خيارات البحث
النتائج 1961 - 1970 من 6,558
Use of iron mining tailings from dams for carbon nanotubes synthesis in fluidized bed for 17α-ethinylestradiol removal النص الكامل
2020
Silva, Rayane Cristian Ferreira | Ardisson, José Domingos | Cotta, Alexandre Alberto Chaves | Araujo, Maria Helena | Teixeira, Ana Paula de Carvalho
This work reports the use of an iron ore tailings from waste dam as a catalyst and support for carbon nanotubes synthesis and their application in the adsorption of the 17α-ethinylestradiol hormone. The synthesis was carried out by Chemical Vapor Deposition (CVD) in a Fluidized Bed system using: ethylene at temperatures of 500, 600 and 700 °C, and acetonitrile at 500, 600, 700, 800 and 900 °C. The transmission electron microscopy (TEM) results showed that the two higher temperatures in each case favored the formation of nanostructures like carbon nanotubes (CNTs), with good yields. The ethylene source generated classic tubular structures of multiple walls. On the other hand, acetonitrile provided the formation of tubes with less organization, known as bamboo like. This morphology was caused by the insertion of nitrogen into the graphite structure (doping), which originates from the carbon source. The adsorptive capacity of the materials for 17α-Ethinylestradiol removal ranging from 9.2 mg g⁻¹ to 22.3 mg g⁻¹. The kinetic and adsorption isotherm studies were also performed for the systems. As for kinetics, all of them presented pseudo-second order behavior. In relation to the type of isotherm, the systems showed Freundlich behavior, that is, the adsorption occurs in multiple layers. Finally, it was concluded that the use of an iron ore tail as a catalyst in the production of CNTs by CVD is feasible. The materials synthesized still had good adsorptive capacity for an emerging contaminant, thus this study allowed the investigation of two environmental problems.
اظهر المزيد [+] اقل [-]Interactive effects of arsenic and antimony on Ipomoea aquatica growth and bioaccumulation in co-contaminated soil النص الكامل
2020
Egodawatta, Lakmini P. | Holland, Aleicia | Koppel, Darren | Jolley, Dianne F.
Antimony (Sb) is an emerging contaminant and until recently it was assumed to behave in a similar way to arsenic (As). Arsenic and Sb often co-occur in contaminated sites, yet most investigations consider their toxicity to plants singly. More research is needed to understand the interactions between As and Sb in soils and plants. This study investigated the interactive effect of As and Sb in terms of soil bioavailability, plant toxicity and bioaccumulation on the commercially important agricultural plant, water spinach (Ipomoea aquatica) using a pot experiment. Plants were exposed to As and Sb individually (As ₍ᵢₙdᵢᵥᵢdᵤₐₗ₎, Sb ₍ᵢₙdᵢᵥᵢdᵤₐₗ₎) and as a mixture (As + Sb ₍cₒₘbᵢₙₑd₎) at different concentrations. Plant growth was measured using shoot and root dry mass, length and chlorophyll a content of leaves. At the end of the bioassay, bioavailable metalloids were extracted from the soil as per a sequential extraction procedure (SEP) and plant tissue was analysed for metalloid content. For As, there were no differences observed between the bioavailability of As in the As + Sb ₍cₒₘbᵢₙₑd₎ and As ₍ᵢₙdᵢᵥᵢdᵤₐₗ₎ treatments. For Sb, no increase in bioavailability was observed with co-contamination compared to single-Sb exposures for most concentrations except at 1250 mg/kg. Single-Sb was not toxic to I. aquatica shoot dry mass and length, but there was greater shoot Sb accumulation in the As + Sb ₍cₒₘbᵢₙₑd₎ than the Sb ₍ᵢₙdᵢᵥᵢdᵤₐₗ₎ treatment. In contrast, single-As was toxic to I. aquatica growth. When As and Sb were present together in the soil, there was a synergistic toxicity to shoot dry mass (EC₅₀ Toxic Unit (TU) was less than 1) and additive toxicity (EC₅₀ equal to 1 TU) to shoot length. This work shows that the co-occurrence of As and Sb in soil increases Sb bioavailability and can cause synergistic toxicity to an important agricultural crop.
