Microplastics: A trojan horse for metals
Hereon study shows that microplastics can serve as a transport vehicle
for metals in the environment

Date:
August 9, 2021
Source:
Helmholtz-Zentrum Hereon
Summary:
The fact that microplastics can accumulate organic pollutants
from the environment and transport them has been known for some
time. What is new, however, is that metals can also be transported
in this manner. In addition, the smaller the particles, the greater
the metal accumulation on the plastic.



FULL STORY ========================================================================== Scientists worldwide have already demonstrated the alarming ecological
ubiquity and longevity of plastic particles. The particles measure between
one micrometer and a half centimeter in size. They develop in part when
larger plastic components break apart in the sea or wind up in the rivers
and subsequently in the ocean directly from wastewater stemming from land.

Microplastics are toxic in very high concentrations. In addition,
they can also accumulate, transport and release other pollutants. While
data has already been published on organic pollutants in this context,
there is little known about the interactions between the microplastic
particles floating in the water and dissolved metals. This is why
scientists from the Institute of Coastal Environmental Chemistry at
the Helmholtz-Zentrum Hereon have now systematically studied these
interactions in the laboratory.


========================================================================== Fifty-five different metals investigated The team, which includes first
author Dr. Lars Hildebrandt, studied the accumulation of fifty-five
different metals and semi-metals on polyethylene and polyethylene
terephthalate particles, measuring 63 to 250 micrometers in size.

"In regard to water polluted by plastics, the two types of plastics we
studied play a vital role," says environmental chemist Hildebrandt. "This
is due to their wide range of application and the associated high
production volumes.

Most shopping bags, for example, are made of polyethylene (recycling
code 4, LDPE), and plastic drinking bottles are almost without exception
made of polyethylene terephthalate (recycling code 1, PET)." The smaller
the particle, the stronger the accumulation "In the study, we determined
that the accumulation becomes stronger when the particles become smaller
and that there are significant differences between the various elements
(metals and semi-metals) in terms of the extent of enrichment," says
coauthor Dr. Daniel Pro"frock, department head of Inorganic Environmental Chemistry at Hereon. Some metals, or more precisely their ions, such
as chromium, iron, tin and the rare earths attached themselves almost
entirely to the microplastics. Others, such as cadmium, zinc and cooper,
showed almost no accumulation on the plastic over the entire test
period. In addition, the polyethylene particles showed significantly
greater accumulation than the polyethylene terephthalate particles.

Metals are almost completely released again In the second phase of the
test, the Hereon scientists could show that the particles loaded with
metals or semi-metals almost completely released the respective metal
contents again under chemical conditions, such as those that prevail
in the digestive tract. "Our test set-up in the laboratory was actually simplified and without model organisms. Nonetheless, the results provide important evidence that microplastic particles, when absorbed by the
body, act as a type of trojan horse for metals and that these metals can possibly be introduced into organisms to a greater extent in that way,"
says Lars Heldebrandt, drawing his initial conclusion.

Further studies are now being conducted to determine how other plastics frequently found in the environment behave and what influence the age
of the particles and their weathering state have on the accumulation
and release processes.

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


========================================================================== Journal Reference:
1. L. Hildebrandt, F.L. Nack, T. Zimmermann,
D. Pro"frock. Microplastics as
a Trojan horse for trace metals. Journal of Hazardous Materials
Letters, 2021; 2: 100035 DOI: 10.1016/j.hazl.2021.100035 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210809144107.htm

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