Emission fluxes and atmospheric degradation of monoterpenes above a boreal forest: field measurements and modelling

The contribution of monoterpenes to aerosol formation processes within and above forests is not well understood. This is also true for the particle formation events observed during the BIOFOR campaigns in Hyytiälä, Finland. Therefore, the diurnal variation of the concentrations of several biogenic volatile organic compounds (BVOCs) and selected oxidation products in the gas and particle phase were measured on selected days during the campaigns in Hyytiälä, Finland. α-pinene and Δ3-carene were found to represent the most important monoterpenes above the boreal forest. A clear vertical gradient of their concentrations was observed together with a change of the relative monoterpene composition with height. Based on concentration profile measurements of monoterpenes, their fluxes above the forest canopy were calculated using the gradient approach. Most of the time, the BVOC fluxes show a clear diurnal variation with a maximum around noon. The highest fluxes were observed for α-pinene with values up to 20 ng m−2 s−1 in summer time and almost 100 ng m−2 s−1 during the spring campaign. Furthermore, the main oxidation products from α-pinene, pinonaldehyde, and from β-pinene, nopinone, were detected in the atmosphere above the forest. In addition to these more volatile oxidation products, pinic and pinonic acid were identified in the particle phase in a concentration range between 1 and 4 ng m−3. Beside these direct measurement of known oxidation products, the chemical sink term in the flux calculations was used to estimate the amount of product formation of the major terpenes (α-pinene, β-pinene, Δ3-carene). A production rate of very low volatile oxidation products (e.g., multifunctional carboxylic) from ·OH- and O3-reaction of monoterpenes of about 1.3·104 molecules cm−3 s−1 was estimated for daylight conditions during summer time. Additionally, model calculations with the one-dimensional multilayer model CACHE were carried out to investigate the diurnal course of BVOC fluxes and chemical degradation of terpenes

Heat and moisture budgets from airborne measurements and high-resolution model simulations

High-resolution simulations with a mesoscale model are performed to estimate heat and moisture budgets of a well-mixed boundary layer. The model budgets are validated against energy budgets obtained from airborne measurements over heterogeneous terrain in Western Germany. Time rate of change, vertical divergence, and horizontal advection for an atmospheric column of air are estimated. Results show that the time trend of specific humidity exhibits some deficiencies, while the potential temperature trend is matched accurately. Furthermore, the simulated turbulent surface fluxes of sensible and latent heat are comparable to the measured fluxes, leading to similar values of the vertical divergence. The analysis of different horizontal model resolutions exhibits improved surface fluxes with increased resolution, a fact attributed to a reduced aggregation effect. Scale-interaction effects could be identified: while time trends and advection are strongly influenced by mesoscale forcing, the turbulent surface fluxes are mainly controlled by microscale processes

Agrobacterium-mediated transformation systems of Primula vulgaris

Background: Genetic transformation is a valuable tool and an important procedure in plant functional genomics contributing to gene discovery, allowing powerful insights into gene function and genetically controlled characteristics. Primulaceae species provide one of the best-known examples of heteromorphic flower development, a breeding system which has attracted considerable attention, including that of Charles Darwin. Molecular approaches, including plant transformation give the best opportunity to define and understand the role of genes involved in floral heteromorphy in the common primrose, Primula vulgaris, along with other Primula species. Results: Two transformation systems have been developed in P. vulgaris. The first system, Agrobacterium-mediated vacuum infiltration of seedlings, enables the rapid testing of transgenes, transiently in planta. GUS expression was observed in the cotyledons, true leaves, and roots of Primula seedlings. The second system is based on Agrobacterium tumefaciens infection of pedicel explants with an average transformation efficiency of 4.6%. This transformation system, based on regeneration and selection of transformants within in vitro culture, demonstrates stable transgene integration and transmission to the next generation. Conclusion: The two transformation systems reported here will aid fundamental research into important traits in Primula. Although, stable integration of transgenes is the ultimate goal for such analyses, transient gene expression via Agrobacterium-mediated DNA transfer, offers a simple and fast method to analyse transgene functions. The second system describes, for the first time, stable Agrobacterium-mediated transformation of Primula vulgaris, which will be key to characterising the genes responsible for the control of floral heteromorphy

A novel post-processing algorithm for Halo Doppler lidars

Commercially available Doppler lidars have now been proven to be efficient tools for studying winds and turbulence in the planetary boundary layer. However, in many cases low signal-to-noise ratio is still a limiting factor for utilising measurements by these devices. Here, we present a novel post-processing algorithm for Halo Stream Line Doppler lidars, which enables an improvement in sensitivity of a factor of 5 or more. This algorithm is based on improving the accuracy of the instrumental noise floor and it enables longer integration times or averaging of high temporal resolution data to be used to obtain signals down to -32 dB. While this algorithm does not affect the measured radial velocity, it improves the accuracy of radial velocity uncertainty estimates and consequently the accuracy of retrieved turbulent properties. Field measurements using three different Halo Doppler lidars deployed in Finland, Greece and South Africa demonstrate how the new post-processing algorithm increases data availability for turbulent retrievals in the planetary boundary layer, improves detection of high-altitude cirrus clouds and enables the observation of elevated aerosol layers.Peer reviewe

