Triiodinated benzoic acid derivatives are widely used as contrast media for medical examinations and are found at high concentrations in urban aquatic environments. During bank filtration, deiodination of iodinated contrast media has been observed under anoxic/anaerobic conditions. While several bacterial strains capable of dechlorination and debromination have been isolated and characterized, deiodination has not yet been shown for an isolated strain. Here, we investigate dehalogenation of iodinated contrast media (ICM), triiodobenzoic acids (TIBA), and analogous chlorinated compounds by Dehalococcoides mccartyi strain CBDB1 and its corrinoid co-factor vitamin B₁₂. No cell growth of CBDB1 was observed using iodinated compounds as electron acceptor. Only negligible deiodination occurred for ICM, whereas 2,3,5-TIBA was nearly completely deiodinated by CBDB1 without showing cell growth. Furthermore, TIBA inhibited growth with hexachlorobenzene which is usually a well-suited electron acceptor for strain CBDB1, indicating that TIBA is toxic for CBDB1. The involvement of CBDB1 enzymes in the deiodination of TIBA was verified by the absence of deiodination activity after heat inactivation. Adding iodopropane also inhibited the deiodination of TIBA by CBDB1 cells, indicating the involvement of a corrinoid-enzyme in the reductive TIBA deiodination. The results further suggest that the involved electron transport is decoupled from proton translocation and therefore growth. Graphical abstract

Atrazine (ATR) is a common herbicide used worldwide. It is a potent endocrine disruptor that causes hormonal imbalance. We investigated the modulatory role predisposed by glycyrrhizic acid (GA) against the hazardous effects caused by the ATR in the rabbit spleen. Sixty rabbits were assigned into 4 groups. The first group is the negative control; the ATR group received 1/10 of the oral LD ₅₀ ATR; the GA group received 50 mg/kg body weight daily intraproteinally; and group 4 received both ATR and GA concurrently. ATR and GA administrations were done for 60 days. ATR-induced humoral immunotoxicity was illustrated by decreased serum total protein, albumin, and globulin levels and rabbit hemorrhagic disease virus antibody titer, 4 weeks after vaccination. Moreover, upregulation of spleen Fas and caspase-III genes was recorded in ATR-exposed rabbits. Clear splenocyte apoptosis was observed in the immunohistochemical examination by the caspase-III technique. GA diminished the ATR-induced splenocyte apoptosis through downregulation of Fas and caspase-III expressions. In conclusion, our findings bounced a new perspective into the mechanism by which ATR induces immunotoxicity and assumed the potential modulatory role of GA.

The water of urban landscape park is often confronted with microalgal blooms due to its stagnancy. Bioremediation using the combined emergent and submerged plants to control the microalgae growth was investigated in the present study. Two water bodies (Bei and Xin) of Yuyuantan Park in Beijing were selected for the field experiments, and the other lakes with different vegetation of macrophytes were selected as the comparison. The concentrations of chlorophyll a (chl a), chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP), and water temperature and transparency were monitored before and after bioremediation from 2015 to 2017. Results showed that the effects of microalgal inhibition were more significant 2 years after bioremediation. Specifically, the chl a of Dong Lake without any vegetation of macrophytes was up to 65.1 μg/L in summer of 2017, while the Bei and Xin Lakes was only 6.2 and 11.3 μg/L, respectively. In addition, the water quality and transparency also improved, with water bodies being crystal clear. Submerged plants played major roles in microalgal control and water quality improvement, compared to the lakes with only emergent plants. The intensity of humic acid-like substances in three-dimensional fluorescent spectra was stronger for the lakes with submerged plants.

