Уточнить поиск
Результаты 461-470 из 4,044
Infectious bacterial pathogens, parasites and pathological correlations of sewage pollution as an important threat to farmed fishes in Egypt Полный текст
2016
Mahmoud, Mahmoud A. | Abdelsalam, Mohamed | Mahdy, Olfat A. | El Miniawy, Hala M.F. | Ahmed, Zakia A.M. | Osman, Ahmed H. | Mohamed, Hussein M.H. | Khattab, A.M. | Zaki Ewiss, M.A.
This paper is a part of a multi-disciplinary research “Application of Decentralized On-Site Water Treatment System in Egypt for Use in Agriculture and Producing Safe Fish and Animal Proteins”.The project aimed to investigate the environmental impact of implementing sewage water before and after treatment using the effluent of the on-site decentralized Japanese' Johkasou system, in agriculture and producing fish protein. The aim is to establish such system in Egypt to strengthen the sanitary conditions of water resources. In the present study, the impact of the sewage pollution in some fish farms at El-Fayyum, Port Said and El-Dakahlia governorates in Egypt was carried out. Water and fish (Oreochromis niloticus and Mugil cephalus) samples were collected from private fish farms of such localities. Bacteriological and chemical examination of water samples revealed the existence of coliforms and many other bacterial species of significant human health hazards. The chemical parameters of water showed a marked deviation from normal levels while examination of fish flesh specimens indicated contamination with Streptococcus Sp., Staphylococcus Sp., and Salmonella in all examined localities. Other bacterial isolates of human health importance (Morganella morganii, Pseudomonas cepacia and Enterococcos durans) were identified. The parasitological examination revealed the presence of encysted metacercariae (EMC); Diplostomatidae, Prohemistomatidae and Heterphyidae. Moreover, two protozoan parasites (Mxyoboulus tilapiae and Ichthyophthirius multifilis) were also recorded. The histopathological examination revealed mild tissue reaction in case of bacterial infection and severe pathological lesions in different organs in case of EMC infection. Lamellar hyperplasia and mononuclear cell infiltration in branchial tissue was common findings. In skeletal muscles, atrophy of muscle fibres, myolysis and myophagia were detected.
Показать больше [+] Меньше [-]Multiscale correlations of iron phases and heavy metals in technogenic magnetic particles from contaminated soils Полный текст
2016
Yu, Xiuling | Lu, Shenggao
Technogenic magnetic particles (TMPs) are carriers of heavy metals and organic contaminants, which derived from anthropogenic activities. However, little information on the relationship between heavy metals and TMP carrier phases at the micrometer scale is available. This study determined the distribution and association of heavy metals and magnetic phases in TMPs in three contaminated soils at the micrometer scale using micro-X-ray fluorescence (μ-XRF) and micro-X-ray absorption near-edge structure (μ-XANES) spectroscopy. Multiscale correlations of heavy metals in TMPs were elucidated using wavelet transform analysis. μ-XRF mapping showed that Fe was enriched and closely correlated with Co, Cr, and Pb in TMPs from steel industrial areas. Fluorescence mapping and wavelet analysis showed that ferroalloy was a major magnetic signature and heavy metal carrier in TMPs, because most heavy metals were highly associated with ferroalloy at all size scales. Multiscale analysis revealed that heavy metals in the TMPs were from multiple sources. Iron K-edge μ-XANES spectra revealed that metallic iron, ferroalloy, and magnetite were the main iron magnetic phases in the TMPs. The relative percentage of these magnetic phases depended on their emission sources. Heatmap analysis revealed that Co, Pb, Cu, Cr, and Ni were mainly derived from ferroalloy particles, while As was derived from both ferroalloy and metallic iron phases. Our results indicated the scale-dependent correlations of magnetic phases and heavy metals in TMPs. The combination of synchrotron based X-ray microprobe techniques and multiscale analysis provides a powerful tool for identifying the magnetic phases from different sources and quantifying the association of iron phases and heavy metals at micrometer scale.
Показать больше [+] Меньше [-]Hepatic oxidative stress and metal subcellular partitioning are affected by selenium exposure in wild yellow perch (Perca flavescens) Полный текст
2016
Ponton, Dominic E. | Caron, Antoine | Hare, Landis | Campbell, Peter G.C.
