10-m Depth Research Articles

EXTH-06. GLIOBLASTOMA PATIENT SPECIFIC TRANSCRIPTOME REMODELING IN RESPONSE TO MDM2 ANTAGONIST TREATMENT OF WILD-TYPE P53 CANCER STEM CELLS IS ASSOCIATED WITH SENSITIVITY AND STRATEGIES FOR COMBINATION THERAPY

Abstract Over 70% of glioblastomas are p53 wild-type and these patients could benefit from p53 reactivation treatment. Here we determined the sensitivity of a glioblastoma patient-derived cancer stem cells (CSCs) panel to three MDM2 antagonists (MDM2a) to test to what extent transcriptional reprogramming is affected by genomic background and correlates to response to acute treatment with MDM2 antagonists. IC50 concentrations and area above the curve (AAC) were measured from dose response curves obtained from 4 and 7-day treatment. The inhibitors were specific to wt-p53 CSCs, but these presented a wide range of sensitivity. Seven wt-p53 CSCs were treated RG7112 IC50 concentrations or DMSO control for 24h (n=4). RNA was isolated for Illumina Truseq stranded mRNA libraries sequenced at 30M depth. Quantified raw counts were processed using NOISeq R package to determine differentially expressed genes (DEG) between control and treated samples. In addition to the expected high representation of upregulated p53 targets in all cell lines, we observed significan cell specific transcriptome alterations, including enrichment of survival pathways, such as mTOR, ERK and NFkB in the less sensitive CSC lines, which did not readily correlate with the individual genomic landscapes. E2F targets, G2-M cell cycle check point and DNA-repair pathways were highly enriched in the downregulated genes. Combination of MDM2a with radiation treatment (RT) was synergistic to a subset of CSCs. As validation we found that MDM2a treatment was effective in sensitizing a resistant orthotopic mouse glioblastoma PDX to fractionated RT, with maximum efficacy when treatment started 24h prior to RT vs simultaneously (Log-rank Mantel-Cox test: p=0.0006 vs 0.0277). The integration of the treatment-mediated transcriptional patterns with differential sensibility to MDM2 antagonists and genomic landscape of the CSC panel provides a platform to identify targets for combination therapies, which is the most promising clinical application of the reactivation of wt-p53 in GBMs.

Evaluation of long-term spatio-temporal characteristics of water and nitrogen in the vadose zone and potential threats to groundwater under different irrigation strategies

Groundwater contamination by nitrate-nitrogen (NO3–N) under intensive agriculture is increasingly receiving worldwide attention. However, knowledge of the potential effects of different irrigation strategies coupled with nitrogen applications on groundwater under intensive agricultural practices remains a critical issue and a grand challenge due to the long transit time for NO3–N across the thick vadose zone. To close this knowledge gap, the calibrated RZWQM2 model was used to investigate long-term (1970–2070) water and NO3–N dynamics in the vadose zone and the potential threat of NO3–N pollution on groundwater under different irrigation strategies (35% of total available water-triggered, 100% filled irrigation (I35% TAW), 90-mm irrigation (I90 mm), and 150-mm irrigation (I150 mm)) and nitrogen applications (optimal and conventional high rates) for the maize-wheat rotation system in the Jinghui Canal irrigation area of the Guanzhong Plain in China. Results showed that mean groundwater recharge values were 43, 65, and 271 mm yr−1 under the I35% TAW, I90 mm, and I150 mm scenarios, respectively, with no significant effect on crop yields. Accumulated NO3–N was concentrated at the 10-m depth over the past 50 years and would be deeply transported to the 15-m and 20-m depths under the I35% TAW and I90 mm strategies, respectively, in the future 50 years. Accumulated NO3–N was concentrated uniformly at the 30-m depth for the I150 mm scenario, with NO3–N amounts of 85.8 and 26.9 kg ha−1 yr−1 leached into the groundwater (30 m) under the conventional and optimal nitrogen applications. Although groundwater at 8–10 m faced the risk of NO3–N pollution during the past 50 years, and groundwater at the deeper depths of 15–20 m could be threatened in the next 50 years under the I35% TAW and I90 mm strategies, the annual amount of NO3–N leaching into groundwater could be significantly reduced from 68.9 to 71.8 kg ha−1 to 10.3–12.7 kg ha−1 by applying more optimal amounts of nitrogen. The results of this study provide a straightforward understanding of long-term spatial and temporal characteristics of water and NO3–N in the vadose zone, and provide insight into possible methods for controlling irrigation application amounts that would prevent groundwater pollution from NO3–N in irrigated areas.