اظهر المزيد [+] اقل [-]Efficient multiresidue determination method for 168 pharmaceuticals and metabolites: Optimization and application to raw wastewater, wastewater effluent, and surface water in Beijing, China النص الكامل
2020
Zhang, Yizhe | Duan, Lei | Wang, Bin | Liu, Cristina Su | Jia, Yanbo | Zhai, Nannan | Blaney, Lee | Yu, Gang
New analytical methods are needed to efficiently measure the growing list of priority pharmaceuticals in environmental samples. In this regard, a rapid, sensitive, and robust method was developed for quantitation of 168 pharmaceuticals and pharmaceutical metabolites using solid-phase extraction (SPE) and liquid chromatography with tandem mass spectrometry. The extraction protocol and instrumental efficiency were specifically addressed to increase analytical workload and throughput. The optimized protocols, which are five times more efficient than US EPA Method 1694, enabled analyte recoveries that ranged from 77% to 117% for 162 analytes with method quantitation limits (MQLs) as low as 0.1 ng L⁻¹. To verify the suitability of the improved analytical method for environmental samples, 24-h composite samples of raw wastewater and wastewater effluent, along with downstream surface water, were analyzed. Overall, 143/168 target compounds were identified in at least one of the samples, and 130/168 analytes were present at concentrations above their MQLs. The total mass concentration of the measured analytes decreased by 93% during wastewater treatment. The analyte concentrations in the wastewater effluent were comparable to those measured in surface water 1 km downstream of the wastewater discharge point. Ultimately, the comprehensive method will serve as an important tool to inform the occurrence, fate, transport, and toxicity of a large suite of priority pharmaceuticals and pharmaceutical metabolites in natural and engineered systems.
اظهر المزيد [+] اقل [-]Short term seasonal effects of airborne fungal spores on lung function in a panel study of schoolchildren residing in informal settlements of the Western Cape of South Africa النص الكامل
2020
Olaniyan, Toyib | Dalvie, Mohamed Aqiel | Röösli, Martin | Naidoo, Rajen N. | Künzli, Nino | de Hoogh, Kees | Berman, Dilys | Parker, Bhawoodien | Leaner, Joy | Jeebhay, Mohamed F.
The individual effects of biological constituents of particulate matter (PM) such as fungal spores, on lung function in children are not well known. This study investigated the seasonal short-term effect of daily variation in Alternaria and Cladosporium fungal spores on lung function in schoolchildren.This panel study evaluated 313 schoolchildren in informal settlements of the Western Cape of South Africa, exposed to spores of two commonly encountered fungi, Alternaria and Cladosporium species. The children provided forced-expiratory volume in 1-s (FEV₁) and peak-expiratory flow (PEF) measurements thrice daily for two consecutive school-weeks in summer and winter. Daily PM₁₀ levels, from a stationary ambient air quality monitor and fungal spore levels using spore traps were measured in each study area throughout the year. The effects of Alternaria and Cladosporium spores, on lung function were analysed for lag periods up to five-days, adjusting-for PM₁₀, other pollen exposures, study area, and other host and meteorological factors. Same-day exposure-response curves were computed for both fungal species.There was more variability in Alternaria spores level with noticeable peaks in summer. There were consistent lag-effects for Alternaria on PEF compared to Cladosporium, with the largest PEF deficit observed in winter (mean deficit: 13.78 L/min, 95%CI: 24.34 to −3.23 L/min) per 10spores/m³ increase in Alternaria spores on lag day-2. Although there were no observable lag-effects for Alternaria and Cladosporium on FEV₁, same-day effects of Cladosporium spores on FEV₁ was present across both seasons. Threshold effects of Alternaria on both PEF and FEV₁ deficits were apparent at levels of 100 spores/m³, but could not be explored for Cladosporium beyond the levels observed during the study.The study provides evidence for the independent effects of daily exposure to ambient fungal spores of Alternaria and Cladosporium on lung function deficits, more especially in winter for PEF.
