qaanaaq glacier in northwest greenland cryoconite holes are water filled cylindrical holes formed on ablation ice surfaces and commonly observed on glaciers worldwide temporal changes of cryoconite holes characteristically 5 cm in diameter were monitored with a time lapse interval camera over 15 d during the melting season on qaanaaq glacier in northwest greenland the holes drastically changed their dimensions and synchronously collapsed twice during the study period when the holes collapsed the coverage of cryoconite on the ice surface increased from 1 0 to 3 5 in the field of view of the camera and then decreased again to 0 4 after the holes reformed comparison with meteorological data showed that the collapses occurred in cloudy and rainy or windy weather conditions corresponding to low shortwave solar radiation 68 126 w m 2 40 55 of the incoming flux in contrast holes developed in sunny conditions correspond to high solar radiation 186 278 w m 2 63 88 results suggest that the dimensions of holes drastically changed depending on the weather conditions and that frequent cloudy warm and windy conditions would cause a decay of holes and weathering crust inducing an increase in the cryoconite coverage on the ice consequently darkening the glacier surface

millennial scale evolution of elemental ratios in bulk sediments from the western philippine sea and implications for chemical weathering in luzon since the last glacial maximum abstract to reconstruct the chemical weathering history in luzon philippines since the last glacial maximum lgm major and trace elements ti al fe k ba rb v sc cr and th and grain size were determined for core md06 3054 as well as the bulk and detrital fractions of three core top samples from the western philippine sea wps in combination with previously published sr nd isotopes our new results indicate that ti normalized elemental ratios in the study samples were not controlled by the quantity of biogenic authigenic or diagenetic materials sediment provenance or grain size instead variations in ti normalized elemental ratios mainly reflect changes in chemical weathering intensity with lower values representing stronger chemical weathering in luzon to assess long term integrated chemical weathering patterns we defined a stacked chemical weathering index scwi based on all elemental ratios in the study core downcore scwi records indicate that sediments deposited during the lgm underwent a degree of chemical weathering equal to that during the holocene and sediments deposited during the last deglaciation exhibit rapid changes in chemical weathering with higher intensity during the heinrich event 1 h1 and younger dryas yd and lower intensity during the bolling allerod b a in the wps these observations are in excellent agreement with chemical weathering proxies such as the k al ratios and chemical index of alteration when applied to the same core we infer that persistent sea level lowstand and induced reworking of poorly consolidated sediments on the eastern luzon continental shelf during the lgm accounted for equal or slightly stronger chemical weathering for the lgm sediments relative to the holocene sediments rainfall rather than air temperature in luzon was responsible for the rapid changes in chemical weathering during the last deglaciation with higher precipitation generating stronger chemical weathering during the h1 and yd than during the b a our observations combined with existing data suggest that strong weathering of marine sediments during colder intervals of the middle late quaternary is likely to be a general feature of the tropical west pacific although the mechanism that underlies this phenomenon remains controversial

paleoceanographic changes in the ulleung basin east japan sea during the last 20 000 years evidence from variations in element composition of core sediments a millennial scale paleoceanographic record of the ulleung basin in the southern part of the east japan sea es for the last 20 000 years was reconstructed based on variations in the element compositions of core sediment most of the elements showed relatively wide content ranges throughout the core largely because of different sediment types their grain size spectra biological components and geochemical conditions i e redox conditions in particular biogenic components ca sr ba and caco 3 and some minor elements cu mn mo u cd zn and v revealed three distinct intervals of major paleoceanographic changes interval 1 similar to 18 9 3 kyr bp is characterized by a rhythmic alternation of dark and light colored sediment bands distinctive differences in the abundance of organic carbon carbonate and redox elements between the dark and light colored sediment layers are probably attributable to especially those associated with bottom water redox variations combined with the enhanced primary productivity and water stratification in the ulleung basin