DEVELOPMENT OF UNDERWATER ROV (REMOTELY OPERATED VEHICLE) SYSTEMS AND MECHANISM

Remotely Operated Vehicle or abbreviated as ROV is an underwater explorer robot where the robot is controlled remotely by an operator using a remote control system. Water ecosystems certainly have various kinds of hazards that cause harm to divers, such as wild animals, waters contaminated with toxic waste, limited oxygen, and many other risks. Based on these problems, research was carried out, namely the Design and Development of Underwater ROV (Remotely Operated Vehicle) Mechanisms and Systems where the tool built is an underwater robot that uses 8 DC motors to be able to perform 12 types of movements under water. The final result obtained by the ROV is that it is able to perform all of these movements except for the right somersault and left somersault. The speed and direction of rotation of the motor is controlled by a device, namely the BTS7960 motor driver. This robot aims to measure pressure and temperature and capture images underwater to a depth of 4m. Pressure and temperature measurements were made using a BMP180 pressure sensor and a DS18B20 temperature sensor where the measurement results will be displayed on a 16x2 LCD. Based on the test results, the pressure sensor has an error rate of 3.6% and a temperature sensor of 0.34%. Images and videos are captured by a device, namely a CCTV camera where the device is connected to a laptop device as a monitor. The test produced results in the form of images and videos that were quite clear.

Effects of stratification and mixing on spatiotemporal dynamics and functional potential of microbial community in a subtropical large-deep reservoir driven by nutrients and ecological niche

Seasonal thermal stratification is a common environmental phenomenon in reservoir water bodies and an important research topic for deep water reservoirs. A thermally stratified reservoir is an ideal system for investigating the interaction between factors affecting the environment and microorganism communities under spatial–temporal variation. However, few studies have focused on the effects of water stratification and mixing periods in microbial communities and nitrogen conversion. Therefore, using metagenomic sequencing and quantitative polymerase chain reaction, we investigated the microbial diversity and function in the Xin'anjiang Reservoir during water stratification and mixing period. Principal component analysis indicated that the bacterial communities were mostly affected by water stratification, mainly at 10-m depths, whereas the archaea community was influenced by the entire water profile. The predominant archaeal phyla changed from Candidatus_Woesearchaeota and Euryarchaeota to Thaumarchaeota with the increasing water depth during water stratification. The stratified variations of the dominant archaeal phyla strongly reflected the seasonal changes and vertical gradient in water temperature, dissolved oxygen, and pH. Linear regression analysis indicated that variations in microbial composition altered the overall functional attributes of the communities, especially in the archaeal community. Regarding nitrogen metabolism across the whole reservoir, the number of nitrification and denitrification genes dropped in the same direction as the river flow in spring and summer, while the opposite trend was observed in autumn and winter. The functional genes of the water profiles in the transitional and lacustrine zones varied considerably except in winter. Additionally, the copies of nitrification-related genes were more during the stratification stage than during the mixing stage, whereas copies of denitrification-related genes showed the opposite trend. Overall, this study provides unique insights regarding the effects of seasonal stratification on the distribution and function of microorganisms in large-deep reservoirs, which should be considered when establishing guidelines for reservoirs management.

