Questions 1-5 are based on the following
This passage is excerpted from Marcus Eriksen’s "Plastic Pollution in the World’s Oceans: More Than 5 Trillion Plastic Pieces Weighing Over 250,000 Tons Aﬂoat at Sea," ©2014.
Plastic pollution is globally distributed across all oceans
due to its properties of buoyancy and durability, and the
absorption of toxicants by plastic while traveling through the
environment has led some researchers to claim that synthetic
5 polymers in the ocean should be regarded as hazardous
waste. Through photo degradation and other weathering
processes, plastics fragment and disperse in the ocean,
converging in the subtropical gyres.* Accumulation of plastic
pollution also occurs in closed bays, gulfs and seas
10 surrounded by densely populated coastlines and watersheds.
Despite oceanographic model predictions of where debris
might converge, estimates of regional and global abundance
and weight of ﬂoating plastics have been limited to
microplastics less than 5 mm. Using extensive published and
15 new data, particularly from the Southern Hemisphere
subtropical gyres and marine areas adjacent to populated
regions corrected for wind-driven vertical mixing, we
populated an oceanographic model of debris distribution to
estimate global distribution and count and weight densities of
20 plastic pollution in all sampled size classes.
Plastics of all sizes were found in all ocean regions,
converging in accumulation zones in the subtropical gyres,
including southern hemisphere gyres where coastal
population density is much lower than in the northern
25 hemisphere. While this shows that plastic pollution has
spread throughout all the world's oceans, the comparison of
size classes and weight relationships suggests that during
fragmentation plastics are lost from the sea surface.
The observations that there is much less microplastic at the
30 sea surface than might be expected suggests that removal
processes are at play. These include UV degradation,
biodegradation, ingestion by organisms, decreased buoyancy
due to fouling organisms, entrainment in settling detritus, and
beaching. Fragmentation rates of already brittle microplastics
35 may be very high, rapidly breaking small microplastics
further down into ever smaller particles, making them
unavailable for our nets (0.33 mm mesh opening). Many
recent studies also demonstrate that many more organisms
ingest small plastic particles than previously thought, either
40 directly or indirectly, i.e. via their prey organisms. Beginning
of reading passage footnotes.
*In oceanography, a “gyre” refers to a large system of rotating ocean currents.