Measurement of Total Free Iron in Soils by H2S Chemisorption and Comparison with the Citrate Bicarbonate Dithionite Method.

Free iron is one of the major analytical items for soil basic properties. It is also an important indicator for understanding the genesis of soil, soil classification, and soil distribution behavior. In this study, an alternative analytical method (chemisorption) based on thermodynamic knowledge was proposed for measurement of total free iron oxides in soils. Several representative soil samples belonging to alfisols, ultisols, inceptisols, and entisols were collected from Taiwan and tested by the chemisorption, and the estimated total free iron oxides were compared with those measured from the traditional citrate bicarbonate dithionite (CBD) method. Experimental results showed that the optimal operating temperature was found to be at 773 K and the carbon monoxide (CO) is the best gaseous reagent to promote the formation of FeS. The estimated total free iron oxides for soil samples determined from the chemisorption in the presence of CO were very close to those from the CBD technique. The result of regression indicates that the estimated total free iron is strongly correlated with the CBD-Fe content (R2 = 0.999) in the presence of CO.

Carbon Dioxide Concentrations and Temperatures within Tour Buses under Real-Time Traffic Conditions.

This study monitored the carbon dioxide (CO2) concentrations and temperatures of three 43-seat tour buses with high-passenger capacities in a course of a three-day, two-night school excursion. Results showed that both driver zones and passenger zones of the tour buses achieved maximum CO2 concentrations of more than 3000 ppm, and maximum daily average concentrations of 2510.6 and 2646.9 ppm, respectively. The findings confirmed that the CO2 concentrations detected in the tour buses exceeded the indoor air quality standard of Taiwan Environmental Protection Administration (8 hr-CO2: 1000 ppm) and the air quality guideline of Hong Kong Environmental Protection Department (1 hr-CO2: 2500 ppm for Level 1 for buses). Observations also showed that high-capacity tour bus cabins with air conditioning system operating in recirculation mode are severely lacking in air exchange rate, which may negatively impact transportation safety. Moreover, the passenger zones were able to maintain a temperature of between 20 and 25°C during travel, which effectively suppresses the dispersion of volatile organic compounds. Finally, the authors suggest that in the journey, increasing the ventilation frequency of tour bus cabin, which is very beneficial to maintain the travel safety and enhance the quality of travel.

Inorganic arsenic exposure and its relation to metabolic syndrome in an industrial area of Taiwan.

Past arsenic exposure was found associated with increased incidence of type 2 diabetes. However, the mechanisms remain unclear. Metabolic syndrome has been shown as a strong predictor for diabetes occurrence. We aimed at examining the association of inorganic arsenic exposure and the prevalence of metabolic syndrome. The authors recruited 660 age and gender stratified random population of residents in central Taiwan during 2002-2003. They received home interviews and health examinations at local health care units, where blood and hair specimens were collected. Hair arsenic (H-As) concentrations were determined by inductively coupled plasma-mass spectrometry. Metabolic syndrome was defined as the presence of three or more of the following risk factors: elevated levels of blood pressure, plasma glucose, and triglycerides, also the body mass index, and reduced high-density lipoprotein. Prevalence of metabolic syndrome increased from the 2nd tertile (0.034 ug/g) of H-As levels (odds ratio=2.54, 95% confidence interval: 1.20-5.39, p=0.015) after the adjustment for age, gender, occupation and life styles including cigarette smoking. We further found linear relation between H-As concentrations and increased levels of plasma glucose and lipids, and blood pressures. This first report may help identify modifiable factors associated with diabetogenesis and cardiovascular disease progression and thus be worth following for community health.

Burning characteristics and emission products related to metallic content in incense.

This study mainly compared particulate emission factors of nine popular incense. The influence of metallic contents upon the burning rate, ash and particulate emission factors of combustion was discussed. The contents of Ca and K were the highest among all metallic elements in the raw materials of the incense (the geometric mean contents 8.7 and 2.5mgg(-1), respectively), followed by Al, Mg, Fe, Na (0.1-1.0mgg(-1)) and Ba, then Sr, Mn, Cu and Zn (<0.01-0.1mgg(-1)). Most calcium existed as inorganic salts, such as CaCO(3). Under the same burning conditions, the particulate generation rates are similar (0.50mgmin(-1)+/-9%) among different types of incense-the shorter the combustion duration of a stick, the lower the total suspended particulate emission. Additionally, with the same incense weight burned, the greater the emission of ash is, the lower the emission of suspended particulate. It is recommended that consumers select incense which produces more ash, hence less particulate, to minimize the threat to their' health. Additionally, when the total metallic content (with Ca as the major component) was lower than 2% of the raw materials, properly increasing the total metallic content (from 0.5 to 2.0%) can effectively reduce the level of particulates (about 40%) during the combustion.

Particle size distribution and PAH concentrations of incense smoke in a combustion chamber.

The particle size distribution and the concentrations of polycyclic aromatic hydrocarbons (PAHs) in incense smoke were studied using a custom-designed combustion chamber. Among the nine types of incense investigated, the particle and the total PAH emission factors varied significantly. The average mass median aerodynamic diameter (MMAD) of the smoke aerosol was 262+/-49nm, which positively correlated to particle emission factor (mg/stick, p<0.05). Coagulation was a major mechanism that dictates the MMAD of the smoke. The total toxic equivalency (the sum of the benzo[a]pyrene equivalent concentration) of the solid-phase PAHs (S-PAHs) was over 40 times higher than that of the corresponding gas-phase PAHs, indicating that the S-PAHs in incense smoke may pose potential health risk. Experiments show that each lowered percentage of total carbon content in the raw incense helped decrease the particle emission factor by 2.6mg/g-incense, and the reduction of S-PAH emission factor ranged from 8.7 to 26% when the carbon content was lowered from 45 to 40%.

