خيارات البحث
النتائج 1451 - 1460 من 6,560
Antimony as a tracer of non-exhaust traffic emissions in air pollution in Granada (S Spain) using lichen bioindicators النص الكامل
2020
Parviainen, Annika | Papaslioti, Evgenia Maria | Casares Porcel, Manuel | Garrido, Carlos J.
We have studied the metal air pollution trends in a medium-sized Spanish city suffering from traffic emission using in-situ lichen Xanthoria parietina as a bioindicator. The large scale sampling included 97 samples from urban, metropolitan and remote control areas of Granada that were analyzed by Inductively Coupled Plasma-Mass Spectrometry. Enrichment factor of Sb exhibited severe anthropogenic enrichment, whereas Cu and Sb showed significantly higher median values in the urban areas with respect to metropolitan areas. Additionally, bioaccumulation ratios of V, Cr, Ni, Cu, Zn, Cd, Sb, and Pb —associated to exhaust and non-exhaust traffic emissions— enabled us to delineate hot spots of metal(loid) accumulation in the main accesses to the city, characterized by dense traffic and copious traffic jams. To distinguish non-exhaust emissions, we studied the spatial distribution of the Cu:Sb ratio —a tracer of brake wear— highlighting the surroundings of the highway and the main traffic accesses to the city likely due to sudden hard braking and acceleration during frequent traffic jams. Our study shows that the metal(loid) contents in lichens are excellent proxies for non-exhaust traffic emissions and that their contribution to the metal(loid) air pollution in Granada is more significant than previously thought.
اظهر المزيد [+] اقل [-]Usefulness of bee bread and capped brood for the assessment of monocyclic aromatic hydrocarbon levels in the environment النص الكامل
2020
Zięba, Katarzyna | Szostak, Elżbieta | Czekońska, Krystyna | Miśkowiec, Paweł | Moos-Matysik, Agnieszka | Nyczyk-Malinowska, Anna | Szentgyörgyi, Hajnalka
Monitoring airborne pollutants, like aromatic hydrocarbons, are raising more and more concerns recently. Various sampling techniques and methods are known to collect, measure, and analyse environmental pollution levels based on honey bee bodies or bee product samples. Although honey bees are studied in detail and sampling methods are becoming more and more sophisticated biological samples may significantly differ in pollutant accumulation, showing a wide range of pollution levels even in the same site and environment. We have compared the pollution levels of honey bee capped brood and bee bread (pollen collected by honey bees and deposited in the hive) originating from four sites during two years of study and twelve honey bee families near various pollution sources emitting monocyclic aromatic hydrocarbons (BTEX) to the environment. Our result showed, that the environmental monitoring of BTEX can be based on sampling honey bees, and bee bread in particular. However, we found a significant difference in the uptake of these pollutants regarding sample type. Pollen collected as a food source revealed consistently higher levels of BTEX than bee brood, as well as some other differences in pollution levels between samples and between seasons, as opposed to capped brood. Based on our results, we suggest that for measuring and monitoring of BTEX pollution in the environment the use of bee bread is a valuable source of information.
اظهر المزيد [+] اقل [-]Potential of siltstone and its composites with biochar and magnetite nanoparticles for the removal of cadmium from contaminated aqueous solutions: Batch and column scale studies النص الكامل
2020
Imran, Muhammad | Haq Khan, Zia Ul | Iqbal, Jibran | Shah, Noor Samad | Muzammil, Saima | Ali, Shafaqat | Muhammad, Nawshad | Aziz, Arwa | Murtaza, Behzad | Naeem, Muhammad Asif | Amjad, Muhammad | Shāhid, Muḥammad | Z̲ākir ʻAlī, | Rizwan, Muhammad
The present study is the first attempt to evaluate the pilot and batch scale adsorption potential of siltstone (SS) and its nanocomposites with biochar (EDB/SS), magnetite nanoparticles (MNPs/SS) and MNPs/EDB/SS for Cd removal from contaminated water. The SS, EDB/SS, MNPs/SS and MNPs/EDB/SS were characterized with FTIR, XRD, BET, SEM, TEM, TGA and point of zero charge (PZC). The effects of adsorbent dosage, contact time, initial Cd concentration, pH and presence of competing ions were evaluated on the Cd removal and its adsorption. The order for Cd removal was: MNPs/EDB/SS > MNPs/SS > EDB/SS > SS (95.86–99.72% > 93.10–98.5% > 89.66.98–98.40% > 74.90–90%). Column scale experiments yielded maximum retention (95%) of Cd even after 2 h of injection at 100 mg Cd/L. The exhausted SS, EDB/SS, MNPs/SS and MNPs/EDB/SS were reused without losing significant adsorption potential. Similarly, maximum Cd adsorption (117.38 mg/g) was obtained with MNPs/EDB/SS at dose 1.0 g/L. The results revealed that coexisting cations reduced the Cd removal due to competition with Cd ions. The experimental results were better explained with Freundlich isotherm model and pseudo 2nd order kinetic models. The results revealed that SS and its composites can be used efficiently for the removal of Cd from contaminated water.
