Development of a Bioaerosol single particle detector (BIO IN) for the Fast Ice Nucleus CHamber FINCH

In this work we present the setup and first tests of our new BIO IN detector. This detector was constructed to classify atmospheric ice nuclei (IN) for their biological content. It is designed to be coupled to the Fast Ice Nucleus CHamber FINCH. If one particle acts as an ice nucleus, it will be at least partly covered with ice at the end of the development section of the FINCH chamber. The device combines an auto-fluorescence detector and a circular depolarization detector for simultaneous detection of biological material and discrimination between water droplets, ice crystals and non activated large aerosol particles. The excitation of biological material with UV light and analysis of auto-fluorescence is a common principle used for flow cytometry, fluorescence microscopy, spectroscopy and imaging. The detection of auto-fluorescence of airborne single particles demands some more experimental effort. However, expensive commercial sensors are available for special purposes, e.g. size distribution measurements. But these sensors will not fit the specifications needed for the FINCH IN counter (e.g. high sample flow of up 10 LPM). The newly developed -low cost- BIO IN sensor uses a single high-power UV LED for the electronic excitation instead of much more expensive UV lasers. Other key advantages of the new sensor are the low weight, compact size, and the little effect on the aerosol sample, which allows it to be coupled with other instruments for further analysis. The instrument will be flown on one of the first missions of the new German research aircraft "HALO" (High Altitude and LOng range)

Development of a bioaerosol single particle detector (BIO IN) for the fast ice nucleus chamber FINCH [Discussion paper]

In this work we present the setup and first tests of our new BIO IN detector. This detector is designed to classify atmospheric ice nuclei (IN) for their biological content. Biological material is identified via its auto-fluorescence (intrinsic fluorescence) after irradiation with UV radiation. Ice nuclei are key substances for precipitation development via the Bergeron–Findeisen process. The level of scientific knowledge regarding origin and climatology (temporal and spatial distribution) of IN is very low. Some biological material is known to be active as IN even at relatively high temperatures of up to –2°C (e.g. pseudomonas syringae bacteria). These biological IN could have a strong influence on the formation of clouds and precipitation. We have designed the new BIO IN sensor to analyze the abundance of IN of biological origin. The instrument will be flown on one of the first missions of the new German research aircraft ''HALO'' (High Altitude and LOng Range)

Aitken particle size distribution in the Atlantic north east trade winds

The Aitken particle size distribution in background aerosols was measured with a newly developed Diffusion Analyzer System. The measuring system and the inversion method is discussed critically. The several hundreds of measurements indicate that several maxima in the size distribution are present. Particles as small as 10-3 µm in radius are constantly observed. Measurements of other authors indicate similar results

Messungen der Aerosolgrößenverteilung über dem Atlantik

During the third part of the Atlantic Expedition 1969 from 10° S to 60° N along 30 ° W, measurements of the complete size distribution of atmospheric aerosols over the whole size range from about 10-7 to 10-2 cm radius were made. This was possible by the simultaneous operation of different methods which are critically discussed. The results obtained are the first of its kind and are of general interest despite some methodical shortcomings. North of the equator the ship passed through air masses of West African origin and the influence of Sahara dust on the marine aerosols could be documented in a unique way. The Sahara dust component was restricted to the size range of 10-5 to 10-3 cm radius. Throughout the voyage particles up to 10-2 cm radius were always found to be present, similar to findings over continents. Of special interest is the observation that the size distribution extends to very small particles, suggesting continuous aerosol production over the ocean

The Long-Range Transport of Mineral Aerosols: Group Report

International audienc

Size distribution, mass concentration, chemical and mineralogical composition, and derived optical parameters of the boundary layer aerosol at Tinfou, Morocco, during SAMUM 2006