Yellow perch (Perca flavescens) collected from 11 lakes in the Canadian mining regions of Sudbury (Ontario) and Rouyn-Noranda (Quebec) display wide ranges in the concentrations of cadmium (Cd), nickel (Ni), selenium (Se), and thallium (Tl) in their livers. To determine if these trace elements, as well as copper (Cu) and zinc (Zn), are causing oxidative stress in these fish, we measured three biochemical indicators (glutathione (GSH), glutathione disulfide (GSSG) and thiobarbituric acid-reactive substances (TBARS)) in their livers. We observed that 44% of the yellow perch that we collected were at risk of cellular oxidative stress and lipid peroxidation. Considering all fish from all lakes, higher liver Se concentrations were coincident with both lower proportions of GSSG compared to GSH and lower concentrations of TBARS, suggesting that the essential trace-element Se acts as an antioxidant. Furthermore, fish suffering oxidative stress had higher proportions of Cd, Cu and Zn in potentially sensitive subcellular fractions (organelles and heat-denatured proteins) than did fish not suffering from stress. This result suggests that reactive oxygen species may oxidize metal-binding proteins and thereby reduce the capacity of fish to safely bind trace metals. High Cd concentrations in metal-sensitive subcellular fractions likely further exacerbate the negative effects of lower Se exposure.
Показать больше [+] Меньше [-]Uptake, metabolism and sub-lethal effects of BDE-47 in two estuarine invertebrates with different trophic positions Полный текст
2016
Díaz-Jaramillo, M. | Miglioranza, K.S.B. | Gonzalez, M. | Barón, E. | Monserrat, J.M. | Eljarrat, E. | Barceló, D.
Two microcosm types -sediment-biota and biota-biota- were constructed to simulate different pathways of BDE-47 uptake, metabolism and oxidative stress effects in two key estuarine invertebrates (polychaete Laeonereis acuta and crab Cyrtograpsus angulatus). In the sediment-biota experiment, both species were exposed to spiked sediments; an environmentally reported and a high concentration of BDE-47 for 2 weeks. In the biota-biota experiment, crabs were fed with polychaetes pre-exposed to BDE-47 in the sediment-biota experiment. The sediment-biota experiment first revealed that polychaetes significantly accumulated BDE-47 (biota-sediment accumulation factor >2; p < 0.05) to a much greater extent than the crab organs (muscle, hepatopancreas, gills) at both sediment concentrations. For oxidative stress responses, polychaete and crab tissues exposed to spiked sediment showed a significant increase (p < 0.05) of only glutathione S-transferase (GST) activity with respect to controls in both BDE-47 concentrations. No lipid peroxidation (TBARS) or total antioxidant capacity (ACAP) changes were evident in the species or organs exposed to either BDE-47 sediment concentration. The biota-biota experiment showed that feeding crabs with pre-exposed polychaetes caused BDE-47 accumulation in organs as well as significant amounts of BDE-47 eliminated through feces (p < 0.05). Unlike the sediment-biota exposure, crabs fed with pre-exposed BDE-47 polychaetes showed the most conspicuous oxidative stress responses. Significant changes in GST and ACAP in both hepatopancreas and gills, in addition to enhanced TBARS levels in the hepatopancreas with respect to controls (p < 0.05), revealed that BDE-47 assimilated by invertebrates represents a potential source of toxicity to their predators. No methoxylated metabolites (MeO-PBDEs) were detected during BDE-47 metabolism in the invertebrates in either of the two different exposure types. In contrast, hydroxylated metabolites (OH-PBDEs) were detected in polychaetes and crab organs/feces in both experiments. Our results demonstrate that PBDE hydroxylation is one of the main biotransformation routes of BDE-47 in estuarine animals, which could be associated with the oxidative stress responses found.
Показать больше [+] Меньше [-]Size evolution of ultrafine particles: Differential signatures of normal and episodic events Полный текст
2016
Joshi, Manish | Khan, Arshad | Anand, S. | Sapra, B.K.
