Characteristics of Respirable Particulate Metals Emitted by a Beehive Firework Display in YanShuei Area of Southern Taiwan

This study investigates metals in the PM1.0 and PM2.5 collected using a micro-orifice uniform deposition impactor (MOUDI) sampler in the YanShuei area of southern Taiwan during a beehive firework display. The results of sample analyses indicate that during the beehive firework display, the ratios of metal concentrations in PM2.5 (D) to the background level (B) at leeward sampling site were 1,828 for Ba, 702 for K, 534 for Sr, 473 for Cu, 104 for Mg, 121 for Al, and 98 for Pb. The corresponding data for PM1.0 were 3036, 838, 550, 676, 594, 190, and 126, respectively. According to the results of metal composition ratio, Principal Component Analysis (PCA), and upper continental crust (UCC) analyses, the concentrations of particle-bound Al, Ba, Cu, K, Mg, Pb, and Sr increased during the beehive firework displays, suggesting that firework-display aerosols contained abundant metal elements of Al, Ba, Cu, K, Mg, Pb, and Sr. Before (background), trial, during, and after the beehive firework display, the Ba, K, Cu, Mg, Pb, and Sr (commonly regarded as firework display indicator elements) accounted for 0.520, 2.45, 26.4 and 0.849% mass of PM1, respectively, while for PM2.5 the corresponding data were 0.777, 2.32, 23.8, and 0.776%, respectively.


INTRODUCTION
The short-term effects of air pollution on health have attracted increasing attention in recent years.The extensive use of pyrotechnics in large celebratory events frequently degrades short-term air quality significantly, possibly harming human health (causing chronic lung diseases, cancer, neurological and haematological diseases, for example) (Smith and Dinh, 1975;Clark, 1997;Godri et al., 2010;Moreno et al., 2010;Caballero, et al., 2015;Robles, et al., 2015).Fire work displays are known to increase ambient fine particle concentrations and fine-particulate metals (Vecchi et al., 2008;Lancaster et al., 1998;Perry, 1999;Kumara et al., 2016).The complex nature of the particles that are emitted during fireworks may have adverse health, effects as reported by Ravindra et al. (2001).Furthermore, in the 2007 Montréal International Fireworks Competition, PM 2.5 levels of 10,000 µg m -3 were reached, equal to approximately roughly 1,000 times the background level (Alexandre et al., 2010).Zhang et al. (2010) reported the measurement of the number concentrations and size distributions of aerosol particles with aerodynamic diameters in the range of 10 nm to 10 µm during the Chinese New Year's firework event in Shanghai, China.Particle concentrations during the peak hour of firework celebrations were approximately three times higher than on the preceding day, with a clear shift in the particles from nuclei mode (10-20 nm) and Aitken mode (20-100 nm) to accumulation mode (0.5-1.0 µm).
More than 10 million firecracker/firework rockets displayed in the Lantern festival night every year in the YanShuei area.Therefore, the firecracker/firework display emitted abundant PM 2.5 at the short-term.However, the mass concentrations and chemical compositions (metal components/concentrations) of PM 1.0 , PM 2.5 , and PM 10 from beehive firework displays have seldom been investigated.Accordingly, this study investigates the mass concentrations in PM 1.0 , PM 2.5 , and PM 10 , as well as the metal components (Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sr, and Zn) and concentrations in particles that were collected in the YanShuei area of southern Taiwan.The size distributions and cumulative mass fractions of metals in particles in each size range are obtained from the samples that were collected using a MOUDI sampler.The results of an analysis show that a beehive firework display emits significant amounts of PM 1 and PM 2.5 degrading, short-term air quality, requiring that related health concerns be addressed.

