Present study investigates the coagulation ability of Plantago ovata (P. ovata) seed extracts for turbidity removal. The active coagulant agents were successfully extracted from P. ovata seeds using different solvents such as distilled water (PO-DW), tap water (PO-TW), NaCl (PO-NaCl), and ammonium acetate (PO-AA). Experiments were conducted in batch mode for initial turbidity such as 500 NTU (high), 150 NTU (medium), and 50 NTU (low). Results demonstrated that P. ovata extracts are less efficient in low turbidities, while PO-NaCl was found to provide high coagulation activity in all initial turbidity concentrations compared to other extracts. PO-NaCl was able to remove 98.2, 94.9, and 80.2% of turbidity from water having in initial turbidities of 500, 150, and 50 NTU, respectively. Coagulation activity of the extract was the best when the extraction was performed for 50 min at room temperature. Jar test procedure with the coagulation time of 1 min and flocculation time of 30 min was optimized, irrespective of the initial turbidity. The optimum settling time for 500, 150, and 50 NTU water samples were 20, 30, and 90 min, respectively. PO-NaCl was used in different pH turbid solutions and it was found to be working very efficiently in alkaline conditions. The coagulation efficiency of the coagulant stored in refrigerator was higher than that stored at room temperature. Thus, the natural coagulants extracted from P. ovata seeds revealed to be effective for turbidity removal.

In this study, in-house isolated laccase isoforms, i.e., Lac-I and Lac-II of the basidiomycete Pycnoporus sanguineus (CS43), were evaluated in relation to their Remazol Brilliant Blue R (RBBR) dye degradation capacity. A modified Dhouib medium additionally supplemented with 3% ethanol as a secondary inducer was used to propagate P. sanguineus CS43 for enhanced production of laccase under liquid state fermentation. The crude laccase extract was purified by passing through ion exchange diethylaminoethanol (DEAE)-Sepharose and gel filtration-based Sephadex G-200 column chromatography. The purified laccase fractions were subjected to the electrophoresis, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed two laccase isoforms Lac-I and Lac-II with 66 and 68 kDa, respectively. To explore the industrial applicability, for RBBR dye, degradation efficiencies ranged from 82 to 88% after 3 h of incubation for both; Lac-I and Lac-II at both concentrations were recorded. However, with 8 U/mL, the degradation ranged between 70 to 80% during the first 5 min of incubation. Enhanced degradation of RBBR dye was obtained in the presence of violuric acid and N-hydroxypthalamide as laccase mediators. Finally, using RBBR as a substrate kinetic characterization of both Lac-I and Lac-II isoforms was performed that revealed K ₘ (0.243 and 0.117 mM for Lac-I and Lac-II) and V ₘₐₓ (1.233 and 1.012 mM/Sec for Lac-I and Lac-II) values, respectively.

This study sought to analyze the effects of the herbicide quinclorac on body condition indices; plasma levels of corticosterone, glucose, and uric acid; activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST); and levels of lipid peroxidation (LPO) in the liver and caudal muscle of American bullfrog (Rana catesbeiana) tadpoles. After a 7-day acclimation period, animals were exposed to four concentrations (0.05, 0.1, 0.2, and 0.4 μg/L) of herbicide for a further 7 days. Then, blood samples were obtained, animals were euthanized, and the liver and caudal muscle resected. Levels of corticosterone and uric acid were reduced in tadpoles exposed to the highest concentration of herbicide, and this reduction was preceded by an increase in glucose levels. In the liver tissue, LPO was increased after exposure to 0.1 μg/L quinclorac, followed by a return to baseline values in the remaining concentrations; this response was accompanied by an increase in SOD and GST and reduction of tissue protein levels. At the highest concentration, a reduction in activity of all enzymes was observed, with protein returning to control-like levels. In muscle, SOD and GST levels declined with exposures up to 0.1 g/L and 0.4 μg/L, respectively, whereas LPO decreased in animals exposed to 0.1 μg/L. These results suggest participation of nonenzymatic antioxidant defenses, as demonstrated by the reduction in uric acid levels. Exposure to the range of quinclorac concentrations used in this study slowed body mass and length gain, reduced corticosterone levels, and modulated antioxidant defenses. Graphical abstract ᅟ

