Heikki Tervahattu

Experimental studies about the impact of traction sand on urban road dust composition

Traffic causes enhanced PM(10) resuspension especially during spring in the US, Japan, Norway, Sweden and Finland, among other countries. The springtime PM(10) consists primarily of mineral matter from tyre-induced paved road surface wear and traction sand. In some countries, the majority of vehicles are equipped with studded tyres to enhance traction, which additionally increases road surface wear. Because the traction sand and the mineral matter from the pavement aggregate can have a similar mineralogical composition, it has been difficult to determine the source of the mineral fraction in the PM(10). In this study, homogenous traction sand and pavement aggregate with different mineralogical compositions were chosen to determine the sources of PM(10) particles by single particle analysis (SEM/EDX). This study was conducted in a test facility, which made it possible to rule out dust contributions from other sources. The ambient PM(10) concentrations were higher when traction sand was used, regardless of whether the tyres were studded or not. Surprisingly, the use of traction sand greatly increased the number of the particles originating from the pavement. It was concluded that sand must contribute to pavement wear. This phenomenon is called the sandpaper effect. An understanding of this is important to reduce harmful effects of springtime road dust in practical winter maintenance of urban roads

Impact of unleaded gasoline introduction on the concentration of lead in the air of Dhaka, Bangladesh

Abstract Airborne particulate matter (APM) samples collected at a semiresidential area in Dhaka, Bangladesh, during the periods of 1994 and 1997–2000 have been studied to assess the impact of the use of unleaded gasoline in Bangladesh. According to scanning electron microscopy/energy-dispersive X-ray microanalyzer studies, lead (Pb) was found as Pb sulfates and Pb halides in motor-vehicle exhaust particles, whose diameters were some hundreds of nanometers. No significant changes in the annual averages of APM mass and black carbon concentrations have been observed over the period. The yearly average Pb concentration reached a maximum value of 370 ng/m3 in the particulate matter with an aerodynamic diameter < 2.5 µm fraction in 1998. In 2000, the concentration decreased to approximately one-third (106 ng/m3) of the high earlier values after the introduction of unleaded gasoline in 1999. A significant lowering of the blood Pb level of the population over next few years is expected as a result of this great decrease in Pb concentration.

Organic aerosols and the origin of life: an hypothesis.

Recent experimental work has verified the prediction that marine aerosols could have an exterior film of amphiphiles; palmitic, stearic and oleic acids were predominant. Thermodynamic analysis has revealed that such aerosols are energetically capable of asymmetric division. In a prebiotic terrestrial environment, one of the products of such aerosol fission would have been bacterially sized (microns), the other would have been virally sized (tens of nanometers). Plausible avenues for chemical differentiation between the two particles are discussed, and the probabilities for the transition from geochemistry to biochemistry updated in light of recent palaeo fossil studies.

Distribution of Airborne Particles from Multi-Emission Source

The purpose of this work was to study the distribution of airborne particles in the surroundings of an iron and steel factory in southern Finland. Several sources of particulate emissions are lying side by side, causing heavy dust loading to the environment. This complicated multi-pollutant situation was studied mainly by SEM/EDX methodology.Particles accumulated on Scots pine bark were identified andquantitatively measured according to their element content,size and shape. As a result, distribution maps of particulateelements were drawn and the amount of different particle typesalong the study lines was plotted. Particulate emissions fromthe industrial or energy production processes were not themain dust source. Most emissions were produced from theclinker crusher. Numerous stockpiles of the industrial wastesand raw materials also gave rise to particulate emissions as aresult of wind erosion. It was concluded that SEM/EDXmethodology is a useful tool for studying the distribution ofparticulate pollutants.

Chemistry in Prebiotic Aerosols: A Mechanism for the Origin of Life

Limnology and Environmental Protection. He obtained his Ph.D. in 1969 from the University of Oulu, Finland. Dr. Tervahattu is a Leader in the Urban Dust Project (UDP). The overall objective of the Project is to produce new knowledge about the composition and sources of urban particulate matter in order to improve air quality. His group is specialized to use electron microscopy and related methods in aerosol particle research. UDP was first focused to road dust, which cause health impacts every spring in Nordic countries. More recently, long-range transport (LRT) of aerosol particles has become the main object of UDP. In the LRT study of sea-salt particles, the group found particles, which had an organic surface layer composed mainly of fatty acids. This discovery was the reason why Dr. Tervahattu became interested about the origin of life and the theory of prebiotic aerosols as potential reactors in the chemical development. Email: heikki.tervahattu@helsinki.fi

Fatty acids on continental sulfate aerosol particles: FATTY ACID SURFACTANTS

Published 2005 American Geophysical Union. Reproduced by permission of American Geophysical Union.