خيارات البحث
النتائج 1831 - 1840 من 3,240
Comparison of Cr(VI) removal by activated sludge and dissolved organic matter (DOM): importance of UV light النص الكامل
2015
Gong, Yu-Feng | Song, Jia | Ren, Hai-Tao | Han, Xu
Removal of toxic Cr(VI) by activated sludge and DOM derived from activated sludge was investigated in this study. A rapid increase in TOC concentration from 50.93 to 127.40 mg L⁻¹ is observed during the Cr(VI) removal process by activated sludge in the pH range of 2–9. Removal efficiencies of Cr(VI) by either activated sludge or DOM greatly decreased with the increasing initial pH. Kinetics of Cr(VI) removal by activated sludge indicate that both biosorption and bioreduction are involved in the Cr(VI) removal. Cr(VI) removal by DOM is slow in dark, but it is greatly enhanced when UV light is applied. The first-order constant increases from 0.0033 (in dark) to 0.079 min⁻¹ (UV illumination) at pH 2.0 and 1068 mg L⁻¹ DOM. The enhancement of Cr(VI) reduction is due to the generation of the reactive intermediates such as O₂ ●_ and DOM* as DOM absorbed light energy, which plays important roles in the reduction of Cr(VI).
اظهر المزيد [+] اقل [-]Emergy-based comparative analysis of energy intensity in different industrial systems النص الكامل
2015
Liu, Zhe | Geng, Yong | Wang, Hui | Sun, Lu | Ma, Zhixiao | Tian, Xu | Yu, Xiaoman
With the rapid economic development, energy consumption of China has been the second place in the world next to the USA. Usually, measuring energy consumption intensity or efficiency applies heat unit which is joule per gross domestic production (GDP) or coal equivalent per GDP. However, this measuring approach is only oriented by the conversion coefficient of heat combustion which does not match the real value of the materials during their formation in the ecological system. This study applied emergy analysis to evaluate the energy consumption intensity to fill this gap. Emergy analysis is considered as a bridge between ecological system and economic system, which can evaluate the contribution of ecological products and services as well as the load placed on environmental systems. In this study, emergy indicator for performing energy consumption intensity of primary energy was proposed. Industrial production is assumed as the main contributor of energy consumption compared to primary and tertiary industries. Therefore, this study validated this method by investigating the two industrial case studies which were Dalian Economic Development Area (DEDA) and Fuzhou economic and technological area (FETA), to comparatively study on their energy consumption intensity between the different kinds of industrial systems and investigate the reasons behind the differences. The results show that primary energy consumption (PEC) of DEDA was much higher than that of FETA during 2006 to 2010 and its primary energy consumption ratio (PECR) to total emergy involvement had a dramatically decline from year 2006 to 2010. In the same time, nonrenewable energy of PEC in DEDA was also much higher than that in FETA. The reason was that industrial structure of DEDA was mainly formed by heavy industries like petro-chemistry industry, manufacturing industries, and high energy-intensive industries. However, FETA was formed by electronic business, food industry, and light industries. Although the GDP of DEDA was much higher than that of FETA, its energy intensity was higher as well. Through the 5-year development, energy consumption intensity in DEDA made a significant reduction from 3.90E+16 seJ/$ to 1.84E+16 seJ/$, which was attributed by the improvement of industrial structure, construction of eco-industrial park and circular economic industrial park. The proposed emergy indicator for demonstrating energy consumption intensity overcame the weakness that the indicator was only transformed from the heat burning. Therefore, this study shows an optional way to measure energy consumption intensity from the perspective of material ecological contribution.