Elevated bacteria concentrations have led to the impairment (e.g., closures of shellfisheries and recreational beaches) of coastal waters. Although many previous studies have suggested that wastewater inputs can lead to elevated fecal indicator bacteria (FIB) concentrations in surface waters, few studies have quantified wastewater-associated FIB exports at the watershed scale. The goal of this study was to estimate bacterial exports at the watershed scale based on wastewater management approach (septic vs. sewer). Six watersheds (three exclusively on septic and three exclusively served by a sewer system) were selected for water quality assessment and comparison. Streams were monitored approximately monthly from August 2011 to June 2012 during baseflow conditions. Additionally, three storms were monitored. Samples were collected in sterile 100-mL bottles and analyzed for Escherichia coli concentrations. Discharge from streams was measured and bacterial exports were estimated by multiplying discharge by E. coli concentration. The results revealed that (1) during baseflow conditions, septic watersheds contained elevated stream discharge and E. coli concentrations and exports as compared to sewer watersheds; (2) warmer months had elevated E. coli watershed exports compared to colder months in both septic and sewer watersheds; and (3) storms significantly increased watershed E. coli exports in both septic and sewer watersheds. Storms significantly increased watershed E. coli exports in both septic and sewered watersheds, but E. coli counts in sewered watersheds were considerably greater likely due to greater impervious surface coverage and or leaky sewer infrastructure. These findings in conjunction with previous studies suggest that septic systems may play a pivotal role in the delivery of FIB to receiving waters, particularly during baseflow conditions.

Microplastics (MPs) in sediments from the complex lagoon-channel of Bizerte were investigated, for the first time, to evaluate the occurrence and abundance of MPs in Tunisia. After density separation in saline solution, MPs were counted by a stereomicroscope. The number of MPs was at the range of 3–18 items/g sediment (3000–18,000 items/kg dry sediment) and the most contaminated site was of Menzel Abderrahmane (MA) followed by Carrier Bay (CB), Menzel Jemil (MJ) and Channel of Bizerte (C). The MPs gathered during the survey varied in size from 0.3 to 5 mm, and appear in a variety of shapes and colours. The dominant shape was fibre (88.88% in MA, 91.00% in CB, 82.35% in C and 21.05% in MJ). The rest of MPs are fragments whilst no micro beads were found. Colours are clear, white, blue, green, red and black. Cities discharges, fishing activity and industrial production sites are the most likely sources of MPs. This first work provides original data on the presence of MPs that determines their bioavailability to organisms as seafood, and then possibly transfers of to human. The high MP concentrations registered in the complex lagoon-channel of Bizerte suggest that this site is a hotspot for MP pollution and there is an urgency to understand their origins and effects on marine life. The results will provide useful background information for further investigations.

Effects of ethanol and nitrate on linear alkyl benzene sulfonate (LAS) degradation were investigated using central composite design. At experimental design, removal of 99.9% was observed in batch reactors (1 L) with 9.8 to 41.2 mg L⁻¹ of LAS. The batch reactors were kept under agitation at 120 rpm and 30 °C. Ethanol (co-substrate) and nitrate (electron acceptor) were statistically significant factors (p < 0.05) in surfactant removal. Optimal values were 97.5 and 88 mg L⁻¹ for ethanol and nitrate, respectively. LAS removal was kinetically investigated by varying surfactant concentration while using optimal values. Batch I (27 mg L⁻¹ LAS) exhibited greater degradation rate (KᴸᴬS) (0.054 h⁻¹) in the presence of ethanol and nitrate. Nonetheless, in Batch II (60 mg L⁻¹ LAS), the KᴸᴬS values decreased in those reactors probably due to inhibition by excess substrate for same concentrations of nitrate and ethanol added in reactors. As LAS concentration increased, the dominance of bacterial populations also increased, whereas diversity index decreased from 2.8 (inoculum) to 2.4 and 2.5 for reactors with both added nitrate and ethanol and those with only added ethanol, respectively. Probably, a selection of microbial populations occurred in relation to LAS concentration. The nitrate and ethanol, at able concentration, made it possible the induction of denitrifying microrganisms foward to LAS removal.