variations in trace element including rare earth element concentrations with grain sizes in loess and their implications for tracing the provenance of eolian deposits the concentrations of rare earth elements rees and other 28 trace elements were determined in seven grain size fractions from four loess samples collected from the tibetan plateau the sichuan basin and the chinese loess plateau the results indicate that concentrations of rees except for heavy rare earth elements hrees are almost grain size independent however rees show clear fractionation with grain size middle rare earth element mree depletion increases with decreasing grain size whereas hree enrichment increases with decreasing grain size excluding rees and y most of the other trace element concentrations tend to increase with decreasing grain sizes the trace element geochemistry indicates that the potential sources of eolian deposits from the sichuan basin the chinese loess plateau and the tibetan plateau differ from one another this comparative study confirmed that the eolian materials from the asian continent are the source of the terrigenous component of the central north pacific sediments and the loess from the chinese loess plateau could represent the average composition of eolian dust from the asian continent in contrast the eolian deposits in the sichuan basin and in the tibetan plateau are mainly of local origin with short distance eolian transport

distribution of phosphorus in sediments from tomales bay california abstract the distribution of phosphorus among six sequentially extracted fractions was determined in suspended load and bottom sediments from lagunitas creek and tomales bay california the sequential extraction scheme was a modification of the sedex scheme of ruttenberg 1992 using the surfactant sodium dodecyl sulfate sds to extract organic phosphorus sds effectively removed organic phosphorus from sediments with little interference from inorganic phosphorus containing phases the distribution of phosphorus in the sequentially extracted fractions was similar in suspended load and bottom sediments collected from lagunitas creek and the bay the concentration of phosphorus in cdb extractable iron oxide phases was below detection in all samples most of the phosphorus 70 80 contained in these sediments was found in the organic and residual phases porewaters from sediment cores were analyzed for dissolved inorganic carbon ammonium phosphate sulfate iron calcium and fluoride within bay sediments porewaters were depleted in phosphate relative to dissolved inorganic carbon and ammonium suggesting that phosphate released from organic matter decomposition is being removed from the porewaters sequential extraction results suggest that approximately 15 of the phosphate released from organic matter decomposition could be removed from the porewaters by adsorption into the exchangeable phosphorus fraction and an additional 3 may be precipitated as authigenic phosphate minerals the remaining phosphate 82 released from organic matter decomposition must be either taken up within the sediment mixed layer 0 40 cm or escapes to the overlying water column

visible and near infrared reflectivity during the ablation period on peyto glacier alberta canada models for calculating glacier mass balance are sensitive to surface reflectivity variation fieldwork carried out on peyto glacier alberta canada contributes to the data set available for ice reflectivity parameterization in such models hemispherical reflectivity in the visible and near infrared parts of the solar spectrum was obtained for rock snow and three contrasting glacier surfaces to examine temporal and spatial variations glacier ice near infrared reflectivity displays only minor spatial variation 0 12 0 17 in comparison with the visible range 0 23 0 40 the latter being influenced primarily by surface impurity content surface roughness is of minor importance compared with impurities temporal variation of reflectivity was weak at all glacier ice and rock locations slight variations observed were due to changes in either solar zenith angle or cloud amount snow reflectivity displayed pronounced diurnal asymmetry and a larger response to cloud cover the minimal temporal variation in glacier ice reflectivity simplifies its parameterization this behaviour is additionally useful for satellite based measurements of the reflectivity field on larger glaciers as images obtained within a 6 h window centred on solar noon are likely to yield values which are within 2 3 of daily mean values

processes controlling the geochemical composition of the south china sea sediments during the last climatic cycle abstract sediments of the upper 28 2 m of ocean drilling program odp site 1145 from the northern south china sea scs were analyzed for their geochemical composition most of the major and trace elements exhibit significant fluctuations at glacial interglacial scales implying a close relation with regional and global climate change al normalized elemental ratios can be subdivided into three principal components pc pc1 e g ca al ba al sr al displays significant glacial interglacial variation and is related to paleoproductivity in the northern scs pc2 e g k al mg al rb al is associated with the degree of chemical weathering in the source regions and shows little glacial interglacial variation pc3 e g ti al zr al reflects the relative contribution of coarse and fine grained materials in the terrigenous components of the scs sediments likely associated with changes in sea level and monsoon induced fluvial input spectral analyses indicate that paleoproductivity i e ba al in the south china sea lags hulu sanbao speleothem 18o record an indicator of annual average meteoric precipitation by 102 and indian summer monsoon multi proxy stack by 23 at the precession band indicating a close relationship with the indian summer monsoon however the chemical weathering degree in the source area pc2 is not sensitive to monsoon related changes at the precession band during the last climatic cycle

