Nighttime air quality under desert conditions

Nighttime concentrations of the gas phase nitrate radical (NO3) were successfully measured during a four week field campaign in an arid urban location, Reno Nevada, using long-path Differential Optical Absorbance Spectrometry (DOAS). While typical concentrations of NO3 ranged from 5 to 20ppt, elevated concentrations were observed during a wildfire event. Horizontal mixing in the free troposphere was considerable because the sampling site was above the stable nocturnal boundary layer every night and this justified a box modeling approach. Process analysis of box model simulations showed NO3 accounted for approximately half of the loss of internal olefins, 60% of the isoprene loss, and 85% of the α-pinene loss during the nighttime hours during a typical night of the field study. The NO3+aldehyde reactions were not as important as anticipated. On a polluted night impacted by wildfires upwind of the sampling location, NO3 reactions were more important. Model simulations overpredicted NO2 concentrations for both case studies and inorganic chemistry was the biggest influence on NO3 concentrations and on nitric acid formation. The overprediction may be due to additional NO2 loss processes that were not included in the box model, as deposition and N2O5 uptake had no significant effect on NO2 levels

The impact of bark beetle infestations on monoterpene emissions and secondary organic aerosol formation in western North America

Over the last decade, extensive beetle outbreaks in western North America have destroyed over 100 000 km2 of forest throughout British Columbia and the western United States. Beetle infestations impact monoterpene emissions through both decreased emissions as trees are killed (mortality effect) and increased emissions in trees under attack (attack effect). We use 14 yr of beetle-induced tree mortality data together with beetle-induced monoterpene emission data in the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM) to investigate the impact of beetle-induced tree mortality and attack on monoterpene emissions and secondary organic aerosol (SOA) formation in western North America. Regionally, beetle infestations may have a significant impact on monoterpene emissions and SOA concentrations, with up to a 4-fold increase in monoterpene emissions and up to a 40% increase in SOA concentrations in some years (in a scenario where the attack effect is based on observed lodgepole pine response). Responses to beetle attack depend on the extent of previous mortality and the number of trees under attack in a given year, which can vary greatly over space and time. Simulated enhancements peak in 2004 (British Columbia) and 2008 (US). Responses to beetle attack are shown to be substantially larger (up to a 3-fold localized increase in summertime SOA concentrations) in a scenario based on bark-beetle attack in spruce trees. Placed in the context of observations from the IMPROVE network, the changes in SOA concentrations due to beetle attack are in most cases small compared to the large annual and interannual variability in total organic aerosol which is driven by wildfire activity in western North America. This indicates that most beetle-induced SOA changes are not likely detectable in current observation networks; however, these changes may impede efforts to achieve natural visibility conditions in the national parks and wilderness areas of the western United States.National Science Foundation (U.S.) (ATM- 0929282)National Science Foundation (U.S.) (ATM-0939021)National Science Foundation (U.S.) (ATM-0938940)United States. Dept. of Energy. Office of Scienc

Scoping studies to establish the capability and utility of a real-time bioaerosol sensor to characterise emissions from environmental sources

A novel dual excitation wavelength based bioaerosol sensor with multiple fluorescence bands called Spectral Intensity Bioaerosol Sensor (SIBS) has been assessed across five contrasting outdoor environments. The mean concentrations of total and fluorescent particles across the sites were highly variable being the highest at the agricultural farm (2.6 cm−3 and 0.48 cm−3, respectively) and the composting site (2.32 cm−3 and 0.46 cm−3, respectively) and the lowest at the dairy farm (1.03 cm−3 and 0.24 cm−3, respectively) and the sewage treatment works (1.03 cm−3 and 0.25 cm−3, respectively). In contrast, the number-weighted fluorescent fraction was lowest at the agricultural site (0.18) in comparison to the other sites indicating high variability in nature and magnitude of emissions from environmental sources. The fluorescence emissions data demonstrated that the spectra at different sites were multimodal with intensity differences largely at wavelengths located in secondary emission peaks for λex 280 and λex 370. This finding suggests differences in the molecular composition of emissions at these sites which can help to identify distinct fluorescence signature of different environmental sources. Overall this study demonstrated that SIBS provides additional spectral information compared to existing instruments and capability to resolve spectrally integrated signals from relevant biological fluorophores could improve selectivity and thus enhance discrimination and classification strategies for real-time characterisation of bioaerosols from environmental sources. However, detailed lab-based measurements in conjunction with real-world studies and improved numerical methods are required to optimise and validate these highly resolved spectral signatures with respect to the diverse atmospherically relevant biological fluorophores

