Ratios In Sediments Research Articles

Effect of reduced graphene oxide and MnFe2O4 nanoparticles on carbonyl iron for magnetorheological fluids

This study introduces magnetic MnFe2O4 nanoparticles and graphene oxide (GO) nanosheets to enhance magnetorheological (MR) properties and dispersion stability of the carbonyl iron (CI)-based MR fluid. The prepared CI/MnFe2O4/GO was transformed into CI/MnFe2O4/rGO through an annealing process and was used as an additive of the MR fluid. The shape, crystallinity, and magnetic properties of the composite were analyzed via SEM, TEM, EDS, XRD, and vibrating sample magnetometer. In addition, rotational rheometer and Turbiscan were used to examine the MR properties and dispersion stability of the MR fluid, respectively. The CI/MnFe2O4/rGO-based MR fluid exhibited higher shear stress, shear viscosity, and storage modulus than the CI-based MR fluid. The dispersion stability was enhanced due to GO with its low density and a large specific surface area, and the sedimentation ratio was improved approximately by 17% after 24h owing to the reduced difference in the density between the magnetic particles and oil medium.

Past climate variations recorded in needle-like aragonites correlate with organic carbon burial efficiency as revealed by lake sediments in Croatia

The drivers of organic carbon (OC) burial efficiency are still poorly understood despite their key role in reliable projections of future climate trends. Here, we provide insights on this issue by presenting a paleoclimate time series of sediments, including the OC contents, from Lake Veliko jezero, Croatia. The Sr/Ca ratios of the bulk sediment are mainly derived from the strontium (Sr) and calcium (Ca) concentrations of needle-like aragonite in Core M1-A and used as paleotemperature and paleohydrology indicators. Four major and six minor cold and dry events were detected in the interval from 8.3 to 2.6 calibrated kilo anno before present (cal ka BP). The combined assessment of Sr/Ca ratios, OC content, carbon/nitrogen (C/N) ratios, stable carbon isotope (δ13C) ratios, and modeled geochemical proxies for paleoredox conditions and aeolian input revealed that cold and dry climate states promoted anoxic conditions in the lake, thereby enhancing organic matter preservation and increasing the OC burial efficiency. Our study shows that the projected future increase in temperature might play an important role in the OC burial efficiency of meromictic lakes.

Sr-Nd isotope and REE compositions of surface sediments from the three Gorges Reservoir: Implications for source identification and apportionment

Sediment deposition has already been considered to be a potential risk to the general running of the Three Gorges Reservoir (TGR). Identifying the sediment sources and their contributions to the TGR is of great significance for the sustainable management of reservoir operation. In this study, surface sediments of the TGR and its main tributaries were sampled in the flood (June to September), dry (November to next February) and even (March to May, October) seasons, 2017–2018, together with surrounding upland soils, and analyzed for Sr-Nd isotopes and rare earth elements (REE). The geochemical results showed that εNd(0) values and 87Sr/86Sr ratios of surface sediments from the TGR mainstream varied from − 12.21 to − 9.75 and from 0.720241 to 0.726655, respectively. All sediment and upland soil samples generally showed the LREE enrichment and significant Eu depletions. Three potential sources were identified for the TGR sediments and ranked in the order: regional source (adjacent tributaries) > distal source (upstream tributaries) > proximal source (upland soil), based on the Sr-Nd isotopes and REE parameters. Isotopic mixing model coupled with Monte-Carlo simulations was firstly applied to quantify source contributions to the TGR sediments among different seasons. Through Monte-Carlo model simulations, the regional source contributed approximately 40% to the TGR sediments during the flood and even seasons but approximately 50% during the dry season. The contribution from distal sources arrived at about 30% in the three seasons, and 30% from proximal sources during flood and even seasons and 20% in the dry season. Dam construction was the primary factor affecting the sediment deposition in the TGR, and it would further reduce sediment supply from the distal source with the operation of new increasing dams in the upper Yangtze River Basin. Hence, more attention should be paid to the regional sediment supply of the TGR in the future.

Relationships between the sound speed ratio and physical properties of surface sediments in the South Yellow Sea

Relationships between the sound speed ratio and physical properties of surface sediments in the South Yellow Sea

Iron‐Mediated Organic Matter Preservation in the Mississippi River‐Influenced Shelf Sediments

AbstractContinental shelves are important land–ocean interfaces where natural and anthropogenic processes as well as sediment geochemistry regulate organic matter sequestration. The major objective of this work is to understand spatial variability in reactive iron (rFe) bound organic carbon (OC) during low‐ and high‐flow conditions in the recent sediments of the Mississippi River‐influenced Louisiana shelf in the Northern Gulf of Mexico. Sediment samples were collected from five sites along the river plume during low (August 2016) and high (May 2017) discharge. Reactive iron was significantly higher in May (6.9 ± 1.7 mg g−1dw) compared to August (4.3 ± 0.9 mg g−1dw), while OC in August (11.9 ± 3.7 mg g−1dw) and May (7.8 ± 4.8 mg g−1dw) was similar. The fraction of OC bound to rFe (Fe‐OC) in the sediment in May (2.4 ± 1.5 mg g−1dw) was not significantly different from August (3.7 ± 2.7 mg g−1dw). Molar OC:Fe ratios in the rFe‐associated OC ranged between 0.9 and 6.2, with higher ratios in the deeper sediments (6–20 cm). Our results show that 31.7% ± 6.2% of the total OC in the recent sediments is associated with the rFe phase. Sediment mineralogical composition was characterized using X‐ray diffractometry and Fe‐K edge X‐ray absorption near edge structure spectroscopy. Our findings indicate that most of the iron is present as nonreactive iron in clay mineral smectite and the dominant form of rFe associated with OC is goethite.

Determination of sources, spatial variability, and concentration of polycyclic aromatic hydrocarbons in surface water and sediment of Imiringi River

Polycyclic aromatic hydrocarbons (PAHs) are very toxic and persistent environmental micro-contaminants that possess health-impacting tendencies. Environmental levels of PAHs are mainly exacerbated by anthropogenic activities. At elevated concentrations, PAHs become toxic and readily bio-magnify across the food chain. This study was undertaken to determine the concentration and identify possible sources of PAHs in Imiringi River. PAH concentrations depicted the following ranges; Oswan-1 (0.00046 – 0.05010 mg/L and 0.00002 – 0.01812 mg/kg); Olem-1 (0.02428 - 2.86264 mg/L and 0.00151 - 3.96536 mg/kg); Oswan-4 (0.00041 - 0.30012 mg/L and 0.00143 - 0.04530 mg/kg) for water and sediment samples respectively. PAHs mostly exceeded the recommended maximum contaminant levels (MCL) stipulated by United States Environmental Protection Agency (USEPA), while high molecular weight PAHs (4 – 6 ring PAHs) are prevalent in the environment. The applied diagnostic ratio (fluoranthene/pyrene) values for surface waters at Oswan-1 (0.8364) and Olem-1 (0.7337), and sediment at Olem-1 (0.4894) were less than 1, thereby reflecting petrogenic PAHs (from gasoline and diesel). On the other hand, Fluoranthene/Pyrene ratio of sediments from Oswan-1 (2.4558), Oswan-4 (2.3565) and surface water at Oswan-4 (2.0252) depicted values greater than 1, indicating pyrogenic PAHs (from coal combustion). Results further showed Fluoranthene/(Fluoranthene + Pyrene) ratio for all sampling locations at values greater than 0.4 for both surface water and sediment. Hence, revealing pyrogenic source PAHs (from combustion of fossil fuel, coal, grass, wood, etc). Overall, the water body showed reasonable hydrocarbon contamination. As such, it is unsuitable for consumption, as well as recreational and agricultural activities. The application of One-way ANOVA statistics showed spatial variability (p < 0.05) for different PAH species across different sections of river, while principal component analysis (PCA) revealed discrete similarities for most PAHs, excluding anthracene and Dibenz(a,h)anthracene.

