The aim of this study was to investigate heavy metals and selected minerals contents in filets of pikeperch (Sander lucioperca), carp (Cyprinus carpio) and flathead grey mullet (Mugil cephalus), the major fish species produced in Sidi-Salem reservoir; the largest Tunisian freshwater ecosystem. Concentrations of Ca, Mg, Fe, Zn, Cd, Pb and Hg were determined by inductively coupled plasma-optical emission spectrometry, while concentrations of Na and P were determined by flame photometry and spectrophotometry, respectively. Results concerning heavy metals are considered quantitatively reliable for Hg and Cd but must be taken with precautions concerning Pb levels as the LOD (limit of detection) of the analytical process was higher than acceptable limit. They showed greater accumulations of both Hg and Cd in filets of pikeperch than in filets of carp and mullet, but none of the values exceeded the normative maximum levels (0.500 and 0.050 mg kg⁻¹ w.w., respectively). Considering provisional intakes, target hazard quotient and hazard index, estimated for a fish portion per week, consumption of any of the species did not appear to be potentially hazardous for the health as they were far below threshold values. A fish portion would provide substantial amounts (>15% of daily requirements) in essential mineral nutrients (P, Mg and Fe) and thus should be considered an interesting contribution to a healthy diet. It is strongly advocated to authorities including freshwater fish in the official national annual control survey of contaminants in fishery products, which in addition to guaranteeing security of consumers, would also allow diversifying valorisation opportunities and thus increase the economic value of this fish production.

Recent studies have shown that direct interspecies electron transfer (DIET) plays an important part in contributing to methane production from anaerobic digestion. However, so far anaerobic digestion models that have been proposed only consider two pathways for methane production, namely, acetoclastic methanogenesis and hydrogenotrophic methanogenesis, via indirect interspecies hydrogen transfer, which lacks an effective way for incorporating DIET into this paradigm. In this work, a new mathematical model is specifically developed to describe DIET process in anaerobic digestion through introducing extracellular electron transfer as a new pathway for methane production, taking anaerobic transformation of ethanol to methane as an example. The developed model was able to successfully predict experimental data on methane dynamics under different experimental conditions, supporting the validity of the developed model. Modeling predictions clearly demonstrated that DIET plays an important role in contributing to overall methane production (up to 33 %) and conductive material (i.e., carbon cloth) addition would significantly promote DIET through increasing ethanol conversion rate and methane production rate. The model developed in this work will potentially enhance our current understanding on syntrophic metabolism via DIET.

Leaf microbial communities possess a large panel of enzymes permitting the breakdown of leaf polymers as well as the transformation of organic xenobiotic compounds present in stream waters. This study aims to assess the potential of leaf microbial communities, exhibiting different exposure histories to pesticides (upstream versus downstream), to biotransform three maize herbicides (mesotrione, S-metolachlor, and nicosulfuron) in single and cocktail molecule exposures. The results showed a high dissipation of nicosulfuron (sulfonylurea herbicide) (from 29.1 ± 10.8% to 66 ± 16.2%, day 40) in both single and cocktail exposures, respectively, but not of mesotrione and S-metolachlor. The formation of nicosulfuron metabolites such as ASDM (2-(aminosulfonyl)-N,N-dimethyl-3-pyridinecarboxamide) and ADMP (2-amino-4,6-dimethoxypyrimidine) and the weak sorption (<0.4%) on the leaf matrix confirmed the transformation of this molecule by leaf microorganisms. In addition, the downstream communities showed a greater ability to transform nicosulfuron than the upstream communities suggesting that the exposure history to pesticides is an important parameter and can enhance the biotransformation potential of leaf microorganisms. After 40-day single exposure to nicosulfuron, the downstream communities were also those experiencing the greatest shifts in fungal and bacterial community diversity suggesting a potential adaptation of microorganisms to this herbicide. Our study emphasizes the importance of leaf microbial communities for herbicide biotransformation in polluted stream ecosystems where fungi could play a crucial role.

Arbuscular mycorrhizal (AM) fungi have been used to alleviate heavy metal stress on plant growth and uptake of micro- and macroelements. A greenhouse pot experiment was conducted to verify the effects of AM fungus Rhizophagus irregularis on the growth, physiological characteristics, total Cd, and element uptake of Phragmites australis under different Cd stress (in the range of 0–20 mg L⁻¹). The results showed that the symbiosis could effectively alleviate Cd toxicity with greater root biomass, higher photosynthesis rate, and lower levels of malonaldehyde (MDA) and proline than non-mycorrhizal plants could. However, reduced transpiration rate (Tr) and stomatal conductance (g ₛ) indicated R. irregularis protected host plants from Cd stress (≥5 mg L⁻¹) via the stomatal closure. Although micro- and macroelements displayed differently in the presence of Cd, higher concentrations were still detected in mycorrhizal plants in contrast to non-mycorrhizal plants. Moreover, step multiple regression significantly demonstrated Pnₘₐₓ, stem diameter (Sd), and g ₛ were the important factors with regard to total Cd uptake in the symbiosis, but Mn affected to non-mycorrhizal plants. These results suggested R. irregularis could alleviate the competition between Mn and Cd by altering plant physiology. This work clearly demonstrated that R. irregularis can be able to support P. australis growth better even though under high Cd stress (>1 mg L⁻¹), suggesting its good potential for practical use in high Cd-contaminated areas.

