Bottom Samples Research Articles

Morphosedimentological features of the sea floor in the outer sector of the Bahia Blanca estuary, Argentina

The purpose of this paper is to analyze the morphology of the Quaternary relict features and bedforms that characterize the outer zone of an extensive mesomareal system, which is part of the Bahía Blanca estuary (Argentina), and to estimate the prevailing hydro-sedimentological conditions on the continental shelf adjacent to the estuary. Surveys with a multibeam bathymetric system, side-scan sonar and a high-resolution seismic system (3.5 kHz) were carried out and bottom sediment samples were collected. In general, the seafloor presents a varied configuration, marked by changes in its physiography. The Quaternary relict features are composed of two terraces (12–14 m and 18–22 m deep), with steeply sloping escarpments, that are oriented approximately parallel to the current coastline. Associated with these terraces, wide abrasion platforms develop with irregular and plateau-like structures up to 4 m high, together with large rocky blocks up to 6 m in diameter. Here, the predominant sediment corresponds to a gravel-sized material composed of quartzite boulders, siltstone fragments of up to 7 cm, and biogenic remains with different degrees of fragmentation. These sedimentological data, together with the bathymetric and seismostratigraphic information, indicate that the terraces and abrasion platforms are ancient shorelines that originated in an environment with high wave energy, corresponding to periods of stabilization of sea level rise during the final stage of the last postglacial transgression (late Pleistocene-Early Holocene). On the other hand, asymmetric dunes of different sizes (0.5 m < height < 5 m, 5 m < wavelength < 200 m), sand ribbons (length > 300 m) and comet marks originated in equilibrium with the present-day hydro-sedimentological conditions. The availability of sandy material mobilized as bedload is the determining factor for the generation of the varied bedforms. Thus, sand ribbons and comet marks are generated especially in the northern sector of the area, with mobile sediment thicknesses ≤ 0.5 m. With larger thicknesses the formation of dunes occurs. Their size and asymmetry show an intense transport of sand as bedload towards the continental shelf, the southern sector of the area being the main route of the sediment that leaves the estuary. This sediment is the supply source of the sandy shoals that are part of the great ebb delta developed on the continental shelf in the external area of the Bahía Blanca estuary.

A strontium isoscape of inland southeastern Australia

Abstract. The values and distribution patterns of the strontium (Sr) isotope ratio 87Sr/86Sr in Earth surface materials are of use in the geological, environmental, and social sciences. Ultimately, the 87Sr/86Sr ratios of soils and everything that lives in and on them are inherited from the rocks that are the parent materials of the soil's components. In Australia, there are few large-scale surveys of 87Sr/86Sr available, and here we report on a new, low-density dataset using 112 catchment outlet (floodplain) sediment samples covering 529 000 km2 of inland southeastern Australia (South Australia, New South Wales, Victoria). The coarse (&lt;2 mm) fraction of bottom sediment samples (depth ∼ 0.6–0.8 m) from the National Geochemical Survey of Australia were milled and fully digested before Sr separation by chromatography and 87Sr/86Sr determination by multicollector-inductively coupled plasma mass spectrometry. The results show a wide range of 87Sr/86Sr values from a minimum of 0.7089 to a maximum of 0.7511 (range 0.0422). The median 87Sr/86Sr (± median absolute deviation) is 0.7199 (± 0.0071), and the mean (± standard deviation) is 0.7220 (± 0.0106). The spatial patterns of the Sr isoscape observed are described and attributed to various geological sources and processes. Of note are the elevated (radiogenic) values (≥∼ 0.7270; top quartile) contributed by (1) the Palaeozoic sedimentary country rock and (mostly felsic) igneous intrusions of the Lachlan geological region to the east of the study area; (2) the Palaeoproterozoic metamorphic rocks of the central Broken Hill region; both these sources contribute radiogenic material mainly by fluvial processes; and (3) the Proterozoic to Palaeozoic rocks of the Kanmantoo, Adelaide, Gawler, and Painter geological regions to the west of the area; these sources contribute radiogenic material mainly by aeolian processes. Regions of low 87Sr/86Sr (≤∼ 0.7130; bottom quartile) belong mainly to (1) a few central Murray Basin catchments; (2) some Darling Basin catchments in the northeast; and (3) a few Eromanga geological region-influenced catchments in the northwest of the study area; these sources contribute unradiogenic material mainly by fluvial processes. The new spatial Sr isotope dataset for the DCD (Darling–Curnamona–Delamerian) region is publicly available (de Caritat et al., 2022; https://dx.doi.org/10.26186/146397)​​​​​​​.

