Ecotoxicological Risk Assessment and Monitoring of Pesticide Residues in Soil, Surface Water, and Groundwater in Northwestern Tunisia

Abstract

Pesticides play a significant role in agriculture, but their leaching into soil and water poses serious environmental risks. This study examines pesticide contamination in surface and groundwater in northern Tunisia, specifically in Kef governorate, involving a survey of 140 farmers to gather data on agricultural practices and pesticide use. Twenty-four pesticides were monitored and utilized within the Pesticide Environmental Risk Indicator (PERI) model to evaluate environmental risk scores for each substance. Soil and water samples were analyzed using a multi-residue method and liquid chromatography–tandem mass spectrometry. Results showed that 50% of the pesticides assessed had an Environmental Risk Score of 5 or higher. Contamination was identified in water and soil, with 18 and 15 pesticide residues, respectively. Notable concentrations included 7.8 µg/L of linuron and flupyradifurone in water and 1718.4 µg/kg of linuron in soil. Commonly detected substances included the insecticide acetamiprid and fungicides like cyflufenamid and penconazole in water, while soil contamination was linked to fungicides metalaxyl and metalaxyl-m, as well as herbicides linuron and s-metolachlor. Factors such as proximity to treated water points and poor packaging management were discussed as risks. The findings emphasize the need for better monitoring and sustainable agricultural practices to mitigate contamination.

1. Introduction

In Tunisia, agriculture plays a key role in driving rural development and ensuring food security [1,2]. Tunisia has around 10.5 million hectares of agricultural land (65% of the total surface area), which extends across the country [3]. The northwest of Tunisia, including the governorate of Kef, is characterized by a highly capital-intensive agricultural economy in the plains, making this region a food source for the population and a competitive area for exports.

The Kef governorate features vast, fertile land and abundant water resources, including 71 hill lakes, 24 hill dams, 4482 surface wells, and 220 deep wells [4]. The economy of this governorate relies on the agricultural sector, which employs 38% of the regional workforce and provides a stable income for 70% of the population. The Utilized Agricultural Area (UAA), accounting for 70.4% of the governorate’s total surface area [5], is primarily dedicated to the production of cereal (197,560 tonnes per year), followed by vegetables (191,850 tonnes per year), fruit trees (108,645 tonnes per year), and olives (43,800 tonnes per year) [4].

The development of these crops faces challenges from a large number of pests (including insects, diseases, and weeds) that harm the crops and consequently reduce their yields in both quantity and quality. To combat these bio-aggressive agents and mitigate their impact to an economically tolerable threshold, several agronomic strategies have been adopted by producers. Nevertheless, chemical control remains the most commonly used method in Tunisia, as it is elsewhere in the world. Today, more than 4 million tonnes of pesticides are used worldwide each year [6], and this figure is continuously increasing. Developing countries account for 25% of global pesticide consumption, and Tunisia imports nearly 5000 tonnes of pesticides annually, granting 700 import authorizations [7]. The use of synthetic pesticides remains the preferred choice for farmers to ensure good yields and achieve the required standards and economically profitable production levels.

While the use of plant protection products is necessary for producers to attain their objectives regarding production and market quality, it should be noted that pesticides can have harmful effects on human health [8,9]. Many studies have reported a linear relationship between the excessive or inappropriate use of pesticides and the contamination of various environmental compartments [10,11,12]. Contamination of soil or aquatic ecosystems occurs through direct spraying, aerial spraying, agricultural runoff, soil erosion, and other means [13,14]. Therefore, the unregulated and uneducated use of agricultural inputs, particularly pesticides and mineral fertilizers, is considered one of the primary causes of surface and groundwater contamination [15].

Generally, plant protection products have harmful effects on target organisms; however, they can also have undesirable impacts on non-target organisms, including birds [16,17], beneficial insects [18], bees [19], earthworms [9,20], and others, thus reducing biodiversity and disrupting ecological balance. This is explained by the fact that less than 1% of pesticides sprayed in fields reach their intended targets; the rest are dispersed in nature, leading to pollution of soil, air, and water [9].

In Tunisia, almost 50% of pesticides are not currently used rationally [21]. Poor phytosanitary practices and non-compliance with approved doses have recently been highlighted in studies conducted in Tunisia [22,23,24]. The consequences are pollution of various environmental compartments and negative effects on human health.

Despite serious environmental concerns, limited studies have been conducted to assess the environmental risks of pesticide contamination in Tunisia, particularly regarding both groundwater and surface water contamination. Additionally, there is a lack of integrated assessments that combine environmental residue analysis with local agricultural practices. Therefore, this study aims to (i) assess pesticide use patterns and environmental awareness among farmers in the Kef region; (ii) characterize the environmental risk of 24 pesticides using the PERI model; and (iii) monitor pesticide residues in surface water, groundwater, and soil through advanced LC-MS/MS analysis. The results will contribute to a better understanding of the potential environmental impacts of current phytosanitary practices and support more sustainable pesticide management strategies in Tunisian agriculture.

2. Material and Methods

2.1. Study Area

The Kef governorate is located in the northwest of Tunisia. This governorate contains 11 delegations covering 87 sectors [25]. The region’s mountains vary in altitude from 700 to 1200 m, while the plains range between 450 and 600 m above sea level [26]. The study area has various potentialities, notably hydro-agricultural. Developments such as dams, lakes, hill reservoirs, and boreholes have allowed for the expansion of irrigated agriculture in the Kef region for several decades. The governorate had nearly 42,497 hectares in 2018, which is 1/10 of the total irrigated area in Tunisia and 1/3 of that of the Mejerda watershed [26].

2.2. Environmental Exposure Scenarios

To gain a deeper understanding of the phytosanitary practices employed by farmers and to design the exposure scenario for different environmental compartments (especially water and soil), a structured survey was conducted from February to May 2023. It involved interviews with 140 farmers chosen randomly from professionals established in the governorate of Kef, more precisely in the delegations of West Kef, East Kef, Sers, Dahmani, Nebeur, Tajerouine, Touiref, Klaaa Khesbaa, and Kalaa Snen (Figure 1). The sample size was determined based on regional agricultural population data and practical constraints related to accessibility and field logistics.

Farmers were contacted with the assistance of the heads of the extension territorial cells, who facilitated access to local agricultural communities. Data collection was conducted through face-to-face interviews. Prior to each interview, participants were informed about the objectives of the study and provided their verbal informed consent in accordance with ethical research guidelines.

A tailor-made questionnaire was specifically developed for this study by the research team, taking into account local farming practices, environmental concerns, and previous field knowledge. The survey covered several thematic areas, including pesticide use frequency and types, storage conditions, perception of environmental risks (e.g., presence of nearby water sources or beehives), and waste management practices related to phytosanitary products. The questions were of three types: open, semi-open, and closed. They were easy to understand and were answered unambiguously by participants. The local Arabic language was used for communication during the survey.

The interviews with the respondents were supplemented by direct observations, including the types of pesticides used, the storage space, phytosanitary treatments, and risky attitudes.

2.3. Environmental Risk Assessment Methodology

Twenty-four pesticides (herbicides (8), insecticides (7), and fungicides (9)) were chosen for this study. These active substances belong to various chemical families and include some of the most widely used pesticides in cereal growing, legumes, and market gardening in the study area.

2.3.1. Environmental Risk Perception of Studied Pesticide Residues

The PERI (Pesticide Environmental Risk Indicator) model was applied to the 24 studied pesticides to analyze the possible fate of these pesticide residues in the environment and to characterize the consequences and risks for the different compartments of the environment and non-target organisms. PERI is a tool developed as part of the certification process of the International Organization for Standardization (ISO) 14001 [28]. This model is designed to assess the potential impact of pesticides on both terrestrial and aquatic ecosystems. It incorporates data on the physicochemical properties of active substances, the toxicity of pesticides, and their potential exposure to non-target organisms, as well as their behavior, persistence, and bioaccumulation in the environment. Groundwater, surface water, and air compartments are integrated into an equation to calculate an environmental risk score (ERS) [28,29].

