Assessing the Degradation of Conventional and Biodegradable Microplastics in Soil from King George Island, maritime Antarctica

In recent years, microplastic (MP) pollution has become a global concern, even reaching remote and pristine environments like Antarctica. Antarctica is a sensitive environment, critical to global biodiversity conservation and climate regulation, and therefore has attracted interest for scientific research. Despite its remoteness, King George Island, located in the South Shetland Islands, experiences significant ship traffic due to its strategic location. The island hosts ten permanent research stations and the only airport in the region. Increasing human activity, including tourism and research operations, along with atmospheric and oceanic circulation, has contributed to microplastic contamination in both marine ecosystems and terrestrial soils. In sensitive environments such as the ice-free periglacial zones where most human activities in Antarctica are concentrated, soil plays a critical role in terrestrial ecological processes, such as mediating biological and hydrological processes, as well as nutrient and chemical cycling. The presence of MPs in soil can alter its properties, potentially affecting their ability to perform its essential ecosystem functions. Biodegradable plastics have been proposed as a solution to mitigate the environmental impacts of conventional plastics. However, their degradation is highly variable across different environments, with incomplete degradation leading to the formation of MP that still pose a threat to ecosystems.This study investigates the degradation of conventional and biodegradable MP on Antarctic soils through an incubation experiment using Cambisol collected from a marine terrace in the Admiralty Bay, King George Island (0-10 cm). The experiment was conducted at 25% moisture and 4°C, with two treatments and four replicates each, where the soil was spiked with conventional and biodegradable MPs. A control treatment, consisting of non-spiked soil, and empty jars as blanks, were also included. CO2 concentration and δ13C-CO2 isotopic signatures were measured using cavity ring-down spectroscopy, additionally phospholipid fatty acids (PLFA) analyses allowed us to distinguish between microbial groups. The carbon and nitrogen concentration including corresponding isotopes were assessed using EA-IRMS. MP degradation was evaluated through FTIR carbonyl index analysis and δ13C-CO2 mixing model. We will present the preliminary results from this controlled incubation experiment assessing the impact and dynamics of conventional and biodegradable MP on soil from Antarctica.