Yali Gao

The formation of sunken oils is mainly dominated by the interaction between spilled oils and sediments. Due to their patchiness and invisibility, cleaning operations become difficult. As a result, sunken oils may cause long-term and significant damage to marine benthonic organisms. In the present study, a bench experiment was designed and conducted to investigate the quantitative distribution of polycyclic aromatic hydrocarbons (PAHs) in sunken oils in the presence of chemical dispersant and sediment. The oil sinking efficiency (OSE) of 16 priority total PAHs in the sediment phase was analyzed with different dosages of dispersant. The results showed that the synergistic effect of chemical dispersant and sediment promoted the formation of sunken oils, and the content of PAHs partitioned in the sunken oils increased with the increase of dispersant-to-oil ratios (DORs). Furthermore, with the addition of chemical dispersant, due to the solubility and hydrophobicity of individual PAHs, the high molecular weight (HMW) PAHs with 4–6 rings tended to partition to sediment compared with low molecular weight (LMW) PAHs with 2–3 rings. The synergistic effect of chemical dispersant and sediment could enhance the OSE of HMW PAHs in sunken oils, which might subsequently cause certain risks for marine benthonic organisms.

The unsourced oil contamination on the coast of Bohai Sea has recently attracted scholars to study the formation of sunken and suspended oils (SSO) from oil slicks on the sea surface. In this research, batch experiments have been conducted to study the time-scale effect of the different concentrations of suspended sediments on the formation of sunken oils and suspended oils using three oils (Oman crude oil, Merey crude oil, and 380^# fuel oil) and two sediments (sand and silt) at different temperatures. The results showed that the sunken and suspended oils formed quickly within the mixing time and reached a maximum at the equilibrium time, t_e, and that t_e had a wide range of variation with sediment concentration and type. The oil sinking and submerging efficiency could reach up to 6.33%, 43.82% and 44.44% for 380^# fuel oil, Oman crude oil and Merey crude oil, respectively. It is noted that the increase in sediment concentration and environmental temperature could enhance the formation of SSO but that it had a close relationship with the oil type. Overall, hydrophobic sand had a significantly higher oil sedimentation effect than silt.

The single cell gel electrophoresis (SCGE) is a rapid and sensitive procedure for measuring strand breaks in DNA. In the present study, sea urchin (Hemicentrotus pulcherrimus) was chosen as the test organism and SCGE was applied to assess DNA damage of its gonadal cells exposed to petroleum hydrocarbon. The gonadal cells of sea urchin had been seriously damaged above 50 mg/L of Water Accommodated Fractions (WAFs), whileas no damages occurred in the lower concentrations. There were good linear relationships between exposure days and DNA damage rate, percentage of DNA in the comet tail (%TDNA) as well as comet tail length (TL).

Preparative high-speed countercurrent chromatography (HSCCC) was successfully used for isolation and purification of caffeic acid from Eupatorium adenophorum Spreng with a solvent system composed of ethyl acetate-methanol-water at a volume ratio of 10:1:10, v/v. Using a preparative unit of the HSCCC centrifuge, about a 938 mg amount of the crude extract was separated, yielding 63.2 mg of caffeic acid at purity of 96.0%. Then, the antimicrobial and antivirus drug caffeic acid (C₉H₈O₄) was intercalated into layered double hydroxides for the first time by anion exchange under a nitrogen atmosphere. The product caffeic acid–LDH has been characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and Scanning electron micrographs (SEM), indicating that the drug has been successfully intercalated into LDH.