With the aim of upgrading current food waste (FW) management strategy, a novel FW hydrothermal pretreatment and air-drying incineration system is proposed and optimized from an energy and exergy perspective. Parameters considered include the extracted steam quality, the final moisture content of dehydrated FW, and the reactor thermal efficiency. Results show that optimal working condition can be obtained when the temperature and pressure of extracted steam are 159 °C and 0.17 MPa, the final moisture content of dehydrated FW is 10%, and the reactor thermal efficiency is 90%. Under such circumstance, the optimal steam energy and exergy increments reach 194.92 and 324.50 kJ/kg-FW, respectively. The novel system is then applied under the local conditions of Hangzhou, China. Results show that approximately 2.7 or 11.6% (from energy or exergy analysis perspective) of electricity can be additionally generated from 1 ton of MSW if the proposed novel FW system is implemented. Besides, comparisons between energy and exergy analysis are also discussed.

The present study determines the influence of three ionic liquids (ILs) containing cations with diversified structure on the growth and development of spring barley seedlings and common radish leaves. Increasing amounts of 1-butyl-1-methylpyrrolidinium hexafluorophosphate [Pyrrol][PF₆], 1-butyl-1-methylpiperidinium hexafluorophosphate [Piper][PF₆], and 1-butyl-4-methylpyridinium hexafluorophosphate [Pyrid][PF₆] were added to the soil on which both plants were cultivated. The results of this studies showed that the applied ILs were highly toxic for plants, demonstrated by the inhibition of length of plant shoots and roots, decrease of fresh mass, and increase of dry weight content. Common radish turned out to be the plant with higher resistance to the used ILs. The differences in the cation structure did not influence phytotoxity of ILs for spring barley. Furthermore, all ILs led to a decrease of photosynthetic pigments, which was directly followed by decreased primary production in plants. Oxidative stress in plants occurred due to the presence of ILs in the soil, which was demonstrated by the increase of malondialdehyde (MDA) content, changes in the H₂O₂ level, and antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). The changes in the chlorophyll contents and the increase of POD activity turned out to be the most significant oxidative stress biomarkers in spring barley and common radish. Both spring barley and radish exposed to ILs accumulated a large amount of fluoride ion.

The relation between test conditions such as medium composition or pH on silver nanoparticle (AgNP) behavior and its link to toxicity is one of the major topics in nanoecotoxicological research in the last years. In addition, the adaptation of the ecotoxicological standard tests for nanomaterials is intensely discussed to increase comparability and reliability of results. Due to the limitation of test material production volumes and the need for high-throughput screening, miniaturization has been proposed for several test designs. In the present study, the effect of a miniaturization of the acute Daphnia immobilization test on AgNP behavior was investigated. For this purpose, available, adsorbed, and dissolved silver fractions were measured using AgNP and silver nitrate in the following two test designs: a standard test (ST) design and a miniaturized test (MT) design with reduced test volume and less animals. Despite the increase in surface area in relation to the test volume in MT, more AgNP attached to the ST vessel surface, so that in this case, exposure concentrations were significantly lower compared to the MT assessment. Ionic silver concentrations resulting from AgNP dissolution were similar in both test designs. The same was observed for ionic silver concentrations in silver nitrate (AgNO₃) treatments, but adsorbed silver was also higher in ST treatments. Assessing the structure-activity relationships revealed that surface properties such as hydrophobicity, potential binding sites, or surface roughness were of higher importance than surface:volume ratios for both test substances.

Following the Deepwater Horizon (DWH) event in 2010 subsurface hydrocarbon intrusions (1000–1300 m) and an order of magnitude increase in flocculent hydrocarbon deposition caused increased concentrations of hydrocarbons in continental slope sediments. This study sought to characterize the variability [density, Fisher’s alpha (S), equitability (E), Shannon (H)] of benthic foraminifera following the DWH event. A series of sediment cores were collected at two sites in the northeastern Gulf of Mexico from 2010 to 2012. At each site, three cores were utilized for benthic faunal analysis, organic geochemistry, and redox metal chemistry, respectively. The surface intervals (∼0–10 mm) of the sedimentary records collected in December 2010 at DSH08 and February 2011 at PCB06 were characterized by significant decreases in foraminiferal density, S, E, and H, relative to the down-core intervals as well as previous surveys. Non-metric multidimensional scaling (nMDS) analysis suggested that a 3-fold increase in polycyclic aromatic hydrocarbon (PAH) concentration in the surface interval, relative to the down-core interval, was the environmental driver of benthic foraminiferal variability. These records suggested that the benthic foraminiferal recovery time, following an event such as the DWH, was on the order of 1–2 years.