Narrow city streets surrounded by tall buildings are favorable to inducing a general effect of a “canyon” in which pollutants strongly accumulate in a relatively small area because of weak or ...inexistent ventilation. In this study, levels of nitrogen-oxide (NO2), elemental carbon (EC) and organic carbon (OC) mass concentrations in PM10 particles were determined to compare between seasons and different years. Daily samples were collected at one such street canyon location in the center of Zagreb in 2011, 2012 and 2013. By applying machine learning methods we showed seasonal and yearly variations of mass concentrations for carbon species in PM10 and NO2, as well as their covariations and relationships. Furthermore, we compared the predictive capabilities of five regressors (Lasso, Random Forest, AdaBoost, Support Vector Machine and Partials Least squares) with Lasso regression being the overall best performing algorithm. By showing the feature importance for each model, we revealed true predictors per target. These measurements and application of machine learning of pollutants were done for the first time at a street canyon site in the city of Zagreb, Croatia.
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•Applying Machine Learning Methods of traffic-related pollutants at a street canyon site, Croatia.•Selection of features and ability to explain model were improved with permutation importance.•The predictivity of pollutants by regression models increases in order PM10 < NO2 < EC < OC.•Test predictivity of pollutants are important for future urban planning and air quality.
Platinum (Pt), palladium (Pd) and rhodium (Rh) are most widely used in the production of automotive catalytic converters that serve to reduce toxic emissions from motor vehicles. The aim of this ...study was to quantitatively determine the levels of platinum, palladium and rhodium in the PM10 and PM2.5 fraction of airborne particle matter and find their spatial and temporal distribution at different polluted areas of the city of Zagreb, Croatia. The method used in this paper included weekly sampling of airborne particle matter on quartz filters, microwave digestion in acid under high pressure and temperature, and analysis by inductively coupled plasma mass spectrometry (ICP MS). The results have shown that the highest mean values at all three sampling stations (North, Center, South) were obtained for palladium (3.856 pg m−3, 5.396 pg m−3, 5.600 pg m−3) and the lowest for rhodium (0.444 pg m−3, 0.643 pg m−3, 0.750 pg m−3). The average mass concentrations of platinum group elements (PGE) in PM10 increased for all three elements in the direction North < Center < South which had to do with the traffic load nearby the monitoring stations. The ratio of measured mass concentrations to all measuring stations was similar to platinum, palladium and rhodium content in automotive catalytic converters. Factor analysis grouped platinum, palladium and rhodium at all of the monitoring stations, and their relation to other metals together with the aforementioned results indicate that their main source of pollution is traffic or precisely automotive catalytic converters. At all three of the monitoring sites, higher values were measured during the colder part of the year. The results of measuring platinum, palladium and rhodium levels in the city of Zagreb are the first results of their kind for this area and will provide insights into the contribution of catalytic converters to the presence of these elements in the environment.
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•First measurements of Pt, Pd and Rh in PM10 and PM2.5 in Croatia•Higher concentrations of PGE related to higher traffic density•Lower concentrations of PGE found in summer compared to winter•Ratios of PGE found in PM10 similar to the ratio in automotive catalytic converters
A measurement station located in an urban area on the southern slope of the Medvednica Mountain (120 m a.s.l.), close to the Croatian capital Zagreb, provided data for an analysis of the photosmog in ...the city of Zagreb. Data for the period 2003–2016 obtained from this station and analysed in this work can also be compared with the nearby Puntijarka station (980 m a.s.l.) for which a similar analysis has already been carried out. In Puntijarka station analysis, it has been shown that there is most probably no significant change in ozone concentrations during the observed period. In this study the mean value of the annual ozone volume fractions showed a linear trend of 0.23 ppb yr
−1
, a growth that is in the worst case scenario among the lowest global prediction, while the seasonal (April-to-September) mean values had a trend of 0.32 ppb yr
−1
, which is a certain clearly observable growth. The 95-percentile values had trends of 0.009 ppb yr
−1
(annual data) and −0.072 ppb yr
−1
(seasonal data), respectively. Both of these values show very small changes if any at all. By using FT analysis, with the calculation of uncertainties, we have observed three prominent cycles of 169 ± 4 h (weekly cycle), 24 ± 1 h and 12 ± 1 h (diurnal cycles). Uncertainties were low which strongly indicate that the cycles are present. However, since high concentrations of ozone were observed only sporadically, ozone pollution in the northern part of Zagreb is at the present rather low. A Fourier transformation was used to analyse the data for periodic behaviour, which revealed the existence of diurnal and weekly modulations. Nevertheless, constant monitoring is important and will continue in the future as part of continuous monitoring of the ozone levels in the area.
