Use of thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS) on identification of odorant emission focus by volatile organic compounds characterisation

Volatile organic compounds (VOCs) from several different municipal solid wastes’ treatment plants in Mallorca (Spain) have been analysed by thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS). Ambient (immission) air was collected during February and March 2011 by active sampling onto sorbents Tenax™ TA and Carboxen™ 1000. The study presents the chemical characterisation of 93 volatile organic compounds (VOCs) from an overall set of 84 immission air samples. 70 VOCs were positively identified.The linear fit for all 93 external standard calibration, from 10 mg L⁻¹ to 150 mg L⁻¹ (n = 4), was within the range 0.974 < r² < 0.998. Limits of detection of the method (LOD) for all the standards were within the range 1.1–4,213 pg, as the absolute standard amount spiked into sorbent tubes in 1 μL standard mixture (dissolved in methanol).Overall results stated systematic correlation between waste’s nature and VOCs’ air composition. Organic wastes show main contribution of terpenes, waste water sludge residues’ of reduced sulphured compounds (RSCs) and municipal solid wastes show contribution of a wide sort of VOCs. The use of a chemometric approach for variable’s reduction to 12 principal components enables evaluation of similarities and dissimilarities between facilities. PCA clearly related samples to its corresponding facility on the basis of their VOCs composition and the ambient temperature.     

C2–C5 Hydrocarbon measurements in the Netherlands 1981–1991

Measurements of C₂–C₅ hydrocarbons on an hourly basis at the TNO site in Delft from 1982 to 1984 and at Moerdijk over the period 1981–1991 are presented. In combination with meteorological data (wind direction and wind speed) the Delft and Moerdijk series are evaluated to identify source categories, annual variations, background concentrations and trends. The C₂–C₅ hydrocarbon concentrations at Delft and Moerdijk are determined mainly by emission characteristics and meteorological dispersion; the dominant sources are relatively nearby and atmospheric degradation is not of much importance. Under conditions of high wind speed the concentrations measured at Moerdijk in the marine sector are close to the Atlantic background concentrations in winter and somewhat above this in summer. The continental background concentrations are higher than the marine background concentrations by a factor of almost two. The annual variation of acetylene is more pronounced than that of the other hydrocarbons, most likely due to a different seasonal variation in acetylene emissions. The annual variation of propene is smoother, indicating stronger sources in summer than in winter. This feature of propene is observed in continental as well as in marine sectors. The observations show that at Moerdijk C₂–C₄ concentrations measured in Rijnmond sector have decreased considerably since the early 1980s, corresponding with changes in emissions in that area. Averaged over all wind directions the trend of all species is downward, but for acetylene the trend is significant at a 95% confidence interval. The acetylene concentrations show an annual downward trend of 3% during the 1980s, supporting other estimates of decreasing hydrocarbon emissions from traffic over this period at the same rate.     

Analysis of particulate polycyclic aromatic hydrocarbons by on-line coupled supercritical fluid extraction–liquid chromatography–gas chromatography–mass spectrometry

An on-line supercritical fluid extraction–liquid chromatography–gas chromatography–mass spectrometry (SFE–LC–GC–MS) method was developed for the analysis of the particulate polycyclic aromatic hydrocarbons (PAHs). The limits of detection of the system for the quantification standards were in the range of 0.25–0.57 ng, while the limits of determinations for filter samples varied from 0.02 to 0.04 ng m⁻³ (24 h sampling). The linearity was excellent from 5 to 300 ng (R²>0.967). The analysis could be carried out in a closed system without tedious manual sample pretreatment and with no risk of errors by contamination or loss of the analytes. The results of the SFE–LC–GC–MS method were comparable with those for Soxhlet and shake-flask extractions with GC–MS. The new method was applied to the analysis of PAHs collected by high-volume filter in the Helsinki area to study the seasonal trend of the concentrations. The individual PAH concentrations varied from 0.015 to more than 1 ng m⁻³, while total PAH concentrations varied from 0.81 to 5.68 ng m⁻³. The concentrations were generally higher in winter than in summer. The mass percentage of the total PAHs in total suspended particulates ranged from 2.85×10⁻³% in July to 15.0×10⁻³% in December. Increased emissions in winter, meteorological conditions, and more serious artefacts during the sampling in summer season may explain the concentration profiles.     