Collection of Particulates
Atmospheric particulate samples were collected in the YanShuei area of southern Taiwan during the Lantern Festival from February 21 to 25 in 2013.The windward sampling site was located on the roof of a three-story building (9 m height) in the Wumiao Temple, roughly 50 m north to the major beehive fireworks display site, while the leeward sampling site was located on the roof of a fourstory building (12 m height) in the YanShuei police station, roughly 300 m south to the major beehive fireworks display site.The YanShuei beehive fireworks display events occurred within the four stages of our experimental periods.In this investigation, it is regarded that February 21 st -22 nd , 23 th -24 th , 24 th (18:00-24:00), and 25 th 2013 were the before (background), trial, during, and after beehive fireworks display periods, respectively.The mean air temperature, relative humidity, and wind speed were 19.1°C (14.4-26.4°C),78.9% (56.0-94.0%),and 0.54 (0.0-2.2) m s -1 , respectively, during the sampling period (without any rain).
Silicon grease was applied to the surface of each filter installed in the MOUDI sampler, and the greased filterstrips were baked in a 60°C oven for 90 min to stabilize the silicon grease before sampling to minimize particle bounce between the different stages of the MOUDI during the sampling.Before and after each sampling, the filters were dried for 24 h in a desiccator at 25°C in 40% relative humidity.They were then weighed on an electronic balance (AND HM202) with a resolution of 10 µg.The suspended particulate matter concentration was determined by dividing the particle mass by the volume of sampled air.

Metals Analysis and Quality Control
Metals Analysis by Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) Particles were digested in a 1,600 W microwave oven (Mars, microwave digestion system, CEM) according to Yang and Swami (2007) and Tsai et al. (2003) to ensure accurate and reliable analysis of metals in the particles.The digested solution was a mixture of 10.0 mL (65% HNO 3 and 37% HCl) for Teflon filters.All reagents were prepared using chemicals supplied by Merck (Analytical grade).Inductively coupled plasmaoptical emission spectrometer (ICP-OES, ICP-OES Optima 2100DV, PerkinElmer) was used to analyze the metal concentrations.
Analytical drift was monitored throughout the procedure.Recovery efficiencies were determined and analyzed using a diluted sample spiked with a known quantity of metal.Recovery efficiencies from 93.7 to 100.8% were achieved.The method detection limit (MDL) was estimated by repeatedly analyzing a predefined quality control solution and by replicate analysis in ICP-OES measurements, the MDL of each element was calculated by MDL = 2.681 × S pooled , with S A 2 / S B 2 < 3.05.S pooled = [(6S A 2 + 6S B 2 )/12] 0.5 , where S pooled is the pooled standard deviation, S A the standard deviation of the one of two prepared samples with a bigger F-test value, and S B the standard deviation of the other.The detection limits in ng m -3 (calculated from MDL × volume of analyte solution (25 mL)/average sampling volume (40 m 3 )) were 16.8, 0.113, 0.719, 0.96, 2.35, 0.264, 0.066, 0.042, 0.154, 0.313, 0.047, 0.033, 0.050, and 0.018 for Na, Mg, Al, K, Ca, Fe, Cr, Ni, Zn, Sr, Ba, Pb, Mn, and Cu, respectively.

