Characteristics Of Bottom Sediments Research Articles

Understanding sedimentary dynamics and bottom sediment characteristics in Bons Sinais Estuary – Mozambique: Insights from statistical analysis and Pejrup diagram

This article addresses the Bons Sinais Estuary sedimentary dynamics and bottom sediment characterization and its implication to pollution, based on bottom sediment grain size and statistical parameters. There were collected 15 bottom sediment samples with a Van veen sampler, which were further analysed by sieve and pipette methods. Sand was the most dominant textural class (51%), followed by silt (25%) and clay (24%). The sedimentary dynamics have varied from moderate to high. Both size of sediments and Pejrup diagram suggests that the hydrodynamics of this Estuary is high. Although the percentage of coarse sediments is higher, the estuary is susceptible to pollution, as the amount of thinner sediments is considerable regarding the values of skewness. These results may be useful to environmental management actions including pollutants tracking.

Assessment of chemical characteristics of bottom sediments of Zobe Dam Reservoir, Katsina State, Nigeria

Zobe Dam is one of the silted dams in Nigeria. It is located in the Dustin-ma area in Katsina State northwestern Nigeria. The bottom reservoir sediments of the dam were sampled during the bathymetric studies of the reservoir. The objectives are to: determine the status of mineral elements and their distribution; measure the anomalous elemental concentration, as a tool in search for solid mineral deposits; and determine the usefulness of such sediments when dredged out. A total of 15 samples were obtained and analysed at Federal Steel Council laboratory in Kaduna using a Scanning Electron Microscope which was then transferred electronically to EDX that revealed the elemental constituents of the samples in mg/kg. A total of 27 elements were examined, the order of enrichment is Si > Fe > Al > Hg> K > Pb > Ti > Ca > Cd….All the elements were several times greater than the world's mean crustal abundance. The preponderance of these elements could be attributed to the contamination from artisanal mining of polymetallic mineral associations in Jibia, Dandire, Mallam Tanko Kafur, Dutsin-Ma and other areas within the State; as well as the anthropogenic factors like organic fertilizer application by farmers. It is recommended that the erosion of sand into the dam be checked through the planting of trees and other environmental conservation practices.

Echo-characterization of the Sloggett Canyon and the interfluve with Valentín Canyon, Tierra del Fuego Continental Margin, Argentina

Our recent echo-character analysis of the Tierra del Fuego Continental Margin, focusing on Sloggett Canyon and the interfluve with Valentín Canyon, provides insights into contemporary sedimentary processes. Utilizing high-resolution seismic profiles obtained from the R/V Austral in 2017, we categorized sub-bottom echoes into 10 distinct types, shedding light on various processes such as hemipelagic deposition, mass wasting events, glacial influence, and the impact of bottom water masses. By integrating data from the GLORYS12V1 model (1993–2020), CTDs from the World Ocean Database, and sediment samples, we analyze the interaction between bottom currents, seafloor topography, and sediment characteristics. We conclude that the flow of the Subantarctic Water Mass acts as an active transport of coarser sediment from the continental shelf into the canyon, maintaining the Sloggett Canyon's activity, while the flows of the Upper and Lower Circumpolar Water Masses contribute to contourite formation along the eastern canyon flank and the erosion of the lower interfluve, leading to the generation of distinctive longitudinal scours. Additionally, in the continental rise, the interaction of water masses with the seafloor influences the redistribution of the deep-sea fans from the Sloggett and Valentín canyons towards the northeast. This study significantly enhances our understanding of the sedimentary dynamics in this area, establishing the basis of the sedimentary distribution for future interdisciplinary studies and for setting a new baseline in marine protected areas.

Organic matter geochemical characteristics of bottom sediments of the northern Barents Sea as an indicator of hydrocarbon migration from deep source

Group and molecular compositions of organic matter from bottom sediments of the northern sector of the Barents Sea were analysed. The sites where bottom sediments contain organic matter of molecular composition similar to that of oil are identified. Thermally mature hydrocarbon compounds detected in extracts from sediment samples indicates ongoing migration from deeply buried strata and fluid discharge processes on seafloor within the studied areas. Molecular compositions of extracts from bottom sediments were compared with and showed geochemical characteristics similar to some series described for the closest onshore to the study areas. That allows an assumption that the source for migrated hydrocarbons identified in studied bottom sediments can be Mid-Triassic organic-rich claystone intervals which are a part of sedimentary succession of the North Barents deep depression.