Study of the Physicochemical and Biological Properties of the Lipid Complex of Marine Microalgae Isolated from the Coastal Areas of the Eastern Water Area of the Baltic Sea.

The Baltic Sea algae species composition includes marine euryhaline, freshwater euryhaline, and true brackish water forms. This study aimed to isolate a lipid–pigment complex from microalgae of the Baltic Sea (Kaliningrad region) and investigate its antimicrobial activity against Gram-positive and Gram-negative bacteria. Microalgae were sampled using a box-shaped bottom sampler. Sequencing was used for identification. Spectroscopy and chromatography with mass spectroscopy were used to study the properties of microalgae. Antibiotic activity was determined by the disc diffusion test. Lipids were extracted using the Folch method. Analysis of the results demonstrated the presence of antimicrobial activity of the lipid–pigment complex of microalgae against E. coli (the zone diameter was 17.0 ± 0.47 mm and 17.0 ± 0.21 mm in Chlorella vulgaris and Arthrospira platensis, respectively) and Bacillus pumilus (maximum inhibition diameter 16.0 ± 0.27 mm in C. vulgaris and 16.0 ± 0.22 mm in A. platensis). The cytotoxic and antioxidant activities of the lipid complexes of microalgae C. vulgaris and A. platensis were established and their physicochemical properties and fatty acid composition were studied. The results demonstrated that the lipid–pigment complex under experimental conditions was the most effective against P. pentosaceus among Gram-positive bacteria. Antimicrobial activity is directly related to the concentration of the lipid–pigment complex. The presence of antibacterial activity in microalgae lipid–pigment complexes opens the door to the development of alternative natural preparations for the prevention of microbial contamination of feed. Because of their biological activity, Baltic Sea microalgae can be used as an alternative to banned antibiotics in a variety of fields, including agriculture, medicine, cosmetology, and food preservation.

Effects of increasing chlorine concentration in feedstock on the emission and distribution characteristic of dioxins in circular fluidized bed boiler.

Field studies were conducted to study the emission and distribution characteristics of dioxins by elevating the chlorine concentration in feedstock in a circular fluidized bed boiler. The concentration and total equivalent quantity of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in all flue gas, electrostatic ash, bag filter ash, and bottom ash samples under blank condition (i.e., feedstock was normal coal) and chlorine labeling condition (i.e., feedstock mixed with coal and chlorine-containing labeling agent) were analyzed. Results illustrated that the concentration of PCDD/Fs in all gaseous and ash samples increased with the addition of chlorine in feedstock, with the largest and least increment in dioxin concentration observed in electrostatic ash and flue gas. PCDDs were the predominate congeners in flue gas, accounted for 50.1-60.4% of the total PCDD/F concentration under chlorine labeling and blank conditions, while PCDD/F distribution changed from PCDD- to PCDF-predominate by increasing chlorine content in feedstock under all field test conditions: 46.6-92.9%, 34.0-76.1%, and 47.0-53.1% of PCDFs were distributed in electrostatic ash, bag filter ash, and bottom ash, respectively. Highly chlorinated PCDD/F congeners such as O8CDD/F and 1,2,3,4,6,7,8-H7CDD/F were the primary contributors to dioxin concentration in flue gas and bottom ash samples, whereas low-chlorinated 2,3,7,8-T4CDF and 1,2,3,7,8-P5CDF congeners became critically dominating in electrostatic and bag filter ash.

Immobilisation of metals from bottom sediments using two additives and thermal treatment

A major problem associated with the land-based management of bottom sediments is their contamination with metals. The aims of the study were: 1) to use two additives for the immobilisation of metals; and 2) to evaluate the effect of three combustion temperatures on metal content and bottom sediment properties. The mixtures were prepared using contaminated bottom sediment and the following waste materials: cellulosic waste and biomass ash. In the second experiment, the bottom sediment samples were subjected to a thermal process, and three temperatures were chosen 500/800/950 °C. Overall, the addition of cellulosic waste and biomass ash to acidic, metal-contaminated bottom sediments significantly improved the properties of the resulting mixtures, including an increase in the pH value, sorption capacity, macronutrient content, and a decrease in the content and mobility of metals (Cd, Zn, Pb, Cr). The study confirmed the effectiveness of the thermal process on a significant reduction in the ecotoxicity of the sediments, a reduction in total content of elements, and a decrease in their leachability, and thus mobility, with increasing process temperature. The study results revealed that the converted contaminated bottom sediments can be effectively managed, provided that further studies on their technical application are carried out.