Survey of urinary nickel in residents of areas with a high density of electroplating factories.

The soil metal contamination arising from the discharge of the high density of electroplating factories in the geographic center of Taiwan has prompted concern about human exposure to harmful metals. This study aimed to determine the levels of nickel (Ni) in urine of residents living in the high vs. low factory-density areas, and to examine how these levels relate to gender and age. A total of 660 subjects, resident in the area for the last five years, were sampled according to the stratified random sampling approach, at ages 35-44, 45-54, and 55-64years for both genders. Metals in urine samples were analyzed by inductively coupled plasma mass spectrometry (ICPMS). The geometric mean (95% confidence interval (CI)) of urinary Ni was 6.30 (5.99-6.62)mug/l. The 0.95 parametric reference interval (90% CI) of urinary Ni was estimated to be 1.74 (1.62-1.88) to 22.73 (21.14-24.44)mug/l. Subjects in the areas with a high density of electroplating factories had significantly higher urinary Ni levels than those in the low-density areas, but both types of areas had obviously higher urinary Ni levels when compared to the non-occupationally exposed population from western countries. The health significance of elevated urinary Ni and its causative factors remain to be determined.

Biomonitoring of chromium for residents of areas with a high density of electroplating factories.

The high density of electroplating factories in the geographic middle of Taiwan has prompted concern over the potential for exposure to harmful metals. The present study aimed to determine the levels of chromium in whole blood (B-Cr) of residents living in the high vs. low factory-density areas, and to examine the relations to gender and age. A total of 660 residents who had not moved within the 5 years preceding the study were sampled according to the stratified random sampling approach, at ages 35-44, 45-54, and 55-64 years, for both genders. Chromium determinations (n=641) were made using a graphite furnace atomic absorption spectrometer. The geometric mean (95% C.I.) of B-Cr was 0.357 (0.34-0.38) microg/l. The International Federation of Clinical Chemistry (IFCC) nonparametric 0.95 reference limits of B-Cr was estimated to be <0.905 microg/l. B-Cr levels decreased with increasing age. Subjects in the areas with a high density (0.38 microg/l, 95% C.I.: 0.36-0.40) of electroplating factories had significantly higher B-Cr levels, compared to residents of the low-density (0.27, 0.25-0.30) areas and to the general population from western countries. The health significance of the elevated B-Cr remains to be determined.

Correlation between calcium carbonate content and emission characteristics of incense.

In Taiwan and China, calcium carbonate is commonly added as a filler during incense production to lower the cost. This study has found an unexpected benefit for this practice: it reduces particulate emission. Nine types of the popular incense on the local market were chosen for this study. The calcium content in raw material incense was analyzed by inductively coupled plasma atomic emission spectrometry, followed by X-ray diffraction (XRD) spectroscopy. The correlation between the calcium content and emission characteristics of incense was investigated. The calcium content varied from 1.8 to 60 mg/g (incense burned) among those nine different types of incense. Very little calcium (< 1%) was found in natural wood or plants, which is mainly the raw material of incense. Instead, most calcium was artificially added in the form of CaCO3 during manufacturing. The combustion characteristics, including burning rate, emission factors of particulate, ash, and solid-phase polycyclic aromatic hydrocarbons (S-PAHs), varied significantly among the nine types of incense. Incense containing 2% calcium would emit 30% less S-PAHs, compared with those with little (< 0.2%) calcium. More importantly, increasing the calcium content from 0.5 to 5% by adding CaCO3 reduced the particulate emission from incense by approximately 50%.

Characteristics of polycyclic aromatic hydrocarbons and total suspended particulate in indoor and outdoor atmosphere of a Taiwanese temple.

Incense burning, a common and popular practice among many families and in most temples in Taiwan, can result in indoor pollution-related health problems. This exploratory study was aimed at characterizing human exposure to polycyclic aromatic hydrocarbons (PAHs) and total suspended particulate (TSP) inside and around a Taiwanese temple, and to compare the indoor levels with levels outside. Additionally, three types of commonly used unburned incense and incense ash were analyzed in order to evaluate the relationship between incense composition and PAH emissions.Standard methods were used to determine air concentrations of 21 PAHs and TSP inside and around a chosen temple. Indoor mean total-PAH concentration, particle-bound PAH concentration and TSP concentration were 6258 ng/m(3), 490 micro g/g and 1316 micro g/m(3), respectively; values for outdoor readings were 231 ng/m (3), 245 micro g/g and 73 micro g/m(3), for outdoors, respectively indicating PAH and TSP concentrations inside 27 and 18 times greater, respectively than outdoors. With respect to concentrations of individual PAHs (particulate+gas phase), the five highest concentrations were of acenaphthylene (AcPy) (3583 ng/m(3)), naphthalene (Nap) (1264 ng/m(3)), acenaphthene (Acp) (349 ng/m(3)), fluoranthene (FL) (243 ng/m(3)) and phenanthrene (PA) (181 ng/m(3)). Median values for indoor/outdoor (I/O) ratios of individual PAHs ranged from 5.7 to 387.9, which implied that the temple was a significant PAH source. Moreover, PAH content of the tested stick incense and ash was very low. PAH levels inside the temple were much higher than those measured in the vicinity and inside residential houses; and were in fact close to levels measured at a local traffic intersection in Tainan, Taiwan, and those in a graphite-electrode producing plant during the graphitization process. It is obvious that such substantially high concentrations of PAHs and TSP constitute a potential health hazard to people working in or visiting the temple.