Safety assessment and designing of safer ionic liquids (ILs) are among the priorities of the chemists and toxicologists today. Computational approaches have been considered as appropriate methods for prior safety assessment of chemicals and tools to aid in structural designing. The present study is an attempt to investigate the chemical attributes of a wide variety of ILs towards their cytotoxicity in leukemia rat cell line IPC-81 through the development of nonlinear quantitative structure-activity relationship (QSAR) models in the light of the OECD principles for QSAR development. Here, the cascade correlation network (CCN), probabilistic neural network (PNN), and generalized regression neural networks (GRNN) QSAR models were established for the discrimination of ILs in four categories of cytotoxicity and their end-point prediction using few simple descriptors. The diversity and nonlinearity of the considered dataset were evaluated through computing the Euclidean distance and Brock-Dechert-Scheinkman statistics. The constructed QSAR models were validated with external test data. The predictive power of these models was established through a variety of stringent parameters recommended in QSAR literature. The classification QSARs rendered the accuracy of >86 %, and the regression models yielded correlation (R ²) of >0.90 in test data. The developed QSAR models exhibited high statistical confidence and identified the structural elements of the ILs responsible for their cytotoxicity and, hence, could be useful tools in structural designing of safer and green ILs.

Nanoparticles (NPs) are an increasingly common contaminant in agro-environments, and their potential effect on genetically modified (GM) crops has been largely unexplored. GM crop exposure to NPs is likely to increase as both technologies develop. To better understand the implications of nanoparticles on GM plants in agriculture, we performed a glasshouse study to quantify the uptake of Fe₂O₃ NPs on transgenic and non-transgenic rice plants. We measured nutrient concentrations, biomass, enzyme activity, and the concentration of two phytohormones, abscisic acid (ABA) and indole-3-acetic acid (IAA), and malondialdehyde (MDA). Root phytohormone inhibition was positively correlated with Fe₂O₃ NP concentrations, indicating that Fe₂O₃ had a significant influence on the production of these hormones. The activities of antioxidant enzymes were significantly higher as a factor of low Fe₂O₃ NP treatment concentration and significantly lower at high NP concentrations, but only among transgenic plants. There was also a positive correlation between the treatment concentration of Fe₂O₃ and iron accumulation, and the magnitude of this effect was greatest among non-transgenic plants. The differences in root phytohormone production and antioxidant enzyme activity between transgenic and non-transgenic rice plants in vivo suggests that GM crops may react to NP exposure differently than conventional crops. It is the first study of NPs that may have an impact on GM crops, and a realistic significance for food security and food safety.

The gametogenic cycle of the Cerastoderma glaucum was analyzed using both qualitative and semi-quantitative methods. The condition index and glycogen concentrations were determined in order to provide information on energy storage. The cockles were collected monthly from a Bayyadha site located 15 km south of Sfax City (Gulf of Gabès) between January 2007 and January 2008. From histological point of view, we applied two approaches: (i) the qualitative method describing the various stages of gamete development for males and females during a cycle of 13 months, and (ii) the semi-quantitative method concerning the estimation of different tissue surfaces. The results showed that there is evidence of three periods of reproduction in this population. A comparison between the surfaces occupied by the three organs showed that the foot and the gonad surfaces are higher than the surface of the adductor muscle. This could suggest that these two organs are more involved in the process of glycogen reserve storage. The results of the glycogen concentrations in the different tissues (gonad, adductor muscle, and “remainders”) show that during the second and third periods of reproduction, glycogen was stored in the adductor muscle and in the remainder during sexual rest, and in the gonad during the gametogenesis phases in order to supply the reproductive effort. On the contrary, in the first period of reproduction, the low concentrations of glycogen recorded in the gonad coincided with its high degree of development. This fact could be related to environmental conditions (low temperature and food) recorded during this period.