Microbulbifer okhotskensis sp. nov., isolated from a deep bottom sediment of the Okhotsk Sea.

A Gram-negative, aerobic, non-motile bacterium КMM 9862T was isolated from a deep bottom sediment sample obtained from the Okhotsk Sea, Russia. Based on the 16S rRNA gene and whole genome sequences analyses the novel strain КMM 9862T fell into the genus Microbulbifer (class Gammaproteobacteria) sharing the highest 16S rRNA gene sequence similarities of 97.4% to Microbulbifer echini AM134T and Microbulbifer epialgicus F-104T, 97.3% to Microbulbifer pacificus SPO729T, 97.1% to Microbulbifer variabilis ATCC 700307T, and similarity values of < 97.1% to other recognized Microbulbifer species. The average nucleotide identity and digital DNA-DNA hybridization values between strain КMM 9862T and M. variabilis ATCC 700307T and M. thermotolerans DSM 19189T were 80.34 and 77.72%, and 20.2 and 19.0%, respectively. Strain КMM 9862T contained Q-8 as the predominant ubiquinone and C16:0, C16:1 ω7c, C12:0, and C10:0 3-OH as the major fatty acids. The polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine, an unidentified aminophospholipid, an unidentified aminolipid, two unidentified phospholipids, phosphatidic acid, and an unidentified lipid. The DNA G+C content of 49.8% was calculated from the genome sequence. On the basis of the phylogenetic evidence and distinctive phenotypic characteristics, the marine bacterium KMM 9862T is proposed to be classified as a novel species Microbulbifer okhotskensis sp. nov. The type strain of the species is strain KMM 9862T (= KACC 22804T).

Mechanical activation improves reactivity and reduces leaching of municipal solid waste incineration (MSWI) bottom ash in cement hydration system

This laboratory study explores the effects of mechanical activation on the properties of municipal solid waste incineration (MSWI) bottom ash (BA) in a cement hydration system. The experimental results showed that the mechanical activation effectively reduced the particle size of municipal solid waste incineration bottom ash (MSWIBA), increased its specific surface area by about 770%, 1674%, and 1990%, and improved the 28d compressive strength of bottom ash-cement paste samples by about 5%, 14%, and 8% after milling of 15min, 30min, and 45min, respectively. The scanning electron microscopy revealed that the microstructure of the 30min-milled bottom ash-cement sample was more homogenous than other samples, which likely accounted for the difference in compressive strength. X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis were employed to shed light on the process, products, and degree of hydration of bottom ash-cement pastes. In addition, the leachate toxicity of heavy metals was evaluated and the 30min-milled bottom ash-cement paste showed the best binding effect in reducing the leaching of heavy metals. This work demonstrates the great potential of using mechanical-activated MSWI bottom ash as a supplementary cementitious material with acceptable environmental footprint.

Identification of geochemical anomalies associated with Sn-W mineralization in the Dong Van region, North-Eastern Vietnam, using statistical methods

Sn-W multimetal mineralization in the Dong Van region, North-Eastern Vietnam was studied using statistical and multivariate approaches based on 890 samples of stream bottom sediments collected for assaying for 27 elements. The findings of frequency analysis demonstrated that Pb, As, Bi, Li, Sn, W, Ta, Ce, Ag, Sb, and Be have close ties with multimetal ores, implying that these elements can be used as prospecting indicators for multimetal mineralization. In addition, correlation matrix and dendrogram studies were also applied to subdivide the elements in the stream bottom sediment samples assays into two groups: associated with multimetal mineralization (Be-Sn-W-Bi, and, to a lesser extent, Li-Pb sub-groups) and not associated with the mineralization: (As-Cd-Sc-Cr-Ce-La, Co-Ni-V, and Ga-Ge-Ba sub-groups). Sn and W were found to be the best indicator elements for the mineralization, according to the findings of geochemical modeling and location of their anomalies in the region. Furthermore, extensive Sn and W anomalies were identified in the Dong Van region (using threshold values (mean ± 3 STD), providing the most important indications for multimetal mineralization prospecting in the region. The studies also suggest genetic ties between the region’s multimetal mineralization and the northwest-southeast fault system and concealed granitoid blocks. Finally, the performed statistical analyses (with the use of threshold values) of stream bottom sediments assays allowed revealing indicator elements and their geochemical anomalies and using them as an effective tool in further prospecting and exploration for multimetal mineralization in the region.

