Applying principal component, health risk assessment, source identification for metallic elements of ambient air total suspended particulates at Taiwan Scientific Park.

This study collected ambient air total suspended particle (TSP) concentrations and dry depositions at Taichung Science Park sampling site. The metallic elements concentrations and dry depositions were analyzed. The possible pollutant sources are discussed in this study. In addition, this study used the principal component analysis method to find metallic element sources and their transportation pathway and distributions at Taichung Science Park (T.S.P). The results indicated that the average highest TSP concentrations and dry deposition fluxes occurred in the autumn and winter seasons. The highest average metallic element concentration and dry deposition was Fe, while the lowest average metallic element concentration and dry deposition was Hg(p). The study results further indicated that the lowest metallic element concentrations and dry depositions all occurred in the summer season. The pollutant parcels originated from the northern Taiwan counties and sea surface in the autumn, winter and spring seasons. Factor 1 was responsible for the local industrial emission results and traffic road dust. The metallic elements Hg(p) yield a value greater than 0.7 in Factor 2 which revealed that ambient air particulate pollutants were generated from Taichung Thermal Power Plant (T.T.P.P.) emissions and were transported from the coastal area of mainland China cities. The mean seasonal concentration differences existed for ambient air particulates, and there were no mean seasonal concentrations differences for all metallic elements. In addition, there were no significant mean concentrations differences for all metallic elements and meteorological factors such as temperature, humidity and wind speed. Therefore, the ambient air metallic element emissions were stable and considered primary emissions sources. The health risk value for metallic element Cr was higher than that for the acceptable health risk value suggested by the EPA. Metallic element Cr revealed that it was no mean seasonal concentrations differences. Thus, metallic element Cr was considered came from local emission source at this T.S.P. sampling site.

Atmospheric Hg(p) concentrations at various particles sizes before (2018-2019) and during (2019-2020 and 2020-2021) COVID-19 occurred periods in Taichung, Taiwan.

The main goal of this study is to compare concentrations of atmospheric Hg(p) for various particles sizes Total Suspended Particulates (TSP), PM18, PM10, PM2.5, PM1, PM<1 before (2018-2019) and during (2019-2020 and 2020-2021) COVID-19 occurred periods in central Taiwan. In addition, test the statistical differences concentrations of Hg(p) for various particles sizes before and during COVID-19 occurred periods in central Taiwan. Finally, calculate the Hg(p) health risk assessment before and during COVID-19 occurred period in central Taiwan.The result indicated that the mean Hg(p) concentrations in TSP and PM2.5 were higher during (2020-2021) the COVID-19 occurred period than that of the mean Hg(p) concentrations in TSP and PM2.5 before the COVID-19 occurred period. In addition, the Hg(p)concentrations PM18, PM10, PM2.5, PM1 and PM<1 were all increased during the COVID-19 occurred period. The Hg(p) concentrations in TSP were decreased during (2019-2020) the COVID-19 occurred period when compared with that of the before the COVID-19 occurred period. Moreover, significant mean Hg(p) concentrations differences were existed at PM18, PM10 and PM2.5 before and during (2020-2021) COVID-19 occurred periods. Finally, the HQ and HI values for Hg(p) were both increased during COVID-19 occurred periods when compared with before COVID-19 occurred period in this study.

Concentrations, sizes distributions, and seasonal variations of ambient air pollutants (particulates, trace metals) in Daya/Xitun District, Taichung, Central Taiwan: a case study at Taichung Science Park.

Taichung Science Park in central Taiwan releases ambient air pollutants to the atmosphere. This issue has attracted much attention over the past few years. This study concerns seasonal concentrations of atmospheric particles and metallic elements and particle size distributions. A M.O.U.D.I sampler is used at a Taichung Science Park sampling site to obtain relevant data. Fe, followed by Al, had the highest average metallic element concentrations in particles of various sizes (PM18, PM10, PM2.5, PM1 and PM<1(0.3)); Cd had the lowest. The average concentrations of metallic elements in particles of various sizes were lowest in the summer. Fe, Al and Cr had the three highest concentrations among all metallic elements for all particles sizes in all seasons. Ambient air particulate pollutants (crustal and anthropogenic metallic elements) were released from a single emission source at Taichung Science Park site.

