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Results 1631-1640 of 2,459
Estimated crop yield losses due to surface ozone exposure and economic damage in India
2014
Debaje, S. B.
In this study, we estimate yield losses and economic damage of two major crops (winter wheat and rabi rice) due to surface ozone (O₃) exposure using hourly O₃concentrations for the period 2002–2007 in India. This study estimates crop yield losses according to two indices of O₃exposure: 7-h seasonal daytime (0900–1600 hours) mean measured O₃concentration (M7) and AOT40 (accumulation exposure of O₃concentration over a threshold of 40 parts per billion by volume during daylight hours (0700–1800 hours), established by field studies. Our results indicate that relative yield loss from 5 to 11 % (6–30 %) for winter wheat and 3–6 % (9–16 %) for rabi rice using M7 (AOT40) index of the mean total winter wheat 81 million metric tons (Mt) and rabi rice 12 Mt production per year for the period 2002–2007. The estimated mean crop production loss (CPL) for winter wheat are from 9 to 29 Mt, account for economic cost loss was from 1,222 to 4,091 million US$ annually. Similarly, the mean CPL for rabi rice are from 0.64 to 2.1 Mt, worth 86–276 million US$. Our calculated winter wheat and rabi rice losses agree well with previous results, providing the further evidence that large crop yield losses occurring in India due to current O₃concentration and further elevated O₃concentration in future may pose threat to food security.
Show more [+] Less [-]Effects of ammonia on methane oxidation in landfill cover materials
2014
Long, Yu-Yang | Liao, Yan | Miao, Jing-Yu | Shen, Dong-Sheng
The effects of ammonia (NH₃) on CH₄attenuation in landfill cover materials consisting of landfill cover soil (LCS) and aged municipal solid waste (AMSW), at different CH₄concentrations, were investigated. The CH₄oxidation capacities of LCS and AMSW were found to be significantly affected by the CH₄concentration. The maximum oxidation rates for LCS and AMSW were obtained at CH₄concentrations of 5 % and 20 %(v/v), respectively, within 20 days. CH₄biological oxidation in AMSW was significantly inhibited by NH₃at low CH₄concentrations (5 %, v/v) but highly stimulated at high levels (20 % and 50 %, v/v). Oxidation in LCS was stimulated by NH₃at all CH₄concentrations due to the higher conversion of the nitrogen in NH₃in AMSW than in LCS. NH₃increases CH₄oxidation in landfill cover materials.
Show more [+] Less [-]Dissipation of available benzo[a]pyrene in aging soil co-contaminated with cadmium and pyrene
2014
Wang, Kai | Chen, Xin-xin | Zhu, Zhi-qiang | Huang, Hua-gang | Li, Ting-qiang | Yang, Xiao-e
A microcosm experiment was conducted to investigate the dissipation of available benzo[a]pyrene (BaP) in soils co-contaminated with cadmium (Cd) and pyrene (PYR) during aging process. The available residue of BaP in soil was separated into desorbing and non-desorbing fractions. The desorbing fraction contributed more to the dissipation of available BaP than the non-desorbing fraction did. The concentration of bound-residue fraction of BaP was quite low across all treatments. Within the duration of this study (250 days), transformation of BaP from available fractions to bound-residue fraction was not observed. Microbial degradation was the dominant mechanism of the dissipation of available BaP in the soil. The dissipation of available BaP was significantly inhibited with the increment in Cd level in the soil. The addition of PYR (250 mg kg⁻¹) remarkably promoted the dissipation of available BaP without reducing Cd availability in the soil. The calculated half-life of available BaP in the soil prolonged with the increment in Cd level; however, the addition of PYR shortened the half-life of available BaP by 13.1, 12.7, and 32.8 % in 0.44, 2.56, and 22 mg Cd kg⁻¹soils, respectively. These results demonstrated that the inhibiting effect of Cd and the promoting effect of PYR on the dissipation of available BaP were competitive. Therefore, this study shows that the bioremediation process of BaP can be more complicated in co-contaminated soils.
Show more [+] Less [-]Anodic oxidation of benzoquinone using diamond anode
2014
Panizza, Marco
The anodic degradation of 1,4-benzoquinone (BQ), one of the most toxic xenobiotic, was investigated by electrochemical oxidation at boron-doped diamond anode. The electrolyses have been performed in a single-compartment flow cell in galvanostatic conditions. The influence of applied current (0.5–2 A), BQ concentration (1–2 g dm⁻³), temperature (20–45 °C) and flow rate (100–300 dm³ h⁻¹) has been studied. BQ decay kinetic, the evolution of its oxidation intermediates and the mineralization of the aqueous solutions were monitored during the electrolysis by high-performance liquid chromatograph (HPLC) and chemical oxygen demand (COD) measurements. The results obtained show that the use of diamond anode leads to total mineralization of BQ in any experimental conditions due to the production of oxidant hydroxyl radicals electrogenerated from water discharge. The decay kinetics of BQ removal follows a pseudo-first-order reaction, and the rate constant increases with rising current density. The COD removal rate was favoured by increasing of applied current, recirculating flow rate and it is almost unaffected by solution temperature.
