Συμβολή στη διερεύνηση της ατμοσφαιρικής ρύπανσης σε αστική και βιομηχανική περιοχή με χημικές και υπολογιστικές μεθόδους

Abstract

Several epidemiological studies have shown an association between particulate air pollution and health effects. Suspended particulates and more, specifically, the inhalable PM₁₀ fraction appears to cause respiratory health effects and heart diseases. Moreover, the penetration of particles into respiratory track is a function of the size of the particles and thus, it is more likely for the finer PM₂․₅ fraction to reach the deepest of the lugs. Particulate pollution is of paramount importance in areas with open-pit mines because of its human health related effects. The phenomenon becomes worse when it is combined with raw lignite transfer and combustion in power stations (PS) through the resuspension of particles and stack emissions, respectively. Kozani-Ptolemais Basin (KPB) is a heavy industrialized area in the northwestern part of Greece, which is characterized by complex topography. Within the basin, lignite PS operates with a total installed generating capacity of more than 4.7 GW. These PS contribute to about 57% of the total electrical energy produced in Greece. The lignite used by these power stations is mined in the nearby open-pit mines. Dust emissions seem to be the most serious problem in the area, as the measured ambient concentrations of suspended particles are at high levels and exceed local and international standards. Various studies have been published regarding the atmospheric pollution of the wider KPB region so that is appreciated the quality of air and are investigated the mechanisms of dissemination and transport of pollutants. Whilst fewer studies concerned the chemical constitution of total suspended particles. Therefore, it is very well commented in the literature of the high concentrations of suspended particles and their air quality problems in the region. But up to now, there were no estimations of chemical composition of ΡΜ₁₀ and PM₂․₅ in the region. The objective of the present thesis is the study of ΡΜ₁₀ and PM₂․₅ chemical composition in a neighbouring urban and industrial region. It is also attempted estimation of concentrations of toxic substances that is found in the suspended particles in relation to the contribution of anthropogenic activities in their concentrations. Size-segregated particulate samples (ΡΜ₁₀ and PM₂․₅) were collected in the industrial area next to the opencast mines at the village of Klitos and the urban area of Kozani in north-western Greece, for a period of one year. For the completion of the study there were developed while improved techniques of analysis of suspended particles. Their analysis included morphological characterization of particles by the use of scanning electron microscopy (SEM), determination of concentrations of trace elements with X-Ray fluorescence spectroscopy (ED-XRF), determination of concentrations of particles associated polychlorinated biphenyls (PCBs) and polynuclear aromatic hydrocarbons (PAHs) by gas chromatography and the measurement of toxicity to aquatic micro organisms of ΡΜ₁₀ and PM₂․₅. Low volume samplers have been used for trapping suspended particles. The filters used were teflo, which are ideal for analysis of trace elements with X-Ray fluorescence spectroscopy, while they are ideal for storage in the determination of PAHs and PCBs. The determination of PAHs and PCBs has been carried out by the use of the analytic technique of large volume injection and gas chromatography-mass spectrometry (LVI-GC/MS) together with an analytic technique that was developed in the present thesis. The combined method that has been developed can be used when it is required high sensitivity, as in the case where low volume samplers are used. The extraction of substances has been made by the combination of agitation with reflux solvent and bath of ultrasounds with reflux solvent. This technique gave high recoveries of PAHs and PCBs, in short time intervals. The method’s detection limits were 0.025-0.333 ngmlˉ¹ and considering 24 hours sampling with constant flow 16.67 lminˉ¹ the limits were 0.03-0.014 ngmˉ³. The determination of 29 trace elements has been carried out by X-Ray fluorescence spectroscopy, by a method that was developed in the present thesis. The method is based on reference curves from handmade standards prepared in the laboratory, dripping solution of trace elements on teflo filters. The method’s detection limits were 0.1-14.7 ngmˉ³. The morphological characterization of suspended particles resulted to an important rate of fly ash on the filters. In Kozani, higher rate of sulphur than at Kleitos was found, which was attributed in the combustion of lignite or/and oil. The smaller rate ofsulphur at Kleitos was due to the higher percentage of other elements (Ca, Si, Al, Fe and Mg) because of the mining activities and also due to the resuspension of road dust that contains significant amounts of fly ash. The determination of concentrations of trace elements showed higher rates for all the elements in Kleitos than in Kozani. The study of diagnostic ratios of the elemental concentrations in the PM, it appeared that the mining operations and the combustion of coal constituted the basic source of heavy metals in the region. The collections of elements in the two places presented the same fluctuation indicating common sources. These heavy metals’ sources were determined by the use of multivariate statistical analysis. The recognised sources were combustion of oil and lignite, dust of mines with fly ash, the exhaust of cars, the secondary particulates and wood combustion. The concentrations of 16 PAHs, in PM₂․₅ and PM₁₀ were also studied. It was found that high molecular weight PAHs had higher concentrations in Kozani showing traffic contribution while lower molecular weight PAHs had high concentrations in Kleitos which were attributed in the combustion of coal. The concentrations during the cold period (October-April), were higher than during the hot period (April-October) because of their rapid destruction and the higher gas phase fraction. PAHs’ concentrations in Kleitos during the cold period were higher than those of Kozani, whilst in certain cases almost double. On the contrary during the hot period the concentrations for the high molecular PAHs were higher in Kozani. This was possibly due to the emissions of cars that are closer at the sampling site in antithesis with Kleitos. Compared to other studies in different urban places in the world the concentrations that were calculated in the present thesis were relatively lower or at the same levels. It was also found a very good correlation of PAHs’ concentrations between the two locations showing common sources effects and local meteorological conditions influence. Sources of PAHs have been studied by seasonal sampling in relation to diagnostic ratios and multivariate statistical analysis. The sources that have been recognized were rated by the use of the response model APCA (Absolute Principal Component Analysis). According to this, for Kozani the coal combustion contributed 40% in the concentrations of PAHs in PM₂․₅ and PM₂․₅₋₁₀ and the cars 54%, respectively. In Kleitos, contributed 63% the coal combustion and the cars 35% in the concentrations of PAHs in PM₂․₅. For PM₁₀ traffic contributed in percentage of 51% and the coal with the diesel cars in percentage of 54%. Generally speaking, the coal contributes in higher rates to the concentrations of small molecular weight PAHs while the oil combustion and cars contribute in higher percentage in the concentrations of greater molecular weight PAHs. For the concentrations of PCBs that are bound in the suspended particles it was found that in Kleitos they are lower than those of Kozani with the exception of the hot period, while high concentrations have been observed during the cold period at both locations. From the PCBs correlation with other pollutants and with meteorological parameters appeared that their sources are mostly local, while important was the effect of cars. Finally, the ecotoxicological effects of PM₂․₅ and PM₁₀ particulates was determined by Vibrio fischeri and bioassays. Five consecutive dilutions of many samples were tested in order to determine the EC₅₀ values (the % of sample concentration that causes 50% effect on the test organism) of each sample. Generally, PM₂․₅ presented higher toxicity than PM₁₀. In addition, the suspended particles appeared more toxic in the bacterium vibrio fischeri in Kleitos than those in Kozani. PAHs’ samples testing has shown that toxicity increases with PAHs concentration. The total toxicity of particles however was significantly higher, proving the influence of other substances in the total toxicity needing more future investigation.

