Inactivation of <Emphasis Type="Italic">Escherichia coli</Emphasis> in fresh water with advanced oxidation processes based on the combination of O<Subscript>3</Subscript>, H<Subscript>2</Subscript>O<Subscript>2</Subscript>, and TiO<Subscript>2</Subscript>. Kinetic modeling

The purpose of this work was to study the efficiency of different treatments, based on the combination of O₃, H₂O₂, and TiO₂, on fresh surface water samples fortified with wild strains of Escherichia coli. Moreover, an exhaustive assessment of the influence of the different agents involved in the treatment has been carried out by kinetic modeling of E. coli inactivation results. The treatments studied were (i) ozonation (O₃), (ii) the peroxone system (O₃/0.04 mM H₂O₂), (iii) catalytic ozonation (O₃/1 g/L TiO₂), and (iv) a combined treatment of O₃/1 g/L TiO₂/0.04 mM H₂O₂. It was observed that the peroxone system achieved the highest levels of inactivation of E. coli, around 6.80 log after 10 min of contact time. Catalytic ozonation also obtained high levels of inactivation in a short period of time, reaching 6.22 log in 10 min. Both treatments, the peroxone system (O₃/H₂O₂) and catalytic ozonation (O₃/TiO₂), produced a higher inactivation rate of E. coli than ozonation (4.97 log after 10 min). While the combination of ozone with hydrogen peroxide or titanium dioxide thus produces an increase in the inactivation yield of E. coli regarding ozonation, the O₃/TiO₂/H₂O₂ combination did not enhance the inactivation results. The fitting of experimental values to the corresponding equations through non-linear regression techniques was carried out with Microsoft® Excel GInaFiT software. The inactivation results of E. coli did not respond to linear functions, and it was necessary to use mathematical models able to describe certain deviations in the bacterial inactivation processes. In this case, the inactivation results fit with mathematical models based on the hypothesis that the bacteria population is divided into two different subgroups with different degrees of resistance to treatments, for instance biphasic and biphasic with shoulder models.

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Acute,chronic and biochemical effects of chlorothalonil on <Emphasis Type="Italic">Agalychnis callidryas</Emphasis>, <Emphasis Type="Italic">Isthmohyla pseudopuma</Emphasis> and <Emphasis Type="Italic">Smilisca baudinii</Emphasis> tadpoles

Declines of amphibian populations have been a worldwide issue of concern for the scientific community during the last several decades. Efforts are being carried out to elucidate factors related to this phenomenon. Among these factors, pathogens, climate change, and environmental pollution have been suggested as possible causes. Regarding environmental pollutants, some pesticides are persistent in the environment and capable of being transported long distances from their release point. In Costa Rica, some pesticides have been detected in protected areas, at locations where amphibian populations have declined. Information about toxicity of pesticides used in Costa Rican agriculture to amphibians is still scarce, particularly for native species.Toxicity tests with chlorothalonil, a fungicide intensively used in Costa Rica, were carried out exposing tadpoles of three Costa Rican native species: Agalychnis callidryas, Isthmohyla pseudopuma, and Smilisca baudinii in order to evaluate acute and chronic toxicity as well as the biomarkers cholinesterase activity (ChE), glutathione-S transferase activity (GST), and lipid peroxidation (LPO).96-h LC₅₀: 26.6 (18.9–35.8) μg/L to A. callidryas, 25.5 (21.3–29.7) μg/L to I pseudopuma and 32.3 (26.3–39.7) μg/L to S. baudinii were determined for chlorothalonil. These three species of anurans are among the most sensitive to chlorothalonil according to the literature. Besides, GST was induced in S. baudinii after exposure to sub-lethal concentrations of chlorothalonil while evisceration occurred in S. baudinii and A. callidryas tadpoles exposed to lethal concentrations of the fungicide. Chronic exposure to sub-lethal concentrations accelerated development in S. baudinii and caused lesions in tail of S. baudinii and I. pseudopuma tadpoles. Our results demonstrate that chlorothalonil is highly toxic to native amphibian species and that low concentrations can cause biochemical responses related to phase II of biotransformation and effects on development.     