The comprehensive details regarding the PERI model were sourced from the American Farmland Trust Center for Agriculture in the Environment [28,29]. The environmental risk score (ERS) for each compound was determined based on various parameters and variables using the following equation:

$$ERS=\left(GUS\ast Kh\right)+{\displaystyle \frac{B+W+D+A+S}{5}}\ast {\displaystyle \frac{Kow}{10}}$$

where GUS represents the groundwater ubiquity score, Kh is Henry’s constant, and Kow denotes the partition coefficient. The parameters B, W, and D correspond to the lethal concentration (LC50) values for bees, earthworms, and Daphnia, respectively. A refers to the effective concentration (EC50) for algae, while S indicates the soil microbe scores. This model employs a ranking system that evaluates pesticide characteristics and toxicity levels on a scale from 1 to 5. All the parameters required for calculating the environmental risk score were obtained from the Pesticide Properties Database (PPDB).

When toxicity data for one or more endpoints were unavailable from reliable sources, the corresponding parameters were excluded from the PERI score calculation. Due to insufficient and inconsistent toxicity data specifically for soil microorganisms (S) across the studied substances, this parameter was entirely omitted from the Environmental Risk Score (ERS) calculation. As a result, the toxicity sum in the formula was divided by 4 instead of 5 to reflect the exclusion of the soil microorganism endpoint. For any other missing toxicity data, the respective parameters were also excluded, and the denominator was adjusted accordingly to ensure proportional weighting of the available endpoints.

In this study, the Environmental Risk Score (ERS), derived from the Pesticide Environmental Risk Indicator (PERI) model, was used as a screening-level tool to evaluate and compare the relative environmental risk of the 24 studied active substances. The ERS index is based on the intrinsic properties of pesticides (e.g., toxicity, persistence, mobility), compiled from the literature and toxicological databases. While the model does not account for local application rates or environmental conditions, it provides a preliminary indication of the theoretical environmental hazard posed by each substance.

2.3.2. Monitoring of Pesticides in Soil and Water Samples

Water Sampling

The selection of sampling sites was based on a combination of criteria, including site accessibility, proximity to pesticide-treated agricultural fields, and prior information provided by agricultural extension services and farmers. The study area is characterized by relatively homogeneous agricultural practices regarding crop types, pesticide usage, and irrigation methods. The five rivers sampled represent the main watercourses in the Kef governorate and traverse the majority of its delegations, thus ensuring broad geographic coverage and environmental representativeness.

The collection of fifteen water samples (ten from wells and five from rivers) was performed from different sites over three days in April 2023. Well samples were collected from ten farms located in the governorate of Kef, more precisely in the delegations of Dahmani, Sers, and Tajerouine. Additionally, river samples were collected from the five most popular rivers in the Kef governorate (Oued Sarrath, Oued Tessa, Oued Errmal, Oued el k’hol Saddin, and Oued Mallegue), which cross different delegations of the governorate. Dug wells are located inside or adjacent (distance < 10 m) to cultivated fields and are generally used for irrigation, watering, washing, and other purposes. Samples are collected manually or pumped, depending on the type of well. Water samples (2 L each) were collected in plastic bottles and well homogenized. Three subsamples of 200 mL each were placed in shaded bottles. These bottles were correctly labeled and transported in cool boxes with ice packs. After transportation to the laboratory, samples were stored at −20 °C.

Soil Sampling

Fifteen soil samples were collected simultaneously with water samples from the surface layer (0–15 cm) in the cultivated areas around the wells (distance < 10 m). The soil surface was cleaned to ensure the samples were free from stones, roots, and remnants of previous crops. A stainless-steel scoop was used to collect the samples, which were then placed in labeled plastic bags and transported to the laboratory in coolers. Each sample consisted of at least five soil subsamples taken from different locations within the field. The samples were thoroughly mixed, and a 200 g subsample was stored at −20 °C until extraction.

2.3.3. Extraction and Analysis of Pesticide Residues in Water and Soil Samples

Extraction and analysis of pesticide residues in the samples (fifteen water samples and fifteen soil samples) were carried out in the laboratory of the Department of Sustainable Food Processes (DiSTAS) at Università Cattolica del Sacro Cuore, Piacenza, Italy. All the analyses were performed in triplicate.

A.

Reagents and standards

Methanol and acetonitrile (HPLC grade) were obtained from Carlo Erba Reagents S.R.L. (Milan, Italy), while formic acid was purchased from Sigma-Aldrich S.R.L. (Milan, Italy). SPE Bond Elut PPL cartridges were purchased from Agilent Technologies (Milan, Italy), and Supel QuE Acetate (Ac) tubes were acquired from Supelco (Bellefonte, PA, USA). Pesticide standards were supplied by VWR International S.R.L. (Milan, Italy). Individual stock solutions (100 mg L⁻¹) of each analyte were prepared in methanol, followed by the preparation of mixed standard solutions at various concentrations (5, 2.5, 1, 0.5, 0.1, 0.05, 0.025, 0.010, 0.001 mg L⁻¹) in methanol.

B.

Pesticide residues in water samples

A modified method developed by Zambito et al. [30], based on solid phase extraction (SPE) and their analysis through HPLC-MS/MS, was followed. As the multiresidue method proposed by Zambito et al. [30] considered higher starting volumes of water and a lower number of pesticides, additional recovery tests were performed. Briefly, the extraction procedure was conducted using Bond Elut PPL (styrene–divinylbenzene) cartridges. Initially, the cartridges underwent conditioning with 5 mL of methanol and 5 mL of Milli-Q ultrapure water, and subsequently, 200 mL of water was passed through the cartridges under vacuum. The cartridges were then dried for 1 h under vacuum. Finally, the active ingredients were eluted with 5 mL of methanol, evaporated under a flow of nitrogen, recovered with 0.2 mL of methanol, and transferred into amber glass vials for LC-MS/MS analysis.

C.

Pesticide residues in soil samples

Dispersive SPE (dSPE), also referred to as the QuEChERS method, was used for PPP extraction from soil. For this, 15 mL of 1% acetic acid in acetonitrile and the contents of the Supel QuE Acetate (Ac) Tube were added to 10 g of homogenized soil samples in a 50 mL PTFE centrifuge tube. The sample was shaken using a vortex for 1 min and centrifuged for 10 min at 4500 rotations per minute (rpm) at 21 °C. Following centrifugation, 8 mL of the acetonitrile layer was transferred to a clean-up tube. The clean-up tubes were then centrifuged again for 10 min at 4500 rpm. The supernatant was transferred to LC-MS vials and analyzed through LC-MS/MS.

D.

LC-MS/MS

After extraction, the samples were analyzed using LC-MS/MS. The system included a Vanquish pump and autosampler, along with a TSQ Fortis triple–quadrupole mass spectrometer (Thermo Fisher Scientific, San Jose, CA, USA). Separation was carried out on an EC-C18 column (2.1 × 50 mm, 5 µm, Agilent Technologies, Milan, Italy). The injection volume was 10 µL, the analysis time was set to 30 min, and the flow rate was 0.2 mL/min. The mobile phases were ultra-pure water containing 0.2% formic acid (phase A) and 0.2% formic acid in acetonitrile (phase B). The gradient for solvent B was programmed as follows: from 30% to 90% between 0–23 min and from 90% to 45% between 23–30 min. For the identification and quantification of each compound, precursor and product ions were referenced from the literature [30,31,32,33,34,35,36]. The collision energy was kept below 35 V, and retention times were within 20 min (Table S1 in the Supplementary Material).

E.

