Evidence for an unidentified non-photochemical ground-level source of formaldehyde in the Po Valley with potential implications for ozone production
Kaiser, J. ; Wolfe, G.M. ; Bohn, B. ; Ganzeveld, L.N. - \ 2015
Atmospheric Chemistry and Physics 15 (2015). - ISSN 1680-7316 - p. 1289 - 1298.
volatile organic-compounds - exchange cafe model - total oh reactivity - tropospheric degradation - chemical mechanism - gas-phase - part - atmosphere - forest - hydrocarbons
Ozone concentrations in the Po Valley of northern Italy often exceed international regulations. As both a source of radicals and an intermediate in the oxidation of most volatile organic compounds (VOCs), formaldehyde (HCHO) is a useful tracer for the oxidative processing of hydrocarbons that leads to ozone production. We investigate the sources of HCHO in the Po Valley using vertical profile measurements acquired from the airship Zeppelin NT over an agricultural region during the PEGASOS 2012 campaign. Using a 1-D model, the total VOC oxidation rate is examined and discussed in the context of formaldehyde and ozone production in the early morning. While model and measurement discrepancies in OH reactivity are small (on average 3.4 ± 13%), HCHO concentrations are underestimated by as much as 1.5 ppb (45%) in the convective mixed layer. A similar underestimate in HCHO was seen in the 2002–2003 FORMAT Po Valley measurements, though the additional source of HCHO was not identified. Oxidation of unmeasured VOC precursors cannot explain the missing HCHO source, as measured OH reactivity is explained by measured VOCs and their calculated oxidation products. We conclude that local direct emissions from agricultural land are the most likely source of missing HCHO. Model calculations demonstrate that radicals from degradation of this non-photochemical HCHO source increase model ozone production rates by as much as 0.6 ppb h-1 (12%) before noon.
Effect of ecosystem services provided by urban greenb infrastructure on indoor environment: a literature review
Wang, Y. ; Bakker, F. ; Groot, R.S. de; Woertche, H. - \ 2014
Building and Environment 77 (2014). - ISSN 0360-1323 - p. 88 - 100.
volatile organic-compounds - air-quality - contingent valuation - carbon sequestration - thermal performance - heat-island - residential buildings - outdoor relationships - particulate matter - biogenic emissions
The influence of urban green infrastructure on the indoor environment and the effects on human comfort and economic consequences are still unclear. This paper gives a systematic overview of the relationship, in terms of so-called ‘ecosystem services’, between urban green infrastructure and the indoor environment through a literature review in different disciplines. Urban green infrastructure (mainly trees, green walls and roofs) was found to contribute, both positively and negatively, to the indoor environment via the influence on the climate, energy use, air quality, sonic environment and aesthetic quality. Four main factors that influence these effects were identified, being vegetation characteristics, building characteristics (including layout and geometry), and geographical conditions. Although the reviewed papers have investigated the different ecosystem services on a wide range of space and time scales, the performance of urban green on the meso- and macro climate has received less attention than on the micro scale. Also direct effects of urban green infrastructure on indoor air quality and sonic environment were rarely studied. Another finding is that, whereas the modelling approach on climate regulation has been widely adopted by researchers throughout the world, empirical studies have mainly been performed in the USA. We also analysed the data found on economic implications. The economic effects of adjoining vegetation and green roofs on climate regulation provided energy savings of up to almost $250/tree/year, while the air quality regulation was valued between $0.12 and $0.6/m2 tree cover/year. Maximum monetary values attributed to noise regulation and aesthetic appreciation of urban green were $20 – $25/person/year, respectively. Of course these values are extremely time- and context-dependent but do give an indication of the potential economic effects of investing in urban green infrastructure. Based on this review, we conclude that new methods, measurement instruments and field experiments are needed to improve empirically supported correlations and develop concrete recommendations for urban planning and design.
Metabolomics in melon: A new opportunity for aroma analysis
Allwood, J.W. ; Cheung, W.W.L. ; Xu, Y. ; Mumm, R. ; Vos, C.H. de; Deborde, C. ; Biais, B. ; Maucourt, M. ; Berger, Y. ; Schaffer, A. ; Rolin, D. ; Moing, A. ; Hall, R.D. ; Goodacre, R. - \ 2014
Phytochemistry 99 (2014). - ISSN 0031-9422 - p. 61 - 72.
charentais cantaloupe melons - volatile organic-compounds - oxidase antisense gene - cucumis-melo - gas-chromatography - flavor compounds - cv makdimon - fruit - constituents - sulfur
Cucumis melo fruit is highly valued for its sweet and refreshing flesh, however the flavour and value are also highly influenced by aroma as dictated by volatile organic compounds (VOCs). A simple and robust method of sampling VOCs on polydimethylsiloxane (PDMS) has been developed. Contrasting cultivars of C. melo subspecies melo were investigated at commercial maturity: three cultivars of var. Cantalupensis group Charentais (cv. Cézanne, Escrito, and Dalton) known to exhibit differences in ripening behaviour and shelf-life, as well as one cultivar of var. Cantalupensis group Ha’Ogan (cv. Noy Yisre’el) and one non-climacteric cultivar of var. Inodorus (cv. Tam Dew). The melon cultivar selection was based upon fruits exhibiting clear differences (cv. Noy Yisre’el and Tam Dew) and similarities (cv. Cézanne, Escrito, and Dalton) in flavour. In total, 58 VOCs were detected by thermal desorption (TD)-GC–MS which permitted the discrimination of each cultivar via Principal component analysis (PCA). PCA indicated a reduction in VOCs in the non-climacteric cv. Tam Dew compared to the four Cantalupensis cultivars. Within the group Charentais melons, the differences between the short, mid and long shelf-life cultivars were considerable. 1H NMR analysis led to the quantification of 12 core amino acids, their levels were 3–10-fold greater in the Charentais melons, although they were reduced in the highly fragrant cv. Cézanne, indicating their role as VOC precursors. This study along with comparisons to more traditional labour intensive solid phase micro-extraction (SPME) GC–MS VOC profiling data has indicated that the high-throughput PDMS method is of great potential for the assessment of melon aroma and quality.
