REPORTS

Contents
Page
EXECUTIVE SUMMARY ......................................................................... 11
ACKNOWLEDGEMENTS ........................................................................ 13
1 INTRODUCTION ..................................................................... 15
1.1 Context ......................................................................... 15
1.2 GESAMP WG40 work programme and timeline .......................................... 15
1.3 Structure and scope of the report ..................................................... 16
2 SOURCES OF MICROPLASTICS ...................................................... 17
2.1 Lessons from the first assessment .................................................... 17
2.2 Primary and secondary sources of microplastics ........................................ 17
2.2.1 Overview of microplastic sources ............................................. 17
2.2.2 Fragmentation and degradation .............................................. 18
2.3 Sources by sector ................................................................. 20
2.3.1 Sources in brief ........................................................... 20
2.3.2 Producers and converters ................................................... 20
2.3.3 Land-based sectoral consumers .............................................. 21
2.3.4 Sea-based sectoral consumers ............................................... 22
2.3.5 Individual consumers ....................................................... 25
2.3.6 Waste management ........................................................ 25
2.4 Entry points to the ocean ........................................................... 26
2.4.1 Rivers ................................................................... 26
2.4.2 Coastline ................................................................ 30
2.4.3 Marine ................................................................... 31
2.4.4 Atmosphere .............................................................. 32
2.5 Scale variability ................................................................... 32
2.5.1 Time-scale-dependency .................................................... 32
2.5.2 Regional scale dependency .................................................. 33
2.6 Conclusions, knowledge gaps and priorities ............................................ 34
2.6.1 Conclusions .............................................................. 34
2.6.2 Knowledge gaps .......................................................... 34
2.6.3 Research priorities ......................................................... 34
3 DISTRIBUTION, FATE AND ‘HOT-SPOTS’ .............................................. 36
3.1 Lessons from the first assessment .................................................... 36
3.2 Microplastics in ocean compartments ................................................. 36
3.2.1 Compartments in brief ...................................................... 36
3.2.2 Microplastics on the ocean surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.2.3 Microplastics in the water column ............................................. 37
3.2.4 Microplastics on the seafloor ................................................. 37
3.2.5 Shoreline/Coastal regions ................................................... 39
3.2.6 Biota .................................................................... 39
3.3 Transport within compartments ...................................................... 39
3.3.1 Upper ocean .............................................................. 39
3.3.2 Water column ............................................................. 40
GESAMP REPORTS & STUDIES No. 93 – MICROPLASTICS IN THE OCEAN · 5