Continental impact on marine boundary layer coarse particles over the Atlantic Ocean between Europe and Antarctica

Aerosol samples were collected in the Atlantic marine boundary layer between the English Channel and Antarctica during November–December 1999. The composition of coarse (aerodynamic diameter 1–3 μm) individual aerosol particles was studied using the SEM/EDX method. The major particle types observed were fresh sea salt, sea-salt particles reacted partly or totally with sulphuric acid or nitric acid, Mg-sulphate, Ca-sulphate, mixed aluminosilicates and sea salt, aluminosilicates, Ca-rich particles and Fe-rich particles. The relative fractions of sea-salt particles with moderate or strong Cl depletion were high near the coasts of Europe (65–74%) and Northern Africa (44–87%), low far from the coast of Western Africa (10–20%) and very low in remote sea areas between Africa and Antarctica (1%). The Cl depletion was strongest when air masses arrived from the direction of anthropogenic pollution sources. The fractions of Mg-sulphate particles were high (18–25%) in 2 samples near Europe. The Mg-sulphate particles were probably formed as a result of fractional recrystallization of sea-salt particles in which Cl was substituted by sulphate. It remained unclear whether these particles were formed in the atmosphere or during and after sampling. The relative fractions of particles from continental sources were quite low (10–15%) near Europe, very high (25–78%) near the coast of Northwestern Africa and very low in the remote sea areas (0–2%). Most of the continental particles were aluminosilicates and some of them were internally mixed with sea salt. Near the coast of Northwestern Africa, the main source of aluminosilicates was Saharan dust, and near the Gulf of Guinea, emissions from biomass burning were also mixed with aluminosilicates and sea salt.     

Geochemical Baselines of Nickel and Chromium in Various Surficial Materials in the Barents Region, NW Russia and Finland

The geochemical baselines of nickel and chromium were studied from the data produced by the Barents Ecogeochemistry project, a large international regional geochemical mapping exercise. The project surveyed major and trace element distributions in stream water, organic and mineralogically-modified soil horizons, and terrestrial moss in the northwestern part of Russia and in Finland. Other materials were collected during the pilot phase and later from thirty special sites. The results on respective materials by XRF, ICP-MS and ICP-AES showed that both geological and anthropogenic factors have an influence on the geochemical baseline concentrations of Ni and Cr in organic soil and stream water. The main explanation of the observed distribution patterns in terrestrial moss is human activity, but geological factors can also affect the baselines. The variation of geochemical baselines in the mineral-rich soil horizon depends only on variations in bedrock. The mineralogy of samples mainly controls the leachability properties of soil samples.     

Forecasting the HIV epidemic in Finland by using functional small area units

The purpose of this study is to analyze the development of the HIV epidemic in Finland in 1983–1994, and to predict the spatial distribution of new cases through 1997. The analysis is based on seroepidemiological data of all reported HIV carriers and a number of explaining variables based on individual level register data. Instead of focusing on populations of carriers and susceptibles, emphasis is placed on identifying the primary influences directing the epidemic as a spatial process. This is done by dividing Finland into 62 functional small area units and by assigning the risk of obtaining the virus to each unit based on behavioral, socioeconomic, interaction, and structural characteristics of the population. The approach is a multistep procedure including multivariate regression analysis, the potential model, and time series analysis. The model was used to produce a three-year forecast of the distribution of new HIV carriers in Finland. Compared with earlier studies of similar nature based on the use of administrative regional units, in this paper the forecast distribution of HIV cases is more closely related to the functional structure of the spatial system in Finland. Such an approach offers a method for producing more reliable short-term forecasts of the spatial distribution of new HIV cases. Three different spatial diffusion patterns were identified.     

Modelling the formation of H2SO4–H2O particles in rural, urban and marine conditions

The factors which affect the formation of new sulphuric acid particles in different atmospheric conditions are investigated. An atmospheric chemistry gas phase box model coupled to a three mode integral aerosol dynamics model is used. The simulations show the dependence of the concentration of nucleation mode particles on initial pre-existing particles, the intensity of UV radiation, the emissions of dimethylsulphide (DMS) and the ratio of emissions of hydrocarbons (HC) and NO_x present in the atmosphere. Eight different basic cases are simulated in urban, rural and marine conditions. The effects of pre-existing particles as a sink of sulphuric acid are clearly seen. The increased UV radiation is also seen to enhance particle formation via sulphuric acid route significantly.     

Depositional history of peatland pines (Pinus sylvestris L.) in NW Enontekiö, Finnish Lapland: implications for Middle Holocene drought and temperature fluctuations

High altitude and latitude findings of subfossil peatland pine trees were unearthed from the region of NW Finnish Lapland and dated by ¹⁴C and tree-ring methods. The depositional history of the trees illustrated two distinct peatland pine phases dated to Middle Holocene intervals 4900–4400 and 4100–3400 cal. a BC. It seems evident that both thermal and hydroclimatic fluctuations have played roles of varying importance in the establishment of this pine population and its demise. The presence of these pines, from a site ~60 km north of the coniferous timberline and conditions ~1 °C and 100 degree-days colder than those at the present-day timberline, concurs with previous studies demonstrating the association between the high-latitude summer-temperature cooling and circumpolar timberline retreat since the Middle Holocene due to Milankovitch forcing. On the other hand, the peatland pine recruitment was made possible by drier than present surface conditions during the previously reconstructed Middle Holocene drought anomaly (Hyvärinen-Alhonen event). Our data suggest this event was not continuous but reached its two-phase climax during the peatland pine phases, with an interruption of several centuries with moister surface conditions between 4400 and 4100 cal. a BC. The findings highlight the sensitivity of well-dated peatland tree assemblages in terms of recording past climatic evolution and events and the need for new collections from north and south Fennoscandia and the Baltic region, for more detailed analyses over extended time intervals and regions.     