Hydrodynamic Characteristics and Sediment Distribution Patterns in Wulan Delta Estuary, Demak, Indonesia

The Wulan Delta, located in Wedung, Demak, was formed due to the sedimentation process of the Wulan and Serang rivers. Sediment transport starts from rivers to the sea; the process carries nutrients and various chemicals derived from agricultural, industrial, or household activities. This study aims to analyze the characteristics of hydrodynamics, suspended sediment, and bottom sediments in the Wulan Delta waters, Demak. Field data were collected in transitional season two (October) 2022. The obtained data were then analyzed in the laboratory at the Faculty of Fisheries and Marine Science. Results showed that the speed of the surface current in the study area ranged from 0 to 0.1 m/s in spring tide conditions with a surface current pattern coming from the direction of Semarang toward Jepara and 0–0.18 m/s in neap tide conditions with a current pattern coming from the direction of Jepara toward Semarang. The Wulan Delta has a sedimentary characteristic dominated by fine silt, which is as much as 82%–98%, with a deposition characteristic dominated by wave energy that causes successful sediment sorting with a sorting index of −2.25 to 2 and strongly asymmetrical to a small size with a skewness curve value of two.

Karakteristik dan Distribusi Spasial Bahan Organik Pada Sedimen Dasar Perairan Teluk Pacitan Jawa Timur

Pacitan Bay is one of the semi-enclosed waters on East Java's south coast. This area is well-known for having a large fishing port as well as a beach tourism area. The dynamics of Pacitan Bay's waters due to the influence of currents, waves, and the input of water masses from the mainland are thought to affect the characteristics of the waters' bottom sediments. The objective of this study was to map the characteristics of bottom sediments and the distribution of organic substance. This research also analyzed the relationship between sediment characteristics and the concentration of organic subtance in the sediment. The sediment's characteristics were determined using granulometric analysis, and the organic matter content was determined using the Loss of Ignition (LOI) method. The analysis results show that sandy substrates dominate the bottom sediments of Pacitan Bay by an average of 82.22%. The distribution of sandy substrate dominates the bay's north and west. Distance from the shoreline has a significant effect on organic subtance distribution (One Way ANOVA, F = 6.05; p 0.05). The organic matter content of sediments dominated by sand is lower (R2 = 0.76) compared to substrates with softer grain size (silt or mud) and tighter pores, making organic matter efficient to precipitate.

Mineralogical and geochemical characteristics of bottom sediments of saline lakes in Transbaikalia

The results of the research on the water mineralization, the mineral composition, ash content, and organic matter content of bottom sediments of stagnant saline lakes in Southeastern Transbaikalia are presented. It has been established that various ratios of feldspar, quartz, hydroxyl compounds, and carbonate minerals are universally found in the sediments. Sediments on the bottom contain a small amount of organic matter, which classifies them as highly siliceous, consisting mainly of sand and clay minerals. Changes in the mineralogical and geochemical characteristics of bottom sediments at different depths indicate changes in the hydrological regime of the studied lakes and water mineralization in these lakes over time.

Characteristics of Bottom Sediments of Different Marine Ecosystems of Egyptian coast sides

Characteristics of Bottom Sediments of Different Marine Ecosystems of Egyptian coast sides

Characteristics of Bottom Sediments in the Coastal Areas of the Crimean Peninsula

The aim of this work was to assess the influence of physical, chemical, and hydrochemical factors on the characteristics of bottom sediments in various areas of the shelf of the Crimean Peninsula. The data obtained during the cruises of the RV “Professor Vodianitsky” in the fall of 2018 and summer of 2019 were analyzed. Hydrochemical analyses of the bottom waters were carried out using standard hydrochemical methods. Profiles of dissolved oxygen, hydrogen sulfide, and oxidized and reduced forms of iron in pore waters were obtained, and the geochemical characteristics of bottom sediments were determined. The features of their spatial and vertical distributions were considered. Pelite-aleuritic sediments with inclusions of sandy material and shell detritus prevailed in the coastal zone of the Crimean shelf. The organic carbon content varied from 0.5–0.6% in the gravel–sand sediments of the Kerch pre-strait area to 2.5–2.7% in the northwestern part. The prevalence of suboxic conditions was noted, and the main processes in the sediment upper layer were controlled mainly by reactions involving iron. In some areas of the southern coast of Crimea and the Kerch pre-strait area from the Sea of Azov, the development of anoxic conditions in the surface layer of bottom sediments was recorded.

