Analysis of benzene, toluene, and xylene contaminants in the groundwater of Tripoli, Lebanon

Globally, groundwater is a critical source of freshwater that supports drinking water, agriculture, and industry. Its protection is vital for long-term water safety and public health. In Lebanon, groundwater provides nearly half of the nation’s water supply; however, it faces significant challenges from unregulated extraction, poor infrastructure, and widespread contamination. The city of Tripoli is particularly vulnerable, where defective underground fuel storage tanks, unmanaged waste, and unrestricted well usage have led to alarming levels of toxins such as benzene, toluene, and xylene (BTX). Such conditions pose serious risks to both water sustainability and human health, emphasizing the critical need for regular monitoring and effective regulation. This study aims to investigate the presence of BTX in the groundwater of Tripoli, Lebanon, and to quantify their compound concentrations using gas chromatography–mass spectrometry. A total of 24 water samples were collected on multiple occasions from private wells during the winter, spring, and summer seasons and subsequently analyzed. Results indicated that BTX concentrations in many of the sampled wells, across most seasons, exceeded the maximum contaminant levels established by the United States Environmental Protection Agency for safe drinking water (0.005 ppm for benzene, 1 ppm for toluene, and 10 ppm for xylene), rendering the water unsuitable for drinking. The study revealed seasonal variations in BTX concentrations, with higher levels detected in spring and summer, and lower levels in winter, likely due to seasonal dilution effects from rainfall and infiltration. Among the BTX compounds, xylene exhibited the highest concentrations, followed by toluene, with benzene present at the lowest levels. The detection of BTX in the sampled groundwater clearly indicates pollution. Consequently, remediation measures are necessary to mitigate long-term health risks associated with these pollutants, and continuous monitoring of BTX levels is strongly recommended to effectively assess and manage groundwater pollution.