خيارات البحث
النتائج 1901 - 1910 من 3,208
Estimated human excretion rates of natural estrogens calculated from their concentrations in raw municipal wastewater and its application النص الكامل
2015
Liu, Ze-hua | Lu, Gui-ning | Yin, Hua | Dang, Zhi
Natural estrogens are important endocrine disrupting compounds (EDCs), which may pose adverse effects on our environment. To avoid time-consuming sample preparation and chemical analysis, estimation of their concentrations in municipal wastewater based on their human urine/feces excretion rates has been generally adopted. However, the data of excretion rates available are very limited and show significant difference among countries. In the context of increasing reporting on the concentrations of natural estrogens in municipal wastewater around the world, this study presented a simple method to estimate their human excretion rates based on the concentrations of natural estrogens in raw sewage. The estimated human excretion rates of natural estrogens among ten countries were obtained, which totally covered over 33 million population. Among these, Brazilians had the largest excretion rates with estrone (E1) and 17β-estradiol (E2) as 236.9 and 60 μg/day/P, respectively, while Iran had the lowest value of 2 μg/day/P for E1 and 0.5 μg/day/P for E2. The average estimated human excretion rates of E1, E2, and estriol (E3) are 17.3, 6.4, and 39.7 μg/day/P, respectively. When the estimated human excretion rates obtained were applied for prediction, the predicted results showed better accuracies than those based on human urinary/feces excretion rates. The method in this study is simple, cost-effective and time-saving, which may be widely applied.
اظهر المزيد [+] اقل [-]Potentially toxic element phytoavailability assessment in Technosols from former smelting and mining areas النص الكامل
2015
Qasim, Bashar | Motelica-Heino, Mikael | Joussein, Emmanuel | Soubrand, Marilyne | Gauthier, Arnaud
This study reports the chemical bioavailability of several potentially toxic elements (Zn, Pb, Cd, As, and Sb) in contaminated Technosols from two former smelting and mining areas. Though these elements have long been recognized as potentially harmful elements, understanding of their toxicity and environmental behavior in Technosols developed on former mining and smelting sites are more limited, particularly for As and Sb. Surface soils were sampled from metallophyte grassland contaminated with Zn, Pb, and Cd located at Mortagne-du-Nord (North France) and from a former mining settling basin contaminated with As, Pb, and Sb located at la Petite Faye (Limoges, France). Various selective single extraction procedures (CaCl₂, NaNO₃, NH₄NO₃, DTPA, and EDTA) were used together with germination tests with dwarf beans whose shoots were analyzed for their potentially toxic element concentrations after 21 days of growth. The extraction capacity of the potentially toxic elements followed the order EDTA > DTPA > NH₄NO₃ > CaCl₂ > NaNO₃for both studied areas. Pearson’s correlation coefficient analysis between the concentrations of potentially toxic elements accumulated in bean primary leaves or their mineral mass with their extractable concentrations showed a positive significant correlation with dilute CaCl₂and nitrate solutions extraction procedures. In contrast, for all studied elements, except Pb, the complexing and chelating extractants (EDTA and DTPA) exhibited poor correlation with the dwarf bean leaves concentrations. Moreover, results showed that the 0.01 M CaCl₂extraction procedure was the most suitable and provided the most useful indications of metal phytoavailability for studied elements.
اظهر المزيد [+] اقل [-]Spatial distribution and toxicity assessment of heavy metals in sediments of Liaohe River, northeast China النص الكامل
2015
He, Yan | Meng, Wei | Xu, Jian | Zhang, Yuan | Liu, Sisi | Guo, Changsheng
Twenty-four surface sediment samples were collected from Liaohe River in June 2014 for the analysis of total concentrations of Cu, Pb, Zn, Cd, Ni, Fe, and Mn. The spatial distribution of heavy metals in Liaohe River was site specific, with Hun River as the most polluted river mainly affected by industrial and human activities. The contents of acid-volatile sulfide (AVS) and simultaneously extracted metals (SEMs) in Liaohe River varied significantly, ranging from 0.03 to 19.4 μmol/g and 0.14 to 10.8 μmol/g, respectively. Sulfate-reducing bacteria (SRB) community size, organic matter and sulfate availability, and sediment redox status may be the main factors affecting the AVS distribution. Among all the acid-extracted metals, Zn was dominant in all samples, whereas much more toxic Cd contributed less than 1.0 % to the total SEMs. Sediment quality guidelines (SQGs) and AVS-SEM models were used to predict the sediment toxicity. Results revealed that only a small portion of sites exhibited potential metal toxicity to aquatic biota, while adverse effects should rarely occur in majority of sites. Comparison of the two assessment methods showed inconsistent results, indicating that each method had its own limitations. The combination of different methods will be more convincing as to the sediment quality assessment.
اظهر المزيد [+] اقل [-]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.
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