Quality control

The methods for extracting and quantifying both water and soil samples were validated by assessing linearity, matrix effect, limit of detection (LOD), limit of quantification (LOQ), accuracy (in terms of recovery), and precision (in terms of repeatability)

Linearity was determined by evaluating the coefficient of determination (R²) of the calibration curves at concentration levels ranging from 1 to 2500 µg L⁻¹. The matrix effect was calculated by comparing the slopes of curves prepared in solvent with those of blank extracts. Precision was assessed through repeatability and intermediate precision by calculating the relative standard deviation (RSD) of the recovery percentage.

The LOD and LOQ were calculated using the signal-to-noise ratio method. The LOD was defined as the lowest concentration at which the analytical signal could be reliably distinguished, with a signal-to-noise ratio of 3:1. The LOQ was set as the lowest spiked concentration that gave a signal-to-noise ratio of 10:1. For extraction recovery determination, 200 mL of tap water and 10 g of soil were spiked with a pesticide mixture containing twenty-four compounds, achieving a targeted concentration of 50 µg L⁻¹ in water and between 7 µg kg⁻¹ and 500 µg kg⁻¹ in soil. The complete description of the analytical method characteristics, including LC-MS/MS conditions, and the results of the recovery tests for soil and water are presented in the Supplementary Material (Table S1).

3. Results and Discussion

3.1. Environmental Exposure Scenarios and Risks to the Environmental Compartments

3.1.1. Water Resources and Contamination Risks

The obtained results reveal that the majority of farmers (81%) have at least one water point near or within their farm (one (44%), two (30%), three (5%), or more (2%)). The main water points observed among farmers are wells (50%), boreholes (38%), valves (21%), and river waters (12%). Additionally, the uses of these water points are primarily for irrigating crops (78%), watering animals (65%), and for other domestic uses, including drinking (25%) and washing clothes (14%).

The distributions of water points (source: Majel, river, valve, borehole, and well) and their distances from the farm are presented in

Table 1. Distribution of water points used by farmers, categorized by source type and distance from the treated fields.

Water Source Categories	Number of Water Points	Distance (m)
		0–50	51–500	501–1000	>1000
Source	2	1 (50%)	0 (0%)	0 (0%)	1 (50%)
Majel	6	6 (100%)	0 (0%)	0 (0%)	0 (0%)
River	18	8 (44%)	5 (28%)	1 (6%)	4 (22%)
Valve	29	29 (100%)	0 (0%)	0 (0%)	0 (0%)
Borehole	55	50 (91%)	3 (5%)	0 (0%)	2 (4%)
Well	103	94 (91%)	6 (6%)	2 (2%)	1 (1%)

. Survey observations show that the most common types of water points are wells and boreholes. Table 1 presents the proportions (in %) of water points and their distances from the fields. The risk of water contamination can be proportionally aggravated by proximity to the field where the phytosanitary treatments will be carried out. The observations made during the survey reveal that the majority of water points are located inside the fields, with percentages varying between 44% and 100%, which can create the risk of pollution of the water resources used for several purposes [37]. The major risk linked to the proximity of water points to cultivated fields is the potential for environmental contamination. Indeed, large quantities of pesticides are transported by stormwater runoff [14].

3.1.2. Domestic Animals and the Poisoning Risk

The majority of surveyed farmers (79%) practice livestock farming, primarily sheep (86%), poultry (60%), and cattle (45%). This highlights the importance of these livestock species in the region’s agricultural landscape. Pesticides are considered the leading cause of suspected poisoning in domestic animals [38]. According to the testimony of a farmer met in the Dahmani delegation, incidents of death among a few individuals within sheep flocks have been reported following the ingestion of water contaminated by pesticide residues. Additionally, another farmer in Tajerouine witnessed a similar scenario after a sheep ingested freshly treated grass. The present results align with a recent study conducted in Tunisia, which reported cases of poisoning of domestic animals by pesticides [39].

3.1.3. Non-Target Organisms and the Toxicity Risk

The obtained results revealed the presence of beehives in 28% of the visited farms, of which more than half of the interviewed farmers have hives located within the farm at a distance of between 0 and 50 m. This increases the risk of exposure of these non-target organisms to different types of active substances [40]. These environmental compartments are at risk due to the poor agricultural practices reported by the respondents.

Honeybees play a crucial role as primary pollinators for economically valuable crops. However, they are among the most exposed non-target organisms to pesticides and their negative effects [41]. They utilize crops not only as food sources but also as nesting sites [40]. These non-target organisms can be affected by plant protection products [19,42]. Furthermore, the results indicate that 41% of farmers noticed a disappearance of insects and animals during the treatment period, including ladybugs (44%), butterflies (19%), birds (28%), slugs, and earthworms (1%). Bees and butterflies play a crucial role as pollinators for many crops [41,42]. In addition, beneficial insects, notably ladybugs, facilitate the biological control of certain insect pests [43]. The decrease in their population can have a direct impact on agricultural production. Moreover, synthetic pesticides can cause undesirable impacts on birds [16,17]. During the investigation and field observations carried out, the death of a bird was noted, following the ingestion of water contaminated by pesticide residues.

3.1.4. Phytosanitary Practices and Attitudes Toward Environmental Risks

Regarding the cleaning of sprayer equipment, 96% of surveyed farmers wash their equipment after the application of pesticides on the farm (50%), in water points (27%), or at home (19%). However, a minority do not clean their equipment (4%). It should be noted that if the cleaning of sprayer equipment is not carried out properly, it increases the chances of water and soil contamination.

Concerning pesticide mixture, the majority of interviewed farmers finish all the pesticide preparation in the sprayer (65%); others reuse the rest to carry out another treatment (19%), dump it in nature (14%), or dispose of it in water points (1%), which can lead to an increased risk for the different compartments of the environment. This practice poses a danger to the ecosystem and can have harmful consequences for the surrounding fauna, flora, and ecosystems. Furthermore, it is concerning that 1% of farmers dump the pesticide mixture directly into waterways, which is extremely harmful to water and can cause widespread contamination. Different studies have reported and documented similar practices [44,45,46,47,48].

Regarding empty pesticide packaging, most of it is burned (47%) or thrown into nature (35%). Four farmers reported that they threw the packages into the rivers. Other farmers reuse them for other purposes (using empty packaging such as for century-old diesel, water, etc.) (9%), bury them (5%), or dispose of the packaging with household waste (4%). This empty packaging increases the risk of contamination of soil and water, thus creating a major concern for public health. This situation can lead to risks of poisoning or even death of non-target organisms [29,48,49,50,51,52,53].

3.2. Potential Hazard Characterization of Studied Pesticide Residues

Twenty-four pesticides (herbicides (eight), insecticides (seven), and fungicides (nine)) were selected for this study. Regarding pesticide chemical groups, anilides (four active substances), neonicotinoids (three active substances), sulfonylureas (three active substances), and organophosphates (two active substances) are the most prominent. While less frequent, other chemical groups were also present (Table 2). These dominant families are recognized for their ecotoxicological impact [29].

According to the WHO hazard classification [54], these 24 active substances revealed a diverse risk profile. Approximately 29% of pesticide residues were categorized as moderately hazardous; slightly hazardous residues and those unlikely to present acute hazards were similar (25%), followed by those not listed (21%).

Table 2. List of twenty-four active substances analyzed and their physico-chemical properties, their biological activity, their toxicological properties, and the CLP classification [55,56].

