Marine Soil Research Articles

Bearing capacity and the settlement of foundation on biomodified coastal soil

Construction of the foundation on the marine the soil deposit is susceptible to excessive settlement and the construction of foundation is difficult. Although, the most common practice is to construct the raft foundation in these regions even for the low-rise building, excessive settlement can be observed in several building. So, in the present study, laboratory investigations have been done on the marine soil by modifying it with two different type of biopolymer such as Guar gum and Xanthan gum. The geotechnical properties of the soil modified with 1% and 1.5% biopolymer has been evaluated and the obtained properties has been used for settlement analysis. During the settlement analysis, the foundation soil model has been created as layered soil because the top layer has been replaced by biomodified soil. Several combi-nations have been created by varying the thickness of modified soil layer and the type and percentage of modifying agent. The settlement analysis has been performed in the settle 3D software and the biopolymer modification of soil has been found effective in controlling the foundation settlement.

Screening of bacteriocin producing bacteria obtained from marine soil sediments and their antibacterial activity against diabetic foot ulcer pathogens

Screening of bacteriocin producing bacteria obtained from marine soil sediments and their antibacterial activity against diabetic foot ulcer pathogens

Macro- and Microstructural behaviour of Lime-stabilised marine soil treated with Nano-titanium dioxide

Macro- and Microstructural behaviour of Lime-stabilised marine soil treated with Nano-titanium dioxide

Screening local marine habitats suggests a novel strain Bacillus subtilis MZ1 as a potential fatty acid producer

Within this academic research article, a bacterium isolated from a marine soil environment near the Mediterranean Sea is observed to possess the potential for producing various fatty acids, particularly n-caproic and oleic acids, as evidenced by FAME profiling. Furthermore, the introduction of glucose into the growth medium enhances the production of caprylic acid rather than caproic acid. The 16S rDNA sequencing suggested that the MZ1 strain belongs to Bacillus subtilis and is closely related to many halophilic species. FAME profiling reveals that the isolated MZ1 is competent in the total production of fatty acids compared to other marine bacterial candidates. Furthermore, the results indicate that MZ1 is efficient in the production of many other fatty acids. This exploration suggests that the marine bacterium Bacillus subtilisMZ1 can be used for the synthesis of fatty acids, which could be valuable for biodiesel production and other applications.

Impacts of biochar and slag on carbon sequestration potential and sustainability assessment of MgO-stabilized marine soils: insights from MIP analysis

MgO-based binders enhance soil stability and CO2 sequestration. This study examines soft dredged marine soils treated with MgO, integrated with biochar or slag, demonstrating significant improvements in soil properties and environmental benefits.

A review on bioprospecting of actinomycetes isolated from marine soil samples of India concerning their antimicrobial secondary metabolites

A review on bioprospecting of actinomycetes isolated from marine soil samples of India concerning their antimicrobial secondary metabolites

Reliability analysis of offshore monopile foundations considering multidirectional loading and soil spatial variability

Monopiles are the primary type of foundations for offshore wind turbines. Current monopile design methods do not adequately account for the effects of multidirectional loading and soil spatial variability, which may underestimate the failure probability of the foundations. This study aims to investigate the reliability of offshore monopile foundations considering the effects of multidirectional loading and soil spatial variability. A non-intrusive random finite element method combined with Monte Carlo simulation is employed. The behaviors of monopiles in different spatially variable marine soils and loading paths are simulated. Through the reliability analysis, safety factors (FSdesign) are recommended for different scenarios. The results demonstrate that the combined effects of multidirectional loading and soil spatial variability significantly affect the monopile foundation performance and that ignoring these factors will underestimate the failure probability. If the effect of multidirectional loading is more prominent or the marine soil exhibits stronger spatial variability, a larger FSdesign is required to assure an acceptable failure probability.

Effects of random heterogeneity of soil on VH failure envelopes of the torpedo anchor

ABSTRACTTorpedo anchor is one offshore anchoring which has been gaining popularity recently for floating structures. The torpedo anchor was expected to resist the environmental loading transferred from the floating platform. Thus, the understanding of the holding capacity of torpedo anchors under vertical and horizontal combined loading is the key concern of its design. Nonetheless, most of the previous studies are deterministic without considering the common existing random heterogeneity nature of marine soil. In light of this situation, this paper reports a large deformation random finite element study under the framework of the Monte Carlo method. VH failure envelopes of torpedo anchors in heterogeneous soil were obtained by conducting simulations of continuous extraction procedures along different directions. Furthermore, the strain-softening behaviour of the soil was also accounted for considering the server deformation of the soil. The results show that both the size and shape of the VH failure envelope are significantly affected by random heterogeneity of soil. A series of VH failure envelopes of various probabilities of failure was thus given to guide the design. Results in this paper may be constructive for the safety design of the torpedo anchor.