The operation variables and electro-kinetic field (EKF) were investigated to enhance the remediation of arsenic (As)- and cesium (Cs)-contaminated soils with soil washing. Extractant types, concentrations, liquid/solid (L/S) ratios, solution pH values, washing temperatures, and agitation modes were important criteria to determine the efficiency of soil washing. The KH₂PO₄ was proved to be a suitable alternative to Na₂EDTA in extracting As and Cs from contaminated soils. A 2-h washing with KH₂PO₄ at concentration of 0.01 M and L/S ratio of 20 mL g⁻¹ showed the most efficient washing performance. In addition, the lower solution pH, higher temperature, and ultrasound also favored soil washing of As and Cs with KH₂PO₄. The EKF greatly enhanced metals extraction with soil washing. It offered acidic soil environment around the anode areas for the release of soluble Cs from its soil solid-phase components before soil washing. Moreover, the alkalization around the cathode areas also benefited the desorption of stable As since labile As were mainly presented in anionic forms. The effect of CA for neutralizing OH⁻ was proved to be limited, while the reversed subsequent EKF process effectively alleviated Cs precipitation generated during the initial EKF process. It also effectively restored soil pH altered by the initial EKF. The overall EKF (4 V cm⁻¹) enhanced removal efficiency of As and Cs with soil washing from the anode area was 37 and 31%, respectively. Higher removal of As (52%) was obtained in the cathode area. Moreover, the reversed EKF resulted in another 28% removal of Cs in the initial cathode area which showed the capacity of EKF on continuous soil metal remediation.

Heavy metals, chemical elements considered toxic at certain concentrations, can be considered potential threats to plants, animals, and biological resources of a particular ecosystem. Among them, mercury and aluminum, when involved in bioaccumulation processes, can cause damage to various organ systems of both animals and plants. In vegetables, heavy metals produce reactive oxygen species (ROS), which are involved in the occurrence of malformations and deficits in the growth of roodets and plumule of several species of plants, which justifies the study of natural antioxidant agents that may come to reverse or ameliorate the deleterious effects caused by these compounds. In this sense, this study aims to evaluate the cytoprotective effect of hydroethanolic extract of Stryphnodendron rotundifolium Mart., species popularly known as “barbatimão” against the heavy metals mercury and aluminum in vegetable model, because of its known antioxidant potential. To this end, there was the cytoprotection test in microbial and lettuce seeds (germination) in order to ascertain the potential of the said extract on the protection of roots and stem this. It was observed that the extract showed no allelopathic effect on lettuce seeds at a concentration of 32 μg/mL and in combination with HgCl₂ and AlCl₃, it enabled a higher growth in the roodets and stem Lactuta sativa L. These results demonstrated that the extract of Stryphnodendron rotundifolium can be an alternative to solve the problem with soil contamination by heavy metals, showing thus its promising potential cytoprotective in plant species.

Hexavalent chromium (Cr(VI)), which has been classified as a Group A human carcinogens list by the United States Environmental Protection Agency, possesses stronger biological toxicity, and its discharge into farmland has become a pressing environmental problems. To screen the cost-efficient Cr(VI)-contaminated soil in situ amended materials, the effects of ordinary zero-valent iron (ZVI), nanoscale zero-valent iron (nZVI), biochar (B), biochar/zero-valent iron (BZVI), and biochar/nanoscale zero-valent iron (BnZVI) on the immobilization of Cr(VI) in spiked soil (Cr(VI) = 325 mg kg⁻¹, Crₜₒₜₐₗ = 640 mg kg⁻¹) were compared in this paper. After 15 days remediation by those materials, toxicity characteristic leaching procedure and physiological-based extraction test showed that the Cr(VI) leachability and bioaccessibility were reduced by 14–92% and 4.3–92% respectively, and the order of immobilization was found to be nZVI > BnZVI > BZVI > ZVI > B. Moreover, sequential extraction procedure indicated that all materials can increase the proportion of the residual Cr, and nZVI had the most significant effect. Plant seedling growth test proved that the nanoscale zero-valent iron was able to reduce the toxicity of chromium in plants greatly in a short time, while BnZVI treatment is more favorable to the growth of plants. To sum up, the nano zero-valent iron and biochar combined treatment not only removed Cr(VI) and immobilized total chromium efficiently but also enabled plant growth in relative high chromium-containing soil.

Currently, the use of nanotechnologies is in rapid expansion, which entails increasing risks of environmental contamination by nanoparticles. Many studies describe the toxic effects on human cells, but little is known about the possible adverse effects on plants. Currently, various nanoparticles are often detected in streams, wastewater, and sewage due to widespread nanoparticle uses. We studied the accumulation and the effect of metal oxide nanoparticles together with their bulk counter particles and soluble metal salts on the growth of a wetland plant species true fox-sedge (Carex vulpina L.). The concentration 100 mg/l of copper nanoparticles significantly affected the growth of the plants, roots characteristics, and content of the photosynthetic pigments in leaves, while the same concentration of iron nanoparticles did not reduced any of the measured items. Using the bulk materials, the effect was very similar.