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FPSO is the main development model of deepwater oil field in South China Sea, and it has high requirements for the reliability of single-point mooring system. Therefore, the design investigation of inverse catenary of deepwater FPSO mooring suction pile was conducted. Meanwhile, a complete mathematical model for inverse catenary of suction pile was established based on the characteristics and mechanics of seabed soil, and a calculation method for the slack of inverse catenary was proposed. Besides, taking a deepwater FPSO project in the South China Sea as the research object, analysis on mooring under the designed survival condition (1 000-yr-RP) and the designed extreme condition (100-yr-RP) was performed based on the mooring load conditions required by classification societies to obtain the seabed mooring load. As shown by the evaluation results on design of embedded chain inverse catenary and its slack, the tension range of the embedded chain inverse catenary for suction pile of this FPSO mooring is 10 254 kN to14 075 kN, the load angle range is 16.2° to 30.1°, and the horizontal projection distance of the embedded chain is 47.33 m to 80.30 m. Further, the results based on different rules are close to each other for mutual verification. The final results of analysis and design could provide experience for similar FPSO projects.

Antibiotics easily remain in sediments after migrating from the surface to the subsurface due to water-rock interactions, posing a risk of secondary release to groundwater. To investigate the vertical distribution characteristics and environmental impact factors of antibiotics, five 30 m quaternary sediment columns were drilled and stratified near the hospital, and five major classes of antibiotics and sulfonamide metabolites were tested and analyzed. The results showed that:① the antibiotic content in the sediments ranged from 3.05 to 107.03 μg·kg -1 , and all of the target antibiotics were detected except lomefloxacin, of which ofloxacin and oxytetracycline were the most important antibiotics in the study area. ② The antibiotics did not show a strict downward trend in the vertical direction but varied with the lithological stratification. ③ Antibiotics were primarily deposited in the clay layer and varied with the fluctuation of the groundwater level. ④ The results of redundancy analysis between antibiotics and environmental factors suggested that pH and TOC controlled the fate and transformation of antibiotics through influencing the adsorption of antibiotics by sediments. The risk of antibiotic contamination from hospital wastewater seepage into the subsurface environment should be taken seriously.