Dynamics of nitrogen oxides and ozone above and within a mixed hardwood forest in Northern Michigan
Seok, B. ; Helmig, D. ; Ganzeveld, L.N. ; Williams, W. ; vogel, C.S. - \ 2013
Atmospheric Chemistry and Physics 13 (2013). - ISSN 1680-7316 - p. 7301 - 7320.
reactive oxidized nitrogen - volatile organic-compounds - nitric-acid photolysis - biogenic nox emissions - gas-phase chemistry - dry deposition - atmospheric chemistry - tropospheric ozone - global-model - canopy
The dynamic behavior of nitrogen oxides (NOx=NO+NO2) and ozone (O3) above and within the canopy at the University of Michigan Biological Station AmeriFlux (UMBS Flux) site was investigated by continuous multi-height vertical gradient measurements during the summer and the fall of 2008. A daily maximum in nitric oxide (NO) mixing ratios was consistently observed during the morning hours between 06:00 and 09:00 EST above the canopy. Daily NO maxima ranged between 0.1 and 2 ppbv (with a median of 0.3 ppbv), which were 2 to 20 times above the atmospheric background. The sources and causes of the morning NO maximum were evaluated using NOx and O3 measurements and synoptic and micrometeorological data. Numerical simulations with a multi-layer canopy-exchange model were done to further support this analysis. The observations indicated that the morning NO maximum was caused by the photolysis of NO2 from non-local air masses, which were transported into the canopy from aloft during the morning breakup of the nocturnal boundary layer. The analysis of simulated process tendencies indicated that the downward turbulent transport of NOx into the canopy compensates for the removal of NOx through chemistry and dry deposition. The sensitivity of NOx and O3 concentrations to soil and foliage NOx emissions was also assessed with the model. Uncertainties associated with the emissions of NOx from the soil or from leaf-surface nitrate photolysis did not explain the observed diurnal behavior in NOx (and O3) and, in particular, the morning peak in NOx mixing ratios. However, a 30% increase in early morning NOx and NO peak mixing ratios was simulated when a foliage exchange NO2 compensation point was considered. This increase suggests the potential importance of leaf-level, bidirectional exchange of NO2 in understanding the observed temporal variability in NOx at UMBS.
Differentiation of specialty coffees by proton transfer reaction-mass spectrometry
Özdestan, Ö. ; Ruth, S.M. van; Alewijn, M. ; Koot, A.H. ; Romano, A. ; Cappelin, L. ; Biasioli, F. - \ 2013
Food Research International 53 (2013)1. - ISSN 0963-9969 - p. 433 - 439.
near-infrared spectroscopy - volatile organic-compounds - geographical origin - roasted coffee - ptr-ms - gas-chromatography - authentication - discrimination - products - identification
In the coffee sector a diversity of certifications is available, with the most well-known being organic and fair trade. Intrinsic markers of products may help to assure the authenticity of food products and complement administrative controls. In the present study 110 market coffees with special production traits were characterized by high sensitivity proton transfer reaction mass spectrometry (HS PTR-MS) and volatiles were tentatively identified by PTR-time of flight MS. Espresso coffees, Kopi Luwak coffee and organic coffees could be distinguished by their profiles of volatile compounds with the help of chemometrics. A PLS-DA classification model was estimated to classify the organic and regular coffees by their HS PTR-MS mass spectra. Cross validation showed correct prediction of 42 out of the 43 (98%) organic coffee samples and 63 out of the 67 (95%) regular coffee samples. Therefore, the presented strategy is a promising approach to rapid organic coffee authentication.
Intensive measurements of gas, water, and energy exchange between vegetation and troposhere during the MONTES campaign in a vegetation gradient from short semi-desertic shrublands to tall wet temperate forests in the NW Mediterranean Basin
Penuelas, J. ; Guenther, A. ; Rapparini, F. ; Llusia, J. ; Vilà-Guerau De Arellano, J. - \ 2013
Atmospheric Environment 75 (2013). - ISSN 1352-2310 - p. 348 - 364.
