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Abstract Deep-sea microorganism research has become a hot topic in life science, owing to its special value in high pressure and low temperature environment. If not kept the in-situ low temperature and high pressure, it will cause the microorganism to lose its activity and lead to a waste of resources. A freeze-sediments valve presents a promising solution to maintain the low temperature and high pressure in situ, improve the success rate of sampling and shorten the sampling time. A series of experiments were conducted to characterize the freeze-sediments valve, including the sampling time without leakage, adaptation to different sediments and the effect of the length, etc. Most important of all, temperature change of sediments is observed in all experiments. Experimental results indicated that the freeze-sediments valve was formed in 5 min without leakage and the freeze-sediments valve could be applied to different sediments without limitations on sediments type and mineral content. Considering the pressure retaining capacity and formation time of freeze-sediments valve, it was found that the freeze-sediments valve with a length of 60–80 mm has good pressure retaining capacity whose value was 41.3–48.4 Mpa and short formation time which was 5 min. Precooling the sampler could be used to shorten the sampling time in the actual environment application. This sampling technique can play a vital role in maintaining in-situ low temperature at −2 to −4 ° Celsius in all the experiments. According to the tests, the sampling technique based on the freeze-sediments valve had the potential to solve the problem of keeping in-situ temperature, low sampling success rate and long sampling time in the future. [ABSTRACT FROM AUTHOR]

Fluvial strata deposited before the advent of land plants are commonly sheet‐like in geometry, lacking in channel forms. Although some pre‐vegetation strata contrast strongly with fluvial strata from later eras, the characterization of pre‐Devonian fluvial drainage systems remains incomplete. Field studies of the fluvial facies and architecture of the Series Rouge are presented to identify the products and processes of fluvial deposition occurring at high latitudes in the early Cambrian. Three different depositional styles or facies associations are recognized. Facies Association 1 is the most abundant (67%) comprising repetitively stacked sheets of trough cross‐stratified sandstone interpreted to represent the preferential preservation of the deepest parts of low sinuosity, braided river channels, 4 to 6 m deep. Facies Association 2 is also common (30%) and displays more complex facies sequences that include stacked sheets of trough cross‐strata, sets of large‐scale tabular cross‐strata, planar strata and subordinate mudstone. These facies are interpreted to reflect deposition in braided rivers with deeper channels, 6 to 8 m deep. These channels were more sinuous and subject to steady lateral migration which resulted in preservation of both deep and shallow parts of the river. Facies Association 3 is uncommon (3%) comprising interbedded sequences of cross‐stratified sandstone and mudstone interpreted to reflect deposition on a muddy coastal plain in a mixture of braided and meandering channels, 1 to 3 m deep. The fluvial strata of the Series Rouge indicate that these pre‐vegetation drainage systems were predominantly braided fluvial in origin. However, the style of braided fluvial deposition varied according to discharge and valley slope, the braided rivers becoming more migratory with decreasing slope. Meandering channel deposition was locally evident but was restricted to channels of low discharge crossing low gradient muddy coastal plains. [ABSTRACT FROM AUTHOR]

The origin of recent mud deposits as well as the coastal turbidity maximum in the French-Belgian-Dutch nearshore area of the southern North Sea is still under debate in the literature. Some models favor the erosion of the Cretaceous chalk cliffs along the English Channel and subsequent NE ward directed transport, other models focus on the erosion of Eocene to earliest Oligocene, and Pleistocene to Holocene clays outcropping on the seafloor off the Belgian coast. In order to validate these hypotheses, the detailed qualitative and quantitative clay mineral composition of these sediments was used as a provenance indicator. By comparing the clay mineral composition of the mud deposits and the associated suspended particulate matter (SPM) with the composition of potential nearby and more remote sources such as the present day marine environment, estuaries and rivers, coastal erosion areas and the geological substratum, the origin of the mud deposits and the SPM could be traced. Results showed that only the clay composition of the Scheldt estuary coincides with those of the mud deposits and the coastal turbidity maximum and that all other potential sources could be excluded. Our data suggest that the clay mineral composition of the mud deposits has a similar composition since at least about 100.000 years, indicating that these deposits originate from a paleo-Scheldt river rather than from the recent river system, as the present-day Scheldt estuary is not source of fine-grained sediments. The present-day SPM in the Belgian-Dutch nearshore area originates mainly from the erosion and resuspension of the existing mud deposits situated in the Belgian nearshore. This study demonstrates the value and suitability of quantitative bulk and clay mineralogy techniques in sediment provenance studies and highlights the importance of incorporating the recent geological history in hydrodynamic studies of sedimentary basins. [ABSTRACT FROM AUTHOR]