An Investigation of the Performance of the ANNMethod for Predicting the Base Shear and Overturning Moment Time-Series Datasets of an Offshore Jacket Structure

The primary purpose of the current study was to investigate the performance of artificial neural networks to predict the time series of the water surface level (WSL), base shear, and overturning moment using two types of ANN models: Nonlinear Autoregressive models with exogenous inputs (NARX) and Nonlinear Autoregressive models (NAR). After determining the suitable model, NARX, the possibility of predicting the time series of the base shear and the overturning moment data was investigated by considering the water surface level and time as the multivariable model inputs. A jacket model with a height of 4.55m was fabricated and tested in the 402m-long wave flume of the NIMALA marine laboratory. The jacket was tested at the water depth of 4m and subjected to random waves with a JONSWAP energy spectrum. Three input wave heights were chosen for the tests: 20cm, 23cm, and 28cm. The findings showed that using the NARX neural network is a convenient method to predict the base shear and overturning moment values based on the water surface level data as input values. Finally, after suitable neural network determination, using the NARX neural network, the correlation value (R) for calculating water surface level (WSL), Base Shear, and Overturning Moment were obtained as 0.994, 0.97, and 0.94, respectively.

Temperature and pressure propagation characteristics in multi-media interfaces of PVDF pressure sensor near underwater explosion source

In this paper, based on the self-made PVDF pressure sensor, the underwater explosion test of the emulsion explosive was performed to verify the measurement accuracy of the self-made PVDF pressure sensor and the feasibility of the pressure measurement near the explosive source. Then the single column emulsion explosive and gram-grade Al/PTFE underwater explosion experiment and numerical simulation were carried out, and the error between the experimental and numerical simulation results is small (The difference between the pressure peaks obtained from the emulsion explosive experiment and numerical simulation is about 25.07 MPa and the pressure decay trend is close; the peak difference in lane 1 obtained by Al/PTFE experiment and simulation is about 23 MPa, the second peak difference is about 0.8 MPa, the pressure decay trend after the second peak is close, and the shock wave arrival moment in experiment lags the numerical simulation by about 30μs), which verifies the reliability of the simulation model. Meanwhile, the numerical simulation of explosion at a depth of 10m below sea level was performed, the evolutionary law of the sensor and water pressure at 1–10 times the charge diameter is expounded, the variable rule of temperature during sensor response period is analyzed. The numerical simulation results show that the time-history curve of pressure includes two stages: bubble microjet and shock wave propagation, which the bubble microjet pressure can reach 10 GPa, and the sensor structure and shock wave pressure test will not be affected within the response period. The time history curves of shock wave pressure in experiments are basically the same by comparing with the simulation results of underwater pressure at the same position, and impact temperature rise will affect the measurement accuracy of PVDF film, but the lasting time of heat conduction in the PVDF sensor is longer than the response period of impact pressure, therefore the influence of heat conduction on the test accuracy can be ignored.

Life in a changing environment: dreissenids’ feeding response to different temperature

Invasive species have far-reaching consequences for whole ecosystems. The two dreissenids zebra and quagga mussels are two of the most successful invaders in aquatic systems. Quagga mussels can colonize deeper parts of a lake while zebra mussels prefer shallow areas. Both species show large variability in shell morphology, but only quagga mussels show a shallow and deep-water morphotype. The aim of this study is to investigate the depth adaptation of quagga mussels and the potential filtration advantage of the quagga mussel compared to the zebra mussel. We conducted common garden experiments, where we measured filtration rates at different temperatures of quagga mussels collected from different water depths and compared them to zebra mussel from 1m depth. We found filtration rates to be strongly temperature dependent, and in particular, lower at 4 °C. Overall, zebra mussels fed less than quaggas. Quagga mussels collected from 1 m depth fed more at higher temperature than quaggas from 30 and 60 m. We hypothesize that deep-water quagga mussels are less sensitive to lower temperature and/or constrained to modify filtration rates at higher temperatures.

Analysis of scanning systematic errors for airborne laser bathymetry.

For the Palmer mechanical scanning pattern of an airborne laser bathymetry system, the potential errors of the scanning system are analyzed, and the associated error model is derived. The model composes the description of laser rays, water surface fluctuations, and refraction, and introduces certain simplifications concerning the water surface and column. Based on the scanning error model, the impact of each error source on the vertical and horizontal positioning accuracy is investigated and established through a numerical simulation. The quantitative impacts of each inaccuracy on the coordinates of the laser footprints on the sea surface and bottom were calculated, with a height of 100m for the airborne platform and a water depth of 10m. To verify the correctness of the simulation results and the error model based on a theoretical analysis, experiments are utilized with the system that we developed. Both the simulation analysis and experimental results show that this method can effectively obtain the systematic errors. The outcomes of the error model and analysis will give the theoretical foundations for lowering the effect brought on by each error source in the compensation scanning system and improving the point cloud accuracy in the ensuing data processing.