اظهر المزيد [+] اقل [-]Glyphosate-based herbicides influence antioxidants, reproductive hormones and gut microbiome but not reproduction: A long-term experiment in an avian model النص الكامل
2020
Ruuskanen, Suvi | Rainio, Miia J. | Gómez-Gallego, Carlos | Selenius, Otto | Salminen, Seppo | Collado, Maria Carmen | Saikkonen, Kari | Saloniemi, Irma | Helander, Marjo
Controversial glyphosate-based herbicides (GBHs) are the most frequently used herbicides globally. GBH residues in the wild, in animal and human food may expose non-target organisms to health risks, yet the developmental and cumulative effects of GBHs on physiology and reproduction remain poorly understood. We present the first long-term study on the effects of subtoxic GBH exposure (160 mg/kg) on multiple key physiological biomarkers (cellular oxidative status and neurotransmitters), gut microbiome, reproductive hormones, and reproduction in an avian model. We experimentally exposed in Japanese quail females and males (Coturnix japonica) to GBHs and respective controls from the age of 10 days–52 weeks. GBH exposure decreased hepatic activity of an intracellular antioxidant enzyme (catalase), independent of sex, but did not influence other intracellular oxidative stress biomarkers or neurotransmitter enzyme (acetylcholinesterase). GBH exposure altered overall gut microbiome composition, especially at a younger age and in females, and suppressed potentially beneficial microbes at an early age. Many of the microbial groups increased in frequency from 12 to 28 weeks under GBH exposure. GBH exposure decreased male testosterone levels both at sexual maturity and at 52 weeks of exposure, but did not clearly influence reproduction in either sex (maturation, testis size or egg production). Future studies are needed to characterize the effects on reproductive physiology in more detail. Our results suggest that cumulative GBH exposure may influence health and reproduction-related traits, which is important in predicting their effects on wild populations and global poultry industry.
اظهر المزيد [+] اقل [-]Compliance of indoor air quality during sleep with legislation and guidelines – A case study of Lisbon dwellings النص الكامل
2020
Canha, Nuno | Alves, Ana Carolina | Marta, Catarina Simão | Lage, Joana | Belo, Joana | Faria, Tiago | Cabo Verde, Sandra | Viegas, Carla | Alves, Célia | Almeida, Susana Marta
This study aimed to provide a comprehensive characterisation of the indoor air quality during the sleeping period of 10 couples at Lisbon dwellings, using a multi-pollutant approach, and to understand how the compliance with legislation and guidelines was to assure a good indoor air quality. The assessment of indoor air quality was conducted in the cold season using real time monitors during the sleeping period for comfort parameters (temperature and relative humidity) and air pollutants (carbon dioxide – CO₂, carbon monoxide – CO, formaldehyde – CH₂O, total volatile organic compounds – VOCs, and particulate matter – PM₂.₅ and PM₁₀), together with active sampling of bioaerosols (fungi and bacteria) before and after the sleeping period. Lower compliance (less than 50% of the cases) with the Portuguese legislation was found for temperature, CO₂ (3440 ± 1610 mg m⁻³), VOCs (1.79 ± 0.99 mg m⁻³) and both bioaerosol types. In 70% of the cases, PM₂.₅ (15.3 ± 9.1 μg m⁻³) exceeded the WHO guideline of 10 μg m⁻³. All bedrooms presented air change rates above the recommended minimum value of 0.7 h⁻¹, highlighting that a good indoor air quality during sleep is not guaranteed.