Simulating chemistry–aerosol–cloud–radiation–climate feedbacks over the continental U.S. using the online-coupled Weather Research Forecasting Model with chemistry (WRF/Chem)

The chemistry–aerosol–cloud–radiation–climate feedbacks are simulated using WRF/Chem over the continental U.S. in January and July 2001. Aerosols can reduce incoming solar radiation by up to ?9% in January and ?16% in July and 2-m temperatures by up to 0.16 °C in January and 0.37 °C in July over most of the continental U.S. The NO₂ photolysis rates decrease in July by up to ?8% over the central and eastern U.S. where aerosol concentrations are high but increase by up to 7% over the western U.S. in July and up to 13% over the entire domain in January. Planetary boundary layer (PBL) height reduces by up to ?23% in January and ?24% in July. Temperatures and wind speeds in July in big cities such as Atlanta and New York City reduce at/near surface but increase at higher altitudes. The changes in PBL height, temperatures, and wind speed indicate a more stable atmospheric stability of the PBL and further exacerbate air pollution over areas where air pollution is already severe. Aerosols can increase cloud optical depths in big cities in July, and can lead to 500–5000 cm^?3 cloud condensation nuclei (CCN) at a supersaturation of 1% over most land areas and 10–500 cm^?3 CCN over ocean in both months with higher values over most areas in July than in January, particularly in the eastern U.S. The total column cloud droplet number concentrations are up to 4.9 × 10⁶ cm^?2 in January and up to 11.8 × 10⁶ cm^?2 in July, with higher values over regions with high CCN concentrations and sufficient cloud coverage. Aerosols can reduce daily precipitation by up to 1.1 mm day^?1 in January and 19.4 mm day^?1 in July thus the wet removal rates over most of the land areas due to the formation of small CCNs, but they can increase precipitation over regions with the formation of large/giant CCN. These results indicate potential importance of the aerosol feedbacks and an urgent need for their accurate representations in current atmospheric models to reduce uncertainties associated with climate change predictions.     

Characteristics of lead geochemistry and the mobility of Pb isotopes in the system of pedogenic rock–pedosphere–irrigated riverwater–cereal–atmosphere from the Yangtze River delta region,China

Knowledge of the characteristics of Pb and its isotopic transfer in different compartments is scant, especially for the mobility of Pb isotopes in the geochemical cycle. The present study characterizes differential Pb transport mechanism and the mobility of Pb isotopes in the pedogenic parent rock–pedosphere–irrigated riverwater–cereal–atmosphere system in the Yangtze River delta region, by determining Pb concentration and Pb isotopic ratios of pedogenic parent rocks, fluvial suspended particle matter, tillage soils, soil profiles, irrigated riverwater, fertilizer, Pb ore, cereal roots and grains. The results show that Pb isotopes in the geochemical cycle generally follow the equation of ²⁰⁸Pb/²⁰⁶Pb = −1.157 × ²⁰⁶Pb/²⁰⁷Pb + 3.46 (r² = 0.941). However, Pb isotopes have different mobility in different environmental matrixes. Whereas in the pedosphere, the heavier Pb (²⁰⁸Pb) usually shows stronger mobility relative to the lighter Pb, and is more likely to transfer into soil exchangeable Pb fraction and carbonates phase. The lighter Pb shows stronger transfer ability from soil to cereal grain via root compared to the heavier Pb. However, the cereal grains have lower ²⁰⁶Pb/²⁰⁷Pb and higher ²⁰⁸Pb/²⁰⁶Pb ratios than root and tillage soil, similar to the airborne Pb and anthropogenic Pb, implying that a considerable amount of Pb in cereal grains comes from the atmosphere. The estimate model shows that 16.7–52.6% (average: 33.5%) of Pb in rice grain is the airborne Pb.     

Dispersion of pollutants over land–water–land interface: Study using CALPUFF model

The CALMET/CALPUFF modeling system is used to study atmospheric dispersion of pollutant over land–water–land interface. It is shown that the default scheme used by CALMET/CALPUFF to handle inhomogeneous surfaces does not take care of the different turbulence characteristics over such surfaces. An alternative method is suggested to incorporate different turbulent characteristics over inhomogeneous surfaces by using the appropriate atmospheric stability category over different surfaces. The results show that the presence of water body can increase the ground level concentration by a factor of up to 50 for the width of water body varying from 1 km to 5 km. It is also shown that the effect of water body on the ground level concentration decreases as the distance from the water body increases. The present study showed that for land–water interface, the realistic specification of turbulence characteristics over inhomogeneous surfaces significantly changes the estimation of ground level concentration as compared to the default scheme available in the CALMET/CALPUFF modeling system and is expected to give realistic results.     