Active Substances	Biological Activity a	Chemical Family	Toxicity Class (Who, 2020) b	CLP Classification c	DT50 d	Koc e	GUS f	Henry‘s Constant g	Kow h	LC50 Bees (mg/bee)	LC50 Worm (mg/kg)	LC50 Daphnia (mg/L)	EC50 Algae (mg/L)
Acetamiprid	I	Neonicotinoid	II	Health: H302 Environment: H412	3	200	0.94	5.30 × 10−08	0.8	0.0089	9	49.8	>98.3
Chlorantraniliprole	I	Diamide	U	Health: H319, H335 Environment: H400, H410	204	362	3.51	3.2 × 10−09	2.86	>0.004	>1000	0.0116	>2.0
Chlorpyrifos	I	Organophosphate	II	Health: H301 Environment: H400, H410	27.6	5509	0.58	0.478	4.7	0	129	0.0001	0.48
Chlorpyriphos Methyl	I, A	Organophosphate	III	Health: H317 Environment: H400, H410	1.24	4645	0.08	0.235	4.00	0	182	0.0006	0.57
Cyflufenamid	F	Amide	NL	Health: H332 Environment: H400, H410, H411	25.3	/	1.12	2.81 × 10−02	4.7	>0.1	>500	>1.73	>0.828
Cyprodinil	F	Anilinopyrimidine	III	Health: H317 Environment: H400, H410	45	/	1.06	6.60 × 10−03	4	>0.075	192	0.22	2.6
Dimethomorph	F	Morpholine	III	Environment: H411	44	/	2.26	2.5 × 10−05	2.68	>0.102	>500	>20.1	29.2
Epoxiconazole	F	Triazole	NL	Health: H351, H360Ddf Environment: H411	97.7		2.09	1.65 × 10−05	3.3	>0.1	>500	>3.13	>10.69
Flufenacet	H	Anilide	II	Health: H302, H317, H373 Environment: H400, H410	39	401	2.49	1.3 × 10−03	3.5	>0.109	219	30.9	0.00204
Fluopicolide	F	Benzamide	U	Environment: H400, H410	138.8	/	3.20	4.15 × 10−05	2.9	>0.1	>500	>1.8	0.029
Flupyradifurone	I	Organofluoride	II	Health: H302, H373 Environment: H400, H410, H412	130	98.4	4.24	8.2 × 10−08	1.2	>0.2	185.6	>77.6	>100
Imidacloprid	I	Neonicotinoid	II	Health: H302 Environment: H400, H410	174	/	3.69	1.7 × 10−10	0.57	0	10.7	85	>10
Isopropanil	H	Dinitroaniline	NL	Handling: H226 Environment: H400, H410	/	10,000	0.00	4.8	5.29	/	/	>0.022	/
Linuron	H	Urea	III	Health: H302, H351, H360Df, H373 Environment: H400, H410	48	842.8	2.11	2.00 × 10−04	3.0	0	>500	0.31	0.016
Metalaxyl	F	Anilide	II	Health: H302; H317 Environment: H412	14.1	162	2.06	1.60 × 10−05	1.75	>0.2	>1000	3.47	0.42
Metalaxyl- M	F	Anilide	NL	Heath: H302, H318	14.1	/	2.64	3.50 × 10−05	1.71	>0.1	830	>100	36
Metsulfuron methyl	H	Sulfonylurea	U	Environment: H400, H410	13.3	/	3.28	2.87 × 10−06	−1.87	0	>1000	>43.1	0.113
Penconazole	F	Triazole	III	H302, H361d, H400, H410	89.7	/	1.28	6.60 × 10−04	3.72	>0.003	>331.5	6.75	4.9
Simazine	H	Triazine	U	Health: H351 Environment: H400, H410	90	130	2.20	5.60 × 10−05	2.3	0	1000	1.1	0.04
S-metolachlor	H	Chloroacetamide	III	Health: H317 Environment: H400, H410	23.17	/	2.32	2.20 × 10−03	3.05	>0.2	570	11.2	0.017
Tetraconazole	F	Triazole	II	Health: H302, H332 Environment: H411	430	/	2.47	3.60 × 10−04	3.56	0.063	71	3	2.4
Thiamethoxam	I	Neonicotinoid	NL	Health: H302 Environment: H400, H410	39	56.2	3.58	4.70 × 10−10	−0.13	0	>1000	>100	>100
Triasulfuron	H	Sulfonylurea	U	Environment: H400, H410	38.5	60	4.59	8.00 × 10−05	−0.59	>0.1	>1000	>100	0.035
Tribenuron-Methyl	H	Sulfonylurea	U	Health: H317, H373 Human: H400, H410	3.6	35	1.39	1.00 × 10−08	0.38	0	>1000	894	0.11

a. I: insecticide, including A: acaricide, F: fungicide, H: herbicide, and N: nematicide. b. Ia: highly hazardous; Ib: extremely hazardous; II: moderately hazardous; III: slightly hazardous; U: unlikely to present acute hazard; NL: not listed. c. CLP: Classification Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on the classification, labeling, and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC and amending Regulation (EC) No 1907/2006 [57]. H300: fatal if swallowed; H301: toxic if swallowed; H302: harmful if swallowed; H310: fatal in contact with skin; H312: harmful in contact with skin; H315: causes skin irritation; H317: may cause an allergic skin reaction; H318: causes serious eye damage; H319: causes serious eye irritation; H330: fatal if inhaled; H331: toxic if inhaled; H332: harmful if inhaled; H335: may cause respiratory irritation; H340: may cause genetic defects (state the route of exposure if it is conclusively proven that no other routes of exposure cause the hazard); H351: suspected of causing cancer (state the route of exposure if it is conclusively proven that no other routes of exposure cause the hazard); H360: may damage fertility or the unborn child (state the specific effect if known) (state the route of exposure if it is conclusively proven that no other routes of exposure cause the hazard); H361: suspected of damaging fertility or the unborn child (state the specific effect if known) (state the route of exposure if it is conclusively proven that no other routes of exposure cause the hazard); H372: causes damage to organs (state all organs affected, if known) through prolonged or repeated exposure (state the route of exposure if it is conclusively proven that no other routes of exposure cause the hazard); H373: may cause damage to organs (state all organs affected, if known) through prolonged or repeated exposure (state the route of exposure if it is conclusively proven that no other routes of exposure cause the hazard); H400: very toxic to aquatic life; H410: very toxic to aquatic life with long-lasting effects; H411: toxic to aquatic life with long-lasting effects; H412: harmful to aquatic life with long-lasting effects. d. DT50: half-life in soil (days). e. Koc: soil sorption coefficient. f. GUS: groundwater ubiquity score; Kow: partition coefficient. g. Kh: Henry’s law constant; Kow: octanol–water partition coefficient. LC50: lethal concentration value. EC50: effective concentration 50.

Table 2. List of twenty-four active substances analyzed and their physico-chemical properties, their biological activity, their toxicological properties, and the CLP classification [55,56].

