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Kauhaniemi M.,Finnish Meteorological Institute | Kukkonen J.,Finnish Meteorological Institute | Harkonen J.,Finnish Meteorological Institute | Nikmo J.,Finnish Meteorological Institute | And 6 more authors.
Atmospheric Environment | Year: 2011

We have slightly refined, evaluated and tested a mathematical model for predicting the vehicular suspension emissions of PM10. The model describes particulate matter generated by the wear of road pavement, traction sand, and the processes that control the suspension of road dust particles into the air. However, the model does not address the emissions from the wear of vehicle components. The performance of this suspension emission model has been evaluated in combination with the street canyon dispersion model OSPM. We used data from a measurement campaign that was conducted in the street canyon Runeberg Street in Helsinki from 8 January to 2 May, 2004. The model reproduced fairly well the seasonal variation of the PM10 concentrations, also during the time periods, when studded tyres and anti-skid treatments were commonly in use. For instance, the index of agreement (IA) was 0.83 for the time series of the hourly predicted and observed concentrations of PM10. The predictions of the model were found to be sensitive to precipitation and street traction sanding. The main uncertainties in the predictions are probably caused by (i) the cleaning processes of the streets, which are currently not included in the model, (ii) the uncertainties in the estimation of the sanding days, and (iii) the uncertainties in the evaluation of precipitation. This study provides more confidence that this model could potentially be a valuable tool of assessment to evaluate and forecast the suspension PM10 emissions worldwide. However, a further evaluation of the model is needed against other datasets in various vehicle fleet, speed and climatic conditions. © 2011 Elsevier Ltd.


Pirjola L.,Helsinki Metropolia University of Applied Sciences | Pirjola L.,University of Helsinki | Lahde T.,Helsinki Metropolia University of Applied Sciences | Niemi J.V.,Helsinki Region Environmental Services Authority HSY | And 7 more authors.
Atmospheric Environment | Year: 2012

A measurement campaign by a mobile laboratory van was performed in urban microenvironments bounded by a busy street Mannerheimintie in the city center of Helsinki, Finland. The characteristics of spatiotemporally high-resolution pollutant concentrations were studied such as ultrafine particles in the size range of 3-414 nm, black carbon BC, fine particle mass PM 2.5, as well as nitrogen oxides NO and NO 2. In addition, the effects of street geometry and roadside structure on the local dispersion of traffic emissions were analyzed as well. Meteorological conditions stayed stable and the wind direction was perpendicular to Mannerheimintie during the campaign. The highest particle concentrations were ∼8 × 10 5 cm -3, of which around 94% was smaller than 40 nm. At the pavement, the average concentration was in maximum 5 × 10 4 cm -3; around 80% of the particles was smaller than 40 nm. The volatility fraction was 75% by number. Due to the street canyon effect by the surrounding buildings, the downwind concentrations were around 24% of the upwind concentrations for particle number, 28% of NO, 39% of BC and 70% of NO 2 concentrations. Furthermore, the upwind concentrations were higher than the simultaneously measured concentrations within the traffic flow. In fact, the particle count was around 3-fold, BC 2.5-fold, PM 2.5 and NO 2 1.5-fold compared to the concentrations while driving. Thus, for this measurement site and under these meteorological conditions, the exposure to pedestrians and cyclist on the upwind pavement is even higher than the driver's exposure. If the downwind buildings were parallel to Mannerheimintie, the concentrations dropped significantly at the pavement and continued decreasing slightly in the courtyards. When the downwind buildings were perpendicular to Mannerheimintie, a gradual reduction in the concentrations between the buildings was observed. However, at a distance of approximately a hundred meters a parallel side street which was a street canyon, started to affect the concentrations resulting in an increased exposure risk for pedestrians and cyclists. Understanding the local transport and the dispersion of traffic emissions are important for city planning and air quality assessment. © 2012 Elsevier Ltd.


