Microplastics in the marine environment

In a previous article, it was mentioned a great ecological disaster in the Saronic Gulf because of a tanker sinking. However, the pollution of the aquatic ecosystem is not only related to events that occur at times, but also to the continuous human activity which effects cannot be directly understood. 

More specifically, in this article we will focus on the environmental impacts of mass production of plastic, which exceeds 240 million tons per year (Rilling, 2012). According to the European Plastics Manufacturers Association, world plastics production grows 3-4% each year, of which the rate of 30-50% is recycled and the rest accumulate in the environment and especially in the oceans; the exact percentage has not yet been determined. Due to their high durability can be maintained for a long time and are fragmented very slowly; eventually occur in the environment in the form of microplastics (Valavanidis, 2014).

Figure 1. Microplastics.

Microplastics: microplastics refer to particles that come from plastic objects that have been discarded in the environment and their diameter does not exceed 5mm. To exist in such small plastic particles means that the objects had been discarded in the environment long time before (Lambert, etc., 2017). Particles of this magnitude constitute one of the main pollutants of the marine ecosystem and enter the marine organisms through swallowing and accumulate inside them, because organisms do not have the ability to break them down (Valavanidis, 2014).

Figure 2. Controlled experiments have shown that perch larva actively chooses to eat microplastic particles instead of real and edible food.

Sources of microplastics.

  Microplastics can enter the environment from various sources and we could characterize them as primary and secondary, depending on the source of their occurrence. Primary, include those that enter the environment as already microplastics, which are used in cosmetic products or as industrial materials. 

Secondary, are those from larger plastic objects that have been shattered after being deposited in the environment; this process of plastic degradation may also be enhanced by solar radiation (UV), which has the ability to reduce lifetime of polymer materials, and also plastics (Busbureli, 2011). 

Another rich source of microplastics could be the agricultural sector, as the mushing of plastic objects is applied or even the washing of machines, can produce residual secondary microplastic fibers. Very small particles of plastics could spread to the environment also through the air, for instance in places like landfills or other surface deposits. Finally, organisms that live mainly on the ground, such as earthworms not only could contribute, in part, to the formation of microplastics, as they have the ability to dissever fragile plastic waste which they consume, but also to disperse them in the soil (Rilling, 2012). Of all the above sources with routine procedures, such as the outflow of precipitations on the ground and subsoil, the microplastics will end up accumulating in coastal areas with extension to the aquatic ecosystem.

Figure 3. World map, coasts of continents with the highest concentrations of microplastics. 

 

The impact of microplastics on the aquatic ecosystem.

 

Researches have shown that microplastics exist almost across the aquatic ecosystem, spread in water, sediment and ocean seabed, with the highest concentrations occurring on the coastlines. However, it is a fact that the actual magnitude of the pollution and the extent to which microplastics are dispersed, are still unknown. Many researchers, however, are worried about the possibility that this continued increase in ocean pollution of microplastics will also affect global warming. As it has been proven that, Arctic ocean ice contains large concentrations of microplastics, and it is emphasized that they are two orders of magnitude larger, at least, from those points mentioned above as the most polluted (watch fig.3). This fact proves that microplastics can be transported thousands of miles away from the urban centers and accumulate there, which certainly happens in the polar ice, which is rightly referred in history as the world's "sinks" of human constructions. What it must be determined, is the magnitude of the pollution of the aquatic ecosystem, because of the ice melting, the microplastics are released again, as well as the toxic effects they will have on the aquatic organisms, because many chemical toxic substances are already adsorbed on these particles (Valavanidis, 2014).

In conclusion

   The aquatic ecosystem is continuously "bombarded" by rubbish and mainly by plastic objects. This has caused great concern to local and international organizations, who are aware of the seriousness of the situation and have already begun actions to reduce the problem. Over the past few years, more individuals have been dealing with the issue of the existence of microplastics in the oceans, from national and international authorities, scientists, the media to the simple consumers as well as the plastics industry. Interest in the existence of microplastics is constantly enhanced because the public is aware of this large scale distribution of microplastic waste in the aquatic ecosystem, as well as the results of researches show that microplastics have a negative impact on marine organisms, as they insert into them through the food chain and even cause them death, because marine organisms are not able to break them down and perhaps the particles could carry toxic substances adsorbed on them (Valavanidis, 2014). Consequently, campaigns are being organized to reduce as much as possible, the waste that ends up in the sea, and hence reduce the microplastics in the aquatic ecosystem.

Bibliography

Johanna Kramm, C. V. (2017). Understanding the Risks of Microplastics: A Social-Ecological Risk Perspective. Accessed [9/12/17], from https://link.springer.com/chapter/10.1007%2F978-3-319-61615-5_11#Sec6

Rillig, M. C. (2012). Microplastic in Terrestrial Ecosystems and the Soil? Berlin, Germany. Accessed [ 9/12/2017], from http://pubs.acs.org/doi/pdfplus/10.1021/es302011r

Scott Lambert, M. W. (2017, Ιούλιος 20). Microplastics Are Contaminants of Emerging Concern in Freshwater Environments: An Overview. Accessed [10/12/2017], from https://link.springer.com/chapter/10.1007%2F978-3-319-61615-5_1#Sec6

Αθ. Βαλαβανίδης, Θ. Β. (2014). Μικροπλαστικά στο Θαλάσσιο Περιβάλλον Περιβαλλοντική Απειλή με Επιπτώσεις στους Ωκεανούς και στους Θαλάσσιους Οργανισμούς. Accessed [10/12/17], from http://www.chem.uoa.gr/wp-content/uploads/epistimonika_themata/microplastics_review.pdf

Μπουσμπουρέλη, Π. Κ. (2011). Επίδραση υπεριώδους ακτινοβολίας UV σε πολυμερή υλικά οικοδομικών εφαρμογών. Accessed [15/12/ 2017], from http://dspace.lib.ntua.gr/handle/123456789/4749

Figure 1 & 2 http://awesomeocean.com/top-stories/baby-fish-eating-plastic-instead-actual-edible-food/

Figure 3. http://news.bbc.co.uk/2/hi/science/nature/6218698.stm