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1
Warsito, Kevin Wijaya, e Wati Astriningsih Pranoto. "ANALISIS KECEPATAN JATUH SEDIMEN PADA SUNGAI CIBEET, JAWA BARAT". Jurnal Muara Sains, Teknologi, Kedokteran dan Ilmu Kesehatan 5, n. 1 (4 maggio 2021): 45. http://dx.doi.org/10.24912/jmstkik.v5i1.7649.
Testo completoAbstract (sommario):
Cibeet River is one of the branch of the Citarum river in West Java province with a length of 101 km. Cibeet River is one of the rivers supplying water and sediment to the West Tarum irrigation channel or known as the Kalimalang. In this research, the sample used was in the form of mud taken at the Cibeet River Estuary. This research is focused on settling velocity which is a parameter for sedimentation in order to improve numerical modeling and conceptual understanding of sediment dynamics, especially mud. Sediment research is carried out in the Soil Mechanics laboratory and Hydraulics laboratory. Bottom withdrawal tube experiments were carried out using 5 types of salinity and 6 kinds of sediment concentrations. The purpose of the study was to obtain settling velocity and compare laboratory results with the Stokes law approach and compare the relationship between settling velocity with sediment concentration and salinity. The optimum salinity is obtained at 15 ‰, and the optimum sediment concentration at 4700 ppm with an average fall speed of 37,28 mm / s. The results from the laboratory are not in accordance with the Stokes law due to the influence of flocculation from the cohesive nature of the mud sediment, so that using the Stokes law approach cannot calculate the velocity of falling sediment on the mud. Keywords: concentration; salinity; sediment; settling velocity AbstrakSungai Cibeet merupakan salah satu anak sungai dari sungai Citarum di provinsi Jawa Barat dengan panjang 101 km. Sungai Cibeet merupakan salah satu sungai pemasok air dan sedimen ke saluran irigasi Tarum Barat atau dikenal sebagai Kalimalang. Pada penelitian ini, sampel yang digunakan berupa lumpur yang diambil di Muara Sungai Cibeet. Penelitian ini difokuskan pada kecepatan jatuh sedimen yang merupakan parameter untuk sedimentasi demi meningkatkan permodelan numerik dan pemahaman konsep dari dinamika sedimen terutama lumpur. Penelitian ini dilakukan di laboratorium Mekanika Tanah dan laboratorium Hidrolika, memakai bottom withdrawal tube, dilakukan dengan menggunakan 5 macam jenis salinitas dan 6 macam konsentrasi sedimen. Penelitian ini membandingkan antara hasil laboratorium dengan pendekatan yaitu hukum Stokes serta membandingkan hubungan antara konsentrasi sedimen dengan salinitas. Untuk salinitas didapat optimum pada saat 15‰, dan konsentrasi sedimen yang optimum pada saat 4700 ppm dengan kecepatan jatuh rata-rata 37,28 mm/s. Hasil dari laboratorium tidak sesuai dengan pendekatan hukum stokes dikarenakan adanya pengaruh flokulasi dari sifat sedimen lumpur yang kohesif, sehingga menggunakan pendekatan hukum stokes tidak bisa untuk menghitung kecepatan jatuh sedimen pada lumpur.
2
Hamzah, Faisal, Nuryani Widakti e Frida Sidik. "The Growth of Mangroves in Created Wetland in the Porong River, East Java, Indonesia". Journal of Tropical Crop Science 2, n. 1 (1 febbraio 2015): 10–15. http://dx.doi.org/10.29244/jtcs.2.1.10-15.
Testo completoAbstract (sommario):
Mangrove plantation projects have been established in the created mangrove wetland in the mouth of the Porong River, East Java, in parallel with the construction of reclamation area for LUSI mud dumping area. This study was aimed to assess the growth of planted mangrove in a created mangrove wetland in relation to the environmental parameters, which are sediment salinity, sediment fraction, pore water salinity, pH/eH, and total organic matter (TOM) in the sediment. Periodical measurement of mangrove growth Avicennia sp. and the environmental parameters were undertaken in the created wetland and in the mud flats of intact mangrove forest nearby the created wetland as the natural reference in July to November 2012. We found that sediments in the created wetland had different characteristics of sediment fractions, sediment salinity and TOM compared to sediments in the mud flats of intact forests. Sand dominated sediments with low TOM and higher water salinity in the created wetland as compared to those in the mud flats affected growth rate of mangroves in study sites. We suggest that TOM and salinity are important factors that contribute to the growth of mangroves in the Porong River. Keywords: Mangrove, salinity, Porong River, total organic matter.
3
Spears, Bryan M., James E. Saunders, Irvine Davidson e David M. Paterson. "Microalgal sediment biostabilisation along a salinity gradient in the Eden Estuary, Scotland: unravelling a paradox". Marine and Freshwater Research 59, n. 4 (2008): 313. http://dx.doi.org/10.1071/mf07164.
Testo completoAbstract (sommario):
Microalgal biostabilisation of cohesive sediments via the production of extracellular polymeric substances (EPS) has been well documented in intertidal ecosystems and represents a key ecosystem service with respect to the regulation of sediment transport. However, recent ecosystem comparison studies have uncovered a paradox in which sediment stability is commonly observed to be lower in freshwater ecosystems (compared with estuarine ecosystems) even though sediment EPS concentrations and microalgal biomass are high. Using a combination of freshwater and estuarine field and mesocosm techniques, the relative and interactive roles of salinity and the production of EPS (carbohydrate concentration) by benthic microalgae in the mediation of sediment stability in the Eden River catchment (river, mudflat and saltmarsh) were assessed. Sediment stability apparently increased with salinity from river (42.43 N m–2 surface stagnation pressure; salinity 0) to mudflat (98.65 N m–2; salinity 25) to saltmarsh (135.48 N m–2; salinity 46). The opposite trend was observed in sediment chlorophyll a and carbohydrate concentrations, indicating that salinity is the main variable driving sediment stability across the ecosystems under moderate EPS concentrations. Observations from mesocosm experiments highlighted the individual and combined importance of salinity and EPS in biostabilisation, with the largest increase in sediment stability observed following combined additions (25-fold increase compared with the control). The biogeochemical processes responsible, and their role in buffering phosphorus transport across the freshwater–saltwater transitional zone, are discussed.
4
Yatmadi, Denny, Muslim Muin, Ricky L. Tawekal, Heru Nur Alam e Arung Bahari Muslim. "Cohesive Sediment Simulation in Kanal Banjir Barat Using MuSed3D, Non-Orthogonal Boundary Fitted Sediment Transport Model". IOP Conference Series: Earth and Environmental Science 1065, n. 1 (1 luglio 2022): 012014. http://dx.doi.org/10.1088/1755-1315/1065/1/012014.
Testo completoAbstract (sommario):
Abstract Fine-grained cohesive sediments dominate sedimentation in the lowland area. In the Density Induced Current process, where seawater intrusion occurs, the fine-grained cohesive sediment will be easily flocculated by saltwater and settles rapidly. There are complex problems related to sedimentation in the rivers of Jakarta in the downstream area, which is influenced by tides and the dominance of cohesive sediment. Due to the complex process in the estuary, salinity intrusion will affect the settling velocity. And then, the flocculation process, the river’s geometry, will also affect sediment deposition. A proper model is needed to simulate the sedimentation in this area. This study aimed to investigate the distribution of cohesive sedimentation using 3D hydrodynamic and sediment transport model called MuSed 3D. This model will be applied to the Kanal Banjir Barat (KBB) river, Jakarta. The model result shows salinity values in the range of field observations for TSS and salinity. Salinity model present from 1 till 10 ppt and TSS present from 9,8 until 14,2 ppm. This study concludes that the dispersion of sediment cohesive on river and estuary affected by Density Induced Current also depends on salinity and TSS value.
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Tsai, CH, e SC Hwang. "Flocculation of sediment from the Tanshui River estuary". Marine and Freshwater Research 46, n. 1 (1995): 383. http://dx.doi.org/10.1071/mf9950383.
Testo completoAbstract (sommario):
Experiments on the flocculation of fine-grained sediments from the Tanshui River estuary, Taiwan, were carried out. The effects of fluid shear, sediment concentration and salinity on floc growth were investigated. The ranges of these parameters were 12.5 to 400 s-1 for the shear, 50 to 600 mg L-1 for the sediments concentration and 0% to 100% sea water for the salinity. The results showed the following. (1) The time required to reach a steady state ranges from 2 to 44 h and median floc sizes range from 100 to 520 μm. (2) The steady-state median floc size decreases with the increase in sediment concentration. (3) The floc size increases as the shear increases. (4) Increasing the proportion of sea water from 0% to 50% decreases the floc size to one-fourth of that of freshwater flocs, and a further increase in salinity does not decrease floc size significantly. (5) The time required to reach a steady state decreases with the decrease in shear, the increase in sediment concentration and the increase in salinity. (6) The larger the steady-state flocs, the longer they take to form. Comparison of these results with those obtained in similar studies of Lake Erie sediments shows that the flocculation properties of Tanshui sediments are substantially different from those of Lake Erie sediments. Tanshui sediments are much more difficult to aggregate, but once flocs are formed they are larger. The reasons why different types of sediment behave differently should be studied further.
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Yao, Suni. "River water injecting into sea: Movement of sediments in stable stratified flows". Theoretical and Natural Science 34, n. 1 (2 aprile 2024): 8–18. http://dx.doi.org/10.54254/2753-8818/34/20241125.
Testo completoAbstract (sommario):
The study of sediment movement in a stably stratified (each layer is less dense than the one below it) fluid is important for applications such as airborne virus transport, contaminant transport, and sediment settling in river inlets. This project will quantify the effect of sediment-driven instability on the horizontal motion of sediment in a stably stratified fluid. Experiments are designed to analyze this process by adding sediment-rich brine-free water to sediment-free brine, where salinity differences are used to construct stably stratified fluids. The experiments are done with salinity same as salty water with concentration of sediments derived from linear stability analysis. This work provide baseline experiments for sediment settling in a stably stratified fluids for numerical validations in the future.
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Torres-Alvarado, María del Rocío, Teresa Pérez Muñoz e Neivy Betsabet Maldonado-Vela. "Methanogenesis in sediments of a tropical coastal wetland: a culture-dependent method". Revista de Biología Tropical 72, n. 1 (16 aprile 2024): e57126. http://dx.doi.org/10.15517/rev.biol.trop..v72i1.57126.