Predicting Turbulent Vertical Velocity in the Ocean Surface Layer under Mixed Convective and Wind/Wave Forcing

Abstract Turbulence in the ocean surface layer is forced by a mixture of buoyancy, wind, and wave processes that evolves over time scales from the diurnal scale of buoyancy forcing, through storm time scales, to the annual cycle. This study seeks a predictor for root-mean-square w (rmsw), a time and surface layer average of turbulent vertical velocity w measured by bottom-mounted vertical-beam acoustic Doppler current profilers, in terms of concurrently measured surface forcing fields. Data used are from two coastal sites, one shallow (LEO, 15-m depth) and one deeper (R2, 26-m depth). The analysis demonstrates that it is possible to predict observed rmsw with a simple linear combination of two scale velocities, one the convective scale velocity familiar from the atmospheric literature, the other a scale velocity wS representing combined wind and wave effects. Three variants are considered for this latter scale velocity, the wind stress velocity alone and two forms using both and US, a Stokes velocity characteristic of the surface wave field. At both sites, the two-parameter fit using alone is least accurate, while fits using the other two variants are essentially indistinguishable. At both sites, the coefficient multiplying is the same, within error bounds, and within the range of previous observations. At the deeper site, the coefficient multiplying the wind/wave scale velocity wS is approximately half that at the shallow site, a difference here attributed to difference in wave character.

Hydrocarbons in size-fractionated plankton of the Mediterranean Sea (MERITE-HIPPOCAMPE campaign)

Aliphatic and polycyclic aromatic hydrocarbons (AHs and PAHs, respectively) were analyzed in the dissolved fraction (<0.7 μm) of surface water and in various particulate/planktonic size fractions (0.7–60, 60–200, 200–500 and 500–1000 μm) collected at the deep chlorophyll maximum, along a North-South transect in the Mediterranean Sea in spring 2019 (MERITE-HIPPOCAMPE campaign). Suspended particulate matter, biomass, total chlorophyll a, particulate organic carbon, C and N isotopic ratios, and lipid biomarkers were also determined to help characterizing the size-fractionated plankton and highlight the potential link with the content in AHs and PAHs in these size fractions. Ʃ28AH concentrations ranged 18–489 ng L−1 for water, 3.9–72 μg g−1 dry weight (dw) for the size fraction 0.7–60 μm, and 3.4–55 μg g−1 dw for the fractions 60–200, 200–500 and 500–1000 μm. AH molecular profiles revealed that they were mainly of biogenic origin. Ʃ14PAH concentrations were 0.9–16 ng L−1 for water, and Ʃ27PAH concentrations were 53–220 ng g−1 dw for the fraction 0.7–60 μm and 35–255 ng g−1 dw for the three higher fractions, phenanthrene being the most abundant compound in planktonic compartment. Two processes were evidenced concerning the PAH patterns, the bioreduction, i.e., the decrease in concentrations from the small size fractions (0.7–60 and 60–200 μm) to the higher ones (200–500 μm and 500–1000 μm), and the biodilution, i.e., the decrease in concentrations in plankton at higher suspended matter or biomass, especially for the 0.7–60 and 60–200-μm size fractions. We estimated the biological pump fluxes of Ʃ27PAHs below 100-m depth in the Western Mediterranean Sea at 15 ± 10 ng m−2 day−1, which is comparable to those previously reported in the South Pacific and Indian Ocean.