volatile organic-compounds - tethered balloon measurements - atmospheric boundary-layer - isoprene emission - quercus-ilex - biogenic emissions - particle formation - pinus-halepensis - field conditions - barcelona area
MONTES (“Woodlands”) was a multidisciplinary international field campaign aimed at measuring energy, water and especially gas exchange between vegetation and atmosphere in a gradient from short semi-desertic shrublands to tall wet temperate forests in NE Spain in the North Western Mediterranean Basin (WMB). The measurements were performed at a semidesertic area (Monegros), at a coastal Mediterranean shrubland area (Garraf), at a typical Mediterranean holm oak forest area (Prades) and at a wet temperate beech forest (Montseny) during spring (April 2010) under optimal plant physiological conditions in driest-warmest sites and during summer (July 2010) with drought and heat stresses in the driest–warmest sites and optimal conditions in the wettest–coolest site. The objective of this campaign was to study the differences in gas, water and energy exchange occurring at different vegetation coverages and biomasses. Particular attention was devoted to quantitatively understand the exchange of biogenic volatile organic compounds (BVOCs) because of their biological and environmental effects in the WMB. A wide range of instruments (GC–MS, PTR-MS, meteorological sensors, O3 monitors,…) and vertical platforms such as masts, tethered balloons and aircraft were used to characterize the gas, water and energy exchange at increasing footprint areas by measuring vertical profiles. In this paper we provide an overview of the MONTES campaign: the objectives, the characterization of the biomass and gas, water and energy exchange in the 4 sites-areas using satellite data, the estimation of isoprene and monoterpene emissions using MEGAN model, the measurements performed and the first results. The isoprene and monoterpene emission rates estimated with MEGAN and emission factors measured at the foliar level for the dominant species ranged from about 0 to 0.2 mg m-2 h-1 in April. The warmer temperature in July resulted in higher model estimates from about 0 to ca. 1.6 mg m-2 h-1 for isoprene and ca. 4.5 mg m-2 h-1 for monoterpenes, depending on the site vegetation and footprint area considered. There were clear daily and seasonal patterns with higher emission rates and mixing ratios at midday and summer relative to early morning and early spring. There was a significant trend in CO2 fixation (from 1 to 10 mg C m-2 d-1), transpiration (from 1–5 kg C m-2 d-1), and sensible and latent heat from the warmest–driest to the coolest–wettest site. The results showed the strong land-cover-specific influence on emissions of BVOCs, gas, energy and water exchange, and therefore demonstrate the potential for feed-back to atmospheric chemistry and climate
Effects of plant species identity, diversity and soil fertility on biodegradation of phenanthrene in soil
Oyelami, A.O. ; Okere, U.V. ; Orwin, K. ; Deyn, G.B. de; Jones, K.C. ; Semple, K.T. - \ 2013
Environmental Pollution 173 (2013). - ISSN 0269-7491 - p. 231 - 237.
polycyclic aromatic-hydrocarbons - volatile organic-compounds - microbial communities - grassland communities - contact time - rhizosphere - bioavailability - mineralization - pahs - microorganisms
The work presented in this paper investigated the effects of plant species composition, species diversity and soil fertility on biodegradation of 14C-phenanthrene in soil. The two soils used were of contrasting fertility, taken from long term unfertilised and fertilised grassland, showing differences in total nitrogen content (%N). Plant communities consisted of six different plant species: two grasses, two forbs, and two legume species, and ranged in species richness from 1 to 6. The degradation of 14C-phenanthrene was evaluated by measuring indigenous catabolic activity following the addition of the contaminant to soil using respirometry. Soil fertility was a driving factor in all aspects of 14C-phenanthrene degradation; lag phase, maximum rates and total extents of 14C-phenanthrene mineralisation were higher in improved soils compared to unimproved soils. Plant identity had a significant effect on the lag phase and extents of mineralisation. Soil fertility was the major influence also on abundance of microbial communities.
Impact of the Manaus urban plume on trace gas mixing ratios near the surface in the Amazon Basin: Implications for the NO-NO2-O-3 photostationary state and peroxy radical levels
Trebs, I. ; Mayol-Bracero, O.L. ; Pauliquevis, T. ; Kuhn, U. ; Sander, R. ; Ganzeveld, L.N. ; Meixner, F.X. ; Kesselmeier, J. ; Artaxo, P. ; Andreae, M.O. - \ 2012
Journal of Geophysical Research: Atmospheres 117 (2012). - ISSN 2169-897X - 16 p.