Active Substances	Biological Activity a	Chemical Family	Toxicity Class (Who, 2020) b	CLP Classification c	DT50 d	Koc e	GUS f	Henry‘s Constant g	Kow h	LC50 Bees (mg/bee)	LC50 Worm (mg/kg)	LC50 Daphnia (mg/L)	EC50 Algae (mg/L)
Acetamiprid	I	Neonicotinoid	II	Health: H302 Environment: H412	3	200	0.94	5.30 × 10−08	0.8	0.0089	9	49.8	>98.3
Chlorantraniliprole	I	Diamide	U	Health: H319, H335 Environment: H400, H410	204	362	3.51	3.2 × 10−09	2.86	>0.004	>1000	0.0116	>2.0
Chlorpyrifos	I	Organophosphate	II	Health: H301 Environment: H400, H410	27.6	5509	0.58	0.478	4.7	0	129	0.0001	0.48
Chlorpyriphos Methyl	I, A	Organophosphate	III	Health: H317 Environment: H400, H410	1.24	4645	0.08	0.235	4.00	0	182	0.0006	0.57
Cyflufenamid	F	Amide	NL	Health: H332 Environment: H400, H410, H411	25.3	/	1.12	2.81 × 10−02	4.7	>0.1	>500	>1.73	>0.828
Cyprodinil	F	Anilinopyrimidine	III	Health: H317 Environment: H400, H410	45	/	1.06	6.60 × 10−03	4	>0.075	192	0.22	2.6
Dimethomorph	F	Morpholine	III	Environment: H411	44	/	2.26	2.5 × 10−05	2.68	>0.102	>500	>20.1	29.2
Epoxiconazole	F	Triazole	NL	Health: H351, H360Ddf Environment: H411	97.7		2.09	1.65 × 10−05	3.3	>0.1	>500	>3.13	>10.69
Flufenacet	H	Anilide	II	Health: H302, H317, H373 Environment: H400, H410	39	401	2.49	1.3 × 10−03	3.5	>0.109	219	30.9	0.00204
Fluopicolide	F	Benzamide	U	Environment: H400, H410	138.8	/	3.20	4.15 × 10−05	2.9	>0.1	>500	>1.8	0.029
Flupyradifurone	I	Organofluoride	II	Health: H302, H373 Environment: H400, H410, H412	130	98.4	4.24	8.2 × 10−08	1.2	>0.2	185.6	>77.6	>100
Imidacloprid	I	Neonicotinoid	II	Health: H302 Environment: H400, H410	174	/	3.69	1.7 × 10−10	0.57	0	10.7	85	>10
Isopropanil	H	Dinitroaniline	NL	Handling: H226 Environment: H400, H410	/	10,000	0.00	4.8	5.29	/	/	>0.022	/
Linuron	H	Urea	III	Health: H302, H351, H360Df, H373 Environment: H400, H410	48	842.8	2.11	2.00 × 10−04	3.0	0	>500	0.31	0.016
Metalaxyl	F	Anilide	II	Health: H302; H317 Environment: H412	14.1	162	2.06	1.60 × 10−05	1.75	>0.2	>1000	3.47	0.42
Metalaxyl- M	F	Anilide	NL	Heath: H302, H318	14.1	/	2.64	3.50 × 10−05	1.71	>0.1	830	>100	36
Metsulfuron methyl	H	Sulfonylurea	U	Environment: H400, H410	13.3	/	3.28	2.87 × 10−06	−1.87	0	>1000	>43.1	0.113
Penconazole	F	Triazole	III	H302, H361d, H400, H410	89.7	/	1.28	6.60 × 10−04	3.72	>0.003	>331.5	6.75	4.9
Simazine	H	Triazine	U	Health: H351 Environment: H400, H410	90	130	2.20	5.60 × 10−05	2.3	0	1000	1.1	0.04
S-metolachlor	H	Chloroacetamide	III	Health: H317 Environment: H400, H410	23.17	/	2.32	2.20 × 10−03	3.05	>0.2	570	11.2	0.017
Tetraconazole	F	Triazole	II	Health: H302, H332 Environment: H411	430	/	2.47	3.60 × 10−04	3.56	0.063	71	3	2.4
Thiamethoxam	I	Neonicotinoid	NL	Health: H302 Environment: H400, H410	39	56.2	3.58	4.70 × 10−10	−0.13	0	>1000	>100	>100
Triasulfuron	H	Sulfonylurea	U	Environment: H400, H410	38.5	60	4.59	8.00 × 10−05	−0.59	>0.1	>1000	>100	0.035
Tribenuron-Methyl	H	Sulfonylurea	U	Health: H317, H373 Human: H400, H410	3.6	35	1.39	1.00 × 10−08	0.38	0	>1000	894	0.11

a. I: insecticide, including A: acaricide, F: fungicide, H: herbicide, and N: nematicide. b. Ia: highly hazardous; Ib: extremely hazardous; II: moderately hazardous; III: slightly hazardous; U: unlikely to present acute hazard; NL: not listed. c. CLP: Classification Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on the classification, labeling, and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC and amending Regulation (EC) No 1907/2006 [57]. H300: fatal if swallowed; H301: toxic if swallowed; H302: harmful if swallowed; H310: fatal in contact with skin; H312: harmful in contact with skin; H315: causes skin irritation; H317: may cause an allergic skin reaction; H318: causes serious eye damage; H319: causes serious eye irritation; H330: fatal if inhaled; H331: toxic if inhaled; H332: harmful if inhaled; H335: may cause respiratory irritation; H340: may cause genetic defects (state the route of exposure if it is conclusively proven that no other routes of exposure cause the hazard); H351: suspected of causing cancer (state the route of exposure if it is conclusively proven that no other routes of exposure cause the hazard); H360: may damage fertility or the unborn child (state the specific effect if known) (state the route of exposure if it is conclusively proven that no other routes of exposure cause the hazard); H361: suspected of damaging fertility or the unborn child (state the specific effect if known) (state the route of exposure if it is conclusively proven that no other routes of exposure cause the hazard); H372: causes damage to organs (state all organs affected, if known) through prolonged or repeated exposure (state the route of exposure if it is conclusively proven that no other routes of exposure cause the hazard); H373: may cause damage to organs (state all organs affected, if known) through prolonged or repeated exposure (state the route of exposure if it is conclusively proven that no other routes of exposure cause the hazard); H400: very toxic to aquatic life; H410: very toxic to aquatic life with long-lasting effects; H411: toxic to aquatic life with long-lasting effects; H412: harmful to aquatic life with long-lasting effects. d. DT50: half-life in soil (days). e. Koc: soil sorption coefficient. f. GUS: groundwater ubiquity score; Kow: partition coefficient. g. Kh: Henry’s law constant; Kow: octanol–water partition coefficient. LC50: lethal concentration value. EC50: effective concentration 50.

3.3. Environmental Risk Assessment Using PERI Model

The Environmental Risk Score for pesticides (ERS) was calculated for 24 active substances using all the components of the PERI model and the data collected.

Table 3. Environmental risk score for pesticides (ERS) calculated using the PERI model for twenty-four pesticide residues, using values of GUS, Kh, Kow, algae (A), bee (B), daphnia (D), and worm (W).

Active Substances	GUS Score	Kh Score	Kow Score	B Score	W Score	D Score	A Score	ER Score
Linuron	4	1	5	5	2	4	1	5.50
Tetraconazole	4	1	5	5	3	3	1	5.50
Chlorantraniliprole	5	1	1	5	1	5	1	5.30
Flupyradifurone	5	1	1	4	2	2	3	5.28
Imidacloprid	5	1	1	5	3	2	1	5.28
Fluopicolide	5	1	1	4	2	3	1	5.25
Epoxiconazole	4	1	5	4	2	3	1	5.25
Thiamethoxam	5	1	1	5	1	1	3	5.25
Metsulfuron methyl	5	1	1	5	1	2	1	5.23
Triasulfuron	5	1	1	4	1	1	1	5.18
Flufenacet	4	1	5	4	2	2	1	5.13
S-metolachlor	4	1	5	4	2	2	1	5.13
Cypridonil (cyprodinil)	3	1	5	5	2	5	1	4.63
Isopropanil (isopropalin)	1	2	5			5		4.50
Penconazole	3	1	5	5	2	3	1	4.38
Cyflufenamid	3	1	5	4	2	3	1	4.25
Simazine	4	1	1	5	1	3	1	4.25
Dimethomorph	4	1	1	4	2	2	1	4.23
Metalaxyl	4	1	1	4	1	3	1	4.23
Metalaxyl- M	4	1	1	4	2	1	1	4.20
Chlorpyrifos	2	1	5	5	2	5	1	3.63
Chlorpyriphos methyl	2	1	5	5	2	5	1	3.63
Tribenuron-methyl	3	1	1	5	1	1	1	3.20
Acetamiprid	2	1	1	5	4	2	1	2.30

presents scores in ascending order of ERS, ranging from 2.30 to 5.50. Therefore, twelve active substances have a High Environmental Risk (Score ≥ 5): linuron, tetraconazole, chlorantraniliprole, flupyradifurone, imidacloprid, fluopicolide, epoxiconazole, thiamethoxam, metsulfuron methyl, triasulfuron, flufenacet, and s-metolachlor. These pesticides have a high potential to cause harm to the environment.