Show more [+] Less [-]Treatment of Basic Red 29 dye solution using iron-aluminum electrode pairs by electrocoagulation and electro-Fenton methods
2014
Yavuz, Yusuf | Shahbazi, Reza | Koparal, A Savaş | Öğütveren, Ülker Bakır
The aim of this study is the treatment of Basic Red 29 (BR29) dye solution using hybrid iron-aluminum electrodes by electrocoagulation and electro-Fenton methods. The effect of current density, initial pH, supporting electrolyte, H₂O₂, and initial dye concentration on dye removal efficiency was investigated, and the best experimental conditions were obtained. Time-coarse variation of UV-Vis spectra and toxicity and chemical oxygen demand (COD) removal were also examined at the best experimental conditions. Both systems were found very successful for the removal of BR29 dye. The removal efficiency of >95 % for BR29 dye solution was reached easily in a short time. At the best experimental conditions, for the initial BR29 concentration of 100 mg/L, >95 % BR29 dye and 71.43 % COD removal were obtained after 20 and 40 min of electrolysis, respectively. Additionally, toxicity results for electro-Fenton treatment of 100 mg/L BR29 were also very promising. According to the results obtained, although electro-Fenton is more effective, both systems can be used successfully to treat textile wastewater including dyes.
Show more [+] Less [-]Association of serum lead and mercury level with cardiometabolic risk factors and liver enzymes in a nationally representative sample of adolescents: the CASPIAN-III study
2014
Poursafa, Parinaz | Ataee, Ehsan | Motlagh, Mohammad Esmaeel | Ardalan, Gelayol | Tajadini, Mohammad Hassan | Yazdi, Maryam | Kelishadi, Roya
This study aims to determine the difference of serum Pb and Hg levels in adolescents with or without metabolic syndrome (MetS) and the association of serum levels of these heavy metals with cardiometabolic risk factors and liver enzymes in Iranian adolescents. The study population consisted of 320 adolescents (160 with MetS and 160 healthy controls). The relationship between serum heavy metals and cardiometabolic risk factors was assessed by linear regression. The odds ratios (OR) of having metabolic syndrome across Pb and Hg quartiles were determined by multiple logistic regression analysis. The mean (SD) of Pb and Hg concentrations were higher in adolescents with MetS than in those without it (0.83 (0.27) and 0.17 (0.01) vs. 0.65 (0.15) and 0.10 (0.08) μg/L, P = 0.01 and 0.0001, respectively). Increase in serum Pb and Hg was associated with increase in some cardiometabolic risk factors. Among boys and girls, diastolic blood pressure (DBP), fasting blood glucose, total cholesterol (TC), triglycerides (TG), and alanine aminotransaminase increased significantly across quartiles of serum Pb. Among girls, SBP, DBP, TC, and TG had a significant increase across Hg quartiles. The corresponding figure among boys was significant for SBP, DBP, and TG. Higher quartiles of Pb increased the risk of having MetS (OR 95 % CI 3.10, 2.25–4.27), the corresponding figure was 2.03, 1.75–3.16, across Hg quartiles. Our study showed significant associations between serum Pb and Hg levels with cardiometabolic risk factors in adolescents. In future surveys, the role of potential confounders should be considered more extensively. The clinical significance of these findings needs to be confirmed in longitudinal studies. By considering the origins of chronic diseases from early life, controlling environmental pollutants should be considered as a health priority for primordial or primary prevention of noncommunicable diseases.
Show more [+] Less [-]Utilization of two invasive free-floating aquatic plants (Pistia stratiotes and Eichhornia crassipes) as sorbents for oil removal
2014
Yang, Xunan | Chen, Shanshan | Zhang, Renduo
Free-floating aquatic plants Pistia stratiotes and Eichhornia crassipes are well-known invasive species in the tropics and subtropics. The aim of this study was to utilize the plants as cost-effective and environmentally friendly oil sorbents. Multilevel wrinkle structure of P. stratiotes leaf (PL), rough surface of E. crassipes leaf (EL), and box structure of E. crassipes stalk (ES) were observed using the scanning electron microscope. The natural hydrophobic structures and capillary rise tests supported the idea to use P. stratiotes and E. crassipes as oil sorbents. Experiments indicated that the oil sorption by the plants was a fast process. The maximum sorption capacities for different oils reached 5.1–7.6, 3.1–4.8, and 10.6–11.7 g of oil per gram of sorbent for PL, EL, and ES, respectively. In the range of 5–35 °C, the sorption capacities of the plants were not significantly different. These results suggest that the plants can be used as efficient oil sorbents.
Show more [+] Less [-]Electrosorption and photocatalytic one-stage combined process using a new type of nanosized TiO2/activated charcoal plate electrode
2014
Ayoubi-Feiz, Baharak | Aber, Soheil | Khataee, Alireza | Alipour, Esmaeel
In the present study, an activated charcoal (AC) plate was prepared by physical activation method. Its surface was coated with TiO₂nanoparticles by electrophoretic deposition (EPD) method. The average crystallite size of TiO₂nanoparticles was determined approximately 28 nm. The nature of prepared electrode was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area measurement before and after immobilization. The electrosorption and photocatalytic one-stage combined process was investigated in degradation of Lanasol Red 5B (LR5B), and the effect of dye concentration, electrolyte concentration, pH, voltage, and contact time was optimized and modeled using response surface methodology (RSM) approach. The dye concentration of 30 mg L⁻¹, Na₂SO₄concentration of 4.38 g L⁻¹, pH of 4, voltage of 250 mV, and contact time of 120 min were determined as optimum conditions. Decolorization efficiency increased in combined process to 85.65 % at optimum conditions compared to 66.03 % in TiO₂/AC photocatalytic, 20.09 % in TiO₂/AC electrosorption, and 1.91 % in AC photocatalytic processes.
Show more [+] Less [-]Characteristics, sources, and transport of tetrabromobisphenol A and bisphenol A in soils from a typical e-waste recycling area in South China
2014
Huang, De-Yin | Zhao, Hai-Qing | Liu, Chuan-Ping | Sun, Cui-Xiang
We studied the tetrabromobisphenol A (TBBPA) and bisphenol A (BPA) patterns and their sources and transport in different land-use soils from Longtang, South China, a typical electronic waste recycling center. We also studied the reductive debromination of TBBPA in paddy soils. TBBPA and BPA concentrations (on a dry weight basis) were undetected–220 and 0.50–325 ng/g, respectively, and both increased, by similar factors, in the following order: pond sediments < paddy soils = vegetable soils < wasteland < dismantling sites < former open burning sites. BPA concentrations were higher than TBBPA concentrations in all six land-use soils, and they correlated significantly. TBBPA and BPA were transported through the soil profiles, being found at relatively high concentrations in soil 0–40 cm deep, but only at low concentrations in soil 40–80 cm deep. The surface soil concentrations appear to have been strongly affected by crude recycling activities, and former open burning and dismantling sites were the main point sources. The areas surrounding the open burning sites and dismantling sites have been contaminated not only by the dumping of waste residues but also by fly ash deposition, even though the agricultural soils are far from the point pollution sources. Some BPA in the soils is likely to be the reductive debromination product of TBBPA because the long rainy season promotes TBBPA transformation and because BPA can persist for a long time. Incubation experiments confirmed that TBBPA could be transformed into BPA and that BPA could accumulate in waterlogged paddy soils, and this may be why BPA concentrations were higher than TBBPA concentrations in the Longtang area.
Show more [+] Less [-]Concentrations of organochlorine pesticides and polychlorinated biphenyls in human serum and their relation with age, gender, and BMI for the general population of Bizerte, Tunisia
2014
Ben Hassine, Sihem | Hammami, Bechir | Ben Ameur, Walid | El Megdiche, Yassine | Barhoumi, Badriddine | El Abidi, Rached | Driss, Mohamed Ridha
Human serum samples (n = 113) from Bizerte, northern Tunisia, collected between 2011 and 2012 were analyzed for 8 organochlorine pesticides (OCPs) including p,p′-dichlorodiphenyltrichloroethane (DDT) and its metabolites, hexachlorobenzene (HCB), hexachlorocyclohexane isomers, dieldrin, and heptachlor and 12 polychlorinated biphenyls (PCBs) congeners. Concentrations of these residues in serum were determined by gas chromatography with electron capture detector and total cholesterol (CHOL) and triglycerides (TG) levels were evaluated by enzymatic colorimetric method. HCB, p,p′-DDE, PCB-138, PCB-153, and PCB-180, were the most abundant organochlorine compounds (OCs) detected in >95 % of the study subjects. The mean levels of p,p′-DDE and HCB in serum were 168.8 and 49.1 ng g⁻¹lipid, respectively. The sum PCBs concentrations ranged from 37.5 to 284.6 ng g⁻¹lipid in the samples, with mean and median value of 136.1 and 123.2 ng g⁻¹lipid, respectively. The PCB profile consisted of persistent congeners, such as PCB-138, PCB-153, and PCB-180 which contributed for approximately 82.7 % to the ∑PCBs. Statistical analysis showed that most OCs correlated significantly with age, considering all samples together or with gender differentiation. The present study shows that the levels of p,p′-DDE and ∑DDTs were significantly higher in females than in males (p < 0.05), while PCBs levels were significantly higher in male (p < 0.05) than in females. No statistically significant association was found between body mass index and concentration of any organochlorine pesticide or PCB congeners 153, 138, 180, or ∑PCBs.
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