Chemical Forms and Spatial Distribution of Phosphorus in the Sediment of Sihe River

Based on the study of the content, forms, and spatial distribution of phosphorus (P) in the surface and columnar sediments of the Sihe River, the relationships between the total phosphorus (TP) and various forms of P and the basic physical and chemical properties of sediment and their ecological significance were deeply discussed. The forms of P in the sediment were defined including soluble and loosely bound P (S/L-P), Al-bound P (Al-P), Fe-bound P (Fe-P), reductant soluble P (RS-P), Ca-bound P (Ca-P), and residual P (RES-P) using the method of selectively sequential extraction. The results indicated that ω (TP) was 421.84-1188.65 mg·kg-1 in the surface sediment. Among the six forms of P, the content of Ca-P was the highest, accounting for more than 40% of TP, followed by the content of Fe-P, accounting for more than 20% of TP. The content of S/L-P was the lowest, which only accounted for approximately 0.4% of TP. The contents of TP and various forms of P in the surface sediments of the downstream area of the Sihe River were higher than those of the upstream area of the river, which was induced by the discharge of industrial wastewater and domestic sewage in the urban areas nearby the downstream portion of the Sihe River. The contents of TP in the upper samples of the two sediment profiles were obviously higher than those in the bottom samples, indicating that the P pollution in the water environment of the Sihe River has been intensifying in recent years. Among all forms of P in the sediment profiles, Ca-P accounted for the largest proportion, followed by Res-P. The correlation analysis results showed that significant correlations were observed between Fe and Fe-P, Al and Al-P, Ca and Ca-P, and TOC and RS-P in the surface sediments; the same correlations had not been found in the sediment profiles. The calculated results of Fe and TP molar ratio indicated that the sediments of the Sihe River could further accumulate P. The percentage of bioavailable P (BAP) in sediment was 25%-50%.

Late Paleozoic Tectonic Evolution of the Qinling Orogenic Belt: Constraints of Detrital Zircon U-Pb Ages from the Southern Margin of North China Block

The tectonic evolution of the Qinling Orogenic Belt in the Late Paleozoic has long been controversial, especially due to the limitation of the Mianlue Ocean subduction time. Basin formation and sedimentary development in the southern North China Block are closely related to the tectonic evolution of the Qinling Orogenic Belt, which is an effective entry point to study basin–mountain interaction. We present new detrital zircon U–Pb data from the Shihezi Formation in the Luonan area in the southern margin of the North China Block. The results show that the bottom sample has two major peaks at 288 Ma and 448 Ma, with weak peaks at 908, 1912 Ma and 2420 Ma. The top sample has one major peak at 297 Ma, with weak peaks at 1933 Ma and 2522 Ma. Combined with the published paleocurrent data and lithofacies paleogeography, the sediments of the bottom sample were sourced from the North Qinling Belt, Inner Mongolia Palaeo-Uplift and the basement of the North China Block. The top sample originated mainly from the Inner Mongolia Palaeo-Uplift and the basement of the North China Block. Comparing the obtained zircon U-Pb ages with the published relevant data in the North China Block, it is found that the provenance area shifted from the Qinling Orogenic Belt to the Inner Mongolia Paleo-Uplift in the Late Carboniferous–Permian, and the Qinling Orogenic Belt could hardly provide provenance for the southern North China Block in the Middle Permian. The uplift of the Qinling Orogenic Belt in the Late Carboniferous may be the continuation of Caledonian orogeny in the Early Paleozoic, whereas the uplift of the Inner Mongolia Palaeo-Uplift is related to the tectonic evolution of the Central Asian Orogenic Belt during the Late Paleozoic. This tectonic transformation occurred when the Qinling Orogenic Belt no longer supplied sediments to the southern North China Block in the Middle Permian, and the Mianlue Ocean subduction did not occur until at least the Late Permian.

Effect of the Spatial Arrangement of Floating Builds with Minimum Support on the Microstructural and Mechanical Characteristics of Electron Beam Additively Manufactured Biomedical Ti-6Al-4V Alloys.