The use of bold formatting in the table footer was intentional to highlight the ER Score, as it represents the final result calculated based on the other parameters

Several factors may contribute to these high values and may have long-term implications for the environment and human health. Consequently, improper application methods can result in uneven pesticide distribution, creating areas with higher concentrations. Additionally, weather conditions can influence the dispersion and degradation of pesticides, potentially leading to elevated concentrations under unfavorable conditions. In addition, some pesticides persist in the environment for a long time, leading to a gradual accumulation of residues. Different formulations of the same pesticide may have different physicochemical properties, resulting in higher concentrations under certain conditions.

According to the PERI model, the two active substances (linuron and tetraconazole) have the highest ER scores. Linuron, a broad-spectrum herbicide, has significant impacts on soil, aquatic ecosystems, and beneficial insects. It persists in soil, exhibiting slower dissipation rates in sludge-rich soils compared to natural soils [58]. At higher doses, it disrupts the nitrogen cycle by enhancing substrate-induced respiration and ammonification rates while simultaneously reducing nitrate concentrations [59]. Additionally, linuron negatively impacts microbial communities [60] and raises concerns regarding its long-term ecological consequences. Studies report increased mortality in honeybees [61], reduced pollination efficiency in bumblebees [62], and adverse effects on butterfly survival and longevity [63,64], underscoring its broad ecological risks.

As a fungicide, tetraconazole has significant long-term effects on both soil and aquatic ecosystems, primarily impacting microbial communities and overall ecological stability. Its persistence leads to changes in microbial diversity [65,66] and functions [67,68], disrupting vital ecological processes. Similarly, it affects microbial biomass and diversity, impairing soil functions [65,69]. Consequently, it negatively impacts soil enzyme activities [69,70]. Among non-target arthropods, tetraconazole poses an acute toxicological risk and has chronic and sublethal effects, particularly on reproduction, which is crucial for understanding the long-term effects on beneficial populations [71].

Tetraconazole, which received a high Ecotoxicological Risk Score (ERS = 5.5), is a triazole fungicide known to adversely affect soil microbial diversity, enzyme activities, and nutrient cycling processes, as documented in multiple laboratory studies [65,66,67,68,69,70,71]. These findings support its classification as a high-risk substance. However, its environmental behavior can vary significantly from one region to another, particularly in arid and semi-arid areas, such as those in Tunisia, where local climatic and edaphic conditions may slow its degradation and prolong its persistence in the soil.

Comparing the results obtained in this study with those from previous research, significant differences and consistencies emerge regarding the environmental risk scores (ER scores) and the active substances monitored. For instance, Soudani et al. [29] identified eighteen active substances with ER scores ranging from 1.28 to 6.13, of which six substances exceeded the eco-risk threshold of 5, indicating high environmental hazards. Although fewer substances were identified, the broader range of eco-risk scores suggests that individual substances may present significant environmental risks. Similarly, Muhammetoglu et al. [28] investigated seventeen active substances, with ER scores ranging from 1.20 to 5.75, and three substances surpassed the high-risk threshold. In this case, the narrower range of ER scores implies a more concentrated environmental impact associated with a smaller number of substances. On the other hand, the study by Recchia et al. [72], based on the PERI model for vineyard management in 2004 and 2010, examined twelve active substances, but the ER scores ranged from 0.59 to 5.23, with only two substances crossing the high-risk threshold. This suggests a relatively lower overall environmental impact compared to the other studies.

Overall, while each study identifies various substances with significant environmental risks, the differences in the number of substances monitored and the range of ER scores underscore the variability in environmental risk assessments. The present study covers a broader spectrum, potentially offering a more comprehensive evaluation that includes a wider range of high-risk substances. In contrast, previous studies like those of Soudani et al. [29] and Muhammetoglu et al. [28] emphasize fewer but potentially more hazardous substances, whereas Recchia et al. [72] indicate a relatively lower overall environmental risk.

Therefore, the results of the PERI model offer valuable insights into the importance of selecting pesticides with the least potential impact on soil and the environment, thereby aiding farmers and policymakers in reducing pesticide use.

3.4. Monitoring of Pesticide Residues in Soil and Water (Surface and Groundwater)

Monitoring pesticide residues in water and soil is essential to assess environmental contamination and evaluate risks to ecosystems. The pesticide levels and the number of active substances were determined from 15 samples of water (groundwater and surface water) and 15 samples of soil. Analysis of pesticide in water samples from wells (with depths between 6 m and 100 m) and river samples has revealed that 100% of the samples are contaminated by at least three pesticides. Additionally, the analysis of soil samples taken around these rivers and wells indicates that almost all samples (93%) contain at least one pesticide. Twelve and nine pesticides were detected in the most contaminated water and soil samples, respectively. The total concentrations of quantified pesticides range from 0.12 to 9.37 µg/L for water samples and from 0.93 to 1718.42 µg/kg for soil samples (

Table 4. Total number of detected and quantified active substances and total concentration of quantified pesticide residues per sample in water (ten well water samples and five river water samples) and in soil samples.

Sample		Water			Soil
		Depth (m)	Number of Active Substances Detected (Quantified)	Total Pesticide Concentration (µg/L)	Number of Active Substances Detected (Quantified)	Total Pesticide Concentration (µg/kg)
Wells	1	80	13 (7)	2.81	1 (1)	166.60
	2	100	13 (7)	1.08	4 (0)	0.00
	3	24	9 (4)	1.04	0 (0)	0.00
	4	25	10 (4)	0.58	3 (3)	16.25
	5	90	11 (5)	1.50	9 (4)	78.16
	6	20	5 (3)	7.87	7 (5)	256.82
	7	80	8 (6)	4.94	9 (6)	284.43
	8	6	6 (3)	0.95	3 (1)	0.93
	9	7	9 (5)	9.37	4 (1)	1718.42
	10	26	8 (6)	2.73	3 (0)	0.00
Rivers	11	-	8 (4)	7.62	1 (0)	0.00
	12	-	7 (5)	8.28	5 (1)	3.87
	13	-	3 (3)	0.38	1 (0)	0.00
	14	-	4 (4)	0.12	3 (0)	0.00
	15	-	9 (8)	0.16	5 (1)	1.07

). These results align with previous research on pesticide values, which have shown similar concentrations in both water and soil samples in the vineyard area of La Rioja (Spain) [73] and in groundwater of a hilly vineyard area in Val Tidone (Italy) [30]. Furthermore, the range of pesticide concentrations found in soil samples is in agreement with those reported in Nepal’s soil, ranging from 1.0 µg/kg to 1000 µg/kg [11]. However, the upper concentrations in soil, particularly those above 1000 µg/kg, may suggest potential environmental concerns.

Pesticide residues in water may come from agricultural runoff or atmospheric deposition and could be a result of intensive agricultural activities and inadequate management practices [74]. The water samples from well 9 and the corresponding soil near this well have the highest concentrations in soil (1718.42 µg/kg) and water (9.37 µg/L) samples. The significantly higher concentration in the soil sample raises concerns about potential toxicity to soil organisms, plant health, and the possibility of leaching into groundwater.

The concentrations of quantified pesticides in soil and water can vary significantly based on several factors, including the farmer’s attitude, local agricultural practices, variations in well depth [74], the physicochemical properties of the active substances, and environmental conditions [75,76].

Different pesticides were detected in water samples from wells, rivers, and soil samples. Out of 24 different active substances (a.s.), 18 (75%) and 15 (63%) pesticides were detected in almost all samples of water and soil, respectively (

Table 5. Alphabetic classification of all pesticide residues detected in water and soil samples with their number of detection (N), frequency (F), biological activity (BA = F (fungicide), H (herbicide), I (insecticide)), and the range of concentrations (R) in the samples.