During the SAMUM 2006 field campaign in southern Morocco, physical and chemical properties of desert aerosols were measured. Mass concentrations ranging from 30 �¼g m-3 for PM2.5 under desert background conditions up to 300,000 �¼g m-3 for total suspended particles (TSP) during moderate dust storms were measured. TSP dust concentrations are correlated with the local wind speed, whereas PM10 and PM2.5 concentrations are determined by advection from distant sources. Size distributions were measured for particles between 20 nm and 500 �¼m diameter (parameterizations are given). Two major regimes of the size spectrum can be distinguished. Smaller than 500 nm particle diameter, the distributions show maxima around 80 nm, widely unaffected of varying meteorological and dust emission conditions. For particles larger than 500 nm, the range of variation may be up to one order of magnitude and up to three orders of magnitude for particles larger than 10 �¼m. The mineralogical composition of aerosol bulk samples was measured by X-ray powder diffraction. Major constituents of the aerosol are quartz, potassium feldspar, plagioclase, calcite, hematite, and the clay minerals illite, kaolinite, and chlorite. A small temporal variability of the bulk mineralogical composition was encountered. The chemical composition of approximately 74,000 particles was determined by electron microscopic single particle analysis. Three size regimes are identified: Smaller than 500 nm in diameter, the aerosol consists of sulfates and mineral dust. Larger than 500 nm up to 50 �¼m, mineral dust dominates, consisting mainly of silicates, and â�� to a lesser extent â�� carbonates and quartz. Larger than 50 �¼m, approximately half of the particles consist of quartz. Time series of the elemental composition show a moderate temporal variability of the major compounds. Calcium-dominated particles are enhanced during advection from a prominent dust source in Northern Africa (Chott El Djerid and surroundings). The particle aspect ratio was measured for all analyzed particles. Its size dependence reflects that of the chemical composition. Larger than 500 nm particle diameter, a median aspect ratio of 1.6 is measured. Towards smaller particles, it decreases to about 1.3 (parameterizations are given). From the chemical/mineralogical composition, the aerosol complex refractive index was determined for several wavelengths from ultraviolet to near infrared. Both real and imaginary parts show lower values for particles smaller than 500 nm diameter (1.55â��2.8��10-3i at 530 nm) and slightly higher values for larger particles (1.57â��58 3.7��10-3i at 530 nm)

Christian Junge – a pioneer in global atmospheric chemistry

Christian Junge (1912–1996) is considered by many to be the founder of the modern discipline of atmospheric chemistry. In studies from the 1950s through the 1970s, Junge was able to link chemical measurements in a few scattered locations around the earth and integrate them with meteorology to develop the first global view of the basic chemical and physical processes that control the sources, transport, transformations, and fate of particles and gases in the atmosphere. In this paper we summarize and comment upon a number of Junge’s seminal research contributions to atmospheric chemistry, including his discovery of the stratospheric sulfate layer (known as the Junge layer), his recognition of the relationship between the variability of the concentrations of trace gases and their atmospheric lifetimes, his studies of aerosol size and number distributions, his development of the first quantitative model of tropospheric ozone, and other significant scientific investigations. We also discuss Junge’s professional life, his many international leadership positions and honors, as well as some memories and reflections on his many abilities that led to his outstanding contributions to the science of atmospheric chemistry

Bioaerosol field measurements: Challenges and perspectives in outdoor studies

Outdoor field measurements of bioaerosols are performed within a wide range of basic and applied scientific disciplines, each with its own goals, assumptions, and terminology. This paper contains brief reviews of outdoor field bioaerosol research from these diverse interests, with emphasis on perspectives from the atmospheric sciences. The focus is on a high level discussion of pressing scientific questions, grand challenges, and needs for cross-disciplinary collaboration. The research topics, in which bioaerosol field measurement are important, include (i) atmospheric physics, clouds, climate, and hydrological cycle; (ii) atmospheric chemistry; (iii) airborne allergen-containing particles; (iv) airborne human pathogens and national security; (v) airborne livestock and crop pathogens; and (vi) biogeography and biodiversity. We concisely review bioaerosol impacts and discuss properties that distinguish bioaerosols from abiological aerosols. We give extra focus to regions of specific interest, i.e. forests, polar regions, marine and coastal environments, deserts, urban and rural areas, and summarize key considerations related to bioaerosol measurements, such as of fluxes, long-range transport, and from both stationary and vessel-driven platforms. Keeping in mind a series of key scientific questions posed within the diverse communities, we suggest that pressing scientific questions include: (i) emission sources and flux estimates; (ii) spatial distribution; (iii) changes in distribution; (iv) atmospheric aging; (v) metabolic activity; (vi) urbanization of allergies; (vii) transport of human pathogens; and (viii) climate-relevant properties