Mud Deposits Research Articles

Studying in vivo and in vitro effects of a novel polyvinyl benzyl chloride-D-glucaro-1, 4-lactonate polymer-coated bile duct stent for anti-biliary mud deposition.

We aim to coat a novel polyvinyl benzyl chloride-D-glucaro-1, 4-lactonate polymer-coated bile duct stent for anti-biliary mud deposition and investigate its in vivo and in vitro impacts. Biliary mud deposition is a leading cause of plastic biliary stent obstruction after its placement. Orally administrated D-glucaro-1, 4-lactonate is a specific competitive inhibitor of β-glucuronidase that causes biliary mud deposition. In this study, the stents coated with polyvinyl benzyl chloride-D-glucaro-1,4-lactonate polymer (PVBC-DGL) were placed in an ex vivo bile duct model perfused with porcine bile and observed every week until completely blocked. Post establishing the model of bile duct stenosis in piglets, stents are observed through endoscopy, hematology, patency time, and pathological changes within 6 months. The 70% PVBC-DGL stents achieved the highest percentage of the inhibitory effect when the drugs were completely released in vitro. Results were obtained from 14 pigs (5: no coating (original), 4: 0% coating, and 5: 70% coating). The overall patency time of the stents was prolonged in all groups; however, the group with 70% coated stents showed a significantly prolonged patency time as compared to no coating (original) and the 0% coating groups in pigs (23.4 ± 1.8 vs 11.2 ± 2.1 w (p = 0.05); 23.4 ± 1.8 vs 10.5 ± 2.5 w (p = 0.05), respectively). The stents with 70% PVBC-DGL better prevent and control the deposition of bile mud and prolong the patency time of stent placement in the subject animals and may be proposed for further clinical trials in patients.

Deicing Road Salts May Contribute to Impairment of Streambeds through Alterations to Sedimentation Processes

Deicing road salts have been increasingly used in the United States over the past 80 years. Previous studies have shown that these salts can have deteriorating effects on freshwater organisms. Here, we hypothesize that the introduction of road salts to streamwater can also boost aggregation of mud particles suspended in the water column. Such aggregation, also known as flocculation, enhances deposition rates and may lead to increased accumulation of fine sediment on streambeds, thereby contributing to the degradation of benthic ecosystems. In this laboratory study, we specifically investigate how road salts impact (1) the size distribution of mud aggregates in a turbulent water column and (2) the overall settling rate of the mud. The results showed that adding road salts to water samples collected from a stream in southwest Virginia, USA changed the distribution of suspended particle sizes. The addition of salt led to more of the mud existing in large flocs and an overall increase in average size by about 40%. As a result, the settling rate of the mud increased relative to the suspensions without salt. Our results suggest that potential negative effects of road salts on mud deposition should be investigated further.

Neglected role of continental circulation in cross-shelf sediment transport: Implications for paleoclimate reconstructions

Coastal currents play a key role in regulating alongshore sediment transport, and their relationships with winter storms (burst of the East Asian winter monsoon) and formation of the coastal mud deposits on the eastern China shelf have been established, based on which the evolution of the East Asian winter monsoon has been widely explored. Unlike that of coastal deposits, the formation of offshore deposits on the eastern China shelf is very complex and highly debated, leading to enormous challenges on paleoclimate reconstructions based on these deposits. In this study, cross-front sediment transport under a variable Yellow Sea Warm Current (YSWC) was explored using remote sensing imagery and sedimentary records (seismic profile and sediment grain size) from the North Yellow Sea (NYS). The results indicate that, although the offshore mud deposit in the western NYS is formed by winter storms through triggering cross-front transport of coastal sediment around the Shandong Peninsula, the winter storm signal was completely obscured by that of the YSWC, which might determine the flux of cross-front sediment transport on a millennial scale. The 1500 y sub-orbital climate variability cycle could also be observed in distal muds after 2.8 ka. By comparing the sediment composition within the same mud deposit or between adjacent mud deposits in the NYS, we found that the response of cross-front sediment transport to the YSWC varied spatially, which may be a reason for discrepancies observed in previous winter monsoon reconstructions on the eastern China shelf. Therefore, as indicated by this study, offshore deposits on the eastern China shelf are not suitable for inversions of the winter monsoon. In addition, mud deposits on the eastern China shelf are also dramatically affected by other dynamic factors, including typhoons and river flooding; thus, deeply exploring the dynamic characteristics and formation mechanism of these deposits are prerequisites for paleoclimate reconstruction.