Filter media enhanced electrokinetic remediated crude oil contaminated soil: investigation of its engineering properties and its suitability for road construction

Research have shown how electrokinetic remediation (EKR) technology attempts to tackle the challenge of soil contamination by crude oil. However, the suitability of the resulting remediated soils for use in road construction have not been well reported. This work investigates the engineering properties of filter media enhanced electrokinetic remediated crude oil contaminated soil (COCS) with a view to ascertain its suitability for use in road construction by comparing the performance of charcoal and active carbon as filter materials. COCS collected at a depth of 1m from the Nigerian Pipeline and Storage Company, Kaduna was remediated by using graphite electrodes to pass 1V DC/cm across EKR setups enhanced by incorporating a 1cm thick charcoal and active carbon separately as filter materials across the setups. Average removal efficiencies of 81.4% and 84.6% were obtained against the 78,600 mg/kg oil content of the COCS from charcoal and active carbon filter media enhancements respectively. This showed that active carbon, with higher removal efficiency, is a better filter medium for COCS than charcoal. The compaction and California bearing ratio (CBR) properties of the COCS also improved with the filter media enhanced EKR. However, the CBR values for the filter media enhanced EKR soils only meet the 20% minimum requirements for Type 2 sub-base course materials specified for light trafficked Nigeria roads. As such, charcoal or active carbon filter media enhanced EKR technology can be adopted for remediating COCS for light trafficked Nigeria road construction in areas not subjected to flooding.

Loggerhead turtle oceanic-neritic habitat shift reveals key foraging areas in the Western Indian Ocean

Loggerhead sea turtles (Caretta caretta) use both oceanic and neritic habitats depending on their life stage, eventually undertaking an ontogenetic shift. Juveniles likely start foraging in a purely opportunistic manner and later seek resources more actively. In the Indian Ocean, it is still unclear where oceanic-stage individuals go, what they do, and importantly where they forage. Yet, such information is crucial to protect this endangered species from anthropogenic threats such as bycatch in fisheries. To address this, 67 individuals (66 late juveniles and one adult) bycaught in the open ocean were equipped with satellite tags and released in the Southwestern Indian Ocean between 2008 and 2021. Most individuals traveled to the Northwestern Indian Ocean where they used neritic habitats of the continental shelf (i.e., largely between 0 and 200-m depth). Using hidden Markov models, we identified three types of movements likely associated with traveling, wandering, and foraging behaviors. We found that the movement characteristics of these behaviors differ depending on turtles’ target destination and habitat (oceanic vs neritic), highlighting different strategies of habitat use among individuals of presumably the same life stage (late juveniles). The turtles that traveled to the Northwestern Indian Ocean encountered warmer waters (mean = 27.6°C, min. = 20.6°C, max. = 33.1°C) than their counterparts remaining in the Southern Hemisphere (mean = 22.5°C, min. = 14.6°C, max. = 29.7°C) but were found foraging at locations with comparable biomass of potential prey (mean = 2.5 g C m-2, min. = 0.5 g C m-2, max. = 10.4 g C m-2) once in the Northern Hemisphere. It remains obscure why these individuals undertook a trans-equatorial migration. Once in neritic habitats, the proportion of time spent traveling was considerably reduced (from 33% to 19%) and allocated to foraging instead. In light of this, it is very likely that the individuals migrated to the Northwestern Indian Ocean to undergo an oceanic-to-neritic ontogenetic shift. Our study sheds light on the behavioral ecology of loggerhead turtles and identifies important foraging areas in the Western Indian Ocean, with the top-three most densely used ones being the Gulf of Oman, the Central Somali Coast, and the Western Arabian Sea.

New occurrence of Poraniidae (Valvatacea, Asteroidea) in Australia with a new genus and species from deep-sea settings

The Poraniidae (Asteroidea, Valvatacea) is recorded for the first time from Australian waters at deep-sea (&gt;200m) depths, including, at present, Australia’s deepest known asteroid occurrence from 3850 m. Three genera are reviewed, each represented by a single species, Poraniomorpha tartarus n. sp., Marginaster paucispinus Fisher 1913, and Marginaster patriciae McKnight 2006, which is reassigned to the new genus, Bathymarginaster. Comparisons with other asteroid groups similar to the Poraniidae in Australian waters is made and a key to genera of the Poraniidae is provided.