Heinonen M.,Helsinki Region Environmental Services Authority HSY | Jokelainen M.,Helsinki Region Environmental Services Authority HSY | Fred T.,Helsinki Region Environmental Services Authority HSY | Koistinen J.,Finnish Meteorological Institute | Hohti H.,Finnish Meteorological Institute
Water Science and Technology | Year: 2013

Municipal wastewater treatment plant (WWTP) influent is typically dependent on diurnal variation of urban production of liquid waste, infiltration of stormwater runoff and groundwater infiltration. During wet weather conditions the infiltration phenomenon typically increases the risk of overflows in the sewer system as well as the risk of having to bypass the WWTP. Combined sewer infrastructure multiplies the role of rainwater runoff in the total influent. Due to climate change, rain intensity and magnitude is tending to rise as well, which can already be observed in the normal operation of WWTPs. Bypass control can be improved if the WWTP is prepared for the increase of influent, especially if there is some storage capacity prior to the treatment plant. One option for this bypass control is utilisation of on-line weather-radar-based forecast data of rainfall as an input for the on-line influent model. This paper reports the Viikinmäki WWTP wet weather influent modelling project results where gridded exceedance probabilities of hourly rainfall accumulations for the next 3 h from the Finnish Meteorological Institute are utilised as on-line input data for the influent model. © IWA Publishing 2013.


Pirjola L.,Helsinki Metropolia University of Applied Sciences | Pirjola L.,University of Helsinki | Pajunoja A.,Tampere University of Technology | Pajunoja A.,University of Eastern Finland | And 5 more authors.
Atmospheric Measurement Techniques | Year: 2014

Four measurement campaigns were performed in two different environments - inside the harbour areas in the city centre of Helsinki, and along the narrow shipping channel near the city of Turku, Finland - using a mobile laboratory van during winter and summer conditions in 2010-2011. The characteristics of gaseous (CO, CO2, SO2, NO, NO2, NOx) and particulate (number and volume size distributions as well as PM2.5) emissions for 11 ships regularly operating on the Baltic Sea were studied to determine the emission parameters. The highest particle concentrations were 1.5 × 106 and 1.6 × 105 cm-3 in Helsinki and Turku, respectively, and the particle number size distributions had two modes. The dominating mode peaked at 20-30 nm, and the accumulation mode at 80-100 nm. The majority of the particle mass was volatile, since after heating the sample to 265 C, the particle volume of the studied ship decreased by around 70%. The emission factors for NOx varied in the range of 25-100 g (kg fuel)-1, for SO2 in the range of 2.5-17.0 g (kg fuel)-1, for particle number in the range of (0.32-2.26) × 1016 # (kg fuel)-1, and for PM2.5 between 1.0-4.9 g (kg fuel)-1. The ships equipped with SCR (selective catalytic reduction) had the lowest NOx emissions, whereas the ships with DWI (direct water injection) and HAMs (humid air motors) had the lowest SO2 emissions but the highest particulate emissions. For all ships, the averaged fuel sulphur contents (FSCs) were less than 1% (by mass) but none of them was below 0.1% which will be the new EU directive starting 1 January 2015 in the SOx emission control areas; this indicates that ships operating on the Baltic Sea will face large challenges. © Author(s) 2014.


Dos Santos-Juusela V.,University of Helsinki | Petaja T.,University of Helsinki | Kousa A.,Helsinki Region Environmental Services Authority HSY | Hameri K.,University of Helsinki | Hameri K.,Finnish Institute of Occupational Health
Atmospheric Environment | Year: 2013

To estimate spatial-temporal variations of ultrafine particles (UFP) in Helsinki, we measured particle total number concentrations (PNC) continuously in a busy street and an urban background site for six months, using condensation particle counters (CPC). We also evaluated the effects of temperature, wind speed and wind direction on PNC, as well as the correlation between PNC and PM2.5, PM10 and black carbon (BC) at the street. We found that on weekdays, hourly median PNC were highly correlated with BC (r=0.88), moderately correlated with PM2.5 (r=0.59) and weakly correlated with PM10 (r=0.22). Number concentrations at the street were inversely proportional to temperature and wind speed, and highly dependent on wind direction. The highest PNC occurred during northeastern winds while the lowest occurred during southwestern winds. As these wind directions are nearly perpendicular to the street axis, the formation of wind vortices may have influenced the dispersion of UFP in the site. Although the temporal correlation for PNC was moderately high between the sites (r=0.71), the median concentration at the street was 3 times higher than the urban background levels. The results indicate that people living or passing by the busy street are exposed to UFP concentrations well above the urban background levels. Thus, the study suggests that urban microenvironments should be considered in epidemiological studies. In addition the results emphasize that regulations based solely on PM2.5 and PM10 concentrations may be insufficient for preventing the adverse health effects of airborne particles. © 2013 Elsevier Ltd.


Saarnio K.,Finnish Meteorological Institute | Frey A.,Finnish Meteorological Institute | Niemi J.V.,Helsinki Region Environmental Services Authority HSY | Niemi J.V.,University of Helsinki | And 10 more authors.
Journal of Aerosol Science | Year: 2014

Globally more than a quarter of the total primary energy supply is based on coal combustion. The emissions of coal-fired power plants (CFPPs) are regulated in many industrialized countries and therefore power plants use cleaning techniques to minimize emissions such as sulfur dioxide (SO2) and particles. In this study, the particulate emissions from coal combustion were investigated at a CFPP (506MW) used for combined heat and power production in Helsinki, Finland. Fine particle samples (PM1) were collected after electrostatic precipitator before the desulfurization plant (DSP), including flue gas desulfurization unit (FGD) and baghouse filters, and simultaneously in the smokestack to study the influence of DSP to particulate mass and chemistry. The DSP removed over 97% of particle mass in flue gas. Trace metals were removed efficiently but contribution of some ionic compounds increased in the FGD process. The particle properties were studied in more detail in the smokestack including particle size distribution measurements and size-segregating sampling to study chemical composition and morphology of particles. The particulate emissions from the CFPP were relatively small, consisting mainly of products and reagents of the FGD process (e.g., CaSO4, NaCl) and partly of the primary emissions from the coal combustion (e.g., mineral ash and reaction products of gas phase components). The maximum in particle volume was detected at 0.68μm. PM1 contributed on average 62 ± 5% to PM10 mass. Besides particulate matter, also the gas-phase emission of mercury was studied because coal combustion is one of the major sources of mercury found in the environment. The mercury emissions were within the proposed limits in the EU. © 2014 Elsevier Ltd.


Kerminen V.-M.,Finnish Meteorological Institute | Kerminen V.-M.,University of Helsinki | Niemi J.V.,Helsinki Region Environmental Services Authority HSY | Niemi J.V.,University of Helsinki | And 12 more authors.
Atmospheric Chemistry and Physics | Year: 2011

The volcanic eruption of Grimsvötn in Iceland in May 2011 affected surface-layer air quality at several locations in Northern Europe. In Helsinki, Finland, the main pollution episode lasted for more than 8 h around the noon of 25 May. We characterized this episode by relying on detailed physical, chemical and optical aerosol measurements. The analysis was aided by air mass trajectory calculations, satellite measurements, and dispersion model simulations. During the episode, volcanic ash particles were present at sizes from less than 0.5 μm up to sizes >10 μm. The mass mean diameter of ash particles was a few μm in the Helsinki area, and the ash enhanced PM10 mass concentrations up to several tens of μg m -3. Individual particle analysis showed that some ash particles appeared almost non-reacted during the atmospheric transportation, while most of them were mixed with sea salt or other type of particulate matter. Also sulfate of volcanic origin appeared to have been transported to our measurement site, but its contribution to the aerosol mass was minor due the separation of ash-particle and sulfur dioxide plumes shortly after the eruption. The volcanic material had very little effect on PM 1 mass concentrations or sub-micron particle number size distributions in the Helsinki area. The aerosol scattering coefficient was increased and visibility was slightly decreased during the episode, but in general changes in aerosol optical properties due to volcanic aerosols seem to be difficult to be distinguished from those induced by other pollutants present in a continental boundary layer. The case investigated here demonstrates clearly the power of combining surface aerosol measurements, dispersion model simulations and satellite measurements in analyzing surface air pollution episodes caused by volcanic eruptions. None of these three approaches alone would be sufficient to forecast, or even to unambiguously identify, such episodes. © 2011 Author(s).