Ambient air particulates and Hg(p) concentrations and dry depositions estimations, distributions for various particles sizes ranges.

Ambient air TSP concentrations, dry deposition fluxes and particulate-bound mercury (Hg(p)) concentrations were measured and analyzed at a complex (traffic, residential and commercial) site. Zhang and He's model[1] was used to predict the dry deposition fluxes of ambient air particulates and Hg(p) at this complex site. The results revealed that October had the highest mean particulate concentration and lowest Hp(p) concentration and dry deposition flux. The mean calculated dry deposition fluxes of PM2.5 and PM2.5-10 accounted for 1%-2% and 0.06%-5% of the average total calculated dry deposition particle flux, respectively. The average calculated particle dry depositions flux of PM10+, accounted for 93%-99% of the average total calculated dry depositions particle flux. Finally, the model of Zhang and He underestimated the ambient air dry depositions fluxes of both particulates and Hg(p) for all particles sizes (PM2.5, PM2.5-10, PM10+) at the mixed site in this study. Better results concerning the dry deposition fluxes of pollutants were obtained as the particles size increased.

Mercury wet depositions study at suburban, agriculture and traffic sampling sites.

This study aimed to measure and discuss the relationship of ambient air precipitations with respect to mercury wet depositions at suburban, agriculture and traffic three characteristic sampling sites during the year of 2019. In addition, the mercury volume weighted mean concentrations (VWM) at three characteristic sampling sites were also calculated. Finally, the ambient mercury wet depositions data obtained in this study to various world sampling sites were also compared and discussed in this study. The results indicated that the average mercury wet depositions for suburban, agriculture and traffic areas were 0.62, 0.55 and 2.32 ng/m2 min, respectively. And the average mercury VWM values were 0.9, 0.72 and 1.85 ng/m2 min for suburban, agriculture and traffic sites, respectively. In addition, the highest VWM and wet depositions for mercury both occurred in March at traffic and suburban areas. And the mercury wet depositions displayed a declined trend when the month was moved from March to July at both traffic and suburban sampling sites. In addition, the relationship between wet depositions and precipitations was low to moderate correlated in traffic area, while the relationship between wet depositions and precipitations was insignificant at both suburban and agriculture areas. Moreover, the average highest mercury wet deposition occurred in Nepal when compared to the other world sites. In addition, the average value of mercury wet depositions in Nepal was about 17.23 times to that of data obtained in this study during the period of 2007-2019. Finally, the average highest VWM (ng/L) occurred in the China. In addition, the average value mercury VWM in China was about 14.82 times to that of data obtained in this study during the period of 2007-2019.

Particulate and particulate-bound mercury concentrations and size distributions as related to seasonal variations during peak demand/non-peak demand periods.

The particulate size distributions of aerosol pollutants (particulates and Hg(p)) at a mixed site were measured and their seasonal variations identified. Atmospheric particulates and the Hg(p) mass median diameter (m.m.d.) were obtained. Hg(p) concentrations increased by approximately 20% during the peak demand period for all particle sizes (18, 10, 2.5, 1 and 0.3 µm). The mean percentage concentration of Hg(p) was highest in summer and followed the order summer > spring > winter > autumn for all particle sizes. Hg(p) concentration exhibited increased from 2004 to 2019.

Particulates and particulates-bound mercury (Hg(p)) sizes (PM18, PM10, PM2.5, PM1, PM<1) distributions study by using MOUDI sampler at a complex sampling site.