In this study, normal and floating builds of Ti-6Al-4V were fabricated by electron beam additive manufacturing. The effects of the spatial arrangement on the microstructure, mechanical properties, and surface roughness of the parts were investigated. Both the normal and floating builds exhibited an α+β lamellar microstructure, but the normal builds had finer grains compared to the floating builds. The microstructural characteristics were correlated with the thermal history, specifically the cooling rate, resulting from the connection plate (S45C for the normal builds and the powder bed for the floating builds). The compressive yield strength and hardness of the normal builds were higher than those of the floating builds, regardless of build location owing to the grain refinement effects on the normal builds. The top surface (TS) of the sample was smoothest, and the lateral surface of the sample was the roughest for both the normal and floating builds; however, the roughness of the TS and bottom surface samples did not differ significantly between normal and floating builds. There were no noticeable differences in the microstructure and mechanical properties of the builds in five different positions, that is, the center and four corners. Finally, these findings were used to develop a set of conceptual spatial arrangement designs, including floating builds, to optimize the microstructure and mechanical properties.

ROLE OF ENVIRONMENTAL PARAMETERS IN THE DISTRIBUTION OF MEIOBENTHIC FAUNA (OSTRACODA AND FORAMINIFERA) IN THE ROMANIAN BLACK SEA SHELF

With limited research undertaken on the distribution and biodiversity of meiobenthic fauna (living Ostracoda and Foraminifera) in the Black Sea, the present study has focused to create the baseline data for the Romanian Black Sea continental shelf. For this purpose, 9 short core samples were collected using a multi-corer in water depth ranging from 27.8 m to 41.8 m in May 2018 around the Sf. Gheorghe area (map sheet L35-120B). A total of 14 species were found belonging to Ostracoda (7 families), Cercozoa (one family), Foraminifera (5 families). The highest density of meiobenthic species was correlated with the highest concentration of CaCO3 where the substrate is dominated by a clayey silt or sandy silt while TOC concentrations were negatively correlated with the low densities occurring in the western part of the perimeter silt clay substrate is found. The density of soft-shelled foraminifera has a positive correlation with the concentration of salinity in the bottom water samples, and depth and a negative correlation with the bottom water temperature. The density of Ostracoda has a positive correlation with temperature and depth but a negative correlation with salinity in the bottom water samples. The relationships between high concentrations of CaCO3and increased abundances of meiobenthic fauna and high concentrations of TOC and low meiofauna abundances, respectively, reinforce the hypothesis according to which the dispersal of meiofaunal species is strongly influenced by environmental gradients. The data collected from Romanian Black Sea Shelf (Sf. Gheorghe Area) in the perimeter of the map sheet L35-120B, suggest another record of soft shelled monothalamous Foraminifera and Gromiidae group.

Separated from the cradle: A new species of Falcidens (Mollusca, Aplacophora, Caudofoveata) reveals weird patterns of distribution in the deep-sea

The shell-less, worm-like caudofoveate aplacophorans are common inhabitants of the deep-sea. A recent series of studies has demonstrated their phylogenetic, ecological and biogeographical importance for the understanding of marine environments. Falcidens Salvini-Plawen, 1968 is among the most speciose genera of Caudofoveata, including species with a wide range of morphological diversity. Here, F. amiae sp. nov. is described based on its body shape, sclerites, and radula; it is compared with other similar species, and distributions are also modelled to envisage other suitable areas of occurrence. Collected over a large area of the southwestern Atlantic Ocean, along the Brazilian coast, most specimens were found in bottom samples from the upper continental slope. Falcidens amiae sp. nov. has a stoutish body without externally perceptible divisions, a “U”-shaped oral shield, a radula with two pairs of teeth, and sclerites with a wide base and acute blade ornamented with a strong central longitudinal keel and weak grooves. While almost all species of Falcidens have elongated bodies with externally perceptible divisions, only two known species have a more-stoutish and homogeneous body shape, F. limifossorides Salvini-Plawen, 1992 and F. halanychi Schander, Scheltema and Ivanov, 2004, comparable to that of F. amiae sp. nov.; they are also similar in the radula structure and F. amiae sp. nov. has an oral shield and sclerites that are markedly similar to those of F. limifossorides. These taxa appear to form a clade, but if so, they apparently became separated long ago, as they now have very distinct distributions. Maps of potential distributions showed that F. amiae sp. nov. and F. halanychi do not overlap in the Atlantic. This study fills a small gap in knowledge of the morphology of this intriguing molluscan group, revealing part of its puzzling distribution in the deep sea.