A simple and green preparation of red mud-coated membrane for efficient separation of oil-in-water emulsions

This study presented a novel, low-cost and environmentally-friendly underwater superoleophobic membrane for influential separation of oil-in-water emulsions. The membrane was prepared by single-step deposition of waste red mud with sodium alginate on the nitrocellulose support through a vacuum pumping. The red mud-coated membrane had a superamphiphilic characteristic in air, whereas it demonstrated an underwater superoleophobic feature with contact angle values above 159( ± 2)°. The prepared membranes with different amount of red mud showed effective separation performance having rejection and flux values greater than (98.5% and 945 L/m2 h; 99.1% and 1033 L/m2 h; 93.7% and 1186 L/m2 h; 99.8% and 1224 L/m2 h; 99.9% and 1028 L/m2 h) for emulsions of various oils and solvents (diesel, mineral oil, toluene, kerosene and petroleum ether)-in-water, respectively. The oil rejection and permeate flux remained stable at the end of 5 cycles of the emulsion separation and also in the corrosive solutions, including NaOH, HCl and NaCl at 0.5 M of each one. Consequently, the usage of waste red mud in the preparation of underwater superoleophobic membrane through the suggested way can be offered as economical, practical and environmentally benign option for both implementing the efficient separation of oil-in-water emulsions and reuse of the industrial by-products.

Fluid mud dynamics in a tide-dominated estuary: A case study from the Yangtze River

Fluid mud plays an important role in the maintenance of the estuarine turbidity maximum (ETM) and makes a significant contribution to estuarine sediment transport. A seabed tripod system and a shipboard vertical profile were deployed to explore the spatial-temporal variation and mechanism of fluid mud in the ETM of the Yangtze Estuary. The near-bed suspended sediment concentration (SSC) measured by OBS and ABS exceeded 50 kg/m3, confirming the existence of fluid mud. The fluid mud layer varied frequently in thickness during spring and intermediate tides, with a maximum of up to 0.6 m, but maintained stability during neap tides. The thickness rose rapidly during the larger ebb tide in semidiurnal tidal cycles of intermediate tides when the gradient Richardson number (Ri) increased to exceed the critical value of 0.25, and the velocity at 0.2 mab was in the range of 0.5–0.8 m/s. The fluid mud layer transported more than twice as much sediment as the low-concentration upper layer did. Waves and intense currents at the flood phase of tide enhanced vertical mixing within the water column, with Ri being reduced to lower than 0.25 and turbulent kinetic energy (TKE) exceeding 0.01 m2/s2, leading to the breakdown of the fluid mud layer. Sediment stratification damps turbulence close to the seabed and leads to gradual solidification of the bottom fluid mud. Approximately 0.2 m of fluid mud deposit was formed on the seabed within 148 h of the observation period.

Decoupling natural and man-made impacts on the morphologic and sedimentologic changes in the tidal flats, Saemangeum area, west coast of Korea: Implications for benthic ecosystem stability

