Based on the observations and subsequent modelling, the vertical distribution of microplastics in the upper part of water column seems to be affected by wind speed. Sub-surface net tows in North Atlantic subtropical gyre have revealed that microplastics are found also from the depth of 20 meters. Microplastics can be distributed even deeper than couple of meters below the surface. In another study conducted in the northeastern Atlantic Ocean, fibres also made up 95.9 % of the microplastic litter sampled from the depth of 3 meters, where the overall concentration of microplastics was on average 2.46 particles per m -3. From the fibres analysed, the identified polymers included polyester (15 %), polyamide (15 %), acrylic (10 %), polyethylene (5 %), polyvinylchloride (5 %) and cellulose (30 %), possibly rayon. Fibres accounted for 95 % of all found particles followed by fragments and films. 93 % of the samples contained microplastics, and their concentration ranged between 0 and 11.5 particles m -3 and averaged 2.68 particles m -3. Similarly, microplastics were also found in the sub-surface waters of the Arctic waters near Svalbard, Norway, in the depth of 6 meters. The polymer types were, however, not identified, so the origin of fibres remain unknown. Majority of particles were fibres which accounted for three quarters of all the found particles. Since the concentrations were higher near the coast compared to the offshore locations, these results indicate that land-based activities may be the major source of microplastics in the sampled area. The mean concentration was 2080 particles m -3, but concentrations varied from 8 to 9180 particles m -3 depending on the location. Knowledge about macro-sized debris in the water column is extremely scarce, but lately few studies have demonstrated the presence of microplastics in sub-surface waters and deeper layers of water column.įor example seawater samples collected at 4.5 m below the surface in the north-east Pacific Ocean were reported to contain microplastics in all 34 sampling stations. ![]() Plastics can, however, be also neutrally buoyant and float in a certain depth in the water column. This is mainly because plastics were long assumed being submerged in the water column only temporarily and were thought to either be floating on the sea surface or sinking towards the bottom. Plastics are rarely sampled from the water column beneath the sea surface. References Litter might submerge below the surface CORNER: Vertical distribution of microplastics in the Baltic Sea
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |