Measurement of urinary excretion of the benzene metabolites S -phenylmercapturic acid ( S -PMA) and trans , trans -muconic acid ( t , t -MA) has been proposed for assessing benzene exposure, in ...workplaces with relatively high benzene concentrations. Excretion
of S -PMA and t , t -MA in underground workers at an oil shale mine were compared with the excretion in workers engaged in various production
assignments aboveground. In addition, possible modifying effects of genetic polymorphisms in glutathione S-transferases T1 ( GSTT1 ), M1 ( GSTM1 ), and P1 ( GSTP1 ) on the excretion of S -PMA and t , t -MA were investigated. Fifty underground workers and 50 surface workers participated. Blood samples and three urine samples
were collected from each worker: ( a ) a preshift sample collected the morning after a weekend, ( b ) a postshift sample 1 collected after the first shift, and ( c ) a postshift sample 2 collected after the last shift of the week. Personal benzene exposure was 114 ± 35 μg/m 3 in surface workers ( n = 15) and 190 ± 50 μg/m 3 in underground workers ( n = 15) in measurements made prior to the study. We found t , t -MA excretion to be significantly higher in underground workers after the end of shifts 1 and 2 compared with the corresponding
surface workers. The same picture, although not significant, was seen for S -PMA excretion. Excretion of S -PMA and t , t -MA was found to increase significantly during the working week in underground workers but not in those employed on the surface.
Both t , t -MA and S -PMA excretion were significantly higher in smokers compared with nonsmokers. Subjects carrying the GSTT1 wild-type excreted higher concentrations of S -PMA than subjects carrying the null genotype, suggesting that it is a key enzyme in the glutathione conjugation that leads
to S -PMA. The results support the use of benzene metabolites as biomarkers for assessment of exposure at modest levels and warrant
for further investigations of health risks of occupational benzene exposure in shale oil mines.
Katabatic winds and piteraq storms van As, Dirk; Fausto, Robert S.; Steffen, Konrad ...
Geological Survey of Denmark and Greenland bulletin,
2014, Letnik:
31
Journal Article
Recenzirano
In 2007 the Programme for Monitoring the Greenland Ice Sheet (PROMICE) was initiated to observe and gain insight into the mass budget of Greenland ice masses. By means of in situ observations and ...remote sensing, PROMICE assesses how much mass is gained as snow accumulation on the surface versus how much is lost by iceberg calving and surface ablation (Ahlstrøm et al. 2008). A key element of PROMICE is a network of automatic weather stations (AWSs) designed to quantify components of the surface mass balance, including the energy exchanges contributing to surface ablation (Van As et al. 2013).
The use of these AWS observations is not limited to studies of ice-sheet mass balance. PROMICE contributes to CryoNet (www.globalcryospherewatch.org/cryonet), the core network of surface measurement sites of the World Meteorological Organization (WMO) Global Cryosphere Watch. By real-time delivery through WMO, PROMICE observations contribute to improve both operational forecasting and climate analysis in the data-sparse Arctic. The Greenlandic population, highly dependent on accurate forecasting of weather conditions, benefits directly from these real-time observations. For instance, extreme surface wind speeds are a high-risk element in Greenland. The third-highest wind speed observed at the surface of the Earth (93 m/s or 333 km/h), was recorded in a 8–9 March 1972 storm at Thule in North-West Greenland (Stansfield 1972).
In this paper, we discuss the extent to which the Greenland ice sheet generates its own near-surface wind field. We use PROMICE data to gain insight into the interaction between air temperature, radiation and gravity-driven katabatic winds. We focus on a particularly powerful spring storm in 2013 that contributed to a fatality on an ice-sheet ski traverse attempt (Linden 2013).
Eine Kombination von Pd‐ und Cu‐katalysierten Kupplungen macht die hier gezeigten Verbindungen, zwei „dreispeichige Halbräder“ und ein „vierspeichiges Dreiviertelrad“, zugänglich. Die Strukturen ...aller Verbindungen wurden durch Röntgenstrukturanalysen aufgeklärt.
