خيارات البحث
النتائج 1601 - 1610 من 6,473
Improvement in hourly PM2.5 estimations for the Beijing-Tianjin-Hebei region by introducing an aerosol modeling product from MASINGAR
2020
Zhang, Yixiao | Wang, Wei | Ma, Yingying | Wu, Lixin | Xu, Weiwei | Li, Jia
This study improves traditional PM₂.₅ estimation models by combining an hourly aerosol optical depth from the Advanced Himawari Imager onboard Himawari-8 with a newly introduced predictor to estimate hourly PM₂.₅ concentrations in the Beijing–Tianjin–Hebei (BTH) region from November 1, 2018 to October 31, 2019. The new predictor is an hourly PM₂.₅ forecasting product from the Model of Aerosol Species IN the Global AtmospheRe (MASINGAR). Comparative experiments were conducted by utilizing three extensively used regression models, namely, multiple linear regression (MLR), geographically weighted regression (GWR), and linear mixed effects (LME). A ten-fold cross validation (CV) demonstrated that the MASINGAR product significantly improved the performances of these models. The introduced product increased the model’s determination coefficients (from 0.316 to 0.379 for MLR, from 0.393 to 0.445 for GWR, and from 0.718 to 0.765 for LME), decreased their root mean square errors (from 38.2 μg/m³ to 36.4 μg/m³ for MLR, from 36.0 μg/m³ to 34.4 μg/m³ for GWR, and from 24.5 μg/m³ to 22.4 μg/m³ for LME) and mean absolute errors (from 25.2 μg/m³ to 23.3 μg/m³ for MLR, from 23.5 μg/m³ to 21.8 μg/m³ for GWR, and from 15.2 μg/m³ to 13.7 μg/m³ for LME). Then, a well-trained LME model was utilized to estimate the spatial distributions of hourly PM₂.₅ concentrations. Highly polluted localities were clustered in the central and southern areas of the BTH region, and the least polluted area was in northwestern Hebei. Seasonal PM₂.₅ levels averaged from the hourly estimations exhibited the highest concentrations (55.4 ± 56.8 μg/m³) in the winter and lowest concentrations (25.1 ± 18.2 μg/m³) in the summer.Introducing the PM₂.₅ products from MASINGAR can significantly improve the performance of traditional models for surface PM₂.₅ estimations by 7–20%.
اظهر المزيد [+] اقل [-]Sex-dependent locomotion and physiological responses shape the insecticidal susceptibility of parasitoid wasps
2020
Andreazza, Felipe | Haddi, Khalid | Nörnberg, Sandro D. | Guedes, Raul Narciso C. | Nava, Dori E. | Oliveira, Eugênio E.
The adaptive fitness of insect species can be shaped by how males and females respond, both physiologically and behaviorally, to environmental challenges, such as pesticide exposure. In parasitoid wasps, most toxicological investigations focus only on female responses (e.g., survival and especially parasitism abilities), leaving the male contributions to adaptive fitness (survival, locomotion, mate search) poorly investigated. Here, we evaluated the toxicity of the spinosyn insecticide spinosad against the South American fruit fly, Anastrepha fraterculus, and we used the parasitoid wasp Diachasmimorpha longicaudata (Ashmead) to evaluate whether sex-linked locomotory and physiological responses would influence the susceptibility of these organisms to spinosad. Our results revealed that D. longicaudata males were significantly more susceptible (median lethal time (LT₅₀) = 24 h) to spinosad than D. longicaudata females (LT₅₀ = 120 h), which may reflect the differences in their locomotory and physiological (e.g., respiratory) responses to mitigate insecticide exposure. Compared to D. longicaudata females, male wasps were lighter (P < 0.001), walked for longer distances (P < 0.001) and periods (P < 0.001), and exhibited higher sensilla densities in their tarsi (P = 0.008), which may facilitate their intoxication with the insecticide. These findings indicate that male parasitoids should not be exempt from insecticide selectivity tests, as these organisms can be significantly more affected by such environmental challenges than their female conspecifics.