Muscle, liver and kidney of 21 Barbary sheep (Ammotragus lervia) from Mosor Mountain, Croatia, were sampled to quantify the activity of caesium and potassium radionuclides and five toxic and ten essential stabile elements in order to establish reference values for this species and to evaluate the potential of Barbary sheep tissues to reflect environmental pollution. We also assessed seasonal diet (botanical composition and dry matter content) of Barbary sheep based on analyses of a rumen content of culled animals. None of the 19 plant species (mostly grasses) identified as part of the Barbary sheep diet is known as a stabile element or radionuclide hyperaccumulator. Measured levels reflected low environmental pollution with arsenic, cadmium, mercury and lead, with levels generally less than those reported for wild herbivorous ungulates. Methodological differences (detection limit of elements in muscle) were shown to hamper interpretation and comparison of the Toxic Contamination Index (TCI) values with those published for other species. There was no homeostasis disturbance of trace elements in Barbary sheep, either due to inadequate intake via food or as an adverse effect due to a high toxic metal(loid) burden. Consumption of the muscle and liver of wild Barbary sheep can be considered safe for the health of adult consumers regarding toxic metal(loid)s and radioactive caesium, though the liver should be avoided as a food item in vulnerable population groups due to the possible adverse effects of cadmium and lead. Otherwise, muscle and liver are a rich source of copper, iron, selenium and zinc for consumers and, as such, can benefit the overall dietary intake of essential elements.

Metal-oxide nanoparticles (NPs), as a new emerging technological compound, promise a wide range of usage areas and consequently have the potential to cause environmental toxicology. In the present work, aluminum (Al₂O₃), copper (CuO), and titanium (TiO₂) nanoparticles (NPs) were administered via oral gavage to mature female rats (Rattus norvegicus var. albinos) for 14 days with a dose series of 0 (control), 0.5, 5, and 50 (mg/kg b.w./day). Enzyme activities of the antioxidant system such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione S-transferase (GST), and glutathione reductase (GR) in the liver were measured. Transmission electron microscope (TEM) images of the liver were taken to demonstrate NP accumulation and distribution in liver tissue. Data showed that all NPs caused some significant (P > 0.05) alterations in the activities of antioxidant enzymes. CAT activity increased after CuO and TiO₂ administrations, while SOD activity decreased after Al₂O₃ administration. The activities of enzymes associated with glutathione (GR, GPx, GST) metabolisms were also significantly altered by NPs. GPx activity increased in rats received Al₂O₃, CuO NPs, while GR activity increased only by Al₂O₃. However, there were increases (TiO₂) and decreases (CuO) in GST activity in the liver of rats. TEM images of the liver demonstrated that all NPs accumulated in the liver, even at the lowest dose. This study indicated that the antioxidant enzymes in the liver of rats were affected by all NPs, suggesting the antioxidant system of rats suffered after NP administration.

This study investigates the removal of selected pharmaceuticals, as recalcitrant organic compounds, from synthetic wastewater using an electro-membrane bioreactor (eMBR). Diclofenac (DCF), carbamazepine (CBZ), and amoxicillin (AMX) were selected as representative drugs from three different therapeutic groups such as anti-inflammatory, anti-epileptic, and antibiotic, respectively. An environmentally relevant concentration (10 μg/L) of each compound was spiked into the synthetic wastewater, and then, the impact of appending electric field on the control of membrane fouling and the removal of conventional contaminants and pharmaceutical micropollutants were assessed. A conventional membrane bioreactor (MBR) was operated as a control test. A reduction of membrane fouling was observed in the eMBR with a 44% decrease of the fouling rate and a reduction of membrane fouling precursors. Humic substances (UV₂₅₄), ammonia nitrogen (NH₄-N), and orthophosphate (PO₄-P) showed in eMBR removal efficiencies up to 90.68 ± 4.37, 72.10 ± 13.06, and 100%, respectively, higher than those observed in the MBR. A reduction of DCF, CBZ, and AMX equal to 75.25 ± 8.79, 73.84 ± 9.24, and 72.12 ± 10.11%, respectively, was found in the eMBR due to the enhanced effects brought by electrochemical processes, such as electrocoagulation, electrophoresis, and electrooxidation.

