خيارات البحث
النتائج 3141 - 3150 من 4,937
Impact of emissions controls on ambient carbonyls during the Asia-Pacific Economic Cooperation summit in Beijing, China النص الكامل
2019
Zhou, Xueming | Tan, Jihua | Qin, Juanjuan | Hu, Jingnan | Duan, Jingchun | Chen, Rongzhi
Beijing and its surrounding areas implemented a series of stringent measures to ensure good air quality during the Asia-Pacific Economic Cooperation (APEC) summit. These measures included restrictions on traffic, constructions, and industrial activities. The diurnal variations of carbonyls, 24-h PM₂.₅, and its chemical species were investigated before, during, after APEC, and the 2015 summer. The average concentrations of carbonyls, formaldehyde, acetaldehyde, and acetone were decreased by 65.2%, 78.6%, 41.5%, and 55.6% during APEC, respectively. The concentrations of propene equivalent, the ozone formation potential, and the contribution to OH· removal by carbonyls during APEC were approximately 27–33% of those during the preceding interval. The temporal variation of carbonyls during APEC was similar to that of other air pollutants, except for O₃; however, the diurnal variation of carbonyls was consistent with that of O₃, with the highest values at noon and the lowest ones at night during APEC. Large variations in C1/C2 (0.95–9.41) and C2/C3 (5.70–15.71) were observed during the sampling period. The correlations analysis, diagnostical ratios, and diurnal variations of carbonyls indicated that primary sources were not an important source and secondary formation was the dominant source of atmospheric carbonyls during the entire period. The control measures not only reduced primary carbonyl emissions but also dramatically reduced secondary carbonyl precursors, such as NOₓ and volatile organic compounds (VOCs), resulting in the low level of carbonyls during APEC. In addition, the potential health effects of carbonyls were evaluated and the cancer risk from formaldehyde and acetaldehyde was significantly higher before APEC than during the other intervals.
اظهر المزيد [+] اقل [-]Effects of cadmium exposure on antioxidant enzymes and histological changes in the mud shrimp Austinogebia edulis (Crustacea: Decapoda) النص الكامل
2019
Das, Shagnika | Tseng, Li-Chun | Zhou, Ji | Wang, Lan | Souissi, Sami | Hwang, Jiang-Shiou
The trace metal cadmium (Cd) is a toxic pollutant known to induce oxidative stress and other sublethal to lethal effects on aquatic organisms. We exposed the marine mud shrimp Austinogebia edulis to Cd concentrations of 0, 0.5, and 5 mg/kg for up to 4 days (24, 48, 72, 96 h). We studied the activity of antioxidant enzymes in the hepatopancreas, gill, and muscle of A. edulis. Antioxidant enzymes (SOD, CAT, and GPx) decreased with increasing Cd concentration and extended exposure time in these three organs of the mud shrimp A. edulis. Increasing Cd concentration led to an increase in ROS and resulted ultimately in membrane lipid peroxidation at higher Cd concentrations. Significant damage of the hepatopancreas of A. edulis was noticed at higher concentrations of Cd, showing damages like the disappearance of epithelial cell boundaries, detachment of cells from the basal lamina, cellular swelling, necrosis, and reduction of glycogen. In conclusion, Cd caused oxidative damage by reducing the activities of antioxidant enzymes and by damaging the tissue structure in major organs of the mud shrimp A. edulis.