The morphodynamics of tidal flats responds mainly to the nonlinear interaction between tides and seasonal wave activity. Man-made activities such as reclamation further complicate the morphodynamics by disturbing physical processes acting on the tidal flats. Decoupling the anthropogenic influence from the natural forcing on the tidal-flat morphodynamics is crucial in assessing the adverse effects of man-made activities. Still, it remains a challenge due to inherent difficulties in characterizing spatiotemporal variability of the tidal-flat morphology. A three-year-long field survey using unmanned aviation vehicle (UAV)-assisted photogrammetry, sedimentological and benthic fauna data was conducted on the Shinsi tidal flats near the Saemangeum dike, west coast of Korea, to evaluate the relative significance between natural and anthropogenic influence on the morphologic changes of the tidal flats and benthic community structures. The Shinsi tidal flats exhibited non-seasonal sedimentation patterns and experienced overall erosion despite their sheltered location from the offshore waves. The Saemangeum dike contributed to the sustained erosion by reflecting offshore waves toward the tidal flats during winter to spring. Heavy rainfalls also promoted erosion of the tidal flats in summer. The small-scale embankments complicated the spatial sedimentation trend by protecting tidal flats from offshore waves or promoting erosion with shoaling waves. Notable mud deposition occurred during winter, incompatible with the general hydrodynamic condition, resulting from intensive dredging activity inside and outside the Saemanguem dike. The proliferation of the opportunistic species followed the mud deposition for several months until the enhanced wave activity removed the muddy sediments from the flats. Overall erosion dominance and the temporary occurrence of opportunistic species imply that the Shinsi tidal flats are subject to non-seasonal changes in sedimentology and morphology due to artificial structures and man-made activity, leading to the instability of the benthic communities in the tidal flats.

A Holocene record of floodplain development in the northernmost portion of the Araguaia Belt, southeastern Amazonia

This work aimed to understand the drivers of landscape evolution and floodplain formation in a Precambrian Shield area of southeastern Amazonia. This area evolved during the Quaternary into a denudational system with strong structural control, which produced valley side slopes between the Araguaia Belt (AB) and the topmost Parnaíba basin and narrow floodplains in the lower Vermelho River. These floodplains developed at approximately 11215–11410 cal yr BP with the deposition of muds on the weathered basement rocks of the Couto Magalhães Formation in the Ab (CMF) long before sea-level stabilization on the Amazon coast. The chondrite- and upper continental crust-normalized patterns, along with Al/Ti and La/Th ratios, clearly indicate that muds were derived from the CMF-AB. The strong positive correlation of most of the trace elements and rare earth elements (REEs) with Al and Ti indicates their control by aluminous clay phases and a similar transport process. Overbank flows of the Vermelho River resulted in the deposition and vertical accretion of sands from the fluvial channel over the floodplain, forming discontinuous marginal levees after 4520–4710 cal yr BP. The accreted sands with the predominance of Si, Zr, and Hf and the depletion of most of the major and trace elements are likely associated with quartz enrichment and a strong sorting of heavy minerals, which is also supported by Al2O3/SiO2 vs Fe2O3/SiO2. The tributaries of the lower Vermelho River were active until 3890–4095 cal yr BP, and subsequently, the channel was abandoned as a result of the filling process. At approximately 3440–3560 cal yr BP, the floodplain was influenced by prolonged and severe droughts that fully exposed the muddy deposits and caused the enrichment of Fe-Mnoxyoxide phases. The affinity of most of the potentially toxic elements with Al signifies that these floodplain deposits are a natural record for geochemical background studies.

High-resolution sequence stratigraphy and evolution of the Jeju Strait shelf, Korea, since the Last Glacial Maximum

Sequence analysis of high-resolution seismic profiles and sediment data from the Jeju Strait reveals that the shelf deposits form a depositional sequence consisting of a set of lowstand, transgressive, and highstand systems tracts deposited since the LGM. Six seismic units, each with different seismic facies and geometry, constitute three systems tracts. During the LGM, most of the continental shelf was exposed, resulting in sub-aerial erosion associated with paleo-channel incision, forming incised-channel fill (unit 1). The paleo-river may have supplied abundant terrigenous sediments to the study area around the paleo-river mouth. As the shelf flooded, these sediments were trapped within the paleo-estuary and formed estuarine deposits (unit 2). As transgression continued, the near-surface sediments were reworked and redistributed by shelf erosion, resulting in a thin transgressive sand sheet (unit 3) covering a large area of the shelf. Based on age dates and sea-level curves, a transgressive sand ridge (unit 4) formed during the stillstand or very slow rise period (13.7–11.5 ka BP). The Heuksan mud belt (HMB; unit 5), which is one of the prominent mud deposits located in the western part of the study area, can be divided into two subunits (5a and 5b). The lower part of the HMB (unit 5a) corresponds to shelf mud deposited during transgression. In contrast, the upper part of HMB (unit 5b) consists of recent shelf mud that was deposited during the highstand (after ∼7 cal kyr BP). The Seomjin subaqueous delta (unit 6), which consists exclusively of homogenous mud, was deposited after the sea-level highstand. Unit 6 indicates a transition from proximal to distal facies around the Seomjin River mouth. A single depositional sequence on the Jeju Strait shelf was mainly controlled by the complex interplay between bottom morphology, a varying sediment supply, and high-amplitude (∼130 m) sea-level changes, along with hydrodynamic conditions.