Varying concentrations of soil Cr(VI) were used in order to explore the tolerance thresholds and phytoremediation potential of Greek oregano (Origanum vulgare), in a pot experiment conducted outdoors. Oregano exhibited a rather exceptional capacity to bioaccumulate Cr in both the aerial part (up to 1200 mg of total Cr kg⁻¹ DM) and the root—reaching 4300 mg kg⁻¹ DM when grown in soil [Cr(VI)] of 150–200 mg kg⁻¹. Plant responses indicated that there was a threshold set at 100 mg Cr(VI) kg⁻¹ in the soil, above which the following results were recorded: (i) a restriction of Cr translocation from below- to above-ground plant part, (ii) a raise of the soil-to-root Cr transfer, and (iii) the Cr(III) evolution from the reduction of Cr(VI) was significantly decelerated in the root and accelerated in the aerial part. Soil [Cr] that surpassed this threshold challenged plant tolerance, resulting in a dose-dependent reduction of growth and antioxidant phenolics pool. Nonetheless, the significant Cr uptake capacity at plant level accounted for the considerably short remediation time (i.e., 29 years at soil [Cr(VI)] of 150 mg kg⁻¹) calculated according to these results. The overall performance of oregano indicated that phytoremediation would be feasible at sites with Cr contamination levels ranging within the above-defined thresholds.

The low-cost composite film was prepared by incorporating chitosan, berry soap fruit extract (rarasaponin), and bentonite as the raw materials. The produced chitosan/rarasaponin/bentonite (CRB) composite exhibits outstanding adsorption capability toward copper metal ions (Cu(II)). A series of static adsorption experiments were carried out to determine the isotherm and kinetic properties of CRB composite in the adsorption process. The adsorption equilibrium shows a good fit with the Langmuir isotherm model; the CRB composite has maximum uptake of Cu (II) of 412.70 mg/g; the kinetic adsorption data exhibit a good fit with the pseudo-second-order model. The thermodynamic parameters, ΔH°, ΔG°, and ΔS°, obtained from the isotherm data indicate that the uptake of copper ions by CRB composite is more favored at low temperatures. This study shows that physicochemical modified adsorbent, namely CRB composite, can remove Cu (II) better than pristine adsorbent of AAB and chitosan. The CRB composite also shows potential reusability.

The lignin-based carbon fibers were prepared by electrospinning followed by stabilization, carbonization, and activation (i.e., steam activation, one-step KOH activation, and metal activation). The effect of carbonization temperature on prepared carbon fibers (CFs) was investigated. As a result, 800 °C is the most suitable carbonization temperature because the prepared carbon fibers possess greater specific surface area and pore volume. With the help of various characterization methods, the structural characteristics of the activated carbon fibers (ACFs) prepared by the three activation methods and the adsorption performance of toluene were compared. It was observed that the activated carbon fibers prepared by KOH one-step activation method (ACFK) exhibited higher specific surface area (1147.16 m²/g) and greater toluene adsorption (463 mg/g). Particularly, abundant microporous structures and surface functional groups play a vital role in the adsorption process. Further, the adsorption performance of toluene onto ACFK was further investigated in a gas-phase dynamic adsorption system and the results showed that ACFK has great potential application in adsorption of volatile organic compounds.

Fluxes of methane (CH₄) and nitrous oxide (N₂O) from two rice varieties, Huayou 14 and Hanyou 8, were monitored using closed chamber/gas chromatography method. Huayou 14 is a commonly grown variety of rice whereas Hanyou 8 is a water-saving and drought-resistant rice (WDR) variety. Low soil volumetric water content (VWC) existed in the treatments on the slope (W5 < W4 < W3 < W2). On the slope, rice yields of Hanyou 8 decreased by 12–39%, and Huayou 14 by 11–46% as compared to the plots on the flat. The total compatible solutes in Hanyou 8 had a greater variational range than Huayou 14. Compared to W1, CH₄ emissions from W2–W5 decreased by 58–86% in Hanyou 8 and 38–86% in Huayou 14, whereas those of N₂O increased by 26–121% in Hanyou 8 and 49–189% in Huayou 14 across both two seasons, which was mainly because the VWC varied in W2–W5 treatment. Under the treatments in the slope (W2, W3, W4, and W5), the global warming potential (GWP) was dominated by N₂O emissions, which accounted for 69–90% of the GWP. Hanyou 8 had greater tolerance for water stress than Huayou 14 did, as evident from the smaller reductions in rice yield and greater variational range of total compatible solutes content. Water stress could reduce CH₄ emissions but decrease N₂O emissions for both rice varieties. This results suggest that planting WDR varieties under water shortage irrigation (such as W4, W5) will be able to maintain rice yields and reduce the GWP with less water.