اظهر المزيد [+] اقل [-]Water Quality Assessment Based on HFB I& BMWP Index In Karoon River ,Khouzestan Provience, (Northwest of Persian Gulf) النص الكامل
2020
Sahar Jalili
Score-based biotic indices are widely used to evaluate the water quality of streams and rivers. The main objective of this study was the assessmentof the water quality of Karoon River throught biotic indices based on the Family Biotic Index (HFBI), and the Biological Monitoring Working Party Score System (BMWP). Macroinveratabrate communities are one of the most used groups in assessment of water quality, since they respond directively to the level of contamination of aquatic ecosystems. Sampling were performed in 4 stations (Menikh, Zhian Canal, Bahrakani and Dahaneh). Sampling was carried in each station over one year ( winter, spring, summer and autumn). Macroinvertebrates were collected by the grab quantitative sampller. Four phylaum (Nematoda, Annelidae, Mollusca and Arthropoda) distributed amoung 11 families were sampled. Station1 (Menikh) had the highest Macroinveratabrate diversity and richness. The highest density of aquatic invertabrates were recorded in winter (Annelidae 46%, Crustacea 28% ,Mullusca 21% and Diptera 5% ) and spring ( Mullusca 58%, Crustacea 27%,Nematoda 10% and Anellidae 5%) respectively. The BMWP index showed that the water quality was in the reguallar category (for Menikh, Zhian Canal and Bahrakani) and in the poor category (for Dahaneh). HFBI index pointed out the water quality was in the reguallar catagorry (for Menikh, Zhian Canal and Bahrakani) and poor category (for Dahaneh) . Biotic indices used reflected the changes to the water quality.
اظهر المزيد [+] اقل [-]Identifying and prioritizing the factors influencing industrial waste management using Fuzzy Analytical Hierarchy Process (FAHP) النص الكامل
2020
Mina Moeeni | Ghasemali Omrani | Nematallah Khorasani | Reza Arjomandi
Over the past few decades, human societies have faced one of the most significant consequences of industrial development. That is the improper transportation and disposal of hazardous and industrial-specific waste, which accounts for a large share of the total pollution of the environment, and its destructive effects on creating environmental crises are quite evident. The plating industry is one of the main consumers of toxic chemicals used for different applications. However, because of the lack of a comprehensive model, hazardous waste management has not yet met the current needs, and its principles still require more development. This study was carried out using tools and standards including Multi-Criteria Decision Support Systems (MCDSS) and Fuzzy Analytical Hierarchy Process (FAHP) to rank the contributions of effective components to the plating industry in a case study conducted and implemented in Paitakht Industrial District of Tehran. In order to realize this objective, after extracting 10 components effective in optimizing the management of industrial wastes, questionnaires were used to survey experts to verify the components. The factors were identified using the Delphi method through the analysis of frequency carried out using a second questionnaire based on the results of the analysis of the data extracted from the first questionnaire. The results showed that components contributing to the optimal management of industrial waste included leadership and management, policy, strategy, technology and mode of collection and transportation, economic factors, policy making, expertise, culture, education, and the amount and composition of waste, in that order.
اظهر المزيد [+] اقل [-]Assessing the risk of environmental pollution caused by tourism activities (recreation – sports) in natural environments of Shahrood County النص الكامل
2020
Sepideh Hosseini Dinani | Seyed Mostafa Tayebi Sani | Bagher Morsal | Ali Fahiminejad
The purpose of this study is to identify environmental pollution caused by tourism activities in Shahrood county and environmental risk assessment. In the first step, tourism sites (recreational-sports) in the study area were identified. In the next step, the type and extent of environmental pollution in each were identified and their zoning map was drawn. Finally, risk assessment was performed using risk assessment models. The results showed that some types of environmental pollution can be seen in these areas, but the pollution caused by solid waste has been present in all tourist sites. The daily sewage pollution rate produced by natural tourism in Shahrood is relatively high and is about 140kg/day and the waste production rate is 10 tons per year. Also; the average measured sound level is 88dB. In terms of the level of risk of pollutants, the three most common types of pollution are solid waste and then sewage. The lowest type of pollution is related to air pollution. As for air pollution, the type of risk is obvious and the level of the aspect is low. In the case of noise pollution, the type of risk is obvious and the level of risk is high. In the case of wastewater pollution and waste pollution, the type of risk, the level and the level of the aspect is the ultimate. The principles of sustainable tourism in this region have not been observed and the need to develop a comprehensive and strategic model for tourism management is essential.