Assessment and analysis of metal bioaccumulation in freshwater gastropods of urban river habitats, Saint Petersburg (Russia).

The aim of this study was to analyze the content of heavy metals in the shells of freshwater gastropods Viviparus sp.; to evaluate the correlation of the trace element accumulation degree in biological objects, bottom sediments, and water, and to assess the degree of pollution of minor rivers of St. Petersburg, as well as the applicability of the studied biological objects for this. Water samples, sediment samples, and gastropods were collected in July 2019 and August 2020 at seven sampling points located at five rivers in St. Petersburg. Analysis of metals in water samples, water extract from bottom sediments, was carried out with atomic emission spectrometry. Analysis of metals in the shells of molluscs Viviparus sp. carried out with atomic absorption spectrophotometry and atomic emission spectrometry. The data obtained indicate the current contamination of the Neva River Delta with a number of metals, such as Al, Mn, Fe, Cu, and Pb, and indicate a significant accumulative capacity of bottom sediments with Zn, Pb, Ni, Cu, Mn, and Fe. Gastropods showed an ability for intensive bioaccumulation, which depended on the properties of metals, the hydrology of the river, and the characteristics of bottom sediments. It was found that for the studied environmental conditions, Sr, Fe, Cr, and Mn have the best ability to bioaccumulate in gastropod shells.

The impact of climate change and eutrophication on phosphorus forms in sediment: Results from a long-term lake mesocosm experiment

Characteristics of bottom sediments in lake mesocosms 11 years after starting the experiment were studied in order to determine the effects of nutrient loading, temperature increase and vegetation type on concentration and vertical distribution of phosphorus (P) forms. The experimental setup consisted of 24 outdoor flow-through mesocosms with two nutrient treatments – low (L) and high (H) and 3 temperature levels – ambient (T0), heated by 2–4 °C (T1) and 3–6 °C (T2) in four replicates. Thickness of the organic sediment was measured and the sediment analysed for dry weight, organic matter, and P fractions (according to a sequential extraction scheme) and organic P compounds (by 31P nuclear magnetic resonance spectroscopy). Higher nutrient loading led to increased sediment accumulation and higher concentration of total P and most P fractions, except P bound to aluminium and humic matter. The dominant vegetation type covaried with nutrient levels. Vertical gradients in Ca bound P and mobile P in low nutrient mesocosms was perhaps a result of P coprecipitation with calcite on macrophytes and P uptake by roots indicating that in macrophyte-rich lakes, plants can be important modifiers of early P diagenesis. Temperature alone did not significantly affect sediment accumulation rate but the interaction effect between nutrient and temperature treatments was significant. At high nutrient loading, sediment thickness decreased with increasing temperature, but at low nutrient loading, it increased with warming. The effect of warming on sediment composition became obvious only in nutrient enriched mesocosms showing that eutrophication makes shallow lake ecosystems more susceptible to climate change.

Hydrocarbon gas seepage along the Gydratny Fault (Lake Baikal)

The Gydratny Fault, extending in SW-NE over 60 km, is situated in the central basin of Lake Baikal. This fault governs a distribution of hydrocarbon gas discharge zones on the lake bottom, many of them are hydrate-bearing. During the Class@Baikal-2019 expedition gas samples were obtained from bottom sediments along the fault zone, molecular and isotopic properties of the gases were studied. It is concluded that the fault zone is permeable for hydrocarbons and serves as an important fluid flow conduit from deep sources to the surface. The most intensive gas seepage was determined along the central and north-eastern segments of the fault zone where it is associated with the MSU hydrate-bearing structure and the Novosibirsk and Ukhan mud volcanoes. Within these structures the highest concentrations of methane and C2+ components were detected, the heaviest isotopic composition of methane carbon (–57‰ VPDB) were identified and near-surface gas hydrate accumulations were observed. The south-western segment of the fault is characterized by the lowest concentrations of gases in sediments with light carbon isotopic composition of methane (–76‰ VPDB).A dominant gas migration mechanism (advection or diffusion) in the upper part of the basin sedimentary section conditions the registered concentrations of methane and its homologues in sediments and their carbon isotopic composition. Diffusion and dispersion of migrated thermogenic gases and significant portion of microbial methane in seeping gases are characteristic for the areas where the fault is buried under relatively thick modern sediments. Focused gas migration followed by its focused discharge are specific for the areas where the fault propagates to the lake floor and is well-expressed in a bottom relief. Two models of hydrocarbon gases migration to the surface explaining the observed gas-geochemical characteristics of bottom sediments are described and discussed. Obtained results can help in enhancing interpretation of data of gas geochemical prospecting for offshore oil and gas.