English

BACKGROUND Neonatal septicaemia is a bacterial infection with positive blood culture in first four weeks of life. The early sepsis screen is vital as it detects earlier and benefits the clinician to treat the infection reducing neonatal mortality and morbidity. We wanted to evaluate various haematological screening parameters and C-reactive protein (CRP) in blood culture positive neonates in sepsis. METHODS This prospective study was conducted for a period of one year. Blood samples from hundred clinically suspected neonatal septicaemia cases were subjected to aerobic culture and sepsis screen tests like C-reactive protein, erythrocyte sedimentation ratio (ESR), total WBC count, absolute neutrophil count, immature / total neutrophil count (I / T) ratio and platelet count. The culture results were correlated with the sepsis screen tests. RESULTS Of the hundred cases studied, 18 % were blood culture positive and 66 % were males. Early onset septicaemia was more common, seen in 64 % of cases than late onset septicaemia (26 %) cases. Staphylococcus aureus was the commonest organism isolated in 38.46 % of cases followed by Klebsiella pneumoniae & E. Coli. Among the haematological parameters, the positivity was best with Creactive protein (94.44 %) followed by immature & mature neutrophil ratio (I / M) (94.44 %), I / T ratio (88.88 %) and the least with absolute neutrophil count (66.0 %). Any two or more parameters were positive in 94.44 % of the subjects. CONCLUSIONS Sepsis screen has good sensitivity, specificity and is a valuable aid for early diagnosis of neonatal septicaemia. Sepsis screen is simple, cost effective, less time consuming and easy to perform. As an individual test C-reactive protein has shown highest sensitivity, specificity and is a sensitive and responsive indicator of neonatal sepsis. KEYWORDS Blood Culture, Neonatal Septicaemia, Sepsis Screen

High denitrification potential but low nitrous oxide emission in a constructed wetland treating nitrate-polluted agricultural run-off

Constructed wetlands (CW) can efficiently remove nitrogen from polluted agricultural run-off, however, a potential caveat is nitrous oxide (N2O), a harmful greenhouse gas and stratospheric ozone depleter. During five sampling campaigns, we measured N2O fluxes from a 0.53ha off-stream CW treating nitrate-rich water from the intensively fertilized watershed in Rampillon, France, using automated chambers with a quantum cascade laser system, and manual chambers. Sediment samples were analysed for potential N2 flux using the HeO2 incubation method. Both inlet nitrate (NO3-) concentrations and N2O emission varied significantly between the seasons. In the Autumn and Winter inlet concentrations were about 11mg NO3--NL-1, and<6.5mg NO3--NL-1 in the Spring and Summer. N2O emission was highest in the Autumn (mean±standard error: 9.7±0.2μgNm-2h-1) and lowest in the Summer (wet period: 0.2±0.3μgNm-2h-1). The CW was a very weak source of N2O emitting 0.32kg N2O-Nha-1yr-1 and removing around 938kg NO3--Nha-1yr-1, the ratio of N2O-N emitted to NO3--N removed was 0.033%. The automated and manual chambers gave similar results. From the potential N2O formation in the sediment, only 9% was emitted to the atmosphere, the average N2 N 2O ratio was high: 89:1 for N2-Npotential: N2O-Npotential and 1353:1 for N2-Npotential: N2O-Nemitted. These results indicate complete denitrification. The focused principal component analysis showed strong positive correlation between the gaseous N2O fluxes and the following environmental factors: NO3--N concentrations in inlet water, streamflow, and nitrate reduction rate. Water temperature, TOC and DOC in the water and hydraulic residence time showed negative correlations with N2O emissions. Shallow off-stream CWs such as Rampillon may have good nitrate removal capacity with low N2O emissions.