massive siliciclastic discharge to slopes of the great barrier reef platform during sea level transgression constraints from sediment cores between 15 s and 16 s latitude and possible explanations abstract the northeast australian continental margin including the great barrier reef gbr platform provides an outstanding modern analogue for understanding sedimentation in tropical mixed siliciclastic carbonate depositional systems previous studies of cores from this margin have suggested that in contrast to widely accepted models maximum siliciclastic fluxes to slopes over the last 30 ky occurred when sea level transgressed the shelf ca 11 7 ka rather than when sea level was at a lowstand before 18 ka however climate and bathymetry can affect regional sediment deposition significantly and the cores examined to date have come from the southern queensland trough where the margin has a wet tropical climate and a broad shelf 50 km with gradual slopes in this study we examine the abundance and accumulation of siliciclastic material in four cores from lower slopes of the northern queensland trough where rivers drain a drier region and debouche onto a narrow shelf with steep incised slopes similar to previously examined cores all cores contain a dark greyish brown horizon within the upper few meters this horizon represents a low in carbonate content and corresponding high in siliciclastic material primarily clay and oxygen isotope stratigraphy shows that it was deposited during late transgression nominally between 11 and 7 ka moreover mass accumulation rate calculations demonstrate that this horizon reflects a significant rise in siliciclastic fluxes when combined with the previous work to the south it appears that slopes all along a large portion of the northeast australian continental margin received greatly enhanced inputs of siliciclastic material during late transgression independent of proximal climate and bathymetry two general explanations are offered for this observation 1 climate change induced highly variable riverine discharge over the past 30 ky with a prominent maximum coincident with late transgression or 2 the shelf stores large quantities of siliciclastic sediment during lowstand and releases this material to the slope during late transgression in either case siliciclastic accumulation on the northeast australia continental margin behaves completely opposite to predictions from conventional models

multi element geochemistry of sediments from the pearl river system china sediment samples were taken along the west north and east rivers of the pearl river system at 28 locations in 1998 and a total of 49 elements were determined by icp aes icp ms and inaa the probability features of the datasets were studied and the average concentrations of these elements in sediments of the three rivers were calculated significant differences in element concentrations among the three rivers were observed and the results were confirmed by statistical tests including analysis of variance anova kruskal wallis test and t test spatial distribution maps of element concentrations were produced using a geographical information system gis the immobile trace elements such as sc ti v cr mn fe co and ni are enriched in the west river where limestone dominates the rock types in the watershed because of the strong weathering immobile trace elements are enriched and reside in secondary minerals of the weathering products all three rivers have high concentrations of rare earth elements rees because of strong weathering but relatively higher concentrations of rees are observed in sediments of the east river where granite dominates the rock type granite contains high concentrations of rees and the sediments have inherited this feature from their bedrock alkaline element li na k rb and cs concentrations are elevated in sediments of the east river these may reside in granitic primary minerals relatively high concentrations of alkaline earth elements mg ca sr and ba are observed in the west river inherited from the limestone bedrock high pb and bi concentrations are found in the north river and are caused by pb mineralization and the discharge of a smelter in the upper reaches of the river however statistical tests did not indicate a significant difference between pb concentrations in the north river and the other two rivers which suggests that statistical results should be carefully used and explained

major and trace element variations of the sediments at odp site 1144 south china sea during the last 230 ka and their paleoclimate implications abstract we present here the major and trace element data of the sediments at odp site 1144 of the last 230 ka with time resolution about 1 5 kyr to investigate their relations to the climate changes estimated from tio2 and cao contents over 70 in weight of the sediments are terrestrial materials and caco3 abundance ranges between 7 and 19 the variation patterns of some of the major elements such as al fe k mg and mn and some of the trace elements such as the alkali elements such as rb and cs the alkali earth elements such as ba and most transition metals such as sc v co cr zn well match that of the oxygen isotopes of the planktonic foraminifer after normalized with ti with higher values during interglacial periods and lower values during glacial periods whilst the na abundance exhibits inverse variation patterns with lower values during interglacial periods and higher values during glacial periods however most refractory elements such as y zr nb hf ta rees th and u do not show such patterns these agree well with the behaviors of these elements during chemical weathering therefore the changes of chemical weathering intensity in south china the source area of these sediments may account for such variation patterns during interglacials wet and warm climate might occur at south china which resulted in stronger chemical weathering and dry climate might occur during glacials which resulted in weaker chemical weathering such paleoclimate interpretation agrees with those from other paleoclimate proxies such as pollen records indicating that change of the east asian monsoon especially change of the winter monsoon is the key for such paleoclimate variation patterns

