The chitosan-stabilized ferrous sulfide nanoparticles were loaded on biochar to prepare a composite material FeS-CS-BC for effective removal of hexavalent chromium in water. BC and FeS-CS-BC were characterized by Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses. Batch experiments were employed to evaluate the Cr(VI) removal performance. The experimental results showed that the removal rate of Cr(VI) by FeS-CS-BC(FeS:CS:BC = 2:2:1) reached 98.34%, which was significantly higher than that of BC (44.58%) and FeS (79.91%). In the pH range of 2–10, the removal of Cr(VI) by FeS-CS-BC was almost independent of pH. The limitation of coexisting anions (Cl⁻、SO₄²⁻、NO₃⁻) on Cr(VI) removal was not too obvious. The removal of Cr(VI) by FeS-CS-BC was fitted with the pseudo-second-order dynamics, which was a hybrid chemical-adsorption reaction. The X-ray photoelectron spectroscopy (XPS) analysis result showed that Cr(VI) was reduced, and the reduced Cr(VI) was fixed on the surface of the material in the form of Cr(VI)–Fe(III). Graphical abstract Removal of hexavalent chromium from wastewater by FeS-CS-BC composite synthesized by impregnation.

The aim of this study was to investigate the autonomic modulation of heart rate in healthy individuals exposed to long-term air pollution through geometric methods. We analyzed data from 109 healthy adults aged 18 to 49, divided into three groups according to the exposure time: period 0 to 15 years of exposure (n = 29), more than 15 years of exposure (n = 31), and control group (n = 49). For the analysis of heart rate variability (HRV), heart rate was recorded beat-to-beat for 20 min in the sitting position. The RR intervals were transformed into geometric indexes, and from them, we calculated the RRTri (triangular index), TINN (triangle interpolation of histogram of intervals NN), and Poincaré plot (SD1, SD2, and SD1/SD2). Significantly lower values were observed in the group of individuals exposed to air pollution for more than 15 years compared with the group of individuals exposed to air pollution for a period of 0–15 years and those not exposed for the RRTri (11.5 vs 13.8 vs 14.0), SD1 (16.4 vs 20.5 vs 20.6), SD2 (60.5 vs 68.1 vs 72.5), and SD1/SD2 (0.27 vs 0.34 vs 0.31), with the effect of this difference being considered large (RRTri), medium (SD1, SD1/SD2), and small (SD2). TINN was not significantly different among groups (198.2 vs 223.1 vs 233.6). Healthy individuals exposed to air pollution for more than 15 years present an autonomic imbalance, characterized by lower parasympathetic modulation and overall HRV.

Around 3 billion people worldwide use solid biomass fuels for cooking. Exposure to indoor biomass smoke is an important cause of COPD and therefore a target of many public health interventions, such as usage of improved cookstoves. The aim of our study was to show whether usage of improved cookstoves can lead to relevant improvement in lung function and CAT-score in a well characterized population including a subgroup of this population with preexisting airway obstruction. Interviews and spirometry were performed in Congolese women living in an UNHCR (United Nations High Commissioner for Refugees) refugee camp in Rwanda before (baseline, BL) and 9 months after (follow-up, F9) they received an energy-efficient cookstove (Save80) and were trained how to use it. Two hundred sixty-two women completed both spirometry and interview appropriately at BL and F9 and were included in per protocol (pp) analysis, which showed no change in mean FEV1. The predefined subgroup of this population with airway obstruction at baseline (N = 31) showed a significant FEV1 increase (FEV1F₉ = 1.70 L; p < 0.01 vs FEV1BL = 1.58 L, p < 0.01). Median CAT-scores were significantly lower in the F9 assessment. Our data indicate that usage of improved cookstoves has a positive impact on respiratory health especially in individuals with preexisting airway obstruction. Further studies to investigate long-term outcome are warranted.

