Microplastics (MPs) in sediments from the complex lagoon-channel of Bizerte were investigated, for the first time, to evaluate the occurrence and abundance of MPs in Tunisia. After density separation in saline solution, MPs were counted by a stereomicroscope. The number of MPs was at the range of 3–18 items/g sediment (3000–18,000 items/kg dry sediment) and the most contaminated site was of Menzel Abderrahmane (MA) followed by Carrier Bay (CB), Menzel Jemil (MJ) and Channel of Bizerte (C). The MPs gathered during the survey varied in size from 0.3 to 5 mm, and appear in a variety of shapes and colours. The dominant shape was fibre (88.88% in MA, 91.00% in CB, 82.35% in C and 21.05% in MJ). The rest of MPs are fragments whilst no micro beads were found. Colours are clear, white, blue, green, red and black. Cities discharges, fishing activity and industrial production sites are the most likely sources of MPs. This first work provides original data on the presence of MPs that determines their bioavailability to organisms as seafood, and then possibly transfers of to human. The high MP concentrations registered in the complex lagoon-channel of Bizerte suggest that this site is a hotspot for MP pollution and there is an urgency to understand their origins and effects on marine life. The results will provide useful background information for further investigations.

In this study, a process has been proposed whereby the sulfide required for autotrophic denitrification is supplied by reducing the sulfate of influent water without the need to add an external sulfide source. The molar ratio of nitrate-to-sulfide was maintained at 1.6. The proposed system was operated continuously for 6 months, including two anoxic and anaerobic reactors with upward flow. The results indicate that the average amount of nitrate declined by 74%. The pH of 7–8 was more effective than a pH of 6 in removing the nitrate. As the hydraulic retention time was prolonged from 1.5 to 3 and was further prolonged to 5 h, the system efficiency was enhanced by removing the nitrate. An alkalinity consumption rate of 1.15 mg (as CaCO₃) per mg of removed NO₃ ⁻-N was achieved. In the effluent water, the increased sulfate was 6.7 mg per mg of removed NO⁻ ₃-N, while the hardness was diminished by 2.85 mg (as CaCO₃).

Cadmium and lead are some of several heavy metals that present a great concern for the environment because even in non-toxic concentrations for plants, their toxicity can affect animals and humans. Three different concentrations of sodium chloride solution were employed as pretreatment agents in order to increase the bioavailability of heavy metals and to analyze the interaction between heavy metals under saline soil conditions. The biomass production presented a remarkable increase for plants grown in soil pretreated with a 0.3 M NaCl solution, whereas the growth curve response of Arabidopsis thaliana in all samples showed a clear alteration compared with the control system. The conclusion was reached that saline solution pretreatment used in soil containing heavy metals produced an apparent stimulation of plant growth. In regards to the uptake of heavy metals by plants, lead and especially cadmium were the most favored metals by NaCl application.

Diclofenac (hereafter DCF) is an extensively used anti-inflammatory drug; therefore, it is found in many sewage treatment plant effluents and it is one of the most usually reported environmental pharmaceutical contaminants. In this work, the degradation of diclofenac in pure water under UV light was studied, and the influence of some variables, such as humic acids (HA), nitrate anions (NO₃⁻) and titanium dioxide (TiO₂) on DCF photodegradation was investigated. The experimental activity was carried out in a batch reactor of 100 mL equipped with fixed UV light of 254 nm and an irradiation intensity of 400 mJ/m². Diclofenac initial concentration was equal to 10 mg/L in pure water, and its removal was evaluated by varying HA concentration in the range 10–20 mg/L and NO₃⁻ concentration in the range 25–50 mg/L. Furthermore, the heterogeneous catalysis with TiO₂ (1–50 mg/L) was studied. Temperature in all experiments was kept constant at 20 °C. Experimental results show that while HA have a significant influence on DCF photodegradation, nitrate and titanium dioxide seem to be ineffective, at least in the tested conditions. Finally, DCF photolysis modelling was carried out and a pseudo-first-order kinetic model was used.

Nowadays, the increasing pollution of natural water effluents with surfactant, wetting, dispersing, and emulsifying agents which contain nonylphenol ethoxylate (NP₇EO) is an emerging problem that has not received the enough attention. Currently, it is known that degrading this type of highly stable compounds is possible through advanced electrochemical oxidation (AEO), but the degradation of NP₇EO has not been tested yet. Thus, this work carries out a study of the degradation of the NP₇EO (500 mg L⁻¹) through advanced electrochemical oxidation, using a DiaClean® cell, equipped with boron-doped diamond electrodes (BDD, 70 cm²). The cell operated in a recirculation system with a peristaltic pump, which allowed to control the electrolyte flow. The buffer media for degradation was NH₄OH 0.1 M/HCl 0.05 M (pH 9.25). The effect of the current density (j = 20, 30, 40 mA cm⁻²) was studied, and the cell efficiency for each condition was evaluated. The degradation was followed by total organic carbon (TOC), chemical oxygen demand (COD), and absorbance. The cell potential was monitored to determine the operating costs. The best conditions for the mineralization of NP₇EO (initial concentration = 500 mg L⁻¹) were applying 40 mA cm⁻² and at a flow rate of 12.6 L min⁻¹ during 8 h of electrolysis, achieving a 90% of TOC removal. Therefore, this technology appears as a promising alternative for degrading surfactants like NP₇EO in aqueous media.