اظهر المزيد [+] اقل [-]A radiological index for evaluating the impact of an abandoned uranium mining area in Salamanca, Western Spain النص الكامل
2020
The establishment of a screening index would be a powerful tool to decide whether abandoned uranium mining areas should be rehabilitated or decommissioned. Thus, in this work we established a radiological index which uses the activity concentrations of different groups of gamma emitters from the natural radioactive series of ²³⁸U, ²³⁵U, and ²³²Th, as well as ⁴⁰K and ¹³⁷Cs. These activity concentrations were calculated by using the absorbed gamma radiation dose value of 175 nGy h⁻¹ specified in the U.S. Code of Federal Regulations. We studied our index in an abandoned uranium mining area in Salamanca, Western Spain, and found that the most influential factors in this area were the presence of organic matter in the soil and the possible effect that plants and fungi may have on the retention of these aforementioned radionuclides. In addition, the results showed that contaminants are migrating in an easterly direction in line with the prevailing wind direction and we were able to identify areas in which the radiological risk is likely high. The mean effective dose rate was 2.51 ± 0.98 mSv y⁻¹ which was equivalent to the levels obtained in previous works.
اظهر المزيد [+] اقل [-]Benefit-risk associated with the consumption of fish bycatch from tropical tuna fisheries النص الكامل
2020
Sardenne, Fany | Lamboy, Nathalie Bodin | Médieu, Anaïs | Antha, Marisa | Arrisol, Rona | Le Grand, Fabienne | Bideau, Antoine | Munaron, Jean-Marie | Le Loc’h, François | Chassot, Emmanuel
Mercury, omega-3 (docosahexaenoic acid, DHA and eicosapentaenoic acid, EPA) and macronutrients (fat and proteins) were quantified on a wet weight (ww) basis in 20 species of fish taken as bycatch in tropical tuna fisheries. Based on a hazard quotient taking into account mercury and omega-3 contents, a benefit-risk assessment for the consumption of these pelagic species was conducted for three people categories: young children, children and adults. All fish bycatch were found to be an excellent source of proteins (min‒max = 14.4–25.2 g/100 g fillet), had low omega-6/omega-3 ratios (<1, except for silky shark), and had mercury content below the safety limits defined by sanitary agencies. Silky shark and Istiophoridae had the highest mercury contents (min‒max = 0.029–0.317 ppm ww). Omega-3 contents were the lowest in silky shark (0.2 ± 0.2 mg/100 g fillet) and the highest in striped marlin (3.6 ± 3.2 g/100 g fillet). Billfishes (Istiophoridae, including striped marlin), minor tunas (Scombridae), and Carangidae had the highest omega-3 contents (min‒max = 0.68–7.28 g/100 g fillet). The highest hazard quotient values obtained for silky shark and great barracuda reflected a lower nutritional benefit (i.e., low omega-3 source) than risk (i.e., mercury exposure), making them not advisable for consumption. Eight species had low hazard quotients, and among them cottonmouth jack and flat needlefish were found of high health interest (high protein, moderate fat contents, and low omega-6/omega-3 ratio). A daily serving portion of 85–200 g (according to people category) can be recommended for these species. Batfish, and to a lower extent pompano dolphinfish and brassy chub, can also be consumed safely and would provide greater health benefits than risks. These results advocate for a better access of these species to local populations.
اظهر المزيد [+] اقل [-]Effects of cadmium, inorganic mercury and methyl-mercury on the physiology and metabolomic profiles of shoots of the macrophyte Elodea nuttallii النص الكامل
2020
Cosio, Claudia | Renault, David
Macrophytes are known to bioaccumulate metals, but a thorough understanding of tolerance strategies and molecular impact of metals in aquatic plants is still lacking. The present study aimed to compare Hg and Cd effects in a representative macrophyte, Elodea nuttallii using physiological endpoints and metabolite profiles in shoots and cytosol.Exposure 24 h to methyl-Hg (30 ng L⁻¹), inorganic Hg (70 ng L⁻¹) and Cd (280 μg L⁻¹) did not affect photosynthesis, or antioxidant enzymes despite the significant accumulation of metals, confirming a sublethal stress level. In shoots, Cd resulted in a higher level of regulation of metabolites than MeHg, while MeHg resulted in the largest number of regulated metabolites and IHg treatment regulated no metabolites significantly. In cytosol, Cd regulated more metabolites than IHg and only arginine, histidine and mannose were reduced by MeHg exposure. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of data suggested that exposure to MeHg resulted in biochemical changes including aminoacyl-tRNA biosynthesis, glycine, serine and threonine metabolism, nitrogen metabolism, arginine and proline metabolism, cyanoamino acid metabolism, while the treatment of Cd stress caused significant variations in aminoacyl-tRNA biosynthesis and branched-chain amino acids pathways. Data supports an impact of MeHg on N homeostasis, while Cd resulted in an osmotic stress-like pattern and IHg had a low impact. Marked differences in the responses to MeHg and IHg exposure were evidenced, supporting different molecular toxicity pathways and main impact of MeHg on non-soluble compartment, while main impact of IHg was on soluble compartment. Metabolomics was used for the first time in this species and proved to be very useful to confirm and complement recent knowledge gained by transcriptomics and proteomics, highlighting the high interest of multi-omics approaches to identify early impact of environmental pollution.