Towards OOPCTE

Based on the 'Object-oriented Database System Manifesto', we propose an object-oriented extension of PCTE, to migrate smoothly from the current PCTE towards a fully object-oriented PCTE. Our approach is focused on modelling behavior of objects and provides better support for fine grained objects. We suggest an extension to the PCTE OMS data model, which could be either realized as a layer on top of PCTE or included into the kernel of PCTE in the future. (orig.)Available from TIB Hannover: RR 9963(7) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Entstehung, Verhalten und Ablagerung von gas-, partikel und tropfenfoermigen Reaktionsprodukten Abschlussbericht

Es wurden vergleichende Studien zur Deposition und Emission sowie zur Stoffumwandlung im Gebiet des Nationalparks Bayerischer Wald durchgefuehrt. Die Ergebnisse zeigen, dass die Stoffeintraege durch trockene Deposition diejenigen durch nasse Deposition uebertreffen. Bei dem Saeureeintrag sowie dem Eintrag von Sulfat kommt den Prozessen der Codeposition (d.h. der reaktiven Ablagerung von SO_2) eine dominierende Rolle zu. Da die verschiedenen Vorgaenge recht komplex miteinander verknuepft sind, wurde vorerst nur eine Berechnung des minimalen Eintrags durch trockene Deposition durchgefuehrt. Diese ergibt, dass der gesamte Nitrateintrag mindestens 9,0 kgNha"-"1a"0"1, der gesamte Ammoniumeintrag mindestens etwa 16 kgNha"-"1a"-"1, der H"+-Eintrag etwa 2,0 kgH"+ha"-"1a"-"1 und der Sulfateintrag etwa 66 kgSO_4"2"-ha"-"1a"-"1 betraegt. Wird die trockene NO_2-Deposition als Nitrateintrag bewertet, so erhoeht sich dieser auf ca. 14 kgNha"-"1a"-"1. Wichtig erscheint dabei, dass wesentliche Beitraege zur trockenen H"+ und SO_4"2"--Deposition durch Prozesse der Codeposition erfolgen. Diese Vorgaenge werden offensichtlich i.a. deutlich unterschaetzt. In Regionen, in denen nur eine H_2O_2Produktion von 0,1 ppbh"-"1 stattfindet, kann durch Codeposition mit H_2O_2 ein jaehrlicher Sulfatfluss von ca. 20 kgha"-"1a"-"1 erzeugt werden. Durch Codeposition von SO_2 mit O_3 werden ca. 17-20 kgha"-"1a"-"1 gebildet. Es konnte ferner gezeigt werden, dass chemische Reaktionen in der Gas- und Partikelphase signifikant die Stoffbilanzen und damit auch die Stoffdeposition beeinflussen koennen. Die NHO_3-Bildung vermag sogar tagsueber durch die Radikalreaktion von NO_3+NO_2 beeinflusst zu werden, da die Photolyseraten im Bestand gegenueber den Werten in der Atmosphaehre stark reduziert sind. (orig.)Various studies were performed in the Nationalpark 'Bavarian Forest' at a spruce/beech forest-site to determine the fluxes of N- and S-compounds by dry and wet deposition. The minimum deposition is determined for nitrate 9.0 kgNha"-"1yr"-"1, for ammonium (NH_4"++NH_3) 16 kgNha"-"1yr"-"1, for H"+ 2.0 kgH"+ha"-"1yr"-"1 and for sulfate 66 kgSO_2"2"-ha"-"1yr"-"1. If the dry deposition of NO_2 is considered to contribute to the nitrate-deposition, the total 'nitrate' deposition increases up to about 14 kgNha"-"1yr"-"1. It is important to mention that the processes of co-deposition (e.g. reactive deposition of SO_2 with O_3 or/and H_2O_2) at the needles/leaves and at the soil surface considerable contribute to the total deposition of H"+ and sulfate. Even in regions with H_2O_2-production rates of 0.1 ppb h"-"1 (Dlugi, 1993) a minimum flux of sulfate of 0.07 #mu#gm"-"2s"-"1 can be produced by the process of codeposition resulting in an effective reduction of surface resistance of SO_2 by the surface reaction SO_2+H_2O_2. This is equivalent to a sulfate flux of about 10 kgha"-"1yr"-"1. In addition, by the surface reaction of SO_2 and O_3 again the effective surface resistance is lowered and this contributes to sulfate deposition by about 17-20 kgha"-"1yr"-"1. Also fluxes of NH_3 from the forest to the atmosphere are observed which show a contribution of direct emission from trees below-10-15% of the total emission. The remaining contribution (e.g. 90-85%) at this site mainly results from dissociation of ammonium nitrate in the crown region during daytime. The HNO_3-formation inside the canopy from the reaction NO_3+NO_2 is possible as the photodissociation of NO_3 inside the forste with LAI>5 (Leave Area Index) is small compared to the atmosphere even during daytime. (orig.)SIGLEAvailable from TIB Hannover: RR 8418(95-S1)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman