posted on 2024-02-23, 19:35authored byRobby Rynek, Mine B. Tekman, Christoph Rummel, Melanie Bergmann, Stephan Wagner, Annika Jahnke, Thorsten Reemtsma
The pollution of
the marine environment with plastic debris is
expected to increase, where ocean currents and winds cause their accumulation
in convergence zones like the North Pacific Subtropical Gyre (NPSG).
Surface-floating plastic (>330 μm) was collected in the North
Pacific Ocean between Vancouver (Canada) and Singapore using a neuston
catamaran and identified by Fourier-transform infrared spectroscopy
(FT-IR). Baseline concentrations of 41,600–102,700 items km–2 were found, dominated by polyethylene and polypropylene.
Higher concentrations (factors 4–10) of plastic items occurred
not only in the NPSG (452,800 items km–2) but also
in a second area, the Papaha̅naumokua̅kea Marine National
Monument (PMNM, 285,200 items km–2). This second
maximum was neither reported previously nor predicted by the applied
ocean current model. Visual observations of floating debris (>5
cm;
8–2565 items km–2 and 34–4941 items
km–2 including smaller “white bits”)
yielded similar patterns of baseline pollution (34–3265 items
km–2) and elevated concentrations of plastic debris
in the NPSG (67–4941 items km–2) and the
PMNM (295–3748 items km–2). These findings
suggest that ocean currents are not the only factor provoking plastic
debris accumulation in the ocean. Visual observations may be useful
to increase our knowledge of large-scale (micro)plastic pollution
in the global oceans.