The effect of fireworks on the aerosol number characteristics of atmosphere was studied for an urban mega city. Measurements were made at 50 m height to assess the local changes around the festival days. Apart from the increase in total number concentration and characteristic accumulation mode, short-term increase of ultrafine particle concentration was noted. Total number concentration varies an order of magnitude during the measurement period in which peak occurs at a frequency of approximately one per day. On integral scale, it seems not possible to distinguish an episodic (e.g. firework bursting induced aerosol emission) and a normal (ambient atmospheric changes) event. However these events could be differentiated on the basis of size evolution analysis around number concentration peaks. The results are discussed relative to past studies and inferences are drawn towards aerosol signatures of firework bursting. The short-term burst in ultrafine particle concentration can pose an inhalation hazard.
Показать больше [+] Меньше [-]Quality screening for air quality monitoring data in China Полный текст
2016
Liu, Jianzheng | Li, Weifeng | Li, Jie
Particulate matter data obtained from the national air quality monitoring network in China has become an essential and critical data source for many current and forthcoming studies as well as the formulation and implementation of air pollution regulatory policies on particulate matter (PM2.5 and PM10). However, the quality control of this data is dubitable and can affect many future studies and policies. This study identifies and elucidates two significant quality control issues with the data. They are PM2.5 levels exceeding concurrent co-located PM10 levels and the registration of same concentrations for consecutive hours at some stations. Future studies utilizing particulate matter data need to acknowledge and address these issues to ensure accurate and reliable results.
Показать больше [+] Меньше [-]Covalent triazine-based framework: A promising adsorbent for removal of perfluoroalkyl acids from aqueous solution Полный текст
2016
Wang, Bingyu | Lee, Linda S. | Wei, Chenhui | Fu, Heyun | Zheng, Shourong | Xu, Zhaoyi | Zhu, Dongqiang
Perfluoroalkyl acids (PFAAs) are highly stable, persistent, and ubiquitous in the environment with significant concerns growing with regards to both human and ecosystem health. Due to the high stability to both biological and chemical attack, the only currently feasible approach for their removal from water is adsorbent technology. The main objective of this study was to assess a covalent triazine-based framework (CTF) adsorbent for removal from aqueous solutions of perfluoro C4, C6, and C8 carboxylates and sulfonates including the two C8s most commonly monitored, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Adsorption affinity and capacity were quantified and compared to three commonly used sorbents: pulverized microporous activated carbon, single-walled carbon nanotubes, and Amberlite IRA-400 anion-exchange resin. CTF adsorbent exhibited pronouncedly higher adsorption affinity and capacity of PFAAs than other test sorbents. The remarkably strong adsorption to CTF can be attributed to the favored electrostatic interaction between the protonated triazine groups on the inner wall of the hydrophobic CTF pore and the negatively charged head groups of the PFAAs intercalated between the CTF layers. The homogeneous, nanosized pores (1.2 nm) of CTF hindered adsorption of a large-sized dissolved humic acid, thus minimizing the suppression of PFAA adsorption. Additionally, regeneration of CTF was easily accomplished by simply raising pH > 11, which inhibited the electrostatic adsorptive interaction of PFAAs.
Показать больше [+] Меньше [-]Does arsenic play an important role in the soil microbial community around a typical arsenic mining area? Полный текст
2016
Wu, Fan | Wang, Jun-Tao | Yang, Jun | Li, Jing | Zheng, Yuan-Ming
Arsenic (As) can cause serious hazards to human health, especially in mining areas. Soil bacterial communities, which are critical parts of the soil ecosystem, were analyzed directly for soil environmental factors. As a consequence, it is of great significance to understand the ecological risk of arsenic contamination on bacteria, especially at the local scale. In this study, 33 pairs of soil and grain samples were collected from the corn and paddy fields around an arsenic mining area in Shimen County in Hunan Province, China. Significant differences were found between the soil nitrogen, As concentrations, and bacteria activities among these two types of land use. According to the structural equation model (SEM) analysis, compared with other environmental factors, soil As was not the key factor affecting the bacterial community, even when grain As was beyond the threshold of the national food hygiene standards of China. In the corn field, soil pH was the main factor dominating the bacterial richness, composition and grain As. Meanwhile, in the paddy field the soil total nitrogen (TN) and total carbon (TC) were the main factors impacting the bacterial richness, and the bacterial community composition was mainly affected by pH. The interactions between grain As and soil As were weak in the corn field. The bacterial communities played important roles in the food chain risk of As. The local policy of transforming paddy soil to dry land could greatly reduce the health risk of As through the food chain.