Testo completoAbstract (sommario):
Introduction: Methanogenic archaea (MA), participate in the anaerobic mineralization of organic matter in mangrove sediments, their activity is related to atmospheric warming due to the production of methane; several environmental variables can influence the presence of MA and methane production in these sediments. Objective: To analyze, through culture-dependent techniques, viable methanogenic archaea (VMA) in the sediments, and the production of methane from acetate in different climatic periods in the mangrove El Morro-La Mancha, Veracruz, Gulf of Mexico. Methods: From May to November 2019, following a salinity transect, sediment samples from El Morro-La Mancha mangrove were collected at three locations, in three different climatic seasons, dry (May), rainy (October) and northern (November) (N = 9). VMA in the sediments was quantified using the Most Probable Number (MPN) technique with acetate and methanol as substrates. The influence of sulfate on methane production was analyzed from acetate in microcosm by gas chromatography and the chemical variables of salinity, pH, Eh, carbohydrates, organic content, and carbonates in the sediments were evaluated. Results: The abundance of VMA was 102 to 108 MPN/g of wet sediment, higher than that reported in other studies, this abundance was higher when methanol (104-108 MPN/g sediment) was used as substrate, compared to acetate (102-105 MPN/g sediment); methane production in the microcosms increased in sulfate-free conditions (29.78-929.75 nmol CH4/month) and in the sediments of the rainy season. Conclusion: The influence of the chemical conditions of the mangrove sediments on the methanogenic dynamics is highlighted, determining that in the rainy season, the decrease in salinity, more electronegative Eh, and the increase in organic fractions favored the methanogenesis. Objetive: To analyze, through culture-dependent techniques, the abundance of MA and the production of methane in different climatic periods in the mangrove El Morro-La Mancha, Veracruz, Gulf of Mexico. Methods: From May to November 2019, following a salinity transect, sediment samples from El Morro-La Mancha mangrove were collected at three sampling locations, in three different climatic seasons, dry (May), rainy (October) and northern (November) (n=9). The methanogenic abundance in the sediments was quantified using the Most Probable Number (MPN) technique with acetate and methanol as substrates; methane production was analyzed from acetate by gas chromatography and the chemical variables of salinity, pH, Eh, carbohydrates, organic content and carbonates in the sediments were evaluated. Results: The abundance of MA was 102 to 108 cells/g of wet sediment, higher to that reported in other studies, this abundance was higher when methanol (104 - 108 cells/g sediment) was used as substrate, compared to acetate (102 - 105 cells/sediment); methane production increased in rains with 13% compared to dry. Conclusion: Highlighted the influence of the chemical conditions of the mangrove sediments on the methanogenic dynamics, determining that in the rainy season, the decrease in salinity, Eh more electronegative and the increase in organic fractions favored both methanogenic abundance as methane production.
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Zhang, Xiaolei, Xin Liu, Haoran Wu, Shuyu Liu, Yu Zhu, Zhengzheng Bi e Zhiheng Xu. "Experimental Study on the Incipient Movement of Muddy Clay under Different Salinity Conditions". Scientific World Journal 2022 (5 settembre 2022): 1–13. http://dx.doi.org/10.1155/2022/5245928.
Testo completoAbstract (sommario):
In order to understand the incipient movement of muddy clay under different salinity conditions, three series of flume tests were performed on incipient movement of muddy clay, including tests on incipient movement of salt-free clay mud under salt water conditions (salt water-salt-free clay mud), incipient movement of salt clay mud under salt water conditions (salt water-salt clay mud), and incipient movement of salt clay mud under freshwater conditions (freshwater-salt clay mud), using a circulating flume, in which the salinity of the water body or cohesive sediment varies from 0 to 40%. Based on the particle image velocimetry system and digital image gray processing technology, the gray curves of water near the clay mud bed surface with the velocity were plotted to quantitatively differentiate the incipient velocity of the sediment for each test. The experimental results showed that the higher the salinity of the water body or cohesive sediments is, the more difficult it is to start moving. There is a logarithmic relationship between the incipient velocity of cohesive sediments and the salinity of the water or cohesive sediments. The incipient velocity increases sharply at a salinity of 0∼10% and slowly at a salinity of 10∼40%. At the same salinity, the incipient velocity of salt clay mud under freshwater conditions is the largest, followed by that of salt clay mud under salt water conditions, while that of salt-free clay mud under salt water conditions is the smallest. In addition, the flow turbulence characteristics were analyzed under the critical conditions of the onset of muddy clay. Ultimately, an empirical formula to calculate the critical incipient velocity of muddy clay is proposed by introducing the salinity. In this study, salinity is included as a reference variable, which expands the research scope of sediment initiation and provides a reference for the study of estuary dynamics.
9
Singare, Pravin U., M. V. A. Ansari e N. N. Dixit. "Assessment of Physico-Chemical Properties of Sediments Collected along the Mahul Creek near Mumbai, India". International Letters of Natural Sciences 16 (maggio 2014): 54–61. http://dx.doi.org/10.18052/www.scipress.com/ilns.16.54.
Testo completoAbstract (sommario):
The present study was performed for the period of one year from January 2013 to December 2013 in order to understand the physico-chemical properties of sediments samples collected along the Mahul Creek of Mumbai. The annual average pH value of the creek sediments was recorded as 5.38. It is feared that such low pH value of sediment might increase the acidity of creek water thereby triggering the heavy metal toxicity which will further reduced survivorship in fish through chronic stress and affect the reproductive partner. The annual average salinity content of the sediment was recorded as 4601.17 ppm. It is important here to note that the high salinity of the sediment may increase the salinity level of creek water which is considered as a major stress factor for most freshwater organisms including crustaceans. The average annual concentration of phosphate in the creek sediment was found to 480.39 ppm. Such high concentration of phosphate in the creek sediments might accelerate the process of eutrophication. From the results it appears that as India moves towards stricter regulation of industrial effluents to control water pollution, greater efforts are required to reduce the risk due to the toxic pollutants which are released into the ecosystems.
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Singare, Pravin U., M. V. A. Ansari e N. N. Dixit. "Assessment of Physico-Chemical Properties of Sediments Collected along the Mahul Creek near Mumbai, India". International Letters of Natural Sciences 16 (30 maggio 2014): 54–61. http://dx.doi.org/10.56431/p-23xkb4.
Testo completoAbstract (sommario):
The present study was performed for the period of one year from January 2013 to December 2013 in order to understand the physico-chemical properties of sediments samples collected along the Mahul Creek of Mumbai. The annual average pH value of the creek sediments was recorded as 5.38. It is feared that such low pH value of sediment might increase the acidity of creek water thereby triggering the heavy metal toxicity which will further reduced survivorship in fish through chronic stress and affect the reproductive partner. The annual average salinity content of the sediment was recorded as 4601.17 ppm. It is important here to note that the high salinity of the sediment may increase the salinity level of creek water which is considered as a major stress factor for most freshwater organisms including crustaceans. The average annual concentration of phosphate in the creek sediment was found to 480.39 ppm. Such high concentration of phosphate in the creek sediments might accelerate the process of eutrophication. From the results it appears that as India moves towards stricter regulation of industrial effluents to control water pollution, greater efforts are required to reduce the risk due to the toxic pollutants which are released into the ecosystems.
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Cao, Wen-Qing, Jun Song e Gui-Peng Yang. "An adsorption and thermodynamic study of ofloxacin on marine sediments". Environmental Chemistry 14, n. 6 (2017): 350. http://dx.doi.org/10.1071/en16188.
Testo completoAbstract (sommario):
Environmental contextOfloxacin, a widely used fluorinated antibiotic, is resistant to biodegradation and hence can accumulate in the environment. A systematic investigation of ofloxacin on marine sediments showed that sediment organic carbon and heterogeneous sites on sediments play important roles in adsorption processes. The results help our understanding of the environmental behaviour and fate of ofloxacin in marine systems. AbstractThe adsorption behaviour of ofloxacin (OFL) on marine sediments treated by different methods was investigated using batch experiments. Three factors (sediment organic carbon content, salinity and temperature) that may affect the adsorption behaviour of OFL were analysed. The equilibrium time for OFL adsorption on marine sediment in natural seawater was ~4–5h. The adsorption of OFL on all sediments with different treatments fitted the Freundlich model well. The adsorption parameter Kf value was in the order of Kf (H2O2 treatment)<Kf (H2O treatment)<Kf (HCl treatment) over the studied concentration range. The adsorption of OFL was influenced not only by the sediment organic carbon content but also by external factors such as salinity of media and temperature. The adsorption was favourably influenced by decreased salinity and temperature of seawater. The adsorption capacity of OFL on marine sediments decreased with an increase of temperature and salinity. The Kf values decreased from 33.73±1.66 to 22.54±1.12(Lkg−1)1/n when the temperature increased from 283 to 313K. The changes in standard Gibbs free energy (ΔG0) and enthalpy (ΔH0) were −6.62±0.34kJmol−1 and −7.58±0.38kJmol−1 respectively, indicating that the adsorption process of OFL was spontaneous and exothermic. The positive value of the entropy change ΔS0 (i.e. 3.38±0.17JK−1mol−1) suggests that the degree of freedom increased during the adsorption process.
12
Zhao, Jun, Liangsheng Zhu, Bo Hong e Jianhua Li. "A Baroclinic Fluid Model and Its Application in Investigating the Salinity Transport Process Within the Sediment–Water Interface in an Idealized Estuary". Journal of Marine Science and Engineering 12, n. 11 (20 novembre 2024): 2107. http://dx.doi.org/10.3390/jmse12112107.
Testo completoAbstract (sommario):
Understanding the salinity transport process around the sediment–water interface is important for water resources management in the upper reach of an estuary. In this study, we developed a baroclinic fluid dynamic model for investigating the flow and salt transport characteristics within the sediment–water interface under tidal forcing. The validation showed robust model performance on the salinity transport within the sediment–water interface. The results revealed that the turbulent kinetic energy, dissipation rate, and kinetic energy production rate exhibited periodic variations within the seabed boundary layer. The thickness of the viscous sublayer and the mean flow showed an inverse relationship. Water and salinity exchange within the sediment–water interface occurred predominantly via turbulent diffusion, with extreme turbulent kinetic energy production rates appearing during the tidal reversal, flood, and ebb stages. The sediment acted as a source of salinity release during ebb tides and a sink for salinity absorption during flood tides. As the sediment depth increased, fluctuations in salinity were weakened. These results clearly illustrated that the sediment layer is important in modulating the salinity transport in the upper reach of an estuary. However, such an important process was usually excluded by previous studies. The model developed in this study can be used as a sediment–water interface module that, coupled with other hydrodynamic models, can evaluate the contributions of the sediment layer to the salinity exchange in coastal water.
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Husband, Brian C., e Michael Hickman. "The frequency and local abundance of Ruppia occidentalis in relation to sediment texture and lake salinity". Canadian Journal of Botany 67, n. 8 (1 agosto 1989): 2444–49. http://dx.doi.org/10.1139/b89-314.