اظهر المزيد [+] اقل [-]Photodegradation of neonicotinoid insecticides in water by semiconductor oxides النص الكامل
2015
Fenoll, José | Garrido, Isabel | Hellín, Pilar | Flores, Pilar | Navarro, Simón
The photocatalytic degradation of three neonicotinoid insecticides (NIs), thiamethoxam (TH), imidacloprid (IM) and acetamiprid (AC), in pure water has been studied using zinc oxide (ZnO) and titanium dioxide (TiO₂) as photocatalysts under natural sunlight and artificial light irradiation. Photocatalytic experiments showed that the addition of these chalcogenide oxides in tandem with the electron acceptor (Na₂S₂O₈) strongly enhances the degradation rate of these compounds in comparison with those carried out with ZnO and TiO₂ alone and photolytic tests. Comparison of catalysts showed that ZnO is the most efficient for the removal of such insecticides in optimal conditions and at constant volumetric rate of photon absorption. Thus, the complete disappearance of all the studied compounds was achieved after 10 and 30 min of artificial light irradiation, in the ZnO/Na₂S₂O₈ and TiO₂/Na₂S₂O₈ systems, respectively. The highest degradation rate was noticed for IM, while the lowest rate constant was obtained for AC under artificial light irradiation. In addition, solar irradiation was more efficient compared to artificial light for the removal of these insecticides from water. The main photocatalytic intermediates detected during the degradation of NIs were identified.
اظهر المزيد [+] اقل [-]Dioxins in the semen of men with infertility النص الكامل
2015
Galimova, E. F. | Amirova, Z. K. | Galimov, Sh. N.
The purpose of the present study was to assess ejaculate contamination by polychlorinated dibenzo-p-dioxins/furans in male infertility. The database of 168 infertile and 49 fertile men was included in the study. Dioxin content was determined using gas chromatography/high-resolution mass spectrometry (GC/HRMS). In the ejaculate of infertile men, the content of dioxins and furans was 2.2–2.3 times higher than in fertile donors. The maximum level of the most toxic dioxin congener was detected in pathospermia. Contamination of semen of infertile men by polychlorinated dibenzo-p-dioxins/furans supports the hypothesis about the relationship between environmental factors and reproductive health.
اظهر المزيد [+] اقل [-]Profenofos insecticide degradation by novel microbial consortium and isolates enriched from contaminated chili farm soil النص الكامل
2015
Siripattanakul-Ratpukdi, Sumana | Vangnai, Alisa S. | Sangthean, Puttaporn | Singkibut, Sirinuttakan
Profenofos (PF) is one of the heavily used organophosphorus pesticides (OPPs) of which its contamination is ubiquitous in an agricultural area. This study aims to acquire and characterize PF-degrading bacterial cultures from contaminated soil. OPP degradation by the novel isolates was then investigated. The experiment was performed at the initial PF concentration of 20 mg/L. The result showed that the enriched consortium comprised three predominant PF-degrading strains designated as PF1, PF2, and PF3. The isolates (PF1, PF2, and PF3) were characterized as Pseudomonas plecoglossicida, Pseudomonas aeruginosa, and P. aeruginosa, respectively. A consortium and all isolates could utilize PF as a sole carbon source with PF removal of more than 90 % via a hydrolysis process. The bacterial growth and PF degradation rates followed the first-order kinetic reaction with the rates of 0.4 to 2.7/h and 0.15 to 1.96/h, respectively. Additional carbon supplement deteriorated PF biodegradation. The enriched cultures were also capable for degrading chlorpyrifos and dicrotophos pesticides (33–73 % removal). The results indicated that the consortium and isolates are efficient for PF and other OPP degradation and have potential for PF remediation.
اظهر المزيد [+] اقل [-]DDT and its metabolites are linked to increased risk of type 2 diabetes among Saudi adults: a cross-sectional study النص الكامل
2015
Al-Othman, AbdulAziz A. | Abd-Alrahman, Sherif H. | Al-Daghri, Nasser M.