Mechanics, durability, and microstructure analysis of marine soil stabilized by an eco-friendly calcium carbide residue-activated coal gangue geopolymer

Constructing infrastructure on soft soils demands the implementation of ground improvement. This study proposed an eco-friendly method of stabilizing marine soil using a calcium carbide residue (CCR)-activated coal gangue (CG) geopolymer derived from industrial waste. Laboratory experiments were conducted to investigate the mechanical properties, durability performance, and stabilization mechanisms of stabilized marine soils under multiple wetting-dry cycles. The results highlighted the effectiveness of CG-CCR geopolymer by a content of 15% to achieve satisfactory strength gain over the engineering requirements. However, the largest decrease in strength (71.89%) was observed when the initial water content was beyond 1.5 times the liquid limit (LL). The optimum solution was proposed to have a geopolymer content of 15% or an initial water content of 1.25·LL to exhibit the highest resistance to strength decay after 12 cycles. Compared with water intrusion, mass loss had a more significant effect on soil strength deterioration. The formation of noncrystalline or amorphous-phase reaction products effectively filled intergranular pores and reduced the void space between soil particles, improving the mechanical properties. The CG-CCR geopolymer was demonstrated to offer a promising solution for soil improvement in geotechnical engineering and waste reduction in industry as a soil stabilizer.

Disturbance to adjacent marine deposit by offshore DCM construction

During deep cement mixing (DCM) construction, the ground adjacent to the DCM operation zone could be affected due to lateral soil movements and construction disturbances. For offshore DCM construction, multiple mixing shafts arranged in parallel at the DCM barge allow DCM panels to be constructed in a single operation but may disturb the surrounding marine soil. In this study, the degree of disturbance and the potential disturbance zone are characterized using cone penetration tests with porewater measurement (CPTu). The CPTu test results in marine deposits adjacent to offshore DCM panels before and after construction were used to evaluate the impact of DCM construction on CPTu raw measurements, soil type and soil parameters. By interpreting the in-situ soil states, the impacts on deformation and strength characteristics and the impact range were evaluated. A theoretical solution is also developed to examine the lateral displacement and stress increments caused by DCM construction. DCM construction in general caused adverse disturbance to the surrounding marine soils, decreasing the overconsolidation ratio while increasing the permeability. A more substantial decrease in sleeve friction and increase in pore water pressure was observed in coarse-grained soils.

Hydrocarbons in bottom sediments of coastal waters of the Kazantip peninsula (Azov Sea)

The aim of the article is to study the bottom sediments of the coastal zone of Kazantip peninsula in the Sea of Azov of complexes of hydrocarbon pollution. This water area is a site with a high level of recreational load, despite the presence of a nature reserve there, and is also characterized by a rugged coastline, which causes the accumulation of pollution in bottom sediments. The material for the study was samples of the upper layer of bottom sediments, which were taken in the summer of 2021 in the coastal waters of Cape Kazantip (Sea of Azov) with a manual sampler from depths of up to 1.5 m both within the protected area and beyond its borders. Determination of hydrocarbons in bottom sediments was carried out by gas and liquid chromatography in accordance with certified methods. The paper presents new original materials on the distribution of hydrocarbons in bottom sediments in the area of Kazantip peninsula, as well as an assessment of the local level of pollution of marine soils in this area. The ratio of hydrocarbons of different origin in bottom sediments is given. In addition, possible ways and sources of pollution are indicated. As a result of the study, it was shown that the bottom sediments of the coastal zone of Kazantip peninsula are not polluted and the concentrations of the main groups of hydrocarbons are within the range of average values for the Sea of Azov. But, despite this, there are traces of fresh inflows of petroleum hydrocarbons, which can be of both anthropogenic and natural origin.