Effect of Fe–Mn–La-modified biochar composites on arsenic volatilization in flooded paddy soil

Environmental Science and Pollution Research - As can be volatilized naturally; however, this has adverse environmental effects. In this study, we investigated As volatilization in flooded paddy...     

Position-Controlled III–V Compound Semiconductor Nanowire Solar Cells by Selective-Area Metal–Organic Vapor Phase Epitaxy

We demonstrate position-controlled III–V semiconductor nanowires (NWs) by using selective-area metal–organic vapor phase epitaxy and their application to solar cells. Efficiency of 4.23% is achieved for InP core–shell NW solar cells. We form a ‘flexible NW array’ without a substrate, which has the advantage of saving natural resources over conventional thin film photovoltaic devices. Four junction NW solar cells with over 50% efficiency are proposed and discussed.     

A model for NOx–O3–terpene chemistry in chamber measurements of plant gas exchange

Cuvette measurements are a tool to analyse CO₂ exchange, transipiration and deposition/emission of different trace gases by plants. To verify these experimental methods and to use them efficiently we have developed a numerical model with atmospheric chemical reactions. The model includes reactions between 54 different chemical species in the gas phase. Using the model we are able to determine optimal size/flow rate ratios and cuvette cycles (closure times) from an experimental point of view. Using the cuvette model with atmospheric chemistry more accurate estimates for emissions/deposition rates of different species can be found. Some chemical reactions are significant, e.g. for NO and terpenes, as regards the analysis and interpretation of measured concentrations. With slower flow rates through a cuvette the significance of reactions is more pronounced. However, there are some species like ozone, where stomatal deposition is a dominant phenomenon and chemistry plays a minor role.     

Fungicidal Impact on Chickpea–Mesorhizobium Symbiosis

Abstract

The effects of carbendazim, captan, thiram, and mancozeb, on plant vitality, chlorophyll content, N uptake, protein content, nodulation, and seed yield in chickpea (Cicer arietinum) were assessed in a controlled environment. Seeds treated with fungicides at 1 and 1.5 g. a.i./kg seed had no significant adverse effect on plant vigor, seed yield, and N and protein contents. In contrast, fungicides applied at 2 g. a.i./kg of captan, thiram and mancozeb, significantly reduced the measured parameters. In general, the toxicity of fungicides in terms of seed yield increased in the following order: Control = carbendazim > thiram > captan > mancozeb. Total chlorophyll content in foliage declined consistently with fungicides dose rates and application days. Seeds treated with lower rates of fungicides significantly increased nodulation (nodule number per plant and its dry mass) and were compatible with chickpea inoculum used in this study. Although carbendazim at 2 g a.i./kg seed had no phytotoxic effect assessed under greenhouse conditions, it significantly reduced the chlorophyll content, nodulation (60 d) and N content in shoots.     

Another explanation of pollution–income patterns

The Andreoni and Levinson (2001) theoretical framework can be used to show that the shape of the environmental Kuznets curve can be explained without considering increasing returns to scale in pollution abatement technology, but simply by making explicit that the marginal disutility of pollution increases with income.     

Sources,distribution, and acidity of sulfate–ammonium aerosol in the Arctic in winter–spring

We use GEOS-Chem chemical transport model simulations of sulfate–ammonium aerosol data from the NASA ARCTAS and NOAA ARCPAC aircraft campaigns in the North American Arctic in April 2008, together with longer-term data from surface sites, to better understand aerosol sources in the Arctic in winter–spring and the implications for aerosol acidity. Arctic pollution is dominated by transport from mid-latitudes, and we test the relevant ammonia and sulfur dioxide emission inventories in the model by comparison with wet deposition flux data over the source continents. We find that a complicated mix of natural and anthropogenic sources with different vertical signatures is responsible for sulfate concentrations in the Arctic. East Asian pollution influence is weak in winter but becomes important in spring through transport in the free troposphere. European influence is important at all altitudes but never dominant. West Asia (non-Arctic Russia and Kazakhstan) is the largest contributor to Arctic sulfate in surface air in winter, reflecting a southward extension of the Arctic front over that region. Ammonium in Arctic spring mostly originates from anthropogenic sources in East Asia and Europe, with added contribution from boreal fires, resulting in a more neutralized aerosol in the free troposphere than at the surface. The ARCTAS and ARCPAC data indicate a median aerosol neutralization fraction [NH₄⁺]/(2[SO₄^2?] + [NO₃^?]) of 0.5 mol mol^?1 below 2 km and 0.7 mol mol^?1 above. We find that East Asian and European aerosol transported to the Arctic is mostly neutralized, whereas West Asian and North American aerosol is highly acidic. Growth of sulfur emissions in West Asia may be responsible for the observed increase in aerosol acidity at Barrow over the past decade. As global sulfur emissions decline over the next decades, increasing aerosol neutralization in the Arctic is expected, potentially accelerating Arctic warming through indirect radiative forcing and feedbacks.     

