A Novel Sensor for Undrained Shear Strength Measurement in Very Soft to Soft Marine Sediments Based on Optical Frequency Domain Reflectometry Technology.

Due to the short supply of conventional fill materials, such as sand, land reclamation using dredged marine deposits has recently been proposed, in which marine deposits with high water content are blow-filled into reclaiming areas. The strength development of the filled marine soils is of great importance during the sedimentation and consolidation to guide the filling process and construction of reclamation. In this study, a novel sensor based on optical frequency domain reflectometry (OFDR) technology with a simple design was developed for undrained shear strength measurement. The novel sensor consists of an optical fiber and a series of polyoxymethylene coins. Owing to the merits of OFDR technology on high resolution, fully distributed sensing, and immunity to electromagnetic interference, the novel sensor can be used to determine undrained shear strength profiles of very soft to soft marine sediments/soils with good accuracy. The sensor was calibrated in remolded marine deposits with different water contents. The good feasibility and performance of the novel sensor for undrained shear strength measurement were well validated in two physical model tests on marine deposits treated by horizontal drains with vacuum preloading.

Conversion of renewable substrates for biosurfactant production by Rhizopus arrhizus UCP 1607 and enhancing the removal of diesel oil from marine soil

BACKGROUND: The use of agro-industrial wastes to produce high value-added biomolecules such as biosurfactants is a promising approach for lowering the total costs of production. This study aimed to produce biosurfactants using Rhizopus arrhizus UCP 1607, with crude glycerol (CG) and corn steep liquor (CSL) as substrates. In addition, the biomolecule was characterized, and its efficiency in removing petroderivatives from marine soil was investigated. RESULTS: A 22 factorial design was applied, and the best condition for producing the biosurfactant was determined in assay 4 (3% CG and 5% CSL). The biosurfactant reduced the surface tension of water from 72 to 28.8 mN/m and produced a yield of 1.74 g/L. The preliminary biochemical characterization showed that the biosurfactant consisted of proteins (38.0%), carbohydrates (35.4%), and lipids (5.5%). The compounds presented an anionic character, nontoxicity, and great stability for all conditions tested. The biomolecule displayed great ability in dispersing hydrophobic substrates in water, thereby resulting in 53.4 cm2 ODA. The best efficiency of the biosurfactant in removing the pollutant diesel oil from marine soil was 79.4%. CONCLUSIONS: This study demonstrated the ability of R. arrhizus UCP1607 to produce a low-cost biosurfactant characterized as a glycoprotein and its potential use in the bioremediation of the hydrophobic diesel oil pollutant in marine soil

Citreibacter salsisoli gen. nov., sp. nov., a bacterium isolated from marine soil.

A Gram-stain-negative, strictly aerobic, yellow-colored, rod-shaped, chemoheterotrophic bacterium, designated SNA426T, was isolated from marine soil in the Republic of Korea. Preliminary analysis based on the 16S rRNA gene sequence revealed that the novel marine isolate was affiliated with the family Flavobacteriaceae of phylum Bacteroidetes and that it shared the highest (96.2%) sequence similarity with Gillisia mitskevichiae KMM 6034T. The strain could be differentiated phenotypically from related members of the family Flavobacteriaceae. The major fatty acids of strain SNA426T were iso-C15:0, C16:1 ω7c and/or C16:1 ω6c and iso-C17:0 3-OH. The DNA G+C content of the strain was 39.6 mol% and the major respiratory quinone was menaquinone 6 (MK-6). Strain SNA426T had phosphatidylethanolamine, phosphatidylcholine, three unidentified aminolipids and nine unidentified lipids as polar lipids. From the distinct phylogenetic position and combination of genotypic and phenotypic characteristics, the strain is considered to represent a novel genus in the family Flavobacteriaceae, for which the name Citreibacter gen. nov. is proposed. The type species is Citreibacter salsisoli sp. nov., with the type strain SNA426T (= KCCM 90269T = CGMCC 1.16129T).