Lithofacies zoning is described for the first time for the Neo- and Eopleistocene of the Bering Sea. Four lithofacies sedimentation zones are distinguished: (I) terrigenous; (II) siliceous-terrigenous; (III) siliceous, and (IV) volcanoterrigenous ones. Corresponding maps were treated using Ronov volumetric method to quantify sedimentation parameters for distinguished lithofacies zones (subzones) and types of Pleistocene sediments. It was revealed that terrigenous sediments predominate over other sediments. Accumulation of the terrigenous sediments was more intense (by 1.4 times) in the Neopleistocene than in the Eopleistocene. The sedimentation rate of siliceous sediments of the Bowers Ridge in the Eopleistocene was two times higher than in the Neopleistocene. [ABSTRACT FROM AUTHOR]

The choice of areas for nature conservation involves the attempt to maximize the benefits, whether by carrying out an economic activity or by the provision of Ecosystem Services. Studies are needed to improve the understanding of the effect of the extent and position along the watershed of restored areas on soil and water conservation. This study aimed to understand how different restoration strategies might reflect in soil conservation and sediment retention. Using InVEST tool, sediment transport was simulated in a small 12 km2 watershed (Posses River, in Southeast Brazil), where one of first Brazilian Payment for Ecosystem Services (PES) projects is being carried out, comparing different hypothetical restoration strategies. With 25% of restoration, sediment export decreased by 78% for riparian restoration, and 27% for the steepest slopes restoration. On the other hand, the decrease in soil loss was lower for riparian restoration, with a 16% decrease, while the steepest slopes restoration reduced it by 21%. This mismatch between the reduction of sediment export and soil loss was explained by the fact that forest not only reduces soil loss locally but also traps sediment arriving from the upper parts of the watershed. While the first mechanism is important to provide soil stability, decreasing the risk of landslip, and to maintain agricultural productivity, the second can improve water quality and decrease the risk of silting, with positive effects on the water reservoirs at the outlet of the watershed. This suggests that Riparian and the Steepest Slopes restoration strategies are complementary in the sense of preventing sediments from reaching the water bodies as well as protecting them at their origin (with the reduction of erosion), so it will be advisable to consider the two types of restoration. [ABSTRACT FROM AUTHOR]

The risk assessment code (RAC) is a common method for assessing heavy metal (HM) mobility and their potential health risks, based on HM total concentration and chemical speciation. In this study, both the RAC and the influence of ambient environmental factors were investigated in a river sediment system. Sixty-eight sediment samples were collected from the main river system in Shanghai, China. The total concentration and chemical speciation of Cu, Zn, Ni, Pb, Cd, Cr, As, and Hg were determined in the samples. The influence of sediment environmental factors, such as acid-volatile sulfide (AVS), Fe & Mn, and total organic carbon (TOC), on total metal concentrations and speciation was also investigated. The relationship between the main environmental media and distribution of HMs was discussed using PCA and NMDS. The transfer-transformation behaviors of Pb, Ni, and Cr were mainly controlled by AVS and TOC while Zn, Cu, and Cd were influenced by Fe & Mn and TOC. The relationship between the RAC value of HM and environmental factors revealed that 7% of Cr, 23% of Ni, and 15% of Pb had a high risk of mobility at TOC values below 3.5% and sulfite contents below 10 mmol/kg. In comparison, 29%, 10%, and 10% of Zn, Cu, and Cd, respectively, had a high risk of mobility at TOC < 3.5% and Fe & Mn content > 4 × 10 5 mg/kg. Evidently, the chemical fractions of HM had a strong dependence on the S, Fe, Mn, and organic compounds in the sediment. This study provides a promising pathway for the rapid evaluation of potential risks from HMs in river sediments. [ABSTRACT FROM AUTHOR]

