Non-linear relationships between climate and toxic metals in stressed polluted areas

Human activities and climate change are increasingly stressing the environment, causing significant threats to our society. However, interactions between climate conditions and pollution and their impacts on the environment are still understudied. The present study addressed this gap by investigating 40 environmental media, including abiotic (water, soil, litter) and biotic (plants, fungi) matrices, over three years (2019-2021) in a highly polluted area located in Romania. Climate conditions were characterized by a record-breaking heatwave in August 2020 and cool-wet conditions in 2021. Zn and Ni concentrations in water, while Cd, Hg, and Pb concentrations had values above the recommended limits in soil and sediments. In the trees, high concentrations of Pb (854 mg/kg) and Al (653 mg/kg) were found. Trees, shrubs, and herbaceous plants demonstrated low bioavailability for Fe, Li, Al, Ce, Pb, and As, while mushrooms showed high enrichment factors for toxic metals, including Cd, Hg, and As. All biotic matrices show that the bioaccumulation capacity for Hg, Pb, and Cd increased in 2020, and this trend was maintained in 2021. Extreme temperatures and wide diurnal temperature ranges showed a non-linear relationship with chemical elements in the abiotic matrices. In the case of biotic matrices, fitted models revealed minor interactions with precipitation and a strong influence of year, evaluated organ, and species. The limited influence of climatic factors on some biotic components can be attributed to more rapid adaptation in herbaceous plants and fungi compared to trees, as well as species-specific bioavailability. This study offers in-depth insights into how metals respond to climate fluctuations in biotic and abiotic matrices. The results provide a foundation for developing adaptation strategies and measures to mitigate the impacts of interactions between climate stress and metal pollution.