Concentrations of Metals in PM with Various Aerodynamic Diameters before and after Beehive Firework Display
Tables 1 and 2 present the concentrations of metals in particles before (background), on the rooftop of the Wumiao Temple (windward) and YanShuei police station (leeward) during and after a beehive firework display as part of the 2013 YanShuei Firework Festival.The mass concentration of PM 2.5 increased from 28.2 µg m -3 (background) to 437 µg m -3 during the beehive display on the leeward side, and from 26.1 µg m -3 to 165 µg m -3 on the windward side.At the windward sampling site, the PM 2.5 and PM 10 concentrations during the display reached approximately 4.7 and 4.9 times the background values, respectively, whereas at the leeward site, they were 12.5 and 4.6 times the national standards (35 and 125 µg m -3 , respectively).Joly et al. (2010) reported that the highest PM 2.5 levels during the 2007 Montréal International Fireworks Competition were almost 10,000 µg m -3 , which is approximately 1,000 times the background level.
Before beehive firework display (background), the total mean concentrations of 14 metals in PM 1.0 , PM 2.5 , and PM 10 particles were 349, 1016, and 3431 ng m -3 , respectively, at the leeward site and 2085, 2971, and 3785 ng m -3 , respectively, at the windward site.The major metals (30-100 ng m -3 ) in PM 1.0 , PM 2.5 , and PM 10 were Al, Ca, Fe, K, Na, and Zn (crustal metals and the metallic constituents of sea salt).During the displays, the metals that were generated at high concentration (≥ ~10 3 ng m -3 ) were Al, Ba, Cu, K, Na, and Sr.During the beehive firework display, the concentrations of metals in PM 2.5 (D) at leeward sampling site rise above the background level (B) to degrees that decrease in the order Ba (1,828 times), K (702 times), Sr (534 times), Cu (473 times), Mg (104 times), Al (121 In recent years, demand for fireworks of multiple colors has considerably increased the use of metals as color developers.Accordingly, during the beehive firework display, the mass concentrations of Ba (green coloring agent), Sr (red), Cu (blue) (Kulshrestha et al., 2004;Wang et al., 2007;Moreno et al., 2007;Perrino et al., 2011) in PM 2.5 at the leeward sampling site increased above their background values (Ba: 2.082; Sr: 2.745; Cu: 3.006 ng m -3 ) by 1828, 534 and 473 times, respectively (to Ba: 3,805; Sr: 1,466; Cu: 1,421 ng m -3 ) .
At the windward sampling site, the D/B values in PM 2.5 were, in decreasing order, Sr (×74), Ba (×68), K (×13), and Cu (×12).The concentrations of Ba, K, Cu, Mg, and Sr in the particulates were significantly higher at the leeward site than at the windward site.Most investigations of atmospheric PM emissions from fireworks have focused on Sr, Ba, and K as tracers of firework emissions (Liu et al., 1997;Kulshrestha et al., 2004;Drewnick et al., 2006;Moreno et al., 2007;Wang et al., 2007;Barman et al., 2008;Vecchi et al., 2008;Galindo et al., 2009;Joly et al., 2010).Barium compounds (BaClO 3 and Ba(NO 3 ) 2 ) are used as oxidizers.Both BaCO 3 and Ba(NO 3 ) 2 are used to create white effects or, in the presence of chlorine, bright green a firework color that is mostly associated with Ba (Lancaster et al., 1998;Perry, 1999).Potassium compounds (KNO 3 , KClO 4 , and KClO 3 ), which are used as propellants in fireworks, are the main oxidizers: in a firework display.Lin et al. (2014) found that the concentrations of Cl -in PM 1.0 , PM 2.5 , and PM 2.5-10 during a display were 91, 64, and 6.9 times higher than their background values.Furthermore, increases in measured K concentrations suggest that KClO 3 and KClO 4 are the major sources of oxygen in firecrackers.Both SrSO 4 and Sr(NO 3 ) 2 can be used as oxidizers, and, along with carbonate, impart a red color to fireworks when combined with chlorine.Finally, copper compounds such as the copper chloride and copper oxide produce a blue color, and can be mixed with strontium compounds to produce purple effects.CuCr 2 O 4 is used as a catalyst in rocket propellants (Lancaster et al., 1998).Although K, as a black powder fuel that is combined with S, dominates "special effect"trace additives can include various other metals such as Al, Cu, Ti, or even Pb (Hickey et al., 2010).Pb is of particular interest, given its high toxicity, as it is one of the few metals/metalloids for which legal atmospheric concentration limits exist (along with As, Hg, Ni, and Cd).Nevertheless, in many countries, laws against the use of Pb in the manufacture and combustion of fireworks are being thwarted by imports from countries that are less concerned with the potential health implications of their products.Some fireworks continue to contain Pb levels that are measurable in decigrams (Hickey et al., 2010).During a beehive firework display, the total Pb in PM 10 was 1,198 ng m -3 -higher than the air quality limit for Pb (500 ng m -3 ) that has been set by the World Health Organization (WHO, 2000).In the present investigation, the Pb concentrations in fine particles (1,150 ng m -3 ) and PM 1.0 (883.1 ng m -3 ) were found to be 24 and 18 times those in coarse particles.Therefore, the short-term exposure to firework sources should be concerned for adverse health effects because it is easier for fine-particulate Pb to enter and accumulate in the human respiratory system than for coarse-particulate Pb.