Testo completoAbstract (sommario):
Ruppia occidentalis S. Wats. is a submerged macrophyte often found in saline and subsaline (> 3000 mg ∙ L−1 and 500–3000 mg ∙ L−1 total dissolved solids (TDS), respectively) lakes but rarely in freshwater (< 500 mg ∙ L−1, TDS) in Alberta, Canada. To determine the effect of water salinity on its distribution, we investigated the frequency and local abundance of R. occidentalis in relation to sediment texture within three lakes, having 2165, 1557, and 275 mg ∙ L−1 total dissolved solids. Sediment texture has the largest effect in freshwater and differences among lakes are greatest on the sediment with greatest local abundance. Ruppia occidentalis occurred in 82, 79, and 42%, respectively, of the sites examined within these lakes. This reduction in frequency was associated with a decrease in the diversity of sediment textures in which R. occidentalis occurred. Within the saline lakes, the frequency of R. occidentalis was not dependent on sediment texture. In freshwater, however, R. occidentalis is found primarily on coarse-textured sites. The absence of R. occidentalis from fine-textured sediments, when in freshwater, is not correlated with the abundance of other macrophytes. Local environments associated with coarse sediments, such as low organic content or reduced biotic interactions, are necessary for R. occidentalis to occur in freshwater. However, contrary to the patterns of frequency among sites, local abundance in relation to sediment texture was similar among lakes and least on coarse-textured sediments. Moreover, local abundance was not significantly correlated with lake salinity, except on sandy sites. Therefore, the effects of water salinity on the colonization of new sites, rather than the performance within sites, may be most important in determining the distributional limits of R. occidentalis in central Alberta.
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Nguyen Tran, Thuy Thanh Mai, Thanh An Bui, Thi Son Le e Quynh Huong Pham. "Evaluation of the carbon storage in the sediments in the mangrove ecosystem growing on abandoned salt pan in Can Gio District, Ho Chi Minh City, Vietnam". Research Journal of Chemistry and Environment 27, n. 7 (15 giugno 2023): 65–73. http://dx.doi.org/10.25303/2707rjce065073.
Testo completoAbstract (sommario):
This study aims to evaluate the size of the sedimentary carbon sink in the coupling with environmental conditions in a mangrove planted in an abandoned salt pan in Can Gio Mangrove Biosphere Reserve. Sediment samples were collected at four sites chosen based on their dominant plant species. Sediment temperature, pH, salinity, humidity and wet bulk density were measured in field, while the nutrients (NH4+, PO43-) and organic carbon (Corg) concentrations were determined in the laboratory. The results showed that humidity, salinity and bulk density were strongly correlated with Corg concentrations. The amounts of organic carbon stored in the sediments in the dry and wet season were 380 MgC.ha-1 and 552 MgC.ha-1 respectively. Sediment humidity and salinity were the primary factors governing the size of the sedimentary carbon sink. The concentrations of organic carbon and ammonium were influenced by an allochthonous source entering the study area via the tidal creek network.
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Paudel, Bhanu, Paul A. Montagna, Mark Besonen e Leslie Adams. "Inorganic nitrogen release from sediment slurry of riverine and estuarine ecosystems located at different river regimes". Marine and Freshwater Research 68, n. 7 (2017): 1282. http://dx.doi.org/10.1071/mf16260.
Testo completoAbstract (sommario):
The purpose of the present study was to compare the nature of dissolved inorganic nitrogen (DIN=ammonium (NH4+) and nitrite+nitrate (NO2+3=(NO2–+NO3–)) release from aerobic sediment slurry at two different hydrologic flow regimes. The watershed of the Guadalupe River–Estuary system receives more freshwater inflow than does the watershed of the Nueces River–Estuary system; thus, the Nueces Estuary is more saline than is the Guadalupe Estuary. Sediment samples were collected using cores, analysed for organic matter and grain size, and used to perform laboratory experiments to measure DIN release. During the experiments, DIN concentrations in overlying water were measured for 48h in five different salinity treatments. Ammonium concentrations were higher in the Nueces River and Estuary treatments than in similarly treated samples from the Guadalupe River and Estuary. An increase in NO2+3 concentrations along salinity gradients of the Nueces Estuary treatments indicated favourable condition for nitrification. The Guadalupe River sediments that were not exposed to salinity had an increase in NH4+ concentration at 7.5ppt. The different DIN release among salinity treatments indicated that hydrologic forcing on organic matter deposition and salinity have an important role on the retention and release of inorganic nitrogen at the sediment–water aerobic layers in rivers and estuaries.
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Kulp, T. R., S. Han, C. W. Saltikov, B. D. Lanoil, K. Zargar e R. S. Oremland. "Effects of Imposed Salinity Gradients on Dissimilatory Arsenate Reduction, Sulfate Reduction, and Other Microbial Processes in Sediments from Two California Soda Lakes". Applied and Environmental Microbiology 73, n. 16 (29 giugno 2007): 5130–37. http://dx.doi.org/10.1128/aem.00771-07.
Testo completoAbstract (sommario):
ABSTRACT Salinity effects on microbial community structure and on potential rates of arsenate reduction, arsenite oxidation, sulfate reduction, denitrification, and methanogenesis were examined in sediment slurries from two California soda lakes. We conducted experiments with Mono Lake and Searles Lake sediments over a wide range of salt concentrations (25 to 346 g liter−1). With the exception of sulfate reduction, rates of all processes demonstrated an inverse relationship to total salinity. However, each of these processes persisted at low but detectable rates at salt saturation. Denaturing gradient gel electrophoresis analysis of partial 16S rRNA genes amplified from As(V) reduction slurries revealed that distinct microbial populations grew at low (25 to 50 g liter−1), intermediate (100 to 200 g liter−1), and high (>300 g liter−1) salinity. At intermediate and high salinities, a close relative of a cultivated As-respiring halophile was present. These results suggest that organisms adapted to more dilute conditions can remain viable at high salinity and rapidly repopulate the lake during periods of rising lake level. In contrast to As reduction, sulfate reduction in Mono Lake slurries was undetectable at salt saturation. Furthermore, sulfate reduction was excluded from Searles Lake sediments at any salinity despite the presence of abundant sulfate. Sulfate reduction occurred in Searles Lake sediment slurries only following inoculation with Mono Lake sediment, indicating the absence of sulfate-reducing flora. Experiments with borate-amended Mono Lake slurries suggest that the notably high (0.46 molal) concentration of borate in the Searles Lake brine was responsible for the exclusion of sulfate reducers from that ecosystem.
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Altahaan, Zena, e Daniel Dobslaw. "Assessment of the Impact of War on Concentrations of Pollutants and Heavy Metals and Their Seasonal Variations in Water and Sediments of the Tigris River in Mosul/Iraq". Environments 11, n. 1 (3 gennaio 2024): 10. http://dx.doi.org/10.3390/environments11010010.
Testo completoAbstract (sommario):
The war-related contamination of water and sediment of the Tigris River within the urban area of Mosul leads to seasonally independent exceedances of the WHO limit values for Cd, Pb, Cr, and Ni in water and sediments. Furthermore, exceedances consistently occur for conductivity, PO43−, and SO42−, as well as sporadically for salinity and COD in water samples, and consistently for salinity in sediment samples, highlighting the direct impact of war (ammunition, ignition of sulfur fields), as well as indirect effects (destroyed wastewater infrastructure). Conflict-related emissions from the former conflict zone (S5–S7) are highlighted by the sudden increases in load from S4 to S5, although partially masked by the discharge of highly polluted water from the Khosr River (between S3 and S4). Due to the sorption of sediments and the presumed wind-borne discharge of highly polluted particles into the Tigris River, sediments at S10 on the southern edge of Mosul showed the highest pollutant loads. Significant statistical differences were observed through T-test analyses for E.C., TDS, salinity, COD, PO43−, NO3−, SO42−, Cd, Pb, Zn, Cr, and Ni for water samples, as well as salinity, Cd, Pb, Zn, and Cr for the sediment samples for seasonal comparison. Since the percentage difference of water samples at S4–S7 is smaller than upstream and downstream, contaminant input is not limited to rainwater but also occurs via the year-round infiltration of highly polluted wastewater from the surrounding valleys or suburban areas, as well as presumably polluted groundwater or windblown particulate input.
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Maulina, Dinda Rizky Ayu, Delianis Pringgenies e Dwi Haryanti. "Kandungan Logam Berat Pb dan Cd dalam Sedimen di Pantai Trimulyo dan Pantai Tirang, Semarang". Journal of Marine Research 13, n. 1 (28 dicembre 2023): 20–28. http://dx.doi.org/10.14710/jmr.v13i1.35038.
Testo completoAbstract (sommario):
Kandungan timbal (Pb) dan kadmium (Cd) di sedimen sebagian berasal dari limbah industri yang masuk ke perairan dan terakumulasi di muara sungai. Pantai Trimulyo berada di pesisir Semarang, dekat dengan Kawasan Industri Terboyo yang berpotensi membuang limbah logam berat ke peraian. Pantai Tirang juga berpotensi tercemar limbah logam berat dari industri di Kecamatan Tugu yang masuk ke aliran Sungai Tapak. Penelitian ini bertujuan untuk mengetahui kandungan logam Pb dan Cd pada sedimen di Pantai Trimulyo dan Pantai Tirang. Penelitian dilakukan dengan metode survei eksploratif dan penentuan lokasi pengamatan dengan metode purposive sampling. Sampel sedimen diambil sebanyak 3 kali pengulangan disetiap lokasi dengan sediment core. Sampel sedimen dianalisis di Laboratorium BBTPPI Semarang menggunakan alat Atomic Absorption Spectrophotometer (AAS) untuk menentukan kadar logam Pb dan Cd dalam sedimen. Hasil analisis kandungan logam Pb dalam sedimen menunjukkan bahwa konsentrasi logam berat tertinggi ditemukan di Pantai Tirang sebesar 49,16 mg/kg dan Pantai Trimulyo memiliki kandungan Pb tertinggi 23,78 mg/kg. Hasil analisis kandungan logam Cd dalam sedimen di Pantai Trimulyo dan Pantai Tirang sebesar >0,050 mg/kg. Pengukuran parameter lingkungan (suhu, salinitas, pH, DO, kecepatan arus dan kecerahan perairan) secara in situ menunjukkan konstribusi terhadap kandungan logam berat pada sedimen. Secara keseluruhan, kandungan logam berat Cd pada sedimen di setiap lokasi penelitian tidak melebihi baku mutu, sedangkan kandungan logam berat pada sedimen yang melebihi atau mendekati baku mutu yaitu logam berat timbal. The sediments contain lead (Pb) and cadmium (Cd) from industrial waste were often found to enter nearby waters and accumulates at river mouths. Trimulyo Beach is adjacent to the Terboyo Industrial Estate on Semarang's coast, which has the potential to dump heavy metal waste into the waters. Heavy metal waste from industry in Tugu District that enters the Tapak River might also pollute Tirang Beach. The aim of the study is to determine the Pb and Cd content of sediments at Trimulyo and Tirang beaches. The research was conducted by using an exploratory survey method, and the research site was determined using a purposive sampling method. Using the sediment core, sediment samples were taken three times in each location. The levels of Pb and Cd metals in sediment samples were analysed using an Atomic Absorption Spectrophotometer (AAS) at the Semarang BBTPPI Laboratory. The analysis of the metal content of Pb in the sediment showed that Tirang Beach had the highest concentration of heavy metal at 49.16 mg/kg, and Trimulyo Beach had the highest Pb content at 23.78 mg/kg. The results showed that the Cd metal content in sediments at Trimulyo Beach and Tirang Beach was >0.050 mg/kg. Environmental parameters measured in situ (temperature, salinity, pH, DO, current velocity, and water clarity) made a contribution to the heavy metal content in the sediment. Overall, the heavy metal content of Cd in the sediment at each research location did not exceed the quality standard, while the lead heavy metal exceeded or approached the quality standard.