Challenges in double-beam laser interferometry measurements of fully released piezoelectric films

When utilizing double-beam laser interferometry to assess the piezoelectric coefficient of a film on a substrate, probing both top and bottom sample surfaces is expected to correct the erroneous bending contribution by canceling the additional path length from the sample height change. However, when the bending deformation becomes extensive and uncontrolled, as in the case of membranes or fully released piezoelectric films, the double-beam setup can no longer account for the artifacts, thus resulting in inflated film displacement data and implausibly large piezoelectric coefficient values. This work serves to identify these challenges by demonstrating d33,f measurements of fully released PZT films using a commercial double-beam laser interferometer. For a 1 μm thick randomly oriented PZT film on a 10 μm thick polyimide substrate, a large apparent d33,f of 9500 pm/V was measured. The source of error was presumably a distorted interference pattern due to the erroneous phase shift of the measurement laser beam caused by extensive deformation of the released sample structure. This effect has unfortunately been mistaken as enhanced piezoelectric responses by some reports in the literature. Finite element models demonstrate that bending, laser beam alignment, and the offset between the support structure and the electrode under test have a strong influence on the apparent film d33,f.

Establishment and application of a TaqMan probe-based qPCR for the detection of Enterocytozoon hepatopenaei in shrimp Litopenaeus vannamei.

Enterocytozoon hepatopenaei (EHP) is a common parasite that invades the epithelial cytoplasm in the hepatopancreas of shrimp Litopenaeus vannamei and results in slow growth of the host shrimps to cause significant economic loss in shrimp aquaculture. In this study, a TaqMan probe-based qPCR for quantitative detection of EHP was established. A pair of specific primers and a TaqMan probe were designed based on the sequence of cysteine desulfurase gene (NFS1) of EHP. The standard curve between cycle threshold (Ct) and the logarithmic starting quantity (SQ) of the template was determined as Ct = - 3.231 lg (SQ) + 40.638, with a correlation coefficient (R2) of 0.998 and an amplification efficiency of 103.9%. The lower limit of quantification was 1.67 × 101 copies/μL for this TaqMan probe-based qPCR and 1.67 × 103 copies/μL for the conventional PCR. The TaqMan probe-based qPCR established in the research was 100 times more sensitive than the conventional PCR method. In addition, the results of clinical sample detection indicated that the present technique was efficient in detecting EHP in the hepatopancreas, feces, water, and pond bottom mud samples. Therefore, the established TaqMan probe-based qPCR is a suitable technique for detecting EHP in both shrimp and aquatic environment samples.

Assessment of the ecological state of the composition of surface waters and bottom sediments in the Yamalo-Nenets Autonomous Okrug

The article shows the results of analyzes of surface waters and bottom sediments of the Yamalo-Nenets Autonomous Okrug. The following rivers were selected as objects: the Ob, the Taz, the Pur, the Yuribei etc. Sampling was carried out near settlements Salekhard, Nadym, Salemal, Pitlyar etc. Water samples were analyzed for the content of: dissolved oxygen, chemical oxygen demand, concentrations of oil products, iron, copper, zinc, nickel, manganese, sulfate ions, bottom sediment samples - for pH values of water extract, content of oil products, sulfates, iron, nickel, chromium, manganese, copper, mercury, lead, zinc, cadmium. Excesses of concentrations of iron, manganese and copper (relative to standard values) were found in most water samples. Elevated levels of petroleum products, lead, chromium, zinc, nickel, iron, manganese and copper (compared to the approved background values) were detected in many bottom sediment samples.

