High Concentrations of Atmospheric Isocyanic Acid (HNCO) Produced from Secondary Sources in China.

Isocyanic acid (HNCO) is a potentially toxic atmospheric pollutant, whose atmospheric concentrations are hypothesized to be linked to adverse health effects. An earlier model study estimated that concentrations of isocyanic acid in China are highest around the world. However, measurements of isocyanic acid in ambient air have not been available in China. Two field campaigns were conducted to measure isocyanic acid in ambient air using a high-resolution time-of-flight chemical ionization mass spectrometer (ToF-CIMS) in two different environments in China. The ranges of mixing ratios of isocyanic acid are from below the detection limit (18 pptv) to 2.8 ppbv (5 min average) with the average value of 0.46 ppbv at an urban site of Guangzhou in the Pearl River Delta (PRD) region in fall and from 0.02 to 2.2 ppbv with the average value of 0.37 ppbv at a rural site in the North China Plain (NCP) during wintertime, respectively. These concentrations are significantly higher than previous measurements in North America. The diurnal variations of isocyanic acid are very similar to secondary pollutants (e.g., ozone, formic acid, and nitric acid) in PRD, indicating that isocyanic acid is mainly produced by secondary formation. Both primary emissions and secondary formation account for isocyanic acid in the NCP. The lifetime of isocyanic acid in a lower atmosphere was estimated to be less than 1 day due to the high apparent loss rate caused by deposition at night in PRD. Based on the steady state analysis of isocyanic acid during the daytime, we show that amides are unlikely enough to explain the formation of isocyanic acid in Guangzhou, calling for additional precursors for isocyanic acid. Our measurements of isocyanic acid in two environments of China provide important constraints on the concentrations, sources, and sinks of this pollutant in the atmosphere.

Anatomical variation of the posterior lumbar tributaries of the left renal vein in retroperitoneoscopic left living donor nephrectomy.

OBJECTIVES: To increase awareness of the anatomical variation of the posterior lumbar tributaries of the left renal vein in retroperitoneoscopic left living donor nephrectomy. METHODS: A total of 61 cases of retroperitoneoscopic left living donor nephrectomy were carried out from March 2008 to June 2010. The anatomical variations of the posterior lumbar tributaries of the left renal vein in these patients were noted. RESULTS: According to the variation of posterior lumbar tributaries, there were seven types in total, including five main types (accounts for 95.1%, 58/61 cases) and the type of reno-hemi-azygo-lumbar trunk (AZV; accounts for 16.4%, 10/61 cases). According to the number of posterior lumbar tributaries, no lumbar vein covers accounted for 16.4% (10/61 cases), one lumbar vein accounted for 47.5% (29/61 cases), two lumbar veins accounted for 32.8% (20/61 cases) and three lumbar veins accounted 3.3% (2/61 cases). According to the operation time during the process of managing posterior lumbar veins, it was type 4 (AZV) on which the surgeon spent the most time (P<0.05), and type 5 (no lumbar vein) on which the surgeon spent the least time (P<0.05). CONCLUSIONS: This is the first report of the anatomical variation of the posterior lumbar tributaries of the left renal vein in retroperitoneal laparoscopic left living donor nephrectomy. Detailed knowledge of these anatomical variations will undoubtedly help surgeons to avoid the potential risk of vein damage during nephrectomy and to obtain a longer renal artery for the following renal transplantation.