Ocean microplastic pollution may be greater than estimated

Date:
January 25, 2022
Source:
Universitat Autonoma de Barcelona
Summary:
The great diversity of scientific techniques and methods used in the
study of marine microplastics pollution limits the current knowledge
of this serious environmental problem threatening our ecosystems.



FULL STORY ==========================================================================
The great diversity of scientific techniques and methods used in the
study of marine microplastics pollution limits the current knowledge
of this serious environmental problem threatening our ecosystems. This
is the main conclusion of a study carried out by the Institute of
Environmental Science and Technology of the Universitat Auto`noma de
Barcelona (ICTA-UAB) that reviews the research carried out to measure
the presence of microplastics in the coastal areas and seawater of the Mediterranean Sea, both in the sea surface water, seawater column and in
marine sediments. The conclusions show that the levels of microplastics
in the Mediterranean are probably higher than estimated, but the methods
used are not capable of recording them.


========================================================================== Microplastic pollution is one of the environmental problems threatening
our ecosystems, with a growing interest for society. Specifically, the Mediterranean Sea is one of the world's greatest plastic accumulation
areas and presents pollution levels similar to the "great marine garbage
patch" of the Pacific Ocean, since the large population that inhabits
the area and the marine dynamics mean that floating plastics are trapped
in the basin, with few possibilities of escaping into the Atlantic Ocean.

The scientific field that studies this problem is relatively new and its methods are constantly evolving, making it difficult to define the most appropriate terms and techniques with which to identify them. "Plastic materials are numerous and very diverse, with different characteristics
that complicate having a standard framework to analyse them all in the
same way.

Moreover, additives such as pigments or retardants add further
complexity," explains Laura Simon, ICTA-UAB researcher and first author
of the study, published in the scientific journal Environmental Pollution.

The study states that the methods used in laboratories for sampling
are very diverse, "and although this has made much progress in this
scientific field, it has also meant that many of the data produced so
far cannot be compared," she adds and acknowledges that this affects
the current knowledge the scientific community has of this problem.

According to the research, of the 3,000 samples collected in the past
decade, 82.8% were taken in coastal areas, so scientists have less
evidence to understand the distribution of microplastics in the open
sea. Also, nets with a mesh size of 200 microns or more were used
to sample surface waters, so therefore smaller particles cannot be
captured. Studies conducted to date estimate that the Mediterranean
Sea contains 84,800 microplastics per km2 in its surface waters, around
300 microplastics per kilogram of marine sediment, and 59 microplastics
per kilogram of beach sand. "The number of microplastics in the natural environment increases as their size decreases, therefore, the levels of microplastics in the Mediterranean are probably higher, but because of
the methods used we are not able to record them," explains Dr. Patrizia
Ziveri, head of the research line at ICTA-UAB.

Most plastics float in the sea. However, the seabed is considered the
final dumping ground where microplastics are expected to accumulate. "We
still have very little knowledge on the mechanisms that export
microplastics from surface waters to the seafloor, for which we need
more studies in the water column," says Dr. Michael Grelaud, researcher
at ICTA-UAB.

Therefore, they stress the importance of defining a common framework
to compare results and combine methods to be able to characterize the
broad spectrum of plastic pollutants in the Mediterranean Sea and their potential impacts. They also call for greater international collaboration between Mediterranean countries, as currently the eastern part of the
basin and North Africa have been sampled to a lesser extent.

========================================================================== Story Source: Materials provided by
Universitat_Autonoma_de_Barcelona. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Laura Simon-Sa'nchez, Michae"l Grelaud, Marco Franci, Patrizia
Ziveri.

Are research methods shaping our understanding of microplastic
pollution? A literature review on the seawater and sediment
bodies of the Mediterranean Sea. Environmental Pollution, 2022;
292: 118275 DOI: 10.1016/j.envpol.2021.118275 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220125093022.htm

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