اظهر المزيد [+] اقل [-]Differential micropollutants bioaccumulation in European hake and their parasites Anisakis sp. النص الكامل
2020
Mille, Tiphaine | Soulier, Laurent | Caill-milly, Nathalie | Cresson, Pierre | Morandeau, Gilles | Monperrus, Mathilde
Organisms are exposed to various stressors including parasites and micropollutants. Their combined effects are hard to predict. This study assessed the trophic relationship, micropollutants bioaccumulation and infection degree in a host-parasite couple. Carbon and nitrogen isotopic ratios were determined in hake Merluccius merluccius muscle and in its parasite Anisakis sp.. Concentrations of both priority (mercury species and polychlorinated biphenyls congeners) and emerging (musks and sunscreens) micropollutants were also measured for the parasite and its host, to detect potential transfer of contaminants between the two species. The results showed partial trophic interaction between the parasite and its host, in accordance with the Anisakis sp. life encysted in hake viscera cavity. PCB transfer between the two species may result from some lipids uptake by the parasite, while no relation occurred for the two other contaminants. Finally, a positive correlation was found between the number of Anisakis sp. larvae and the methylmercury contamination for hake, emphasizing the assumption that the contamination level in methylmercury can weaken immune system of the host enough to affect parasite infection degree.
اظهر المزيد [+] اقل [-]Microplastics induce dose-specific transcriptomic disruptions in energy metabolism and immunity of the pearl oyster Pinctada margaritifera النص الكامل
2020
Gardon, Tony | Morvan, Lucie | Huvet, Arnaud | Quillien, Virgile | Soyez, Claude | Le Moullac, Gilles | Le Luyer, Jeremy
A combined approach integrating bioenergetics and major biological activities is essential to properly understand the impact of microplastics (MP) on marine organisms. Following experimental exposure of polystyrene microbeads (micro-PS of 6 and 10 μm) at 0.25, 2.5, and 25 μg L−1, which demonstrated a dose-dependent decrease of energy balance in the pearl oyster Pinctada margaritifera, a transcriptomic study was conducted on mantle tissue. Transcriptomic data helped us to decipher the molecular mechanisms involved in P. margaritifera responses to micro-PS and search more broadly for effects on energetically expensive maintenance functions. Genes related to the detoxification process were impacted by long-term micro-PS exposure through a decrease in antioxidant response functioning, most likely leading to oxidative stress and damage, especially at higher micro-PS doses. The immune response was also found to be dose-specific, with a stress-related activity stimulated by the lowest dose present after a 2-month exposure period. This stress response was not observed following exposure to higher doses, reflecting an energy-limited capacity of pearl oysters to cope with prolonged stress and a dramatic shift to adjust to pessimum conditions, mostly limited and hampered by a lowered energetic budget. This preliminary experiment lays the foundation for exploring pathways and gene expression in P. margaritifera, and marine mollusks in general, under MP exposure. We also propose a conceptual framework to properly assess realistic MP effects on organisms and population resilience in future investigations.