Spatial variation of and the factors influencing the floc size distribution in the North Yellow Sea during the winter season

Suspended particulate matter (SPM) usually exists in the ocean as floc, the behavior of which is believed to be significant for the source to sink sedimentary systems. However, the spatial variation of floc size distributions on the shelf scale is not fully understood. In this study, the SPM floc size distribution and the corresponding hydrological conditions in the North Yellow Sea are delineated to examine the spatial variation of floc size and the influencing factors based on a comprehensive investigation conducted during January 2017. The results indicate that the fine primary particles and microflocs display high volume concentration (Cv) around the tip of the Shandong Peninsula both in surface and bottom layers, while the macroflocs dominate the western North Yellow Sea. The primary particles (<4.48 μm) and microflocs (4.48–219 μm) are mainly inorganic particles, whereas the macroflocs (>219 μm) are dominated by phytoplankton and mucus-bound organic aggregates. The higher Cv of primary particles and microflocs around the tip of Shandong Peninsula mainly results from the resuspension of bottom sediments. Temperature fronts limit the spread of SPM from the coastal area to the offshore area in surface layer, while the bottom sediments tend to cross the temperature front and spread seaward. In the western North Yellow Sea, flocculation is enhanced by plankton which accounts for the dominance of macroflocs, especially in surface layer. The Yellow Sea Warm Current may transport sediments that cross the temperature front in the bottom layer back to the central North Yellow Sea or South Yellow Sea in the winter season. Until the summer season, the deposition of macroflocs may contribute to the formation of mud deposits in the Yellow Sea.

Characteristics and controls on the distribution of sublittoral microbial bioherms in Great Salt Lake, Utah: Implications for understanding microbialite development

AbstractSide‐scan sonar and Compressed High Intensity Radar Pulse mapping of Great Salt Lake, Utah, linked to reprocessing of acoustic data from bathymetric surveys, has enabled the distribution of microbial bioherms to be assessed. Bioherms occupy an estimated area &gt;700 km2 in the south arm and &gt;300 km2 in the north arm. Distributions vary from statistically dispersed to clustered, and in this latter case, are predominantly located on metre‐scale, fault‐controlled topographic highs, with sediment infilling intervening lows between adjacent offsets. Individual bioherms are circular to oblate and range from centimetres to over 2 m in diameter. In some areas, bioherm heights were measured at more than 1.5 m above adjacent substrate. Sublittoral bioherms are made of aragonite, calcite and minor dolomite precipitated due to physico‐chemical, biologically induced and influenced carbonate mineralization processes in association with microbial mats. Bioherm fabrics vary at the millimetre to centimetre‐scale and consist of leiolitic and clotted peloidal micrite‐grade carbonate, sinuous threads of spherulitic fibrous aragonite crystals, laminated micrite boundstone and internal carbonate mud sediment with peloids and ooids. The identification of factors that influence microbial bioherm occurrence and spatial distribution in Great Salt Lake is limited to a set of collinear physical, chemical and biological variables that are confined to a localised closed system, such as salinity, water depth, wave energy, stable substrate and sediment accumulation. Anthropogenic modifications to Great Salt Lake resulting in increased salinity have exceeded the salinity range in which bioherm‐mediating microbial communities can survive, effectively defining an upper limit of salinity for bioherm microbial community viability. The better understanding of the distribution of microbial bioherms has significant implications for managing and protecting the lake ecosystem and may provide insights into the physical and chemical controls that existed during the formation of fossil microbialites in deep time.