To evaluate the exposure of children to 14 perfluorinated compounds (PFCs) in a typical and representative industrial city, plasma samples from 476 children aged 0–7 years in Foshan, China, were analysed. Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were detected in 100% of the samples, accounting for 82.27 and 11.46% of the total PFC concentrations, respectively, while PFOS peaked at age 0–1 years, for which the mean and median concentrations were 113.71 and 83.65 ng/mL, respectively, while PFOA peaked at age 3–4 years, for which the mean and median concentrations were 10.68 and 6.58 ng/mL, respectively. The concentrations of PFOS, perfluorohexane sulfonate and perfluorohexanoic acid decreased with age among children aged 0–7 years, and no gender-related differences were found in the concentrations of PFCs. A high correlation was found among all PFCs, especially between PFCs of similar carbon chains (r = 0.161–0.695, p < 0.05). In addition, the concentrations of PFOS and PFOA in children’s plasma in Foshan were up to 40-fold higher than those reported in China and other countries. In conclusion, children in Foshan have extensive exposure to PFCs, especially in infancy. Further studies are needed to explore the impact of PFCs on children who live in a typical and representative industrial city in China. Graphical abstract ᅟ

Due to intensive agricultural activities to meet the growing needs for food, large volumes of water are consumed and an increasing amount of agrochemicals are released into the environment threatening the aquatic ecosystem. In order to ensure a sustainable agricultural management, it is crucial to develop an integrated water assessment plan that includes not only water quantity and quality but also toxicological assessments. The Pergamino River basin (province of Buenos Aires, Argentina) was selected as a representative case of study to monitor and assess the impact of both the long-term intensification of soybean production and fast-growing urban development on surface and groundwater sources. Physicochemical analyses and a Water Quality Index were determined and showed that water quality falls into the marginal category, compromising the irrigation purposes and threatening aquatic life. Glyphosate and aminomethylphosphonic acid were detected at least once in all sites. Caenorhabditis elegans toxic bioassays were performed and a toxicological ranking was developed. This analysis proved to be useful to detect toxicity even when water parameters met regulatory requirements and water quality seemed to be satisfactory. This research constitutes a valuable model to be replicated in other river basins that have been impacted by intensive agriculture and growing urban development in order to assess water quality conditions and ensure sound water resources management.

The sorption of three organic contaminants with different structure and polarity including non-polar phenanthrene (PHEN), 1,2,4,5-tetrachlorobenzene (TeCB), and polar 1,2-dichlorobenzene (DCB) onto original kaolinite, smectite, vermiculite, and fulvic acid (FA)/humic acid (HA)–clay complexes were investigated, and possible sorption mechanisms were inferred from sorption isotherms and characteristics of humic substances (HS) and HS–mineral complexes. Results showed smectite and vermiculite had stronger sorption ability than kaolinite, and the adsorbed amount of DCB was much higher than that of PHEN and TeCB on each clay. Due to FA/HA-facilitated hydrophobic interaction, FA/HA–clay complexes except FA–vermiculite complex showed a stronger affinity for PHEN and TeCB than the original clays, particularly for HA–clay complexes. The non-linearity parameter values of n for all the Freundlich sorption isotherms of DCB were greater than 1, indicating that clays possessed some unique sites with strong affinity and capacity to sorb DCB from aqueous solutions. FA/HA did not significantly affect the sorption of polar DCB on clays, implying sorption of DCB on clays was probably due to polar interactions between the polar group of DCB and clays. Cation-π bonding between PHEN and iron cation was directly evidenced by X-ray photoelectron spectroscopy, and FA impeded the sorption of PHEN on vermiculite by occupation of iron cation sites. This study will benefit understanding behaviors of contaminants in the soil environments.

Treated wastewater (TWW) is an imperative nonconventional water resource for reuse in irrigation to cope with the water shortage and agricultural expansion in Egypt. The Bahr El-Baqar drain in Sharqia, Egypt, is one of the main drains in the Nile Delta that receives various types of wastewater. Monitoring and assessing the drain’s water quality were achieved by collecting georeferenced water samples along the drain during the 2015 summer and winter cropping seasons. Chemical, microbial, and parasitic analyses were performed. Additionally, surface soil samples irrigated with the drain water were gathered from the adjacent area to quantify the main physicochemical properties. Water analysis results revealed that the concentrations of most trace elements were within international standards and the Egyptian allowable levels for TWW reuse in agriculture. Oxygen depletion was observed for all samples collected. The microbial analysis indicated that there was fecal coliform contamination (>1000 per 100 mL) in the summer and winter samples. Concentrations of PO₄ and SO₄ were within the permissible level for irrigation use, whereas NH₄, NO₃, and MoO₄ concentrations were higher than the recommended values for reusing Bahr El-Baqar water in irrigation. Based on the soil analysis results, Cd contamination was observed, whereas the Pb concentration in soils was slightly higher than its normal range. Mixing Bahr El-Baqar water with freshwater and implementing appropriate on-farm treatment before the reuse are recommended as a prerequisite for reusing Bahr El-Baqar water for irrigation. Bio-diesel fuel and energy oil crops are recommended for the studied region.

A quantitative microbial risk assessment method can be used to evaluate infections probabilities for microorganisms in a specific place. The methodology provides suitable information to generate strategies focusing on health problems. Giardia cysts (GC) and Cryptosporidium oocysts (CO) are considered emerging pathogens that can infect human and animals by ingesting contaminated food or water, where food and water are transport vehicles for these parasites. Studies for GC and CO have reported occurrences for these parasites in water up to 100%, and some of these studies documented a number of cases, about 403,000 people, infected worldwide. This review is focused on compiling the most relevant works assessing the risk for GC and CO and their presence in different water samples that are susceptible for direct and indirect human consumption. The annual risk infection probability for these parasites has been reported from different water sources, with a range between 1 × 10⁻⁶ and 1, while the world standard regulation is 1 × 10⁻⁴. The infection probability depends not only on water quality but also on water treatment implementations.