BA	Pesticide Residues	Water Samples (n = 15)			Soil Samples (n = 15)
		N(F)		R in µg/L	N(F)	R in µg/kg
		Rivers (n = 5)	Wells (n = 10)
F	Cyflufenamid	5 (100%)	8 (80%)	[<LOD–0.012]	3 (20%)	[<LOD–1.500]
	Cypridonil	3 (60%)	8 (80%)	[<LOD–0.008]	4 (27%)	[<LOD–3.600]
	Dimethomorph	1 (20%)	7 (70%)	[<LOD–0.013]	-	-
	Epoxiconazol	0	2 (20%)	[<LOD–<LOQ]	1 (7%)	[<LOD–2.777]
	Fluopicolide	0	1 (10%)	[<LOD–<LOQ]	1 (7%)	[<LOD–<LOQ]
	Metalaxyl	0	9 (90%)	[<LOD–<LOQ]	7 (47%)	[<LOD–<LOQ]
	Metalaxyl- M	1 (20%)	10 (100%)	[<LOD–<LOQ]	10 (67%)	[<LOD–<LOQ]
	Penconazole	4 (80%)	9 (90%)	[<LOD–0.053]	4 (27%)	[<LOD–7.300]
	Tetraconazole	-	-	-	-	-
H	Flufenacet	-	-	-	4 (27%)	[<LOD–<LOQ]
	Isopropanil	-	-	-	-	-
	Linuron	3 (60%)	4 (40%)	[<LOD–7.795]	6 (40%)	[<LOD–1718.424]
	Metsulfuron-Methyl	-	-	-	2 (13%)	[<LOD–2.628]
	Simazine	2 (40%)	0	[<LOD–<LOQ]	3 (20%)	[<LOD–0.934]
	S-Metolachlor	3 (60%)	6 (60%)	[<LOD–<LOQ]	6 (40%)	[<LOD–<LOQ]
	Triasulfuron	0	1 (10%)	[<LOD–<LOQ]	-	-
	Tribenuron-Methyl	1 (20%)	0	[<LOD–0.014]	-	-
I	Acetamiprid	5 (100%)	9 (90%)	[<LOD–3.405]	-	-
	Chlorantraniliprole	0	1 (10%)	[<LOD–<LOQ]	-	-
	Chlorpyrifos	0	2 (20%)	[<LOD–0.007]	3 (20%)	[<LOD–<LOQ]
	Chlorpyriphos Methyl	0	1 (10%)	[<LOD–<LOQ]	-	-
	Flupyradifurone	2 (40%)	9 (90%)	[<LOD–7.821]	2 (13%)	[<LOD–231.100]
	Imidacloprid	-	-	-	2 (13%)	[<LOD–1.071]
	Thiamethoxam	-	-	-	-	-

). Sixteen pesticides were detected in the well samples (with an average of 5.1 a.s. per sample), and 11 a.s. in the river samples (with an average of 1.72 a.s. per water sample). For the well samples, seven active substances were detected, with percentages ranging from 80% to 100%. These substances included metalaxyl-M, acetamiprid, penconazole, flupyradifurone, metalaxyl, cyflufenamid, and cyprodinil. In the river samples, three a.s. (acetamiprid, cyflufenamid, and penconazole) were most often detected, with percentages greater than or equal to 80%. The insecticide acetamiprid and the two fungicides, cyflufenamid and penconazole, were detected in the majority of samples from both rivers and wells (Table 5). The presence of these active substances (acetamiprid, cyflufenamid, and penconazole) in the majority of samples from rivers and wells is considered an alarming result. These findings are consistent with other studies conducted worldwide.

Regarding the acetamiprid compound, Zhou et al. [77] detected higher concentrations in plantation sources compared to the surface waters of Taihu Lake in the Wujin District, China. The presence of acetamiprid was also reported in lake water in Vietnam [78]. Moreover, Tan et al. [79] found acetamiprid in more than 12.5% of surface water samples from river basins draining areas with rice–legume rotations in tropical China at concentrations exceeding 0.1 μg/L. In Turkey’s Büyük Menderes River, the insecticide acetamiprid was among the most frequently detected pesticide residues, exceeding the established limit values [80]. Additionally, macadamia orchard reservoirs have been heavily contaminated with acetamiprid, with an average concentration of 14.48 μg/L, which could negatively impact water quality and ecosystem function [81].

As for cyflufenamid, Zhang et al. [82] showed that PAOs (pesticides for agricultural use) such as this substance mainly come from agricultural and mariculture wastewater. Investigations carried out in South Africa, in the Western Cape [83], and in Spain, in the vineyards of La Rioja [84], indicate that penconazole is the most frequently detected fungicide in surface water and groundwater samples. In Argentina, Medina et al. [85] detected concentrations of penconazole ranging from 0.01 to 0.02 μg/kg. Concerning metalaxyl-M, the assessment of the environmental impact of the use of PPPs in peri-urban agriculture in Togo, carried out by Kanda et al. [86], revealed the highest levels of contamination in water samples (1.1 μg/L). In Italy, Suciu et al. [13] reported that metalaxyl-M was the only pesticide detected in all the wells at concentrations exceeding the limit of quantification (LOQ), while penconazole was the second most commonly detected plant protection product (PPP).

The soil constitutes an off-site reservoir for the release of farmland pesticides. However, pesticide residues in the soil can pose serious hazards to the ecosystem and its biota. Fifteen active substances (approximately 62% of the tested pesticides) representing different pesticide groups were detected in almost all soil samples, with an average of four pesticide residues per sample. The most prominent and detectable residues were metalaxyl-M (67%), metalaxyl (47%), linuron (40%), and s-metolachlor (40%). In contrast, nine active substances (approximately 37% of the tested pesticides) were not detected. These undetected residues included triasulfuron, thiamethoxam, acetamiprid, chlorantraniliprole, chlorpyrifos-methyl, dimethomorph, tribenuron-methyl, isopropanol, and tetraconazole.

Metalaxyl and metalaxyl-M are systemic fungicides widely used in agriculture to combat various fungal diseases in plants caused by Oomycete fungi [87,88]. Metalaxyl and metalaxyl-M have moderate mobility in the soil and can persist for several weeks or even months, depending on the conditions [89]. Although pesticide residues (metalaxyl and metalaxyl-M) are the most frequently detected, their concentrations are not quantifiable, as they are below the limit of quantification (LOQ). In contrast, another study conducted on vineyard soils reported that metalaxyl is among the pesticide residues with a high concentration, specifically 11.5 μg/kg [90].

The concentration levels of the analyzed pesticides in soil samples ranged from below the limit of quantification (<LOQ) to 1718 μg/kg (Table 5). The herbicide linuron exhibits the highest concentration among the substances tested. Linuron was detected six times (40%), with quantified concentrations varying significantly from 3.7 to 1718 μg/kg. Therefore, the presence of high concentrations of linuron in the soil was not surprising, as it has a strong binding capacity with organic carbon in sediments [91].

Similar to linuron, s-metolachlor is a widely utilized herbicide for managing annual grasses and small-seeded broadleaf weeds in over 70 agricultural crops globally [92]. This herbicide can contaminate the soil through various pathways, including direct application, runoff, and leaching. The extent of contamination is influenced by factors such as soil type, organic matter content, rainfall, and application rates [92,93]. Gasmi et al. [94] have indicated that s-metolachlor, which is authorized for use in cereals, is the origin of non-point source pollution.