The Late Cenozoic East Asian winter monsoon (EAWM) enhancement has been attributed to several factors, such as uplift of the Tibetan Plateau, retreat of the Paratethys Sea, and global cooling related to polar ice volume increment. However, the fundamental forcing factors remain enigmatic due to the absence of long and continuous climate records and sensitive indicators. Here we reanalyzed the published grain-size record of Sikouzi fine sediments in the western Chinese Loess Plateau through end-member (EM) modeling. The results indicate that EM 2 with grain-size peaks between 10–100 μm decreased in content from 20.1 to 17 Ma and stepwise increased from 17 to 0.07 Ma during the following six stages (17–15 Ma, 15–12 Ma, 12–8 Ma, 8–6 Ma, 6–4 Ma and 4–0 Ma). Such varying trends can be successively correlated in seven stages with the integrated benthic δ18O record, implying that global warming weakened the EAWM from 20.1 to 17 Ma and global cooling has stepwise strengthened the EAWM since 17 Ma. Therefore, we conclude that global temperature change played a major role on the evolution of EAWM during the Neogene period. By contrast, Late Cenozoic palaeogeographic reorganization caused by uplift of the Tibetan Plateau and retreat of the Paratethys Sea contributed less to the evolutionary evolution of EAWM. Spectral analysis of the EM 2 data first provided direct evidence of orbitally influenced deposition in the study area and thus the EAWM variations during the Neogene period. The 100-kyr period became weak since ~10 Ma, possibly due to the decrease in sensitivity of a more stable, continental-scale ice sheet in Antarctica to local insolation forcing, deserving further investigation. [ABSTRACT FROM AUTHOR]

The long-ranging, plug-shaped ichnofossil Conostichus, attributed to solitary polypoid cnidarians, is most commonly described in the Paleozoic from fine-grained siliciclastic sediments, with few descriptions from carbonate settings. The few described examples of putative Conostichus preserved in carbonate sedimentary rocks of Paleozoic age are essentially conical masses lacking recognizable external radial or longitudinal structures. Herein, we describe the occurrence of well-preserved examples of this ichnogenus within middle Silurian (Wenlock: Sheinwoodian) carbonate sedimentary rocks of the Massie Formation from southeastern Indiana, USA. These specimens represent isolated apical discs of Conostichus with prominent radiating physal impressions displaying duodecimal symmetry. Interestingly, well-preserved specimens co-occur with relatively poorly preserved ('typical carbonate') specimens. The factors responsible for this unusual taphonomic state are unclear, but the most likely explanation is that exceptionally preserved specimens represent burrows that were somehow infilled, at least in their apical terminations, with fine-grained carbonate sediment, enhancing preservational fidelity. In contrast, other burrows had their apical regions passively filled with larger carbonate particles that could not preserve fine details. This occurrence indicates that early Paleozoic carbonate sediments are capable of preserving Conostichus, and potentially other ichnofossils, in similar modes to later Paleozoic siliciclastic deposits. [ABSTRACT FROM AUTHOR]