The objectives of this study were to measure ambient air particles concentrations of different particulates sizes ranges (PM18, PM10, PM2.5, PM1, PM<1) at a complex (traffic, residential and commercial) site. Besides, particulates-bound mercury (Hg(p)) concentrations for various particulates sizes (PM18, PM10, PM2.5, PM1, PM<1) at mixed site were also studied. Finally, ambient air particulates and Hg(p) size distributions were also described at this complex sampling site. The results showed that the average PM18, PM10, PM2.5, PM1, PM<1 concentrations were 48.83, 41.78, 35.41, 19.89, and 11.86 µg/m3, respectively. And the average ambient air particulates-bound mercury (Hg(p)) which attached on PM18, PM10, PM2.5, PM1, PM<1 particles concentrations were 0.0838, 0.0867, 0.0790, 0.0546, and 0.0373 ng/m3, respectively, in the summer season. In addition, the average ambient air Hg(p) which attached on PM18, PM10, PM2.5, PM1, PM<1 particles concentrations were 0.0175, 0.0144, 0.0120, 0.0092, and 0.0057 ng/m3, respectively, in the autumn season. Finally, the average ambient air Hg(p) which attached on PM18, PM10, PM2.5, PM1, PM<1 particles concentrations were 0.0070, 0.0053, 0.0038, 0.0026, and 0.0014 ng/m3, respectively, in the winter season. And July has the average highest PM18 and PM10 concentrations. As for PM2.5, PM1 and PM<1 particulates, the average highest particulates concentrations all occurred in November. In addition, the highest average Hg(p) in PM18, PM10, PM2.5, PM1, and PM<1 concentrations all occurred in July. Moreover, the average particles and particulates-bound mercury m.m.d. values were ranged from 1.0 to 1.8 and 0.7 to 2.0 µm from July to December of 2018, respectively, at this mixed sampling site. As for monthly ambient air particles sizes distributions, the results further showed that the main peaks for July, September, and December all occurred in the sizes of 10-18 µm. The main peaks for October and November all occurred in the sizes of 2.5-10 µm. As for monthly Hg(p) sizes distributions, the results further showed that the main peaks for July occurred in the size of 0.3-1 µm. The main peak for September occurred in the size of 1-2.5 µm. The main peaks for October to December all occurred in the size of 10-18 µm. The above finding further concluded that the particulates-bound mercury (Hg(p)) was tended to be associated with the large particles sizes mode during the winter season. Finally, this study further shows that the Taichung Thermal Power Plant was responsible for the main emission source of Hg(p) especially in summer season of Central Taiwan.

Sources and monthly and seasonal concentration variation study of atmospheric particulates and particles-bound PAEs.

The main goal of this study is to measure the ambient air of total suspended particulates at a mixed (traffic, residential and commercial) sampling site. And the concentrations of phthalate acid ester (PAE) which attached on total suspended particles were also analyzed. In addition, the possible sources of PAEs were also analyzed by the method of back trajectories. Finally, appropriate statistical methods were also used to test monthly and seasonal mean pollutants' (particulates, PAEs) concentration differences at this sampling site. The results indicated that the monthly concentration variation trends were similar for DEHP and total PAEs with the results as followed: November > October > July > December > September. In addition, back trajectories results also indicated that the main pollutant parcels were came from the east side of Taiwan in July. And the pollutant parcels were came from the north side of Taiwan during the month of September, October, November and December in this study. Moreover, the results also showed that the DEHP, DNOP, total PAEs' concentrations with TSP and meteorological conditions were not significantly different. But the relationship among DEHP, DNOP and total PAEs was significantly different; particularly, the relationship between DEHP and total PAEs was highly correlated in this study (R2 = 0.994). Finally, the statistical analysis of total PAEs T test statistic for mean monthly concentrations results suggested that the sample population means were not differed significantly. In other words, there were not any mean monthly concentration differences for PAEs at this sampling site. The only exception was occurred in the month of September versus November. The results showed that there is a statistically significant PAEs' concentration difference between the input groups (September vs. November).

Ambient air particulates-bound metallic elements sources identifications during winter and summer at a Science Park.

