Comprehensive Study of Emerging Pollutants in El Hierro Island: A Showcase of Good Practices with Zero Pesticide Impact

The present study focuses on emerging pollutants (EPs) in groundwater, an understudied category with unclear regulatory guidelines regarding their impact on water resources. Regions heavily reliant on groundwater, crucial for agriculture, drinking, and other purposes, face heightened risks of EP contamination. The case study focuses on El Hierro (Canary Islands), a UNESCO-designated biosphere reserve largely powered by renewable energies. Employing high-performance liquid chromatography-mass spectrometry, the concentrations of 70 EPs at 19 locations on El Hierro were assessed. The findings revealed an absence of pesticides in groundwater, and diverse levels of ultraviolet (UV) filters, UV stabilizers/blockers, and pharmaceutically active compounds (PhACs), with La Frontera emerging as the most contaminated municipality. Piezometers and wells exhibited the highest EP concentrations among the different installation types. Notably, sampling depth demonstrated a positive correlation with EP concentration, revealing four distinct clusters dividing the island based on EP presence. Further research is essential to understand the factors contributing to the elevated concentrations of certain EPs at different depths. The results underscore the necessity to, not only implement remediation measures post-EP infiltration into soil and aquifers, but also prevent their introduction into the water cycle through homes, animal husbandry, agriculture, industry, and wastewater treatment plants (WWTPs).