[…] Θέμα της παρούσας διατριβής είναι η μελέτη της σύστασης σωματιδίων με διάμετρο μικρότερη των 10μm (ΡΜ₁₀) στην ατμόσφαιρα αστικών και βιομηχανικών περιοχών. Στόχος της μελέτης αυτής είναι να γίνει ορθή και ακριβής εκτίμηση των συγκεντρώσεων των ενώσεων που βρίσκονται στα αιωρούμενα σωματίδια (ΡΜ) και ταυτόχρονα να αποτυπωθεί η συνεισφορά των ανθρωπογενών δραστηριοτήτων στις εκπομπές των ενώσεων αυτών. Οι επιμέρους στόχοι της παρούσας διατριβής μπορούν να οριοθετηθούν ως εξής: 1) Βελτίωση και ανάπτυξη κατάλληλης δειγματοληπτικής και αναλυτικής μεθοδολογίας για τον προσδιορισμό των βαρέων μετάλλων. 2) Βελτίωση και ανάπτυξη κατάλληλης αναλυτικής μεθοδολογίας για τον προσδιορισμό ανθεκτικών οργανικών ρυπαντών (Persistent Organic Pollutants ή POPs) συμπεριλαμβανομένων των πολυκυκλικών αρωματικών υδρογονανθράκων (PAHs) και των πολυχλωριωμένων διφαινυλίων, που βρίσκονται προσροφημένοι στα αιωρούμενα σωματίδια με διάμετρο <10μm (PM₁₀) ή και 2.5μm (PM₂․₅). 3) Μελέτη της εποχιακής διακύμανσης των βαρέων μετάλλων και των POPs σε αστική περιοχή και βιομηχανική περιοχή. 4) Χρήση διαγνωστικών κριτηρίων για την ταυτοποίηση των πηγών των ρυπαντών. 5) Εφαρμογή μοντέλου αποδέκτη για την ταυτοποίηση των πηγών των ρυπαντών και ποσοτικοποίηση της συνεισφοράς τους. 6) Εκτίμηση της συνολικής τοξικότητας των αιωρουμένων σωματιδίων. Οι βασικοί άξονες που καθορίζουν τη δομή της εργασίας είναι: Βιβλιογραφική επισκόπηση των μελετών που έχουν πραγματοποιηθεί σχετικά με τη μέθοδο ανάλυσης της χημικής σύστασης των ΡΜ και τα αποτελέσματά της ανάλυσής τους. Βιβλιογραφική επισκόπηση των κριτηρίων για τον προσδιορισμό των πηγών καθώς και των μοντέλων ταυτοποίησης και ποσοτικοποίησης της συνεισφοράς των πηγών στις συγκεντρώσεις των επικίνδυνων για την ανθρώπινη υγεία ρυπαντών. Μεθοδολογία που βελτιώθηκε ή και αναπτύχθηκε για τον προσδιορισμό της χημικής σύστασης των ΡΜ. Επεξεργασία-συζήτηση των αποτελεσμάτων ανάλυσης της σύστασης των αιωρουμένων σωματιδίων. […]