The aim of this study was to determine the influence of traffic density on air pollutant levels as well as to analyse the spatial and temporal distribution of particulate pollutants and their health ...risk. The following species related to traffic pollution were measured: PM
10
, elemental and organic carbon and polycyclic aromatic hydrocarbons (PAHs) in PM
10
and gas pollutants (SO
2
, NO
2
and CO). The measurements were carried out at four crossroad sites in the city. Samples of PM
10
were collected over three periods (6 am to 2 pm, 2 pm to 10 pm and 10 pm to 6 am) on working days and weekends. Statistically significant differences were found between sampling sites for all pollutant concentrations, except for NO
2
. The highest mass concentrations of PM
10
, carbon and PAHs were observed in the south of the city with the highest traffic density. Concentrations of gasses (CO and NO
2
) showed high values in morning and in the late afternoon and evening (west and east). At all measuring sites, the highest concentration of particle-bound pollutants was mostly recorded during morning and afternoon, except at the south, where elevated PAHs concentrations were recorded during night period, which indicated that residential heating takes up a portion of pollution sources in this area. Although for most of the pollutants the concentrations varied during the day, statistically significant differences between sampling periods were not found. The highest health risk was obtained at the south, where it was scored as significant.
The mass concentrations and content of water-soluble anions (Cl−, NO3−, SO42−) and cations (Na+, NH4+, K+, Mg2+, Ca2+) in the PM2.5 particle fraction were measured, and an investigation of their ...relationship and their contribution to the total PM2.5 mass measured was conducted at an urban background site as part of the Croatian monitoring network for air quality located in Rijeka, Croatia. Daily samples of PM2.5 particle fraction were collected over 2017 on PTFE filters using a low volume sampler Sven Leckel SEQ 47/50. Mass concentrations of the PM2.5 particle fraction were determined by gravimetry according to the standard HRN EN 12341:2014 (EN 12341:2014). The content of water-soluble inorganic anions and cations were determined using a Thermo Scientific ICS-5000 capillary ion chromatograph. Results show that the annual average PM2.5 mass concentration was 9.65 μg m-3 and did not exceed the limit value of 25 μg m-3 given by the Regulation on the level of pollutants in air (OG No. 117/12). The annual average mass concentrations of ions in PM2.5 particle fraction was SO42−> NH4+> NO3− > Ca2+> K+> Na+> Cl− > Mg2+. The contributions of total anion mass and total cation mass to the total PM2.5 mass were 25.4% and 12.8%, respectively. The acidic property of PM2.5 was obtained in spring and winter and slightly acidic in summer and autumn. For a prediction of the pollutant sources, we ran a factor analysis which was performed using the statistical packages STATISTICA 13.0. After varimax rotation, the obtained four principal component factors were found to account for 86% of the variance. Factor loadings > 0.7 were considered significant.