We reconstruct the environmental evolution of the East China Sea in the past 14 kyr based on glycerol dialkyl glycerol tetraethers (GDGTs) in a sediment core from the subaqueous Yangtze River Delta. Two primary phases are recognized. Phase I (13.8-8 cal kyr BP) reflects a predominantly continental influence, showing distinctly higher concentrations of branched GDGTs (averaged 143 ng/g dry sediment weight, dsw) than isoprenoid GDGTs (averaged 36 ng/g dsw), high BIT index (branched vs. isoprenoid tetraethers) values (>0.78) and a fluctuating GDGT-0/crenarchaeol ratio ( R, varied from 0.52 to 3.81). Within this interval, temporal increases of terrestrial and marine influence are attributed to Younger Dryas (YD) (ca. 12.9-12.2 cal kyr BP) cold event and melt-water pulse (MWP) -1B (11.5-11.1 cal kyr BP), respectively. The prominent transition from 8 to 7.9 cal kyr BP shows a sharp decrease in BIT index value (<0.4) and increase in crenarchaeol, which marks the beginning of phase II. Afterwards, the proxies remain relatively constant, which indicates that phase II (7.9 cal kyr BP-present) is a shelf sedimentary environment with high stand of sea level. Overall, the BIT index in our record serves as a good marker for terrestrial influence at the site, and likely reflects the flooding history of the region. The TEX (TetraEther Index of tetraethers consisting of 86 carbons) proxy is not applicable in phase I because of an excess terrestrial influence; but it seems to be valid for revealing the annual SST in phase II (21.6±0.9°C, n=49). In contrast, the MBT'/CBT (Methylation of Branched Tetraethers and Cyclization of Branched Tetraethers) proxy appears to faithfully record the annual mean air temperature (MAT) (14.3±0.63°C, n=68) and presents an integrated signal over the middle and lower Yangtze River drainage basin. [ABSTRACT FROM AUTHOR]

Hydraulic scour is one of the major causes of bridge and embankment failure during typhoon-induced or monsoon-induced floods in steep intermittent rivers in Taiwan. In this study, field data for sediment load and riverbed scour, measured in gravel-bed and sand-bed reaches between 2003 and 2013 are analyzed to determine their differences under nonequilibrium sediment-transport conditions. The riverbed scouring potential was extremely high during the fast-rising stage of a large flood in the bimodal gravel-bed reach. By contrast, the unimodal sand-bed reach with a higher suspended load typically demonstrated a lower scouring rate, although it was still higher than that of a perennial river. Existing bridge-scour formulas suitable for intermittent rivers were examined by separating short-term general scour and localized scour. A maximum general scour-depth formula is developed in this study for use as a potential tool for emergency evacuations and bridge closure purposes. [ABSTRACT FROM AUTHOR]

Many riverine systems have been disconnected from their receiving basins by flood-protection levees and other engineered systems. Reconnecting these alluvial rivers with their receiving basins is a viable option to nourish and sustain existing coastal wetland systems as well as to build new land. This sediment nourishment can be accomplished through direct dredging and placement or through sediment diversions. Efficient design of sediment diversions is important to maximize the land building potential. This study's objective is to quantitatively identify key design attributes of sediment diversions, influencing their ability to capture sediment. The outfall channel alignment angle (ϕ), intake invert elevation, and diversion size are hypothesized as key parameters. The analysis is limited to sediment grain sizes larger than 63 µm and has been performed using a validated three-dimensional numerical model. A time integrated sediment-water ratio was used as an indicator to reflect efficiency of sediment capture. Analyses indicate ϕ has minor impact on total diverted sediment load and limited to the medium sand (M) fractions (250-500 µm) compared to the fine (125-250 µm) and very fine (63-125 µm) size classes. The sediment water ratio increases as intake invert elevation is deepened to a certain limit, then it plateaus around yInv=yBar ~ 0.75, implying that deeper invert beyond that limit may not be beneficial. The analysis also shows that the sediment water ratio sharply increases up to a water discharge extraction ratio of 0.1 as the size of the diversion is increased, and plateaus around 0.2. [ABSTRACT FROM AUTHOR]

Hybrid event beds (HEBs) are a type of deep-water sediment gravity flow deposit that generally comprise a basal clean sandstone overlain by a variety of muddier and less-permeable sandy facies. They are thought to be emplaced by combinations of turbidity currents, transitional flows and debris flows, all as part of the same transport event. To date, a number of studies have highlighted the common presence of HEBs mainly in the outer and marginal parts of deep-water systems where they replace beds composed dominantly of clean sand up-dip and/or axially over scales of km to 10 s km. In addition to these broad patterns, important yet poorly understood short-length facies changes (over metres to 100 s m) occur, modifying the overall texture and reservoir characteristics at or beneath typical spacing of production wells. The nature and origin of the short length-scale transitions is here addressed in four well-exposed HEB-prone outcrops: the Cretaceous-Paleocene Gottero Sandstone and the Miocene Cilento Flysch, both in Italy, the Carboniferous Mam Tor Sandstone in northern England, and the Carboniferous basal Ross Sandstone Formation, Western Ireland. A series of detailed correlation panels show marked lateral variations in internal bed make-up for most of the hybrid event beds studied. This variability typically involves lateral changes in the proportions of the cleaner basal sandstone and the overlying muddy sandstone division that occur without substantial change in the overall event bed thickness. The variability is inferred to reflect the complex fingering between the up-dip sandstone-dominated part of the event bed and the down-dip linked debrite due to internal erosion (ploughing) of the debrite into the basal clean sand. Where the upper part of the bed is dominated by large mudstone rafts, these may have foundered into liquefied sand and been injected and partly fragmented by the sand intrusions. The variable thickness and continuity of the basal clean sandstones have important implications for reservoir characterisation; significant variability in bed character at interwell scale can be anticipated. Rugose contacts between the intra-bed facies divisions may impact on drainage and sweep efficiency during hydrocarbon production. [ABSTRACT FROM AUTHOR]

The internal structure of one of the common fold structures in the western margin of the South Caspian Basin (SCB) has been characterized in 3D using a depth-migrated seismic cube in offshore Azerbaijan. The fold corresponds to a NNW-SSE anticline with a basinward vergence; i.e., eastwards, because in this direction of the margin the SCB is floored by a probable oceanic crust. The anticline has two culminations cut by mud-diapirs and is bounded by two parallel rim synclines with contrasting sedimentary thickness. This anticline deforms congruently the thick Productive Series (PS; Messinian to Late Pliocene), whereas the most recent sequences (<3.1 Ma; e.g., Akchagyl and Apsheron units) onlap or thin towards the fold crest. We reconstruct the existence of two episodes of folding. During deposition of the uppermost PS sequences (ca. 3.5–3.4 to 3.1 Ma), fold uplift initiated with a significantly lower rate than sedimentation. During this epoch, folding was accompanied by basin tilting and by faulting in a basinward normal fault with a limited right lateral, strike-slip component. Motion along this fault zone promoted the downdip flow of a weak layer formed by fluid- and mud-rich sediments (Maykop Formation), which also migrated along strike to build-up the growing anticline. Henceforth, fold growth accelerated and sedimentary units like the Akchagyl (3.1–1.7 Ma) were deposited preferentially in the subsiding flanks. Seafloor upwarping due to folding conditioned the sediment transport, and large deltas adapted their prograding pattern to the growing anticline crest. This structure resembles a detachment fold with a leading, East-vergent forelimb. Nevertheless, the occurrence of progressive tilting accompanying sedimentation and folding, or the mud inflation of the fold core by deep flow parallel to the anticline axis, make this example in the SCB a special example of this fold type. [ABSTRACT FROM AUTHOR]

The article focuses on limited capacity to retain phosphorus in the Baltic proper (BP) offshore sediments. Based on calculations using a phosphorus budget model concludes that the phosphorus concentration in the water column of the BP could be reduced by about 70% within 10–15 years if the deep bottoms were oxygenated.