اظهر المزيد [+] اقل [-]Long-lasting effect of mercury contamination on the soil microbiota and its co-selection of antibiotic resistance
2020
Mahbub, Khandaker Rayhan | King, William L. | Siboni, Nachshon | Nguyen, Viet Khue | Rahman, Mohammad Mahmudur | Megharaj, Mallavarapu | Seymour, Justin R. | Franks, Ashley E. | Labbate, Maurizio
Antibiotic resistance genes (ARGs) in the environment are an exposure risk to humans and animals and is emerging as a global public health concern. In this study, mercury (Hg) driven co-selection of ARGs was investigated under controlled conditions in two Australian non-agricultural soils with differing pH. Soils were spiked with increasing concentrations of inorganic Hg and left to age for 5 years. Both soils contained ARGs conferring resistance to tetracycline (tetA, tetB), sulphonamides (sul1), trimethoprim (dfrA1) and the ARG indicator class 1 integron-integrase gene, intI1, as measured by qPCR. The last resort antibiotic vancomycin resistance gene, vanB and quinolone resistance gene, qnrS were not detected. Hg driven co-selection of several ARGs namely intI1, tetA and tetB were observed in the alkaline soil within the tested Hg concentrations. No co-selection of the experimental ARGs was observed in the neutral pH soil. 16S rRNA sequencing revealed proliferation of Proteobacteria and Bacteriodetes in Hg contaminated neutral and alkaline soils respectively. Multivariate analyses revealed a strong effect of Hg, soil pH and organic carbon content on the co-selection of ARGs in the experimental soils. Additionally, although aging caused a significant reduction in Hg content, agriculturally important bacterial phyla such as Nitrospirae did not regrow in the contaminated soils. The results suggest that mercury can drive co-selection of ARGs in contaminated non-agricultural soils over five years of aging which is linked to soil microbiota shift and metal chemistry in the soil.
اظهر المزيد [+] اقل [-]Sargassum horneri extract containing mojabanchromanol attenuates the particulate matter exacerbated allergic asthma through reduction of Th2 and Th17 response in mice
2020
Herath, Kalahe Hewage Iresha Nadeeka Madushani | Kim, Hyo-jin | Mihindukulasooriya, Suyama Prasansali | Kim, Areum | Kim, Hyun Jung | Jeon, You-Jin | Jee, Youngheun
Airborne particulate matter (PM) has become a serious health issue causing pulmonary diseases such as asthma. Due to the side effects and non-specificity of conventional drugs, there is a need to develop natural-product-based alternative treatments. Sargassum horneri is a brown alga shown to have anti-oxidant, anti-inflammatory, and anti-allergic effects. Thus, we sought to determine whether ethanol extract of Sargassum horneri (SHE) mitigates the effect of PM exposure on asthma development. To establish a mouse model of asthma, BALB/c mice were sensitized with ovalbumin (OVA, 10 μg) and challenged with PM (5 mg/m³) for 7 days consecutively. SHE (200, 400 mg/kg), Prednisone (5 mg/kg), or PBS was daily administrated orally before PM exposure. SHE mitigated PM exacerbated dendritic cell activation. More importantly, SHE restrained Th2 polarization by attenuating transcription factors GATA3 and STAT5, which further mitigated the expression of Th2 cytokines interleukin (IL)-4, IL-5, and IL-13 in the lung homogenates of PM-exacerbated asthmatic mice. SHE further attenuated PM-exacerbated eosinophil infiltration in the lung, trachea, and BALF. In addition, SHE markedly mitigated the activation of mast cells and the IgE level in serum. Concomitantly, SHE further restrained the Th17 cell response in PM-exposed allergic mice through attenuating expression of transcription factors RORγT, STAT3 and expression of relevant effector cytokines IL-17a. This resulted in mitigated neutrophil infiltration in the lung. Taken together, SHE significantly suppressed PM-exacerbated hypersecretion of mucus in asthmatic mice. These results suggest that SHE has therapeutic potential for treating PM-exacerbated allergic asthma through concomitantly inhibiting Th2/Th17 responses.
اظهر المزيد [+] اقل [-]Exposure to acetamiprid influences the development and survival ability of worker bees (Apis mellifera L.) from larvae to adults
2020
Shi, Jingliang | Zhang, Ruonan | Pei, Yalin | Liao, Chunhua | Wu, Xiaobo
In most cases, honey bees experience pesticide pollution in a long-term period through direct or indirect exposure, such as the development process from larvae to the pre-harvest stage. At present, little is known about how honey bees respond to pesticide stresses during the continuous development period. This study aims to examine effects of long-term acetamiprid exposure on the development and survival of honey bees, and further present the expression profile in larvae, 1-day-old, and 7-day-old adult worker bees that related to immune, detoxification, acetylcholinesterase (AChE) and memory. Honey bees from 2-day-old larvae to 14-day-old adults except the pupal stage were continuously fed with different acetamiprid solutions (0, 5, and 25 mg/L). We found that acetamiprid over 5 mg/L disturbed the development involving birth weight and emergence rate of newly emerged bees, and reduced the proportion of capped cells of larvae at 25 mg/L; gene expression related to immune and detoxification of worker bees exposed to acetamiprid was roughly activated, returned and then inhibited from larval to emerged and to the late adult stage, respectively. Moreover, lifespans of bees treated with acetamiprid at 25 mg/L were significantly reduced. The present study reflects the potential risk for honey bees continuously exposed to acetamiprid in the development stage.
