Water and Climate Change - Chapter 9: Plastic pollution in waterways and in the oceans

Intensive use of plastic products and improper management of plastic wastes have resulted in unprecedented plastic pollution in nearly every corner of the world. Plastic particles in the environment may be fragmented into small pieces (<5mm) commonly defined as microplastics (MPs), which can be synthesized to serve as ingredients in certain consumer products. Plastics/MPs are known to prevalently derive from land-based sources to the oceans/seas via riverine runoff. The ubiquity of plastics/MPs in aquatic environments has gained increasing global attention. This chapter compiled and analyzed available data in the literature on the distribution of plastics/MPs in global oceans/seas and rivers and estimated riverine plastics outflows to global oceans. The results showed that global oceans were heavily polluted by MPs, with the Pacific Ocean containing the highest mean concentration. The concentrations of MPs in oceans/seas were highly correlated to those in adjacent rivers. To estimate the riverine plastic outflows to the global oceans, models have been developed, calibrated, and validated using field data. When all modeling results and field measurements were compared against each other, the Human Development Index was shown to be a better predictor in estimating global riverine plastic outflows than mismanaged plastic waste.