Evaluation of the green mussel floating cage related to the enlightenment aspect through the analysis of the Perna viridis spat settlement & population structure

A floating cage is one of the methods of cultivating green mussels that can potentially be used as a medium for maritime education because it is easily accessible to people of various age groups, especially in green mussel cultivation related to mangrove ecotourism. This study aims to analyze the design of floating cages from light and shaded zones based on the spat density and the population structure. The research was conducted in floating cages operated in the Java Sea, Banyuurip Village, Ujungpangkah District at coordinates 06°52’18.84” South Latitude and 112°29’41.19” East Longitude. The spat density was calculated per collector rope per depth (1-4m). When the green mussels were harvested in five-month cultivation from each zone, the population structure was analyzed with Excel 2010 software and measured for the population frequency distribution to investigate the percentage of mussels that reached consumer size. The differences between open and shaded population variables were evaluated by t-test (α=5%). The results of this study show that the density of spat attachment to the collector in the open space was 17.044±724 individuals/m2, and in the shaded area was 16.085±4634 individuals/m2. The density of the spat at a depth of 1m (22,538±4,536 individuals/m2) was significantly different (p<0.05, with three observations) from the density at a depth of 4m (10,830±1,016 individuals/m2) in a light area. However, the spat settlement between each depth was not significantly different in the shaded area. The population structure of green mussels in both areas had seven length classes (class I-VII) with a 7.8 mm interval. The percentage of the class VI population (47.4-55.20 mm) in the light area (31%) was significantly different (p<0.05) from the shaded area (25.79%). It means that the portion of green mussels suitable for harvest (length 40-80 mm) in the light zone is more than in dark zone. We conclude that lighting is an essential aspect of the rate of spat attachment, survival, and growth. The proportion and position of the shaded area in the floating cages must be adjusted so that the growth of the spat is not blocked.

SEAKEEPING EVALUATION OF SHIPS FOR OPERATIONAL PLANNING IN THE GULF OF GUINEA

This paper evaluates the sea-keeping characteristics of a Platform Supply Vessel (PSV) for operational planning in the Gulf of Guinea according to the respective international requirements or standard criteria. The ship’s design and operation characteristics were examined, the characteristics of the specified sea environment in which the ship should perform its mission were assessed, the impact of the specified sea environment on the design and operation of the ship was evaluated and ultimately, the operational criteria that should not be exceeded, so that the ship can perform its mission effectively was determined. Structural Analysis and Design Computer-Aided Design (SACS CAD) Software was employed to model the ship design and it was subjected to the environment in which it is to operate. The Joint North Sea Wave Project (JONSWAP) spectrum was used to model the local wind sea wave with Orca Finite Element Analysis of Flexible Systems (ORCAFLEX). This analysis showed the dynamic movement of the Platform Supply Vessel (PSV) in the various degrees of freedom (heave, surge, sway, yaw, roll, and pitch). Broad-based results showed that the PSV is fit to be operational. This was because of the various tests that were conducted for normal conditions. The various degrees of freedom offset exerted by the PSV were below the tolerance limit of platform supply vessels (10% of water depth of 100m=10m). The results obtained were for the south, the heave offset of 1.6032m and surge offset of 2.1507m. For the southwest, the heave offset of 1.5033m, the surge offset of 1.0712m, and the sway offset of 1.0753m. For the west, the heave offset of 1.068m, and the sway offset of 1.2114m. Local Sea wind wave in the south direction (180°) exerts the most environmental loading on the designed PSV. This was because of the result obtained for the extreme condition (heave offset of 1.9571m and surge offset of 1.4107m. The PSV stability parameters were also obtained as summarized in Appendix C and known to be within the limit of acceptability and validated by comparing the righting lever, GZ, of the designed PSV in Figure 16 with that obtained by marine.info (2021). Both righting levers, GZs were above the 30 degrees requirement of UKMCA (2008) criteria for PSVs. The GZ obtained was 62.8 degrees which should not be exceeded to prevent the PSV from capsizing. The study contributes to the body of knowledge surrounding seakeeping evaluations of PSVs and serves as a foundation for evaluating the design and performance of these vessels in the demanding offshore environment

Seepage Analysis and the Reservoir Water Pollution Potential under Vertical Dam Structure Planning

