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The stable carbon isotope compositions of tetrols, erythritol and threitol were determined by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Using four tetrols with various delta(13)C values derivatized by methylboronic acid, the carbon isotope analysis method achieved excellent reproducibility and high accuracy. There was no carbon isotopic fractionation during the derivatization processes. The differences in the carbon isotopic compositions of methylboronates between the measured and calculated ranged from -0.20 to 0.12 per thousand, within the specification of the GC/C/IRMS system. It was demonstrated that delta(13)C values of tetrols could be calculated by a simple mass balance equation between tetrols, methylboronic acid, and methylboronates. The analogous 2-methyltetrols, marker compounds of photooxidation products of atmospheric isoprene, should have similar behavior using the same derivatization reagent. This method may provide insight on sources and sinks of atmospheric isoprene.

Isoprene is one of the most important non-methane hydrocarbons (NMHCs) in the troposphere: it is a significant precursor of O(3) and it affects the oxidative state of the atmosphere. The diastereoisomeric 2-methyltetrols, 2-methylthreitol and 2-methylerythritol, are marker compounds of the photooxidation products of atmospheric isoprene. In order to obtain valuable information on the delta(13)C value of isoprene in the atmosphere, the stable carbon isotopic compositions of the 2-methyltetrols in ambient aerosols were investigated. The 2-methyltetrols were extracted from filter samples and derivatized with methylboronic acid, and the delta(13)C values of the methylboronate derivatives were determined by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). The delta(13)C values of the 2-methyltetrols were then calculated through a simple mass balance equation between the 2-methyltetrols, methylboronic acid and the methylboronates. The delta(13)C values of the 2-methyltetrols in aerosol samples collected at the Changbai Mountain Nature Reserves in eastern China were found to be -24.66 +/- 0.90 per thousand and -24.53 +/- 1.08 per thousand for 2-methylerythritol and 2-methylthreitol, respectively. Based on the measured isotopic composition of the 2-methyltetrols, the average delta(13)C value of atmospheric isoprene is inferred to be close to or slightly heavier than -24.66 per thousand at the collection site during the sampling period.

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Abstract. Prestressed concrete composite box-girder bridges with corrugated steel webs were introduced in China in the early 21st century. Now the number of this type of bridges under construction and completed has been more than forty, and China has become the second country where this type of bridges is most widely applied in bridge engineering in the world.This paper presents the efforts made to promote the application of one of the environment-friendly bridge structures, namely prestressed concrete composite box-girder bridges with corrugated steel webs in China to reduce the concrete consumption. The development characteristics and problems on which further studies would be needed with respect to this type of bridge structure in China are discussed.