Applications based on silver nanoparticles (AgNPs) are limited by low temperatures, which cause aggregation of the nanoparticle fraction, leading to reduced efficacy of their products. We aimed at studying AgNP synthesis by psychrotolerant bacteria, its stability under long-term storage, and larvicidal activity under low-temperature conditions. Electron and atomic force microscopy studies revealed that 6 among 22 psychrotolerant isolates synthesized AgNPs with an average diameter of 1.9–14.1 nm. Pseudomonas mandelii SR1 synthesized the least-sized AgNPs with an average diameter of 1.9–10 nm, at temperatures as low as 12 °C without aggregate formation, and the synthesized nanoparticles were stable for up to 19 months of storage period. On studying their larvicidal activity, LC₉₀(lethal concentration) values against Anopheles subpictus and Culex tritaeniorhynchus larvae were at 31.7 and 35.6 mg/L, respectively. Stable non-aggregate AgNPs at low-temperature conditions from P. mandelii SR1, coupled with their larvicidal property, can be applied to control larval populations in water bodies located in seasonal or permanently cold environments.

Accurate knowledge about factors and conditions determining copper (Cu) toxicity in soil is needed for predicting plant growth in various Cu-contaminated soils. Therefore, effects of Cu on growth (biomass production) of lettuce (Lactuca sativa) were tested on seven selected, very different soils spiked with Cu and aged for 2 months at 35 °C. Cu toxicity was expressed as pEC₅₀(Cu²⁺), i.e., the negative logarithm of the EC₅₀(Cu²⁺) activity to plant growth. The determined pEC₅₀(Cu²⁺) was significantly and positively correlated with both the analytically readily available soil pH and concentration of dissolved organic carbon [DOC] which together could explain 87 % of the pEC₅₀(Cu²⁺) variation according to the simple equation: pEC₅₀(Cu²⁺) = 0.98 × pH + 345 × [DOC] − 0.27. Other soil characteristics, including the base cation concentrations (Na⁺, K⁺, Ca²⁺, Mg²⁺), the cation exchange capacity at soil pH (ECEC), and at pH 7 (CEC₇), soil organic carbon, clay content, and electric conductivity as well as the distribution coefficient (Kd) calculated as the ratio between total soil Cu and water-extractable Cu did not correlate significantly with pEC₅₀(Cu²⁺). Consequently, Cu toxicity, expressed as the negative log of the Cu²⁺activity, to plant growth increases at increasing pH and DOC, which needs to be considered in future management of plant growth on Cu-contaminated soils. The developed regression equation allows identification of soil types in which the phytotoxicity potential of Cu is highest.

Several studies have reported that the chewing habit of smokeless tobacco (SLT) has been associated with oral cancer. The aim of the present study was to evaluate the trace levels of lead (Pb) in biological samples (blood, scalp hair) of oral cancer patients and referents of the same age group (range 30–60 years). As the concentrations of Pb are very low in biological samples, so a simple and efficient ionic liquid-based microextraction in a single syringe system has been developed, as a prior step to determination by flame atomic absorption spectrometry. In this procedure, the hydrophobic chelates of Pb with ammonium pyrrolidinedithiocarbamate (APDC) were extracted into fine droplets of 1-butyl-3-methylimidazolium hexafluorophosphate [C₄MIM][PF₆] within a syringe while using Triton X-114 as a dispersant. Factors influencing the microextraction efficiency and determination, such as pH of the sample, volume of [C₄MIM][PF₆] and Triton X-114, ligand concentration, and incubation time, were studied. To validate the proposed method, certified reference materials were analyzed and the results of Pb²⁺ were in good agreement with certified values. At optimum experimental values of significant variables, detection limit and enhancement factor were found to be 0.412 μg/L and 80, respectively. The coexisting ions showed no obvious negative outcome on Pb preconcentration. The proposed method was applied satisfactorily for the preconcentration of Pb²⁺ in acid-digested SLT and biological samples of the study population. It was observed that oral cancer patients who consumed different SLT products have 2–3-fold higher levels of Pb in scalp hair and blood samples as compared to healthy referents (p < 0.001). While 31.4–50.8 % higher levels of Pb were observed in referents chewing different SLT products as compared to nonconsumers (p < 0.01).