The ambient air particulates pollutants of total suspended particulates (TSP) and PM2.5 were collected by using PS-1 and Wilbur PM2.5 sampler, simultaneously during the year of 2015-2017 at a photoelectric factory in Science Park of central Taiwan. And those of the ambient air atmospheric metallic elements (Cr, Mn, Ni, Cu, Zn, Pb) concentrations which attached on the TSP and PM2.5 were analyzed by using inductively coupled plasma optical emission spectrometer. In addition, identifying anthropogenic and natural pollutants sources were conducted by using the enrichment factor (EF) and principal component analysis (PCA) methods. The results indicated that the average TSP and PM2.5 concentrations were ranked highest in winter season, while summer season was ranked lowest during the year of 2015-2016. In addition, the average highest metallic element concentrations were occurred in winter season for both TSP and PM2.5 during the year of 2015-2016, while the average lowest metallic elements concentrations in TSP and PM2.5 were also occurred in winter season during the year of 2016-2017. Moreover, the EF analysis results showed that the metallic element Zn came from anthropogenic emission source. As for metallic element Mn, the results showed that metallic element Mn was mainly attributed to natural emission in this study. Finally, the PCA results showed that metallic elements Cr, Zn and Pb were the dominant emissions metallic elements in this study. As for PM2.5, the results showed that the metallic elements Cr, Cu and Pb were the dominant emissions metallic elements at this HPB sampling site.

Wet depositions of mercury during plum rain season in Taiwan.

The plum rain season in Taiwan is in May and June. The severest plum rain season over the last 21 years was in 2017. This study involves the collection of mercury wet depositions in the plum rain season of May-June in 2017. A DMA-80 (Direct Mercury Analyzer) was used to analyze the precipitated mercury concentrations and calculate the wet depositions of mercury in the plum rain season. The results indicate that the highest wet depositions of mercury in the aqueous phase were on 6/16, reaching 209.04 µg/m2 * day, while the lowest were on 5/15, at 0.18 µg/m2 * day. The mercury wet depositions in the particulate phase were highest on 6/17, when it exceeded 100 µg/kg, and lowest on particulate phase were occurred in 6/11, when it was 3.64 µg/m2 * day. The relationship between the wet depositions of mercury in the aqueous phase and rainfall was insignificant, while that between the wet depositions of mercury in the particulate phase and rainfall was significant. The wet depositions of mercury in this study were second highest (30.73 µg/m2 day) when compared with those in studies in the years 2007-2017. Although the rainfall in this study was only 564 mm H2O, high mercury concentrations obtained from the plum rain season result in the high wet depositions of mercury in Taichung, Taiwan.

Review of total suspended particles (TSP) and PM2.5 concentration variations in Asia during the years of 1998-2015.

In Asian countries such as China, Malaysia, Pakistan, India, Taiwan, Korea, Japan and Hong Kong, ambient air total suspended particulates and PM2.5 concentration data were collected and discussed during the years of 1998-2015 in this study. The aim of the present study was to (1) investigate and collect ambient air total suspended particulates (TSP) and PM2.5 concentrations for Asian countries during the past two decades. (2) Discuss, analyze and compare those particulates (TSP and PM2.5) annual concentration distribution trends among those Asian countries during the past two decades. (3) Test the mean concentration differences in TSP and PM2.5 among the Asian countries during the past decades. The results indicated that the mean TSP concentration order was shown as China > Malaysia > Pakistan > India > Taiwan > Korea > Japan. In addition, the mean PM2.5 concentration order was shown as Vietnam > India > China > Hong Kong > Mongolia > Korea > Taiwan > Japan and the average percentages of PM2.5 concentrations for Taiwan, China, Japan, Korea, Hong Kong, Mongolia and Other (India and Vietnam) were 8, 21, 6, 8, 14, 13 and 30%, respectively, during the past two decades. Moreover, t test results revealed that there were significant mean TSP and PM2.5 concentration differences for either China or India to any of the countries such as Taiwan, Korea and Japan in Asia during the past two decades for this study. Noteworthy, China and India are both occupied more than 60% of the TSP and PM2.5 particulates concentrations out of all the Asia countries. As for Taiwan, the average PM2.5 concentration displayed increasing trend in the years of 1998-1999. However, it showed decreasing trend in the years of 2000-2010. As for Korea, the average PM2.5 concentrations showed decreasing trend during the years of 2001-2013. Finally, the average PM2.5 concentrations for Mongolia displayed increasing trend in the years of 2004-2013.