اظهر المزيد [+] اقل [-]Ecotoxicity of three plant-based biodiesels and diesel using, Eisenia fetida
2020
Bamgbose, Ifeoluwa A. | Anderson, Todd A.
Soil pollution is growing at an alarming rate in today’s industrialized world as a result of increasing anthropogenic activities, either intentional (e.g., use of fertilizers and pesticides, irrigation with untreated wastewater, or land application of sewage sludge) or accidental (e.g., oil spills or leaching from landfills). Terrestrial soil pollution from transportation fuels such as Diesel or Biodiesel is inevitable as they are part of life’s necessities. Biodiesel is considered an environmental friendly fuel due to its non-hydrocarbon composition and low particulate matter emission. However, there are still some controversies regarding biodiesel environmental toxicity to terrestrial life. Little is known about the ecotoxicity of plant-based biodiesels to soil organisms. In the present study, three ecotoxicological tests including an earthworm (Eisenia fetida) 14-day soil toxicity test, a filter paper contact toxicity test, and a cocoon hatchability test were performed to examine the toxic effects of three plant-based biodiesels - safflower methyl ester (SaME), castor methyl ester (CME), and castor ethyl ester (CEE), with Diesel fuel. Unlike Diesel, the biodiesels were less toxic based on low earthworm mortality in the soil toxicity test. However significant morbidity responses (e.g., weight loss, coiling, posterior and anterior fragmentation, and excessive discharge of coelomic fluid) were observed in earthworms exposed to biodiesel. Further, in the cocoon hatchability test, biodiesels were equally toxic to Diesel at 2% and 5% soil concentrations, with no hatching success.
اظهر المزيد [+] اقل [-]Anthropogenic noise is associated with telomere length and carotenoid-based coloration in free-living nestling songbirds
2020
Grunst, Melissa L. | Grunst, Andrea S. | Pinxten, Rianne | Eens, Marcel
Growing evidence suggests that anthropogenic noise has deleterious effects on the behavior and physiology of free-living animals. These effects may be particularly pronounced early in life, when developmental trajectories are sensitive to stressors, yet studies investigating developmental effects of noise exposure in free-living populations remain scarce. To elucidate the effects of noise exposure during development, we examined whether noise exposure is associated with shorter telomeres, duller carotenoid-based coloration and reduced body mass in nestlings of a common urban bird, the great tit (Parus major). We also assessed how the noise environment is related to reproductive success. We obtained long-term measurements of the noise environment, over a ∼24-h period, and characterized both the amplitude (measured by LAₑq, LA₉₀, LA₁₀, LAₘₐₓ) and variance in noise levels, since more stochastic, as well as louder, noise regimes might be more likely to induce stress. In our urban population, noise levels varied substantially, with louder, but less variable, noise characteristic of areas adjacent to a highway. Noise levels were also highly repeatable, suggesting that individuals experience consistent differences in noise exposure. The amplitude of noise near nest boxes was associated with shorter telomeres among smaller, but not larger, brood members. In addition, carotenoid chroma and hue were positively associated with variance in average and maximum noise levels, and average reflectance was negatively associated with variance in background noise. Independent of noise, hue was positively related to telomere length. Nestling mass and reproductive success were unaffected by noise exposure. Results indicate that multiple dimensions of the noise environment, or factors associated with the noise environment, could affect the phenotype of developing organisms, that noise exposure, or correlated variables, might have the strongest effects on sensitive groups of individuals, and that carotenoid hue could serve as a signal of early-life telomere length.
اظهر المزيد [+] اقل [-]Food sources are more important than biomagnification on mercury bioaccumulation in marine fishes
2020
Yoshino, Kenji | Mori, Keisuke | Kanaya, Gen | Kojima, Shigeaki | Henmi, Yasuhisa | Matsuyama, Akito | Yamamoto, Megumi
Marine animals often accumulate various harmful substances through the foods they ingest. The bioaccumulation levels of these harmful substances are affected by the degrees of pollution in the food and of biomagnification; however, which of these sources is more important is not well-investigated for mercury (Hg) bioaccumulation. Here we addressed this issue in fishes that inhabit the waters around Minamata Bay, located off the west coast of Kyushu Island in Kumamoto Prefecture, Japan. The total Hg concentration (hereafter [THg]) and carbon and nitrogen stable isotope ratios (δ¹³C and δ¹⁵N) were analyzed in the muscle tissue of 10 fish species, of which more than five individuals were caught by gillnet. Except one species, each was separated into two trophic groups with respective lower and higher δ¹³C values ranging from −17‰ to −16‰ and −15‰ to −14‰, which suggested that the fishes depended more on either phytoplankton- and microphytobenthos-derived foods (i.e., pelagic and benthic trophic pathways), respectively. Linear mixed effects models showed that the Hg levels were significantly associated with both δ¹⁵N and the differences in the trophic groups. [THg] increased with δ¹⁵N (i.e., indicative of higher trophic levels), but the slopes did not differ between the two trophic groups. [THg] was significantly higher in the group with higher δ¹³C values than in those with lower δ¹³C values. The effect size from marginal R squared (R²) values showed that the variation in [THg] was strongly ascribed to the trophic group difference rather than δ¹⁵N. These results suggest that the substantial Hg bioaccumulation in the fishes of Minamata Bay is mainly an effect of ingesting the microphytobenthos-derived foods that contain Hg, and that the subsequent biomagnification is secondary.