3D geo-cellular static virtual outcrop model and its implications for reservoir petro-physical characteristics and heterogeneities

Geostatistical data plays a vibrant role for surface-based reservoir modeling through outcrop analogues, which is used to understand three-dimensional (3D) variability of petrophysical properties. The main purpose of this study is to improvise the surface-based 3D geo-modeling to demonstrate petrophysical characteristics and heterogeneities of Sandakan reservoirs, NW Borneo. We used point cloud data from Light Detection and Ranging (LiDAR) to build high-resolution virtual outcrop modeling (VOM) onto which we mapped 6 different lithofacies. Porosity and permeability of core plugs were measured to determine the average variance of petrophysical properties for each lithofacies. By utilizing the integration of VOMs analogues and petrophysical properties in Petrel™, we demonstrated the distribution and associations of all lithofacies in pseudo wells that have inherent thin beds heterogeneities in 3D geo-cellular model. The results concluded that the heterogeneity of thin beds in lithofacies is dependent on porosity and permeability with input dataset. According to the final model, cross-bedding sandstone (CBS), hummocky cross-stratified sandstone (HCSS) and trough cross-bedding sandstone (TCBS) show good reservoir quality due to high porosity ranging from: 25.6% to 20.4% and, 19.3%–14.5%, and permeability ranging from: 74.03 mD to 66.84 mD and, 64.86 mD to 21.01 mD. In contrast, massive to weak laminae sandstone (MWLS) and bioturbated sandstone (BS) show fair to poor reservoir quality, caused baffling of surrounding mud sediments in the reservoir lithofacies. Results also revealed that LiDAR based VOM with petrophysical properties can significantly reduce the risk and minimize the cost of reservoir modeling in petroleum industry.

Informing the management of multiple stressors on estuarine ecosystems using an expert-based Bayesian Network model

The approach of applying stressor load limits or thresholds to aid estuarine management is being explored in many global case studies. However, there is growing concern regarding the influence of multiple stressors and their cumulative effects on the functioning of estuarine ecosystems due to the considerable uncertainty around stressor interactions. Recognising that empirical data limitations hinder parameterisation of detailed models of estuarine ecosystem responses to multiple stressors (suspended sediment, sediment mud and metal content, and nitrogen inputs), an expert driven Bayesian network (BN) was developed and validated. Overall, trends in estuarine condition predicted by the BN model were well supported by field observations, including results that were markedly higher than random (71–84% concordance), providing confidence in the overall model dynamics. The general BN framework was then applied to a case study estuary to demonstrate the model's utility for informing management decisions. Results indicated that reductions in suspended sediment loading were likely to result in improvements in estuarine condition, which was further improved by reductions in sediment mud and metal content, with an increased likelihood of high abundance of ecological communities relative to baseline conditions. Notably, reductions in suspended sediment were also associated with an increased probability of high nuisance macroalgae and phytoplankton if nutrient loading was not also reduced (associated with increased water column light penetration). Our results highlight that if stressor limit setting is to be implemented, limits must incorporate ecosystem responses to cumulative stressors, consider the present and desired future condition of the estuary of interest, and account for the likelihood of unexpected ecological outcomes regardless of whether the experts (or empirical data) suggest a threshold has or has not been triggered.

A multiproxy reconstruction of the Late Pleistocene-Holocene paleoenvironment: New insights from the NW Black Sea

