PM10 AND PM2.5 AEROSOL FRACTIONS IN ZAGREB AIR

K. ŠEGA, J. HRŠAK, M. ČAČKOVIĆ and I. BEŠLIĆ

Institute for Medical Research and Occupational Health

10001 Zagreb, P. Box 291, Croatia

Keywords: metals, chlorides, nitrates, sulphates

INTRODUCTION

Since concentrations of PM10, PM2.5 and their constituents, show much higher correlation to the negative health effects compared to the total suspended particulate matter, their monitoring turned to be indispensable and routine procedure in developed countries. For this reason started the construction and assessment of the equipment, which will due to its characteristics and price fulfil the needs of particulate monitoring in Croatia. This paper presents the pilot study results of sulphate, nitrate and chloride, as well as lead, manganese and cadmium content in PM10 and PM2.5 particle fractions in Zagreb air.

METHODS

Daily samples were collected each day during year 1999 at one sampling site situated in the residential part of the town with a moderate to high traffic density. Fine particle fractions were collected on membrane filters (Millipore SSWP09025; AAWP09025; pore size 0.8 m). Air inlets are designed in the way to minimize the influence of wind (up to 14 km h-1) and mist (Liu and Pui, 1981; Agarwal and Liu, 1980), while both particle fractions are separated by means of inertial impactors with optimal characteristics concerning Stokes (Stk 0.226), Reynolds number (Re 3000) and jet to plate distance/jet diameter ratio ≥1.5 (Marple and Willeke, 1976). Air flow through the sampler of 1.17 10-3 m3s-1 provides sufficient mass of the sample from approximately 100 m3 of air for further chemical analysis of the samples.

RESULTS

Pollutant	N	Median ( gm-3)	g
PM10	356	35.9	2.04
PM2.5	357	28.5	2.23
Pb10	363	0.100	2.14
Pb2.5	363	0.095	2.01
Mn10	363	0.0049	2.10
Mn2.5	363	0.0029	2.08
Cd10	363	0.00067	1.74
Cd2.5	363	0.00059	1.77
Cl10	360	0.262	2.92
Cl2.5	363	0.259	2.69
NO310	360	2.47	2.42
NO32.5	363	2.03	2.75
SO410	360	4.48	2.15
SO42.5	363	4.33	2.11

Table 1. Number of samples, medians and geometric standard deviations

Mass concentrations of PM10 and PM2.5 fractions were determined using gravimetric method (5). Mass concentrations of water soluble chloride, nitrate and sulphate content, in both particle fractions, were determined by ion chromatography (Weiss, 1995), while the metal content was determined by atomic absorption spectrometry method (Christian and Feldman, 1970). The sample distributions of all pollutants could be approximated (p < 0.001) to log-normal distribution. Number of samples, medians and geometric standard deviations are shown in Table 1. Relationships between different components were investigated by means of factor analysis (Table 2)

Factor	Factor	Factor
1	2	3
PM10	0.4789	0.7883	0.1006
PM2.5	0.4981	0.7888	0.0976
Pb10	0.8748	0.2509	0.0646
Pb2.5	0.8548	0.2817	0.0454
Mn10	0.7748	0.2444	0.1035
Mn2.5	0.8100	0.3824	0.0866
Cd10	0.0871	0.0851	0.9396
Cd2.5	0.0528	0.1087	0.9393
Cl10	0.8650	0.0344	0.0245
Cl2.5	0.8209	0.0821	0.0141
NO310	0.5596	0.7039	0.1047
NO32.5	0.5657	0.6906	0.0962
SO410	0.0227	0.9448	0.0580
SO42.5	0.0351	0.9518	0.0690
5.2974	4.3899	1.8385
Prp.Totl	0.3784	0.3136	0.1313

Table 2. Factor loadings (Varimax normalized, Extraction: Principal components)

CONCLUSIONS

- PM2.5 and PM10 concentrations levels, as well as their ratio are in the typical range for urban residential areas. No significant difference between particle fractions considering metal and anion content is shown.

- It could be concluded that lead and manganese are probably present in air in the form of chlorides.

- Nitrates and sulphates contribute significantly to the overall particle mass.

- Cadmium in ambient air originate from the separate source, not related to other pollutants.

REFERENCES

Agarwal, J.K. and Liu, B.Y.H.: A Criterion for Accurate Aerosol Sampling in Calm Air. American Industrial Hygiene Association Journal, 41 (1980) 191-197.

Christian, G. D. and Feldman, F. J.: Atomic Absorption Spectroscopy, J.Wiley and Sons, London 1970.

Liu, B.Y.H. and PUI, D.Y.H.: Aerosol Sampling Inlets and Inhalable Particles. Atmospheric Environment 15 (1981) 589-600.

Marple, V.A. and Willeke, K.: Impactor Design. Atmos. Environ.10 (1976) 891-896.

Weiss J. Ion chromatography. 2nd ed. Weinheim, New York, Basel, Cambridge, Tokyo: VCH, 1995.