<Emphasis Type="Italic">Ailanthus Altissima</Emphasis> and <Emphasis Type="Italic">Phragmites Australis</Emphasis> for chromium removal from a contaminated soil

The comparative effectiveness for hexavalent chromium removal from irrigation water, using two selected plant species (Phragmites australis and Ailanthus altissima) planted in soil contaminated with hexavalent chromium, has been studied in the present work. Total chromium removal from water was ranging from 55 % (Phragmites) to 61 % (Ailanthus). After 360 days, the contaminated soil dropped from 70 (initial) to 36 and 41 mg Cr/kg (dry soil), for Phragmites and Ailanthus, respectively. Phragmites accumulated the highest amount of chromium in the roots (1910 mg Cr/kg_{(dry tissue)}), compared with 358 mg Cr/kg_{(dry tissue)} for Ailanthus roots. Most of chromium was found in trivalent form in all plant tissues. Ailanthus had the lowest affinity for Cr^VI reduction in the root tissues. Phragmites indicated the highest chromium translocation potential, from roots to stems. Both plant species showed good potentialities to be used in phytoremediation installations for chromium removal.     

Physiological and biochemical responses of <Emphasis Type="Italic">Machilus ichangensis</Emphasis> Rehd. et Wils and <Emphasis Type="Italic">Taxus chinensis</Emphasis> (Pilger) Rehd. to elevated O<Subscript>3</Subscript> in subtropical China

Considerable researches have documented the negative effects of ozone on woody species in North America and Europe; however, little is known about how woody tree species respond to elevated O₃ in subtropical China, and most of the previous studies were conducted using pot experiment. In the present study, Machilus ichangensis Rehd. et Wils (M. ichangensis) and Taxus chinensis (Pilger) Rehd. (T. chinensis), evergreen tree species in subtropical China, were exposed to non-filtered air (NF), 100 nmol mol^?1 O₃ (E1) and 150 nmol mol^?1 O₃ (E2), in open-top chambers under field conditions from 21st March to 2nd November 2015. In this study, O₃ fumigation significantly reduced net photosynthesis rate (Pn) in M. ichangensis in the three measurements and in T. chinensis in the last measurement. Also, non-stomatal factors should be primarily responsible for the decreased Pn. O₃ fumigation-induced increase in malondialdehyde, superoxide dismutase, and reduced ascorbic acid levels indicated that antioxidant defense mechanism had been stimulated to prevent O₃ stress and repair the oxidative damage. Yet, the increase of antioxidant ability was not enough to counteract the harm of O₃ fumigation. Because of the decrease in CO₂ assimilation, the growth of the two tree species was restrained ultimately. The sensitivity of the two tree species to O₃ can be determined: M. ichangensis > T. chinensis. It suggests a close link between the rising O₃ concentrations and the health risk of some tree species in subtropics in the near future.     

Rapid biological synthesis of silver nanoparticles using <Emphasis Type="Italic">Leucas martinicensis</Emphasis> leaf extract for catalytic and antibacterial activity

A novel green approach for the synthesis and stabilization of silver nanoparticles (AgNPs) using water extract of Leucas martinicensis leaf has been developed. As obtained, the nanoparticles are characterized by UV-visible (UV-Vis), transmission electron microscope (TEM), and X-ray diffraction (XRD). The crystalline nature of the AgNPs is confirmed by the prominent peaks in the XRD pattern. FTIR spectra suggest that the possible biomolecules are responsible for the efficient stabilization of the sample. The effects of leaf quantity on the biosynthesis of AgNPs are investigated by UV-Vis spectrophotometer. The synthesized AgNPs are observed to have a good catalytic activity on the reduction of methylene blue by L. martinicensis leaf. This is confirmed by the decrease in absorbance maximum values of methylene blue with respect to time through UV-Vis spectrophotometer. Moreover, the antibacterial activity of synthesized AgNPs against Staphylococcus aureus, Bacillus subtilis, Salmonella typhi, and Escherichia coli are screened.     