A prospective resolution to the intricate predicaments of flooding, sanitation, and the availability of unprocessed water for the populace of Jakarta residents is the implementation of the coastal reservoir paradigm. This paradigm entails harnessing the latent capacity of the Cisadane River flow and its subsequent storage within a retention pond, and then subjecting it to reprocessing to serve as a viable source of raw water. The selection of a vertical seawall design was based on the objective of creating an effective barrier between the reservoir and the sea, while also considering several environmental factors. This design was selected with the aim of minimizing the need for extensive soil excavation and rock placement. However, it is important to note that the risks of construction failure associated with seepage under hydraulic structure and dam stability pose significant challenges. Besides preventing saltwater intrusion and maintaining the integrity of the reservoir as a freshwater source, dam must be designed to mitigate potential seepage failure and intrusion issues. To address these concerns, this study employed numerical simulation using the SEEP/W and CTRAN/W software. The simulation was carried out to analyze seepage discharge under a vertical dam and predict potential seawater intrusion into the reservoir. The dam was examined over a ten-year period, with varying embankment widths of 10m, 20m, and 30m. The analysis considered changes in water level (ΔH) and the addition of a cut-off wall at depths of 5m, 10m, and 15m. The obtained results showed that seepage discharge rates amounted to 3,14x10-4 m3 s-1, 2,67x10-4 m3 s-1, and 2,50x10-4 m3 s-1 for embankment widths of 10m, 20m, and 30m, respectively, under a 1m level difference condition. Following this, the safety factor for piping on vertical embankment was determined as 1.10, 1.34, and 1.39 for widths of 10m, 20m, and 30m, respectively. This factor was found to increase to 4.03 when the embankment distance was widened, and a 15m deep cut-off wall was installed. It is important to note that the seawater intrusion model predicted a seawater concentration of 65,12 g m-3 at the bottom for an embankment width of 10m, while no intrusion was observed at widths of 20m and 30m with ΔH=1m. This study aims to assess potential risks of piping due to seepage and seawater contamination at the Cisadane Estuary.&#x0D;

Seasonal Fluctuation of Nutrients and Primary Productivity of the Coastal Waters of Culaman, Malita, Davao Occidental

The study was conducted to determine the nutrient and chlorophyll-a concentration of coastal water at Barangay Culaman, Malita, Davao Occidental between two seasons. One shot sampling was done during the rainy season on November 19, 2017, and November 26, 2017. It was also done during summer season on March 6, 2018, and March 11, 2018. Water samples were collected in the surface (5-10 cm depth) and subsurface (below 1m depth). Nutrients were analyzed in terms of their concentration expressed in mg/L, including ammonia, nitrate, nitrite, and phosphate. Chlorophyll-a was included being the most reliable index of primary productivity in seawater. Nitrate, nitrite, phosphate, and chlorophyll-a showed high concentration during rainy season while ammonia exhibited a high concentration during summer season. Further, nutrients were found in high concentrations from surface water compared to those from subsurface water. There were no significant differences in nutrient and chlorophyll-a concentrations between stations except for nitrate. In terms of its concentration between rainy and summer season, and between surface and subsurface waters, there were no significant differences in ammonia, nitrate, and phosphate. However, significant differences in the concentrations of nitrite and chlorophyll-a between rainy and summer season and between surface and subsurface water samples were observed. The prevailing levels of temperature, salinity, dissolved oxygen, and turbidity observed during sampling were found to be normal.&#x0D;

Pemetaan Morfologi Ambang Galala Poka (APG)

The Galala Poka (APG) sill is in the form of an underwater hill located in the narrow waters of the TAD and TAL transition zones. The morphology of APG is important to map because it influences the dynamics of water masses during the tidal period in the TAL and TAD Transitional areas, and can even explain the phenomena of cohesive sediment transport and deposition as well as tidal mixing phenomena that often occur around APG. This research aims to map the topographical profile of the APG seabed and calculate its spatial dimensions.The GIS-based mapping method is used to create an APG seabed topographic model using data compiled from sounding results, digital Navionic Sonar Chart data and digital shipping channel bathymetry data. The trapezoidal rule model is used to calculate the APG dimensions. APG seabed 2D and 3D spatial models mapped with ArcGIS 10.8 and Surfer 23.The results of the analysis found the APG boundaries at coordinates 128.19316 – 128.19829E and 3.66027 – 3.56659S and UTM coordinates 410399.1390 ​​– 410969.1292 mT and 9594764.3000 – 9595384.3000 mU. The topography of APG is generally convex with a flat peak at the center. There are variations in the slope of the seabed, especially on the outer side of the APG. APG volume with a reference depth of 0m (LWS) 1,304,828.05 m3, surface area 151,954.65 m2. At a reference depth of 8m, the APG volume is 20,071.95 m3, the area is 94,887.23 m2. At a reference depth of 10m, the APG volume is 351,296.95 m3, and the surface area is 73,012.06 m2.

Soil microbial community composition along chronosequence of the introduction of Phragmites australis at Suncheon Bay

Vegetations of coastal wetlands play a vital role in providing numerous ecological services to the coastal ecosystem and are also key factors affecting the biogeochemical processes in the soil. The acreage of Phragmites australis is expanding and gradually replacing the Suaeda japonica at Suncheon Bay, Republic of Korea. However, the changes in soil microbial community composition caused by Phragmites introduction is poorly characterized. In the present study, soil cores were collected to a depth of 1m (divided into 10 segments of 10 cm) from Suaeda-vegetated, the boundary of Suaeda- and Phragmites-vegetated, Phragmites-vegetated marshes (after 5 and 10 years of the introduction). These samples were analyzed for physico-chemical characteristics, enzyme activities, soil microbial community (phospholipid fatty acids profiling) and abundance of functional genes related to the methane cycle (mcrA, pmoA and dsrA). Results showed that introduction the of Phragmites increased the water content, pH and dissolved organic carbon content in the soil. The contents of total PLFA and microbial group biomarkers of PLFA were observed to be higher in the surface soil and decreased with soil depth. Early introduction of Phragmites (10 yr) sediments had the significantly highest concentrations of total as well as other microbial biomarkers PLFAs compared with other salt marshes. The relative abundance of biomarker PLFAs of Gram-negative bacteria was significantly higher in Phragmites compared to other salt marshes. The abundance of mcrA was significantly highest in Phragmites salt marshes (10 yr) and mixed salt marshes while the abundance of mcrA, pmoA and dsrA were lowest in Suaeda marshes. Our results reflect the chronological effects of the introduction of Phragmites on the physicochemical and microbial community composition which contribute to establishing the relationship between the plant introduction and soil biogeochemical processes in coastal salt marshes.

Long-term numerical modeling of nitrate leaching into groundwater under surface drip irrigation of corn.

Proper management of fertigation is necessary to deal with the harmful impacts of fertilizers. This research aimed to investigate the nitrate leaching rate into groundwater in different fertigation management under the climate change impact in drip irrigation of corn. For this purpose, HYDRUS-2D was calibrated by performing field experiments. Plant water requirement and rainfall were projected until 2050 using LARS-WG6 under the RCP85 scenario. Then, nitrate leaching up to groundwater at the depth of 5m was simulated in the growing season of corn and the like until 2050 in three fertigation scenarios, including S1 (three regional fertigation splits with irrigation efficiency of 85%), S2 (weekly fertigation with irrigation efficiency of 85%), and S3 (optimum fertigation with irrigation efficiency of 100%). Finally, the annual nitrate leaching rate to groundwater and leached amount were compared in the studied scenarios. The results demonstrated that nitrate penetrated to the depth of 117 and 105cm at the end of the first year in S1 and S2 scenarios, respectively. In these scenarios, nitrate will reach groundwater in 2031, but nitrate concentrations will not be the same. In the S3 scenario, the nitrate will reach a depth of 180cm by 2050. Total leached nitrate to groundwater up to 2050 will be 1740, 1200, and zero kg/ha in S1, S2, and S3 scenarios, respectively. Based on the approach of this study, the vulnerability of groundwater to nitrate contamination in different agricultural areas can be evaluated, and appropriate strategies with minimum environmental impacts of fertilizer abuse can be selected accordingly.