Influence of different fumed silica as thixotropic additive on carbonyl particles magnetorheological fluids for sedimentation effects

The present work reports the influence of different types of surface area, hydrophobic, and hydrophilic fumed silica mixed in silicone oil as a thixotropic additive on carbonyl particles based magnetorheological fluids (MRFs) were prepared. Scanning electron microscopy analysis confirms the fumed silica particles attached to the surfaces of CIPs. The vibrating sample magnetometer result shows the MRF4 and 5 have a better magnetic saturation value of 30.12 emu/gm and 40.12 emu/gm, respectively. The experimental rheological flow curve behaviours are investigated using the magnetorheometer. The Herschel–Bulkley rheological model is found to be in good agreement with the experimental curves and suggested shear thinning property is observed. The results showed that the hydrophilic silica with larger surface area type presented (i.e.MRF 4 and 5) better magnetorheological fluid characteristics in terms of shear stress, with a high value of dynamic yield stress, and have much-improved sedimentation ratio up to seven days.

Effects of bentonite on the growth process of submerged macrophytes and sediment microenvironment

The effects of clay mineral bentonite on the growth process of submerged macrophyte V. spiralis and sediment microenvironment were investigated in the study for the first time, aiming to determine whether it is suitable for application in the field of ecological restoration. The growth index, and physiological and biochemical index of V. spiralis in the experiments were measured once a month, and the changes of rhizosphere microorganisms and physicochemical properties of sediments were also studied at the same time. The results demonstrated that bentonite can effectively promote the growth of V. spiralis. The treatment groups of RB1/1 and MB1/5 (the mass ratios of bentonite to sediment were 1/1 and 1/5, respectively.) showed the best V. spiralis growth promotion rates which were 18.78%, and 11.79%, respectively. The highest microbial diversity and abundance existed in group of RB10 (the mass ratio of sediment to bentonite was 10/1), in which the OTUs, Shannon, Chao and Ace were 1521.0, 5.20, 1712.26, and 1686.31, respectively. Bentonite was conducive to the propagation of rhizosphere microorganisms, and further changed the physical and chemical properties of the sediment microenvironment. The nutrient elements dissolved from bentonite may be one of the main reasons that promoted the growth of V. spiralis. The purpose of this result is to prove that bentonite can be further applied as sediment improver and growing media in ecological restoration projects in eutrophic shallow lakes.

Beryllium isotopes in sediments from Lake Maruwan Oike and Lake Skallen, East Antarctica, reveal substantial glacial discharge during the late Holocene

Constraining East Antarctic Ice Sheet (EAIS) evolution during the Holocene is important for exploring the forcing mechanisms behind ice sheet retreat and to constrain numerical ice sheet models that aid predictions of future sea-level rise. Beryllium (Be) isotope analysis of bedrock and marine sediments have offered unparalleled insight into Antarctic ice sheet history since the Pliocene, but much of EAIS remains poorly studied. Here, we report the reactive (authigenic) 10Be abundance, 9Be abundance and 10Be/9Be ratios of Antarctic lake sediments, for the first time, from Lake Maruwan Oike and Lake Skallen along Soya Coast of Lützow-Holm Bay, East Antarctica. Beryllium isotope records reveal melting of local glaciers associated with higher subglacial erosion between ∼4.1 and ∼3.6 ka BP. Comparison to marine records from the Antarctic continental shelf suggests this was part of a circum-Antarctic phenomena that led to widespread glacial discharge from other sectors of the East and West Antarctic Ice Sheet. We suggest the incursion of relatively warm Circumpolar Deep Water (CDW) into Lützow-Holm Bay during the Late Holocene led to frontal and basal melting of ice sheets along the Soya Coast, supporting the notion of Antarctic ice sheet instabilities as a contributor to global sea-level rise since the Mid Holocene.

Assessing the effects of lake-dredged sediments on soil health: Agricultural and environmental implications for northwestern Ohio.

