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1.
Nature ; 574(7778): 353-358, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-31619795

RESUMEN

Since 2000, many countries have achieved considerable success in improving child survival, but localized progress remains unclear. To inform efforts towards United Nations Sustainable Development Goal 3.2-to end preventable child deaths by 2030-we need consistently estimated data at the subnational level regarding child mortality rates and trends. Here we quantified, for the period 2000-2017, the subnational variation in mortality rates and number of deaths of neonates, infants and children under 5 years of age within 99 low- and middle-income countries using a geostatistical survival model. We estimated that 32% of children under 5 in these countries lived in districts that had attained rates of 25 or fewer child deaths per 1,000 live births by 2017, and that 58% of child deaths between 2000 and 2017 in these countries could have been averted in the absence of geographical inequality. This study enables the identification of high-mortality clusters, patterns of progress and geographical inequalities to inform appropriate investments and implementations that will help to improve the health of all populations.


Asunto(s)
Mortalidad del Niño/tendencias , Mortalidad Infantil/tendencias , Niño , Geografía , Salud Global , Humanos , Lactante , Recién Nacido , Objetivos Organizacionales , Salud Pública , Factores Socioeconómicos , Naciones Unidas
2.
Int J Environ Health Res ; 34(2): 803-814, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36709497

RESUMEN

Per- and polyfluoroalkyl substances (PFASs) such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are environmental contaminants with unfavorable impacts on human health and nature. This study aimed to determine the PFOA and PFOS concentration in water and fish samples from Karun, the largest river in Iran. According to the results, the PFOA and PFOS in water samples were 5.81-69.26 ng/L and not detected (n.d.)-35.12 ng/L, respectively. The dry season displayed higher concentrations in water samples than in the wet season. The maximum PFOS concentration measured was related to Barbus barbules sp. (27.89 ng/g). The human health risk assessment indicated minor risks (hazard ratio, HR < 1) from PFOA and PFOS through consuming contaminated drinking water and fish. Only HR value of PFOS in downstream area exceeded slightly 1.0, indicating potential health risk due to consumption of the river fish. Considering the average PFASs concentration, the risk quotients (RQs) showed low ecological risk.


Asunto(s)
Ácidos Alcanesulfónicos , Caprilatos , Agua Potable , Fluorocarburos , Contaminantes Químicos del Agua , Animales , Humanos , Irán , Fluorocarburos/toxicidad , Fluorocarburos/análisis , Medición de Riesgo , Peces , Contaminantes Químicos del Agua/toxicidad , Contaminantes Químicos del Agua/análisis
3.
Int J Environ Health Res ; 33(1): 71-82, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34781808

RESUMEN

Total petroleum hydrocarbons (TPHs) are common environmental pollutants in aquatic ecosystems that tend to adsorb onto the sediments. This study aimed to monitor the concentration and assessment of contamination level of TPHs in the sediments of Karun River and Bahmanshir estuary, which will eventually flow into the Persian Gulf. GIS-mapping technique was used to indicate the distribution of TPHs. The samples were collected during dry and wet seasons at 15 monitoring stations. - The maximum amount of TPHs was obtained at station No. 14 in the dry season (225.29 µg/g). The indices of determining the pollution source showed that hydrocarbons in polluted areas were mainly of biogenic origin. Compared to sediment quality guidelines (SQGs) and contamination factor (Cf), the study area sediments were in the conditions of moderate pollution and had a low ecological risk.


Asunto(s)
Petróleo , Hidrocarburos Policíclicos Aromáticos , Contaminantes Químicos del Agua , Estaciones del Año , Ecosistema , Ríos , Irán , Monitoreo del Ambiente , Contaminantes Químicos del Agua/análisis , Sedimentos Geológicos , Hidrocarburos/análisis , Hidrocarburos Policíclicos Aromáticos/análisis , Medición de Riesgo
4.
Bull Environ Contam Toxicol ; 110(1): 39, 2023 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-36625942