Concentrations and analysis of health risks of ambient air metallic elements at Longjing site in central Taiwan.

The concentrations of particulates and metallic elements that were bound to total suspended particulates in ambient air at Long Cyuan Elementary School (LCYES), Lung Ching Elementary School (LCHES) and Long Shan Primary School (LSPS) sampling sites in the Longjing area were measured. Significant difference tests were conducted at LSPS, LCYES and LCHES sites. Finally, carcinogenic and non-carcinogenic risk values for LSPS, LCYES and LCHES sites in the Longjing district were evaluated. The results show that the most average particulate and metallic element concentrations were highest in October, November, January, February, March, April, August, and September The average particulate and metallic element concentrations at LCHES were higher than at the other sampling sites. The Concentration Scatter Diagrams reveal the absence of significant variation among the LSPS, LCYES and LCHES sampling sites in the Longjing district. Therefore, these sampling sites are inferred to have similar emission sources. The children and adults inhalation carcinogenic risks which referenced US EPA method were all within acceptable ranges. Non-carcinogenic risks revealed that all metallic elements considered herein were harmless to human health.

Ambient PM2.5 in the residential area near industrial complexes: Spatiotemporal variation, source apportionment, and health impact.

This study systemically investigated the ambient PM2.5 (n=108) with comprehensive analyses of the chemical composition, identification of the potential contributors, and estimation of the resultant respiratory physician visits in the residential regions near energy-consuming and high-polluting industries in central Taiwan. The positive matrix fraction (PMF) model with chemical profiles of trace metals, water-soluble ions, and organic/elemental carbons (OC/EC) was applied to quantify the potential sources of PM2.5. The influences of local sources were also explored using the conditional probability function (CPF). Associations between the daily PM2.5 concentration and the risk of respiratory physician visits for the elderly (≥65years of age) were estimated using time-series analysis. A seasonal variation, with higher concentrations of PM2.5, metals (As, Cd, Sb, and Pb), OC/EC and ions (i.e., NO3-, SO42- and NH4+) in the winter than in the spring and summer, was observed. Overall, an increase of 10µgm-3 in the same-day PM2.5 was associated with an ~2% (95% CI: 1.5%-2.5%) increase in respiratory physician visits. Considering the health benefits of an effective reduction, we suggest that the emission from coal combustion (23.5%), iron ore and steel industry (17.1%), and non-ferrous metallurgy (14.4%), accounting for ~70% of the primary PM2.5 in the winter are prioritized to control.

Seasonal variations and sources study by way of back trajectories and ANOVA for ambient air pollutants (particulates and metallic elements) within a mixed area at Longjing, central Taiwan: 1-year observation.

This study measured the concentrations of particulates and metallic elements in ambient air by using PS-1 sampler (TSP) at Longjing area. And this study focuses on the collection of ambient air particulates, metallic elements, particulate-bound mercury Hg(p), concentrations. In addition, the sources of ambient pollutants by way of back trajectory analysis are found. Moreover, test mean concentration variance differences for metallic elements (PM, Hg(p), Mn, Fe, Zn, Cr, Cu, and Pb) among the four seasons (spring, summer, autumn and winter) through ANOVA are calculated. The result indicates that the average highest particulate concentration occurred in winter season, and the order was winter > spring > autumn > summer, and the mostly highest average metallic element (Mn, Fe, Zn, Cr, Cu, Pb) concentrations occurred in autumn. Moreover, the mostly average lowest metallic element concentrations occurred in summer. In addition, the above results of backward trajectories that the major particulate pollutants parcel mainly come from northeastern Taiwan. Moreover, when comparing the results of the first half year to that of the second half year, the they indicated that all metallic elements displayed significant differences in concentrations except those of Hg(p), Mn, Fe, Zn. Finally, metallic element Hg(p) is the only one which showed no significant concentration difference from either seasonal variations or half-year observations.