Dredging operations produce large amounts of sediments, and when open lake disposal is used, it can pose a threat to water quality. This study examined the potential to use dredged sediment as a farm soil amendment. We conducted greenhouse experiments to determine (a) the physico-chemical health of a farm soil amended with various dredged sediment ratios, (b) nutrient dynamics when the soil blends were subjected to simulated storm events, and (c) the effect of dredged sediment on soybean [Glycine max (L.) Merr.] belowground biomass and yield. The soil blends consisted of 100% farm soil, 90% farm soil to 10% dredged sediment, 80% farm soil to 20% dredged sediment, or 100% dredged sediment. After 123 d, the soybean plants were harvested, and physico-chemical analyses were conducted on the soil, soybeans, and percolated stormwater. We found that dredged sediment amendment improved soil health by increasing soil organic matter, cation exchange capacity, and Ca content and by decreasing bulk density and P concentration in a farm soil with P concentration above the agronomic recommended value. Crop biomass and yield averages increased with increasing dredged sediment ratios. Nutrient loss (P and N) in the percolated solutions from the soil blends showed no significant changes when compared to the percolated solutions in the 100% farm soil treatment, indicating no significant contribution to the export of nutrients in percolated water.

Fecal sterols as sewage contamination indicators in Brazilian mangroves

Recent sewage contamination in Brazilian mangrove forests was evaluated using fecal sterols as biomarkers and socioeconomic indicators. The sterols were quantified by gas chromatography/mass spectrometry (GC/MS). Total fecal sterol concentrations ranged between 2.50 2.50 and 39.03 μg g−1 and coprostanol, between 0.23 and 6.97 μg g−1. Mangroves located in less urbanized regions presented low coprostanol levels and low coprostanol/cholesterol and (5β/5β + 5α) stanol ratios in sediment, while urban mangrove forests presented moderate fecal contamination. In the latter, an intense contribution of untreated domestic effluents associated to metropolitan areas was noted, leading to a significant correlation between coprostanol concentrations and inadequate sanitation, reflecting environmental problems associated to disorderly urbanization processes coupled to the absence of an adequate urban infrastructure. However, even in metropolitan areas, fecal sterol levels did not reach those of highly contaminated regions, probably due to the intense and accelerated degradation process typical of tropical environments. However, this study highlights the importance of fecal contamination assessment in mangrove areas since the presence of untreated sewage in these ecosystems is an issue of public and environmental health.

Carbon and nitrogen deposition on the surface of marginal sediments under different land use systems along the Paraopeba river basin (Minas Gerais, State)

The knowledge of the contents of organic compounds in aquatic ecosystems is of great importance, since the dissolved organic matter represents a dynamic component in the interaction between geospheres. The objective of this study was to evaluate the levels of carbon, nitrogen, and carbon-to-nitrogen ratio in the marginal sediments and the carbon content in the waters along the Paraopeba river basin (MG). The samples were collected in five locations (Jeceaba, Brumadinho, Fortuna de Minas, Florestal, and Três Marias) corresponding to the high, medium, and low river segments. The carbon content was determined by the Walkley &amp; Black method and the nitrogen content by the Kjeldahl method. The carbon content ranges from 4.75 to 5.97 g kg-1. Nitrogen ranged from 0.73 to 1.08 g kg-1. Finally, the carbon-to-nitrogen ratio varied from 5.15 to 21.25. The carbon content in the water samples ranged from 0 to 0.25 g L-1. As the values ​​of dissolved organic carbon were very low or even zero, the nitrogen content and the carbon-to-nitrogen ratio were not determined. There was a negative and a positive correlation with the aluminum content (r = -0.70 and r = 0.74, respectively) indicating possible contamination by heavy metals. Therefore, the levels of carbon, nitrogen, and the carbon-to-nitrogen ratio were sensitive indicators of changes in the aquatic ecosystem.

Abundance and diversity of diazotrophs in the surface sediments of Kongsfjorden, an Arctic fjord

Diazotrophy in the Arctic environment is poorly understood compared to tropical and subtropical regions. Hence in this study, we report the abundance and diversity of diazotrophs in Arctic fjord sediments and elucidate the role of environmental factors on the distribution of diazotrophs. The study was conducted during the boreal summer in the Kongsfjorden, an Arctic fjord situated in the western coast of Spitsbergen. The abundance of nifH gene was measured through quantitative real-time PCR and the diversity of diazotrophs was assessed by nifH targeted clone library and next generation sequence analysis. Results revealed that the abundance of nifH gene in the surface sediments ranged from 2.3 × 106 to 3.7 × 107 copies g- 1. The δ-proteobacterial diazotrophs (71% of total sequence) were the dominant class observed in this study. Major genera retrieved from the sequence analysis were Desulfovibrionaceae (25% of total sequence), Desulfuromonadaceae (18% of total sequence) and Desulfobacteriaceae (10% of total sequence); these are important diazotrophic iron and sulfur-reducing bacterial clade in the Kongsfjorden sediments. The abundance of nifH gene showed a significant positive correlation TOC/TN ratio (r2 = 0.96, p ≤ 0.05) and total organic carbon (p ≤ 0.05) content in the fjord sediments. The higher TOC/TN ratio (4.24-14.5) indicated low nitrogen content organic matter in the fjord sediments through glacier runoff, which enhances the abundance and diversity of nitrogen fixing microorganisms.

Effect of Compound Surfactants Modified Carbonyl Iron on Magnetorheological Fluids

As a fast-responding, intelligent, and controllable fluid material, magnetorheological fluid has drawn considerable attention. However, undesirable sedimentation severely restricts its wide application. To solve this problem, an improved strategy is proposed to prepare the magnetorheological fluid with great sedimentation stability. In this study, we used the compound surfactants to modify carbonyl iron powder and fumed silica as a thixotropic agent. At the same time, the effect of different contents of fumed silica on the rheological properties of MRF was studied. The scanning electron microscope, sedimentation, and rheological tests showed that fumed silica can significantly improve the sedimentation stability of magnetorheological fluids, and compound surfactants can increase its dispersion in magnetorheological fluids. As for the fumed silica (1.85 wt%) MR fluid, the sedimentation ratio is about 92.4% in the testing period of 58 days, indicating more excellent sedimentation stability compared to the commercial MR fluid (87.6%). When the magnetic field strength is beyond 391 kA/m, the shear stress is better than commercial magnetorheological fluid.

Mobility of carbohydrates, proteins, phenol and eutrophication assessment in a brackish Egyptian lake; predicted equations

ABSTRACT Although great efforts have been devoted in assessing the ecological risks in aquatic environments, a lack of information is still present. An integrative approach was proposed concerning the mobility of carbohydrates, proteins and phenol among water, sediments and macrophytes in relation to the physical, chemical and geochemical parameters of Lake Mariout. Total carbohydrates, proteins and phenol showed averages of 6.80 mg L−1, 116.90 mg L−1 and 19.46 µg L−1; 89.82 mg g−1; 29.21 mg g−1 and 1.80 µgg−1; and 60.80 mg g−1, 15.27 mg g−1 and 9.29 mg g−1 in water, sediments and macrophytes, respectively. Protein/carbohydrate ratios in sediments were used as the trophic indicator. This study cleared out that all stations had ratios (<1) refereeing to aged organic matter. Station 6 indicated fresh organic matter. Moreover, the ratio of total organic carbon to total nitrogen (TOC/TN) suggested a primarily marine origin at eleven stations (<10) and a mixture of terrestrial input and marine materials (>10) at stations 1 and 7 located in the North-West Basin. Relatively high phenol concentrations of 54.5, 38.25 and 45.37 µgL−1 in water were measured at stations (3 & 5) located in the Main Basin, and station 11 located at El-Qalaa drain, respectively. The partition coefficient of phenol (Kd) varied from 0.053 to 0.199 (<1 Lg−1) revealing high mobility and an underground disposal facility. The low biodiversity of phytoplankton (38 spp.), seagrasses (4 spp.) and seaweed (3 spp.) inside the lake reflected the impact of wastewater discharged. Two phytoplankton blooms were observed at stations 3 and 7. According to the Diversity Index of Boyd, all Mariout stations (<4) are moderately polluted. Multivariate analyses were adopted to describe the lake chemistry. This study gives a conceptual framework helps decision-makers to express the problem of sustainability at Lake Mariout.