RESUMEN

This study aimed to assess 13 PAHs concentrations and induced human and ecological risks in seawater and surficial sediments of eight estuaries in the northern coastline of the Persian Gulf, Iran, 2021. The range of Σ13 PAHs concentration was 0.24-8.83 µg L-l and 3.1-11.46 µg g-1 dry weight, and the mean value was 4.99 µg L-l and 6.06 µg g-1 dry weight in seawater and sediment, respectively. Two, three and four rings PAHs were dominant with 29.33% and 41.33% of ΣPAHs in seawater and sediment, respectively. The primary source of PAHs was both pyrolytic and petrogenic. Most PAHs' calculated health (DCR, HQs, TEF, MEF) and ecological risks (SQGs) values in seawater were in the moderate range or high-risk values for damage to the marine environment. It is concluded that the pollution of PAHs should be carefully considered, and the government should make a proper action plan to minimize the pollution.


Asunto(s)
Hidrocarburos Policíclicos Aromáticos , Contaminantes Químicos del Agua , Humanos , Sedimentos Geológicos , Hidrocarburos Policíclicos Aromáticos/análisis , Océano Índico , Contaminantes Químicos del Agua/análisis , Monitoreo del Ambiente , Agua de Mar
5.
Epilepsy Behav ; 126: 108479, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-34922328

RESUMEN

Hypochondroplasia is a skeletal dysplasia syndrome with an autosomal dominant inheritance. It may be associated with temporal lobe epilepsy. We present a series of four patients (two female, two male) with hypochondroplasia who presented at our center with drug refractory epilepsy. Clinical details and EEG and MRI findings led to a diagnosis of temporal lobe epilepsy in all four cases. The MRI findings indicate the epilepsy in hypochondroplasia may be associated with bilateral temporal lobe dysgenesis.


Asunto(s)
Enanismo , Epilepsia del Lóbulo Temporal , Huesos/anomalías , Electroencefalografía , Epilepsia del Lóbulo Temporal/complicaciones , Epilepsia del Lóbulo Temporal/diagnóstico por imagen , Femenino , Humanos , Deformidades Congénitas de las Extremidades , Lordosis , Imagen por Resonancia Magnética , Masculino , Mutación , Receptor Tipo 3 de Factor de Crecimiento de Fibroblastos/genética
6.
Atmos Environ (1994) ; 261: 118563, 2021 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-34177342

RESUMEN

The limited knowledge about the mechanism of SARS-CoV-2 transmission is a current challenge on a global scale. Among possible transmission routes, air transfer of the virus is thought to be prominent. To investigate this further, measurements were conducted at Razi hospital in Ahvaz, Iran, which was selected to treat COVID-19 severe cases in the Khuzestan province. Passive and active sampling methods were employed and compared with regard to their efficiency for collection of airborne SARS-COV-2 virus particles. Fifty one indoor air samples were collected in two areas, with distances of less than or equal to 1 m (patient room) and more than 3 m away (hallway and nurse station) from patient beds. A simulation method was used to obtain the virus load released by a regularly breathing or coughing individual including a range of microdroplet emissions. Using real-time reverse transcription polymerase chain reaction (RT-PCR), 11.76% (N = 6) of all indoor air samples (N = 51) collected in the COVID-19 ward tested positive for SARS-CoV-2 virus, including 4 cases in patient rooms and 2 cases in the hallway. Also, 5 of the 6 positive cases were confirmed using active sampling methods with only 1 based on passive sampling. The results support airborne transmission of SARS-CoV-2 bioaerosols in indoor air. Multivariate analysis showed that among 15 parameters studied, the highest correlations with PCR results were obtained for temperature, relative humidity, PM levels, and presence of an air cleaner.

7.
J Environ Manage ; 280: 111851, 2021 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-33360551

RESUMEN

Wastewater treatment plant (WWTP) is one of the significant sources of Microplastics (MPs) release to the environment. Di 2-ethyl hexyl phthalate (DEHP) is used as an additive for more flexibility of plastics. In this study, we determined the number, size, shape, and color distribution of MPs as well as the concentration of DEHP in MPs and wastewater during the wastewater treatment process in WWTP. Samples were collected from 4 stations of different treatment stages of WWTP. The microplastic particles and the concentration of DEHP were detected via the fluorescence and polarized light microscopy and GC/MS instrument, respectively. The number of MPs decreased from 9.2 (station 1) to 0.84 MP/L (the final treated effluent) during the wastewater treatment process. Also, the size of MPs at the last station was smaller than the other stations. The mean concentrations of DEHP in MPs in stations 1, 2, 3 and 4 had the respective values of 83.3, 61.05, 30.62 and 17.49 µg/g, while the mean concentrations of DEHP in wastewater in stations 1, 2, 3 and 4 were 30.08, 25.07, 9.56, and 8.13 µg/L, respectively. This study shows that despite the removal of high amounts of MPs and DEHP in the final effluent of WWTP, due to the high volume of this effluent (2.828 × 108 L/d), significant amount of MPs (2.419 × 107 MP/day) and DEHP enter the aquatic environment daily, which may threaten the health of the fish and aquatic organisms and ultimately on the health of the local population.


Asunto(s)
Contaminantes Químicos del Agua , Purificación del Agua , Animales , Monitoreo del Ambiente , Microplásticos , Ácidos Ftálicos , Plásticos , Eliminación de Residuos Líquidos , Aguas Residuales , Contaminantes Químicos del Agua/análisis
8.
Water Sci Technol ; 83(3): 567-579, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33600362

RESUMEN

In this study, hematite nanoparticles (HNPs) were used as the persulfate (PS) activator for the sonocatalytic degradation of bisphenol A (BPA). The physicochemical properties of the synthesized HNPs were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The effect of different operational parameters (pH, nanoparticle dosage, persulfate concentration, and ultrasonic power) on catalytic activity were evaluated. The BPA degradation rate was improved when ultrasonic (US) irradiation was used simultaneously with HNPs for activating PS. According to the results, 98.94% of BPA (10 mg/L) was degraded within 15 min of reaction time at 4 mM persulfate and 0.01 g/L HNPs under ultrasonic irradiation of 250 W. The degree of mineralization of BPA was measured using chemical oxygen demand (COD), and 36.98% was achieved under optimum conditions. Quenching tests were done using different scavenger compounds; these showed that both hydroxyl and sulfate radicals were reactive species in BPA degradation. According to the results of reusability tests, the degradation efficiency decreased to 86.34%, indicating that HNPs can be recycled several times. All of the anions tested, but mainly hydrogen phosphate, had an inhibitory effect on BPA degradation. The results showed that the US/HNPs/PS process is effective for the degradation of the organic pollutants.


Asunto(s)
Nanopartículas Magnéticas de Óxido de Hierro , Contaminantes Químicos del Agua , Compuestos de Bencidrilo , Fenoles , Contaminantes Químicos del Agua/análisis
9.
J Res Med Sci ; 26: 45, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34484377

RESUMEN

BACKGROUND: Migraine patients often have painful trigger points, especially in the area of head and neck. Thus, we aimed to investigate the effect of myofascial release and stretching techniques in the management of migraine headache. MATERIALS AND METHODS: This was a randomized controlled trial study on 40 migraine patients. The subjects in the experimental group received three sessions with a duration of 20 min per session techniques. Databases were analyzed using 2 × 3 repeated-measures analyses of variance (P < 0.05). RESULTS: Experimental group showed a significant reduction in pain intensity (P < 0.001) and the neck disability index score (P < 0.001) and an increase in cervical range of motion (P < 0.001) in all time points after the intervention as compared with baseline and control group (P < 0.001). CONCLUSION: Myofascial release and stretching techniques were effective in improving symptoms in patients with migraine headache.

10.
Cell Mol Biol (Noisy-le-grand) ; 64(1): 91-96, 2018 01 31.
Artículo en Inglés | MEDLINE | ID: mdl-29412800

RESUMEN

Organ transplantation is an effective process that prolongs the lives of individuals suffering from incapacitating conditions. The aim of this study was to evaluate the view point of medical students in Iran regarding ethical aspects and knowledge on organ transplantation and donation. The participants included 165 medical students from different faculties of Shahid Beheshti University of Medical Sciences, Tehran, Iran. They were assessed using a reliable questionnaire that examined their ethical aspects and knowledge regarding organ transplantation and donation. All data analyses were performed using Chi-square and analysis of variance tests with SPSS software. Results showed that main sources of respondents' knowledge on organ transplantation and donation were TV, 51.52 % (n = 85) and Internet, 19.39 % (n = 32). 91.51% (n = 151) of the respondents understand and 8.48% (n =14) do not understand the concept of brain death. 49.69% (n = 82) of the respondents were willing to donate their organs. A brain death donor was selected by respondents as the best option for organs transplantation (72.12%; n = 119). The respondents selected young patients as the preferred recipients of an organ (69.69%; n = 115). There was no correlation between gender, age, educational level, marital status and attitude towards organ transplantation. From the results, there is need for an organized educational planning for medical students in ethical issue and knowledge on organ and tissue transplantation.


Asunto(s)
Trasplante de Órganos , Donantes de Tejidos , Adulto , Femenino , Conocimientos, Actitudes y Práctica en Salud , Humanos , Irán , Masculino , Trasplante de Órganos/ética , Donantes de Tejidos/ética , Adulto Joven
11.
Ecotoxicol Environ Saf ; 158: 171-181, 2018 Aug 30.
Artículo en Inglés | MEDLINE | ID: mdl-29684747

RESUMEN

Human impact on the environment leads to the release of many pollutants that produce artificial compounds, which can have harmful effects on the body's endocrine system; these are known as endocrine disruptors (EDs). Nonylphenol (NP) is a chemical compound with a nonyl group that is attached to a phenol ring. NP-induced H2AX is a sensitive genotoxic biomarker for detecting possible DNA damage; it also causes male infertility and carcinogenesis. We attempt to comprehensively review all the available evidence about the different ways with descriptive mechanisms for explaining the possible DNA damage that is induced by NP. We systematically searched several databases, including PubMed, Scopus, Web of Science, and gray literature, such as Google Scholar by using medical subheading (MeSH) terms and various combinations of selected keywords from January 1970 to August 2017. The initial search identified 62,737 potentially eligible studies; of these studies, 33 were included according to the established inclusion criteria. Thirty-three selected studies, include the topics of animal model (n = 21), cell line (n = 6), human model (n = 4), microorganisms (n = 1), solid DNA (n = 1), infertility (n = 4), apoptosis (n = 6), and carcinogenesis (n = 3). This review highlighted the possible deleterious effects of NP on DNA damage through the ability to produce ROS/RNS. Finally, it is significant to observe caution at this stage with the continued use of environmental pollutants such as NP, which may induce DNA damage and apoptosis.


Asunto(s)
Daño del ADN/efectos de los fármacos , Fenoles/toxicidad , Animales , Apoptosis/efectos de los fármacos , Línea Celular , Modelos Animales de Enfermedad , Disruptores Endocrinos/toxicidad , Contaminantes Ambientales/toxicidad , Humanos , Infertilidad Masculina/inducido químicamente , Infertilidad Masculina/diagnóstico , Masculino
12.
J Environ Manage ; 228: 32-39, 2018 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-30212672

RESUMEN

In this study a novel hybrid process was employed for the degradation of Metanil Yellow (MY). The operational parameters of photoelectro-peroxone/zero valent iron (PEP/ZVI) process were studied and the complete decoloration was found at pH = 3.0, 100 mg/L ZVI, 33.2 mg/L ozone, 300 mA applied current and 25 min reaction time. The combination of UV, ozone, electrogenerated H2O2 and ZVI showed high synergistic effect for MY degradation. ZVI showed high reusability in PEP/ZVI process. Among anions, nitrite ion demonstrated high inhibitory effect while chloride ions had no significant effect on MY degradation. Scavenging tests depicted that hydroxyl radical and singlet oxygen were the main agents of MY degradation. PEP/ZVI process was tested for several emerging pollutants (benzotriazole, 4-chlorophenol, carmoisine and tetracycline); the results presented the effectiveness of the process for the degradation of pollutants in a way that complete degradation occurred at only 30 min. Moreover, the performance of PEP/ZVI was examined for the treatment of two actual wastewaters. PEP/ZVI demonstrated an excellent function in terms of the removal of organic compounds to achieve discharging standards.


Asunto(s)
Ácidos Sulfúricos/química , Aguas Residuales/química , Contaminantes Químicos del Agua/química , Estudios de Factibilidad , Peróxido de Hidrógeno/química , Concentración de Iones de Hidrógeno , Cinética , Procesos Fotoquímicos
13.
J Res Med Sci ; 23: 37, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29887905

RESUMEN

BACKGROUND: In this study, we aimed to evaluate the effectiveness of extracorporeal shockwave treatment (ESWT) on pain and ankle-hindfoot scale of the American Orthopedic Foot and Ankle Society (AOFAS) score of patients with chronic Achilles tendinopathy (AT). MATERIALS AND METHODS: In this double-blind clinical trial, 43 patients with chronic AT were selected and randomly allocated in two groups to receive a basic treatment with ESWT or sham SWT (radial and focused shock waves, four sessions once a week for 4 weeks). AOFAS and pain scores for each patient were recorded at baseline (before intervention), immediately after intervention, and 4 and 16 weeks after intervention using AOFAS and visual analog scale (VAS) scaling method. RESULTS: A total of 43 patients (22 ESWT and 21 sham SWT) were participated in this study. Both groups improved during the treatment and follow-up period. The mean VAS score decreased from 7.55 to 3 in the intervention group and from 7.70 to 4.30 in the sham SWT group. Mean AOFAS and VAS scores were significantly different between ESWT and no ESWT groups at 16 weeks of follow-up (P = 0.013) (P = 0.47). There was no significant difference in terms of AOFAS and VAS scores between both the groups in the other follow-up times. CONCLUSION: Overall, ESWT causes decrease in VAS score and increase in AOFAS score. However, due to the small sample size, the results were not statistically significant. It is recommended to plan more interventional studies with larger sample size in the future.

14.
J Environ Manage ; 204(Pt 1): 221-229, 2017 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-28888204

RESUMEN

High total dissolved solids (TDS) wastewater containing high amounts of organics with toxic and recalcitrant characteristics is a major concern in some petrochemical industries. This study was designed to evaluate a novel electrokinetic process for chemical oxygen demand (COD) removal. The removal of COD was carried out in some batch experiments in lab scale and effect of experimental factors such as the pH, current intensity, time, electrodes distances and TDS on the COD removal was evaluated. Also scale-up of the process was done in order to evaluate energy consumption. The obtained findings indicated that best conditions for COD removal were achieved in pH 5, current intensity of 0.5 A and electrodes distance of 2 cm. Pseudo-first-order kinetic model with rate constant of 0.0093 min-1 and significant coefficient of correlation (R2) 0.948 was the best fitted with experimental results. Energy consumption was 32 KWh.m-3 while 80 fold scaling up the reactor resulted in lower energy consumption of 2.1 KWh.m-3. Biodegradability improvement confirmed by BOD5/COD, average oxidation state (AOS) and carbon oxidation state (COS) indicators, Also GC chromatogram of the raw and treated wastewater showed removal and/or degradation of recalcitrant organics to more degradable and simpler compounds.


Asunto(s)
Análisis de la Demanda Biológica de Oxígeno/métodos , Cloruro de Sodio/química , Aguas Residuales/química , Biodegradación Ambiental , Electrodos , Residuos Industriales , Oxidación-Reducción
15.
J Environ Manage ; 187: 111-121, 2017 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-27888712

RESUMEN

This study was performed to assess the efficiency of silica nanopowder (SNP)/milk vetch-derived charcoal (MVDC) nanocomposite coupled with the ultrasonic irradiation named sono-adsorption process for treating water-contained Basic Red 46 (BR46) dye. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and Fourier transform infrared spectroscopy (FT-IR) were performed for the characterization of as-prepared adsorbent. The sono-assisted adsorption process was optimized using response surface optimization on the basis of central composite design by the application of quadratic model. Accordingly, the color removal can be retained more than 93% by an initial BR46 concentration of 8 mg/L, sonication time of 31 min, adsorbent dosage of 1.2 g/L and initial pH of 9. The pseudo-second order kinetic model described the sono-assisted adsorption of BR46 reasonably well (R2 > 0.99). The intra-particular diffusion kinetic model pointed out that the sono-assisted adsorption of BR46 onto SNP/MVDC nanocomposite was diffusion controlled as well as that ultrasonication enhanced the diffusion rate.


