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Resultados 4001-4010 de 4,924
First occurrence and composition assessment of microplastics in native mussels collected from coastal and offshore areas of the northern and central Adriatic Sea
2019
Gomiero, Alessio | Strafella, Pierluigi | Øysæd, Kjell Birger | Fabi, Gianna
In recent years, the occurrence of microplastics in the aquatic environment has gathered increasing scientific interest. Several studies have shown that the ingestion of microplastics may negatively influence the physiology of marine organisms having different feeding strategies, particularly in those species which cannot discriminate between food sources. Recent studies highlighted the potential for such particles to accumulate in the food web, posing risks to human health via the consumption of seafood. Furthermore, early findings also indicated the role of microplastics as vectors of chemical pollutants either used as additives during synthesis of the plastics or adsorbed directly from seawater, i.e., PAHs, PCB, and surfactants. Despite the importance of microplastics in adsorption and transport of hydrophobic pollutants, little is known about their distribution and accumulation in marine food webs, or their direct and indirect harmful effects. The Adriatic Sea represents a semi-enclosed basin with a low water recirculation rate and high anthropogenic pressures associated with unsustainable fishing and inputs of contaminants. The body burden, accumulation rates, polymer composition, and recurring morphotypes of microplastics in native blue mussels (M. galloprovincialis) were examined. Organisms collected offshore were compared to those collected in coastal areas. Microplastics were recovered from the soft tissues of all analyzed mussels. Coastal organisms showed a load of 1.06–1.33 fragments g⁻¹ (wet weight) and 0.62–0.63 fibers g⁻¹ (wet weight) while offshore organisms showed an accumulation of 0.65–0.66 fragments g⁻¹ (wet weight) and 0.24–0.35 fibers g⁻¹ (wet weight). The size class distribution revealed a marked prevalence of smaller particles (20 μm to 40 μm range) and the most recurring polymer type in analyzed organisms was PE followed by PP, PET, and equal amounts of PS, PLY, and PVC. A significant site-, time-, and oceanographic-related distribution trend was observed. Based on the findings presented here, there is a clear need to implement a seafood safety monitoring program to better understand actual human health–related risks.
Mostrar más [+] Menos [-]Synthesis of magnetite-based nanocomposites for effective removal of brilliant green dye from wastewater
2019
Imran, Muhammad | Islam, Azhar Ul | Tariq, Muhammad Adnan | Siddique, Muhammad Hussnain | Shah, Noor Samad | Khan, Zia Ul Haq | Amjad, Muhammad | Din, Salah Ud | Shah, Ghulam Mustafa | Naeem, Muhammad Asif | Nadeem, Muhammad | Nawaz, Muhammad | Rizwan, Muhammad
The present study aims at evaluating the batch scale potential of cotton shell powder (CSP), Moringa oleifera leaves (ML), and magnetite-assisted composites of Moringa oleifera leaves (MLMC) and cotton shell powder (CSPMC) for the removal of brilliant green dye (BG) from synthetic wastewater. This is the first attempt to combine biosorbents with nanoparticles (NPs) for the removal of BG. The surface properties of ML, CSP, and their composites were characterized with Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX). The impact of dosage of the adsorbents (1–4 g/L), initial concentrations of BG (20–320 mg/L), pH (6–12), and contact time (15–180 min) on BG removal was evaluated. The BG removal was in order of CSPMC > MLMC > CSP > ML (98.8–86.6% > 98.2–82.0% > 92.3–70.7% > 89.0–57.4%) at optimum dosage (2 g/L) and pH (8). Moreover, maximum adsorption (252.17 mg/g) was obtained with CSPMC. The experimental results showed better fit with Freundlich adsorption isotherm model and kinetic data revealed that sorption followed pseudo-second-order kinetic model. The values of Gibbs free energy and mean free energy of sorption showed that physical adsorption was involved in the removal of BG. FTIR results confirmed that –O-H, –C-OH, =C-H, –C-H, =–CH₃, HC ≡ CH, C=C, –C=O, –C-N, and –C-O-C– groups were involved in the removal of BG. The results revealed that application of low-cost biosorbents combined with NPs is very effective and promising for the removal of textile dyes from wastewater.