Side effects of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> var. kurstaki on the hymenopterous parasitic wasp <Emphasis Type="Italic">Trichogramma chilonis</Emphasis>

Most of the detrimental effects of using conventional insecticides to control crop pests are now well identified and are nowadays major arguments for replacing such compounds by the use of biological control agents. In this respect, the bacterium Bacillus thuringiensis var. kurstaki and Trichogramma (Hymenoptera: Trichogrammatidae) parasitic wasp species are both effective against lepidopterous pests and can actually be used concomitantly. In this work, we studied the potential side effects of B. thuringiensis var. kurstaki on Trichogramma chilonis females. We first evidenced an acute toxicity of B. thuringiensis on T. chilonis. Then, after ingestion of B. thuringiensis at sublethal doses, we focused on life history traits of T. chilonis such as longevity, reproductive success and the time spent on host eggs patches. The reproductive success of T. chilonis was not modified by B. thuringiensis while a significant effect was observed on longevity and the time spent on host eggs patches. The physiological and ecological meanings of the results obtained are discussed.     

Biosynthesis of silver nanoparticles using <Emphasis Type="Italic">Myristica fragrans</Emphasis> seed (nutmeg) extract and its antibacterial activity against multidrug-resistant (MDR) <Emphasis Type="Italic">Salmonella enterica</Emphasis> serovar Typhi isolates

Biosynthesis of nanoparticles has received increasing attention due its effective mode of action, eco-friendly preparation methodology, and less cytotoxicity. In the present study, silver nanoparticles (AgNPs) from aqueous seed extract of Myristica fragrans (nutmeg) were characterized. Gas chromatography–mass spectrometry (GC–MS) analysis revealed the presence of bioactive components acts as effective in reducing and capping agents for converting AgNO₃ to AgNPs. The UV-Vis absorption spectrum of the biologically reduced reaction mixture showed the surface plasmon peak at 420 nm, which is the characteristic peak of AgNPs. The functional molecules present in the M. fragrans seed extract and their interaction with the AgNPs were identified by the Fourier transform infrared spectroscopy (FT-IR) analysis. X-ray diffraction (XRD) analysis confirmed the face-centered cubic crystalline structure of metallic silver nanoparticle and diameter was calculated using Scherrer’s equation. Transmission electron microscope (TEM) image showed spherical shaped particles with an average size of 25 nm. The scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS) confirmed the presence of elemental silver. The antibacterial activity of biosynthesized AgNPs was evaluated against multidrug-resistant (MDR) Salmonella enterica serovar Typhi (S. Typhi) according to agar well diffusion, MIC (minimum inhibitory concentration), and IC₅₀ (inhibitory concentration 50%). The results confirm that bacterial growth was significantly reduced in a dose-dependent manner. Further, the cytotoxic effect of biosynthesized AgNPs on rat spleenocytes was analyzed. Thus, it is suggested that the nutmeg-biosynthesized AgNPs could be a lead drug and used effectively to control the MDR S. Typhi, thereby reducing public health issues and environmental pollution.     

Green synthesis and characterization of gold and silver nanoparticles using <Emphasis Type="Italic">Mussaenda glabrata</Emphasis> leaf extract and their environmental applications to dye degradation

Plant-derived nanomaterials opened a green approach in solving the current environment issues. Present study focused on rapid microwave-assisted synthesis and applications of gold and silver nanoparticles mediated by aqueous leaf extract of Mussaenda glabrata. The synthesized nanoparticles were characterized by UV-vis, FT-IR, powder XRD, energy-dispersive X-ray spectroscopy (EDX), transmission electron (TEM), and atomic force microscopic techniques (AFM). FCC crystal structure of both nanoparticles was confirmed by peaks corresponding to (111), (200), (220), and (311) planes in XRD spectra and bright circular spots in SAED pattern. IC₅₀ values shown by gold and silver nanoparticles (44.1 ± 0.82 and 57.92 ± 1.33 μg/mL) reflected their high free radical scavenging potential. The synthesized gold and silver nanoparticles revealed their potency to inhibit pathogenic microorganisms Bacillus pumilus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Aspergillus niger, and Penicillium chrysogenum. Anthropogenic pollutants rhodamine B and methyl orange were effectively degraded from aquatic environment and waste water sewages of dye industries using the prepared nanocatalysts. The catalytic capacities of the synthesized nanoparticles were also exploited in the reduction of 4-nitrophenol.

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Antioxidant defense gene analysis in <Emphasis Type="Italic">Brassica oleracea</Emphasis> and <Emphasis Type="Italic">Trifolium repens</Emphasis> exposed to Cd and/or Pb

This study focused on the expression analysis of antioxidant defense genes in Brassica oleracea and in Trifolium repens. Plants were exposed for 3, 10, and 56 days in microcosms to a field-collected suburban soil spiked by low concentrations of cadmium and/or lead. In both species, metal accumulations and expression levels of genes encoding proteins involved and/or related to antioxidant defense systems (glutathione transferases, peroxidases, catalases, metallothioneins) were quantified in leaves in order to better understand the detoxification processes involved following exposure to metals. It appeared that strongest gene expression variations in T. repens were observed when plants are exposed to Cd (metallothionein and ascorbate peroxidase upregulations) whereas strongest variations in B. oleracea were observed in case of Cd/Pb co-exposures (metallothionein, glutathione transferase, and peroxidase upregulations). Results also suggest that there is a benefit to use complementary species in order to better apprehend the biological effects in ecotoxicology.     

Tolerance of Japanese knotweed <Emphasis Type="Italic">s</Emphasis>.<Emphasis Type="Italic">l</Emphasis>. to soil artificial polymetallic pollution: early metabolic responses and performance during vegetative multiplication

The expansion of invasive Japanese knotweed s.l. is of particular concern because of its aptitudes to rapidly colonize diverse environments, especially anthropized habitats generally characterized by their pollution with heavy metals. Whether the presence of heavy metals impacts the performance traits of this plant is a central question to better understand its invasive properties, though no controlled approach to assess these effects was yet reported. In this aim, we undertook greenhouse experiments where rhizome fragments of Japanese knotweed s.l. (Fallopia japonica and Fallopia × bohemica) were grown during 1 and 3 months, in a soil pot artificially polluted or not with heavy metals added in mixture (Cd, Cr, Pb, Zn). Our results showed that (i) the presence of heavy metals delayed rhizome regeneration and induced lowered plant part weights but did not affect plant height after 3 months; (ii) the effect of metals on the metabolic profiles of belowground part extracts was only detectable after 1 month and not after 3 months of growth, though it was possible to highlight the effect of metals independently of time and genotype for root extracts, and torosachrysone seemed to be the most induced compound; and (iii) the hybrid genotype tested was able to accumulate relatively high concentrations of metals, over or close to the highest reported ones for this plant for Cr, Cd and Zn, whereas Pb was not accumulated. These findings evidence that the presence of heavy metals in soil has a low impact on Fallopia sp. overall performance traits during rhizome regeneration, and has a rather stimulating effect on plant growth depending on pollution level.     

Phenological development stages variation versus mercury tolerance,accumulation, and allocation in salt marsh macrophytes <Emphasis Type="Italic">Triglochin maritima</Emphasis> and <Emphasis Type="Italic">Scirpus maritimus</Emphasis> prevalent in Ria de Aveiro coastal lagoon (Portugal)