19
Gaston, Gary R., Chet F. Rakocinski, Steven S. Brown e Carol M. Cleveland. "Trophic function in estuaries: response of macrobenthos to natural and contaminant gradients". Marine and Freshwater Research 49, n. 8 (1998): 833. http://dx.doi.org/10.1071/mf97089.
Testo completoAbstract (sommario):
Trophic ecology of macrobenthic communities in estuaries of the northern Gulf of Mexico was used to infer community function, determine effects of contaminants on macrobenthos, and provide insight into community responses following disturbance. The taxa that numerically dominated the region included few large, deep-burrowing suspension feeders that typify estuaries elsewhere. This pattern is indicative of disturbance, and results in dominance by trophic groups that live near the sediment–water interface (early benthic-community succession). Trophic structure was significantly related to several sediment contaminants (especially metals, polynuclear aromatic hydrocarbons, DDT), and three environmental gradients (salinity, depth, and sediment silt–clay content). Generally, trophic diversity increased and proportion of subsurface-deposit feeders (SSDF) decreased with salinity, meaning that a more even distribution of trophic structure was found at high-salinity stations. The trophic shift toward dominance by shallow, subsurface-deposit feeders in contaminated habitats may have dire implications for fisheries. Several important commercial and recreational fisheries of the region depend on fish that feed primarily at the sediment surface. Higher proportion of subsurface-deposit feeders, coupled with low macrobenthic density in contaminated sediments, may imply that limited energy is transferred to higher trophic levels.
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Sari, Tri Wulan, Denny Yatmadi, Rommy Martdianto e Sujito Sujito. "INFLUENCE OF SALINITY LEVELS ANALYSIS ON SETTLING VELOCITY OF FINE SEDIMENT GRAINS IN CILIWUNG ESTUARY". Logic : Jurnal Rancang Bangun dan Teknologi 22, n. 2 (30 luglio 2022): 110–18. http://dx.doi.org/10.31940/logic.v22i2.110-118.
Testo completoAbstract (sommario):
Transport of estuarine sediment have a highly complex method, which is the combined effects result of periodically reciprocating flow, ocean waves, and the electrochemical characteristic of sea water [1]. Settling velocity (SV) is such a parameter fundamental for sediment researchers so that its accurate resolution has been regarded as a top priority in correcting modelling numerical and conceptual understanding of fine sediment dynamics [2] [3]. The goal of this study is to analyze the effect of salinity levels on the settling velocity of fine sediment grains in the Ciliwung estuary, Jakarta. The method used is direct measurement using the hydrometer analysis method. The result of experiment shows salinity levels affect the settling velocity of fine sediment grains in the Ciliwung estuary. The higher salinity, more faster the settling velocity of fine sediment grains. The average settling velocity at distilled water salinity 0 ppt is 1.083 mm/minute, sea water with salinity 0.3 ppt is 1.537 mm/minute, and sea water with salinity of 0.6 ppt of 1.561 mm/minute.
21
Roberts, D., A. McMinn e D. Zwartz. "An initial palaeosalinity history of Jaw Lake, Bunger Hills based on a diatom–salinity transfer function applied to sediment cores". Antarctic Science 12, n. 2 (giugno 2000): 172–76. http://dx.doi.org/10.1017/s0954102000000225.
Testo completoAbstract (sommario):
Two sediment cores taken from Jaw lake (Bunger Hills, East Antarctica) were analysed for diatom composition and abundance. A diatom-salinity transfer function developed for the nearby Vestfold Hills was used to determine palaeosalinity reconstructions from the assemblages preserved in each of the cores. There is a large step-wise decrease in salinity in the second core from at least c. 4000 to c. 2000 uncorrected 14C yr BP. The salinity record from the first core starts at c. 3000 uncorrected 14C yr BP and is comparable with the salinity of the second core between c. 3000 and c. 2000 uncorrected 14C yr BP. Sudden lake water dilution in both cores at c. 1900 uncorrected 14C yr BP is followed by brief increases in lake water salinity between c. 1900 and c. 500 uncorrected 14C yr BP, after which gradual dilution to present occurs. This analysis of the local environmental history of this saline lake reveals a mid–late Holocene evolution of the lake basin similar to that documented from earlier marine and freshwater lacustrine sediments in the Bunger Hills. The high coherence of the independent sediment records suggests a robust general palaeosalinity reconstruction of the lake is achieved in addition to providing evidence for the fidelity of single sediment cores as useful and adequate representation of the palaeolimnological histories of Antarctic lakes.
22
Jiang, Hongchen, Hailiang Dong, Gengxin Zhang, Bingsong Yu, Leah R. Chapman e Matthew W. Fields. "Microbial Diversity in Water and Sediment of Lake Chaka, an Athalassohaline Lake in Northwestern China". Applied and Environmental Microbiology 72, n. 6 (giugno 2006): 3832–45. http://dx.doi.org/10.1128/aem.02869-05.
Testo completoAbstract (sommario):
ABSTRACT We employed culture-dependent and -independent techniques to study microbial diversity in Lake Chaka, a unique hypersaline lake (32.5% salinity) in northwest China. It is situated at 3,214 m above sea level in a dry climate. The average water depth is 2 to 3 cm. Halophilic isolates were obtained from the lake water, and halotolerant isolates were obtained from the shallow sediment. The isolates exhibited resistance to UV and gamma radiation. Microbial abundance in the sediments ranged from 108 cells/g at the water-sediment interface to 107 cells/g at a sediment depth of 42 cm. A major change in the bacterial community composition was observed across the interface. In the lake water, clone sequences affiliated with the Bacteroidetes were the most abundant, whereas in the sediments, sequences related to low G+C gram-positive bacteria were predominant. A similar change was also present in the archaeal community. While all archaeal clone sequences in the lake water belonged to the Halobacteriales, the majority of the sequences in the sediments were related to those previously obtained from methanogenic soils and sediments. The observed changes in the microbial community structure across the water-sediment interface were correlated with a decrease in salinity from the lake water (32.5%) to the sediments (approximately 4%). Across the interface, the redox state also changed from oxic to anoxic and may also have contributed to the observed shift in the microbial community.
23
Klein, Annaleise R., Darren S. Baldwin, Balwant Singh e Ewen J. Silvester. "Salinity-induced acidification in a wetland sediment through the displacement of clay-bound iron(II)". Environmental Chemistry 7, n. 5 (2010): 413. http://dx.doi.org/10.1071/en10057.
Testo completoAbstract (sommario):
Environmental context Acidification of inland waterways is an emerging issue worldwide, mostly because it disturbs the balance of reduced sulfur species in soils, sediments and mine tailings. We describe a pathway for wetland acidification through salt displacement and oxidation of Fe2+ from clay minerals. This alternative pathway for acidification raises environmental concerns because an increasing number of inland waterways are affected by increasing salinity. Abstract A wetland near the Murray River (south-eastern Australia) was found to have significant levels of exchangeable reduced iron (Fe2+) in the sediment clay-zone, and the potential for acidification under high salinity and oxidising conditions. Cation exchange experiments using purified clay from this site show relative affinities consistent with the lyotrophic series: Fe2+>Ca2+>Mg2+>H+>K+>Na+. This relative affinity is confirmed in Fe2+ displacement experiments using natural sediment clay. Proton production during oxidation of salt-treated sediments corresponds to that expected for the oxidation and hydrolysis of Fe2+ displaced from clay interlayers, taking into account the buffering properties of the sediment matrix. This work shows that wetland acidification can occur in low sulfur-containing wetlands and is not exclusively a problem associated with sulfidic sediments.
24
Wu, Chun Bin, Xiao Wen Deng, Xue Zhu Yuan, Hong Chen, Liang Yun Zhang e Yong Ji Jiao. "Simulation of Salinity in Artificial Lake in Coastal Region". Applied Mechanics and Materials 444-445 (ottobre 2013): 1127–31. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.1127.
Testo completoAbstract (sommario):
An artificial lake in coastal region was built based on from a sewage reservoir by clearing sediment. Because the high-salinity sediment on the bottom of the Lake and the high-salinity water body around the Lake, salinity of the lake will increase with time. It is necessary to predict and control salinity of the lake. Based on the field investigation on the sediment and water body around the lake, EFDC (environmental fluid dynamic code) was used to simulate the distribution of salinity in the Lake. Simulation shows that more kinds of water sources in different points not only ensure the control of salinity also ensure hydraulic circulation. The results provide the theoretical support for the scheme of supplying water.
25
Han, Mingxian, Huiying Yu, Jianrong Huang, Chuanxu Wang, Xin Li, Xiaodong Wang, Liu Xu, Jingjing Zhao e Hongchen Jiang. "Limited Microbial Contribution in Salt Lake Sediment and Water to Each Other’s Microbial Communities". Microorganisms 12, n. 12 (9 dicembre 2024): 2534. https://doi.org/10.3390/microorganisms12122534.
Testo completoAbstract (sommario):
Climate change and human activities have led to frequent exchanges of sedimentary and aquatic microorganisms in lakes. However, the ability of these microorganisms to survive in their respective habitats between saline lake sediment and water remains unclear. In this study, we investigated microbial sources and community composition and metabolic functions in sediments and water in Yuncheng Salt Lake using a combination of source tracking and Illumina MiSeq sequencing. The results showed that 0.10–8.47% of the microbial communities in the sediment came from the corresponding water bodies, while 0.12–10.78% of the sedimentary microorganisms contributed to the aquatic microbial populations, and the microbial contributions depended on the salinity difference between sediment and water. Habitat heterogeneity and salinity variations led to the differences in microbial diversity, community composition, and assembly between sediment and water communities. The assembly of sedimentary communities was mainly controlled by stochastic processes (>59%), whereas the assembly of aquatic communities was mainly controlled by deterministic processes (>88%). Furthermore, sediments had a higher potential for metabolic pathways related to specific biogeochemical functions than lake water. These results provide insights into the survival ability of microorganisms and the mechanisms of microbial community assembly under frequent exchange conditions in saline lakes.
26
Febriyanti, Leti, Pujiono Wahyu Purnomo e Churun A’in. "KARAKTERISTIK OSEANOGRAFI DAN SEDIMENTASI DI PERAIRAN TEREROSI DESA BEDONO, DEMAK PADA MUSIM BARAT (Characteristics of Oceanography and Sedimentation of Waters Erosion in Bedono Village Demak during West season)". Management of Aquatic Resources Journal (MAQUARES) 6, n. 4 (25 luglio 2018): 367–75. http://dx.doi.org/10.14710/marj.v6i4.21325.