Occurrence of cyclophosphamide and epirubicin in wastewaters by direct injection analysis–liquid chromatography–high-resolution mass spectrometry

Background, aim, and scope

According to the high incidence of cancer worldwide, the amount of cytostatic drugs administered to patients has increased. These compounds are excreted to wastewaters, and therefore become potential water contaminants. At this stage, very little is known on the presence and elimination of cytostatic compounds in wastewater treatment plants (WWTP). The aim of this study was to develop a liquid chromatography?Chigh-resolution mass spectrometry (LC?COrbitrap?CMS) method for the determination of cyclophosphamide and epirubicin in wastewaters. These compounds represent two outmost used cytostatic agents.

Materials and methods

Extraction and analytical conditions were optimized for cyclophosphamide and epirubicin in wastewater. Both solid-phase extraction using Oasis 200?mg hydrophilic?Clipophilic balanced (HLB) cartridges and direct injection analysis were evaluated. Mass spectral characterization and fragmentation conditions were optimized at 50,000 resolving power (full width at half maximum, m/z 200) to obtain maximum sensitivity and identification performance. Quality parameters (recoveries, limits of detection, and repetitivity) of the methods developed were determined, and best performance was obtained with direct water analysis of the centrifuged wastewater. Finally, this method was applied to determine the presence of cyclophosphamide and epirubicin in wastewaters from a hospital effluent, an urban effluent, and influents and effluents from three WWTP.

Results and discussion

Cyclophosphamide and epirubicin were recovered after 50?mL preconcentration on solid-phase extraction 200?mg Oasis HLB cartridges (87% and 37%, respectively), and no breakthrough was observed by extracting 500?mL of water. Limits of detection were of 0.35 and 2.77?ng/L for cyclophosphamide and epirubicin, respectively. On the other hand, direct injection of water spiked at 1???g/L provided recoveries of 107% for cyclophosphamide and 44% for epirubicin and limits of detection from 3.1 to 85?ng?L^?1, respectively. The analysis of wastewaters using direct injection analysis revealed the presence of cyclophosphamide and epirubicin in WWTP influents and hospital and urban effluents at levels ranging from 5.73 to 24.8???g?L^?1.

Conclusions

The results obtained in this study demonstrate the capability of LC?COrbitrap?CMS for accurate trace analysis of these very polar contaminants. This method permitted to identify cyclophosphamide and epirubicin in wastewaters and influents of WWTP, but no traces were detected in WWTP effluents. The methodology herein developed is sensitive and robust and applicable for screening of a large number of samples since no preconcentration is needed.     

Urban–rural differences in atmospheric mercury speciation

Measurements of gaseous elemental mercury (GEM), particulate mercury (Hg_p), and reactive gaseous mercury (RGM) were concurrently recorded at an urban site in Detroit and a rural site in Dexter, both in Michigan for the calendar year 2004. Their average concentrations (±standard deviation) for the urban area were 2.5 ± 1.4 ng m^?3, 18.1 ± 61.0 pg m^?3, and 15.5 ± 54.9 pg m^?3, respectively, while their rural counterparts were 1.6 ± 0.6 ng m^?3, 6.1 ± 5.5 pg m^?3, and 3.8 ± 6.6 pg m^?3, respectively. The medians of urban-to-rural ratios of Hg concentrations indicate approximately 1-fold, 2-fold, and 3-fold gradients between Detroit and Dexter for GEM, Hg_p, and RGM, respectively. The urban–rural differences in Hg also varied considerably on different temporal scales and with wind flow patterns, which was most evident in RGM. Our results show that while Hg at both sites was impacted by regional sources, meteorological conditions, and photochemical transformations, the extent of variations in the observed urban-to-rural gradients, particularly in RGM, cannot be fully accounted for by these processes. Both analyses of the annual data and case studies indicate that the more variable and episodic nature of Hg, particularly RGM, seen in Detroit compared with Dexter, was the result of direct impact from local anthropogenic sources.     

