Mercury, particularly in its methylated form, poses a significant environmental and health risk in aquatic ecosystems. While the toxicity and bioaccumulation of mercury are well documented, there remains a critical gap in our understanding of the mechanisms governing mercury methylation and demethylation in aquatic environments. This review systematically examines the complex interplay of chemical, biological, and physical factors that influence mercury speciation and transformation in natural water systems. We provide a comprehensive analysis of methylation and demethylation processes, specifically focusing on the dominant role of methanogenic bacteria. Our study highlights the crucial function of hgcAB genes in facilitating mercury methylation by anaerobic microorganisms, an area that represents a frontier in current research. By synthesizing the existing knowledge and identifying key research priorities, this review offers novel insights into the intricate dynamics of mercury cycling in aquatic ecosystems. Our findings provide a theoretical framework to inform future studies and guide pollution management strategies for mercury and its compounds in aquatic environments.

With the rapid development of the modern shipping field, the damage caused by ship pollution to the global inland waterways and marine ecosystems has attracted extensive attention from the international community. However, there are fewer reviews on the environmental hazards of domestic ship sewage and its treatment, and a systematic summary of the environmental hazards posed by ship domestic sewage and its treatment is lacking. Based on summarizing the various environmental hazards brought about by a ship’s domestic sewage and the corresponding treatment methods, this study elaborates, in detail, on the specific hazards of the main toxic and hazardous substances contained in a ship’s domestic sewage on the environment and organisms, and the treatment methods of the ship’s domestic sewage and their treatment effects, such as membrane bioreactor (MBR). It is also pointed out that MBR has great potential in the direction of ship domestic sewage treatment, and the solution of its membrane pollution and other problems as well as the exploration of the combination of MBR and other treatment methods will become the focus of future research. A theoretical reference is provided for the study of environmental problems caused by domestic sewage from ships and their treatment options.

Exhaust emissions from ships are significant threats to the environment and human health, necessitating effective control measures and treatment technologies. In response to the increasing stringency of emission regulations set by the International Maritime Organization (IMO) and national governments, the shipping industry must adopt advanced techniques to mitigate these emissions. The study focuses on the current status of exhaust pollution prevention and control on the Lijiang River and describes the latest progress in ship emission management. It summarizes the sources and hazards of nitrogen oxides (NO_X), sulfur oxides (SO_X), and particulate matter (PM) emitted from ships. The study introduces and compares several exhaust treatment key technologies for desulfurization, denitrification, and integrated desulfurization and denitrification to emphasize their principles, processes, and characteristics. It also demonstrates the future prospects for controlling exhaust gas pollution on inland ships and advocates for the development of integrated technologies that are efficient, space-saving, and cost-effective. The research aims to provide a valuable reference for inland ship exhaust pollution prevention and control.

Decabromodiphenyl ether (BDE209) has been widely used because of its excellent flame-retardant properties and ability. On the one hand, many studies have shown that the presence of BDE209 can potentially threaten human health and the environment. The production and processing of products containing BDE209 is prohibited except for special applications in China. On the other hand, the study of BDE209 on respiratory cells is not yet fully understood. Consequently, this study aims to investigate the mechanisms of toxic damage and oxidative stress induced by BDE209 exposure in lung epithelial Beas-2B cells. The proliferation of Beas-2B cells under BDE209 exposure was first analyzed by using a real-time label-free cell analyzer (RTCA). Then the cells’ morphological changes were observed using laser confocal microscopy. Subsequently, the effects of BDE209 exposure alone, combined exposure to N-acetylcysteine (NAC) and BDE209, on reactive oxygen species (ROS) levels and antioxidant defense-related factors in Beas-2B cells were analyzed separately. The results show that BDE209 exposure induces the proliferation of Beas-2B cells with a dose-dependent increase in inhibition. Microscopic observation of Beas-2B cells reveals significant damage and death. The levels of ROS are significantly increased (p < 0.01), the contents of superoxide dismutase (SOD) and malondialdehyde (MDA) are increased, the contents of catalase (CAT) are decreased, and the activities of glutathione peroxidase (GPX) are first decreased and then increased. However, under the co-exposure of NAC and BDE209, ROS levels are significantly reduced (p < 0.01), MDA contents decrease, and SOD activities increase. In summary, BDE209 exposure leads to inhibition of Beas-2B cell proliferation, cellular morphology damage, increased ROS levels, and disturbances in antioxidant defense-related factors. The cells showed toxic damage and oxidative stress. In contrast, NAC can suppress ROS levels, enhance SOD activity, and inhibit GPX activity, thereby alleviating BDE209-induced cellular damage.