Ratios (T/B, D/B, and A/B) (Ratios of Values of Particle-Bound Metal Concentrations for Various PMs Before (Background (B)), Trail (T), During (D), and After (A) Beehive Firework Display of Particle-Bound metal Compositions for Different PMs
According to Fig. 1, the D/B ratios of particle-bound Ba, Cu, K, Mg, and Sr in PM 1.0 and PM 2.5 at the leeward sampling site were significantly higher than T/B and A/B during the beehive firework display.The maximal D/B values of Ba were 198 and 118 in PM 1.0 and PM 2.5 during the beehive fireworks display at that site.The D/B values for PM 1.0 and PM 2.5 were lower at the windward site.The maximal D/B value of Ba was 8.56 for PM 2.5 and the maximal D/B value of Sr was 8.85 for PM 1.0 .The D/B values of particle-bound Ca, Cr, Fe, Mn, Na, Ni, and Zn in PM 1.0 and PM 2.5 were less than corresponding T/B and A/B values at both leeward and windward sites.(Notably, the ratios for the metals compositions were all between zero and two.)This finding suggests that concentrations of particle-bound Al, Ba, Cu, K, Mg, Pb, and Sr increased during the beehive firework display, suggesting that firework aerosols are rich in Al, Ba, Cu, K, Mg, Pb, and Sr.
The above inference was examined by comparing the metal concentration distributions normalized to the concentrations of the upper continental crust (UCC) (Weckwerth, 2001) for the differently sized particles at the leeward and windward sampling sites during the sampling period (Fig. 2).The sampled PM 1.0 , PM 2.5 , and PM 10 particles all exhibited similar distributions of concentrations of the crustal metals (Al, Ca, Fe, Mg, and Na), normalized to UCC, for the trial, during, and after a beehive fireworks display at the leeward and windward sites; furthermore, these patterns were also similar to the background.Interestingly, the relative abundances of Ba, Cu, K, Pb, and Sr in PM 1.0 and PM 2.5 during the beehive firework display at the leeward site were very different to the background abundances, indicating that the beehive firework display emited more of these five metals in PM 1.0 and PM 2.5 .The concentrations of these five metals in PM 1.0 and PM 2.5 , relative to those in the UCC, in the trial, during, and after the beehive firework display at the windward site were close to the background values.

Size Distributions of Particulate Metals before and after the Beehive Firework Display
Fig. 3 presents the size distribution of particles of the major metals (Ba, K, Cu, Mg, Pb, and Sr) during four periods during the sampling period (February 21 st -22 nd , 23 th -24 th , 24 th (18:00-24:00), and 25 th , 2013 , which were before (background), trial, during, and after the beehive firework display, respectively).The results in the figure demonstrate that, at the leeward sampling site, the major metals exhibited approximately bi-modal size distributions with primary peaks in the 0.56-1.0µm range and secondary peaks in the coarse size range (3.2-5.6 µm) during the beehive firework display.At the leeward sampling site, before the beehive firework display (Background), the concentration of K exhibited a bi-modal size distribution, but those of the other major metals exhibited approximately single-modal size distributions with major peaks in the coarse particle range (3.2-5.6 µm).These distributions differed greatly from those during the beehive firework display.The major peaks in the size distribution of the metal particles clearly shifted from coarse particles to fine particles during the beehive firework display at the leeward site.
Fig. 4 displays cumulative mass fractions of the particlebound metals at the leeward and windward sampling sites.At the leeward sampling site, the ranges of mass ratios of the major metals to PM 2.5 and PM 1 were 19.0-55.3% and 2.8-43%, respectively, for the background and 74.5-95.3% and 56.5-72.9%,respectively, during the beehive firework display.At the leeward sampling site, the percentages of major metals (Ba, K, Cu, Mg, Pb, and Sr) in PM 1 and PM 2.5 during the beehive firework display exceeded the background value.Ba, K, Cu, Mg, Pb, and Sr, commonly regarded as firework display indicator elements (Vecchi et al., 2008;Joly et al., 2010;Crespo et al., 2012;Tsai et al., 2012;Kumar, et al., 2016), accounted for 0.520, 2.45, 26.4 and 0.849%, respectively, of the mass of PM 1 , and 0.777, 2.32, 23.8, and 0.776%, respectively, of the mass of PM 2.5 before (background), trial, during, and after the beehive firework display.Therefore, the mass ratios of these metals during the display were higher than the background values, trial, and the values of after the display.