Organochlorine (OC) pesticides have recently been associated with type 2 diabetes in several non-Asian general populations. As there is currently an epidemic of type 2 diabetes mellitus in Asia. The prevalence and incidence of diabetes is increasing rapidly worldwide including many Arab Gulf countries. According to a community-based national epidemiological health survey, the overall prevalence of diabetes mellitus in Saudi adults (age group of 30–50 years) is 23.7 %. A recent study by Al-Daghri et al. (BMC Med 9:76, 2011) reported that the prevalence of diabetes mellitus in the Kingdom of Saudi Arabia (KSA) is 31.6 %. We investigated the associations between OC pesticides and type 2 diabetes in Saudi Arabia using a simple, sensitive, rapid, and selective gas chromatography coupled with mass spectrometry (GC-MS) method that has been recently developed. A total of 280 Saudi adults (136 diabetes mellitus (DM) patients and 144 non-DM controls) were randomly selected from the Riyadh Cohort Study for inclusion. The diagnosis of diabetes was based on established diagnosis and medications taken. Blood dichlorodiphenyltrichloroethane (DDT) and its derivatives were quantified using GC-MS. Residues of DDT and its derivatives were analyzed in serum by means of gas chromatography with a mass spectrometry detector. Associations between DDT exposure and T2DM were analyzed by logistic regression. DDT and its derivatives and serum concentrations of DDT and its derivative DDE showed the strongest and most significant association to type 2 diabetes in both cross-sectional and prospective studies. Associations of DDT and its derivatives varied across different diabetes-related components of the metabolic syndrome. It positively and significantly associated with four of the five of these components especially elevated triacylglycerol, high fasting glucose, high blood pressure, and HOMA-IR but negatively and significantly with HDL. Possible biological mechanisms are discussed. This study confirms previous reports relating organochlorine pesticide (OCP) exposure to diabetes and suggests possible hormonal pathways deserving further exploration. The study will be one of the first to shed light on the associations of serum levels of total DDTs and DDT derivatives among the Saudi Arab ethnicity, and diabetes type 2 chronic noncommunicable diseases are highly prevalent.
اظهر المزيد [+] اقل [-]Chemical characterization and spatial distribution of PAHs and heavy hydrocarbons in rural sites of Campania Region, South Italy النص الكامل
2015
Monaco, D. | Riccio, A. | Chianese, E. | Adamo, P. | Di Rosa, S. | Fagnano, M.
In this paper, the behaviour and distribution patterns of heavy hydrocarbons and several polycyclic aromatic hydrocarbon (PAH) priority pollutants, as listed by the US Environmental Protection Agency, were evaluated in 891 soil samples. The samples were collected in three expected polluted rural sites in Campania (southern Italy) as part of the LIFE11 ECOREMED project, funded by the European Commission, to test innovative agriculture-based soil restoration techniques. These sites have been selected because they have been used for the temporary storage of urban and building waste (Teverola), subject to illicit dumping of unknown material (Trentola-Ducenta), or suspected to be polluted by metals due to agricultural practices (Giugliano). Chemical analysis of soil samples allowed the baseline pollution levels to be determined prior to any intervention. It was found that these areas can be considered contaminated for residential use, in accordance with Italian environmental law (Law Decree 152/2006). Statistical analysis applied to the data proved that average mean concentrations of heavy hydrocarbons could be as high as 140 mg/kg of dry soil with peaks of 700 mg/kg of dry soil, for the Trentola-Ducenta site; the median concentration of analytical results for hydrocarbon (HC) concentration for the Trentola-Ducenta and Giugliano sites was 63 and 73.4 mg/kg dry soil, respectively; for Teverola, the median level was 35 mg/kg dry soil. Some PAHs (usually benzo(a)pyrene) also exceeded the maximum allowed level in all sites. From the principal component analysis applied to PAH concentrations, it emerged that pollutants can be supposed to derive from a single source for the three sites. Diagnostic ratios calculated to determine possible PAH sources suggest petroleum combustion or disposal practice. Our sampling protocol also showed large dishomogeneity in soil pollutant spatial distribution, even at a scale as small as 3.3 m, indicating that variability could emerge at very short spatial scales.
اظهر المزيد [+] اقل [-]Influence of advections of particulate matter from biomass combustion on specific-cause mortality in Madrid in the period 2004–2009 النص الكامل
2015
Linares, C. | Carmona, R. | Tobías, A. | Mirón, I. J. | Díaz, J.