Pentachlorophenol (PCP) is an organochlorine compound that is used as pesticide, biocide, and wood preservative. PCP is highly toxic and carcinogenic. It has been detected in food and several consumable products. The toxicity of PCP is thought to be due to generation of oxidative stress in cells. We examined whether the dietary antioxidant catechin can attenuate or protect human erythrocytes and lymphocytes against PCP-induced cytotoxicity and genotoxicity, respectively. Human erythrocytes were treated with increasing concentrations of catechin (0.05–2.5 mM) for 30 min followed by addition of 0.75 mM PCP and further incubation for 4 h at 37 °C. Hemolysates were prepared and assayed for various biochemical parameters. Treatment with PCP alone increased the generation of reactive oxygen and nitrogen species, lipid and protein oxidation, and damaged the plasma membrane, when compared to PCP untreated (control) cells. It significantly decreased glutathione level, total sulfhydryl content, and cellular antioxidant power. PCP treatment lowered the activity of antioxidant enzymes and inhibited enzymes of glucose metabolism. However, prior incubation with catechin attenuated the PCP-induced changes in all these parameters in a catechin concentration-dependent manner. Scanning electron microscopy of erythrocytes confirmed these biochemical results. PCP treatment converted the normal discoidal erythrocytes to irregularly contracted cells, acanthocytes, and echinocytes but the presence of catechin inhibited these morphological changes and erythrocytes retained their biconcave shape to a large extent. Genotoxicity was studied in human lymphocytes by single-cell gel electrophoresis (comet assay). It showed strand breaks and longer comet tail length in PCP alone treated cells. The comet tail length was reduced in the catechin +PCP-treated lymphocytes showing that catechin protected cells from PCP-induced DNA damage. These results show that catechin protects human blood cells against PCP-induced oxidative damage.

Assessment of pesticides toxicity using zebrafish early life stages is relevant for aquatic systems safety. This study aimed to evaluate the short-term effects of 2,4-dichlorophenoxyacetic acid (2,4-D) on zebrafish (Danio rerio) embryos from 3 h post fertilization to 96 hpf. A set of 2,4-D concentrations ranging from 0.32 to 80 mg/L were tested and median lethal concentration (LC₅₀) at 96-h was calculated as 2.86 mg/L. A sub-teratogenic concentrations range from 0.02 to 0.8 mg/L was then used to assess effects at ontogenic, biochemical, and behavioral levels. The main developmental defects were tail deformities and pericardial edema at concentrations equal or above 0.32 mg/L. Cholinesterase activity (at 96 hpf) and larvae swimming behavior (at 120 hpf) were affected even at the lowest tested dose (0.02 mg/L). The behavior analysis was a sensitive endpoint, with a decrease in the swimming distance of exposed larvae during light period. The effect of 2,4-D in ChE was translated by an inhibition of the enzyme activity in all treated groups. These findings demonstrate that 2,4-D can alter the cholinergic system by affecting ChE activity which may be involved in the locomotion reduction of exposed larvae and emphasize the potential of neurotransmission and behavioral endpoints as early warning signs of herbicides contamination in aquatic ecosystems.

Biocides are added to or applied on building materials to prevent microorganisms from growing on their surface or to treat them. They are leached into building runoff and contribute to diffuse contamination of receiving waters. This review aimed at summarizing the current state of knowledge concerning the impact of biocides from buildings on the aquatic environment. The objectives were (i) to assess the key parameters influencing the leaching of biocides and to quantify their emission from buildings, (ii) to determine the different pathways from urban sources into receiving waters and (iii) to assess the associated environmental risk. Based on consumption data and leaching studies, a list of substances to monitor in receiving water was established. Literature review of their concentrations in the urban water cycle showed evidences of contamination and risk for aquatic life, which should put them into consideration for inclusion to European or international monitoring programs. However, some biocide concentration data in urban and receiving waters is still missing to fully assess their environmental risk, especially for isothiazolinones, iodopropynyl carbamate, zinc pyrithione and quaternary ammonium compounds, and little is known about their transformation products. Although some models supported by actual data were developed to extrapolate emissions on larger scales (watershed or city scales), they are not sufficient to prioritize the pathways of biocides from urban sources into receiving waters during both dry and wet weathers. Our review highlights the need to reduce emissions and limit their transfer into rivers and reports several solutions to address these issues.

The disposal of chromium (Cr) containing wastewater in surface water bodies without prior treatment is a serious threat to humans, animals, and plants. A novel nanocomposite (CSB/ZnO) of cotton stalks biochar (CSB) with ZnO nanoparticles was synthesized for the removal of Cr (VI) ions from contaminated water at batch scale. The impact of adsorbent dosage (1–4 g/L), initial Cr (VI) levels (25–200 mg/L), pH (2–8), and interaction time (0–180 min) was assessed for the removal of Cr (VI) from contaminated water. The Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), and point of zero charge (PZC) characterization showed successful impregnation of ZnO particles on CSB with improved surface characteristics. The maximum adsorption (qₘₐₓ) of CSB and CSB/ZnO was 54.95 and 107.53 mg Cr/g, respectively that is relatively higher than various previously studied adsorbents. The experimental isothermal data better fitted with the Freundlich model in comparison with other isotherm models while adsorption kinetics well corroborated with the pseudo-second-order model. The results revealed that doping of biochar with metallic nanoparticles (CSB/ZnO) proved very effective (99.6% at 50 mg/L) with high reusability (91%) after five adsorption/desorption cycles and seems a suitable strategy for the decontamination of Cr (VI) contaminated waters.