Analysis of Particulate Metal Sources
Metal species with characteristic values of over 1 in Principal Component Analysis (PCA) (SPSS v.12.0) can be classified into several groups by their sources (Allen et al., 2001;Marcazzan et al., 2001;Manoli et al., 2002;Al-Momani, 2003;Azid et al., 2015;Chen et al., 2015;Fang et al., 2015;Liang et al., 2015).In each sampling period, the metal species, based on their characteristic values, exhibited three groups in PCA (Table 3).For the metal species in PM 2.5 before the beehive firework display, these three groups had characteristic values of 6.06, 5.68, and 1.25, corresponding to the potential sources of vehicles, resuspended dust, and wear of brake-linings/tires, respectively.The characteristic values in the particles during the trial beehive firework displays were 6.72, 3.85, and 1.44, revealing that their sources were fireworks, vehicles, and fuel oil, respectively.The fine particles also had three groups with characteristic values of 8.30, 4.06, and 1.22, referring to the sources of fireworks, resuspended dust, and fuel oil, respectively.The assessments of the firework source chemical profile and the effect of the fireworks display on the local environment represent an original contribution toward a better understanding of the aerosol characteristics and burdens during firework displays.After the beehive fireworks display, the fine particles had group characteristic values of 5.70, 5.40, and 1.17, corresponding to likely sources of resuspended dust, fireworks, and industry, respectively.The PCA analysis also revealed that the dominant metal elements of fine particles during fireworks were Al, Ba, Cr, Cu, K, Mg, Mn, Pb, Sr, and Zn.

CONCLUSIONS
In this study, the samples of metals in sized particles were collected using a MOUDI sampler in the YanShuei area of southern Taiwan during a beehive firework display.The results indicate that during the beehive firework display, the ratios of metal concentrations in PM 2.5 (D) to the background level (B) at leeward sampling site were 1,828 for Ba, 702 for K, 534 for Sr, 473 for Cu, 104 for Mg, 121 for Al, and 98 for Pb.The corresponding data for PM 1.0 were 3036, 838, 550, 676, 594, 190, and 126, respectively.According to the analyses of metal composition ratio, PCA, and UCC, the concentrations of particle-bound Al, Ba, Cu, K, Mg, Pb, and Sr increased during the beehive firework displays, suggesting that firework-display aerosols contained abundant metal elements of Al, Ba, Cu, K, Mg, Pb, and Sr.The Pb concentrations in fine particles (1,150 ng m -3 ) and PM 1.0 (883.1 ng m -3 ) were 24 and 18 times those in coarse particles, respectively.Therefore, the shortterm exposure to firework sources should be concerned for adverse health effects because it is easier for fine-particulate Pb to enter and accumulate in the human respiratory system than for coarse-particulate Pb.
The major peaks in the size distribution of the metal particles clearly shifted from coarse particles to fine particles during the beehive firework display at the leeward site.Before (background), trial, during, and after the beehive firework display, the Ba, K, Cu, Mg, Pb, and Sr (commonly regarded as firework display indicator elements) in PM 1 accounted for 0.520, 2.45, 26.4 and 0.849% of PM mass respectively, while in PM 2.5 the corresponding values were 0.777, 2.32, 23.8, and 0.776%, respectively.

LeewardFig. 1 .
Fig. 1.T/B, D/B, and A/B values and ratios of compositions of particle-bound metals in different particle size ranges at the leeward and windward sampling sites (B: background; D: during beehive fireworks display; A: after the display).

Fig. 2 .Fig. 3 .
Fig. 2. Metals distribution patterns (normalized to upper continental crust (UCC)) for the sized particles at the leeward and windward sampling sites.

Fig. 4 .
Fig. 4. Cumulative mass fractions of the particle-bound major metals at the leeward and windward sampling sites.

Table 1 .
Concentrations of metals in PM

Table 2 .
Concentrations of metals in PM

Table 3 .
Principal component analysis for the metals in PM 2.5 during the four sampling periods.Brake-lining/Tire rubbed off, V: Vehicles, F: Fireworks, I: Industry, O: Oil, and R: Resuspended dust.