The advent of industrial activities in the deep sea will inevitably expose deep-sea organisms to potentially toxic compounds. Although international regulations require environmental risk assessment prior to exploitation activities, toxicity tests remain focused on shallow-water model species. Moreover, current tests overlook potential synergies that may arise from the interaction of chemicals with natural stressors, such as the high pressures prevailing in the deep sea. As pressure affects chemical reactions and the physiology of marine organisms, it will certainly affect the toxicity of pollutants arising from the exploitation of deep-sea resources. We emphasize the need for environmental risk assessments based on information generated from ecotoxicological trials that mimic, as close as possible, the deep-sea environment, with emphasis to a key environmental factor – high hydrostatic pressure.

Reactivation and chemical modification were used to obtain modified activated carbons with different pore structure and surface chemical properties. The samples were characterized by nitrogen absorption–desorption, Fourier transform infrared spectroscopy and the Bothem method. Using mercury chloride as the target pollutant, the Hg2+ adsorption ability of samples was investigated. The results show that the Hg2+ adsorption capacity of samples increased significantly with increases in micropores and acidic functional groups and that the adsorption process was exothermic. Different models and thermodynamic parameters were evaluated to establish the mechanisms. It was concluded that the adsorption occurred through a monolayer mechanism by a two-speed process involving both rapid adsorption and slow adsorption. The adsorption rate was determined by chemical reaction.

Anthropogenic CO₂ emission is identified as the major cause of climate change. The use of fossil fuels has to be accommodated, possibly with a CO₂ capture process. Sequestration of captured CO₂ at high pressure is proposed as a feasible option for future mitigation of climate change, though using fossil fuels. However, this needs significant energy input and carries the potential threat of a possible future catastrophe. Capture of CO₂ with possible recycling is a long-term sustainable option. In this paper, a process involving a chain of reactions using solid sodium to capture both CO₂ and SO₂ from a flue gas is described. A significantly detailed description of both chemical reactions and physical processes is discussed. Recycling of captured CO₂ and SO₂ in the form of solid graphite and elemental sulphur (as the by-products) is the special feature of this process. However, critical selection of intermediate process liquids and equipment in this process needs further study for real-life implementation of this scheme.