اظهر المزيد [+] اقل [-]Cultures of Dinophysis sacculus, D. acuminata and pectenotoxin 2 affect gametes and fertilization success of the Pacific oyster, Crassostrea gigas النص الكامل
2020
Gaillard, Sylvain | Le Goïc, Nelly | Malo, Florent | Boulais, Myrina | Fabioux, Caroline | Zaccagnini, Lucas | Carpentier, Liliane | Sibat, Manoella | Réveillon, Damien | Séchet, Veronique | Hess, Philipp | Hégaret, Helene
Cultures of Dinophysis sacculus, D. acuminata and pectenotoxin 2 affect gametes and fertilization success of the Pacific oyster, Crassostrea gigas النص الكامل
2020
Gaillard, Sylvain | Le Goïc, Nelly | Malo, Florent | Boulais, Myrina | Fabioux, Caroline | Zaccagnini, Lucas | Carpentier, Liliane | Sibat, Manoella | Réveillon, Damien | Séchet, Veronique | Hess, Philipp | Hégaret, Helene
Harmful algal blooms (HABs) of toxic species of the dinoflagellate genus Dinophysis are a threat to human health as they are mainly responsible for diarrheic shellfish poisoning (DSP) in the consumers of contaminated shellfish. Such contamination leads to shellfish farm closures causing major economic and social issues. The direct effects of numerous HAB species have been demonstrated on adult bivalves, whereas the effects on critical early life stages remain relatively unexplored. The present study aimed to determine the in vitro effects of either cultivated strains of D. sacculus and D. acuminata isolated from France or their associated toxins (i.e. okadaic acid (OA) and pectenotoxin 2 (PTX2)) on the quality of the gametes of the Pacific oyster Crassostrea gigas. This was performed by assessing the ROS production and viability of the gametes using flow cytometry, and fertilization success using microscopic counts. Oocytes were more affected than spermatozoa and their mortality and ROS production increased in the presence of D. sacculus and PTX2, respectively. A decrease in fertilization success was observed at concentrations as low as 0.5 cell mL−1 of Dinophysis spp. and 5 nM of PTX2, whereas no effect of OA could be observed. The effect on fertilization success was higher when both gamete types were concomitantly exposed compared to separate exposures, suggesting a synergistic effect. Our results also suggest that the effects could be due to cell-to-cell contact. These results highlight a potential effect of Dinophysis spp. and PTX2 on reproduction and recruitment of the Pacific oyster.
اظهر المزيد [+] اقل [-]Cultures of Dinophysis sacculus, D. acuminata and pectenotoxin 2 affect gametes and fertilization success of the Pacific oyster, Crassostrea gigas النص الكامل
2020
Gaillard, Sylvain | Le Goïc, Nelly | Malo, Florent | Boulais, Myrina | Fabioux, Caroline | Zaccagnini, Lucas | Carpentier, Liliane | Sibat, Manoella | Réveillon, Damien | Séchet, Véronique | Hess, Philipp | Hégaret, Hélène
Harmful algal blooms (HABs) of toxic species of the dinoflagellate genus Dinophysis are a threat to human health as they are mainly responsible for diarrheic shellfish poisoning (DSP) in the consumers of contaminated shellfish. Such contamination leads to shellfish farm closures causing major economic and social issues. The direct effects of numerous HAB species have been demonstrated on adult bivalves, whereas the effects on critical early life stages remain relatively unexplored. The present study aimed to determine the in vitro effects of either cultivated strains of D. sacculus and D. acuminata isolated from France or their associated toxins (i.e. okadaic acid (OA) and pectenotoxin 2 (PTX2)) on the quality of the gametes of the Pacific oyster Crassostrea gigas. This was performed by assessing the ROS production and viability of the gametes using flow cytometry, and fertilization success using microscopic counts. Oocytes were more affected than spermatozoa and their mortality and ROS production increased in the presence of D. sacculus and PTX2, respectively. A decrease in fertilization success was observed at concentrations as low as 0.5 cell mL⁻¹ of Dinophysis spp. and 5 nM of PTX2, whereas no effect of OA could be observed. The effect on fertilization success was higher when both gamete types were concomitantly exposed compared to separate exposures, suggesting a synergistic effect. Our results also suggest that the effects could be due to cell-to-cell contact. These results highlight a potential effect of Dinophysis spp. and PTX2 on reproduction and recruitment of the Pacific oyster.
اظهر المزيد [+] اقل [-]