A comparative study on emergent pollutants photo-assisted degradation using ruthenium modified titanate nanotubes and nanowires as catalysts

Several methods have been used to tailor nanomaterials structure and properties.Sometimes,slight changes in the structure outcomes expressive improvements in the optical and photocatalytic properties of semiconductor nanoparticles.In this context,the influence of the metal doping and the morphology on a catalyst performance was studied in this work.Here,ruthenium doped titanate nanotubes(RuTNT) were synthesised for the first time using an amorphous Ru-containing precursor.Afterwards,the photocatalytic performance of this sample was compared to the one obtained for ruthenium titanate nanowires(RuTNW),recently reported.Two samples,RuTNW and RuTNT,were produced using the same Ru-containing precursor but distinct hydrothermal methodologies.The powders were structural,morphological and optical characterized by X-ray diffraction and fluorescence,transmission electron microscopy,Raman,X-ray photoelectron and photoluminescence spectroscopies.Distinct variations on the structural and optical properties of the RuTNT and RuTNW nanoparticles,due to ruthenium incorporation were observed.Their potential use as photocatalysts was evaluated on the hydroxyl radical photo-assisted production.Both samples were catalytic for this reaction,presenting better performances than the pristine counterparts,being RuTNT the best photocatalyst.Subsequently,the degradation of two emergent pollutants,caffeine and sulfamethazine,was studied.RuTNT demonstrated to be better photocatalyst than RuTNW for caffeine but identical performances were obtained for sulfamethazine.For both catalysts,the degradation mechanism of the pollutants was explored through the identification and quantification of the intermediate compounds produced and several differences were found.This indicates the importance of the structural and morphological aspects of a material on its catalytic performance.     

微量元素的原位显微分析

<正> 我们将微量元素的原位显微分析定义为“光片中单个矿物相的微量元素浓度(<1000ppm)的测量”,这类似于电子探针对主量元素的分析。我们认为,这样的测量是重要的,它能对岩石学和地球化学提供一种新的尺度。本文既是对原先所作工作的回顾,     

Genetic and genotoxic aspects on methyl mercury

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Methane and nitrous oxide emissions from a subtropical coastal embayment (Moreton Bay, Australia)

Surface water methane (CH₄) and nitrous oxide (N₂O) concentrations and fluxes were investigated in two subtropical coastal embayments (Bramble Bay and Deception Bay, which are part of the greater Moreton Bay, Australia). Measurements were done at 23 stations in seven campaigns covering different seasons during 2010-2012. Water-air fluxes were estimated using the Thin Boundary Layer approach with a combination of wind and currents-based models for the estimation of the gas transfer velocities. The two bays were strong sources of both CH₄ and N₂O with no significant differences in the degree of saturation of both gases between them during all measurement campaigns. Both CH₄ and N₂O concentrations had strong temporal but minimal spatial variability in both bays. During the seven seasons, CH₄ varied between 500% and 4000% saturation while N₂O varied between 128 and 255% in the two bays. Average seasonal CH₄ fluxes for the two bays varied between 0.5 ± 0.2 and 6.0 ± 1.5 mg CH₄/(m²·day) while N₂O varied between 0.4 ± 0.1 and 1.6 ± 0.6 mg N₂O/(m²·day). Weighted emissions (t CO₂-e) were 63%-90% N₂O dominated implying that a reduction in N₂O inputs and/or nitrogen availability in the bays may significantly reduce the bays' greenhouse gas (GHG) budget. Emissions data for tropical and subtropical systems is still scarce. This work found subtropical bays to be significant aquatic sources of both CH₄ and N₂O and puts the estimated fluxes into the global context with measurements done from other climatic regions.     

Fuelwood assessment at the micro-watershed level:a case study in Garhwal Himalaya,India

Biomass,as fuelwood,is one of the major sources of energy in rural areas,especially in the mountainous regions of the world.As the increasing human population exerts more pressure on the forest thereby inducing an adverse effect on the sustainability of the ecosystem,which consequently causes fuelwood crisis at a local level,this crisis is spatio-temporal in nature.Thus,the major objective of this study is to assess the sustainability of fuelwood at different probable scenarios at a micro watershed level.The present study was conducted in the Phakot watershed,the Tehri Garhwal district of central Himalaya in India,during 2006-2008.Based on the vegetation composition in the study area,the net primary productivity(NPP)value of the Oak forest,and mixed oak and sal forests,was used for the quantification of fuelwood availability in evergreen and deciduous forests,respectively.The fuelwood demand was calculated on the basis of seasonal fuelwood consumption values.Nine probable permutations for availability-demand scenarios assuming the existence of high(H),low(L)and average(A)conditions were analyzed for evaluating the stress.The available annual harvestable fuelwood in the watershed is in the minimum and maximum ranges of 2283.28 to 4066.00 tons,respectively,per year whereas it has a demand of 110.76 tons as the minimum to 3659 tons as the maximum annually.This shows that in the current availabilitydemand scenario,the watershed does not have fuelwood crisis in the present situation but needs to maintain the sustainability of the system.Based on our study,it is concluded that,globally,more spatio-temporal study is required to understand the issues at the local level.     

Graduated driver licensing: the New Zealand experience

In New Zealand, on 1 August 1987, a three-stage graduated driver licensing (GDL) system that applied to all new drivers aged 15-24 years was introduced. The essential elements of GDL were a 6-month learner license (supervised driving) and an 18-month restricted license stage (with restrictions on night driving and carrying passengers). A blood alcohol limit of 0.03 mg% applied at both stages. EVALUATION STUDIES: Early studies indicated that young people were reasonably accepting of the restrictions, with the passenger restriction being the least acceptable. Problems of compliance with the restricted license driving restrictions were reported. Evaluations of the impact of the graduated driver licensing (GDL) on serious traffic-related injury showed that up until 1991-1992, an 8% reduction could be attributed to GDL. At this time, it was considered that reduced exposure was the main reason for this reduction. However, the number of fatalities and hospital admissions among young people continued to decline, as did the population rate and the rate per number of licensed drivers among the young driver age group. A further evaluation study showed that drivers with a restricted license had a smaller proportion of crashes at night, and with passengers, compared with drivers licensed before GDL. IMPACT OF GDL: These results suggested that GDL restrictions had contributed to the reduction in crashes among young people and that it was not simply a case of reduced exposure to risk. An update of the most recent crash statistics indicated that, compared with older age groups, the fatal and serious injury crash rate among young people has remained substantially below the pre-GDL level. This suggests that the impact of GDL has not diminished over time.     

In situ soil water extraction: a review

The knowledge of the composition and fluxes of vadose zone water is essential for a wide range of scientific and practical fields, including water-use management, pesticide registration, fate of xenobiotics, monitoring of disposal from mining and industries, nutrient management of agricultural and forest ecosystems, ecology, and environmental protection. Nowadays, water and solute flow can be monitored using either in situ methods or minimally invasive geophysical measurements. In situ information, however, is necessary to interpret most geophysical data sets and to determine the chemical composition of seepage water. Therefore, we present a comprehensive review of in situ soil water extraction methods to monitor solute concentration, solute transport, and to calculate mass balances in natural soils. We distinguished six different sampling devices: porous cups, porous plates, capillary wicks, pan lysimeters, resin boxes, and lysimeters. For each of the six sampling devices we discuss the basic principles, the advantages and disadvantages, and limits of data acquisition. We also give decision guidance for the selection of the appropriate sampling system. The choice of material is addressed in terms of potential contamination, filtering, and sorption of the target substances. The information provided in this review will support scientists and professionals in optimizing their experimental set-up for meeting their specific goals.     

Greenhouse gas emissions during co-composting of calf mortalities with manure

Composting may be a viable on-farm option for disposal of cattle carcasses. This study investigated greenhouse gas emissions during co-composting of calf mortalities with manure. Windrows were constructed that contained manure + straw (control compost [CK]) or manure + straw + calf mortalities (CM) using two technologies: a tractor-mounted front-end loader or a shredder bucket. Composting lasted 289 d. The windrows were turned twice (on Days 72 and 190), using the same technology used in their creation. Turning technology had no effect on greenhouse gas emissions or the properties of the final compost. The CO2 (75.2 g d(-1) m(-2)), CH4 (2.503 g d(-1) m(-2)), and N2O (0.370 g d(-1) m(-2)) emissions were higher (p < 0.05) in CM than in CK (25.7, 0.094, and 0.076 g d(-1) m(-2) for CO2, CH4, and N2O, respectively), which reflected differences in materials used to construct the compost windrows and therefore their total C and total N contents. The final CM compost had higher (p < 0.05) total N, total C, and mineral N content (NO3*+ NO2* + NH4+) than did CK compost and therefore has greater agronomic value as a fertilizer.     

An empirical model of soil chemical properties that regulate methane production in Japanese rice paddy soils

To understand which soil chemical properties are the best predictors of CH4 production in rice paddy soils, a model was developed with empirical data from nine types of rice soils collected around Japan and anaerobically incubated at 30 degrees C for 16 wk in laboratory conditions. After 1, 2, 4, 8, and 16 wk of incubation, CO2, CH4, and Fe(II) were measured to understand soil organic matter decomposition and iron (Fe) reduction. Available N (N ava) was also measured at the end of incubation. The results showed that decomposable C and reducible Fe are two key parameters that regulate soil CH(4) production (P CH4). There was a significant relationship between decomposable C and available N (N ava) (r2 = 0.975**). Except for a sandy soil sample, a significant relationship between total Fe (Fe total) and reducible Fe was found. From this experiment, a simple model of soil CH4 production was developed: P CH4 = 1.593N(ava) - 2.460Fe total/1000 (each unit was mg kg(-1) soil). After simulated CH4 production by two soil chemical properties as above, there was a significant consistency between model simulation and actual measurement (r2 = 0.831**).     

Lability of drinking water treatment residuals (WTR) immobilized phosphorus: aging and pH effects

Time constraints associated with conducting long-term (>20 yr) field experiments to test the stability of drinking water treatment residuals (WTR) sorbed phosphorus (P) inhibit improved understanding of the fate of sorbed P in soils when important soil properties (e.g., pH) change. We used artificially aged samples to evaluate aging and pH effects on lability of WTR-immobilized P. Artificial aging was achieved through incubation at elevated temperatures (46 or 70 degrees C) for 4.5 yr, and through repeated wetting and drying for 2 yr. Using a modified isotopic ((32)P) dilution technique, coupled with a stepwise acidification procedure, we monitored changes in labile P concentrations over time. This technique enabled evaluation of the effect of pH on the lability of WTR-immobilized P. Within the pH range of 4 to 7, WTR amendment, coupled with artificial aging, ultimately reduced labile P concentrations by > or = 75% relative to the control (no-WTR) samples. Soil samples with different physicochemical properties from two 7.5-yr-old, one-time WTR-amended field sites were utilized to validate the trends observed with the artificially aged samples. Despite the differences in physicochemical properties among the three (two field-aged and one artificially aged) soil samples, similar trends of aging and pH effects on lability of WTR-immobilized P were observed. Labile P concentrations of the WTR-amended field-aged samples of the two sites decreased 6 mo after WTR amendment and the reduction persisted for 7.5 yr, ultimately resulting in > or = 70% reduction, compared to the control plots. We conclude that WTR application is capable of reducing labile P concentration in P-impacted soils, doing so for a long time, and that within the commonly encountered range of pH values for agricultural soils WTR-immobilized P should be stable.