•The annual average mass concentrations of PM2.5 did not exceed the limit value.•The average ion mass concentrations was SO42− > NH4+> NO3− > Ca2+> K+> Na+> Cl− > Mg2+.•The most contributing ions to the total PM2.5 mass were SO42−, NH4+ and NO3−•Strong correlation indicated presence secondary aerosols (NH4)2SO4, NH4HSO4, NH4NO3.•Results implies acidic property of PM2.5
The reliability of the measurement method in determining the mass concentration of wood dust relates to the sampling time for the detection of wood particles in the ambient air of woodworking places. ...The aim of this study was to calculate the mass limit of detection (LOD), limit of quantification (LOQ), and the minimal sampling time (tLOD and tLOQ) for determination and quantification of samples, based on the hardwood dust mass concentration at various woodworking places in the sawmills, floor production factories, and carpentries. Determination of the mass concentration of respirable, inhalable, and total hardwood dust from ambient air was performed using personal sampling pumps and three types of filter holders: respirable dust cyclone, Institute of Occupational Medicine IOM inhalable dust sampler, and total dust open-faced filter holder. The average limit of detection amounts to 0.052, 0.083, and 0.167 mg for respirable, inhalable, and total hardwood dust, respectively. The minimal detection sampling time for collecting all observed types of dust fractions ranged between 1.12 h and 1.72 h. The minimal quantification time for all collected hardwood dust samples ranged from 3.75 h to 5.51 h. Pearson’s correlation test showed that the reliability of the measurements was affected more by the dustiness of the workspace than the real sampling time.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Concentrations of ten polycyclic aromatic hydrocarbons (PAHs) in the PM10 particle fraction were measured together with ozone and meteorological parameters at an urban site (Zagreb, Croatia) over a ...one-year period. Data were subjected to regression analysis in order to determine the relationship between the measured pollutants and selected meteorological variables. All of the PAHs showed seasonal variations with high concentrations in winter and autumn and very low concentrations during summer and spring. All of the ten PAHs concentrations also correlated well with each other. A statistically significant negative correlation was found between the concentrations of PAHs and ozone concentrations and concentrations of PAHs and temperature, as well as a positive correlation between concentrations of PAHs and PM10 mass concentration and relative humidity. Multiple regression analysis showed that concentrations of PM10 and ozone, temperature, relative humidity and pressure accounted for 43–70% of PAHs variability. Concentrations of PM10 and temperature were significant variables for all of the measured PAH's concentrations in all seasons. Ozone concentrations were significant for only some of the PAHs, particularly 6-ring PAHs.
Polycyclic aromatic hydrocarbons (PAHs) originate from a variety of natural and industrial processes. In this paper, concentrations of nine PAHs in PM
10
particle fraction were measured concurrently ...at four different sites (rural, urban residential, urban traffic, and residential-industrial) in continental Croatia. Measurements at all of the four sites showed much higher average concentrations for all of the PAHs in the winter period. The highest winter average values were measured at the industrial site and the lowest at the rural and the urban residential site. In the summer, the highest average values were also measured in the industrial area, except for benzo(ghi)perylene and indeno(1,2,3-cd)pyrene, which showed the highest average values in the rural area. Factor analysis has been applied to PAH concentrations to identify their potential sources. Extracted factors have been interpreted on basis of previous studies and weather conditions. The diagnostic ratios calculated in this study indicated mixed sources at all of the sites. The contribution of gasoline and diesel from traffic was significant at all of the sites except for the urban industrial. In the winter, potential PAH sources also arose from wood combustion. The industrial site differed from the other sites with the highest influence of diesel sources and refinery during the summer months. The contribution of BaP in total carcinogenic activity exceeded 50 % in both seasons at all of the measured sites, which suggests that BaP could be suitable as a marker of the carcinogenic potential of a PAH mixture.
Praćenje razina koncentracija PM2,5 frakcije lebdećih čestica kao i određivanje njihova kemijskog sastava od velike je važnosti s obzirom na to da su brojna istraživanja pokazala povezanost te ...frakcije čestica i štetnih učinaka na zdravlje ljudi i kvalitetu okoliša. Na mjernoj postaji smještenoj na području Nacionalnog parka Plitvička jezera sakupljani su 24-satni uzorci frakcije lebdećih čestica PM2,5 na filtrima od kvarcnih vlakana tijekom 2015. godine. Masene koncentracije frakcije lebdećih čestica PM2,5 gravimetrijski su određene, dok su masene koncentracije organskog (OC) i elementnog (EC) ugljika određene metodom termičko-optičke transmisije. Najviše masene koncentracije lebdećih čestica, OC-a i EC-a izmjerene su ljeti, dok su najniže izmjerene zimi.
Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna .
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