Experimental investigation on dynamic shear modulus of undisturbed marine soils in the east coast of China

The dynamic shear modulus G is one of the vital parameters for the dynamic properties of marine soils and is crucial for marine geotechnical engineering design. In order to investigate the G characteristics of various marine soils, a series of resonant column tests were performed on undisturbed marine soils with various depths taken from Bohai Bay, Yangtze River estuary, and Jintang Strait, respectively. In addition, the maximum dynamic shear modulus Gmax and strain-compatible G of the tested marine soils were compared with the marine and terrestrial soils from the published literature. A remarkable finding is that, compared with terrestrial soils, the marine soils in different sea area present the stronger nonlinear behavior with lower shear modulus due to the special depositional environment. With the increasing of H, G in each strain range increase, and the dynamic characteristics of the marine soils gradually transition from nonlinear to linear, the Gmax and reference shear strain γ0 value of marine soils in different sea areas increases linearly with the increasing H, but the Gmax and γ0 growth rate varied with the sea environment and soil type. Based on the quantitative prediction equation of the Gmax and G attenuation relationship (G/Gmax ∼ γ) of various marine soils, a new prediction equation can be also established to predict G value in different depth and strain levels of various marine soils. The proposed equation are validated by independent experimental data of marine and terrestrial soils from the literature. In this regard, the proposed procedure provides a significant advantage in the evaluation of dynamic properties of marine soils in practice.

Assessing microbial diversity in soil samples along the Potomac River: implications for environmental health.

In this study, we investigated the microbial diversity and community composition of soil samples collected from various sites along the Potomac River within an urbanized region. The study integrates microbial analysis into an undergraduate chemistry curriculum, bridging theoretical education with practical, real-world applications. Our findings revealed the presence of both typical marine soil bacteria and bacterial taxa indicative of urbanization and waste runoff. Notably, the identified taxa shared among all samples demonstrated a strong presence of Burkholderiaceae, Nitrosomonadaceae, and Pedosphaeraceae, which are associated with agricultural pollution, organochlorine pesticide contamination, and bromochloromethane pollution. We observed significant variations in microbial community diversity across different sampling sites, emphasizing the influence of environmental factors on microbial abundance and diversity. These insights carry significant implications for understanding the consequences of urbanization on soil microbial communities along the Potomac River and can inform strategies for managing and preserving these ecosystems. Further research is warranted to elucidate the effects of soil health and microbial diversity in this region. IMPORTANCE This study integrates microbial analysis into an undergraduate chemistry class, offering students a hands-on approach to environmental research. We examined the soil along the urbanized Potomac River, discovering a mix of common marine microbes and others that are indicators of urban waste and pollution. Our findings provide valuable insights into the environmental impacts of urbanization on soil health and reveal the effectiveness of using modern genetic tools to teach students about real-world issues. This innovative educational approach not only deepens students' understanding of chemistry and ecology but also prepares them to be thoughtful, informed participants in addressing contemporary environmental challenges while shedding light on the state of the soil microbiome near and around the DC metro area.

A new empirical model for the undrained shear strength of undisturbed marine fine-grained soil based on piezocone penetration tests

Simple, precise, and economical evaluation of the undrained shear strength Su of undisturbed marine soil can facilitate the construction of offshore projects. In this study, piezocone penetration tests (CPTu) were conducted at the site of a wind power project, and consolidated undrained triaxial tests were performed on specimens of undisturbed marine fine-grained soil taken from the site. Analysis shows that the Eslami–Fellenius and Chinese soil classification methods based on CPTu data are more applicable for marine soils. The test results indicate that the stress–strain curve exhibits strain softening if the clay content is less than 30 %, otherwise it exhibits either strain hardening or strain stability. Furthermore, the specimens exhibit two deformation failure modes: softening contraction and hardening dilatancy. From the correlation between the consolidated undrained triaxial test data and the CPTu data, Su can be determined simply via an explicit expression involving the measured pore pressure behind the cone (u2), the corrected cone tip resistance (qt), and the soil depth H, and this expression is significantly more precise than the existing empirical formulas. The proposed method offers a sound basis for designing the foundations of marine engineering and infrastructure projects in different sea region.

Optimization of subtilisin production from Bacillus subtilis strain ZK3 and biological and molecular characterization of synthesized subtilisin capped nanoparticles

The increase and dissemination of multi-drug resistant bacteria have presented a major healthcare challenge, making bacterial infections a significant concern. The present research contributes towards the production of bioactive subtilisin from a marine soil isolate Bacillus subtilis strain ZK3. Custard apple seed powder (raw carbon) and mustard oil cake (raw nitrogen) sources showed a pronounced effect on subtilisin production. A 7.67-fold enhancement in the production was evidenced after optimization with central composite design-response surface methodology. Subtilisin capped silver (AgNP) and zinc oxide (ZnONP) nanoparticles were synthesized and characterized by UV–Visible spectroscopy. Subtilisin and its respective nanoparticles revealed significant biological properties such as, antibacterial activity against all tested pathogenic strains with potential against Escherichia coli and Pseudomonas aeruginosa. Prospective antioxidant behavior of subtilisin, AgNP and ZnONP was evidenced through radical scavenging assays with ABTS and DPPH. Subtilisin, AgNP and ZnONP revealed cytotoxic effect against cancerous breast cell lines MCF-7 with IC50of 83.48, 3.62 and 7.57 µg/mL respectively. Characterizations of nanoparticles were carried out by Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray, X-ray diffraction, thermogravimetric analysis and atomic force microscopy analysis to elucidate the structure, surface and thermostability properties. The study proposes the potential therapeutic applications of subtilisin and its nanoparticles, a way forward for further exploration in the field of healthcare.