Mostrar más [+] Menos [-]Cu(II) removal using green adsorbents: kinetic modeling and plant scale-up design
2019
Banerjee, Munmun | Basu, Ranjan Kumar | Das, Sudip Kumar
Cu(II) adsorption in continuous column using green adsorbents like peanut and almond shell was investigated. Fourier transform infrared (FTIR) spectroscopy, Brunaer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), and Point of Zero charge (pHₚzc) determination have been used for characterization of the adsorbents. Experiments were conducted at various operating conditions to calculate the adsorption capacity of the adsorbents. Adsorption studies signify that both the adsorbents have good adsorptive capacity for Cu(II) ion. Equilibrium of adsorption was described using Langmuir isotherm and the highest qₘₐₓ value for both the adsorbent were obtained at an operating condition of 20 ml/min flow rate, 15 mg/L influent Cu(II) concentration, and 7 cm bed depth. Regeneration of both the adsorbents suggests that these adsorbents can be used several times for Cu(II) removal. Seven different kinetic models were tested among which the modified dose response model was fitted well for peanut shell and the Thomas model was fitted well for almond shell. These fitted models were further used for scale-up design. Regeneration studies show that peanut shell and almond shell are useful up to the fifth adsorption cycle. Application of these adsorbents with industrial effluent was also reported. This study reveals that peanut and almond shells can be used for Cu(II) removal for industrial wastewater.
Mostrar más [+] Menos [-]Acute triflumuron exposure induces oxidative stress responses in liver and kidney of Balb/C mice
2019
Timoumi, Rim | Amara, Ines | Neffati, Fadwa | Najjar, Mohamed Fadhel | El Golli-Bennour, Emna | Bacha, Hassen | Abid-Essefi, Salwa
Triflumuron (TFM) is one of the most widely used insecticides over the world. It is a benzoylphenyl urea that belongs to the class of insect growth regulators. This insecticide acts by inhibiting insect’s chitin synthesis and by consequences, making insect more susceptible to pathogens and malformations. TFM effects have been reported in mammalians and crops. However, studies that reveal its toxicity mechanisms are limited. In this line, the current study aimed to determine the implication of oxidative stress in the toxicity induced by TFM and particularly in the perturbation of biochemical parameters in male Balb/C mice. Male Balb/C mice were divided into three groups receiving TFM at doses of 250, 350, and 500 mg/kg bw respectively. The occurrence of oxidative stress in both kidney and liver tissues was monitored by measuring of oxidative stress markers. TFM caused an increase as protein carbonyls generation, malondialdehyde induction (MDA) and catalase (CAT), superoxide dismutase (SOD), glutathion peroxidase (Gpx), as well as glutathion S transferase (GST) activities. In the same conditions, we have evaluated the effect of TFM treatment on biochemical parameters. In response to the three TFM doses, we showed significant dose dependent inductions in all tested oxidative stress markers. However, TFM caused an increase in the liver enzyme activities as aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), g-glutamyltranspeptidase (GTT), and total bilirubin (BILT) in a dose-dependent manner. Equally, renal markers as urea, uric acid, albumin, and creatinine were increased in the same manner. We can conclude that oxidative damage seems to be a key determinant of TFM-induced toxicity in both liver and kidney of male Balb/C mice. Moreover, the oxidative stress is more pronounced in the liver than in the kidney. Thus, TFM may be considered as a hepatotoxic insecticide.
Mostrar más [+] Menos [-]Distribution and emission characteristics of filterable and condensable particulate matter before and after a low-low temperature electrostatic precipitator
2019
Li, Xiaodong | Zhou, Chenyang | Li, Jingwei | Lu, Shengyong | Yan, Jianhua
The low-low temperature electrostatic precipitator (LLT-ESP), a combination of a traditional temperature electrostatic precipitator (ESP) and a non-leakage media gas-gas exchange (MGGH), could reduce the inlet flue gas temperature below the dew point and improved the performance of the ESP. Particulate matter (PM) from the stationary sources contains filterable particulate matter (FPM) and condensable particulate matter (CPM). In this study, coal with a high ash content (coal-HA) was burned, and the emission characteristics and removal efficiencies of the particulate matter in an LLT-ESP were investigated. The standards used to test filterable and condensable PM were ISO standard 23210-2009 and U.S. EPA Method 202, respectively. The LLT-ESP was efficient in removing filterable PM, with a total filterable PM removal efficiency as high as 99.6%. The removal efficiency of filterable PM increased with increasing particulate size and decreasing imported flue gas temperature. The LLT-ESP also provided excellent removal of condensable PM with a condensable PM removal efficiency exceeding 77%. Upstream of the LLT-ESP, the concentrations of filterable PM were much higher than those of condensable PM. Downstream of the LLT-ESP, the relationship between the quantities of condensable and filterable PM reversed. To reduce the emissions of PM from coal-fired power plants, more attention should be paid to controlling condensable PM. The temperature of the flue gas upstream of the LLT-ESP played an important role in eliminating condensable PM. At lower imported flue gas temperature operation conditions, the removal efficiency of the LLT-ESP for the condensable PM and the escaping mass concentration of condensable PM increased. Among the organic fraction of the condensable PM, hydrocarbons and esters were dominant. Meanwhile, SO₄²⁻ was the primary component, followed by Cl⁻ in anions. Na⁺, Ca²⁺, and Fe³⁺ were the main components in metal ions. Particles with diameters ≥ 10 μm, which contained most of the Si and Al, were dominant in the fly ash collected from sections 1 and 2 of the LLT-ESP. The main particles in sections 3 and 4 were PM₁₀, which contained the highest concentrations of Ca and Fe.