Study of the ambient air metallic elements Cr, Cu, Zn, Cd and Pb at HAF sampling sites.

This study characterized diurnal variations in the compositions of total suspended particulates (TSP) and dry deposits of particulates from ambient air, and the metallic elements that are contained in them at harbor, airport and farmland (HAF) sampling sites from August, 2013 to July, 2014. Two-way ANOVA of the amounts of metallic elements in the TSP and dry deposits was carried out in all four seasons at the HAF sampling sites. The metallic elements Cr and Cu originated in local emission sources at the airport. Metallic elements Zn and Pb originated in local emission sources at the harbor. Finally, metallic element Cd originated in local emissions form farmland. The following results were also obtained. (1) The metallic composition of the TSP differed significantly from that of the dry deposits in all four seasons at the harbor and farmland sampling sites, but not at the airport sampling site. (2) High correlations coefficients were found between the amounts of metallic elements Cr and Cu in the TSP and those in the dry deposits at the airport sampling site. (3) Pb was present in the TSP and the dry deposits at the harbor sampling site.

PM2.5 particulates and metallic elements (Ni, Cu, Zn, Cd and Pb) study in a mixed area of summer season in Shalu, Taiwan.

PM2.5 has become an important environmental issue in Taiwan during the past few years. Moreover, electricity increased significantly during the summertime and TTPP generated by coal burning base is the main electricity provider in central Taiwan. Therefore, summer season has become the main research target in this study. The ambient air concentrations of particulate matter PM2.5 and PM10 collected by using VAPS at a mixed characteristic sampling site were studied in central Taiwan. The results indicated that the average daytime PM2.5 and PM10 particulate concentrations were occurred in May and they were 44.75 and 57.77 µg/m3 in this study. The results also indicated that the average nighttime PM2.5 and PM10 particulate concentrations were occurred in June and they were 38.19 and 45.79 µg/m3 in this study. The average PM2.5/PM10 ratios were 0.7 for daytime, nighttime and 24-h sampling periods in the summer for this study. This value was ranked as the lowest ratios when compared to the other seasons in previous study. Noteworthy, the results further indicated that the metallic element Pb has the mean highest concentrations for 24-h, daytime and nighttime sampling periods when compared to those of the other metallic elements (Ni, Cu, Zn and Cd). The average mean highest metallic Pb concentrations in PM10 were 110.7, 203.0 and 207.2 ng/m3 for 24-h, daytime and nighttime sampling periods in this study. And there were 59.53, 105.2 and 106.6 ng/m3 for Pb in PM2.5 for 24-h, daytime and nighttime sampling periods, respectively. Moreover, the results further indicated that mean metallic element Pb concentrations on PM2.5 and PM10 were all higher than those of the other elements for 24 h, day and nighttime.

Annual ambient atmospheric mercury speciation measurement from Longjing, a rural site in Taiwan.

The main purpose of this study was to monitor ambient air particulates and mercury species [RGM, Hg(p), GEM and total mercury] concentrations and dry depositions over rural area at Longjing in central Taiwan during October 2014 to September 2015. In addition, passive air sampler and knife-edge surrogate surface samplers were used to collect the ambient air mercury species concentrations and dry depositions, respectively, in this study. Moreover, direct mercury analyzer was directly used to detect the mercury Hg(p) and RGM concentrations. The result indicated that: (1) The average highest RGM, Hg(p), GEM and total mercury concentrations, and dry depositions were observed in January, prevailing dust storm occurred in winter season was the possible major reason responsible for the above findings. (2) The highest average RGM, Hg(p), GEM and total mercury concentrations, dry depositions and velocities were occurred in winter. This is because that China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. (3) The results indicated that the total mercury ratios of Kaohsiung to that of this study were 5.61. This is because that Kaohsiung has the largest industry density (~60 %) in Taiwan. (4) the USA showed average lower mercury species concentrations when compared to those of the other world countries. The average ratios of China/USA values were 89, 76 and 160 for total mercury, RGM and Hg(p), respectively, during the years of 2000-2012.

