201. Beaching patterns of plastic debris along the Indian Ocean rim
- Author
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Van Der Mheen, Mirjam, Van Sebille, Erik, Pattiaratchi, Charitha, Sub Physical Oceanography, Marine and Atmospheric Research, Sub Physical Oceanography, and Marine and Atmospheric Research
- Subjects
0106 biological sciences ,010504 meteorology & atmospheric sciences ,Equator ,010501 environmental sciences ,Monsoon ,Oceanography ,01 natural sciences ,03 medical and health sciences ,Ocean gyre ,14. Life underwater ,Southern Hemisphere ,lcsh:Environmental sciences ,0105 earth and related environmental sciences ,030304 developmental biology ,lcsh:GE1-350 ,geography ,0303 health sciences ,geography.geographical_feature_category ,Great Pacific garbage patch ,010604 marine biology & hydrobiology ,Palaeontology ,lcsh:Geography. Anthropology. Recreation ,Debris ,Ocean dynamics ,lcsh:G ,13. Climate action ,Bay ,Geology - Abstract
A large percentage of global ocean plastic waste enters the northern hemisphere Indian Ocean (NIO). Despite this, it is unclear what happens to buoyant plastics in the NIO. Because the subtropics in the NIO is blocked by landmass, there is no subtropical gyre and no associated subtropical garbage patch in this region. We therefore hypothesise that plastics "beach" and end up on coastlines along the Indian Ocean rim. In this paper, we determine the influence of beaching plastics by applying different beaching conditions to Lagrangian particle tracking simulation results. Our results show that a large amount of plastic likely ends up on coastlines in the NIO, while some crosses the equator into the southern hemisphere Indian Ocean (SIO). In the NIO, the transport of plastics is dominated by seasonally reversing monsoonal currents, which transport plastics back and forth between the Arabian Sea and the Bay of Bengal. All buoyant plastic material in this region beaches within a few years in our simulations. Countries bordering the Bay of Bengal are particularly heavily affected by plastics beaching on coastlines. This is a result of both the large sources of plastic waste in the region, as well as ocean dynamics which concentrate plastics in the Bay of Bengal. During the intermonsoon period following the southwest monsoon season (September, October, November), plastics can cross the equator on the eastern side of the NIO basin into the SIO. Plastics that escape from the NIO into the SIO beach on eastern African coastlines and islands in the SIO or enter the subtropical SIO garbage patch.
- Published
- 2020