ФОНОВАЯ ЭКОЛОГО-ГЕОХИМИЧЕСКАЯ ОЦЕНКА ДОННЫХ ОТЛОЖЕНИЙ ВОДОТОКОВ ДЛЯ ТЕРРИТОРИИ ЗОЛОТОРУДНОГО МЕСТОРОЖДЕНИЯ ВЬЮН (РЕСПУБЛИКА САХА-ЯКУТИЯ)

As you know, quite significant gold resources are concentrated on the territory of the Russian Federation, but despite this, work aimed at expanding the mineral resource base of this most valuable metal, which plays a huge role in the country's economy, is still relevant. The object of this study is the territory of the Vyun gold deposit. The subject of the study is bottom sediments of watercourses in the territory of the Vyun gold ore deposit. The aim of the study is to assess the background ecological, geochemical and mineralogical characteristics of bottom sediments of watercourses in the territory of the Vyun gold deposit at the pre-production stage of its development. The work was carried out within the framework of complex ecological and geochemical studies and was organized in accordance with the methodological approaches and methodological recommendations that are currently relevant today. This article presents the results of studies of bottom sediments of watercourses flowing in the territory of the Vyun field. Elemental analysis of bottom sediment samples from watercourses was carried out by inductively coupled plasma mass spectrometry (ICP-MS).. The mineral composition of the samples was studied by optical microscopy, X-ray diffractometry and scanning electron microscopy. The relevance of research is due to the need to obtain background data on the state of the natural environment of the Vyun field, without which it is impossible to further assess the current ecological and geochemical state of the territory and forecast the environmental consequences of the industrial development of the field. At present, the importance of such work is often underestimated, although it is thanks to the background assessment that it is possible to have an idea of the initial parameters of the state of the territory of mineral deposits. This study has just such a focus and is devoted to assessing the background state of bottom sediments of watercourses in the territory of the Vyun gold deposit (Republic (Sakha-Yakutia))

Investigation of the nature of suspended matter under the influence of the facies-genetic characteristics of bottom sediments

The purpose of this study is to obtain a mathematical model to assess the influence of the facies and genetic characteristics of bottom sediments on the distribution of suspended matter during dredging.The addressed problem is associated with the detrimental effect of bottom sediments during hydraulic works on the ecological state of a water body. An increase in the level of technogenic turbidity leads to redistribution of the thermal conductivity of water masses and corresponding deterioration in the habitat of aquatic organisms. The development of a mathematical model for the distribution of suspended matter is an urgent task, the solution of which will allow us to analyze the area of distribution of each of the facies of bottom sediment during dredging operations.A mathematical model of the distribution of facies of suspended matter during dredging operations based on the finite difference method has been developed. Software for modeling and visual representation of the process of propagation of facies of suspended matter in the water space of the Gorin River during dredging operations has been developed using C# software, Visual Studio software development environment.The scientific novelty of the performed work is a qualitative and quantitative assessment of the distribution of suspended solids during dredging operations under conditions of hydrogeological uncertainty.