Testo completoAbstract (sommario):
Desa Bedono di wilayah Kecamatan Sayung Kabupaten Demak mengalami perubahan bentuk lahan akibat erosi. Erosi di Desa Bedono disebabkan oleh pengaruh kondisi hidrodinamika perairan akibat berubahnya tata guna wilayah perairan tersebut. Pendekatan analisis wilayah tererosi sangat diperlukan untuk pengelolaannya. Kondisi oseanogafi yang diamati yaitu pasang surut, arus, gelombang, kedalaman, suhu, dan salinitas serta sedimentasi. Tujuan dilakukannya penelitian ini adalah untuk mengetahui karakteristik oseanografi dan sedimentasi di daerah tererosi Desa Bedono. Acuan penelitian menggunakan metode survei. Penelitian dilaksanakan pada Januari 2017 di Desa Bedono Demak. Parameter oseanografi menggunakan 19 titik sampling, laju sedimentasi diambil dari 23 titik dengan sediment trap. Karakteristik oseanografi Perairan Bedono untuk kecepatan arus anara 0,1 – 0,8m/s, suhu permukaan laut 29 -34 ⁰C yang masih cocok untuk daerah penangkapan, salinitas 10 - 30‰, kedalaman 0,25 – 1,23m, tinggi gelombang sekitar 1,3m dilihat dari Laut Jawa, dan jenis pasang surut campuran condong ke harian tunggal. Pengaruh kedalaman air terjadi pada mulut kawasan erosi dan mengalami penurunan akibat reduksi kedalaman. Karakteristk Perairan Bedono dengan laju sedimentasinya yaitu sekitar 81,35 – 501,01 (mg/cm2/hari). Pada musim barat ini sedimentasi arahnya tinggi pada daerah dekat dengan garis pantai. Jenis sedimen yang terperangkap dalam sediment trap tersebut termasuk dalam jenis lempung berdebu dengan jenis sedimen berupa liat (clay) dan debu (silt). Pola sedimentasi berganttung pada kondisi fisik perairan yang bergantung pada musim. Sifat sedimentasi mempunyai kecenderungan kesamaan denngan kedalaman dan salinitas. Bedono village at the Sayung region, Demak regency experienced land change due to erosion. Erosion in Bedono Village is caused by the influence of water hydrodynamic conditions due to the changing of the use of the territorial waters. The analytical approach of the erosion area is needed for its management. Oceanography conditions observed were changes in tides, currents, waves, depth, temperature, and salinity while sedimentation conditions were sedimentation and sediment grains. The purpose of this study is to determine the characteristics of oceanography and sedimentation in the erosion area of Bedono village. Research reference using survey method. The research was conducted in January 2017 in Bedono Village, Demak. Oceanographic parameters used 19 sampling points, the rate of sedimentation used 23 points by sediment trap. Oceanographic characteristics in Bedono village, the current speed was between 0,1 – 0,8m / s, sea-surface temperature range to 29-34 ⁰C that still suitable for fishingground, salinity 10 - 30 ‰, depth 0,25 - 1,23m, height wave about 1,3 m seen from Java Sea, and the tidal type was mixed type but more to single daily type. The effect of water depth occurs on the mouth of the abraded area and decreases due to depth reduction. Sedimentation characteristics in Bedono waters with sedimentation rate is about 81,35 to 501,01 (mg / cm 2 / day). In the west season this sedimentation is heading high on the area close to the shoreline. Type of sediment trapped in the sediment trap is included in the silt clay type with sediment type in the form of clay and silt. Sedimentation pattern depends on the physical condition of the waters depending on the season. The nature of sedimentation has a tendency of similarity with depth and salinity.
27
Mwevura, Haji, Peter Nkedi-Kizza, Michael Kishimba e Henrik Kylin. "Adsorption-desorption of chlorpyrifos in soils and sediments from the Rufiji Delta, Tanzania". Western Indian Ocean Journal of Marine Science 19, n. 1 (29 ottobre 2020): 77–97. http://dx.doi.org/10.4314/wiojms.v19i1.7.
Testo completoAbstract (sommario):
Batch adsorption-desorption equilibrium techniques were used to investigate the adsorption capacity and influence of salinity on partitioning of the insecticide chlorpyrifos between water and soil or water and sediments from the Rufiji Delta. The data were fitted to different adsorption-desorption models and the hysteresis index was calculated using the ratio between the Freundlich exponents for desorption and adsorption, and secondly, the difference in area under the normalized adsorption and desorption isotherms using the maximum adsorbed and solution concentrations. The data showed non-linear adsorption and that chlorpyrifos was strongly adsorbed to soil and sediments from the Rufiji Delta. The linearized adsorption coefficient (KD) and Freundlich adsorption coefficient (Kf) correlated significantly with organic carbon content. Chlorpyrifos adsorption as well as hysteresis calculated by both methods decreased with salinity (i.e. the sediment adsorbs increasing amounts of chlorpyrifos with decreasing salinity). This indicates that settling of freshwater sediments is among the major removal pathways of the chemical from the water column, but increased turbulence during high tides may resuspend settled sediment simultaneously increasing salinity and re-dissolve chlorpyrifos. However, discharge of fresh water, particularly during heavy rains, increases the trapping efficiency of the sediments. The theoretical approach developed showed that the Langmuir model describes the desorption data better than the Freundlich model, and that a better index of hysteresis is one that considers areas under the adsorption and desorption isotherms, provided the desorption isotherm is described by the normalized Langmuir isotherm and the adsorption isotherm by the normalized Freundlich isotherm.
28
Miller, Madeline D., Mark Simons, Jess F. Adkins e Sarah E. Minson. "The Information Content of Pore Fluid δ18O and [Cl−]". Journal of Physical Oceanography 45, n. 8 (agosto 2015): 2070–94. http://dx.doi.org/10.1175/jpo-d-14-0203.1.
Testo completoAbstract (sommario):
AbstractPaleoceanographic proxies indicate that the ocean state during the Last Glacial Maximum (LGM) differed from the modern ocean state. Depth profiles of ocean sediment pore fluid δ18O and [Cl−] have been used to reconstruct the δ18O and salinity at the LGM. Here, it is investigated whether pore fluid profiles can constrain ocean δ18O and salinity at other times and, simultaneously, their ability to constrain the LGM δ18O and salinity. An inverse framework is developed that relies on Bayesian parameter estimation, thus allowing formal separation of prior assumptions from the information in observations. Synthetic problems are used to explore the information about past ocean tracers that can be recovered from pore fluid profiles. It is concluded that prior knowledge of deep ocean mixing time scales is essential to an accurate inverse estimate of LGM ocean salinity and δ18O from modern pore fluid profiles. The most recent 10 000 years of ocean salinity and δ18O and the error in their estimates are better constrained by the pore fluid profiles than are the LGM values. The inverse estimate of salinity and δ18O is strongly correlated with the estimate of diffusivity of oxygen isotopes and [Cl−] in sediment pore fluids. Uncertainty on the diffusivity of oxygen isotopes and chloride in sediments is reduced through inversion of the pore fluid profiles, but simultaneous estimation of δ18O or salinity and diffusivity increases the total uncertainty. The error reported in previous work may underestimate the true uncertainty of LGM deep ocean salinity and δ18O.
29
Akpovwovwo, Ufuoma. "MANGROVE GROWTH DYNAMICS AND SEDIMENT RELATIONS IN SOUTH WESTERN NIGERIA". Jurnal Pengelolaan Sumberdaya Alam dan Lingkungan (Journal of Natural Resources and Environmental Management) 10, n. 4 (30 dicembre 2020): 688–98. http://dx.doi.org/10.29244/jpsl.10.4.688-698.
Testo completoAbstract (sommario):
The mangrove ecosystem is not exempted from the fundamental interlinkages of components ensuring their functionality and development. Proper understanding of the interrelations between sediment parameters and their potential influence on mangrove growth is limited. This study examined mangrove structure across South western Nigeria, their growth dynamics, successional stage and relationship with the underlying sediments. Vegetation measurements and soil sampling (0-30cm) were carried out in one hundred quadrats of 20m by 20m. Sediments underwent laboratory analysis using standard procedures. Multiple regression was used to evaluate the relationship between the sediments and structural parameters at the 0.05 significance level. Ongoing degradation was detected, with evidence of selective harvesting targeted in the critical younger classes of <6cm, 6.1-9cm and 9.1-13cm. Phosphorus, magnesium, pH, salinity, sodium, silt and organic carbon were significant factors, contributing approximately 53 percent to the height. Electrical conductivity, organic carbon, salinity, total acidity, pH and silt were significant factors, contributing approximately 56 percent to the girth. The mangrove forests, though at a matured stage, are endangered. Sediment parameters, especially texture, have a significant influence on mangrove growth. Preparation of specialised sediment treatments for mangrove regrowth sites and also the setting up of conservation sites should be adopted.
30
Uddin, Md Riaz, Ashraf Uddin, Ming-Kuo Lee, Jake Nelson, Anwar Zahid, Md Maruful Haque e Nazmus Sakib. "Geochemistry of Arsenic and Salinity-Contaminated Groundwater and Mineralogy of Sediments in the Coastal Aquifers of Southwest Bangladesh". Water 16, n. 10 (18 maggio 2024): 1442. http://dx.doi.org/10.3390/w16101442.
Testo completoAbstract (sommario):
This study aimed to develop a geochemical database by thoroughly analyzing groundwater and sediments from coastal aquifers of southwest Bangladesh. Moreover, we investigated the source of sediment deposition and the mechanisms behind the presence of arsenic and salinity in groundwater. The seasonal distribution patterns of arsenic among the shallow and deep coastal aquifers were found to be 45.12 µg/l and 20.65 µg/l during dry and wet seasons, respectively. Moreover, the groundwater salinity distribution ranged from 3262.88 mg/l to 1930.88 mg/l during the dry and wet seasons. Cored sediment samples showed fine to medium sands of 92%, with silt and clay particles. The petrographic study of authigenic and heavy minerals revealed that the mineral grains were subangular to angular, indicating their textural immaturity of coastal sediments. The reactivity of goethite (FeOOH) and siderite (FeCO3) minerals suggests that the aquifers were subjected to slightly oxidized to moderately reducing conditions, with ORP values ranging from +50.40 mv to −149.5 mv. Such redox conditions could potentially result in the enrichment and mobility of arsenic in the groundwater. Although arsenic concentrations in deep aquifers are relatively low, higher salinity values are found in both shallow and intermediate coastal aquifers.
31
Pham, H. Q., K. T. Hoang, A. T. Bui e S. T. Le. "Variation in sediment characteristics between canopy gap and surrounding forest in Can Gio Mangrove Biosphere Reserve, Vietnam". IOP Conference Series: Earth and Environmental Science 1247, n. 1 (1 settembre 2023): 012001. http://dx.doi.org/10.1088/1755-1315/1247/1/012001.