temporal and spatial variations in spectral reflectance and characteristics of surface dust on gulkana glacier alaska range spectral reflectances in the visible to near infrared wavelength range 350 1050 nm were measured on the surface of gulkana glacier alaska range alaska usa at six different elevations from may to september 2001 the measurements showed variable spectral reflectances on the glacier surface and the spectra changed over time and elevation the spectra in may were those of a typical wet snow surface the reflectance ranged approximately from 0 4 to 0 8 and generally decreased as the wavelength increased as snowmelt proceeded the reflectance gradually fell and specific absorptions appeared in the spectrum at wavelength ranges of 400 600 and 670 680 nm corresponding to a red snow surface due to snow algal bloom as the ice surface was exposed the spectrum finally shifted to a lower 0 1 0 4 and flat reflectance curve typical of an ice surface contaminated with dust analyses of the dust on the glacier surface showed that its quantity and characteristics changed spatially and seasonally and were correlated with spectral albedo the results showed that the temporal and spatial variations in spectral reflectance on this glacier are due not only to physical properties of the glacier surface but also to biogenic materials on the surface e g red colored snow algal cells and cryoconite

rapid quantification of cryoconite granule geometry and in situ supraglacial extents using examples from svalbard and greenland supraglacial dust cryoconite is an important but poorly understood component of the glacial system there is a lack of primary data on cryoconite form extent and dynamics here we present a suite of rapid low cost methodologies for quantification of granule geometry and supraglacial cryoconite coverage using image data captured by commercially available digital cameras we develop robust transferable protocols for analysis of 1 cryoconite granule geometry major axis feret diameter circularity 2 centimetre metre scale supraglacial extent m2 cryoconite m 2 surface and 3 temporal change in supraglacial extent at hourly intervals over several days image processing methodologies were developed using the public domain software imagej manual supervised controls were used to estimate sources of error and measurements then automated using simple scripting tools macros fully automated processing successfully identified 90 of a sample of isolated granules ranging between 2 5 and 39 2 mm with uncertainties of 20 particle sphericity inferred from circularity decreased as particle size increased supraglacial cryoconite extent was obtained with a mean uncertainty of 37 and 22 for data from field sites in greenland and svalbard respectively these methods will facilitate acquisition and analysis of datasets for cryoconite across a range of spatial scales supporting research into cryoconite impacts on supraglacial hydrological connections nutrient and carbon cycling and initiation of primary succession in deglaciating environments

grain size control of mineralogy and geochemistry in modern river sediment new guinea collision papua new guinea the new guinea collision includes diverse sediment source areas associated with arc continent collision to the west of the solomon sea triple junction and with subduction of oceanic crust to the southeast and northeast of the triple junction twenty seven sediment suites each comprising up to seven gravel sand and mud samples from the same locality were analysed to determine mineralogical and geochemical variation with changing grain size this paper deals primarily with the mineralogical variation compositional variation from coarse to fine grained fractions is generally 50 of each variable s abundance with many variables showing greater than 100 variation in contrast variation due to analytical error is generally less than 10 between year variation generally ranges from 15 to 25 and downstream variation is generally less than 50 petrographic results indicate that sediment composition is fundamentally dependent on grain size the principal control on sediment composition is mechanical weathering of rock fragments and compositional sorting of the constituent mineral phases while the gazzi dickinson method for point counting sediment reduces modal variability and in most cases provides robust provenance discrimination it is unsuitable for discerning faint source rock signatures often revealed by grain size dependent compositional variation only the upper plate magmatic arc provenance signature is evident from recalculated modal and geochemical data and that signature does not reflect the modern upper plate magmatic arc detailed petrographic analysis of grain types as opposed to recalculated modal or geochemical data is required to elucidate both upper and lower plate provenances and discriminate between ancient and contemporary arc provenances