There is scarcity in literature in regards to the exact levels of such compounds in the Middle Eastern region including Jordan. This study was conducted to measure the presence and levels of perfluoroalkyl substances (PFASs) (perfluoroocane sulfonate (PFOS) and perfluorooctanoic acid (PFOA)) in human milk and local fresh cow milk in northern Jordan and also to investigate the relationship between levels of PFASs and some sociodemographic characteristics of breastfeeding mothers and their infants as well as usage of Teflon kitchenware products. Seventy-nine milk samples were collected from breastfeeding women and 25 samples from local fresh cow milk in northern Jordan. Levels of PFOS and PFOA were liquid/liquid extracted (LLE) by acetone followed by purification on an Oasis hydrophilic-lipophilic balance (HLB) solid-phase extraction (SPE). Separations and detections were performed by liquid chromatography-tandem mass spectrometry. Limits of quantitation (LOQs) were 10 ng/L for both PFOA and PFOS. The measured concentrations ranged between non-detectable (ND) and 178 ng/L for PFOS and between 24 and 1120 ng/L for PFOA in human milk and between ND-178 ng/L and LOQ-160 ng/L in fresh cow milk, respectively. Median concentrations of PFOS in human milk samples from Jordan in this study were lower than those found in a recent study from Italy. Moreover, mean concentrations of PFOA and PFOS were significantly higher in milk samples provided by older women. Also, mean concentrations of PFOA was much higher in multiparas and those who have younger infants. The mean rank of PFOA was twice as high in the milk of women who had older Teflon products in kitchen compared to those who had relatively new Teflon products.

Mechanisms of Pteris vittata L. to hyperaccumulate arsenic (As), especially the efficient translocation of As from rhizoids to fronds, are not clear yet. The present study aims to investigate the role of transpiration in the accumulation of As from the aspects of transpiration regulation and ecotypic difference. Results showed that As accumulation of P. vittata increased proportionally with an increase in the As exposure concentration. Lowering the transpiration rate by 28∼67 % decreased the shoot As concentration by 19∼56 %. Comparison of As distribution under normal treatment and shade treatment indicated that transpiration determines the distribution pattern of As in pinnae. In terms of the ecotypic difference, the P. vittata ecotype from moister and warmer habitat had 40 % higher transpiration and correspondingly 40 % higher shoot As concentration than the ecotype from drier and cooler habitat. Results disclosed that transpiration is the main driver for P. vittata to accumulate and re-distribute As in pinnae.

Textile industry is considered as one of the important factors of the economic growth in Tunisia. However, this prominent role has certainly some drawbacks mainly represented by the huge amounts of textile wastewaters generated that become a real menace to nature. Many previous studies showed the purifying potential of some activated sludge and bacteria (Pseudomonas putida) to decolourize textile effluents. However, in many cases, decolourization of wastewaters is not necessary associated with detoxification, generating a real risk for the ecosystem in general. We evaluated in this work the induced toxicity of a textile effluent before and after its treatment with activated sludge followed by P. putida, using a battery of biotests. This study proved the detoxifying power of the activated sludge according to most of ecotoxicity tests. The treatment with P. putida did not improve the quality of the effluent; on the contrary, it could increase its toxicity. Daphnia magna and Raphidocelis subcapitata appear to be the most sensitive organisms in assessing eventual toxicity caused by this kind of wastewaters.

Wet Oxidation (WO) of sewage sludge is a chemical oxidation of sludge at high temperatures and pressures by means of an oxygen-containing gas. The liquid stream originated by WO is easily biodegradable, and therefore, the recirculation to the biological Waste Water Treatment Plant (WWTP) may be a feasible solution. However, the WO effluent has a residual organic and nitrogen content so that its treatment may be required when the receiving WWTP has no surplus treatment capacity left. The aim of this research was the assessment of the anaerobic treatability of the WO liquid residue, in order to reduce the organic load to be recirculated to the WWTP, simultaneously promoting energy recovery. For this purpose, the liquid residue obtained during full scale WO tests on two different types of sludge was submitted to anaerobic digestion in a continuous flow pilot reactor (V = 5 L). Furthermore, batch tests were carried out in order to evaluate possible inhibition factors. Experimental results showed that, after the start-up/acclimation period (~130 days), Chemical Oxygen Demand (COD) removal efficiency was stably around 60 % for about 120 days, despite the change in operating conditions. In the last phase of the experimental activity, COD removal reached 70 % under the following treatment conditions: Hydraulic Retention Time (HRT) = 20 days, Volumetric Organic Loading Rate (VOLR) = 0.868 kg COD/m³/day, Organic Loading Rate per Volatile Suspended Solids (OLRᵥₛₛ) = 0.078 kg COD/kg VSS/day, temperature (T) = 36.5 °C, pH = 8. Energy balance calculation demonstrated anaerobic treatment sustainability.