Testo completoAbstract (sommario):
Abstract This study presented the difference in the sediments under a large gap formed by the Durian typhoon in 2006 and its surrounding intact forest in Can Gio Mangrove Biosphere Reserve, Vietnam. Twelve plots previously settled in the original gap and its surrounding forest were used to collect sediments in the dry and wet season in 2019 to assess the difference in sediment properties and nutritional state caused by the self-recovery of the vegetation. Sediment temperature and pH were measured in field, while the contents of total organic carbon (Corg) and total nitrogen (Ntot) were subsequently quantified in the chemical laboratory. Sediment temperature, salinity, and pH between the gap and the surrounding forest were not statistically different. The variation of Corg concentration in the gap sediments seemingly increased with depth from 1–15 cm in the dry season. The Ntot in the gap sediments showed that it was continuously consumed in the underlying sediments during both seasons. In conclusion, the variation in vegetation composition between the gap and its surrounding forest was responsible for the differences in sediment C and N concentrations.
32
Kotrys, Bartosz, Michał Tomczak, Andrzej Witkowski, Jan Harff e Jan Seidler. "Diatom-based estimation of sea surface salinity in the south Baltic Sea and Kattegat". Baltica 27, n. 2 (20 febbraio 2014): 131–40. http://dx.doi.org/10.5200/baltica.2014.27.22.
Testo completoAbstract (sommario):
A new diatom-based sea surface salinity (SSS) estimation has been applied to a collection of 27 taxa in 48 present-day sediment and surface water samples recovered in the Baltic Sea and Kattegat. The sediment core 303610-12 (2005) from the Eastern Gotland was chosen for study of Holocene sequence, ranging the last 8160 yrs BP. The Artificial Neuronal Network (ANN) method allows the estimation of spring SSS (March-April) values ranging between 7.04 ‰ and 8.25 ‰ at an averaged Root Mean Squared Error (RMSE) of 0.49 ‰. The rather low amplitude of salinity change might be caused by mixing of fresh water with upper surface layer of the Baltic Sea due to high precipitation and riverine input. The estimates of spring SSS from core 303610-12 were compared with independent geochemical proxies for salinity (K, Ti and S) derived from XRF Core Scanner record. Conspicuous correlation between salinity and sulphur records and reverse-correlation to K and Ti demonstrates that the ANN method combined with quantitative and qualitative analyses of diatoms provides a useful tool for palaeosalinity reconstructions in the Holocene sediments of the Baltic Sea
33
Shen, Jian, Dianci Chi e Bingrou Xi. "Sediment distributions and transport patterns in the Pearl River Estuary and its adjacent coastal ocean". Advances in Engineering Technology Research 8, n. 1 (19 ottobre 2023): 398. http://dx.doi.org/10.56028/aetr.8.1.398.2023.
Testo completoAbstract (sommario):
Coastal sediment is important for the development of river deltas and for carrying both nutrients and pollutants into estuaries and coasts. Totally 265 surficial sediments collected from the Pearl River Estuary and its adjacent coastal ocean were analyzed by using Gao-Collins method to study the sediment transport path and deposition center. The Pearl River Estuary was an area of sandy mud sediment and showed some muddy patches. There were 5 distinguishable sediment convergence centers, which represent 3 types of sediment transport patterns and hydrodynamic environments. The net sediment transport pathways in the estuary and shelf sea were mainly in the offshore and landward direction, respectively. The analyzed results indicated that the main part of muddy sediment was confined to the mouth of the estuary due to the combined effects of the expansion and salinity intrusion.
34
Noor, Rahmat Januar, Muhammad Isman, Muhammad Imran Lapong e Fathuddin Fathuddin. "Analysis of the Rate and Nutrient Content of Sediment in The Coral Transplantation Installation Vertical Method on Samalona Island, Makassar City". Jurnal Sumberdaya Akuatik Indopasifik 8, n. 1 (29 febbraio 2024): 11–22. http://dx.doi.org/10.46252/jsai-fpik-unipa.2024.vol.8.no.1.382.
Testo completoAbstract (sommario):
Samalona Island is a small island that administratively belongs to the inner zone of the Spermonde Islands region with low live coral cover. One effort to improve coral conditions is to carry out vertical transplantation, but hydro-oceanographic conditions are thought to be an inhibiting factor, including sediment. The research carried out aims to determine the suitability of oceanographic parameters, estimate sediment rates, and determine the phosphate and nitrate in sediments. The research method used a field experiment method by taking water and sediment samples and installing sediment traps for 15 days. The parameters measured in situ are temperature, pH, current speed, salinity, and dissolved oxygen, while the ex-situ test is the dry weight of sediment, TSS, nitrate, and phosphate concentrations. Data analysis uses descriptive statistics and is categorized according to the evaluation instrument used. The research results show that the values for temperature, pH, current speed, salinity, and dissolved oxygen meet the standard criteria for coral-based on PP 21/2022. The sediment rate during the research period was 0,003 – 0,015 gr/cm2/day, so it was categorized as having the potential damage to corals with a mild to severe impact level. The nitrate concentration in sediment ranges from 0,19 – 0,25 ppm while phosphate ranges from 0,35 – 0,72 ppm, so it can be said to be waters with a medium trophic level (mesotrophic). The current speeds and sediment rates potentially accelerate nutrient concentrations and cause sediment resuspension, thereby closing coral polyps, especially on corals closest to the substrate where vertical coral transplant installations are installed.
35
Lin, Yuan, Huaitao Qin, Jin Guo e Jiawang Chen. "Study on the Rheological Behavior of a Model Clay Sediment". Journal of Marine Science and Engineering 9, n. 1 (14 gennaio 2021): 81. http://dx.doi.org/10.3390/jmse9010081.
Testo completoAbstract (sommario):
Clay sediments are the main component of seabed sediment. Interactions between the nano-sized, disk-shaped and charged clay particles are complicated, as they control the sediment’s rheology. In this study, we studied the rheological behavior of the clay sediment modeled by laponite and bentonite suspensions experimentally using a rotational rheometer. The yield stress decreased when water content increased. Meanwhile, the yield stress of the laponite suspension first increased and then decreased with increasing salinity. It is considered that the face-to-face repulsive electrostatic interaction between clay platelets dominated the yield behavior. A yield stress model was developed to describe the change of the yield stress with both the water content and the salinity. When the system started to flow, the viscosity decreased with increasing shear. A master curve of viscosity is was from the viscosity-stress curves at different water contents if the applied shear stress was normalized by the yield stress and the viscosity normalized by a characteristic viscosity. This study provides a preliminary understanding of the clay sediment rheology and its mechanism for the investigation on the flowing of the sediment systems with strong interparticle interaction.
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Gar'kusha, D., Yu Fedorov, R. Trubnik e N. Dotsenko. "Methane and hydrogen sulfide in the bottom sediments of the estuaries of the Azov-Black sea basin". Anthropogenic Transformation of Nature 8, n. 1 (2022): 6–20. http://dx.doi.org/10.17072/2410-8553-2022-1-6-20.
Testo completoAbstract (sommario):
In the summer-autumn period of 2013–2018, studies were conducted on the distribution of methane (CH4) and hydrogen sulfide (ΣH2S) in the estuaries of the Azov (Yeisky, Beisugsky, Sladky, Kurchansky and Akhtanizovsky) and Black (Vityazevsky, Kiziltashsky and Bugazsky) seas characterized by different salinity. For the first time, to characterize the conjugate distribution of CH4 and ΣH2S in the bottom sediments of aquatic ecosystems, the "methanization" coefficient was used, which is the percentage of CH4 from the sum of concentrations (in mg/g) of reduced gases – ΣH2S and CH4. Concentrations of CH4 and ΣH2S in bottom sediments of desalinated estuaries with water salinity from 0,26 to 8,20% (Sladky, Akhtanizovsky and Kurchansky) vary from 0,01 to 114,34 μg/g of wet sediment and from <0,001 to 3,07 mg/g of wet sediment, respectively. Concentrations of CH4 and ΣH2S in sediments of saline estuaries with water salinity from 10,7 to 58% (Yeisky, Beisugsky, Vityazevsky, Kiziltashsky and Bugazsky) vary from 0,01 to 1,44 micrograms/g and from 0,01 to 1,44 μg/g, respectively. The methanization coefficient in sediments of saline estuaries varies in the range from 0,002 to 1,38% and in 97% of the samples taken does not exceed 1%, which indicates a significant dominance of the sulfide formation process over the methanogenesis process. In the sediments of desalinated estuaries, the methanization coefficient increases markedly (up to 19,14%), while the proportion of sediments with a percentage of CH4 of more than 1% increases to 32%. The closeness of correlations between the studied reduced gases and hydrochemical parameters is analyzed.
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Jones, AR, CJ Watson-Russell e A. Murray. "Spatial patterns in the macrobenthic communities of the hawkesbury estuary, New South Wales". Marine and Freshwater Research 37, n. 4 (1986): 521. http://dx.doi.org/10.1071/mf9860521.
Testo completoAbstract (sommario):
Spatial patterns in the number of species, number of individual animals and community composition of the benthos of the Hawkesbury Estuary, N.S.W., are described and related to physicochemical factors. Replicate grabs were taken from deep and shallow sites located on transects across the estuary for each of five times at intervals of 3 months. The number of species and number of individuals always differed significantly along the estuary but the pattern of difference varied with both depth and time. Although a monotonic decline in the number of species along the estuary never occurred, the two most- seaward transects usually supported the most species and the three furthest-upstream transects the least. The number of species was usually more highly correlated with salinity than with sedimentary variables but salinity correlations were not always significant. The number of individuals was not related to any abiotic variable in a consistent way. Significant depth-related differences occurred only for the number of individuals although the pattern of difference varied among both transects and times. Sediment-associated differences also varied with transect and time. Where consistent differences occurred, highest species numbers were sometimes associated with sand and sometimes with coherent clay. Consequently the species-sediment relationship is not always a simple linear function of grain size and different aspects of sediment structure may be influential. Sediments with greater habitat heterogeneity sometimes supported more species and sometimes fewer species than more uniform sediments. Classification and ordination analyses revealed major patterns in community composition that were most closely related to salinity and minor patterns related to sediment grade. Community changes did not always correspond with physicochemical changes and hence the latter were not always good predictors of biological variables.
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Youssef, Noha H., Kristen N. Ashlock-Savage e Mostafa S. Elshahed. "Phylogenetic Diversities and Community Structure of Members of the Extremely Halophilic Archaea (Order Halobacteriales) in Multiple Saline Sediment Habitats". Applied and Environmental Microbiology 78, n. 5 (16 dicembre 2011): 1332–44. http://dx.doi.org/10.1128/aem.07420-11.