Geographically based investigations into atmospheric bio-monitoring usually provide information on concentration or occurrence data and spatial trends of specific contaminants over a specified study area. In this work, an original approach based on geographic information system (GIS) was used to establish metal contents (Hg, Cu, Pb, and Cd) in epiphytic lichens from 90 locations as atmospheric bio-monitors over a meso-scale area (Pyrénées-Atlantiques, southwestern France). This approach allows the integration of the heterogeneity of the territory and optimization of the sampling sites based on both socioeconomical and geophysical parameters (hereafter defined as urban, industrial, agricultural, and forested areas). The sampling strategy was first evaluated in several sites (n = 15) over different seasons and years in order to follow the temporal variability of the atmospheric metal input in lichens. The results demonstrate that concentration ranges remain constant over different sampling periods in “rural” areas (agricultural and forested). Higher variability is observed in the “anthropized” urban and industrial areas in relation to local atmospheric inputs. In this context, metal concentrations in lichens over the whole study show that (1) Hg and Cd are homogeneous over the whole territory (0.14 ± 0.04 and 0.38 ± 0.26 mg/kg, respectively), whereas (2) Cu and Pb are more concentrated in “anthropized” areas (9.3 and 11.9 mg/kg, respectively) than in “rural” ones (6.8 and 6.0 mg/kg, respectively) (Kruskall-Wallis, K(Cu) = 13.7 and K(Pb) = 9.7, p < 0.00001). They also showed a significant local enrichment for all metals in many locations in the Pays Basque (West) mainly due to metal and steel industrial activities. This confirms the local contribution of this contamination source over a wider geographic scale. A multiple linear regression model was applied to give an integrated spatialization of the data. This showed significant relationships for Pb and Cu (adjusted r ² of 0.39 and 0.45, respectively), especially with regards to variables such as industry and road densities (source factors) and elevation or water balance (remote factors). These results show that an integrated GIS-based sampling strategy can improve biomonitoring data distribution and allows better differentiation of local and long-range contamination.

Duckweed has shown great potential for both energy and environmental applications, particularly in wastewater treatment and fuel ethanol production. A rhizobacterium, Exiguobacterium sp. MH3, has been reported to associate with the duckweed Lemna minor for symbiotic growth. The aim of this work is to study the effects of rhizobacterium MH3 on L. minor growth and chromium (Cr) remediation. It appeared to have a synergism between the rhizobacterium MH3 and duckweed; the presence of strain MH3 promoted the growth of duckweeds by increasing both the frond number and dry weight of duckweed by more than 30 %, while duckweed in turn provided essential carbon source and energy for the growth of rhizobacterium MH3. Under Cr(VI) exposure, particularly at higher Cr(VI) concentrations, Exiguobacterium sp. MH3 significantly alleviated the harmful effects of the stress on the duckweed by promoting duckweed growth and preventing duckweed from excessive uptake of Cr. Potential mechanisms were also discussed in light of the genome sequence of strain MH3, and it was speculated that siderophores and indole-3-acetic acid (IAA) secreted by strain MH3 might contribute to promoting duckweed growth.

Cadmium (Cd) is an important toxic chemical due to its increasing levels in the environment and its resulting accumulation in humans and animals. The present study was performed to evaluate the long-term effects of low doses of Cd administered in offspring by oral route to rats during pregnancy and lactation. There were no adverse effects on the physical and sexual development in the pups, except to delay the development of offspring. The relative weights of livers and kidneys in the adult female offspring were significantly decreased after exposure to 10 ppm Cd. These results indicated that there were adverse effects on growth and development from exposure to 5 or 10 ppm Cd in utero and during lactation. The results also showed differential gender sensitivity effects on the organ weights.

This study aims to understand the mechanisms of nitrite appearance during wastewater denitrification by biofilters, focusing on the role of the carbon source. Experiments were carried out at lab-scale (batch tests) and full-scale plant (Parisian plant, capacities of 240,000 m³ day⁻¹). Results showed that the nature of the carbon source affects nitrite accumulation rates. This accumulation is low, 0.05 to 0.10 g N-NO₂ ⁻ per g N-NO₃ ⁻ eliminated, for alcohols such as methanol, ethanol, or glycerol. The utilization of glycerol leads to fungal development causing clogging of the biofilters. This fungal growth and consequent clogging exclude this carbon source, with little nitrite accumulation, as carbon source for denitrification. Whatever the carbon source, the C/N ratio in the biofilter plays a major role in the appearance of residual nitrite; an optimal C/N ratio from 3.0 to 3.2 allows a complete denitrification without any nitrite accumulation.