Efficient and sustainable management of rapidly mounting environmental issues has been the focus of current intensive research. The present study aimed to investigate the impact of plant phenological development stage variation on mercury (Hg) tolerance, accumulation, and allocation in two salt marsh macrophytes Triglochin maritima and Scirpus maritimus prevalent in historically Hg-contaminated Ria de Aveiro coastal lagoon (Portugal). Both plant samples and the sediments vegetated by monospecific stands of T. maritima and S. maritimus were collected from reference (R) and sites with moderate (M) and high (H) Hg contamination in Laranjo bay within Ria de Aveiro lagoon. Hg tolerance, uptake, and allocation in T. maritima and S. maritimus, physico-chemical traits (pH, redox potential, and organic matter content) and Hg concentrations in sediments vegetated by these species were impacted differentially by phenological development stages variation irrespective of the Hg contamination level. In T. maritima, Hg concentration increased with increase in Hg contamination gradient where root displayed significantly higher Hg followed by rhizome and leaf maximally at H. However, in S. maritimus, the highest Hg concentration was perceptible in rhizome followed by root maximally at M. Between the two studied plant species, S. maritimus displayed higher Hg tolerance index (depicted by higher plant dry mass allocated to reproductive stage) and higher available Hg at M (during all growth stages) and H (during senescent stage) when compared to T. maritimus. Both plant species proved to be Hg excluder (low root/rhizome–leaf Hg translocation). Additionally, T. maritima also acted as Hg stabilizer while, S. maritimus as Hg accumulator. It can be inferred from the study that (a) the plant phenological development stage variations significantly influenced plant Hg sensitivity by impacting sediment chemistry, plant growth (in terms of plant dry mass), Hg accumulation, and its subsequent allocation capacity, contingent to Hg contamination gradient; (b) S. maritimus accumulated higher Hg but restricted its translocation to above-ground part using exclusion process at both M and H due to its accelerated growth during Hg-tolerant reproductive/metabolically active phenological development stage greater than its counterpart T. maritima; and (c) the studied salt marsh plants although hailed from the same C3 and monocot group did not necessarily display similar phenotypic plasticity and behavior towards Hg-contaminated scenario during their life cycle.     

Inhibition of residual <Emphasis Type="Italic">n</Emphasis>-hexane in anaerobic digestion of lipid-extracted microalgal wastes and microbial community shift

Converting lipid-extracted microalgal wastes to methane (CH₄) via anaerobic digestion (AD) has the potential to make microalgae-based biodiesel platform more sustainable. However, it is apparent that remaining n-hexane (C₆H₁₄) from lipid extraction could inhibit metabolic pathway of methanogens. To test an inhibitory influence of residual n-hexane, this study conducted a series of batch AD by mixing lipid-extracted Chlorella vulgaris with a wide range of n-hexane concentration (～10 g chemical oxygen demand (COD)/L). Experimental results show that the inhibition of n-hexane on CH₄ yield was negligible up to 2 g COD/L and inhibition to methanogenesis became significant when it was higher than 4 g COD/L based on quantitative mass balance. Inhibition threshold was about 4 g COD/L of n-hexane. Analytical result of microbial community profile revealed that dominance of alkane-degrading sulfate-reducing bacteria (SRB) and syntrophic bacteria increased, while that of methanogens sharply dropped as n-hexane concentration increased. These findings offer a useful guideline of threshold n-hexane concentration and microbial community shift for the AD of lipid-extracted microalgal wastes.     

Isolation and characterization of <Emphasis Type="Italic">Bradyrhizobium</Emphasis> sp. SR1 degrading two β-triketone herbicides

In this study, a bacterial strain able to use sulcotrione, a β-triketone herbicide, as sole source of carbon and energy was isolated from soil samples previously treated with this herbicide. Phylogenetic study based on16S rRNA gene sequence showed that the isolate has 100 % of similarity with several Bradyrhizobium and was accordingly designated as Bradyrhizobium sp. SR1. Plasmid profiling revealed the presence of a large plasmid (>50 kb) in SR1 not cured under nonselective conditions. Its transfer to Escherichia coli by electroporation failed to induce β-triketone degrading capacity, suggesting that degrading genes possibly located on this plasmid cannot be expressed in E. coli or that they are not plasmid borne. The evaluation of the SR1 ability to degrade various synthetic (mesotrione and tembotrione) and natural (leptospermone) triketones showed that this strain was also able to degrade mesotrione. Although SR1 was able to entirely dissipate both herbicides, degradation rate of sulcotrione was ten times higher than that of mesotrione, showing a greater affinity of degrading-enzyme system to sulcotrione. Degradation pathway of sulcotrione involved the formation of 2-chloro-4-mesylbenzoic acid (CMBA), previously identified in sulcotrione degradation, and of a new metabolite identified as hydroxy-sulcotrione. Mesotrione degradation pathway leads to the accumulation of 4-methylsulfonyl-2-nitrobenzoic acid (MNBA) and 2-amino-4 methylsulfonylbenzoic acid (AMBA), two well-known metabolites of this herbicide. Along with the dissipation of β-triketones, one could observe the decrease in 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibition, indicating that toxicity was due to parent molecules, and not to the formed metabolites. This is the first report of the isolation of bacterial strain able to transform two β-triketones.     

