Tunis Gulf (northern Tunisia, Mediterranean Sea) is of great economic importance due to its abundant fish resources. Rising urbanization and industrial development in the surrounding area have resulted in an increase in untreated effluents and domestic waste discharged into the gulf via its tributary streams. Metal (Cd, Pb, Hg, Cu, Zn, Fe, and Mn) and major element (Mg, Ca, Na, and K) concentrations were measured in the grain fine fraction <63 μm by atomic absorption spectrophotometry. Results showed varying spatial distribution patterns for metals, indicating complex origins and controlling factors such as anthropogenic activities. Sediment metal concentrations are ranked as follows: Fe > Mg > Zn > Mn > Pb > Cu > Cd > Hg. Metals tend to be concentrated in proximity to source points, suggesting that the mineral enrichment elements come from sewage of coastal towns and pollution from industrial dumps and located along local rivers, lagoons, and on the gulf shore itself. This study showed that trace metal and major element concentrations in surface sediments along the Tunis Gulf shores were lower than those found in other coastal areas of the Mediterranean Sea.

Four heavy metals (Cd, Cu, Pb and Zn), two metalloids (As and Sb) and two rare metals (In and Tl) were selected as target elements to ascertain their concentrations and accumulation in the soil-plant system and their effects on the structure of the soil microbial community in a typical area of rare metal smelting in south China. Twenty-seven soil samples 100, 500, 1000, 1500 and 3000 m from the smelter and 42 vegetable samples were collected to determine the concentrations of the target elements. Changes in soil micro-organisms were investigated using the Biolog test and 454 pyrosequencing. The concentrations of the eight target elements (especially As and Cd) were especially high in the topsoil 100 m from the smelter and decreased markedly with increasing distance from the smelter and with increasing soil depth. Cadmium bio-concentration factors in the vegetables were the highest followed by Tl, Cu, Zn, In, Sb, Pb, and then As. The concentrations of As, Cd and Pb in vegetables were 86.7, 100 and 80.0 %, respectively, over the permissible limits and possible contamination by Tl may also be of concern. Changes in soil microbial counts and average well colour development were also significantly different at different sampling distances from the smelter. The degree of tolerance to heavy metals appears to be fungi > bacteria > actinomycetes. The 454 pyrosequencing indicates that long-term metal contamination from the smelting activities has resulted in shifts in the composition of the soil bacterial community.

This study is concerned with the removal performance of the antibiotic ciprofloxacin (CIP) from synthetic solutions by electrocoagulation (EC), as well as the toxic effects of treated CIP solutions. A response surface analysis (RSA) was applied to search optimal operational parameter values of the pH of solution, electrical current density (ECD), and electrolysis time (ET). The EC efficiency was evaluated by determining the total organic carbon (TOC) and CIP concentration performed by high-performance liquid chromatography. Although the best EC efficiency was attained at pH = 8, ECD = 22.2 A m⁻², and ET = 75 min, toxicity and antibacterial tests were performed using Artemia salina cysts and Staphylococcus aureus and Escherichia coli microorganisms in a wide ET range and other pH and ECD values. Increasing optimal pH value (9), along with reducing optimal ECD value (18 A m⁻²) and regarding low ET values, similar results for the removal of CIP (98%) and TOC (87%) were also attained. Toxicity variation was observed during EC process in synthetic solutions with the lowest antibacterial effects due to CIP and recalcitrant compound residues after 40 min of ET. These results clearly showed that the EC process presents a promising alternative method for the treatment of wastewaters containing high CIP concentrations.