اظهر المزيد [+] اقل [-]Active emigration from climate change-caused seawater intrusion into freshwater habitats النص الكامل
2020
Venâncio, C. | Ribeiro, R. | Lopes, I.
Ecological risk assessment associated with seawater intrusions has been supported on the determination of lethal/sublethal effects following standard protocols that force exposure neglecting the ability of mobile organisms to spatially avoid salinized environments. Thus, this work aimed at assessing active emigration from climate change-caused seawater intrusion into freshwater habitats. To specific objectives were delineated: first, to compute median 12-h avoidance conductivities (AC₅₀,₁₂ₕ) for freshwater species, and second, to compare it with literature data (LC₅₀,₄₈ ₒᵣ ₉₆ₕ, EC₅₀,₆ ₒᵣ ₂₁d) to assess the relevance of the inclusion of stressor-driven emigration into risk assessment frameworks. Four standard test species, representing a broad range of ecological niches – Daphnia magna, Heterocypris incongruens, Danio rerio and Xenopus laevis – were selected. The salt NaCl was used as a surrogate of natural seawater to create the saline gradient, which was established in a 7-compartment system.At each specific LC₅₀, ₄₈ ₒᵣ ₉₆ₕ, the proportion of avoiders were well above 50%, ranging from 71 to 94%. At each LC₅₀, considering also avoiders, populations would decline by 85–97%. Furthermore, for D. magna and X. laevis it was noticed that at the lowest conductivities eliciting mortality, the avoidance already exceeded 50%.The results showed that the emigration from salinity-disturbed habitats exists and that can even be more sensitive than standard endpoints. Looking solely to standard endpoints involving forced exposure may greatly underestimate the risk of local population extinction, because habitat function can be severely disrupted, with subsequent stressor-driven emigration, before any adverse physiological effects at the organism level. Thus, the present study highlights the need to include non-forced exposure testing into ecological risk assessment, namely of salinity-menaced costal freshwaters.
اظهر المزيد [+] اقل [-]Contamination may induce behavioural plasticity in the habitat selection by shrimps: A cost-benefits balance involving contamination, shelter and predation النص الكامل
2020
Araújo, Cristiano V.M. | Pereira, Karyna C. | Sparaventi, Erica | González-Ortegón, Enrique | Blasco, Julián
When shrimps select a habitat, the presence of elements like predators, shelter and contamination might determine if an area is preferred or avoided. We hypothesised that when shrimps are exposed to a situation in which they have to select whether to avoid contamination, seek shelter or protect themselves against predators, they will avoid the situation that supposes a higher cost for their survival (cost-benefits balance). The current study aimed to assess the plasticity of the selection behaviour of the freshwater shrimp Atyaephyra desmarestii between moving to a clean and unprotected area (no shelter and with a risk of predation), thus avoiding exposure to contamination, or moving to a contaminated and protected area (with shelters), thereby avoiding potential predators. Shrimps were experimentally exposed in a free-choice system simulating a heterogeneous environment with a contaminant (copper), shelter and a predator signal (kairomones of Salmo trutta). The shrimps avoided the copper by moving towards a less contaminated area, both in the absence or presence of shelter. When confronted with a choice between a cleaner zone with no shelter and a contaminated zone with shelter, the shrimps preferred being in the cleanest area. However, when the uncontaminated area contained a predator signal, the shrimps balanced the risk of predation and exposure to contamination by selecting a moderately contaminated area relatively further away from the predator signals. In summary, contamination might favour a plasticity of the habitat selection behaviour of shrimps, modifying the cost-benefits balance of such a selection.
اظهر المزيد [+] اقل [-]