Atmospheric Radiation Measurements Aerosol Intensive Operating Period: Comparison of aerosol scattering during coordinated flights

Journal of Geophyshysical Research, Vol. 111, No. D5, D05S09The article of record as published may be located at http://dx.doi.org/10.1029/2005JD006250In May 2003, a Twin Otter airplane, equipped with instruments for making in situ measurements of aerosol optical properties, was deployed during the Atmospheric Radiation Measurements (ARM) Program’s Aerosol Intensive Operational Period in Oklahoma. Several of the Twin Otter flights were flown in formation with an instrumented light aircraft (Cessna 172XP) that makes routine in situ aerosol profile flights over the site. This paper presents comparisons of measured scattering coefficients at 467 nm, 530 nm, and 675 nm between identical commercial nephelometers aboard each aircraft. Overall, the agreement between the two nephelometers decreases with longer wavelength. During the majority of the flights, the Twin Otter flew with a diffuser inlet while the Cessna had a 1 mm impactor, allowing for an estimation of the fine mode fraction aloft. The fine mode fraction aloft was then compared to the results of a ground-based nephelometer. Comparisons are also provided in which both nephelometers operated with identical 1 mm impactors. These scattering coefficient comparisons are favorable at the longer wavelengths (i.e., 530 nm and 675 nm), yet differed by approximately 30% at 467 nm. Mie scattering calculations were performed using size distribution measurements, made during the level flight legs. Results are also presented from Cadenza, a new continuous wave cavity ring-down (CW-CRD) instrument, which compared favorably (i.e., agreed within 2%) with data from other instruments aboard the Twin Otter. With this paper, we highlight the significant implications of coarse mode (larger than 1 mm) aerosol aloft with respect to aerosol optical properties

Effects of Inquiry-based Learning on Students’ Science Literacy Skills and Confidence

Calls for reform in university education have prompted a movement from teacher- to student-centered course design, and included developments such as peer-teaching, problem and inquiry-based learning. In the sciences, inquiry-based learning has been widely promoted to increase literacy and skill development, but there has been little comparison to more traditional curricula. In this study, we demonstrated greater improvements in students’ science literacy and research skills using inquiry lab instruction. We also found that inquiry students gained self-confidence in scientific abilities, but traditional students’ gain was greater –likely indicating that the traditional curriculum promoted over-confidence. Inquiry lab students valued more authentic science exposure but acknowledged that experiencing the complexity and frustrations faced by practicing scientists was challenging, and may explain the widespread reported student resistance to inquiry curricula

Atmospheric organic matter in clouds: exact masses and molecular formula identification using ultrahigh-resolution FT-ICR mass spectrometry

Clouds alter the composition of atmospheric aerosol by acting as a medium for interactions between gas- and particulate-phase substances. To determine the cloud water atmospheric organic matter (AOM) composition and study the cloud processing of aerosols, two samples of supercooled clouds were collected at the Storm Peak Laboratory near Steamboat Springs, Colorado (3220 m a.s.l.). Approximately 3000 molecular formulas were assigned to ultrahigh-resolution mass spectra of the samples after using a reversed-phase extraction procedure to isolate the AOM components from the cloud water. Nitrogen-containing compounds (CHNO compounds), sulfur-containing compounds (CHOS and CHNOS compounds) and other oxygen-containing compounds (CHO compounds) with molecular weights up to 700 Da were observed. Average oxygen-to-carbon ratios of ∼0.6 indicate a slightly more oxidized composition than most water-soluble organic carbon identified in aerosol studies, which may result from aqueous oxidation in the clouds. The AOM composition indicates significant influences from biogenic secondary organic aerosol (SOA) and residential wood combustion. We observed 60% of the cloud water CHO molecular formulas to be identical to SOA samples of α-pinene, β-pinene, d-limonene, and β-caryophyllene ozonolysis. CHNO compounds had the highest number frequency and relative abundances and are associated with residential wood combustion and NOxoxidation. Multiple nitrogen atoms in the assigned molecular formulas for the nighttime cloud sample composite were observed, indicating the significance of nitrate radical reactions on the AOM composition. Several CHOS and CHNOS compounds with reduced sulfur (in addition to the commonly observed oxidized sulfur-containing compounds) were also observed; however further investigation is needed to determine the origin of the reduced sulfur-containing compounds. Overall, the molecular composition determined using ultrahigh-resolution Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry provides an unambiguous identification of the cloud water organic anion composition in the Rocky Mountain area that could help to improve the understanding of aqueous-phase processes