This manuscript reports on a study of new biocatalysts for the biodegradation of pyrethroid pesticides, such as esfenvalerate. Experiments of esfenvalerate biodegradation by bacteria isolated from Brazilian savannah (Curtobacterium sp. CBMAI 1834, Bacillus sp. 2B, Lysinibacillus sp. CBMAI 1837, and Bacillus sp. 4T), sea (Kocuria sp. CBMAI 135, Kocuria sp. CBMAI 136, Kocuria marina CBMAI 141, and Kocuria sp. CBMAI 145), and a tropical peat usually known as “turfa” soil (Bacillus sp. P5CBNB, Kosakonia sp. CBMAI 1836, Bacillus sp. CBMAI 1833, and Kosakonia sp. CBMAI 1835) were performed. A biodegradation pathway was proposed for a better understanding of the environmental fate of the above mentioned insecticide. Esfenvalerate (S,S-fenvalerate) and its metabolites [3-phenoxybenzaldehyde (PBAld), 3-phenoxybenzoic acid (PBAc), 3-phenoxybenzyl alcohol, and 2-(4-chlorophenyl)-3-methylbutyric acid) (CLAc)] were quantitatively analyzed in triplicate experiments by a validated method. Initially, 100 mg L⁻¹ esfenvalerate (Sumidan 150SC) was added for each experiment. The residual esfenvalerate (104.7–41.6 mg L⁻¹) and formation of PBAc (0.1–8.1 mg L⁻¹), ClAc (1.5–11.0 mg L⁻¹), PBAlc (0.9 mg L⁻¹), and PBAld (completely biotransformed) were quantified. The 12 bacterial strains accelerated (with different efficiencies) the esfenvalerate degradation and increased the metabolites concentrations. A new and more complete biodegradation pathway based on HPLC-time of flight (ToF) and gas chromatography-mass spectrometry (GC-MS) analyses (in which thermal instability products were detected) was proposed. The detected metabolites are smaller and more polar compounds that may be carried by water and contaminate the environment.

Biomixtures comprise the active part of biopurification systems (BPS) for the removal of pesticide-containing wastewater from agricultural origin. Considering that biomixtures contain an important amount of lignocellulosic substrates, their bioaugmentation with degrading ligninolytic fungi represents a promising way to improve BPS. The fungus Trametes versicolor was employed for the bioaugmentation of rice husk-compost-soil (GCS) biomixtures in order to optimize the removal of the highly toxic insecticide/nematicide carbofuran (CFN). Composition of biomixtures has not been optimized before, and usually, a volumetric composition of 50:25:25 (lignocellulosic substrate:humic component:soil) is employed. Optimization of the biomixture composition was performed with a central composite design, using the volumetric content of rice husk (pre-colonized by the fungus) and the volumetric ratio compost/soil as design variables. Performance of biomixtures was comprehensively assayed considering CFN removal, the production of toxic transformation products (3-hydroxycarbofuran/3-ketocarbofuran), the ability to mineralize [¹⁴C]carbofuran, and the residual toxicity in the matrix. According to the models, the optimal volumetric composition of the GCS biomixture is 30:43:27, which maximizes removal and mineralization rate, and minimizes the accumulation of transformation products. Results support the value of assessing new biomixture formulations according to the target pesticide in order to obtain their optimal performance, before their use in BPS.

The use of synthetic dyes is commonplace in many industries, and the effluent is often dumped into the environment with no prior treatment. The aim of the present study was to analyze the use of an industrial strain of Saccharomyces cerevisiae (Meyen) for the removal of the textile dye Acid Blue 161 from an aqueous solution. Kinetic, isotherm, and thermodynamic models were created to evaluate the biosorption mechanisms. Fourier transfer infrared (FT-IR) spectroscopy was used to characterize and identify possible binding sites. A toxicity test was also performed using Artemia salina to analyze the degree of toxicity of the dye following treatment. The kinetic results demonstrated the occurrence of intraparticle diffusion in the yeast cells as the controlling mechanism of the sorption process. Biosorption followed the Langmuir model, except at pH 8.50, when it fit the Freundlich model. The thermodynamic results demonstrate that the biosorption process is spontaneous and endothermic. The FT-IR analyses confirmed the occurrence of a chemical reaction in acid pH, but physical adsorption only occurred at pH 8.50. The toxicity test showed that the use of the yeast biomass led to the complete removal of toxicity from the dye solution, demonstrating the effectiveness of the biosorption process in the treatment of effluents contaminated with these compounds.