The inhibit behavior of fluids migration on gas hydrate re-formation in depressurized-decomposed-reservoir

Hydrate re-formation can lead to the blockage of gas recovery during natural gas hydrates production process. However, the hydrate re-formation induced by fluid migration is ignored. In this work, hydrate re-formation behaviors in porous media were investigated via two types of the fluid migration: gas migration and liquid migration. The gas migration was conducted by the following two ways: migration from top to bottom, and migration from bottom to top. The marine soil from South China sea was utilized to reconstruct hydrate samples. The results indicated that the average temperature rise with liquid migration is twice as large as that of the gas migration. What's more, the maximum temperature increment of decomposed-reservoir reaches 9 K. In addition, it was found that there was a duration of 60 min until hydrate re-formation at the end of the liquid migration process. Surprisingly, the fluid migration had a positive influence on inhibiting hydrate re-formation. The findings of this study suggest that the fluid migration could inhibit the hydrate re-formation in depressurized-decomposed-reservoir.

Novel Bioactive Compounds from Streptomyces sp. NLKPB45 Isolated from Marine Soil Sediment

Novel Bioactive Compounds from Streptomyces sp. NLKPB45 Isolated from Marine Soil Sediment

Continuous measurement of gas permeability in non-homogeneous hydrate reservoirs under effective pressure via a novel apparatus

Gas permeability is a key physical parameter to determine the exploitation efficiency of natural gas hydrate (NGH). However, the relevant research mainly focuses on the permeability of homogeneous hydrate reservoirs, there have been no studies of non-homogeneous hydrate reservoirs. Therefore, a novel permeability measurement apparatus was designed in this study, which used two core holders in parallel to achieve the spatio-temporal continuous measurements of gas permeability for non-homogeneous reservoirs. Marine soils obtained from the South China Sea were used to remold the non-homogeneous hydrate reservoirs, including two homogeneous hydrate reservoirs with water saturation of 40% (reservoir A) and 80% (reservoir B), respectively. The constant gas flow of 0.5 ml/s and constant back pressure of 3 MPa was carried out to measure the gas permeability. The experimental results showed that the gas permeability measured in this work had similar regularities with other literature data. When the effective pressure increased from 1 MPa to 6 MPa, the permeability of reservoir A, reservoir B, and non-homogeneous hydrate reservoir decreased from 15.2 mD to 10.9 mD, 10.5 mD to 4.6 mD, and 12.5 mD to 8.5 mD, respectively. In addition, the variation in the non-homogeneous coefficient showed three stages: 1–2 MPa stage, 2–3 MPa stage, and 3–6 MPa stage. What's more, the permeability damage rate of non-homogeneous reservoirs increased by nearly 35% with the increase of effective pressure. These findings obtained by this apparatus will enhance the understanding of gas permeability in the non-homogeneous hydrate reservoirs, and guide further field exploitation of hydrate reservoirs.

A study to determine effect of metal ions for optimization of L-Asparaginase producers for bioprocessing

The present study encompasses isolation of marine bacteria from marine soil samples collected from Chirala, Coastal area of Andhra Pradesh. Work includes isolation, screening, morphological and molecular characterization of selected L- Asparaginase producers. Purified enzyme was used for enzyme kinetic studies. Marine soil sample was collected in sterile bottle and brought to the lab bench and a total of 12 morphologically distinct bacterial colonies were isolated from collected marine soil samples and coded as Chirala Marine Bacteria. All 12 Chirala Marine Bacteria isolates were qualitatively screened for L-Asparaginase production. Out of 12 Chirala marine bacteria isolates, 9 isolates show positive response to L-Asparaginase activity. Effect of inducers i.e. carbon, nitrogen, aminoacids, phosphates and metal ions was studied.

Dye Decolorization of Textile Dyes by Using Aspergillus fumigatus Isolated from Marine Soil

Dye Decolorization of Textile Dyes by Using Aspergillus fumigatus Isolated from Marine Soil