Máquina de Aspectos: un enfoque alternativo para la implementación de aspectos.

La Programación Orientada a Aspectos (POA) es un nuevo paradigma de programación que propone mecanismos para soportar la separación de los aspectos no funcionales de los sistemas software. Una herramienta POA consiste en tres componentes principales: un lenguaje de programación base, un lenguaje de programación orientado a aspectos y un tejedor de aspectos (weaver). El presente trabajo propone un enfoque alternativo para la implementación de aspectos basado en la especificación de los mismos y sus elementos.Eje: Ingeniería de software y base de datosRed de Universidades con Carreras en Informática (RedUNCI

Máquina de Aspectos: un enfoque alternativo para la implementación de aspectos.

La Programación Orientada a Aspectos (POA) es un nuevo paradigma de programación que propone mecanismos para soportar la separación de los aspectos no funcionales de los sistemas software. Una herramienta POA consiste en tres componentes principales: un lenguaje de programación base, un lenguaje de programación orientado a aspectos y un tejedor de aspectos (weaver). El presente trabajo propone un enfoque alternativo para la implementación de aspectos basado en la especificación de los mismos y sus elementos.Eje: Ingeniería de software y base de datosRed de Universidades con Carreras en Informática (RedUNCI

Population Monitoring of Diamondback Moth (Plutella Xylostella) and Evaluating Its Attacking Impact on Growth & Yield of Cauliflower at District Tando Allahyar

This study was intended to evaluate the population monitoring of diamondback moth and its attacking impact on growth and yield of cauliflower, at District Tando Allahyar. The experimental site is located at 25.27570 N and 68.421500 E. Two local varieties (sathri and nawri) of cauliflower were cultivated. The population of DBM was monitored for the entire crop period using direct count and light trap methods. Twenty five plants were randomly selected for direct count observations and a light trap was installed at the field. The impact of DBM attack on growth, leaf quality and yield of cauliflower was analyzed by selecting and labelling 25 plants at the time of sowing. The results indicate that, the mean values of DBM population under direct count method was ranging from 0.24 to 2.15. The maximum (2.15) and minimum (0.24) mean values were observed on 4th and 12th (last) week, respectively. Under light trap method, the maximum and minimum DBM population was observed on the 6th and 12th week, respectively. The population trend indicates a rapid increase to gradually decrease in the number of moths. Statistically, a significant difference was observed in DBM population throughout the observations. With regard to the growth and yield of cauliflower, the results indicate that, the height of leaf was reduced by 12.38, 23.19, 35.69, 41.45 and 45.72 %, weight of leaf was reduced by 12.55, 21.24, 28.98, 40.33 and 48.93 % and the average yield of flower was reduced by 9.26 %, 17.78 %, 27.41 %, 36.11 % and 46.48 %, under the DBM attack of 2, 4, 6, 8, and 10 moths, respectively. Under leaf quality assessment, the leaf was observed with one or several colors from light green, pale, light yellow, dark yellow, brown and red. From the outcomes of this study, it is recommended that, the DBM at larvae stage highly damaged the cauliflower growth rate and reduces the crop yield. Therefore, the regular scouting of pest should be carried out and the recommended application rate of pesticides should be applied for effective management of diamondback moth particularly in cauliflower. &nbsp