Microbial community compositions in pesticide-contaminated aquifers have not been studied, although such information is important for remediation and maintaining freshwater sources clean under changing climate. Therefore, phospholipid (PLFAs), glycolipid (GLFAs), and neutral lipid (NLFAs) fatty acids were determined from sand and clay sediments at depths of 0.3–24.8 m, all contaminated with triazines and dichlobenil/2,6-dichlorobenzamide. The portion of fungi and Gram-negative bacteria at 0.3 m was greater than at 0.8 m, where the percentage of Gram-positive bacteria, actinobacteria, and sulfate-reducing bacteria (SRB) increased. In deeper sediments, microbial biomass, activity, and diversity decreased. Clay sediments seemed to serve as a reservoir for slow pesticide elution to groundwater, and their biomarker portion for all bacteria except actinobacteria was greater than in sand sediments. The slow pesticide dissipation seemed to occur in the main groundwater flow zone, resulting in nitrogen release simultaneously with organic matter elution from gardening and bank filtration. As a result, microbial biomass, activity, and diversity were increased. This shift in conditions towards that in surface soil may be appropriate for enhanced natural attenuation of pesticides in groundwater sources.

Selected pharmaceuticals including antibiotics, antipyretics, a stimulant, an antiepileptic and an antipsychotic drug were determined in wastewater, surface water and sediment along the Umgeni River which is the main source of water to Durban City in KwaZulu-Natal, South Africa. Samples were analysed using high-performance liquid chromatography coupled to a mass spectrometer (HPLC-MS/MS) after clean up and pre-concentration by solid phase extraction (SPE). At the wastewater treatment plant outlet, the antipyretic ibuprofen was detected in concentrations up to 12.94 μg/L and 15.96 ng/g in wastewater and bio-solids, respectively. The antipsychotic clozapine was detected in concentrations up to 14.43 μg/L and 18.75 ng/g in wastewater and bio-solids, respectively. Other pharmaceuticals namely sulfamethazine, sulfamethoxazole, erythromycin, metronidazole, trimethoprim, acetaminophen, caffeine and carbamazepine were also detected but in lower concentration compared to clozapine and ibuprofen (<10 μg/L or 10 ng/g). Clozapine and ibuprofen were detected at high concentrations in the surface water and sediment of Umgeni River. The highest concentration of clozapine (78.33 μg/L) was detected at the business park, while that for ibuprofen (62.0 μg/L) was detected at the point where a tributary, Msunduzi, joins Umgeni. Metronidazole was only detected in sediment, and caffeine (2243.52 ng/g) was detected at the highest concentration in the sediment at the blue lagoon sampling site. The antibiotic sulfamethoxazole was also detected in appreciable amounts up to 507.34 ng/g in the sediment at the Msunduzi tributary sampling site. The data collected implies that while insufficiently treated wastewater contributes to surface water contamination, human activities also contribute appreciably to the pharmaceutical loading of River Umgeni.

The oxidation of diclofenac (DCF), a non-steroidal anti-inflammatory drug and emerging water pollutant, with chlorine dioxide was investigated under simulated water disinfection conditions. The reaction kinetics as functions of the initial concentrations of DCF, different nitrogenous species, and different pE values were experimentally determined. The results demonstrated that DCF reacted rapidly with ClO₂, where more than 75 % of DCF (≤3.00 μM) was removed by 18.94 μM ClO₂ within 60 s. All of the reactions followed pseudo first-order kinetics with respect to DCF, and the rate constant, k ₒbₛ, exhibited a significant decrease from 4.21 × 10⁻² to 8.09 × 10⁻³ s⁻¹, as the initial DCF concentration was increased from 1.00 to 5.00 μM. Furthermore, the degradation kinetics of DCF was clearly dependent on nitrogen-containing ion concentrations in the reaction solution. Ammonium and nitrite ions inhibited the DCF degradation by ClO₂, whereas nitrate ion clearly initiated its promotion. In contrast, the inhibitory effect of NO₂ ⁻ was more robust than that of NH₄ ⁺. When the values of pE were gradually increased, the transformation of NH₄ ⁺ to NO₂ ⁻, and subsequently to NO₃ ⁻, would occur, the rate constants were initially decreased, and then increased. When NH₄ ⁺ and NO₂ ⁻ coexisted, the inhibitory effect on the DCF degradation was less than the sum of the partial inhibitory effect. However, when NO₂ ⁻ and NO₃ ⁻ coexisted, the actual inhibition rate was greater than the theoretical estimate. These results indicated that the interaction of NH₄ ⁺ and NO₂ ⁻ was antagonistic, while the coexistence of NO₂ ⁻ and NO₃ ⁻ was observed to have a synergistic effect in aqueous environments.