Today, several technologies and management strategies are proposed and applied in wastewater treatment plants (WWTPs) to minimise sludge production and contamination. In order to avoid a shifting of burdens between different areas, their techno-economic and environmental performance has to be carefully evaluated. Wet oxidation (WO) is an alternative solution to incineration for recovering energy in sewage sludge while converting it to mostly inorganic residues. This paper deals with an experimentation carried out within the EU project “ROUTES”. A mass balance was made for a WWTP (500,000 person equivalents) in which a WO stage for sludge minimisation was considered to be installed. Both bench- and full-scale test results were used. Design of treatment units and estimation of capital and operational costs were then performed. Subsequently, technical and economic aspects were evaluated by means of a detailed methodology which was developed within the ROUTES project. Finally, an assessment of environmental impacts from a life cycle perspective was performed. The integrated assessment showed that for the specific upgrade considered in this study, WO technology, although requiring a certain increase of technical complexity at the WWTP, may contribute to environmental and economic advantages. The paper provides guidance in terms of which aspects need a more thorough evaluation in relation to the specific case in which an upgrade with WO is considered.

We have created a divided convective-dispersive transport (D-CDT) model that can be used to provide an accurate simulation of conservative transport processes in planted horizontal sub-surface flow constructed wetlands filled with coarse gravel (HSFCW-C). This model makes a fitted response curve from the sum of two independent CDT curves, which show the contributions of the main and side streams. The analytical solutions of both CDT curves are inverse Gaussian distribution functions. We used Fréchet distribution to provide a fast optimization mathematical procedure. As a result of our detailed analysis, we concluded that the most important role in the fast upward part of the tracer response curve is played by the main stream, with high porous velocity and dispersion. This gives the first inverse Gaussian distribution function. The side stream shows slower transport processes in the micro-porous system, and this shows the impact of back-mixing and dead zones, too. The significance of this new model is that it can simulate transport processes in this kind of systems more accurately than the conventionally used convective-dispersive transport (CDT) model. The calculated velocity and dispersion coefficients with the D-CDT model gave differences of 24–54 % (of velocity) and 22–308 % (of dispersion coeff.) from the conventional CDT model, and were closer to actual hydraulic behaviour.

This study assessed the responses of molecular biomarkers and heavy metal levels in Cerastoderma glaucum exposed for 1 week to two industrial effluents (1 %) discharged into the Tunisian coastal area, F₁ and F₂, produced by different units of production of a phosphate treatment plant. A significant uptake of metals (Cd, Cu, Zn, and Ni) was observed in exposed cockles compared to controls, with an uptake higher for F₁ than for F₂. A decrease in LT50 (stress on stress test) was also observed after an exposure to the effluent F₁. Treatments resulted in different patterns of messenger RNA (mRNA) expression of the different genes tested in this report. Gene transcription monitoring performed on seven genes potentially involved in the tolerance to metal exposure showed that for both exposures, mechanisms are rapidly and synchronically settled down to prevent damage to cellular components, by (1) handling and exporting out metal ions through the up-regulation of ATP-binding cassette xenobiotic transporter (ABCB1) and metallothionein (MT), (2) increasing the mRNA expression of antioxidant enzymes (catalase (CAT), superoxide dismutases, CuZnSOD and MnSOD), (3) protecting and/or repairing proteins through the expression of heat shock protein 70 (HSP70) mRNAs, and (4) increasing ATP production (through the up-regulation of cytochrome c oxidase 1 (CO1)) to provide energy for cells to tolerate stress exposure. The tools developed may be useful both for future control strategies and for the use of the cockle C. glaucum as a sentinel species.