The transboundary nature of these issues are: discharge of untreated/partially treated sewage being a common problem. Sewage and organic discharges from the Ganges-Brahmaputra-Meghna River are likely to be transboundary. Plastics and derelict fishing gear can be transported long distances across national boundaries. High nutrient discharges from rivers could intensify largescale hypoxia. Atmospheric transport of nutrients is inherently transboundary. Differences between countries with regard to regulation and enforcement of shipping discharges may drive discharges across boundaries. Tar balls are transported long distances. POPs/PTSs and mercury, including organo-mercury, undergo long-range transport. Sedimentation and most heavy metal contamination tend to be localized and lack a strong transboundary dimension.