PubMed | Helsinki Region Environmental Services Authority HSY, City of Helsinki Environment Center, Finnish Environment Institute and Aalto University
Type: Journal Article | Journal: Water science and technology : a journal of the International Association on Water Pollution Research | Year: 2015

This study on the removal of microplastics during different wastewater treatment unit processes was carried out at Viikinmki wastewater treatment plant (WWTP). The amount of microplastics in the influent was high, but it decreased significantly during the treatment process. The major part of the fibres were removed already in primary sedimentation whereas synthetic particles settled mostly in secondary sedimentation. Biological filtration further improved the removal. A proportion of the microplastic load also passed the treatment and was found in the effluent, entering the receiving water body. After the treatment process, an average of 4.9 (1.4) fibres and 8.6 (2.5) particles were found per litre of wastewater. The total textile fibre concentration in the samples collected from the surface waters in the Helsinki archipelago varied between 0.01 and 0.65 fibres per litre, while the synthetic particle concentration varied between 0.5 and 9.4 particles per litre. The average fibre concentration was 25 times higher and the particle concentration was three times higher in the effluent compared to the receiving body of water. This indicates that WWTPs may operate as a route for microplastics entering the sea.


PubMed | Helsinki Region Environmental Services Authority HSY, Salon Vesi, Tampere University of Technology, University of Helsinki and University of Jyväskylä
Type: Journal Article | Journal: Journal of industrial microbiology & biotechnology | Year: 2016

Molecular monitoring of bacterial communities can explain and predict the stability of bioprocesses in varying physicochemical conditions. To study methanol-fed denitrification biofilters of municipal wastewater treatment plants, bacterial communities of two full-scale biofilters were compared through fingerprinting and sequencing of the 16S rRNA genes. Additionally, 16S rRNA gene fingerprinting was used for 10-week temporal monitoring of the bacterial community in one of the biofilters. Combining the data with previous study results, the family Methylophilaceae and genus Hyphomicrobium were determined as suitable target groups for monitoring. An increase in the relative abundance of Hyphomicrobium-related biomarkers occurred simultaneously with increases in water flow, NO


PubMed | Helsinki Region Environmental Services Authority HSY, University of Eastern Finland, Finnish Environment Institute and Aalto University
Type: | Journal: Water research | Year: 2016

Wastewater treatment plants (WWTPs) can offer a solution to reduce the point source input of microlitter and microplastics into the environment. To evaluate the contributing processes for microlitter removal, the removal of microlitter from wastewater during different treatment steps of mechanical, chemical and biological treatment (activated sludge) and biologically active filter (BAF) in a large (population equivalent 800000) advanced WWTP was examined. Most of the microlitter was removed already during the pre-treatment and activated sludge treatment further decreased the microlitter concentration. The overall retention capacity of studied WWTP was over 99% and was achieved after secondary treatment. However, despite of the high removal performance, even an advanced WWTP may constitute a considerable source of microlitter and microplastics into the aquatic environment given the large volumes of effluent discharged constantly. The microlitter content of excess sludge, dried sludge and reject water were also examined. According to the balance analyses, approximately 20% of the microlitter removed from the process is recycled back with the reject water, whereas 80% of the microlitter is contained in the dried sludge. The study also looked at easy microlitter sampling protocol with automated composite samplers for possible future monitoring purposes.

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