Occurrence of contaminants of emerging concern and pesticides and relative risk assessment in Tunisian groundwater

Groundwater is an important source for drinking water supply, agricultural irrigation and industrial uses in the Middle East and North Africa region. Due to the growing need for groundwater use, groundwater quality studies on the presence of contaminants of emerging concern (CECs) and pesticides have gained attention. The Wadi El Bey is one of the most polluted areas in Tunisia. However, very limited data on CECs infiltration into aquifers has been described, in comparison to industrialized countries where groundwater contamination has been comprehensively addressed. To gain early insight into potential contamination, groundwater wells in northeast Tunisia, an area with high population density and intensive agricultural activity were sampled during two seasons and were analyzed with two high resolution mass spectrometry approaches: target and suspect screening. The latter was used for screening banned pesticides. A selection of 116 CECs of which 19 are transformation products (TPs) and 20 pesticides previously prioritized by suspect screening were screened in the groundwater samples. The results showed the presence of 69 CECs and 1 TP and 20 pesticides at concentrations per well, ranging between 43 and 7384 ng L-1 and 7.3 and 80 ng L-1, respectively. CECs concentrations in Tunisian groundwater do not differ from those in industrialized countries. WWTPs were considered the main source of pollution, where the main classes detected were analgesics, antihypertensives and artificial sweeteners and especially caffeine, salicylic acid and ibuprofen were found to be ubiquitous. Regarding pesticides, triazines herbicides and carbamates insecticides pose the highest concern due to their ubiquitous presence, high leachability potential for most of them and high toxicity. The environmental risk assessment (ERA) highlighted the high risk that caffeine, ibuprofen, and propoxur may pose to the environment, and consequently, to non-target organisms. This study provides occurrence and ERA analysis of CECs and pesticides in Tunisian groundwater.