Study of the occurrence of microplastics in soils and underground water of the anaga biosphere reserve (tenerife, canary islands, spain)

The irruption of plastics has supposed an unprecedented development in the recent human history, but their persistence has also led to a continuous and profound deterioration of the environment. As a consequence, they are currently considered as a serious problem worldwide. Even worst, the release of these materials into the environment eventually yields to the formation of microplastics (MPs), defined as plastic particles between 5 mm and 1/0.1 µm in size. Indeed, these anthropogenic particles have been found in all the environmental compartments due to their small size and easy mobilisation, and potentially causing harmful effects. The present study aims to evaluate the occurrence of MPs in soils and underground water of the Anaga Biosphere Reserve (Tenerife, Canary Islands, Spain), a treasured natural area showing a geological, cultural, and biological relevance. A total of 32 soil samples were taken from pristine and agricultural areas, as well as from population centres and viewpoints subjected to a high touristic activity. In each sampling point, soils were acquired following two different methodologies, i.e., by delimiting a 0.5 m2 area via quadrants to collect the first 2 cm of soil, and also by combing four subsamples of the first 5 cm layer taken with stainless-steel cores. Regarding underground water, 22 samples were collected from galleries, wells, and springs placed within the boundaries of the Rural Park. Once at the laboratory, soils samples were mechanically or chemically treated to remove MPs from soil matrixes, and water samples were vacuum-filtered. In all the cases, MPs were finally retained in stainless-steel filters; visualised via stereomicroscopy; classified according to their colour, size, and shape; and analysed via Fourier transform infrared spectroscopy to determine their chemical composition. Acknowledgments: Authors would like to thank Santa Cruz Foundation for financial support (Anaga Project) and Island Water Council for management. Also see: https://micro2024.sciencesconf.org/559712/document