the distribution of phosphate in sediments of the johnstone rivers catchment estuary system north queensland australia this paper presents results from a preliminary assessment of phosphate loaded sediment occurrence and distribution of the johnstone rivers system in the cairns section of the great barrier reef marine park total po4 concentrations in channel sediments show a substantial increase from rainforest to agricultural settings and inorganic po4 concentrations are much higher in the tributaries draining agricultural land than in either main river it was also found that total po4 concentrations are much higher in the dry season than in the wet season the results of this study indicate that agricultural practices have a noticeable influence on the po4 content of riverine and estuarine sediment of the johnstone rivers despite this the estuarine offshore and reef sediment data suggest that the phosphate loss from agricultural land in the johnstone rivers catchment is unlikely to affect the nutrient status of the great barrier reef reworked fine grained phosphate bearing sediment may however have an impact on nearshore marine ecosystems

biogeochemical evolution of cryoconite holes on canada glacier taylor valley antarctica 1 the cryoconite holes of the mcmurdo dry valleys are simple closed biogeochemical systems involving water ice mineral and organic debris which serve as ecosystems for consortia of microorganisms this study is the first to document the seasonal and annual chemical evolution of solutes in cryoconite holes samples of glacier ice frozen cryoconite holes and those containing water were collected during the austral summer of 2005 2006 the isolation age was calculated from the excess cl in the holes and varied from 0 to 5 years a consistent with the last hot summer when the cryoconite holes were open to the atmosphere the holes progressively deepen with isolation age variations in dic doc k and so42 suggest that dissolution of primary minerals in the cryoconite debris cyclical precipitation and dissolution of secondary carbonates net photosynthesis over summer and net respiration during the autumnal freeze are the principal reactions which perturb the seasonal and annual solute concentrations in the holes doc is generated in the holes at a rate of 7 5 g c cm 2 a 1 and non sea salt k accumulates in frozen holes at a rate of 0 073 eq cm 2 a 1 we infer that c cycling is complex even in these otherwise simple systems

geochemistry of holocene salt marsh and tidal flat sediments on a barrier island in the southern north sea langeoog north west germany abstract the barrier islands of the southern north sea were formed during the holocenesea level rise these islands form part of a highly dynamic environment whoseevolution continues today subjected to sea level changes tides and stormevents the sedimentary record re ects processes occurring under varyingenergy conditions this article presents geochemical mineralogical anddiatom investigations carried out in the salt marsh of the east frisian barrierisland of langeoog which is re exposed to a rising sea level due tode embankment the major aim of this study is to improve the knowledge ofthe sedimentological and geochemical development of these deposits underthe in uence of sea level rise with a special focus on the geochemistry anddistribution of heavy mineral associated elements correlation diagramsbetween feo tio 2 and mno as well as ternary plots al 2 o 3 sio 2 zr ortio 2 clearly indicate the variable appearance of heavy minerals in differentlithological facies comprising marsh soil mixed and sand at and relocatedbeach sands a dominating abundance of ilmenite followed by zircon garnetsand some other heavy minerals is evidenced by scanning electron microscope energy dispersive x ray measurements the data presented here suggests thatthese geochemical proxies are useful tools for characterizing depositionalenergy conditions increasing depositional energy is evident for the lithologicalunits in the following order marsh soil mixed at sand at and relocatedbeach sand the energetic conditions during sediment deposition as well asthe sedimentary history are con rmed by diatom analyses as an additionalindependent indicator depending on source rock composition thegeochemical parameters used in this study may also help to investigatedepositional energy regimes of other siliciclastic sedimentary systems keywords depositional energy diatoms heavy minerals inorganicgeochemistry north sea salt marsh tidal at introductionthe depositional history of the barrier islands andadjacent tidal at system of the southern northsea coast was directly related to climate changesduring the holocene sea level rise the lasttransgressive cycle started in the weichselianlate glacial and continues today as evidenced bysedimentology 2012 59 337 355

influence of water column anoxia on the elemental fractionation of carbon and phosphorus during sediment diagenesis abstract organic carbon oxidation and benthic total phosphorus flux measurements from sites covering a range of bottom water oxygen concentrations have been compiled the data show that p regeneration relative to carbon oxidation is much more extensive in sediments overlain by oxygen depleted waters these results are consistent with studies showing that low oxygen bottom water concentrations correlate with reduced total phosphorus burial efficiencies and enhanced organic carbon burial efficiencies based on these observations a positive feedback is proposed between water column anoxia enhanced benthic phosphorus regeneration and marine productivity this feedback may help explain the widespread accumulation of organic rich marine sediments from anoxic waters observed in the geologic record