اظهر المزيد [+] اقل [-]Increased DMT-1 expression in placentas of women living in high-Cd-contaminated areas of Thailand النص الكامل
2019
Somsuan, Keerakarn | Phuapittayalert, Laorrat | Srithongchai, Yupa | Sonthi, Pattaraporn | Supanpaiboon, Wisa | Hipkaeo, Wiphawi | Sakulsak, Natthiya
Cadmium (Cd) is a toxic heavy metal and contamination was reported in soil and rice in several areas of Thailand. Humans are normally exposed to environmental Cd, leading to gradual Cd accumulation in their bodies, including the placenta. DMT-1 is a divalent metal transporter which is found in placental tissue and plays a vital role in the transportation of Fe²⁺ and Cd²⁺. This study investigated DMT-1 protein and mRNA expressions in full term human placentas comparing those from high-Cd-contaminated areas (high-Cd group) and low-Cd-contaminated areas (low-Cd group), n = 6 per group. The maternal blood Cd (B-Cd) and placental Cd (P-Cd) of the high-Cd group was significantly raised in comparison with those in the low-Cd group. DMT-1 in the fetal portion of the placentas was localized in the apical and basal portions of the cytoplasm of the syncytiotrophoblastic cells, the endothelium of fetal capillaries which is functional structure of the placental barrier, and was also found in the cytoplasm of Hofbauer cells. Moreover, DMT-1 localization in the maternal portion was also detected in most decidual cells. In addition, the DMT-1 protein and mRNA expressions in the high-Cd group were significantly higher than those in the low-Cd group. Therefore, we suggest that pregnant women, who are exposed to environmental Cd, show an increased level of Cd in their maternal blood and this Cd can accumulate in the placenta. Intracellular Cd may induce DMT-1 mRNA transcription which further translates into DMT-1 protein, which can then function as a reciprocal Cd transporter in placental tissue.
اظهر المزيد [+] اقل [-]The effects of energy on investment, human health, environment and economic growth: empirical evidence from China النص الكامل
2019
Azam, Muhammad | Khan, Abdul Qayyum | Ozturk, Ilhan
The role of energy cannot be passed over in the process of economic growth and development in any economy. China consumes colossal quantity of energy; thus, the central objectives of this study is to empirically evaluate the linkages among energy use, environment by CO₂ emissions, human health by health expenditures, Foreign Direct Investment (FDI) inflows, and real GDP per capita used for economic growth over the period of 1995–2016 for China. The nature of the data directed to employ the Canonical cointegrating regression (CCR) method for unknown parameter estimation. Four equations have estimated namely for FDI, health, environment, and economic growth. The result for China during the period under the study reveals that energy consumption has significant positive impact on FDI, health, environment, and economic growth. The study results suggest that policy makers need to chalk out effective policy for effective utilization of energy so as to encourage permissible economic growth and development in China.
اظهر المزيد [+] اقل [-]Hydroponics: are we moving towards that direction only because of the environment? A discussion on forecasting and a systems review النص الكامل
2019
Manos, Dimitrios-Panagiotis | Xydis, George
During the evolution of the human, agriculture and land utilization was inevitably connected with survival in nature. Human activity was not only restricted to the production of agricultural products but also extended into many other sectors, such as the production of several industrial-made products, mining, and usage of fossil fuels as a standard method of generating electricity. However, the intense urbanization phenomenon ultimately caused, during the last few decades, the degradation of our natural environment. As a result, the quality (and quantity) of produced food we consume has significantly decreased. The need for the evolution of alternative methods of cultivation is constant and always a hot topic, especially in order to confront the multiple problems that conventional agriculture has. Hydroponics, an innovative cultivation method, comes to solve many of these problems.