Atmospheric composition change: Climate–Chemistry interactions

Chemically active climate compounds are either primary compounds like methane (CH₄), removed by oxidation in the atmosphere, or secondary compounds like ozone (O₃), sulfate and organic aerosols, both formed and removed in the atmosphere. Man-induced climate–chemistry interaction is a two-way process: Emissions of pollutants change the atmospheric composition contributing to climate change through the aforementioned climate components, and climate change, through changes in temperature, dynamics, the hydrological cycle, atmospheric stability, and biosphere-atmosphere interactions, affects the atmospheric composition and oxidation processes in the troposphere. Here we present progress in our understanding of processes of importance for climate–chemistry interactions, and their contributions to changes in atmospheric composition and climate forcing. A key factor is the oxidation potential involving compounds like O₃ and the hydroxyl radical (OH). Reported studies represent both current and future changes. Reported results include new estimates of radiative forcing based on extensive model studies of chemically active climate compounds like O₃, and of particles inducing both direct and indirect effects. Through EU projects like ACCENT, QUANTIFY, and the AeroCom project, extensive studies on regional and sector-wise differences in the impact on atmospheric distribution are performed. Studies have shown that land-based emissions have a different effect on climate than ship and aircraft emissions, and different measures are needed to reduce the climate impact. Several areas where climate change can affect the tropospheric oxidation process and the chemical composition are identified. This can take place through enhanced stratospheric–tropospheric exchange of ozone, more frequent periods with stable conditions favoring pollution build up over industrial areas, enhanced temperature induced biogenic emissions, methane releases from permafrost thawing, and enhanced concentration through reduced biospheric uptake. During the last 5–10 years, new observational data have been made available and used for model validation and the study of atmospheric processes. Although there are significant uncertainties in the modeling of composition changes, access to new observational data has improved modeling capability. Emission scenarios for the coming decades have a large uncertainty range, in particular with respect to regional trends, leading to a significant uncertainty range in estimated regional composition changes and climate impact.     

APCA Financial Statements for FY 1981–82

ABSTRACT

The objective of this study was to determine whether ultraviolet-light-emitting diodes (UV-LEDs) could serve as an efficient photon source for heterogeneous photocatalytic oxidation (PCO). An LED module consisting of 12 high-power UV-A (λ_max?=?365 nm) LEDs was designed to be interchangeable with a UV-A fluorescent black light blue (BLB) lamp for a bench scale annular reactor packed with silica-titania composite (STC) pellets. Lighting and thermal properties of the module were characterized to assess its uniformity and total irradiance. A forward current (I _F) of 100 mA delivered an average irradiance of 4.0 mW cm^?2 at a distance of 8 mm, which is equivalent to the maximum output of the BLB, but the irradiance of the LED module was less uniform than that of the BLB. The LED and BLB reactors were tested for the oxidization of ethanol (50 ppm_v) in a continuous-flow-through mode with 0.94 sec residence time. At the same average irradiance, the UV-A LED reactor resulted in a lower CO₂ production rate (19.8 vs. 28.6 nmol L^?1 s^?1), lower ethanol removal (80% vs. 91%), and lower mineralization efficiency (28% vs. 44%) than the UV-A BLB reactor. Ethanol mineralization was enhanced with the increase of the irradiance at the catalyst surface. This result suggests that reduced ethanol mineralization in the LED reactor relative to the BLB reactor at the same average irradiance could be attributed to the nonuniform irradiance over the photocatalyst, that is, a portion of the catalyst was exposed to less than the average irradiance. The potential of UV-A LEDs may be fully realized by optimizing the light distribution over the catalyst and utilizing their instantaneous “on” and “off” feature for periodic irradiation. Nevertheless, our results also showed that the current UV-A LED module had the same wall plug efficiency (WPE) of 13% as that of the UV-A BLB, demonstrating that UV-A LEDs are a viable photon source both in terms of WPE and PCO efficiency.

IMPLICATIONS Mercury (Hg)-vapor lamps are common UV sources for photocatalysis but create safety and environmental concerns because they contain Hg; furthermore, they have a relatively short life span. This paper demonstrated that the UV-A LED is a viable alternative to the Hg-vapor lamps without sacrificing PCO efficiency if the design of the LED arrays is improved to increase the lighting uniformity. The use of LEDs could eliminate hazardous Hg wastes and extend the application of photocatalysis in places requiring more compact and robust air purification solutions.