We provide new data on the Black Sea evolution during the preconnection and reconnection stages with the Mediterranean, based on sedimentology, geochemistry, calcareous nannoplankton and ostracods analysis, in 13 cores placed between 141 m and 1315 m water depths. Unit 1 – The Coccolith Mud, Unit 2 - The Sapropel Mud and Unit 3 – The Lacustrine Lutite, including red-brownish depositional intervals, were identified in all studied deep-water cores. These units are not present in a shallow setting, i.e., above 166.7 m water depth, being replaced by sandy levels and shell debris. The red-brownish layers are interpreted as hyperpycnites, but some of the red successions show turbidite features, especially the ones situated on canyon sides, at a water depth below 600 m. In the oldest intercepted Unit 3 of the Neoeuxinian lake, CaCO3 values are constantly low, but towards the top of this unit they show two distinct peaks, interpreted as signals of Bølling–Allerød and Preboreal interstadials. In between, a significant decrease in CaCO3 values, linked to the setting of the Younger Dryas, is coincident in the deep cores with diatom blooms and high frequency of ostracods related to cooler waters. The scarce but continuous occurrence of Emiliania huxleyi nannoplankton species from the top of Unit 3 indicates that the salinity was at least 10–11‰ prior the Sapropel Mud deposition and increase at a least 17‰ within the lower part of Unit. 2. In the same interval, the Ponto-Caspian ostracods are still present. The Mediterranean ostracods consistently occur from the top of Unit 2, when bottom water salinity reached values for allowing their survival. The first bloom of E. huxleyi is placed at the base of Unit 2, where coccolith laminae occur, while the second bloom is placed in Unit 1 that contains exclusively Mediterranean ostracods and consistent assemblages of benthonic foraminifers, similar with the ones present today.

Deformation-enhanced diagenesis and bacterial proliferation in the Nankai accretionary prism

Abstract. Understanding diagenetic reactions in accreted sediments is critical for establishing the balance of fluid sources and sinks in accretionary prisms, which is in turn important for assessing the fluid pressure field and the ability for faults to host seismic slip. For this reason, we studied diagenetic reactions in deformation bands (shear zones and veins) within deep mud sediments from the Nankai accretionary prism (SW Japan) drilled at site C0001 during IODP Expedition 315, by means of microscopic observation, X-ray diffraction, and major- and trace-element analyses. Deformation bands are not only more compacted than the host sediment but are also enriched in framboidal pyrite, as observed under microscopy and confirmed by chalcophile-element enrichments (Fe, S, Cu, As, Sb, Pb). In tandem, one shear zone sample displays a destabilization of smectite or illite–smectite mixed layers and a slight crystallization of illite relative to its sediment matrix, and another sample shows correlated increases in B and Li in shear zones and veins compared to the host sediment, both effects suggesting a transformation of smectite into illite in deformation bands. The two diagenetic reactions of sulfide precipitation and smectite-to-illite transformation are explained by a combined action of sulfate-reducing and methanogen bacteria, which strongly suggests an increased activity of anaerobic microbial communities localized in deformation bands. This local bacterial proliferation was possibly enhanced by the liberation of hydrogen from strained phyllosilicates. We suggest that the proliferation of anoxic bacteria, boosted by deformation, may contribute to the pore water freshening observed at depth in accretionary prisms. Deformation-enhanced metabolic reactions may also explain the illitization observed in major faults of accretionary prisms. Care is therefore needed before interpreting illitization, and other diagenetic reactions as well, as evidence of shear heating, as these might be biogenic instead of thermogenic.

Influence of Sediment Cycling on the Rare-Earth Element Geochemistry of Fluvial Deposits (Caculuvar–Mucope, Cunene River Basin, Angola)

The rare-earth element (REE) geochemistry of sedimentary deposits has been used in provenance investigations despite the transformation that this group of elements may suffer during a depositional cycle. In the present investigation, we used the geochemistry and XRD mineralogy of a set of sand and mud fluvial deposits to evaluate the ability of REE parameters in provenance tracing, and the changes in REE geochemistry associated with weathering and sorting. The analyzed deposits were generated in a subtropical drainage basin where mafic and felsic units are evenly represented, and these crystalline rocks are covered by sedimentary successions in a wide portion of the basin. A few element ratios appear to hold robust information about primary sources (Eu/Y, Eu/Eu*, LaN/YbN, LaN/SmN, and GdN/YbN), and the provenance signal is best preserved in sand than in mud deposits. Sediment cycles, however, change the REE geochemistry, affecting mud and sand deposits differently. They are responsible for significant REE depletion through quartz dilution in sands and may promote discernible changes in REE patterns in muds (e.g., increase in Ce content and some light REE depletion relative to heavy REE).