Chronology of sedimentation in Colesbukta, Spitsbergen (Svalbard Archipelago): the results of the 2018 expedition

This paper presents results of a study of sedimentation in Colesbukta (Isfjorden, Spitsbergen), a typical example of sedimentation in a shallow bay of the Svalbard Archipelago. We have examined sediment samples from several cores collected in Colesbukta in May 2018. To meet the goals of this study, geomorphological features of the Colesbukta catchment area have been identified and described. The lithological characteristics of bottom sediments from the study area have been described and their spatial and temporal changes analyzed. The chronology of sedimentation has been reconstructed by 210Pb and 137Cs. We have calculated sedimentation rates in Colesbukta and their temporal dynamics over the several latest decades. According to our estimations, the sedimentation rate has increased by 2–4 times compared to the middle of the 20th century and ranges from 0.2 to 0.46 mm/year depending on the individual conditions of sedimentation in each part of the bay. Climatic fluctuations are shown to have a direct impact on sedimentation processes in Colesbukta. We have revealed that on the periphery of the studied area the rate of sedimentation better depends on the temperature regime while in its central part it is rather a result of the amount of atmospheric precipitation.

Chemical and ecological quality of water and bottom sediments in small rivers of Belgorod oblast

Belgorod Oblast has limited water resources. The paper explores the chemical and ecological characteristics of water and bottom sediments in the Oskol River tributaries. In samples of water taken from small rivers, Maximum Allowable Concentrations (MAC) for pollutants was excessive, including suspended matter, ammonium ions, nitrite ions, phosphate ions, BOD5 and mineral elements. A hydrochemical water pollution index (WPI6) ranges from 1.0 to 1.9, which characterizes water bodies in the categories from clean to moderately polluted watercourses. A comparatively high WPI6 index is recorded in summer for the Kotel River – 1.4, for the Belenkaya River – 2.3, which is attributed to a high concentration of ammonium ions, nitrites and phosphates found to be present in the water. This indicates recent pollution and a changing trophic status of the reservoir. The amount of metals in river water exceeds the MAC norms: for iron – 1.7 -6 MAC; for copper – 1.6 - 8 MAC; for manganese – 0.8 - 22 MAC; for zinc – 1.9 - 9.9 MAC. Concentrations of micronutrients are subject to significant seasonal fluctuations. No excess of lead is found to be present in surface waters. In the samples of bottom sediments taken from the Oskol River tributaries, no excess of MAC values is found, except for lead (1.1 - 2.9 MAC), manganese (1.6 - 2.2 MAC), copper (1.2 - 1.6 MAC) and phosphate ions (1.3 - 2.3 MAC). It is obvious that the sources of pollution for small rivers are runoffs from agricultural land, livestock farms and household wastewater of nearby settlements.

Metamorfizatsiya donnykh otlozheniy pri nekontroliruyemom sbrose stochnykh vod v litoral'nuyu zonu Gerakleyskogo poluostrova (Krym)

Based on the data of field research performed in 2015, the authors studied characteristics of bottom sediments in the area of a deepwater sewage collector of “Yuzhnye” Integrated Sewage Treatment Plant and transformation of bottom sediments resulted from a longterm anthropogenic impact. The data were obtained by standard methods of geochemical analysis. It is established that the bottom sediments in the wastewater discharge area of “Yuzhnye” Integrated Sewage Treatment Plant are represented by rudaceous and coarsegrained fractions. These are mineral particles formed both as a result of coastal abrasion and in the process of accumulation and diagenesis (shell rock, detrital sand) of bottom sediments. In terms of their size distribution and chemical composition they differed significantly from the sediments formed under natural conditions. These were mostly unconsolidated water-saturated sediments with low carbonate content, high organic carbon and moisture content and signs (impurities, consistency, odour) characteristic of municipal sewage sludge. It is noted that the accumulation level of anthropogenic organic carbon is comparable to that of organic matter in the bottom sediments of Sevastopol region bays characterized by limited water exchange and subject to long-term anthropogenic pollution. Exceeding the previously established critical organic carbon levels in the soft soils of the Black Sea (Corg ≥ 2.5 %) results in destructive changes in ecosystems: it has a negative impact on benthos sharply changing its structural characteristics (abundance, biomass, total species richness) with restructuring of its dominant species structure.