volatile organic-compounds - photochemical steady-state - reactive nitrogen-oxides - tropical rain-forest - chemistry box model - boundary-layer - atmospheric chemistry - dry season - airborne measurements - hydroxyl radicals
We measured the mixing ratios of NO, NO2, O-3, and volatile organic carbon as well as the aerosol light-scattering coefficient on a boat platform cruising on rivers downwind of the city of Manaus (Amazonas State, Brazil) in July 2001 (Large-Scale Biosphere-Atmosphere Experiment in Amazonia-Cooperative LBA Airborne Regional Experiment-2001). The dispersion and impact of the Manaus plume was investigated by a combined analysis of ground-based (boat platform) and airborne trace gas and aerosol measurements as well as by meteorological measurements complemented by dispersion calculations (Hybrid Single-Particle Lagrangian Integrated Trajectory model). For the cases with the least anthropogenic influence (including a location in a so far unexplored region similar to 150 km west of Manaus on the Rio Manacapuru), the aerosol scattering coefficient, sigma(s), was below 11 Mm(-1), NOx mixing ratios remained below 0.6 ppb, daytime O-3 mixing ratios were mostly below 20 ppb and maximal isoprene mixing ratios were about 3 ppb in the afternoon. The photostationary state (PSS) was not established for these cases, as indicated by values of the Leighton ratio, Phi, well above unity. Due to the influence of river breeze systems and other thermally driven mesoscale circulations, a change of the synoptic wind direction from east-northeast to south-southeast in the afternoon often caused a substantial increase of ss and trace gas mixing ratios (about threefold for sigma(s), fivefold for NOx, and twofold for O-3), which was associated with the arrival of the Manaus pollution plume at the boat location. The ratio F reached unity within its uncertainty range at NOx mixing ratios of about 3 ppb, indicating "steady-state" conditions in cases when radiation variations, dry deposition, emissions, and reactions mostly involving peroxy radicals (XO2) played a minor role. The median midday/afternoon XO2 mixing ratios estimated using the PSS method range from 90 to 120 parts per trillion (ppt) for the remote cases (sigma(s) <11 Mm(-1) and NOx <0.6 ppb), while for the polluted cases our estimates are 15 to 60 ppt. These values are within the range of XO2 estimated by an atmospheric chemistry box model (Chemistry As A Box model Application-Module Efficiently Calculating the Chemistry of the Atmosphere (CAABA/MECCA)-3.0).
Case study of the diurnal variability of chemically active species with respect to boundary layer dynamics during DOMINO
Stratum, B.J.H. van; Vilà-Guerau de Arellano, J. ; Ouwersloot, H.G. ; Dries, K. van den; Laar, T.W. van; Martinez, M. ; Lelieveld, J. ; Diesch, J.M. ; Drewnick, F. ; Fischer, H. ; Hosaynali Beygi, Z. ; Harder, H. ; Regelin, E. ; Sinha, V. ; Adame, J.A. ; Sörgel, M. ; Sander, R. ; Bozem, H. ; Song, W. ; Williams, J. ; Yassaa, N. - \ 2012
Atmospheric Chemistry and Physics 12 (2012). - ISSN 1680-7316 - p. 5329 - 5341.
volatile organic-compounds - tropical forest - oh reactivity - isoprene - chemistry - campaign - air - segregation - turbulence - gabriel
We study the interactions between atmospheric boundary layer (ABL) dynamics and atmospheric chemistry using a mixed-layer model coupled to chemical reaction schemes. Guided by both atmospheric and chemical measurements obtained during the DOMINO (Diel Oxidant Mechanisms in relation to Nitrogen Oxides) campaign (2008), numerical experiments are performed to study the role of ABL dynamics and the accuracy of chemical schemes with different complexity: the Model for Ozone and Related chemical Tracers, version 4 (MOZART-4) and a reduced mechanism of this chemical system. Both schemes produce satisfactory results, indicating that the reduced scheme is capable of reproducing the O3-NOx-VOC-HOx diurnal cycle during conditions characterized by a low NOx regime and small O3 tendencies (less than 1 ppb per hour). By focusing on the budget equations of chemical species in the mixedlayer model, we show that for species like O3, NO and NO2, the influence of entrainment and boundary layer growth is of the same order as chemical production/loss. This indicates that an accurate representation of ABL processes is crucial in understanding the diel cycle of chemical species. By comparing the time scales of chemical reactive species with the mixing time scale of turbulence, we propose a classification based on the Damk¨ohler number to further determine the importance of dynamics on chemistry during field campaigns. Our findings advocate an integrated approach, simultaneously solving the ABL dynamics and chemical reactions, in order to obtain a better understanding of chemical pathways and processes and the interpretation of the results obtained during measurement campaigns.
Forests under climate change and air pollution: Gaps in understanding and future directions for research
Matyssek, R. ; Wieser, G. ; Calfapietra, C. ; Vries, W. de; Mohren, G.M.J. - \ 2012
Environmental Pollution 160 (2012). - ISSN 0269-7491 - p. 57 - 65.
beech fagus-sylvatica - volatile organic-compounds - ozone risk-assessment - trace-gas-exchange - land-carbon sink - co2 and/or o-3 - nitrogen deposition - surface ozone - elevated co2 - temperate forests
Forests in Europe face significant changes in climate, which in interaction with air quality changes, may significantly affect forest productivity, stand composition and carbon sequestration in both vegetation and soils. Identified knowledge gaps and research needs include: (i) interaction between changes in air quality (trace gas concentrations), climate and other site factors on forest ecosystem response, (ii) significance of biotic processes in system response, (iii) tools for mechanistic and diagnostic understanding and upscaling, and (iv) the need for unifying modelling and empirical research for synthesis. This position paper highlights the above focuses, including the global dimension of air pollution as part of climate change and the need for knowledge transfer to enable reliable risk assessment. A new type of research site in forest ecosystems (“supersites”) will be conducive to addressing these gaps by enabling integration of experimentation and modelling within the soil-plant-atmosphere interface, as well as further model development. --------------------------------------------------------------------------------
Regionalizing global climate models
Pitman, A.J. ; Arneth, A. ; Ganzeveld, L.N. - \ 2012
International Journal of Climatology 32 (2012)3. - ISSN 0899-8418 - p. 321 - 337.