Mostrar más [+] Menos [-]Historical accumulation of potentially toxic trace elements resulting from mining activities in estuarine salt marshes sediments of the Asturias coastline (northern Spain)
2019
Garcia-Ordiales, Efrén | Cienfuegos, Pablo | Roqueñí, Nieves | Covelli, Stefano | Flor-Blanco, German | Fontolan, Giorgio | Loredo, Jorge
The extensive extraction activity of mercury ores in Asturias (northwest Spain), also rich in As and Sb, has impacted the Nalón river estuary. The objective of this research was to assess the historical evolution of As-Hg-Sb accumulation in the salt marsh sediments of this area. For this purpose, sediment cores were collected from two different salt marshes (eastern and western river banks) in the estuarine environment to evaluate the degree of anthropogenic enrichment and the geochronology of As-Hg-Sb accumulation. Core subsampling was performed by cutting 2-cm-thick slices of sediments. The subsamples were then analysed for several physical and chemical parameters. Sedimentation rate was assessed by measuring short-lived radionuclides (excess ²¹⁰Pb and ¹³⁷Cs). Pre-mining levels of As-Hg-Sb were observed at core depths below 50 cm. In the less extended salt marsh (eastern river bank), maximum As-Hg-Sb concentrations of 87.48, 3.66, and 5.75 μg·g⁻¹, respectively, were found at the core top as a consequence of long-term mining activity in the area. The vertical distribution of As-Hg-Sb was influenced by the single-point contamination sources, whereas grain-size variability and diagenetic remobilisation did not seem affected. Geochronological measurements showed that the depositional fluxes of As-Hg-Sb were influenced by anthropogenic input after 1900, when mining activity in the area was most intense. Hg mining ceased in 1969; however, the corresponding core profiles did not show a drastic decreasing trend in element fluxes, implying that the river drainage basin retains some “memory” of contamination which affects riverine sediments. A preliminary gross estimation of total As-Hg-Sb “trapped” in the Nalón river salt marsh sediments amounted to approximately 18.7, 1.0, and 0.7 t, respectively. These morphological structures suffer erosive processes, thus representing a potential source of these elements associated with sediments; consequently, management conservation and monitoring of salt marshes should be taken into consideration from this environmental point of view.
Mostrar más [+] Menos [-]Steady-state modeling of the biodegradation performance of a multistage moving bed biofilm reactor (MBBR) used for on-site greywater treatment
2019
Masmoudi Jabri, Khaoula | Fiedler, Thorsten | Saidi, Assia | Nolde, Erwin | Ogurek, Michael | Geissen, S.-U. (Sven-Uwe) | Bousselmi, Latifa
In this study, the Activated Sludge Model No. 3 (ASM3) was applied for the simulation of the removal of organics and nitrogen in a multistage moving bed biofilm reactor (MBBR) used for biological greywater treatment. The data related to the characterization of the greywater were collected over a period of 5 months to be investigated in the model. The reactor showed a high performance for the removal of chemical oxygen demand (COD), dissolved organic carbon (DOC), biological oxygen demand (BOD₅), ammonia (NH₄-N), and total nitrogen (TN) with a removal efficiency of 93%, 80.7%, 99%, 89%, and 77%, respectively. The results of modeling showed a good correlation between simulated and experimental concentrations of COD issued from different reactors of the MBBR system. The adaptability of the ASM3 model to fit other parameters such as TN, NH₄-N, total suspended solids (TSS), and the dissolved oxygen (DO) was also investigated for two selected reactors: reactor (R1) and the reactor (R5). The simulation results showed an acceptable correlation regarding the evolution of the investigated parameters in R1 and R5 and in the effluent except for total nitrogen TN. The adjustment of the stoichiometric parameters led to a satisfactory simulation of TN concentrations.