Evaluation of the giant reed (<Emphasis Type="Italic">Arundo donax</Emphasis>) in horizontal subsurface flow wetlands for the treatment of recirculating aquaculture system effluent

Introduction

Two emergent macrophytes, Arundo donax and Phragmites australis, were established in experimental subsurface flow, gravel-based constructed wetlands (CWs) receiving untreated recirculating aquaculture system wastewater.

Materials and methods

The hydraulic loading rate was 3.75 cm day^?1. Many of the monitored water quality parameters (biological oxygen demand [BOD], total suspended solids [TSS], total phosphorus [TP], total nitrogen [TN], total ammoniacal nitrogen [TAN], nitrate nitrogen [NO₃], and Escherichia coli) were removed efficiently by the CWs, to the extent that the CW effluent was suitable for use on human food crops grown for raw produce consumption under Victorian state regulations and also suitable for reuse within aquaculture systems.

Results and discussion

The BOD, TSS, TP, TN, TAN, and E. coli removal in the A. donax and P. australis beds was 94%, 67%, 96%, 97%, 99.6%, and effectively 100% and 95%, 87%, 95%, 98%, 99.7%, and effectively 100%, respectively, with no significant difference (p?>?0.007) in performance between the A. donax and P. australis CWs. In this study, as expected, the aboveground yield of A. donax top growth (stems + leaves) (15.0?±?3.4 kg wet weight) was considerably more than the P. australis beds (7.4?±?2.8 kg wet weight). The standing crop produced in this short (14-week) trial equates to an estimated 125 and 77 t ?ha^?1 year^?1 biomass (dry weight) for A. donax and P. australis, respectively (assuming that plant growth is similar across a 250-day (September–April) growing season and a single-cut, annual harvest).

Conclusion

The similarity of the performance of the A. donax- and P. australis-planted beds indicates that either may be used in horizontal subsurface flow wetlands treating aquaculture wastewater, although the planting of A. donax provides additional opportunities for secondary income streams through utilization of the energy-rich biomass produced.

     

Effects of realistic concentrations of TiO<Subscript>2</Subscript> and ZnO nanoparticles in <Emphasis Type="Italic">Prochilodus lineatus</Emphasis> juvenile fish

The impact of nanoparticles on fish health is still a matter of debate, since nanotechnology is quite recent. In this study, freshwater benthonic juvenile fish Prochilodus lineatus were exposed through water to three concentrations of TiO₂ (0.1, 1, and 10 μg l^?1) and ZnO (7, 70, and 700 μg l^?1) nanoparticles, as well as to a mixture of both (TiO₂ 1 μg l^?1?+?ZnO 70 μg l^?1) for 5 and 30 days. Nanoparticle characterization revealed an increase of aggregate size in the function of concentration, but suspensions were generally stable. Fish mortality was high at subchronic exposure to 70 and 700 μg l^?1 of ZnO. Nanoparticle exposure led to decreased acetylcholinesterase activity either in the muscle or in the brain, depending on particle composition (muscle—TiO₂ 10 μg l^?1; brain—ZnO 7 and 700 μg l^?1), and protein oxidative damage increased in the brain (ZnO 70 μg l^?1) and gills (ZnO 70 μg l^?1 and mixture) but not in the liver. Exposed fish had more frequent alterations in the liver (necrosis, vascular congestion, leukocyte infiltration, and basophilic foci) and gills (hyperplasia and epithelial damages, e.g., epithelial disorganization and epithelial loss) than the control fish. Thus, predicted concentrations of TiO₂ and ZnO nanoparticles caused detectable effects on P. lineatus that may have important consequences to fish health. But, these effects are much more subtle than those usually reported in the scientific literature for high concentrations or doses of metal nanoparticles.     