land-cover change - volatile organic-compounds - carbon-nitrogen interactions - isoprene emissions - particle formation - amazonian deforestation - tropical deforestation - biogenic hydrocarbons - maximum temperature - vegetation model
Global climate models simulate the Earth's climate impressively at scales of continents and greater. At these scales, large-scale dynamics and physics largely define the climate. At spatial scales relevant to policy makers, and to impacts and adaptation, many other processes may affect regional and local climate and perhaps trigger teleconnections that provide significant feedbacks on the global climate. These processes include fire, irrigation, land cover change (including crops and urban landscapes), and the emissions of biogenic volatile organic compounds by vegetation. Many of these interact within the atmosphere via dynamical, physical, and chemical mechanisms that lead to boundary-layer feedbacks. It is unlikely that any of these processes have a significant global-scale impact on the Earth's climate in the sense that the amount of warming due to a doubling of well mixed greenhouse gases would change if these processes were explicitly represented in climate models. These phenomena are usually local in space (e.g. urban) or in time (e.g. fire) and probably do not provide the on-going and sustained forcing to affect the global climate. However, for most impacts and adaptation research it is the regional and local climate that defines climate risk. At these scales, processes missing in climate models can have a substantially larger local-scale impact than the additional radiative forcing due to increasing greenhouse gases. Thus, while climate models are well designed for global and continental scales they exclude a suite of important processes that are locally and/or regionally important. We review these missing processes and highlight the research required to resolve the representation of these regional-scale processes in climate models. We also discuss the experimental methodology required to rigorously determine whether these processes are restricted to a local or regional-scale role or whether they do trigger robust teleconnections that would demonstrate global-scale significance
Typicality and Geographical Origin Markers of Protected Origin Cheese from The Netherlands Revealed by PTR-MS
Galle, S.A. ; Koot, A.H. ; Soukoulis, C. ; Cappellin, L. ; Biasioli, F. ; Alewijn, M. ; Ruth, S.M. van - \ 2011
Journal of Agricultural and Food Chemistry 59 (2011)6. - ISSN 0021-8561 - p. 2554 - 2563.
reaction-mass-spectrometry - volatile organic-compounds - flavor compounds - fragmentation patterns - profile - fraction - water - taste
Volatile fingerprints of 30 cumin cheese samples of artisanal farmers' cheese of Leiden with EU Protected Designation of Origin (PDO) and 29 cumin cheese samples of varying commercial Dutch brands without PDO protection were used to develop authentication models. The headspace concentrations of the volatiles, as measured with high sensitivity proton-transfer mass spectrometry, were subsequently subjected to partial least-squares discriminant analysis (PLS-DA). Farmers' cheese of Leiden showed a distinct volatile profile with 27 and 9 out of the 60 predominant ions showing respectively significantly higher and lower concentrations in the headspace of the cheese in comparison to the other cumin cheeses. The PLS-DA prediction models developed classified in cross-validation 96% of the samples of PDO protected, artisanal farmers' cheese of Leiden correctly, against 100% of commercial cumin cheese samples. The characteristic volatile compounds were tentatively identified by PTR-time-of-flight-MS. A consumer test indicated differences in appreciation, overall flavor intensity, creaminess, and firmness between the two cheese groups. The consumers' appreciation of the cumin cheese tested was not influenced by the presence of a name label or PDO trademark.
Can a 'state of the art' chemistry transport model really simulate Anazonian tropospheric chemistry
Barkley, M. ; Palmer, P.I. ; Ganzeveld, L.N. - \ 2011
Journal of Geophysical Research: Atmospheres 116 (2011). - ISSN 2169-897X - 28 p.
tropical rain-forest - volatile organic-compounds - terrestrial isoprene emissions - master chemical mechanism - planetary boundary-layer - mcm v3 part - atmospheric chemistry - nonmethane hydrocarbons - united-states - north-america
We present an evaluation of a nested high-resolution Goddard Earth Observing System (GEOS)-Chem chemistry transport model simulation of tropospheric chemistry over tropical South America. The model has been constrained with two isoprene emission inventories: (1) the canopy-scale Model of Emissions of Gases and Aerosols from Nature (MEGAN) and (2) a leaf-scale algorithm coupled to the Lund-Potsdam-Jena General Ecosystem Simulator (LPJ-GUESS) dynamic vegetation model, and the model has been run using two different chemical mechanisms that contain alternative treatments of isoprene photo-oxidation. Large differences of up to 100 Tg C yr-1 exist between the isoprene emissions predicted by each inventory, with MEGAN emissions generally higher. Based on our simulations we estimate that tropical South America (30–85°W, 14°N–25°S) contributes about 15–35% of total global isoprene emissions. We have quantified the model sensitivity to changes in isoprene emissions, chemistry, boundary layer mixing, and soil NOx emissions using ground-based and airborne observations. We find GEOS-Chem has difficulty reproducing several observed chemical species; typically hydroxyl concentrations are underestimated, whilst mixing ratios of isoprene and its oxidation products are overestimated. The magnitude of model formaldehyde (HCHO) columns are most sensitive to the choice of chemical mechanism and isoprene emission inventory. We find GEOS-Chem exhibits a significant positive bias (10–100%) when compared with HCHO columns from the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) and Ozone Monitoring Instrument (OMI) for the study year 2006. Simulations that use the more detailed chemical mechanism and/or lowest isoprene emissions provide the best agreement to the satellite data, since they result in lower-HCHO columns
The summertime Boreal forest field measurement intensive (HUMPPA-COPEC-2010): an overview of meteorological and chemical influences
Williams, J. ; Crowley, J. ; Fischer, H. ; Harder, H. ; Martinez, M. ; Ouwersloot, H.G. ; Vilà-Guerau de Arellano, J. ; Ganzeveld, L.N. ; Lelieveld, J. - \ 2011
Atmospheric Chemistry and Physics 11 (2011)20. - ISSN 1680-7316 - p. 10599 - 10618.