We investigated the horizontal and vertical distribution of heavy metals (Hg, Pb, Zn, Cu, Cd, As, Ni, and Cr) in soils in the water source protection zone for Shanghai to study the origins of these metals, their connections with urbanization, and their potential risk posed on the ecosystem. Determination of metal concentrations in 50 topsoil samples and nine soil profiles indicated that Hg, Pb, Zn, and Cu were present in significantly higher concentrations in topsoil than in deep soil layers. The spatial distributions of Hg, Pb, Zn, and Cu and contamination hotspots for these metals in the study area were similar to those near heavy industries and urban built-up areas. Emissions from automobiles resulted in increased soil concentrations of Cu, Pb, and Zn along roadsides, while high concentrations of Hg in the soil resulted from recent atmospheric deposition. Calculation of the potential ecological risk indicated that the integrative risk of these heavy metals in most areas was low, but a few sites surrounding high density of factories showed moderate risks.

Biodegradable polymer poly(3-hydroxybutyrate) (P3HB) has been used as a matrix to construct slow-release formulations of the fungicide tebuconazole (TEB). P3HB/TEB systems constructed as films and pellets have been studied using differential scanning calorimetry, X-ray structure analysis, and Fourier transform infrared spectroscopy. TEB release from the experimental formulations has been studied in aqueous and soil laboratory systems. In the soil with known composition of microbial community, polymer was degraded, and TEB release after 35 days reached 60 and 36 % from films and pellets, respectively. That was 1.23 and 1.8 times more than the amount released to the water after 60 days in a sterile aqueous system. Incubation of P3HB/TEB films and pellets in the soil stimulated development of P3HB-degrading microorganisms of the genera Pseudomonas, Stenotrophomonas, Variovorax, and Streptomyces. Experiments with phytopathogenic fungi F. moniliforme and F. solani showed that the experimental P3HB/TEB formulations had antifungal activity comparable with that of free TEB.

In recent years, high concentrations of hexavalent chromium, Cr(VI), have been observed in the groundwater system of the Asopos River Basin, raising public concern regarding the quality of drinking and irrigation water. The work described herein focuses on the development of a groundwater flow and Cr(VI) transport model using hydrologic, geologic, and water quality data collected from various sources. An important dataset for this goal comprised an extensive time series of Cr(VI) concentrations at various locations that provided an indication of areas of high concentration and also served as model calibration locations. Two main sources of Cr(VI) contamination were considered in the area: anthropogenic contamination originating from Cr-rich industrial wastes buried or injected into the aquifer and geogenic contamination from the leaching process of ophiolitic rocks. The aquifer’s response under climatic change scenario A2 was also investigated for the next two decades. Under this scenario, it is expected that rainfall, and thus infiltration, will decrease by 7.7 % during the winter and 15 % during the summer periods. The results for two sub-scenarios (linear and variable precipitation reduction) that were implemented based on A2 show that the impact on the study aquifer is moderate, resulting in a mean level decrease less than 1 m in both cases. The drier climatic conditions resulted in higher Cr(VI) concentrations, especially around the industrial areas.

Medium-pressure (MP) ultra violet (UV) disinfection was suggested as a pre-treatment to control biofouling in a semi-scale flow-through model water system. Water, spiked with Pseudomonas aeruginosa, nutrients, and carbon source, was flowed through the system and biofilm formation on glass, PVC, and stainless steel 316 slides was examined following 24 h runs. Following UV exposure a ∼99 % reduction in biovolume and average thickness of the biofilm was observed on all surfaces examined, despite clear differences in the virgin surface characteristics analyzed using contact angle, zeta potential, and atomic force microscopy (AFM). The findings support the stochastic behavior of biological systems in relation to predictions derived from conventional theories. The reduction of viable microbial counts seems to be the major mechanism in reducing the actual biofilm formation rate and the overall effect UV provides could indeed render it an effective tool in mitigating biofilm formation in water distribution systems.