tracing the source of sediment and phosphorus into the great barrier reef lagoon neodymium and strontium isotopic systematics show that terrestrial phosphorus p entering the inner great barrier reef gbr is dominated by the transport and dispersal of fine grained basaltic soils soils derived from alkali basalts have high total p 3000 4000 mg kg and distinctive 143 nd 144 nd isotopic signatures ondv 3 to 5 while the more common palaeozoic granitic metamorphic soils have much lower total p 300 600 mg kg and 143 nd isotopic signatures ondv38 the nearshore environment 6 5 km from the coast is dominated by coarse grained graniticderived fluvial detritus while s 20 km from the coast carbonate rich sediments with increasing contributions from basaltic components become more important in the offshore sites adjacent to coral reefs it is shown that basaltderived sediments can account for s 90 of the terrestrial p although making up less than half of the total terrigenous detritus equilibrium phosphorus concentration measurements on the marine sediments indicate that p enters the gbr lagoon via a two stage process firstly during episodic flood events p is transported into the gbr lagoon on p retentive fine grained suspended sediments with only minor desorption of p occurring in the low salinity flood plumes desorption of p mainly occurs over longer timescales predominantly in regions of sediment anoxia with release of po 33 4 directly into marine pore waters probably via reduction of ferric phosphates and subsequent release into the water column by re suspension this process causes p depletion of the re deposited sediments 2003 elsevier science b v all rights reserved

delays of supraglacial runoff from differently defined microbasin areas on the peyto glacier microbasin runoff experiments were conducted on ice surfaces of the peyto glacier during the 1971 and 2008 ablation seasons when half hourly measurements of net radiation wind speed temperature vapour pressure and supraglacial runoff were obtained on warm sunny days with daily mean temperatures 6 1 10 1 c and daily total ablation amounts of 43 95 mm net radiation contributed almost 70 of the melt energy in 1971 and nearly 60 in 2008 with the remainder supplied by turbulent transfers of sensible and latent heat thus the two experiments are similar in finding that radiation dominates surface melt energy inputs to microbasin runoff outputs they differ with respect to area definitions and microbasin shapes 1 a purposely delineated rhomboidal area 30 m long 15 m wide covering 386 m2 in 1971 2 a naturally delineated elongated area approximately 600 m long 2 m wide covering an estimated 1200 m2 in 2008 three 24 hour periods beginning at 0700 h were obtained for experimental work in 1971 and 8 such periods in 2008 supraglacial runoff was modelled by passing melt energy water equivalents through a simple storage reservoir and forcing closure with measured runoff by optimising for delay time optimal times of 1 2 h were found for 1971 and 7 5 11 5 h for 2008 thus indicating a major difference between the runoff responses of the two microbasins it is possible that different basin shapes may explain the contrasting delay times perhaps because different shapes signify different flow connections to meltwater storage in the weathering crust if the elongated microbasin response is typical of the elemental hydrological response unit of the melting ice surface distributed glacier runoff models should incorporate it as part of the model structure copyright 2011 john wiley sons ltd

multielement geochemistry of offshore sediments in the southeastern yellow sea and implications for sediment origin and dispersal abstract in total 116 surface sediments were collected from an offshore area of the southeastern yellow sea including a large mud belt southeastern yellow sea mud seysm and analyzed for grain size and geochemical composition organic carbon and 42 elements principal component analysis revealed that elemental compositions of the offshore sediments were mostly controlled by common aluminosilicate clay minerals and quartz most elements heavy minerals hf zr u th rare earth elements rees biogenic calcium carbonates ca sr feldspar and mica k ba pb and mn oxides mn oxide coatings on sand grains notably total ree concentrations may be associated with heavy minerals possibly zircon and monazite especially in silty grains even though heavy ree hrees concentrations are more strongly controlled by clay minerals in muddy sediments the diagnostic discrimination plots of geochemical compositions e g fe vs al mg vs al light ree vs hree and la lu ucc vs la y ucc suggested that the offshore sediments especially in seysm deposits were composed of a mixture of korean river derived silts and chinese river derived clays this demonstrated that chinese river sediments especially clay particles largely contributed to the formation of the giant mud belt in the korean coastal area furthermore the observed geochemical end members provide new markers of sediment provenance which can be used to track dispersal patterns and sediment limits from chinese and or korean rivers