volatile organic-compounds - gas chromatography/mass spectrometry - acid-water nucleation - tropical rain-forest - sulfuric-acid - scots pine - boundary-layer - natural aerosol - phase microextraction - atmospheric particles
This paper describes the background, instrumentation, goals, and the regional influences on the HUMPPACOPEC intensive field measurement campaign, conducted at the Boreal forest research station SMEAR II (Station for Measuring Ecosystem-Atmosphere Relation) in Hyyti¨al¨a, Finland from 12 July–12 August 2010. The prevailing meteorological conditions during the campaign are examined and contrasted with those of the past six years. Back trajectory analyses show that meteorological conditions at the site in 2010 were characterized by a higher proportion of southerly flow than in the other years studied. As a result the summer of 2010 was anomalously warm and high in ozone making the campaign relevant for the analysis of possible future climates. A comprehensive land use analysis, provided on both 5 and 50 km scales, shows that the main vegetation types surrounding the site on both the regional and local scales are: coniferous forest (Scots pine and/or Norway spruce); mixed forest (Birch and conifers); and woodland scrub (e.g. Willows, Aspen); indicating that the campaign results can be taken as representative of the Boreal forest ecosystem. In addition to the influence of biogenic emissions, the measurement site was occasionally impacted by sources other than vegetation. Specific tracers have been used here to identify the time periods when such sources have impacted the site namely: biomass burning (acetonitrile and CO), urban anthropogenic pollution (pentane and SO2) and the nearby Korkeakoski sawmill (enantiomeric ratio of chiral monoterpenes). None of these sources dominated the study period, allowing the Boreal forest summertime emissions to be assessed and contrasted with various other source signatures
On the segregation of chemical species in a clear boundary layer over heterogeneous land surfaces
Ouwersloot, H.G. ; Vilà-Guerau de Arellano, J. ; Heerwaarden, C.C. van; Ganzeveld, L.N. ; Krol, M.C. ; Lelieveld, J. - \ 2011
Atmospheric Chemistry and Physics 11 (2011). - ISSN 1680-7316 - p. 10681 - 10704.
large-eddy simulation - volatile organic-compounds - tropical rain-forest - atmospheric chemistry - deciduous forest - heat-flux - emission - campaign - scale - turbulence
Using a Large-Eddy Simulation model, we have systematically studied the inability of boundary layer turbulence to efficiently mix reactive species. This creates regions where the species are accumulated in a correlated or anti-correlated way, thereby modifying the mean reactivity. We quantify this modification by the intensity of segregation, IS, and analyse the driving mechanisms: heterogeneity of the surface moisture and heat fluxes, various background wind patterns and non-uniform isoprene emissions. The heterogeneous surface conditions are characterized by cool and wet forested patches with high isoprene emissions, alternated with warm and dry patches that represents pasture with relatively low isoprene emissions. For typical conditions in the Amazon rain forest, applying homogeneous surface forcings and in the absence of free tropospheric NOx, the isoprene- OH reaction rate is altered by less than 10 %. This is substantially smaller than the previously assumed IS of 50% in recent large-scale model analyses of tropical rain forest chemistry. Spatial heterogeneous surface emissions enhance the segregation of species, leading to alterations of the chemical reaction rates up to 20 %. The intensities of segregation are enhanced when the background wind direction is parallel to the borders between the patches and reduced in the case of a perpendicular wind direction. The effects of segregation on trace gas concentrations vary per species. For the highly reactive OH, the differences in concentration averaged over the boundary layer are less than 2% compared to homogeneous surface conditions, while the isoprene concentration is increased by as much as 12% due to the reduced chemical reaction rates. These processes take place at the sub-grid scale of chemistry transport models and therefore need to be parameterized.
Behavioural responses of Anopheles gambiae sensu stricto to components of human breath, sweat and urine depend on mixture composition and concentration
Qiu, Y.T. ; Smallegange, R.C. ; Loon, J.J.A. van; Takken, W. - \ 2011
Medical and Veterinary Entomology 25 (2011)3. - ISSN 0269-283X - p. 247 - 255.
volatile organic-compounds - l-lactic acid - yellow-fever mosquito - aedes-aegypti - malaria mosquito - gas-chromatography - mass-spectrometry - human skin - odor - attraction
Host-seeking behaviour of the anthropophilic malaria vector Anopheles gambiae sensu stricto (Diptera: Culicidae) is mediated predominantly by olfactory cues. Several hundreds of odour components have been identified from human emanations, but only a few have been proven to act as attractants or synergists in the host-seeking behaviour of female An. gambiae. In previous work, aromatics, alcohols and ketones in human odours were found to elicit electrophysiological activity in antennal olfactory neurons of female An. gambiae. However, the behavioural effects of these compounds have not been investigated. In this study, behavioural responses of female An. gambiae to components of human breath, urine and sweat at a series of concentrations, or a single concentration in the case of acetone, were examined in combination with ammonia and L-lactic acid in a dual-choice olfactometer. The results showed that at specific concentrations 4-ethylphenol, indole, 3-methyl-1-butanol and two ketones inhibited the attractive effect of a mixture of ammonia and lactic acid. Acetone on its own was not attractive; however, when combined with lactic acid, the binary mixture was attractive. When combined with ammonia, acetone inhibited the attractiveness exerted by ammonia alone. Dodecanol and dimethyldisulphide did not affect the attraction exerted by ammonia and lactic acid at any of the concentrations tested. By contrast, a human-specific armpit odour, 7-octenoic acid, augmented the attraction exerted by the combination of ammonia and lactic acid at a specific dosage.
Airborne pariculate matter from livestock production systems: A review of an air pollution problem
Cambra-Lopez, M. ; Aarnink, A.J.A. ; Zhao, Y. ; Calvet, S. ; Torres, A.G. - \ 2010
Environmental Pollution 158 (2010)1. - ISSN 0269-7491 - p. 1 - 17.
swine confinement buildings - space-charge system - dust concentration distribution - dose-response relationships - particle-size distribution - volatile organic-compounds - ventilated broiler houses - lung-function - respiratory symptoms - source apportionment
Livestock housing is an important source of emissions of particulate matter (PM). High concentrations of PM can threaten the environment, as well as the health and welfare of humans and animals. Particulate matter in livestock houses is mainly coarse, primary in origin, and organic; it can adsorb and contain gases, odorous compounds, and micro-organisms, which can enhance its biological effect. Levels of PM in livestock houses are high, influenced by kind of housing and feeding, animal type, and environmental factors. Improved knowledge on particle morphology, primarily size, composition, levels, and the factors influencing these can be useful to identify and quantify sources of PM more accurately, to evaluate their effects, and to propose adequate abatement strategies in livestock houses. This paper reviews the state-of-the-art of PM in and from livestock production systems. Future research to characterize and control PM in livestock houses is discussed. Control of particulate matter emissions, a major challenge to modern livestock production.
Variation in natural plant products and the attraction of bodyguards involved in indirect plant defense
Mumm, R. ; Dicke, M. - \ 2010
Canadian Journal of Zoology 88 (2010)7. - ISSN 0008-4301 - p. 628 - 667.
volatile organic-compounds - parasitoid diaeretiella-rapae - green leaf volatiles - solar ultraviolet-radiation - host microhabitat location - herbivore manduca-sexta - elevated carbon-dioxide - diachasmimorpha-longicaudata hymenoptera - campoletis-sonorensis hym
Plants can respond to feeding or egg deposition by herbivorous arthropods by changing the volatile blend that they emit. These herbivore-induced plant volatiles (HIPVs) can attract carnivorous natural enemies of the herbivores, such as parasitoids and predators, a phenomenon that is called indirect plant defense. The volatile blends of infested plants can be very complex, sometimes consisting of hundreds of compounds. Most HIPVs can be classified as terpenoids (e.g., (E)-ß-ocimene, (E,E)-a-farnesene, (E)-4,8-dimethyl-1,3,7-nonatriene), green leaf volatiles (e.g., hexanal, (Z)-3-hexen-1-ol, (Z)-3-hexenyl acetate), phenylpropanoids (e.g., methyl salicylate, indole), and sulphur- or nitrogen-containing compounds (e.g., isothiocyanates or nitriles, respectively). One highly intriguing question has been which volatiles out of the complex blend are the most important ones for the carnivorous natural enemies to locate “suitable host plants. Here, we review the methods and techniques that have been used to elucidate the carnivore-attracting compounds. Electrophysiological methods such as electroantennography have been used with parasitoids to elucidate which compounds can be perceived by the antennae. Different types of elicitors and inhibitors have widely been applied to manipulate plant volatile blends. Furthermore, transgenic plants that were genetically modified in specific steps in one of the signal transduction pathways or biosynthetic routes have been used to find steps in HIPV emission crucial for indirect plant defense. Furthermore, we provide an overview on biotic and abiotic factors that influence the emission of HIPVs and how this can affect the interactions between members of different trophic levels. Consequently, we review the progress that has been made in this exciting research field during the past 30 years since the first studies on HIPVs emerged and we highlight important issues to be addressed in the future.
