Glitter has already established itself as a raw material for clothing, accessories, decoration pieces, cosmetics and even makeup. And, in this month of Carnival, its popularity reaches its peak.
However, so much brightness does not come without consequences: in recent years, the scientific community has treated the material as an emerging pollutant, as these microplastics (particles less than 5 millimeters in size) are not filtered by traditional water treatment systems and end up being released directly. in rivers and oceans, where they interfere with different aspects of aquatic life.
A study conducted at UFSCar (Federal University of São Carlos) with support from Fapesp (São Paulo State Research Support Foundation) detected an additional problem: in addition to plastic, glitter particles also contain metals, such as aluminum.
According to results published in the New Zealand Journal of Botany, the metal present in glitter can alter the passage of light through the water and compromise photosynthesis — and, consequently, growth — of one of the most common species of macrophyte in Brazil, the Dense Egeriapopularly known as elódea.
Macrophytes are aquatic plants visible to the naked eye that serve as shelter and food for various species, provide shade, produce oxygen and can even be used as a biofilter in phytoremediation projects. The elodea, for example, is widely used to decorate aquariums and artificial lakes.
The researchers analyzed the action of glitter through laboratory tests, which involved in vitro incubations with 400 units of the macrophyte submerged in water from the Monjolinho reservoir, located at UFSCar. Common, commercial-type glitter was used in the experiment, with an average surface area of 0.14 square millimeters.
Four combinations were tested: macrophytes in the presence of glitter (concentration of 0.04 grams per liter) with and without light; and macrophytes in the absence of glitter with and without light (control groups). The photosynthetic rates of each group were then analyzed using a method known as “light and dark flask”, developed in 1927 and widely applied in this type of study. The “clear” vials were exposed to photosynthetically active radiation, while the “dark” vials were shielded to block any light and used to calculate respiration rates.
The results of the experiment made clear the size of the problem: photosynthetic rates of dense E. they were 1.54 times greater in the absence of glitter — responsible for reducing the light intensity that fell inside the bottles. The plants’ respiratory processes were also slowed down, although not as significantly.
“These findings support the initial hypothesis that photosynthesis would suffer potential interference from glitter, possibly due to the reflection of light by the surface of the metal present in these microplastics”, says Luana Lume Yoshida, first author of the work, which was part of her initiation project scientific research at the LBMM (Bioassay and Mathematical Modeling Laboratory) of the Department of Hydrobiology at UFSCar. She is currently a master’s student in the Postgraduate Program in Ecology and Natural Resources.
“In this experiment, we specifically observed the physical interference of glitter in a macrophyte species, but there are other better-known references in the scientific literature about water contamination and the consumption of these particles by several other aquatic organisms”, says Marcela Bianchessi da Cunha-Santino , which is part of the LBMM coordination.
“By fitting all these pieces together, we are able to draw a picture of how the ecosystem functions as a whole and what can happen to the entire food chain — and this is the great difference of the ecological approach.”
“With a robust ‘database’, we will be able to think about public policies that guide a more conscious consumption of this type of material. But, for now, it is important to convey to society that changes in photosynthesis rates, although they may seem far from our reality, are interconnected with other changes that affect us more directly, such as the decrease in primary production in trophic chains in aquatic environments [organismos na base da cadeia alimentar]”, says Irineu Bianchini Jr., also coordinator of LBMM. “If there are already more sustainable alternatives for accessories, why not make the change now?”