Kajian Hidro-Oseanografi Untuk Rehabilitasi Suaka Margasatwa Muara Angke – Jakarta Utara

Muara Angke Wildlife Reserve (MAWR) is the smallest natural reserve area in Indonesia with a wetland ecosystem type, dominated by open swamp and mangroves, and greatly influenced by freshwater from the Angke River. Although small, this region plays an important role in protecting biodiversity, especially for mangrove ecosystems in Jakarta. However, this area has suffered severe degradation because of river pollution and decreasing salinity so that rehabilitation efforts carried out to maintain the presence of mangrove ecosystems. We asses the hydro oceanographic aspects, i.e. tidal conditions, sedimentation and bathymetry by conducting field survey and modeling. Based on the results, there is 0.35 m increase in the water level compare to previous period. The value of Formzhal 2.47 is obtained which indicates the mixed tide prevailing diurnal type, mainly because of the influence of the river, although sometimes their mixed tides with very different heights and periods. The tidal mounts in Muara Angke based on the Admiralty method are 0.94 meters. Then, from the results of the sediment test, it was found the type of mud sediment with a value of TSS between 23 mg/l - 74 mg/l. The result of this study is that the sustainability of the mangrove ecosystem in Muara Angke Wildlife Reserve depends on these three aspects. There needs to be mitigation efforts to reduce sedimentation and overcome freshwater immersion from rivers so that mangrove rehabilitation in this region can be successful.

Experimental analysis of natural organic matter controls on nitrogen reduction during bank storage

Particulate organic carbon (POC) significantly influences nitrogen processes in riparian zones. However, the role of different types of natural organic matter (e.g., plant leaves and mud deposits) in nitrate reduction during the hydraulically driven mixing between rivers and groundwater within bank storage (BS) is not well known. Here, we used laboratory columns filled with 30 cm of riparian soil and buried with POC of varying quantity and quality (leaf litter, mud deposit, a mixture of both and a sediment control) on the soil surface in the column to investigate the effects of POC addition on nitrate reduction in low-permeable media. Pore waters were collected and measured periodically to compare the physicochemical differences among these treatments over time during scenarios of downward and upward flow. The leaf litter treatment had a larger amount of POC and higher reactivity, driving pore water to be in suboxic conditions with lower Eh and pH values. Nitrate reduction occurred immediately with downward surface water, and NO3− was removed in the POC buried layer. Due to the low POC content and low reactivity of the carbon source in the mud deposit, denitrification primarily occurred in the deeper sediment during the downwelling stage, as well as when groundwater returned to the POC buried layer with longer travel times. Both POC quantity and POC quality had strong effects on nitrate reduction. Our results suggested that the leaf litter treatment was preferential for nitrate reduction over the mud deposit treatment, with a higher NO3− reduction rate and less NH4+ accumulation during the complete BS process.

Fluvial-Tidal to Fluvial-Lacustrine Sedimentation of the Middle Miocene to Pleistocene Mapia Formation, Dogiyai, Papua (Indonesia)

A sedimentological and palynological investigation was carried out on outcropping sedimentary rocks at Dogiyai, Papua, proposed to be named as the Mapia Formation. The age range is from Middle Miocene to Pleistocene. The lower Mapia Formation was deposited at Metroxylon type to Nothofagus emarcida Zone, Middle Miocene to Early Pliocene. It is comprised of three facies associations: tidal channel, tidal point bar, and tidal flat deposits. A tidally dominated fluvially influenced depositional environment is suggested for the deposition of sediments of this unit. The upper Mapia Formation was deposited at Malvacipollis diversus Zone, Garcinia cuspidata type Zone, and Proteacidites sp. Zone, Late Pliocene to Pleistocene. It is comprised of five facies associations: delta front, slump, debrite, turbidite, and lacustrine mud deposits. A non-channelized deep-lacustrine slump and debris-flow dominated depositional environment is suggested for the deposition of sediments of this unit. The lower Mapia Formation was deposited as synorogenic clastic sediments at the beginning of Central Range orogeny event while the upper Mapia Formation was deposited in the piggyback basin at the major uplift event.