Resource Assessment of Larimichthys crocea in the East China Sea Based on eDNA Analysis

Environmental DNA (eDNA) is a promising tool for rapid and noninvasive biomonitoring and resource assessment. Broadly, two main PCR-based strategies of biodiversity monitoring can be deployed for eDNA analysis. The first one consists of targeting single species using standard PCR, real-time quantitative PCR (qPCR), or droplet digital PCR (ddPCR). The second strategy aims to simultaneously detect multiple species relying on High-Throughput Sequencing (i.e. eDNA metabarcoding). The aim of this study was to further explore a convenient and feasible method to correctly assess fishery resources using eDNA technology for large yellow croaker (Larimichthys crocea). Two eDNA methods (metabarcoding and qPCR) were used to investigate the biomass and distribution of large yellow croaker in the autumn and spring seasons in the central and southern regions of the East China Sea, and these results were compared with the results of a bottom trawling fishery survey. The results suggested that the designed NADH2-specific primers and developed real-time qPCR method were more applicable and reliable. The variation in the eDNA concentration of large yellow croakers coincided well with that of a real capture survey in the East China Sea. The difference in eDNA concentration between the surface and bottom water samples reflected the distribution characteristics in the water layer related to the life history of L. crocea in the two seasons. The developed methods based on eDNA technology and real-time qPCR could not only be used to evaluate the resource distribution but could also contribute to estimating the life history and migration route of large yellow croaker.

Changes in the Dissolved Organic Matter Characteristics Released from Sediment According to Precipitation in the Namhan River with Weirs: A Laboratory Experiment.

In this study, changes in the properties of dissolved organic matter (DOM) released from sediments into water layers were investigated. To analyze the spatial and temporal variation in dissolved organic carbon (DOC), sediment and bottom water samples were collected upstream of the Gangcheon, Yeoju, and Ipo weirs of the Namhan River during the rainy and non-rainy seasons. The initial DOC was correlated with precipitation (R2 = 0.295, p = 0.034) and residence time (R2 = 0.275, p = 0.040). The change in the bottom water DOC concentration resulted from the DOC released from the sediments, which may cause water quality issues in the bottom water. The fluorescence analysis revealed that the DOM contained higher levels of hydrophilic and low-molecular-weight (LMW) organic matter in the non-rainy season and higher levels of hydrophobic and high-molecular-weight (HMW) organic matter in the rainy season. Since the Namhan River is the main resource of drinking water for the Seoul metropolitan area, our results can help to optimize the drinking water treatment process by reflecting the DOM characteristics that vary with the seasons. Furthermore, the statistical analysis confirmed that the nutrient content of pore-water and sediment can be used to estimate the DOM release rate from the sediment to the water layer. The results of this study provide a better understanding of DOM movement in aquatic ecosystems and the influences of rainfall on the water quality of the surface waterbody.

Mapping of Seafloor and Delineating Coral Reefs of Southern Iraq/Northwest Arabian Gulf by Side Scan Sonar Technique

High-resolution Side Scan Sonar data, under-water observation (video and photograph) and bottom samples (rocks and sediments) were integrated to map the seafloor of the Palinurus shoal which is one of the submerged shoal site in the Iraqi territorial marine, Northwest region of the Arabian Gulf. The Side Scan Sonar field survey was carried out along with eight parallel profile extending in SE-NW direction, at a length of 2.8 km for each line. Four backscatter patterns were mapped within the study area. The pattern reflects various seafloor lithology. The average depth of sea bottom was determined at 7 - 10 m. Coral Reefs were mainly found at two parts of the shoal site in the formed assemblages and sporadic in central and northern parts of the site respectively. These coral take different shapes, sizes and colors. Also, they are live in some places and dead in others.

The Effect of the Rock Slope Material on the Compressive Strength Value in Malino, South Sulawesi Province

The research location is on the upstream slope of the Jeneberang River in Malino, Gowa Regency, South Sulawesi. This study aims to determine the types of rocks the slopes and to study the relationship between mineralogy characteristics and rock mechanical properties. Mineralogical characteristics analysis used petrographic analysis, XRD and XRF, while for the analysis of rock mechanical properties using uniaxial compressive strength analysis in this study used three types of samples taken on the same slope with the top, middle and bottom sampling points. The results of this study indicate that the rock types found on the slopes are andesite igneous rock types with the same main mineral types, the mineral is albit, analcime, quartz and leucite, while the secondary minerals found in each sample are different, on the slopes of sample A the secondary mineral is spodumene, sample B secondary mineral is garnet and sample C is palygorskite. The value of the results of testing the mechanical properties of each sample is also different, the correlation of the three uniaxial compressive strength test values to the mineral composition of rock samples shows that the correlation of quartz minerals to the compressive strength value and young's modulus has a fairly high correlation value of 0,934 and 0,9798, the mineral correlation value to the poisson ratio indicates that the mineral leucite has high correlation value compared to other minerals.