اظهر المزيد [+] اقل [-]Dissolved organic matter in urban forestland soil and its interactions with typical heavy metals: a case of Daxing District, Beijing النص الكامل
2019
Zhao, Chen | Gao, Shi-Jie | Zhou, Lei | Li, Xiang | Chen, Xi | Wang, Chong-Chen
As an active substance, dissolved organic matter (DOM) acts a pivotal part in heavy metals (HMs) transportation from urban forestland soil to aquatic ecosystem. In this study, the soil samples from 35 individual subareas were scientifically collected with the aid of geographical information system (GIS) technology. UV-visible (UV-vis) and excitation-emission matrix (EEM)–related parameters suggested that the DOM in urban forestland soil mainly originated from terrestrial and microbial sources. Fluorescence quenching titration associated with parallel factor (PARAFAC) modeling was applied to quantify the complexation ability of four HMs (Cu, Cd, Pb, and Ni) and DOM in urban forestland soil. One fulvic-like (C1), two humic-like (C2 and C3), and one protein-like fluorophores (C4) were identified by EEM-PARAFAC modeling. Considerable differences in fluorescence quenching curves were observed between individual organic constituents and target HMs. Among the four HMs, addition of Cu(II) ions resulted in EEM spectra quenching of each PARAFAC-decomposed organic constituent. However, relatively strong fluorescence quenching phenomena were only detected in humic-like constituents (C2 and C3) with the titration of Pb(II) and Ni(II), which revealed that these types of organic constituent were predominantly responsible for Pb(II) and Ni(II) binding in urban forestland soil–derived DOM. Furthermore, considering the resistant nature of C2 and C3 constituents along with their significant quenching effects for the four target HMs, the concentrations of humic-like constituents in urban forestland soil may be a useful parameter to evaluate the potential risk of HMs immobilization and transformation.
اظهر المزيد [+] اقل [-]Pyrethroid pesticide metabolite, 3-PBA, in soils: method development and application to real agricultural soils النص الكامل
2019
Bragança, Idalina | Lemos, Paulo C. | Delerue-Matos, Cristina | Domingues, Valentina F.
3-Phenoxybenzoic acid (3-PBA) is a shared metabolite of several synthetic pyrethroid pesticides (SPs) resulting from environmental degradation of parent compounds and thus occurs frequently as a residue in samples. Hence, the importance of 3-PBA evaluation after pyrethroid application. There is a gap of analytical methods to determine 3-PBA in soil samples. Therefore, an analytical method that combines the solid-phase extraction (SPE) and gas chromatography–mass spectrometry (GC/MS) detection has been developed for the determination of 3-PBA in soil samples. The analytical method was validated in terms of linearity, sensitivity, intra- and inter-day batch precisions, recoveries, and quantification limits. An SPE method using a Strata X cartridge allows obtaining limits of detection and quantification equal to 4.0 and 13.3 ng g⁻¹, respectively. Under optimized conditions, the method average recovery levels ranged from 70.3 to 93.5% with a relative standard deviation below 3.4%. Method intra- and inter-day precision was under 5.0 and 4.8%, respectively. The developed method was applied to 11 agricultural soil samples in the north of Portugal. The developed methodology allowed for the determination of the pyrethroid metabolite, 3-PBA, in agricultural soil samples at levels of few ng g⁻¹. Graphical abstract ᅟ
اظهر المزيد [+] اقل [-]Virulence-associated traits and in vitro biofilm-forming ability of Escherichia coli isolated from a major river traversing Northern India النص الكامل
2019
Singhal, Neelja | Singh, Nambram Somendro | Maurya, Anay Kumar | Virdi, Jugsharan Singh
Several strains of Escherichia coli harbor virulence traits, resulting in E. coli–related intestinal and extra-intestinal infections. Various studies have reported that extra-intestinal pathogenic E. coli (ExPEC) strains were prevalent in nonhuman reservoirs, including environmental waterways. It is therefore important to identify the pathogenic potential and/or ExPEC status of E. coli strains inhabiting the aquatic environments associated with anthropogenic activities. Besides virulence-associated genes, biofilm production also helps in the survival of E. coli in environmental waterbodies. Thus, the aim of the current study was to assess the virulence potential, ExPEC status, and biofilm-producing capability of E. coli isolated from the River Yamuna, a major river traversing the National Capital Region of Delhi, India. We also tried to discern a co-relation, if any, between virulence, biofilm formation, and antimicrobial resistance in these strains. Our results indicated that virulence-associated genes were scarce and none of the strain qualified the molecular criteria essential for ExPEC. This suggested that E. coli strains which can presumably cause human extra-intestinal infections were not prominent in the River Yamuna. However, the fact that more than 80% of the aquatic E. coli isolates were moderate and strong biofilm producers suggests that E. coli in these environments might serve as opportunistic pathogens. Also, no unequivocal association was observed between biofilm production, virulence, and β-lactamase genes in E. coli strains. As per the best of our knowledge, this is the first study where the relationship between virulence, biofilms, and antimicrobials has been examined in E. coli, isolated from an Indian urban aquatic waterbody.