اظهر المزيد [+] اقل [-]Effect of pyrolysis conditions on bone char characterization and its ability for arsenic and fluoride removal
2020
Alkurdi, Susan S.A. | Al-Juboori, Raed A. | Bundschuh, Jochen | Bowtell, Les | McKnight, Stafford
This study examined arsenite [As(III)], arsenate [As(V)] and fluoride (F⁻) removal potential of bone char produced from sheep (Ovis aries) bone waste. Pyrolysis conditions tested were in the 500 °C–900 °C range, for a holding time of 1 or 2 h, with or without N₂ gas purging. Previous bone char studies mainly focused on either low or high temperature range with limited information provided on As(III) removal. This study aims to address these gaps and provide insights into the effect of pyrolysis conditions on bone char sorption capacity. A range of advanced chemical analyses were employed to track the change in bone char properties. As pyrolysis temperature and holding time increased, the resulting pH, surface charge, surface roughness, crystallinity, pore size and CEC all increased, accompanied by a decrease in the acidic functional groups and surface area. Pyrolysis temperature was a key parameter, showing improvement in the removal of both As(III) and As(V) as pyrolysis temperature was increased, while As(V) removal was higher than As(III) removal overall. F⁻ removal displayed an inverse relationship with increasing pyrolysis temperature. Bone char prepared at 500 °C released significantly more dissolved organic carbon (DOC) then those prepared at a higher temperature. The bone protein is believed to be a major factor. The predominant removal mechanisms for As were surface complexation, precipitation and interaction with nitrogenous functional groups. Whereas F⁻ removal was mainly influenced by interaction with oxygen functional groups and electrostatic interaction. This study recommends that the bone char pyrolysis temperature used for As and F⁻ removal are 900 °C and 650 °C, respectively.
اظهر المزيد [+] اقل [-]Effect of biochar modified with magnetite nanoparticles and HNO3 for efficient removal of Cr(VI) from contaminated water: A batch and column scale study
2020
Imran, Muhammad | Khan, Zia Ul Haq | Iqbal, Muhammad Mohsin | Iqbal, Jibran | Shah, Noor Samad | Munawar, Saba | Ali, Shafaqat | Murtaza, Behzad | Naeem, Muhammad Asif | Rizwan, Muhammad
Chromium (Cr) poses serious consequences on human and animal health due to its potential carcinogenicity. The present study aims at preparing a novel biochar derived from Chenopodium quinoa crop residues (QBC), its activation with magnetite nanoparticles (QBC/MNPs) and strong acid HNO₃ (QBC/Acid) to evaluate their batch and column scale potential to remove Cr (VI) from polluted water. The QBC, QBC/MNPs and QBC/Acid were characterized with SEM, FTIR, EDX, XRD as well as point of zero charge (PZC) to get an insight into their adsorption mechanism. The impact of different process parameters including dose of the adsorbent (1–4 g/L), contact time (0–180 min), initial concentration of Cr (25–200 mg/L) as well as solution pH (2–8) was evaluated on the Cr (VI) removal from contaminated water. The results revealed that QBC/MNPs proved more effective (73.35–93.62-%) for the Cr (VI) removal with 77.35 mg/g adsorption capacity as compared with QBC/Acid (55.85–79.8%) and QBC (48.85–75.28-%) when Cr concentration was changed from 200 to 25 mg/L. The isothermal experimental results follow the Freundlich adsorption model rather than Langmuir, Temkin and Dubinin-Radushkevich adsorption isotherm models. While kinetic adsorption results were well demonstrated by pseudo second order kinetic model. Column scale experiments conducted at steady state exhibited excellent retention of Cr (VI) by QBC, QBC/MNPs and QBC/Acid at 50 and 100 mg Cr/L. The results showed that this novel biochar (QBC) and its modified forms (QBC/Acid and QBC/MNPs) are applicable with excellent reusability and stability under acidic conditions for the practical treatment of Cr (VI) contaminated water.
اظهر المزيد [+] اقل [-]