Asunto(s)
Planta del Astrágalo/química , Compuestos Azo/aislamiento & purificación , Colorantes/aislamiento & purificación , Nanocompuestos/química , Contaminantes Químicos del Agua/aislamiento & purificación , Adsorción , Compuestos Azo/química , Carbón Orgánico/química , Colorantes/química , Difusión , Concentración de Iones de Hidrógeno , Cinética , Modelos Teóricos , Dióxido de Silicio/química , Espectroscopía Infrarroja por Transformada de Fourier , Industria Textil , Ultrasonido/métodos , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/química , Difracción de Rayos X
16.
J Environ Manage ; 191: 198-208, 2017 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-28104552

RESUMEN

Treatment of a saline petrochemical wastewater with BOD5/COD ratio of less than 0.1 was investigated using a consortium consisted of three isolated salt-tolerant bacteria namely, Kocuria turfanesis, Halomonas alkaliphila and Pseudomonas balearica. Selected bacteria were isolated from petrochemical wastewater containing mineral salt mediums of 3% salinity. A lab-scale activated sludge bioreactor was used for startup in batch mode operation and after obtaining the MLSS concentration of about 3000 mg/L, the operation was changed to continuous flow mode to determine the biokinetic coefficients under different organic loading rates of 0.33-1.21 kg CODm-3 d-1. The COD removal efficiency of 78.7%-61.5% was observed for treatment of real saline wastewater with a decreasing trend along with increasing the organic loading rate. In addition, results of kinetic investigation demonstrated that the yield(Y), endogenous decay coefficient (kd), maximum reaction rate (Kmax), maximum specific growth rate (µmax) and saturation constant (Ks) were 0.54 mg VSS mg COD-1, 0.014 day-1, 1.23 day-1, 0.66 day-1, and 1315 mg L-1, respectively.


Asunto(s)
Biodegradación Ambiental , Aguas Residuales , Reactores Biológicos/microbiología , Aguas del Alcantarillado , Cloruro de Sodio , Eliminación de Residuos Líquidos
17.
J Environ Manage ; 186(Pt 1): 55-63, 2017 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-27852522

RESUMEN

Photocatalytic degradation of tetracycline using MWCNT/TiO2nanocomposite was investigated under UVC irradiation. The effective operational parameters included pH, irradiation time, photocatalyst dosage, weight ratio of MWCNT to TiO2 and tetracycline concentration and were studied consecutively. Complete removal of tetracycline concentrations of up to 10 mg/L was obtained at MWCNT to TiO2 ratio of 1.5 (w/w%), pH 5, photocatalyst dosage of 0.2 g/L. Pseudo-first order kinetic model was best fitted with the experimental results (R2: 0.91-0.98 for different tetracycline concentrations). Based on TOC analysis, mineralization was 37% in the same reaction conditions for initial tetracycline concentration of 10 mg/L and reached to 83% after 300 min. In the case of real pharmaceutical wastewater, the COD concentration of 2267 mg/L decreased to 342 mg/L after 240 min in the same operational conditions.