Measurements of β and α hexachlorocyclohexane in <Emphasis Type="Italic">Juglans regia</Emphasis> and <Emphasis Type="Italic">Prunus spinosa</Emphasis> trees in a contaminated area,central Italy

Vegetables play an important role in the human diet, and the transfer of toxic contaminants from the soil to plants has been little studied for most tree species and their edible portions. In an area affected by hexachlorocyclohexane (HCH) contamination, in the Sacco River Valley (central Italy), measurements of β- and α-HCH isomers were made on different parts of two tree species: Juglans regia and Prunus spinosa. Concentrations were analysed in roots, branches, leaves, fruits, and seeds. A spatial evaluation of the results highlighted an inverse association of contamination with distance from the river, which is the main route of transport in the environment. Results in J. regia showed decreasing values in this order: branches > leaves > husks > nutmeat. Results in P. spinosa showed decreasing values in the following order: branches > leaves > fruits. In J. regia, nutmeat values were all below limit of detection (LOD, 0.0005 mg/kg), except in one case in which a very low concentration of β-HCH was found (0.006 mg/Kg), compliant with maximum residue limits (MRLs). The ability of J. regia to store large quantities of β-HCH in wooden and leafy parts but not in edible kernels makes this plant a potential and precious tool in remediation and economical reconversion of polluted areas. It is also valuable for food and wood manufacturing.     

Toxicity of Cu (II) to the green alga <Emphasis Type="Italic">Chlorella vulgaris</Emphasis>: a perspective of photosynthesis and oxidant stress

The toxic effects of Cu (II) on the freshwater green algae Chlorella vulgaris and its chloroplast were investigated by detecting the responses of photosynthesis and oxidant stress. The results showed that Cu (II) arrested the growth of C. vulgaris and presented in a concentration- and time-dependent trend and the SRichards 2 model fitted the inhibition curve best. The chlorophyll fluorescence parameters, including qP, Y (II), ETR, F _v /F _m , and F _v /F ₀, were stimulated at low concentration of Cu (II) but declined at high concentration, indicating the photosystem II (PSII) of C. vulgaris was destroyed by Cu (II). The chloroplasts were extracted, and the Hill reaction activity (HRA) of chloroplast was significantly decreased with the increasing Cu (II) concentration under both illuminating and dark condition, and faster decline speed was observed under dark condition. Activities of superoxide dismutase (SOD) and catalase (CAT) and malondialdehyde (MDA) content were also significantly decreased at high concentration Cu (II), companied with a large number of reactive oxygen species (ROS) production. All these results indicated a severe oxidative stress on algal cells occurred as well as the effect on photosynthesis, thus inhibiting the growth of algae, which providing sights to evaluate the phytotoxicity of Cu (II).     

Interactions between sewage sludge-amended soil and earthworms—comparison between <Emphasis Type="Italic">Eisenia fetida</Emphasis> and <Emphasis Type="Italic">Eisenia andrei</Emphasis> composting species

Vermicomposting is an eco-friendly technology, where earthworms are introduced in the waste, inter alia sewage sludge, to cooperate with microorganisms and enhance decomposition of organic matter. The main aims of the present study was to determine the influence of two different earthworm species, Eisenia fetida and Eisenia andrei, on the changes of selected metallic trace elements content in substratum during vermicomposting process using three different sewage sludge mainly differentiated by their metal contents. Final vermicompost has shown a slight reduction in Cd, Cu, Ni, and Pb, while the Zn concentration tends to increase. Accumulation of particular heavy metals in earthworms’ bodies was assessed. Both species revealed high tendency to accumulate Cd and Zn, but not Cu, Ni, and Pb, but E. andrei has higher capabilities to accumulate some metals. Riboflavin content, which content varies depending on metal pollution in several earthworms species, was measured supravitaly in extruded coelomocytes. Riboflavin content decreased slightly during the first 6 weeks of exposure and subsequently restored till the end of the 9-week experiment. Selected agronomic parameters have also been measured in the final product (vermicompost) to assess the influence of earthworms on substratum.     

