Regulations for the control of air-pollutant emissions from ships within pollutant emission control areas (ECAs) have been issued for several years, but the lack of practical technologies and fundamental theory in the implementation process remains a challenge. In this study, we designed a model to calculate the nitrogen-oxide-emission intensity of ships and the sulfur content of ship fuels using theoretical deduction from the law of the conservation of mass. The reliability and availability of the derived results were empirically evaluated using measurement data for NO_x, SO_2, and CO₂ in the exhaust gas of a demonstration ship in practice. By examining the model and the measured or registered fuel-oil-consumption rates of ships, a compliance-determination workflow for NO_x-emission intensity and fuel-sulfur-content monitoring and supervision in on-voyage ships were proposed. The results showed that the ship fuel’s NOx-emission intensity and sulfur content can be evaluated by monitoring the exhaust-gas composition online and used to assist in maritime monitoring and the supervision of pollutant emissions from ships. It is recommended that uncertainties regarding sulfur content should be considered within 15% during monitoring and supervision. The established model and workflow can assist in maritime monitoring. Meanwhile, all related governments and industry-management departments are advised to actively lead the development of monitoring and supervision technology for ship-air-pollutant control in ECAs, as well as strengthening the quality management of ships’ static data.

This paper deeply discusses the microplastic pollution of ship gray water which is getting more and more attention at present. This paper begins with an overview of the potential sources of microplastics and the current management measures. Then, the research progress on the qualitative and quantitative analysis techniques of Marine gray water microplastics, Marine input estimation and type distribution of microplastics in domestic and foreign literature is reviewed in detail. On this basis, the paper puts forward suggestions for future research directions, including establishing the analysis method of gray water composition based on actual ships, strengthening the research on the basic data of microplastics, formulating the inventory of gray water microplastics discharge from ships, and promoting the improvement and development of the control policy of gray water discharge from ships. These suggestions aim to provide scientific basis and strategic guidance for the treatment of ships' grey water microplastics pollution.