堆積物の亜鉛同位体比に基づく宍道湖の亜鉛汚染源の考察

堆積物の亜鉛同位体比に基づく宍道湖の亜鉛汚染源の考察

Micron-Nanometer Evaporite Mineral Compositions in the Jiangling Depression, Jianghan Basin, China, by Means of Scanning Electron Microscopy.

Scanning electron microscopy (SEM) was used to analyze and study micron-nanometer evaporite samples collected from Paleocene and Eocene drill cores in the Jiangling Depression. Accordingly, seven beds of potassium-bearing solid rocks were accurately identified. Sylvite, carnallite, syngenite, dolomite, thenardite, anhydrite, glauberite, halite, barite, celestite, and other solid salt minerals were found, and carnallite, syngenite, and thenardite were found for the first time in the Jiangling Depression. Sylvite, syngenite, and carnallite indicate that the Paleogene salt lakes in the Jiangling Depression had evolved to the sylvite stage and that prospecting for solid sylvite would be satisfactory. Micron-nanometer celestite is contained in the evaporites, from which we can infer that strontium may have been provided by deep formation water (or oil-field water). This finding is of great significance to studying the genesis of sylvite sediment in the Jiangling Depression. From the extensive development of primary glauberite beds typical of warm salt minerals in the Shashi Formation, it can be inferred that the late Paleogene paleoclimate in the Jiangling Depression of the Jianghan Basin was dry and hot. Based on the extensive distribution of micron-nanometer pyrite, siderite, iron and Fe₂O₃/FeO ratios in evaporite sediments and color analysis of mudstones, the evaporites in the study area formed in an underwater anoxic, reducing environment during sedimentation. Therefore, the evaporite sediments in the Paleocene-Eocene interval of the Jiangling Depression are proposed to have formed in a saltwater lake sedimentary environment, and the ancient lake was characterized by a deep-water salt lake sedimentary model.

Sand Grain Size and Organic Matter Concentration in the Intertidal Zones on the Southwest Coast of Taiwan

From April 2013 to April 2014, the average pH and water temperature of the Taisi oyster cultivation area (TS, Yunlin County, Taiwan) were 8.05 (7.35 - 8.45) and 24.7˚C (13.7˚C - 32.8˚C) (N = 8226) The average organic matter (OM) concentration at sites TS-A and TS-B were 6.9% ± 1.3% and 6.9% ± 1.2%, and the weight of drift sand was 40.3 ± 19.1 g/d/m2 and 28.5 ± 34.3 g/d/m2 (N = 27). Considerable sand drifting typically occurs during the southwest monsoon season in summer. The average OM concentration at five dunes from Zhuoshui estuary to Zengwun estuary was 23.9 ± 4.5 g/kg. The percentage of sand grain weight of 0.15 - 0.25 mm and 0.25 - 0.60 mm was 82.5% ± 14.2% and 10.5% ± 12.0%. In the spring and autumn of 2015, the average OM concentration at the eight intertidal zones from Hanbao to Cigu was 49.8 ± 34.1 g/kg (N = 177), and the OM concentrations at Huwei estuary and Hanbao and Fangyuan intertidal zones were relatively high. The OM concentration (95.3 ± 75.7 g/kg) of the low tide zone of Huwei estuary was the highest among all tidal zones. The OM concentration during spring (59.4 ± 41.7 g/kg, N = 95) was higher than that in autumn (39.1 ± 17.8 g/kg, N = 84). For sand grain size ranges 0.15 - 0.25 and 0.063 - 0.15 mm, the weight ratio of intertidal sediment was 39.4% ± 26.9% and 27.6% ± 20.1%, respectively. The broad and flat intertidal zone was marked by fine sand and long intertidal zone; the weight ratio of SGSs < 0.25 mm exceeded 65%, and the OM concentration was between 20 and 30 g/kg. Coastal habitat diversity creates differences in biological communities, especially among crabs and benthic organisms. A greater understanding of coastal environments can aid in the management of coastal wetlands.