Показать больше [+] Меньше [-]Anthropogenic impact on mangrove sediments triggers differential responses in the heavy metals and antibiotic resistomes of microbial communities Полный текст
2016
Cabral, Lucélia | Júnior, Gileno Vieira Lacerda | Pereira de Sousa, Sanderson Tarciso | Dias, Armando Cavalcante Franco | Lira Cadete, Luana | Andreote, Fernando Dini | Hess, Matthias | de Oliveira, Valéria Maia
Mangroves are complex and dynamic ecosystems highly dependent on diverse microbial activities. In the last decades, these ecosystems have been exposed to and affected by diverse human activities, such as waste disposal and accidental oil spills. Complex microbial communities inhabiting the soil and sediment of mangroves comprise microorganisms that have developed mechanisms to adapt to organic and inorganic contaminants. The resistance of these microbes to contaminants is an attractive property and also the reason why soil and sediment living microorganisms and their enzymes have been considered promising for environmental detoxification. The aim of the present study was to identify active microbial genes in heavy metals, i.e., Cu, Zn, Cd, Pb and Hg, and antibiotic resistomes of polluted and pristine mangrove sediments through the comparative analysis of metatranscriptome data. The concentration of the heavy metals Zn, Cr, Pb, Cu, Ni, Cd, and Hg and abundance of genes and transcripts involved in resistance to toxic compounds (the cobalt-zinc-cadmium resistance protein complex; the cobalt-zinc-cadmium resistance protein CzcA and the cation efflux system protein CusA) have been closely associated with sites impacted with petroleum, sludge and other urban waste. The taxonomic profiling of metatranscriptome sequences suggests that members of Gammaproteobacteria and Deltaproteobacteria classes contribute to the detoxification of the polluted soil. Desulfobacterium autotrophicum was the most abundant microorganism in the oil-impacted site and displayed specific functions related to heavy metal resistance, potentially playing a key role in the successful persistence of the microbial community of this site.
Показать больше [+] Меньше [-]Impact of bisphenol A (BPA) on early embryo development in the marine mussel Mytilus galloprovincialis: Effects on gene transcription Полный текст
2016
Balbi, Teresa | Franzellitti, Silvia | Fabbri, Rita | Montagna, Michele | Fabbri, Elena | Canesi, Laura
Bisphenol A (BPA), a monomer used in plastic manufacturing, is weakly estrogenic and a potential endocrine disruptor in mammals. Although it degrades quickly, it is pseudo-persistent in the environment because of continual inputs, with reported concentrations in aquatic environments between 0.0005 and 12 μg/L. BPA represents a potential concern for aquatic ecosystems, as shown by its reproductive and developmental effects in aquatic vertebrates.In invertebrates, endocrine-related effects of BPA were observed in different species and experimental conditions, with often conflicting results, indicating that the sensitivity to this compound can vary considerably among related taxa. In the marine mussel Mytilus galloprovincialis BPA was recently shown to affect early development at environmental concentrations. In this work, the possible effects of BPA on mussel embryos were investigated at the molecular level by evaluating transcription of 13 genes, selected on the basis of their biological functions in adult mussels. Gene expression was first evaluated in trocophorae and D-veligers (24 and 48 h post fertilization) grown in physiological conditions, in comparison with unfertilized eggs. Basal expressions showed a general up-regulation during development, with distinct transcript levels in trocophorae and D-veligers. Exposure of fertilized eggs to BPA (10 μg/L) induced a general upregulation at 24 h pf, followed by down regulation at 48 h pf. Mytilus Estrogen Receptors, serotonin receptor and genes involved in biomineralization (Carbonic Anydrase and Extrapallial Protein) were the most affected by BPA exposure. At 48 h pf, changes in gene expression were associated with irregularities in shell formation, as shown by scanning electron microscopy (SEM), indicating that the formation of the first shelled embryo, a key step in mussel development, represents a sensitive target for BPA. Similar results were obtained with the natural estrogen 17β-estradiol. The results demonstrate that BPA and E2 can affect Mytilus early development through dysregulation of gene transcription.
Показать больше [+] Меньше [-]