Screening of transformation products in soils contaminated with unsymmetrical dimethylhydrazine using headspace SPME and GC-MS
Kenessov, B.N. ; Koziel, J.A. ; Grotenhuis, J.T.C. ; Carlsen, L. - \ 2010
Analytica Chimica Acta 674 (2010)1. - ISSN 0003-2670 - p. 32 - 39.
solid-phase microextraction - chromatography-mass spectrometry - volatile organic-compounds - gas-chromatography - olfactometry - air - 1,1-dimethylhydrazine - odorants
The paper describes a novel SPME-based approach for sampling and analysis of transformation products of highly reactive and toxic unsymmetrical dimethylhydrazine (UDMH) which is used as a fuel in many Russian, European, Indian, and Chinese heavy cargo carrier rockets. The effects of several parameters were studied to optimize analyte recovery. It was found that the 85 µm Carboxen/polydimethylsiloxane fiber coating provides the highest selectivity for selected UDMH transformation products. Optimal sampling/sample preparation parameters were determined to be 1-h soil headspace sampling time at 40 °C. The GC inlet temperature was optimized to 170 °C held for 0.1 min, then 1 °C s-1 ramp to 250 °C where it was held for 40 min. Temperature programing resulted in a fast desorption along with minimal chemical transformation in the GC inlet. SPME was very effective extracting UDMH transformation products from soil samples contaminated with rocket fuel. The use of SPME resulted in high sensitivity, speed, small labor consumption due to an automation and simplicity of use. It was shown that water addition to soil leads to a significant decrease of recovery of almost all target transformation products of UDMH. The use of SPME for sampling and sample preparation resulted in detection of the total of 21 new compounds that are relevant to the UDMH transformation in soils. In addition, the number of confirmed transformation products of UDMH increased from 15 to 27. This sampling/sample preparation approach can be recommended for environmental assessment of soil samples from areas affected by space rocket activity
Atmospheric composition change: Ecosystems-Atmosphere interactions
Fowler, D. ; Pilegaard, K. ; Sutton, M.A. ; Ambus, P. ; Raivonen, M. ; Duyzer, J. ; Simpson, D. ; Fagerli, H. ; Fuzzi, S. ; Schjoerring, J.K. ; Granier, C. ; Neftel, A. ; Isaksen, I.S.A. ; Laj, P. ; Maione, M. ; Monks, P.S. ; Burkhardt, J. ; Daemmgen, U. ; Neirynck, J. ; Personne, E. ; Wichink Kruit, R.J. ; Butterbach-Bahl, K. ; Flechard, C. ; Tuovinen, J.P. ; Coyle, M. ; Gerosa, G. ; Loubet, B. ; Altimir, N. ; Gruenhage, L. ; Ammann, C. ; Cieslik, S. ; Paoletti, E. ; Mikkelsen, T.N. ; Ro-Poulsen, H. ; Cellier, P. ; Cape, J.N. ; Horvath, L. ; Loreto, F. ; Niinemets, U. ; Palmer, P.I. ; Rinne, J. ; Misztal, P. ; Nemitz, E. ; Nilsson, D. ; Pryor, S. ; Gallagher, M.W. ; Vesala, T. ; Skiba, U. ; Brueggemann, N. ; Zechmeister-Boltenstern, S. ; Williams, J. ; O'Dowd, C. ; Facchini, M.C. ; Leeuw, G. de; Flossman, A. ; Chaumerliac, N. ; Erisman, J.W. - \ 2009
Atmospheric Environment 43 (2009)33. - ISSN 1352-2310 - p. 5193 - 5267.
volatile organic-compounds - relaxed eddy accumulation - dry deposition velocity - reaction mass-spectrometry - cloud condensation nuclei - gas-particle interactions - surface-exchange fluxes - nitric-oxide emissions - beech fagus-sylvatica - ozone risk-assessment
Ecosystems and the atmosphere: This review describes the state of understanding the processes involved in the exchange of trace gases and aerosols between the earth's surface and the atmosphere. The gases covered include NO, NO2, HONO, HNO3, NH3, SO2, DMS, Biogenic VOC, O-3, CH4, N2O and particles in the size range 1 nm-10 mu m including organic and inorganic chemical species. The main focus of the review is on the exchange between terrestrial ecosystems, both managed and natural and the atmosphere, although some new developments in ocean-atmosphere exchange are included. The material presented is biased towards the last decade, but includes earlier work, where more recent developments are limited or absent. New methodologies and instrumentation have enabled, if not driven technical advances in measurement. These developments have advanced the process understanding and upscaling of fluxes, especially for particles, VOC and NH3. Examples of these applications include mass spectrometric methods, such as Aerosol Mass Spectrometry (AMS) adapted for field measurement of atmosphere-surface fluxes using micrometeorological methods for chemically resolved aerosols. Also briefly described are some advances in theory and techniques in micrometeorology. For some of the compounds there have been paradigm shifts in approach and application of both techniques and assessment. These include flux measurements over marine surfaces and urban areas using micrometeorological methods and the up-scaling of flux measurements using aircraft and satellite remote sensing. The application of a flux-based approach in assessment of O-3 effects on vegetation at regional scales is an important policy linked development secured through improved quantification of fluxes. The coupling of monitoring, modelling and intensive flux measurement at a continental scale within the NitroEurope network represents a quantum development in the application of research teams to address the underpinning science of reactive nitrogen in the cycling between ecosystems and the atmosphere in Europe. Some important developments of the science have been applied to assist in addressing policy questions, which have been the main driver of the research agenda, while other developments in understanding have not been applied to their wider field especially in chemistry-transport models through deficiencies in obtaining appropriate data to enable application or inertia within the modelling community. The paper identifies applications, gaps and research questions that have remained intractable at least since 2000 within the specialized sections of the paper, and where possible these have been focussed on research questions for the coming decade. (C) 2009 Published by Elsevier Ltd.