Copper bioaccumulation,photosystem II functioning,and oxidative stress in the seagrass <Emphasis Type="Italic">Cymodocea nodosa</Emphasis> exposed to copper oxide nanoparticles

Photosynthetic activity, oxidative stress, and Cu bioaccumulation in the seagrass Cymodocea nodosa were assessed 4, 12, 24, 48, and 72 h after exposure to two copper oxide nanoparticle (CuO NP) concentrations (5 and 10 mg L^?1). CuO NPs were characterized by scanning electron microscopy (SEM) and dynamic light scattering measurements (DLS). Chlorophyll fluorescence analysis was applied to detect photosystem II (PSII) functionality, while the Cu accumulation kinetics into the leaf blades was fitted to the Michaelis-Menten equation. The uptake kinetics was rapid during the first 4 h of exposure and reached an equilibrium state after 10 h exposure to 10 mg L^?1 and after 27 h to 5 mg L^?1 CuO NPs. As a result, 4-h treatment with 5 mg L^?1 CuO NPs, decreased the quantum yield of PS II photochemistry (Φ _PSΙΙ ) with a parallel increase in the regulated non-photochemical energy loss in PSII (Φ _NPQ ). However, the photoprotective dissipation of excess absorbed light energy as heat, through the process of non-photochemical quenching (NPQ), did not maintain the same fraction of open reaction centers (q _p ) as in control plants. This reduced number of open reaction centers resulted in a significant increase of H₂O₂ production in the leaf veins serving possibly as an antioxidant defense signal. Twenty-four-hour treatment had no significant effect on Φ _PSΙΙ and q _p compared to controls. However, 24 h exposure to 5 mg L^?1 CuO NPs increased the quantum yield of non-regulated energy loss in PSII (Φ _NO ), and thus the formation of singlet oxygen (¹O₂) via the triplet state of chlorophyll, possible because the uptake kinetics had not yet reached the equilibrium state as did 10 mg L^?1. Longer-duration treatment (48 and 72 h) had less effect on the allocation of absorbed light energy at PSII and the fraction of open reaction centers, compared to 4-h treatment, suggesting the function of a stress defense mechanism. The response of C. nodosa leaves to CuO NPs fits the “Threshold for Tolerance Model” with a threshold time (more than 4 h) required for induction of a stress defense mechanism, through H₂O₂ production.     

Biodegradation of toluene vapor in coir based upflow packed bed reactor by <Emphasis Type="Italic">Trichoderma asperellum</Emphasis> isolate

In the present study, a new biofiltration system involving a selective microbial strain isolated from aerated municipal sewage water attached with coir as packing material was developed for toluene degradation. The selected fungal isolate was identified as Trichoderma asperellum by 16S ribosomal RNA (16S rRNA) sequencing method, and pylogenetic tree was constructed using BLASTn search. Effect of various factors on growth and toluene degradation by newly isolated T. asperellum was studied in batch studies, and the optimum conditions were found to be pH 7.0, temperature 30 °C, and initial toluene concentration 1.5 (v/v)%. Continuous removal of gaseous toluene was monitored in upflow packed bed reactor (UFPBR) using T. asperellum. Effect of various parameters like column height, flow rate, and the inlet toluene concentration were studied to evaluate the performance of the biofilter. The maximum elimination capacity (257 g m^?3 h^?1) was obtained with the packing height of 100 cm with the empty bed residence time of 5 min. Under these optimum conditions, the T. asperellum showed better toluene removal efficiency. Kinetic models have been developed for toluene degradation by T. asperellum using macrokinetic approach of the plug flow model incorporated with Monod model.