Asunto(s)
Nanocompuestos/química , Tetraciclina/química , Titanio/química , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/química , Catálisis , Concentración de Iones de Hidrógeno , Cinética , Nanotubos de Carbono/química , Procesos Fotoquímicos , Fotólisis , Rayos Ultravioleta , Aguas Residuales/química
18.
Environ Manage ; 59(5): 826-841, 2017 05.
Artículo en Inglés | MEDLINE | ID: mdl-28101588

RESUMEN

Better understanding of the factors controlling sediment load at a catchment scale can facilitate estimation of soil erosion and sediment transport rates. The research summarized here enhances understanding of correlations between potential control variables on suspended sediment loads. The Soil and Water Assessment Tool was used to simulate flow and sediment at the Ankara River basin. Multivariable regression analysis and principal component analysis were then performed between sediment load and controlling variables. The physical variables were either directly derived from a Digital Elevation Model or from field maps or computed using established equations. Mean observed sediment rate is 6697 ton/year and mean sediment yield is 21 ton/y/km² from the gage. Soil and Water Assessment Tool satisfactorily simulated observed sediment load with Nash-Sutcliffe efficiency, relative error, and coefficient of determination (R²) values of 0.81, -1.55, and 0.93, respectively in the catchment. Therefore, parameter values from the physically based model were applied to the multivariable regression analysis as well as principal component analysis. The results indicate that stream flow, drainage area, and channel width explain most of the variability in sediment load among the catchments. The implications of the results, efficient siltation management practices in the catchment should be performed to stream flow, drainage area, and channel width.


Asunto(s)
Sedimentos Geológicos/análisis , Ríos , Modelos Teóricos , Análisis de Componente Principal , Análisis de Regresión , Suelo , Turquía
19.
Water Sci Technol ; 2017(1): 36-47, 2017 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-29698219

RESUMEN

Metronidazole (MNZ) is a major threat to the ecosystems and human health, due to its toxicity and carcinogenic nature. The main aim of this study was to evaluate the efficiency of graphene oxide functionalized ß-cyclodextrin/Ag nanocomposite (GO/ß-CD/Ag) for MNZ removal from aqueous solution. The effect of operational parameters such as solution pH (2-5), adsorbent dosages (0.2-1 g/L), contact time (10-80 min), initial MNZ concentrations (0.25-10 mg/L) and ionic strength (0.001-0.1 mol/L) was studied using Taguchi experimental design. The maximum removal efficiency of 93.5% was observed for optimum conditions. The optimum values of contact time, the initial MNZ concentration, the ionic strength, the adsorbent dosage and solution pH were found to be 20 min, 0.25 ppm, 0.01 mol/L, 0.4 g/L and 2, respectively. Freundlich and Dubinin-Radushkevich isotherm models were best-fitted with experimental data. Pseudo-first order and type 1 pseudo-second order kinetic models showed the maximum correlation with the experimental data. Adsorption experiments with real samples indicated that the adsorptive removal of MNZ from a hospital wastewater was 72%. Desorption studies showed maximum recovery of GO/ß-CD/Ag nanocomposite during three cycles. According to the obtained results, it can be concluded that the application of carbon adsorbents such as GO/ß-CD/Ag can be considered an efficient method for final treatment of effluents containing antibiotics.


Asunto(s)
Grafito/química , Metronidazol/química , Nanocompuestos/química , Plata/química , Contaminantes Químicos del Agua/química , beta-Ciclodextrinas/química , Adsorción , Antiinfecciosos/química , Carbono , Concentración de Iones de Hidrógeno , Cinética , Concentración Osmolar , Agua , Purificación del Agua/métodos
20.
Environ Monit Assess ; 189(2): 50, 2017 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-28058613

RESUMEN

Tigris and Euphrates river basin (TERB) is one of the largest river basins in the Middle East, and the precipitation (in the form of snowfall) is a major source of streamflow. This study investigates the spatial and temporal variability of precipitation and streamflow in TERB to better understand the hydroclimatic variables and how they varied over time. The precipitation shows a decreasing trend with 1980s being wetter and 2000s being drier. A total of 55 and 40% reduction in high flows in Tigris and Euphrates rivers at T20 and E3 was seen in post-reservoir period. A lag time of 3 to 4 and 5 to 6 months was estimated between peak snowfall and runoff time periods. Decreasing precipitation and streamflow along with several planned dams could hamper the sustainability of several Mesopotamian marshlands that completely depend on the water from the Tigris and Euphrates rivers.


Asunto(s)
Clima , Monitoreo del Ambiente , Ríos , Nieve , Movimientos del Agua , Humedales , Mesopotamia , Medio Oriente , Abastecimiento de Agua
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