Ambient air particulates and particulate-bound mercury Hg(p) concentrations: dry deposition study over a Traffic, Airport, Park (T.A.P.) areas during years of 2011-2012.

The main purpose of this study was to monitor ambient air particles and particulate-bound mercury Hg(p) in total suspended particulate (TSP) concentrations and dry deposition at the Hung Kuang (Traffic), Taichung airport and Westing Park sampling sites during the daytime and nighttime, from 2011 to 2012. In addition, the calculated/measured dry deposition flux ratios of ambient air particles and particulate-bound mercury Hg(p) were also studied with Baklanov & Sorensen and the Williams models. For a particle size of 10 µm, the Baklanov & Sorensen model yielded better predictions of dry deposition of ambient air particulates and particulate-bound mercury Hg(p) at the Hung Kuang (Traffic), Taichung airport and Westing Park sampling site during the daytime and nighttime sampling periods. However, for particulates with sizes 20-23 µm, the results obtained in the study reveal that the Williams model provided better prediction results for ambient air particulates and particulate-bound mercury Hg(p) at all sampling sites in this study.

An Environmentally Friendly Method for Testing Photocatalytic Inactivation of Cyanobacterial Propagation on a Hybrid Ag-TiO2 Photocatalyst under Solar Illumination.

Cyanobacteria were inactivated under sunlight using mixed phase silver (Ag) and deposited titanium dioxide (TiO2) coated on the surface of diatomite (DM) as a hybrid photocatalyst (Ag-TiO2/DM). The endpoints of dose-response experiments were chlorophyll a, photosynthetic efficiency, and flow cytometry measurements. In vitro experiments revealed that axenic cultures of planktonic cyanobacteria lost their photosynthetic activity following photocatalyzed exposure to sunlight for more than 24 h. Nearly 92% of Microcystis aeruginosa cells lost their photosynthetic activity, and their cell morphology was severely damaged within 24 h of the reaction. Preliminary carbon-14 ((14)CO3(-2)) results suggest that the complete inactivation of cyanobacteria arises from damage to cell wall components (peroxidation). A small concomitant increase in cell wall disorder and a consequent decrease in cell wall functional groups increase the cell wall fluidity prior to cell lysis. A high dosage of Ag-TiO2/DM during photocatalysis increased the concentration of extracellular polymeric substances (EPSs) in the Microcystis aeruginosa suspension by up to approximately 260%. However, photocatalytic treatment had a small effect on the disinfection by-product (DBP) precursor, as revealed by only a slight increase in the formation of trihalomethanes (THMs) and haloacetic acids (HAAs).

A measurement of summertime dry deposition of ambient air particulates and associated metallic pollutants in Central Taiwan.

The purpose of this study is to characterize metallic elements associated with atmospheric particulate matter in the dry deposition plate, total suspended particulate, fine particles, and coarse particles at Taichung Harbor and Gong Ming Junior High School (airport) in central Taiwan at a sampling site from June 2013 to August 2013. The results indicated that: (1) the average concentrations of the metallic elements Cr and Cd were highest at the Gong Ming Junior High School (airport), and the average concentrations of the metallic elements Ni, Cu, and Pb were highest at the Taichung Harbor sampling site. (2) The high smelting industry density and export/import rate of heavily loaded cargos were the main reasons leading to these findings. (3) The average metallic element dry deposition and metallic element PM(2.5-10) all followed the order of Pb > Cr > Cu > Ni > Cd at the two sampling sites. However, the average metallic elements Cu and Pb were found to have the highest dry deposition velocities and concentrations in PM(2.5) for the two sampling sites in this study. (4) The correlation coefficients of ambient air particle dry deposition and concentration with wind speed at the airport were higher than those from the harbor sampling site. The wind and broad open spaces at Taichung Airport were the possible reasons for the increasing correlation coefficients for ambient air particle concentration and dry deposition with wind speed at the Taichung Airport sampling site.