Lead (Pb) is an environmental toxicant; its consumption can induce renal deficits. In this study, we explored the possible protective efficiency of Moringa oleifera extract (MOE) against lead acetate (PbAc)-mediated reprotoxicity. Four experimental groups of seven rats each were used: control, PbAc, MOE, and MOE+PbAc groups. All groups were given their respective treatment for 4 weeks. PbAc impaired the oxidative/antioxidative balance in the renal tissue, as shown by the decreased antioxidant proteins (glutathione, glutathione reductase, glutathione peroxidase, catalase, and superoxide dismutase) and increased oxidants (lipid peroxidation and nitric oxide). Additionally, PbAc enhanced the progression of kidney inflammation by increasing tumor necrosis factor-alpha, interleukin-1 beta, and nuclear factor kappa B associated with upregulation of inducible nitric oxide synthase. Moreover, a dysregulation in the apoptotic-regulating proteins (Bax, caspase-3, and Bcl2) were recorded upon PbAc exposure. Remarkably, MOE oral administration restored redox homeostasis, suppressed the inflammatory and apoptotic responses in the kidney tissue. Our findings point out that MOE could be used as an alternative remedy to overcome the adverse effects of Pb exposure, which may be due to its potent antioxidant, anti-inflammatory, and anti-apoptotic effects.

Toxic metal(loid)s released from tailing residues of mining operations have become a global issue with regard to environmental impacts. Biochar derived from the agriculture waste is considered as a cost-effective and stable material, which could be applied for remediation of sites contaminated with toxic metal(loid)s. In the present study, tailings were amended for 90 days with increasing concentrations of Arundo donax L. stem-derived biochar (ASBC; at 0, 1, 3, and 5%). The 7-day wheat seed germination toxicity test was then used to assess the bioavailability of toxicants in aqueous leachates of the biochar-amended tailing samples. Concentrations of As, Cd, Cu, Pb, and Sb in leachates and the Community Bureau of Reference chemical fractions were determined using ICP-OES. The results indicated that tailing leachates were phytotoxic, an effect that was partially decreased due to increasing concentrations of ASBC, with maximum effects (∼47% of tailing phytotoxicity) occurring at 3% ASBC. Results of further fractionation analyses indicated that increasing concentrations of ASBC amendment decreased the mobile fractions of Cd, Cu, and Pb in tailing samples, but increased the mobilities of As and Sb. A novel approach using the relative toxicity index (= sum of toxicities of individual potentially toxic elements) indicated that the toxicity of the tailings decreased when As was not present, since As decreased the biochar-reduced toxicity. Our results suggest that the ability of using biochar to decrease toxicity in tailings (by sequestration of cationic metals such as Cd, Cu, and Pb) is limited by its inability to immobilize oxyanionic metalloids such as As and Sb.

The present study was designed to see the influence of selenium (Se) and sulphur (S) in the alleviation of arsenic (As)-induced stress in Brassica juncea plant. Se-induced alterations in physiological and biochemical responses due to deficient S (DS), normal S (NS) and additional S (AS) conditions were evaluated in 14-day-old seedlings of B. juncea variety Varuna. During the last 7 days of the 14-day-old seedlings, supplementation with arsenite (Asᴵᴵᴵ, 300 μM) alone and its combination with selenite (Seᴵⱽ, 50 μM) along with different S treatments was done which are as follows: (i) control; (ii) As; (iii) As+Se+DS; (iv) As+Se + NS; (v) As+Se + AS. Experimental results showed that the application of AS in spite of NS supplied with Se influenced plant growth, oxidative stress and thiol-ascorbate-related parameters more prominently under As stress. The plants with As+Se+AS treatment exhibited lower ROS (superoxide and hydrogen peroxide ion), malondialdehyde (MDA) accumulation and lipoxygenase activity with increased activities of superoxide dismutase, catalase and ascorbate peroxidase compared with As+Se+NS condition. These plants also exhibited an increase in cysteine, non-protein thiols and phytochelatins, along with reduced, oxidised and redox content of glutathione and ascorbate. Furthermore, the application of S along with Se increased the activities of glutathione reductase, glutathione S-transferase, glutathione peroxidase, monodehydroascorbate and dehydroascorbate to minimise As stress. However, we observed that these responses were reversed under As+Se+DS condition and induced oxidative stress, which was almost similar to As only treatment. It indicated that AS nutrition potentiated Se to alleviate As-inhibited plant growth by modulating antioxidants including thiol-ascorbate-based mechanism and reducing As accumulation in B. juncea plants.