# Investigating Plastic–Metal Interactions in Aquatic Environments Using Laser Ablation ICP–MS and Chemical Markers

## TL;DR

This study explores how plastics in water interact with metals using a new method to track metal distribution and biofilm effects.

## Contribution

The novel use of LA–ICP–MS to track metal enrichment in biotically aged plastics provides new insights into plastic–metal interactions.

## Key findings

- Copper enrichment on plastic surfaces indicates biofilm presence and metal accumulation.
- LA–ICP–MS reveals distinct metal distribution patterns not captured by conventional acid digestion methods.
- Biotic aging alters plastic surfaces and influences metal interactions, highlighting biofilm's role.

## Abstract

Plastics in aquatic environments interact with metals,
influencing
their fate and transport. Biotic aging of plastics plays a pivotal
role in this process, but the mechanisms are still unclear. Here,
we employed laser ablation–inductively coupled plasma mass
spectrometry (LA–ICP–MS) to track elemental cross-sectional
distribution in biotically aged plastics and assess metal enrichment
within the biofilm. Copper, sorbed from the water environment, was
used as a marker of biofilm presence, while antimony and tin marked
the plastic phase for polyethylene terephthalate (PET) and polylactic
acid (PLA), respectively. Aged samples revealed distinct metal distribution
patterns tracking copper enrichment on the surface, whereas physicochemical
changes happened on the plastic surface after aging, highlighting
the biofilm presence. Copper depletion in water during the aging experiment
confirmed that aged plastics accumulate this metal, showing the key
role of biofilms in governing this process. Conventional analysis
based on acid digestion of plastic fragments only partially captured
this enrichment, underscoring the added value of LA–ICP–MS
to specifically track metals accumulated from the water in comparison
to those present in the polymer matrix. These results highlight the
need to account for biofilm-mediated processes in risk assessments
and establish LA–ICP–MS as a powerful tool for investigating
metal–plastic interactions.