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Due to Mediterranean climatic conditions, traditional pluvial agrosystems are widespread along the southern Mediterranean shore and were previously thought to have minimal impact on surface water resources due to low agricultural input levels. However, current pesticide applications are now considered to contribute significantly to the contamination of surface water resources, which may result in severe impacts on biodiversity and the environment. This study examined the presence and mobility risk of pesticides in the surface waters of the Lebna watershed in northeastern Tunisia, a rainfed Mediterranean agricultural region. Water samples were collected from eight hilly reservoirs and the Lebna dam over three farming seasons (2017-2018, 2019-2020, and 2020-2021) and analyzed for 469 pesticide active ingredients (PAIs). According to the field questionnaire, local farmers used 44 PAIs, including 15 herbicides, 21 fungicides, and 8 insecticides. Seventeen pesticide molecules were detected, with glyphosate (1.73 µg L -1 ) and 2,4-D (0.23 µg L -1 ) being the most prevalent. Despite toxicity indexes, which classify a threat of pesticides as low to moderate, their concentrations may now exceed European standards for drinking water and endanger aquatic life. According to the Pesticide Impact Rating Index (PIRI), PAIs can be organized into three mobility risk categories: medium to high for 2,4-D and glyphosate, low for five PAIs, and very low for 13 undetected PAIs. This work provides the first assessment of pesticide contamination in surface waters of the Cap Bon region, raising concerns about water quality in a low-input agrochemical system and increasing interest in similar contexts., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Two years of monthly sampling and hydrological monitoring were performed at the outlet of a Mediterranean watershed in northern Tunisia to determine the contents of 469 pesticide active ingredients and metabolites in water and evaluate their behavior. Wadi Guenniche is a tributary of the Bizerte coastal lagoon, with a watershed area of 86 km 2 , which exhibits pluvial cereal, legume, and orchid cultivation and irrigated market gardening. Twenty-nine pesticide active ingredients and 2 metabolites were detected in water. Twenty-four pesticide active ingredients were authorized for use in Tunisia. Among them, 14 had never been mentioned in previous farmer surveys. Five herbicides and their metabolites were the most frequently detected: aminomethylphosphonic acid (AMPA) (100%), glyphosate (94%), simazine (94%), 2,4-D (70%), and deisopropylatrazine (DIA) (47%). The detection frequency and concentration range suggested that the phytosanitary pressure and resulting water contamination are close to those on the northern Mediterranean shore. These results, in addition to characterizing the pollution state, emphasized the need for additional studies on the use and fate of pesticides on the southern shore of the Mediterranean Sea, particularly in Tunisia.