Approximately, 20 % of particulate and aerosol emissions into the urban atmosphere are of natural origin (including wildfires and Saharan dust). During these natural episodes, PM₁₀and PM₂.₅levels usually exceed World Health Organisation (WHO) health protection thresholds. This study sought to evaluate the possible effect of advections of particulate matter from biomass fuel combustion on daily specific-cause mortality among the general population and the segment aged ≥75 years in Madrid. Ecological time-series study in the city of Madrid from January 01, 2004 to December 31, 2009. The dependent variable analysed was daily mortality due to natural (ICD-10:A00-R99), circulatory (ICD-10:I00-I99), and respiratory (ICD-10:J00-J99) causes in the population, both general and aged ≥75 years. The following independent and control variables were considered: a) daily mean PM₂.₅and PM₁₀concentrations; b) maximum daily temperature; c) daily mean O₃and NO₂concentrations; d) advection of particulate matter from biomass combustion (http://www.calima.ws/), using a dichotomous variable and e) linear trend and seasonalities. We conducted a descriptive analysis, performed a test of means and, to ascertain relative risk, fitted a model using autoregressive Poisson regression and stratifying by days with and without biomass advection, in both populations. Of the 2192 days analysed, biomass advection occurred on 56, with mean PM₂.₅and PM₁₀values registering a significant increase during these days. PM₁₀had a greater impact on organic mortality with advection (RRall ages = 1.035 [1.011–1.060]; RR ≥ 75 years = 1.066 [1.031–1.103]) than did PM₂.₅without advection (RRall ages = 1.017 [1.009–1.025]; RR ≥ 75 years = 1.012 [1.003–1.022]). Among specific causes, respiratory—though not circulatory—causes were associated with PM₁₀on days with advection in ≥75 year age group. PM₁₀, rather than PM₂.₅, were associated with an increase in natural cause mortality on days with advection of particulate matter from biomass combustion, particularly in the ≥75 year age group.
اظهر المزيد [+] اقل [-]Fuel nitrogen conversion and release of nitrogen oxides during coal gangue calcination النص الكامل
2015
Zhang, Yingyi | Ge, Xinlei | Liu, Lili | Wang, Xidong | Zhang, Zuotai
The pollution emission during the widespread utilization of coal gangue in construction industry has long been neglected. In present study, the NO ₓ release behaviors in a simulation experiment of coal gangue calcination in construction industry were systematically investigated. The corresponding evolution of nitrogen functionalities in coal gangue was also discussed. Results showed that pyrrolic (N-5) and pyridine N-oxide (N-6-O) forms nitrogen were relatively abundant in the raw gangue. During calcination, the N-5 and N-6-O form nitrogen greatly decreased and converted to quaternary nitrogen (N-Q). It was found that NO₂was formed under slowly heating-up condition and at 600 °C under isothermal condition, while only NO was detected with further increase of temperature. From 600 to 1000 °C, the conversion ratio of fuel nitrogen to NO ₓ increased from 8 to 12 %. The char nitrogen was found greatly contribute to NO formation, which may bring difficulty to the abatement of NO ₓ emission during coal gangue calcination.
اظهر المزيد [+] اقل [-]Effect of cadmium stress and inoculation with a heavy-metal-resistant bacterium on the growth and enzyme activity of Sorghum bicolor النص الكامل
2015
Muratova, Anna | Lyubun, Yelena | German, Kristina | Turkovskaya, Olga
In this study, the influence of the heavy-metal-resistant rhizobacterial inoculant Rhodococcus ruber N7 on the growth and enzyme activity of Sorghum bicolor (L.) Moench. under cadmium stress was investigated in quartz sand pot experiments. The effect of cadmium and bacterium on the plant biomass accumulation, photosynthetic pigments, protein content, and the activities of plant-tissue enzymes such as peroxidase, laccase, and tyrosinase were estimated. It was shown that the presence of cadmium in the sand influenced the roots to a greater extent than it influenced the aerial parts of sorghum. This is manifested as increased protein content, reduced activity of peroxidase, and increased activity of laccase. Compared with cadmium stress, inoculation of plants with rhizobacterium R. ruber N7 has a stronger (and often opposite) effect on the biochemical parameters of sorghum, including a decrease in the concentration of protein in the plant, but increased the activity of peroxidase, laccase, and tyrosinase. Under cadmium contamination of sand, R. ruber N7 successfully colonizes the roots of Sorghum bicolor, survives in its root zone, and contributes to the accumulation of the metal in the plant roots, thereby reducing the concentration of the pollutant in the environment.
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