Testo completoAbstract (sommario):
ABSTRACTWe investigated the phylogenetic diversity and community structure of members of the halophilicArchaea(orderHalobacteriales) in five distinct sediment habitats that experience various levels of salinity and salinity fluctuations (sediments from Great Salt Plains and Zodletone Spring in Oklahoma, mangrove tree sediments in Puerto Rico, sediment underneath salt heaps in a salt-processing plant, and sediments from the Great Salt Lake northern arm) usingHalobacteriales-specific 16S rRNA gene primers. Extremely diverseHalobacterialescommunities were encountered in all habitats, with 27 (Zodletone) to 37 (mangrove) different genera identified per sample, out of the currently described 38Halobacterialesgenera. With the exception of Zodletone Spring, where the prevalent geochemical conditions are extremely inhospitable toHalobacterialessurvival, habitats with fluctuating salinity levels were more diverse than permanently saline habitats. Sequences affiliated with the recently described generaHalogranum,Halolamina,Haloplanus,Halosarcina, andHalorientalis, in addition to the generaHalorubrum,Haloferax, andHalobacterium, were among the most abundant and ubiquitous genera, suggesting a wide distribution of these poorly studied genera in saline sediments. TheHalobacterialessediment communities analyzed in this study were more diverse than and completely distinct from communities from typical hypersaline water bodies. Finally, sequences unaffiliated with currently described genera represented a small fraction of the totalHalobacterialescommunities, ranging between 2.5% (Zodletone) to 7.0% (mangrove and Great Salt Lake). However, these novel sequences were characterized by remarkably high levels of alpha and beta diversities, suggesting the presence of an enormous, yet-untapped supply of novelHalobacterialesgenera within the rare biosphere of various saline ecosystems.
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Zhao, Shengnan, Yunxi Zhao, Zhimou Cui, Hui Zhang e Jinda Zhang. "Effect of pH, Temperature, and Salinity Levels on Heavy Metal Fraction in Lake Sediments". Toxics 12, n. 7 (5 luglio 2024): 494. http://dx.doi.org/10.3390/toxics12070494.
Testo completoAbstract (sommario):
Heavy metals (HMs) in aquatic environments are characterized by high toxicity, a propensity for bioaccumulation, and non-degradability, and pose significant risks to biological communities. Previous studies of HMs in lakes have shown that the physical and chemical characteristics of the lake water may control both the migration of HMs in the sediments and the concentration of heavy metals in the lake water. In fact, the change in aquatic environments changes the heavy metal fraction in the sediment, which controls the release of HMs. In this paper, we investigated the effects of the pH, temperature, and salinity levels of overlying water on the chemical fraction of Cu and Zn in Wuliangsuhai Lake surface sediments. The results show that lower water pH and higher water salinity and temperature could increase Cu and Zn release from the sediment. An increase in pH led to changes in the speciation of solid fractions of Zn, namely increases in the residual fraction and decreases in the organic matter and sulfide, whereas acid-extractable and Fe-Mn oxide fractions remained largely the same. Increases in temperature and salinity led to opposite changes in the speciation of solid fractions, namely decreases in the residual fraction and increases in the organic matter and sulfide and Fe-Mn oxide fractions, whereas acid-extractable fractions remained largely the same. The effect of pH, temperature, and salinity on Cu fractions in the solids was much smaller. According to the ratio of the secondary phase to the primary phase (RSP), acidic, high-temperature, and high-salt conditions increase the release risks of Zn. Changes in water temperature have the greatest influence on the risk of Zn and Cu release from sediments, followed by the influence of salinity changes.
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Gagnon, Jean-Christophe, Valérie Turcotte Blais e Cassandre Sara Lazar. "Response of Hypolimnetic Water and Bottom Sediment Microbial Communities to Freshwater Salinization—A Microcosm Experiment". Applied Microbiology 3, n. 3 (19 agosto 2023): 915–34. http://dx.doi.org/10.3390/applmicrobiol3030063.
Testo completoAbstract (sommario):
The introduction of NaCl in freshwater caused by winter runoffs is a problem whose consequences are still little understood. We sought to analyze the effect of NaCl addition on microbial communities of the hypolimnion and bottom sediments of a Canadian lake. Using microcosms comprising a salinity gradient varying between 0.01 and 3.22 ppt (10–3220 mg/L−1) NaCl, we investigated the effect of salinity on prokaryotic absolute abundance and diversity, following a three- and six-week exposure, and detected the presence of a salinity threshold for microbial communities’ differentiation. We observed a significant decline of bacterial diversity after six weeks in hypolimnetic samples. In the sediments, no clear effect of NaCl was observed on abundance or diversity, despite the presence of variations throughout the salinity gradient. The implication of nutrient fluctuations as well as the co-occurrence of species and inter-domain interactions is likely and would strongly contribute to the development of salt-exposed prokaryotic communities. In hypolimnetic water and sediments, the archaeal and eukaryotic communities differed significantly from 0.93 ppt (930 mg/L−1), while only conclusive at 1.9 ppt (1900 mg/L−1) NaCl in bacteria, meaning that the regulations in place are possibly suitable for the protection of the microbial communities in the hypolimnion and sediment lake layers.
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Sun, Fu-Lin, You-Shao Wang, Mei-Lin Wu e Cui-Ci Sun. "Cyanobacterial community diversity in the sediments of the Pearl River Estuary in China". Scientia Marina 81, n. 4 (15 dicembre 2017): 477. http://dx.doi.org/10.3989/scimar.04106.07a.
Testo completoAbstract (sommario):
Cyanobacterial community diversity in the sediment of the Pearl River Estuary in China was evaluated in this study by denaturing gradient gel electrophoresis (DGGE) during the wet and dry seasons. Nucleotide sequences obtained from DGGE bands were classified into five cyanobacterial clusters, including Synechococcus, Cyanobium, Chroococcus, Prochlorales and Tolypothrix. Synechococcus was identified as the dominant cyanobacterial group in the sediment samples; its distribution varied from the inner estuary to the outer estuary, with a wide range of salinity adaptation. Observed patterns of cyanobacterial communities changed markedly between sampling sites and seasons, suggesting that most cyanobacteria were not delivered via fresh water. Canonical correspondence analysis was conducted to determine the relationship between environmental variables and bacterial community structures during the dry season. The results suggested that the cyanobacterial community was significantly influenced by pH, salinity, PO4-P and NO3-N in sediments.
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Casila, Joan Cecilia, Ryohei Okuyama e Katsuhide Yokoyama. "Factors affecting scum formation and the use of electronic nose to identify fundamental odor properties in urban estuaries". Estuarine Management and Technologies 1, n. 1 (7 giugno 2024): 39–56. http://dx.doi.org/10.3897/emt.1.119588.
Testo completoAbstract (sommario):
The foul odor of rivers is often linked to poor water quality and unhealthy air. In this study, variations in water quality and hydrodynamics near the confluence of the Shakujii and Sumida Rivers in Tokyo, Japan, were monitored, and their effects on sum generation were analyzed. The Shakujii River, facing scum and odor issues, was monitored hourly for on-site scum coverage. Samples of scum, sediment, and water were collected and subjected to odor analysis. The odor characteristics were assessed using an electronic nose odor machine and then correlated with human olfactory sense. Results indicated that salinity, dissolved oxygen (DO), rainfall, sediment, and topography influenced scum formation. Scum coverage was higher when salinity was below 1 psu and DO was below 6 mg/L. Organic acids (14.2%) and hydrogen sulfide (14.4%) were the primary odor components of sediment in the Shakujii River. In the Sumida River sediments, organic acids (4%) and sulfurs (1%) were prominent. The Shakujii River sediment exhibited the highest odor index and showed a 62.43% similarity with scum. These results could support efforts to address scum and odor issues in the area. They could provide new insights into on-site formation based on actual river hydrodynamics and water quality variations. Graphical abstract
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Emmerich, Maren, Ankita Bhansali, Tina Lösekann-Behrens, Christian Schröder, Andreas Kappler e Sebastian Behrens. "Abundance, Distribution, and Activity of Fe(II)-Oxidizing and Fe(III)-Reducing Microorganisms in Hypersaline Sediments of Lake Kasin, Southern Russia". Applied and Environmental Microbiology 78, n. 12 (13 aprile 2012): 4386–99. http://dx.doi.org/10.1128/aem.07637-11.
Testo completoAbstract (sommario):
ABSTRACTThe extreme osmotic conditions prevailing in hypersaline environments result in decreasing metabolic diversity with increasing salinity. Various microbial metabolisms have been shown to occur even at high salinity, including photosynthesis as well as sulfate and nitrate reduction. However, information about anaerobic microbial iron metabolism in hypersaline environments is scarce. We studied the phylogenetic diversity, distribution, and metabolic activity of iron(II)-oxidizing and iron(III)-reducingBacteriaandArchaeain pH-neutral, iron-rich salt lake sediments (Lake Kasin, southern Russia; salinity, 348.6 g liter−1) using a combination of culture-dependent and -independent techniques. 16S rRNA gene clone libraries forBacteriaandArchaearevealed a microbial community composition typical for hypersaline sediments. Most-probable-number counts confirmed the presence of 4.26 × 102to 8.32 × 103iron(II)-oxidizingBacteriaand 4.16 × 102to 2.13 × 103iron(III)-reducing microorganisms per gram dry sediment. Microbial iron(III) reduction was detected in the presence of 5 M NaCl, extending the natural habitat boundaries for this important microbial process. Quantitative real-time PCR showed that 16S rRNA gene copy numbers of totalBacteria, totalArchaea, and species dominating the iron(III)-reducing enrichment cultures (relatives ofHalobaculum gomorrense,Desulfosporosinus lacus, and members of theBacilli) were highest in an iron oxide-rich sediment layer. Combined with the presented geochemical and mineralogical data, our findings suggest the presence of an active microbial iron cycle at salt concentrations close to the solubility limit of NaCl.
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Vakalas, Ioannis, e Irene Zananiri. "Net Transport Patterns of Surficial Marine Sediments in the North Aegean Sea, Greece". Journal of Marine Science and Engineering 12, n. 3 (20 marzo 2024): 512. http://dx.doi.org/10.3390/jmse12030512.
Testo completoAbstract (sommario):
The spatial distribution of sediments on the seafloor reflects the various dynamic processes involved in the marine realm. To analyze sediment transport patterns in the North Aegean Sea, 323 surficial samples were obtained and studied. The granulometry data revealed a diverse range of grain sizes of surficial sediments, ranging from purely sandy to clay. The predominant size classes were silt and muddy sand, followed by sandy silt and mud. However, there were very few samples that fell within the clay classes. The sorting coefficient ranged from 0.21 to 5.48, while skewness ranged from −1.09 to 1.29. The sediment transport patterns were analyzed based on the grain-size parameters (mean, sorting, and skewness). The results showed the variability of flow parameters involved in sediment distribution. River influx and longshore drift near the shoreline are the most significant factors affecting sediment transport. At the open sea, sediment distribution is mainly controlled by general water circulation patterns, especially by the outflow of low-salinity waters from the Black Sea through the Dardanelles and the Marmara Sea. The heterogeneity of sediment textural parameters across the study area suggests that seafloor sediments are further reworked in areas where water masses are highly energetic. It can be concluded that open sea water circulation controls sediment distribution patterns at the open shelf, while close to the coast, river discharge plays a key role.
