Influence of microplastics on microbial anaerobic detoxification of chlorophenols.

Microplastics (MPs) can absorb halogenated organic compounds and transport them into marine anaerobic zones. Microbial reductive dehalogenation is a major process that naturally attenuates organohalide pollutants in anaerobic environments. Here, we aimed to determine the mechanisms through which MPs affect the microbe-mediated marine halogen cycle by incubating 2,4,6-trichlorophenol (TCP) dechlorinating cultures with various types of MPs. We found that TCP was dechlorinated to 4-chlorophenol in biotic control and polypropylene (PP) cultures, but essentially terminated at 2,4-dichlorophenol in polyethylene (PE) and polyethylene terephthalate (PET) cultures after incubation for 20 days. Oxygen-containing functional groups such as peroxide and aldehyde were enriched on PE and PET after incubation and corresponded to elevated levels of intracellular reactive oxygen species (ROS) in the microorganisms. Adding PE or PET to the cultures exerted limited effects on hydrogenase and ATPase activities, but delayed the expression of the gene encoding reductive dehalogenase (RDase). Considering the limited changes in the microbial composition of the enriched cultures, these findings suggested that microbial dechlorination is probably affected by MPs through the ROS-induced inhibition of RDase synthesis and/or activity. Overall, our findings showed that extensive MP pollution is unfavorable to environmental xenobiotic detoxification.

Long-Term In-Situ Monitoring and Analysis of Terrain in Gas Hydrate Trial Harvesting Area.

With the increase in global energy demand, the exploration and development of natural gas hydrate in sea has become a research hotspot in recent years. However, the environmental problems that may be brought about by large-scale harvesting are still concerns. The terrain monitoring of the trial harvesting area can effectively prevent the geological disasters that may be caused by the development of hydrates. Therefore, we have developed a new terrain monitoring device, which can work in the deep sea for a long time. Firstly, the structure of the sensor arrays and bus-type control system of the device are introduced. Secondly, an arc model with an interpolation method is used for reconstruction of the monitored terrain. Thirdly, after the accuracy of the sensing arrays are verified in laboratory, the device was placed in the Shenhu area of the South China Sea for more than 6 months of in-situ monitoring. Finally, we analyzed the data and concluded that the terrain of the monitored area was relatively flat, where the maximum subsidence was 12.3 cm and the maximum uplift was 2.75 cm.

Revealing the Viral Community in the Hadal Sediment of the New Britain Trench.

Marine viruses are widely distributed and influence matter and energy transformation in ecosystems by modulating hosts' metabolism. The hadal trenches represent the deepest marine habitat on Earth, for which the viral communities and related biogeochemical functions are least explored and poorly understood. Here, using the sediment samples (8720 m below sea level) collected from the New Britain Trench (NBT), we investigated the viral community, diversity, and genetic potentials in the hadal sediment habitat for the first time by deep shotgun metagenomic sequencing. We found the NBT sediment viral community was dominated by Siphoviridae, Myoviridae, Podoviridae, Mimiviridae, and Phycodnaviridae, which belong to the dsDNA viruses. However, the large majority of them remained uncharacterized. We found the hadal sediment virome had some common components by comparing the hadal sediment viruses with those of hadal aquatic habitats and those of bathypelagic and terrestrial habitats. It was also distinctive in community structure and had many novel viral clusters not associated with the other habitual virome included in our analyses. Further phylogenetic analysis on its Caudovirales showed novel diversities, including new clades specially evolved in the hadal sediment habitat. Annotation of the NBT sediment viruses indicated the viruses might influence microbial hydrocarbon biodegradation and carbon and sulfur cycling via metabolic augmentation through auxiliary metabolic genes (AMGs). Our study filled in the knowledge gaps on the virome of the hadal sediment habitats and provided insight into the evolution and the potential metabolic functions of the hadal sediment virome.

Experimental Research on Data Synchronous Acquisition Method of Subsidence Monitoring in Submarine Gas Hydrate Mining Area.

The data synchronous acquisition is crucial to the seafloor subsidence monitoring system for gas hydrate mining areas based on microelectromechanical sensors (MEMS). Because the independent and high-precision time reference sources on land cannot be used on the seafloor, especially in the deep sea, a relative time synchronization method based on input/output (I/O) and controller area network (CAN) bus was proposed to realize the internal time synchronization of the system. To demonstrate the feasibility of the proposed method, tests including the deformation test of the MEMS sensor array under high pressure, synchronous accuracy test, and landslide and collapse simulation tests were carried out. The synchronization method was performed once every 24 h, and the time drift was reduced to 0.38 ms from more than 30 ms, demonstrating that method can achieve consistent internal time of the system. The method does not require additional hardware devices and has adjustable accuracy.