Study Of Organic Component Of Georgian Therapeutic Mud “Forfotes” By Infrared Spectroscopy

Therapeutic mud (peloide) is among such valuable objects of the nature which is widely used in medical, cosmetic and resort-sanatorium spheres. The intensive development of resort and non-resort peloidotherapy requires, on one side, the significant amount of therapeutic muds and, on the other hand the possibility of the production of mentioned muds in industrial scale which will allow the local and foreign inhabitants the use of the briquettes, granules, massage creams and handkerchiefs manufactured on the basis of peloides. For this reason the detailed study of Georgian mud deposit and of its unassimilated mud (name-forfotes) became necessary from therapeutic as well as from physical-chemical viewpoint. The goal of our research involved the physical-chemical investigation of organic and inorganic composition of unused peloides (forfotes) which provides the research by infrared spectroscopy. As a result of the research of the peloides (forfotes) by infrared spectroscopy a number of absorption spectra was revealed which is indicative of the presence of organic compounds of various classes in large quantities. Many of them are repeated in all spectra but by various intensity. Among them are the absorption bands by maxima (3617.98 cm -1 , 3417.41 cm -1 , 2923.70 cm -1 , 2854.27 cm -1 , 2723.13 cm -1 , 1797.42 cm -1 , 1636.42 cm -1 , 1457.99 cm -1 , 1373.14cm -1 , 1018.28 cm -1 , 779.14 cm -1 , 722.82 cm -1 ). But there are the bands which are characteristic of each sample. From the viewpoint of organic compounds in forfotes muds the absorption bands are sufficiently expressed the sections of infrared specter: 3700-3000 cm -1 , 3550-2700 cm -1 , 2000-700 cm -1 which confirms the presence of alcohols (primary, secondary, tertiary), phenols hydrocarbons.

Depositional control on carbon and sulfur preservation onshore and offshore the Oujiang Estuary: Implications for the C/S ratio as a salinity indicator

Carbon and sulfur preserved in estuary and shelf sediments play a critical role in controlling sediment diagenesis related to the global biogeochemical cycle. Their ratio (C/S = 2.8) in mud sediments has been widely used to distinguish freshwater from marine environments; however, this ratio can be influenced by depositional evolution, physical reworking, and other sedimentological parameters. We present a new C/S ratio data set from surface sediments of five rivers (Aojiang, Feiyunjiang, Jiaojiang, Oujiang, and Qiantangjiang Rivers), as well as core sediments offshore of the Oujiang Estuary (core EC2005, 60 m), to discuss how the evolution of the depositional environment influenced carbon and sulfur preservation since the last deglaciation. To this aim, we measured the contents of total organic carbon (TOC), total sulfur (TS), and carbonate in the collected samples. Our results demonstrate that a C/S ratio of 2.8 can effectively separate freshwater environments (river sediments and core sediments deposited before 13.1 ka), suggesting the initial impact of sulfate-enriched seawater on carbon and sulfur perseveration at ~13.1 ka. However, the TS content is independent of the TOC content after 13.1 ka, implying that pyrite sulfur is derived not only from organoclastic sulfate reduction (OSR) but also from sulfate-driven anaerobic oxidation of methane (AOM) under anoxic diagenetic conditions. In the shallowest core section (shallower than 5 m; < 1.5 ka), the C/S ratios gradually increase from 1 to 2.8, which corresponds to an interval with sulfide reoxidation under suboxic conditions caused by strong physical reworking. When the sediment is buried to a certain depth (deeper than 5 m; > 1.5 ka), a high sedimentation rate is conducive to an AOM reaction, resulting in the generation of a large amount of pyrite and finally causing the minimum value of the C/S ratio to be approximately 1. However, during the transitional period of 13.1–11.0 ka, sediments deposited in the tidal environment show overlap with those deposited in the marine shelf environment, and C/S ratios decrease from >10 to ~1. In addition, we propose that C/S and C/N ratios could be combined to reveal the depositional evolution from terrestrial to marine environments, which is sensitive to sea level and climatic changes. Therefore, our new findings suggest that the sedimentation process can modulate the diagenetic path of mud sediments (e.g., OSR versus AOM), and geochemical indicators of environmental evolution should be carefully used in combination with sedimentological parameters in shallow depositional environments.