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Hapsari, Rania Widia, Boedi Hendrarto e Max Rudolf Muskananfola. "PEMETAAN KARAKTERISTIK FISIK SEDIMEN DI PANTAI BERMANGROVE DI PESISIR DESA TIMBULSLOKO, KABUPATEN DEMAKPEMETAAN KARAKTERISTIK FISIK SEDIMEN DI PANTAI BERMANGROVE DI PESISIR DESA TIMBULSLOKO, KABUPATEN DEMAK". Management of Aquatic Resources Journal (MAQUARES) 6, n. 3 (30 aprile 2018): 283–92. http://dx.doi.org/10.14710/marj.v6i3.20587.
Testo completoAbstract (sommario):
ABSTRAK Karakteristik fisik sedimen dan dinamika pergerakannya mempunyai peranan penting bagi stabilitas suatu kawasan pesisir. Desa Timbulsloko, Kabupaten Demak merupakan salah satu desa di kawasan pesisir yang memiliki pantai yang bermangrove. Sama dengan daerah pesisir lainnya, daerah ini juga mendapat pengaruh faktor lingkungan dari darat dan laut yang dikhawatirkan dapat menyebabkan perubahan garis pantai. Penelitian ini dilakukan guna menjawab permasalahan belum banyaknya informasi mengenai karakteristik fisik sedimen dalam hubungannya dengan mangrove di kawasan tersebut. Penelitian dilaksanakan pada Bulan Maret 2017 bertempat di Desa Timbulsloko, Kabupaten Demak. Penelitian bertujuan untuk mengetahui kondisi kawasan pesisir Desa Timbulsloko ditinjau dari karakteristik fisik sedimen dan kondisi kerapatan relatif hutan mangrovenya. Sampling sedimen dilakukan disepanjang pantai sejauh 775m. Beberapa metode yang dilakukan pada penelitian yaitu Metode Soil Jar Test, Haphazard, Point Centered Quarter, dan Principal Component Analysis. Hasil penelitian menunjukkan bahwa sedimen didominasi oleh fraksi lumpur (92,50%), sedimen memiliki warna coklat muda hingga kehitaman dengan nilai HUE 28,53-36,61o, salinitas sedimen berkisar antara 13,60-25‰. Jenis mangrove yang mendominasi kawasan tersebut yaitu Rhizophora sp.. Berdasarkan analisa PCA, fraksi liat dan lumpur dalam sedimen berkorelasi positif dengan kerapatan total mangrove. Kata Kunci : Karakteristik Fisik Sedimen; Kerapatan Relatif Hutan Mangrove; Desa Timbulsloko ABSTRACT The physical characteristics of sediment and the dynamics of its movement have an important role for the stability of a coastal region. Timbulsloko Village, Demak Regency is one of the villages in the coastal area overgrown by mangroves. Similar to other coastal areas, this area also has the effect of environmental factors from land and sea that are feared can cause coastline shifts. This research was conducted to answer the problem of the lack of information about the physical characteristics of sediment in relation to the mangroves in the area. The research was conducted in March 2017 at Timbulsloko Village, Demak Regency. This study aimed to determine the condition of coastal areas of Timbulsloko Village in terms of physical characteristics of sediment and relative density of mangrove forest conditions. Sediment sampling was done along the coast as far as 775m. Some method that used in this study are Soil Jar Test, Haphazard, Point Centered Quaretr, and Principal Component Analysis. The results showed that sediment was dominated by mud fraction (92,50%), sediment had light brown to blackish with HUE value 28,53-36,61o, sediment salinity was between 13,60-25 ‰. Type of mangrove that dominates the area is Rhizophora sp.. Based on PCA analysis, clay and mud fraction in the sediment correlated positively with the total relative density of mangrove. Keyword : Physical Characteristic of Sediment; Relative Density of Mangrove Forest; Timbulsloko Village
46
Song, Tianran, Qiyun Liang, Zhaozhong Du, Xiaoqun Wang, Guanjun Chen, Zongjun Du e Dashuai Mu. "Salinity Gradient Controls Microbial Community Structure and Assembly in Coastal Solar Salterns". Genes 13, n. 2 (21 febbraio 2022): 385. http://dx.doi.org/10.3390/genes13020385.
Testo completoAbstract (sommario):
Salinity acts as a critical environmental filter on microbial communities in natural systems, negatively affecting microbial diversity. However, how salinity affects microbial community assembly remains unclear. This study used Wendeng multi-pond saltern as a model to evaluate the prokaryotic community composition and diversity and quantify the relative importance of ecological processes across salinity gradients. The results showed that low-saline salterns (45–80 g/L) exhibited higher bacterial diversity than high-saline salterns (175–265 g/L). The relative abundance of taxa assigned to Halomicrobiaceae, Rhodobacteraceae, Saprospiraceae, and Thiotrichaceae exhibited a hump-shaped dependence on increasing salinity. Salinity and pH were the primary environmental factors that directly or indirectly determined the composition and diversity of prokaryotic communities. Microbial co-occurrence network dynamics were more complex in the sediment than in the water of salterns. An infer Community Assembly Mechanisms by Phylogenetic-bin-based null model analysis (iCAMP) showed that microbial community assembly in sediment and water differed. Our findings provide more information about microbial community structure and the importance of various ecological processes in controlling microbial community diversity and succession along salinity gradients in water and sediment.
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Gervasio, Maria Pia, Elisa Soana, Fabio Vincenzi e Giuseppe Castaldelli. "An Underestimated Contribution of Deltaic Denitrification in Reducing Nitrate Export to the Coastal Zone (Po River–Adriatic Sea, Northern Italy)". Water 14, n. 3 (8 febbraio 2022): 501. http://dx.doi.org/10.3390/w14030501.
Testo completoAbstract (sommario):
In transitional environments, the role of sediments biogeochemistry and denitrification is crucial for establishing their buffer potential against nitrate (NO3−) pollution. The Po River (Northern Italy) is a worldwide hotspot of eutrophication. However, benthic N dynamics and the relevance of denitrification in its delta have not yet been described. The aim of the present study was to quantify the contribution of denitrification in attenuating the NO3− loading transported to the sea during summer. Benthic fluxes of dissolved inorganic nitrogen (N) and denitrification rates were measured in laboratory incubations of intact sediment cores collected, along a salinity gradient, at three sections of the Po di Goro, the southernmost arm of the Po Delta. The correlation between NO3− consumption and N2 production rates demonstrated that denitrification was the main process responsible for reactive N removal. Denitrification was stimulated by both NO3− availability in the Po River water and organic enrichment of sediment likely determined by salinity-induced flocculation of particulate organic load, and inhibited by increasing salinity, along the river–sea gradient. Overall, denitrification represented a sink of approximately 30% of the daily N loading transported in middle summer, highlighting a previously underestimated role of the Po River Delta.
48
Verdelhos, Tiago, Helena Veríssimo, João Carlos Marques e Pedro Anastácio. "Behavioural Responses of Cerastoderma edule as Indicators of Potential Survival Strategies in the Face of Flooding Events". Applied Sciences 11, n. 14 (12 luglio 2021): 6436. http://dx.doi.org/10.3390/app11146436.
Testo completoAbstract (sommario):
According to climate change scenarios the incidence of extreme events, such as flooding, is expected to increase worldwide. In the current climate change context, understanding behavioural responses of marine species to such stressors is essential, especially for species of high ecological and economic interest such as bivalves, which can be quite useful for future management and conservation actions. In this study, a laboratory experiment using different salinity conditions was undertaken to assess potential behavioural responses of cockles (Cerastoderma edule), as a survival strategy facing low-salinity stress during riverine flood events. Results showed consistent patterns of burrowing/emergence of cockles facing salinity variation: with high salinities the individuals were observed buried in the sediment; when salinity decreased, organisms were observed to actively emerge, and when salinity was <10, cockles were found exposed at the sediment surface. These behavioural changes may be a strategy for the survival of this species in response to flooding: once at the sediment surface, hydrodynamics may transport organisms towards areas that are more suitable
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Alhassan, Abdullahi Bala, e Mohammed Othman Aljahdali. "Nutrient and physicochemical properties as potential causes of stress in mangroves of the central Red Sea". PLOS ONE 16, n. 12 (23 dicembre 2021): e0261620. http://dx.doi.org/10.1371/journal.pone.0261620.
Testo completoAbstract (sommario):
Mangrove ecosystems are some of the most productive and important sinks for sediment globally. Recently, there has been an increasing interest in possible causes of stress in mangroves, such as nutrient limitation, high salinity, solar radiation and temperature. We measured different factors casing stress and determined how they influenced oxidative stress and growth biomarkers in six study sites dominated by mangroves; Al Lith, South Jeddah, Dahban, Thuwal, Rabigh and Mastorah. Significant differences (P < 0.05) were recorded in water salinities and temperatures, nitrogen and phosphorus content in sediments, and antioxidant enzyme activities in different study sites. The highest salinity (40.75 ‰) and temperature (29.32°C) were recorded in the Rabigh mangrove stand, which corresponds to the lowest dissolved oxygen (5.21 mg/L). Total organic carbon, total nitrogen and total phosphorus in sediment across the study areas were in the order Rabigh>Thuwal>Dahban>Al Lith>South Jeddah>Mastorah. Total nitrogen in mangrove leaves at Rabigh was the highest and about 1.3 times higher than the total nitrogen in South Jeddah mangrove ecosystem, very different from the ratio of total nitrogen in the sediments at Rabigh and South Jeddah mangrove ecosystems. The average values of δ13C (-17.60‰) and δ15N (2.84‰) in the six mangrove ecosystems, and the highest δ13C (-13.62‰) and δ15N (4.39‰) at Rabigh in the sediments suggest that nutrient input differed among study sites. Higher nutrient levels at Rabigh mangrove ecosystem were attributed to restricted circulation, camel grazing and land runoff with agricultural waste during seasonal flooding events. However, N limitation and possibly salinity contributed to stress in Al Lith, South Jeddah, Dahban, Thuwal, Rabigh, and Mastorah mangrove ecosystems. Salinity (r = 0.9012) contribute more to stress at Rabigh.
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Casacchia, Alicia, Megan Ballard, Kevin M. Lee, Preston S. Wilson e Nicholas P. Chotiros. "The effect of salinity on the rigidity and settling behavior of reconstituted water-saturated kaolinite sediments". Journal of the Acoustical Society of America 155, n. 3_Supplement (1 marzo 2024): A173. http://dx.doi.org/10.1121/10.0027212.
Testo completoAbstract (sommario):
In sandy sediments, the salinity of the pore water only affects the sound speed of the mixture by way of affecting the sound speed of the pore water. With clay mineral and saltwater mixtures, the intergranular forces that depend on the salinity of the pore water affect the sediment acoustic properties beyond simply affecting the sound speed of the pore water. These dependencies were investigated via image analyses of prepared samples of two kaolinite clay types (Flat DS and RSA) via analyses of their settling dynamics, porosity, and rigidity as a function of pore water salinity. There exists an observable dependence on salinity to mixture porosity and rate of settling. In addition, three regimes of slip-stick dynamics are shown to exist at different salinity ranges: (a) an immediate transition to liquid-like behavior; (b) a viscoelastic transition to liquid-like behavior with long term creep; and (c) a delayed transition to viscoelastic behavior with long term creep. [Work supported by ONR.]