اظهر المزيد [+] اقل [-]Amelioration of toxicopathological effects of cadmium with silymarin and milk thistle in male Japanese quail (Coturnix japonica) النص الكامل
2019
Saleemi, Muhammad Kashif | Tahir, Muhammad Waseem | Abbas, Rao Zahid | Akhtar, Masood | Ali, Aamir | Javed, Muhammad Tariq | Fatima, Zahida | Zubair, Muhammad | Bhatti, Sheraz Ahmed | Zahoor Ul Hassan,
Cadmium is an important widely distributed heavy metal in the environment due to its several industrial uses, while milk thistle is an important herb and is a source of several antioxidant particularly silymarin which is a pharmacological active substance present in seeds of milk thistle plant (Silybum marianum). The current study investigated pathological effects of cadmium (Cd) and their amelioration with silymarin (SL) and milk thistle (MT) quails. A total of 144 quails were equally divided into 9 groups and given different combinations of cadmium chloride (150 and 300 mg/kg feed), SL (250 mg/kg), and MT (10 g/kg) feed. Parameters studied were clinical signs, mortality, organ weights, testes weight and volume, and gross and microscopic pathology. Results of this study indicated an increased mortality and reduced body weight in cadmium-treated quails. Quails were dull, depressed compared with control. Swollen hemorrhagic liver along with atrophied testes were also observed in these groups. No active spermatozoa were observed in lumen of seminiferous tubules of Cd-treated birds presenting arrest of spermatogenesis. Supplementing MT and SL ameliorated mortality, organ weights, spermatogenesis, and histopathological lesions. It may be concluded that MT and SL proved beneficial in cadmium-induced toxicities in Japanese quails.
اظهر المزيد [+] اقل [-]Heavy metal distribution and uptake by maize in a mudflat soil amended by vermicompost derived from sewage sludge النص الكامل
2019
Zuo, Wengang | Xu, Kaida | Zhang, Wenjie | Wang, Yao | Gu, Chuanhui | Bai, Yanchao | Shan, Yuhua | Dai, Qigen
Sewage sludge has been regarded as an economic and efficient soil amendment for mudflat soil amendment despite of the concern of heavy metal contamination. Converting sewage sludge into vermicompost by earthworms may be effective to minimize the risk of heavy metal contamination caused by direct application of sewage sludge in mudflat soil. The objective of this study was to assess the feasibility of vermicompost amendment (VA), and its influence on heavy metal contamination compared with sewage sludge amendment (SSA) in mudflat soil. The results showed that VA improved the physicochemical properties of mudflat soil by decreasing soil bulk density, salinity, and pH, increasing soil organic carbon, nitrogen, and phosphorus contents in the soil. Consequently, the maize biomass and yield were significantly elevated by VA. For heavy metals, VA increased total Cd, Cu, Ni, Pb, and Zn concentrations in mudflat soil, and the maximum increments occurred at 250 t ha⁻¹. Available Cd, Cu, Mn, Ni, and Zn concentrations significantly increased with increasing VA rates. VA increased the accumulation of Cd, Cu, Mn, Ni, Pb, and Zn in maize tissues, especially in root of maize. Compared with SSA under the condition of maintaining equal carbon input, VA allowed heavy metals to accumulate in a more stable binding form in the top 20-cm layer of mudflat soil. Thus, the risk of runoff and leaching of heavy metals and their bioavailability to plants reduced in mudflat soil. As a result, VA decreased the accumulation of heavy metals in maize plant compared with SSA in mudflat soil. In summary, vermicompost can be an effective and safe substitute for sewage sludge for mudflat amendment.
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