Ammonium depletion associated with the COVID-19 pandemic in the Mexican Caribbean

The Mexican Caribbean contributes significantly to Mexico's gross national product. The number of tourists declined from 16.7 million in 2019 to 8.8 million in 2020 due to the COVID-19 pandemic, with a rapid recovery of 13.5 million in 2021. Wastewater discharge is the primary contamination source associated with the tourism sector's demand for goods and services. Water quality could improve due to fewer tourists arriving during the COVID-19 sanitary emergency. This study aimed to quantify ammonium concentrations at eleven locations to evaluate water quality during the sanitary restriction due to the pandemic in the Mexican Caribbean. The ammonium concentrations were 85 % (Nov-2019), 89 % (Feb-2020), and 86 % (Feb-2021) higher than in Nov-2020, where six of the eleven sampled stations were below the detection limit (0.15 μM). Lower ammonium concentrations coincide with the sanitary restriction period and a decrease in affluent tourists.