SEA RANCHING OF Holothuria atra: STOCKING DENSITY AND TIME

Strong market demand and uncontrolled exploitation and/or the inadequate management of fisheries have caused many stocks of sea cucumbers to be overexploited. One suggested effort to overcome this problem is sea ranching. Stocking density is the most important consideration in sea cucumber rearing; therefore, this present work is aimed at elucidating the best stocking density for sea ranching of Holothuria atra. H. atra was taken from the Panjang Island, Jepara waters and reared in bottom cages in Teluk Awur waters, Jepara with a density of 30, 20, or 10 individuals per cage measuring 2 m × 2 m × 1.8 m (with bottom area of 4 m2). Stocking times of H. atra were at the initial time of cage installation, the second and the third months after installation. Bottom sediment characteristics (i.e., chlorophyll a, b, phaeophytin, and total carotene) of the sea cucumber habitat and water quality in the cages were measured monthly during the study. The results showed that growth of H. atra fluctuated; low stocking density yielded a higher weight gain than high stocking density did. The highest weight gain was present in the density of 10 individuals/cage in the second stocking month. The highest survival rate of H. atra was seen in the condition of 30 individuals/cage (93%) at the third stocking month, which means that these sea cucumbers were only reared for three months. The highest mortality occurred at a density of 20 individuals/cage with the survival rate being low (45%) at the first stocking time or in the fifth month of rearing. There was fission evidence among H. atra reared in the cages, resulting in smaller organisms. Among the water quality parameters, the concentration of chlorophyll a, b, phaeophytin, and carotene in the sediment fluctuated according to the time of sea cucumber rearing caused by their feeding and bioturbation. The study results suggested to stock H. atra at low density during the second stocking month to get higher growth.

Stages and staging of the study of the seabed for earthmoving systems

The development and development of minerals and building materials in water areas, the laying of underwater communications, planning and dredging underwater are preceded by detailed surveys of soil massifs. They establish the lithology and genesis of deposits, bottom surface bathymetry, physicomechanical, acoustic and other properties of underwater soils. These studies are mainly subordinated to the tasks of geology. At the same time, for the development of the deep-water part of the World Ocean, it is planned to use soil development and transport equipment. The kinematic parameters of the equipment used for engineering and geological research do not correspond to the kinematics of existing or planned underwater systems. Despite some progress in the development of engineering-geological methods for studying the ocean, there are currently no reliable data on the mechanical properties of bottom sediments in natural occurrence. Practically the only way to identify the strength properties of deep-water soils is the sampling method (tubes, grabs, dredges). Soil characteristics are determined from samples brought to the surface in a shore or ship laboratory.
 One of the specific features of the tests being carried out is the consideration of hydrostatic pressure, the effect of which on three-phase soils is especially large. Therefore, it should be expected that the measurement errors of the characteristics of bottom sediments in atmospheric conditions due to the violation of their structural relationships during ascent from great depths can differ by an order of magnitude or more from the true values ​​of the parameters of the soil environment. Thus, in order to determine the operating conditions and set external loads on underwater digging machines, it is necessary to measure the strength, deformation and other characteristics of bottom soils in natural conditions under hydrostatic pressure. This paper considers the methods and technical means used for deep-sea exploration of the seabed. Particular attention is paid to engineering-geological methods, which make it possible at the stage of detailed exploration to obtain not only predictive estimates of the mineral resources of the World Ocean but also to determine the physical and mechanical properties of bottom sediments, on which deep-sea digging machines will have to work.

Mineral and geochemical characteristics of soils and bottom sediments in the area affected by mining dumps (a case study of the Sibay ore deposit)

The article focuses on the chemical composition of hydrosulfates formed in bottom sediments and soils as a consequence of sulfide minerals oxidation in mining waste rock dumps. An alkaline geochemical barrier formed under the dumps reduces pollution of natural-territorial complexes. High concentrations of Zn up to 1.29%, Cu-0.74%, and Cd-27.3 mg/kg are found in the hydrosulfates formed in the river bottom and in the soils. The percentages of exchangeable copper, zinc and cadmium in their total content are 33%, 28% and 22%, respectively. Metals are actively involved in lateral and radial migration, which is regulated by alkaline and evaporation geochemical barriers. The hydrosulfates’ mineralogical composition was studied using microscopy and thermodynamic modeling. Among the secondary minerals, gypsum and iron oxyhydroxides are of primary importance, and to a lesser extent barite, epsomite, and jarosite. Secondary minerals of Cu and Zn in scattering halos are not found, which indicates the leading role of adsorption processes in their phase transitions.