Mostrar más [+] Menos [-]Comparative toxicity of a food additive TiO2, a bulk TiO2, and a nano-sized P25 to a model organism the nematode C. elegans
2019
Ma, Hongbo | Lenz, Kade A. | Gao, Xianfeng | Li, Shibin | Wallis, Lindsay K.
To help fill the knowledge gap regarding the potential human health impacts of food pigment TiO₂, a comparative toxicity study was performed on a food-grade TiO₂ (f-TiO₂), a bulk TiO₂ (b-TiO₂), and a nano-sized TiO₂ (Degussa P25), and in the nematode Caenorhabditis elegans. Acute phototoxicity and chronic toxicity effects including reproduction, lifespan, and vulval integrity were evaluated. The f-TiO₂, b-TiO₂, and P25 had a primary particle size (size range) of 149 (53–308) nm, 129 (64–259) nm, and 26 (11–52) nm, respectively. P25 showed the greatest phototoxicity with a 24-h LC50 of 6.0 mg/L (95% CI 5.95, 6.3), followed by the f-TiO₂ (LC50 = 6.55 mg/L (95% CI 6.35, 6.75)), and b-TiO₂ was the least toxic. All three TiO₂ (1–10 mg/L) induced concentration-dependent effects on the worm’s reproduction, with a reduction in brood size by 8.5 to 34%. They all caused a reduction of worm lifespan, accompanied by an increased frequency of age-associated vulval integrity defects (Avid). The impact on lifespan and Avid phenotype was more notable for P25 than the f-TiO₂ or b-TiO₂. Ingestion and accumulation of TiO₂ particles in the worm intestine was observed for all three materials by light microscopy. These findings demonstrate that the food pigment TiO₂ induces toxicity effects in the worm and further studies are needed to elucidate the human health implication of such toxicities.
Mostrar más [+] Menos [-]Do Amazon turtles exposed to environmental concentrations of the antineoplastic drug cyclophosphamide present mutagenic damages? If so, would such damages be reversible?
2019
Mesak, Carlos | Montalvão, Mateus Flores | Paixão, Caroliny Fátima Chaves | Mendes, Bruna de Oliveira | Araújo, Amanda Pereira da Costa | Quintão, Thales Chagas | Malafaia, Guilherme
Antineoplastic drugs (AD) have been increasingly used, but the disposal of their wastes in the environment via hospital effluent and domestic sewage has emerged as an environmental issue. The current risks posed to these animals and effects of pollutants on the reptiles’ population level remain unknown due to lack of studies on the topic. The aim of the present study was to evaluate the mutagenicity of neonate Podocnemis expansa exposed to environmental concentrations (EC) of cyclophosphamide (Cyc). The adopted doses were EC-I 0.2 μg/L and EC-II 0.5 μg/L Cyc. These doses correspond to 1/10 and ¼ of concentrations previously identified in hospital effluents. Turtles exposed to the CyC recorded larger total number of erythrocyte nuclear abnormalities than the ones in the control group after 48-h exposure. The total number of abnormalities for both groups (EC-I and EC-II) 96 h after the experiment had started was statistically similar to that of animals exposed to high Cyc concentration (positive control 5 × 10⁴ μg/L). This outcome confirms the mutagenic potential of Cyc, even at low concentrations. On the other hand, when the animals were taken to a pollutant-free environment, their mutagenic damages disappeared after 240 h. After such period, their total of abnormalities matched the basal levels recorded for the control group. Therefore, our study is the first evidence of AD mutagenicity in reptiles, even at EC and short-term exposure, as well as of turtles’ recovery capability after the exposure to Cyc.
Mostrar más [+] Menos [-]A new measurement tool to consider for airborne pollutants evaluations using lichens
2019
Catán, Soledad Perez | Bubach, Debora | Messuti, María Inés
An important factor affecting acquisition of pollution elements could be the lichen growth form. The Brunauer–Emmett–Teller theory approach has been used to determinate the specific area surface (BET-area) of solids by gas multilayer adsorption. Taking this standard method as a new tool, we measure the specific thallus area in foliose and fruticose lichens to evaluated area/volume relation for bioaccumulation prospects. Some preliminary results of elemental contents such as REEs (La, Sc, Sr) and pollutants (Cd, Co, Pb) were also measured to support the importance to use for the analysis of these thallus attributes.
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