Toshio Kawaraya

Characteristics of particulates and gaseous pollutants in a highway tunnel

Characteristics of air pollutants in a highway tunnel were studied in Osaka, Japan. The size distributions and concentrations of elemental carbon (EC) and organic carbon (OC) were measured. The results demonstrated that EC was the predominant constituent of particulates in the tunnel, which accounted for 71% by mass of the particulate matter (PM) of less than 2 μm in aerodynamic diameter. EC concentration increased linearly with increase in diesel traffic volume and the coefficient of correlation was found to be at a significant level (r=0.93, p<0.001). In contrast, OC size distribution was bimodal with peaks in the size ranges of less than 1 and 2–10 μm and not clearly dependent on diesel traffic volume. For the gaseous matter, nitrogen monoxide (NO) was found to be the major component of NOx (over 90%) and its concentration was proportional to the traffic volume of diesel vehicles (r=0.82, p<0.001). The concentrations of carbon monoxide (CO) and carbon dioxide (CO2) in the tunnel were found, by multi-regression analysis, to be dependent on both diesel and gasoline-powered vehicles.

Determination of 3-nitrofluoranthene and 1-nitropyrene in suspended particulate matter by liquid chromatography with fluorescence detection

Abstract 3-Nitrofluoranthene and 1-nitropyrene in suspended particulate matter can be determined precisely by liquid chromatography with fluorescence detection (392 nm excitation, 502 nm emission). The nitro polynuclear aromatic hydrocarbons (nitro-PAHs) are reduced to the corresponding amino compounds with aqueous sodium hydrosulfide solution. Other nitro-PAHs do not interfere. Calibration graphs are linear at least over the range of 0.06–1.2 ng of nitro-PAH. Relative standard deviations (n = 10) are 3.4% and 3.9% for 1.2 ng of 3-nitrofluoranthene and 1-nitropyrene, respectively.

Pretreatment by yeast for determination of nickel and vanadium in bitumen-in-water emulsion by inductively coupled plasma atomic emission spectrometry

Abstract A pretreatment by yeast makes it possible to completely dissolve the bitumen-in-water with only concentrated HNO 3 . Concentrations of nickel and vanadium in the dissolved samples were determined by inductively coupled plasma atomic emission spectrometry. The average contents of nickel and vanadium in the ORIMULSION ™ were found to be 66.9 and 323 μg/g (reported content 320–340 μg/g), respectively. The method gave reproducible and accurate results.

A case study for wintertime observation of atmospheric particulates by an eye-safe laser radar.

Atmospheric particulates were monitored on a typical high concentration day in early winter in Osaka, Japan, using a compact and portable eye-safe laser radar system. The height of mixing layer was about 0.4 km at 8:00 and gradually increased to 0.8 km at 14:00. The development of the layer was in inverse proportion to the decrease of particulates near the ground surface. Analysis of particulates collected with high-volume air samplers showed that concentrations of elemental carbon (EC), lead and ammonium ion near the surface decreased significantly from morning to midday, while concentrations of sulfate, nitrate, sodium and calcium ions were almost constant. The results obtained in the preliminary study suggest that anthropogenic particulates such as EC and lead are on the rise with development of mixing layer from morning to midday.