Spatial distribution of microplastics in the Gulf of Panama
Author
Lewandowska, Magdalena
Term
4. Term
Publication year
2024
Submitted on
2024-06-03
Pages
79
Abstract
Microplastic pollution has been insufficiently studied across regions and for very small particles. To help close these gaps, we sampled the Gulf of Panama in August 2023 for microplastics sized 10–300 µm, using both transect (along-track) and stationary sampling. We also carried out a GIS-based watershed analysis to estimate where and how much microplastic enters the gulf from land. In addition, we simulated particle drift based on sea surface currents and compared the simulations with our measurements. Measured concentrations ranged from 18–817 particles per m3 or 1,359.11–85,821.78 ng per m3. A sampling site’s proximity to presumed pollution sources had little effect on the concentrations we found. Instead, concentrations largely depended on how close the site was to the core of the surface current. The highest levels occurred in the western gulf, closest to the current’s center and receiving inputs from Panama City. Most particles were polyester; the second most common polymer was epoxy resin, consistent with heavy marine traffic in the area. However, turbulence and vertical mixing caused by ship traffic did not show up in the measurements: there was no difference between samples taken within the main shipping route and those outside it. Finally, polyethylene (PE) appears to accumulate in the Gulf of Panama in the same way it does in large ocean gyres, the rotating current systems where plastics often collect.
Mikroplastforurening er kun sparsomt undersøgt, både geografisk og for meget små partikler. For at udfylde nogle af disse huller tog vi i august 2023 prøver i Panamagolfen af mikroplast i størrelsesordenen 10–300 µm, både langs strækninger (transekter) og på faste positioner. Vi lavede også en GIS-baseret analyse af afstrømningsoplande for at skønne, hvor og hvor meget mikroplast der tilføres fra land til golfen. Derudover simulerede vi, hvordan partikler driver med havoverfladestrømme, og sammenlignede modellerne med de målte data. De målte koncentrationer lå mellem 18–817 partikler per m3 eller 1,359.11–85,821.78 ng per m3. Nærhed til en tænkt forureningskilde havde kun lille betydning for, hvad vi fandt i prøverne. I stedet afhang koncentrationerne mest af, hvor tæt prøvestedet lå på kernen af overfladestrømmen. De højeste koncentrationer blev målt i den vestlige del af golfen, hvor prøverne lå nær strømcentrum og modtog tilførsel af mikroplast fra Panama City. De fleste fundne partikler var polyester, og den næstmest almindelige polymertype var epoxyharpiks, hvilket peger på intens skibstrafik i området. Den turbulens og lodrette omrøring, som skibstrafik skaber, kunne dog ikke genfindes i vores målinger: Der var ingen forskel mellem prøver taget i hovedsejladsruten og uden for den. Endelig ser polyethylen (PE) ud til at ophobe sig i Panamagolfen på samme måde som i store hav-gyres, dvs. roterende strømområder, hvor plast ofte samler sig.
[This apstract has been rewritten with the help of AI based on the project's original abstract]