Particle Size Distribution and Gas-Particle Partition of Polycyclic Aromatic Hydrocarbons in Helsinki Urban Area

Ambient concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured in Helsinki (Finland). Particle mass size distributions were obtained with a cascade impactor (12 stages) with glass fibre filters as substrates. Simultaneously with the impactor measurements, particulate and gaseous PAHs were collected on a quartz filter and XAD-2 adsorbent, respectively, for evaluation of gas-partition coefficients. Samples were analysed for PAHs by on-line coupled supercritical fluid extraction — liquid chromatography — gas chromatography — mass spectrometry. The impactor results showed that most of the PAHs in Helsinki urban area were concentrated in fine particles (<2.5 μm diameter) with unimode peak at about 1 μm. The results were comparable with the number distribution measured with a differential mobility particle sizer. Total amounts of PAHs (gas + particle) varied from 15 (acenaphthylene) to 1990 (fluorene) pg/m³. The PAHs lighter than 202 amu (pyrene and fluoranthene) were exclusively in gas phase, whereas those heavier than 202 amu were mostly associated with particles. A plot of the partition coefficients (logKp) versus the temperature dependent sub-cooled vapour pressures (logp _L ⁰ ) showed a gradient of −0.66, which deviated from equilibrium state (gradient = −1).     

The investigations of aerosol particle formation in urban background area of Helsinki

In this study the possible conditions for new aerosol particle formation in a background area of Helsinki have been analysed. The measurements of aerosol particle size distribution, main gaseous pollutant compounds, UV spectra and meteorological parameters were performed during April–May 1993. The main interest was concentrated on the investigations of photochemical OH radical formation, the oxidation of gas phase SO₂ to H₂SO₄ and the formation of H₂SO₄---H₂O aerosol particles. The measurements were analysed using a model for OH radical formation and aerosol dynamics. The analysis of aerosol size distributions was carried out using positive matrix factorization. The main conclusion is that based on our model analysis no evidence of new particle formation in the vicinity of the measurement station was found. However, the high concentrations of aerosol particles in the ultrafine size range indicate that some other particle formation pathways are to be considered.     

Power and influence tactics in the promotion of regional development: An empirical analysis of the work of Finnish regional development officers

Increased complexity and rapid pace of change demand more from people responsible for regional development at various levels of activity. This paper has its roots in a belief that the more complex situations are, the more regional development is dependent on the leadership and network management capacity of key individuals. Studying more deeply the roles that various individuals, and the coalitions formed by them, have in institutionalisation, deinstitutionalisation and reinstitutionalisation processes might provide us with additional analytical leverage in regional development studies. This paper focuses on diffuse networks of dispersed powers from a Finnish regional development officer’s point of view. Regional development officers are those people whose job it is to boost the economic development of their respective regions in Finland.The research questions discussed here are: (a) What kind of power is exercised by Finnish regional development officers; and (b) how do regional development officers aim to gain influence for their efforts to promote regional development? The empirical research is based on data gathered (a) through 41 interviews with Finnish actors responsible for the promotion of economic development in city governments, technology centres, regional development agencies, and ministries and other national bodies, and (b) through internet survey of development officers at local, regional and national levels (531 respondents, response rate 51.8%). The survey was designed to solicit information about power and influence tactics in the context of regional development. The empirical analysis shows, for example, how interpretive power and network power are more important for regional development officers than institutional and resource power, and how indirect influence tactics surpass direct tactics.     

Size-resolved characteristics of inorganic ionic species in atmospheric aerosols at a regional background site on the South African Highveld

Aerosols consist of organic and inorganic species, and the composition and concentration of these species depends on their sources, chemical transformation and sinks. In this study an assessment of major inorganic ions determined in three aerosol particle size ranges collected for 1 year at Welgegund in South Africa was conducted. SO₄^2? and ammonium (NH₄⁺) dominated the PM₁ size fraction, while SO₄^2? and nitrate (NO₃) dominated the PM_1–2.5 and PM_2.5–10 size fractions. SO₄^2? had the highest contribution in the two smaller size fractions, while NO₃^? had the highest contribution in the PM_2.5–10 size fraction. SO₄^2? and NO₃^? levels were attributed to the impacts of aged air masses passing over major anthropogenic source regions. Comparison of inorganic ion concentrations to levels thereof within a source region influencing Welgegund, indicated higher levels of most species within the source region. However, the comparative ratio of SO₄^2? was significantly lower due to SO₄^2? being formed distant from SO₂ emissions and submicron SO₄^2? having longer atmospheric residencies. The PM at Welgegund was determined to be acidic, mainly due to high concentrations of SO₄^2?. PM₁ and PM_1–2.5 fractions revealed a seasonal pattern, with higher inorganic ion concentrations measured from May to September. Higher concentrations were attributed to decreased wet removal, more pronounced inversion layers trapping pollutants, and increases in household combustion and wild fires during winter. Back trajectory analysis also revealed higher concentrations of inorganic ionic species corresponding to air mass movements over anthropogenic source regions.