Video from Essentials of Oceanography: Ocean Dumping Regulations in U.S. Waters. Click here to watch the video
Though the treaty puts strict limits upon dumping and penalizes breaking them, many developing countries continue to struggle with providing the necessary port garbage disposal facilities for ships to adequately follow the conventions. Nonetheless, some studies have shown the treaty has been effective in reducing the total amount of marine debris, at least in some areas. Other areas, especially the Southern Ocean and the Hawaiian Islands have seen little to no improvement since the implementation of the MARPOL Conventions.
Water Pollution in San Francisco Bay Area
Of North American bodies of water sampled so far, the San Francisco Bay Area is the most polluted by microplastics with an approximation of an average number of 700,000 microplastic fragments/km2 with the range of 15,000-2,000,000 fragments/km2. Researchers sampling wastewater treatment facilities detected approximately one microplastic particle for every 12 liters of treated wastewater discharged into the bay. This may not sound like very much, but it still adds up to about 90 million particles discharged daily. The San Francisco Bay Area is a relatively small body of water enclosed by dense urban populations, which does somewhat explain why the water is so polluted by microplastics, but other North American waterways in similar urban environments don't see the degree of microplastic pollution as the Bay Area. It is currently unknown why exactly the Bay Area has such dense microplastic pollution.