In addition, one herbicide (metsulfuron-methyl) and two insecticides (imidacloprid and flupyradifurone) were detected two times, with maximum concentrations of 2.6, 1.1, and 231.1 µg/kg, respectively. Concerning metsulfuron-methyl, a widely used sulfonylurea herbicide, it is valued for its selectivity against various weeds in cereal, pasture, and plantation crops [95]. According to Necibi et al. [96], the levels of mesosulfuron-methyl detected in this survey of the surface waters of the Migirda River were below detection limits at all sampling locations. In contrast, research by Maznah et al. [96] shows that metsulfuron-methyl can be classified among leachable substances across all soil horizons, with its adsorption coefficient (KOC) varying by soil type, impacting its persistence and leaching capacity. In rice fields under tropical conditions, as noted by Sondhia et al. [95], metsulfuron-methyl’s persistence is low, though it can be mineralized by microbial activity once in the soil. When applied at 15 g a.i./ha, about 72.23% of the residues were found in the top 10 cm of soil. Studies report that the half-life of metsulfuron-methyl in three tropical agricultural soils was significantly shorter at the recommended application rate than at double the rate; thus, a portion reaches deeper layers within a short time after application [97,98]. Therefore, the rising use of metsulfuron-methyl raises concerns about its potential to contaminate groundwater.

Also, the neonicotinoid imidacloprid is a widely used insecticide that poses a significant environmental risk due to its high persistence and leaching potential [99,100]. Despite its adsorption capacity, imidacloprid’s long half-life and its tendency to accumulate in the soil present a higher risk of contamination than short-term leaching [100,101]. Thus, concerns over this compound are escalating, and its monitoring in soil is required to assess its influence on soil health and non-target species [100].

Pesticide residue analysis revealed the presence of epoxiconazole with a concentration of 2.8 µg/kg. Epoxiconazole is a broad-spectrum fungicide used to combat diseases caused by ascomycetes, basidiomycetes, and deuteromycetes [102,103]. In Tunisia, Salem [104] compared sold pesticides and used pesticides in the Ichkeul Lake–Bizerte lagoon watershed (Tunisia), and the differences in favor of what was used seemed larger for epoxiconazole (7350/17,168 kg). Furthermore, Mhadhbi et al. [105] used the POCIS method and found that epoxiconazole was among the most frequently detected and quantified ingredients across all study sites. For the same compound, Necibi et al. [96] detected a value of 5.14 µg/L when they assessed the surface water quality of the Majarda River.

Medić Pap et al. [106] reported the presence of epoxiconazole (0.13 ± 0.42 μg/kg) in 14% of Serbian agricultural soil samples. Moreover, it is one of the most prominent pesticides found in European soils and has been recorded in Swiss and French regions [107]. However, applying this compound to agricultural fields at high concentrations entails a significant risk to the environment [103]. Some studies have indicated slow degradation and incomplete mineralization of epoxiconazole in wetland conditions (with a half-life ranging from 52 to 354 days) [96] and in anoxic conditions under buffer zone substrates [108]. Epoxiconazole is considered potentially toxic and can have harmful effects on soil microbial ecology [109] and earthworm populations, and it may cause a decline in biodiversity if exposure occurs over the long term [110].

Once pesticides enter the soil, they can volatilize, leach, adsorb onto soil particles, and degrade chemically and biologically [111]. Notably, pesticide residues undergo long-term changes, thus varying in concentration when samples are collected [112]. Furthermore, adsorption/desorption processes have a significant influence on the regulation of the contaminant’s concentration in the soil solution, its transport to waters, bioavailability, and degradation [113]. Pesticide bioaccumulation in sediment is driven by factors beyond the soil, such as fertility, pH, temperature, and the hydrophobic interactions of pesticides with sediment [114]. Most assuredly, the buildup and persistence of these pesticides can disrupt microbial activity [115] and pose a long-term threat to benthic communities and aquatic ecosystems.

To better assess the potential ecological risks, the concentrations of detected pesticides in both water and soil samples were compared to chronic ecotoxicological thresholds (NOEC values) for representative non-target organisms in each environmental compartment. For aquatic environments, NOEC values were primarily based on standard test species such as Oncorhynchus mykiss and Pimephales promelas (temperate freshwater fish), and Daphnia magna (aquatic invertebrates). For terrestrial environments, NOEC values were considered for Eisenia fetida (earthworms) and Folsomia candida (Collembola), which are commonly used as indicators of soil health. Although several pesticides were detected in water and soil samples, their concentrations remained below the chronic NOEC values for non-target aquatic and terrestrial organisms (Supplementary Information, Table S2). Among all detected pesticides, linuron exhibited the highest concentrations in both water (up to 7.795 µg/L) and soil (up to 1718 µg/kg). However, these levels remain well below chronic toxicity thresholds for non-target organisms. In water, the maximum concentration is approximately 23 times lower than the NOEC for freshwater invertebrates (Daphnia magna, 180 µg/L). In soil, linuron levels are about four times lower than the NOEC for earthworms (Eisenia fetida, 6780 µg/kg) and thirty-three times lower than that for springtails (Folsomia candida, 57.060 mg/kg) [55] (Supplementary Information, Table S2). These findings suggest that, despite its relatively high occurrence, linuron poses limited ecological risk under the observed conditions.

Interestingly, on 13 July 2023, the Tunisian supervisory authority at the Ministry of Agriculture and Fisheries issued a statement ordering the withdrawal and prohibition of some substances classified as Highly Hazardous Pesticides (HHPs) from the market or circulation due to their unsafe use and toxicity to consumers and the environment. Therefore, the findings of this study have also identified five active substances prohibited in many countries, including the European Union. These substances are epoxiconazole, imidacloprid, linuron, thiamethoxam, and triasulfuron. Fortunately, the General Directorate for Plant Health and Control of Agricultural Inputs is closely monitoring regulatory developments and regularly reviewing the active ingredients authorized in Tunisia, representing a positive step toward ensuring safer agricultural practices and protecting the environment.

This study provides valuable insight into pesticide occurrence in the water and soil of Kef governorate and the potential environmental impact. However, certain limitations should be acknowledged to contextualize the findings. The sample size, while sufficient to offer an initial assessment, was limited to fifteen primary sites without biological replicates, which may constrain the detection of spatial variability within the sites. Site selection was based on accessibility and prior knowledge, ensuring relevance but potentially introducing selection bias. The study focused on a single sampling campaign, providing a snapshot rather than temporal trends in pesticide occurrences. Future research would benefit from expanding the number of sampling sites, including biological replicates to capture within-site variability, implementing repeated temporal sampling to assess seasonal dynamics, and integrating chronic toxicity metrics for a more comprehensive risk evaluation. These enhancements would complement the current findings and strengthen the overall understanding of pesticide exposure in the region.

4. Conclusions

This study revealed the presence of various pesticides in surface and groundwater, as well as in soil with varying concentrations. The detection of these contaminants in multiple environmental compartments suggests extensive pollution, which could threaten both ecosystems and public health. Several factors may explain this contamination. The investigation with farmers highlighted the presence of water points located directly adjacent to treated fields, which could contribute to pesticide runoff. Additionally, improper pesticide management may also be a contributing factor. Regarding regulation governing pesticide use, Tunisia has made significant progress in addressing this issue compared to other developing countries, actively updating its regulations and eliminating some of the most dangerous pesticides from the market. These advancements underscore the country’s ongoing efforts to mitigate environmental and public health risks linked to pesticide exposure.

To further strengthen these efforts, the implementation of regular monitoring programs is recommended, with at least annual sampling of soil and water resources, especially in high-risk agricultural zones. Particular attention should be paid to the surveillance of high-risk pesticides, such as linuron and tetraconazole, which exhibit significant residue levels in this study.

Additionally, it is crucial to strengthen monitoring systems and promote alternative agricultural practices, such as integrated pest management. Equally important is the need to raise awareness among farmers about the risks associated with pesticide misuse and to provide targeted training on safer application techniques and sustainable alternatives.

Ongoing scientific research and regular updates to national regulations will be essential to support long-term agricultural sustainability and minimize associated environmental and health hazards.