RESUMO
We conduct the first 4D-Var inversion of NH3 accounting for NH3 bi-directional flux, using CrIS satellite NH3 observations over Europe in 2016. We find posterior NH3 emissions peak more in springtime than prior emissions at continental to national scales, and annually they are generally smaller than the prior emissions over central Europe, but larger over most of the rest of Europe. Annual posterior anthropogenic NH3 emissions for 25 European Union members (EU25) are 25% higher than the prior emissions and very close (<2% difference) to other inventories. Our posterior annual anthropogenic emissions for EU25, the UK, the Netherlands, and Switzerland are generally 10%-20% smaller than when treating NH3 fluxes as uni-directional emissions, while the monthly regional difference can be up to 34% (Switzerland in July). Compared to monthly mean in-situ observations, our posterior NH3 emissions from both schemes generally improve the magnitude and seasonality of simulated surface NH3 and bulk NH x wet deposition throughout most of Europe, whereas evaluation against hourly measurements at a background site shows the bi-directional scheme better captures observed diurnal variability of surface NH3. This contrast highlights the need for accurately simulating diurnal variability of NH3 in assimilation of sun-synchronous observations and also the potential value of future geostationary satellite observations. Overall, our top-down ammonia emissions can help to examine the effectiveness of air pollution control policies to facilitate future air pollution management, as well as helping us understand the uncertainty in top-down NH3 emissions estimates associated with treatment of NH3 surface exchange.
RESUMO
This study aimed at statistically investigating the association between the internal exposure of children and young adults to uranium (U) and epidemiologically relevant external determinants of exposure. The investigation was performed with data from two studies within the framework of the German health-related environmental monitoring program: The German Environmental Survey for Children (GerES IV) conducted by the Federal Environment Agency (Umweltbundesamt) with data on 1,780 children 3-14 years of age and their home environment and the German Environmental Specimen Bank (ESB, section: human specimens) with data on 2,253 students 20-29 years of age. Both studies provided data on the U levels in human urine for all probands. GerES IV furthermore provided an extensive environmental and demographic database on, e.g., U levels in drinking water. The data from GerES IV and ESB were linked by GIS to spatially relevant exposure information, including background values of U in stream sediments and in upper and lower soils, U levels in mosses and particulate matter in the lower atmosphere, precipitation and elevation as well as forest density. Bivariate correlation analysis and two decision tree models showed moderate but significant associations between U in human urine and U levels in drinking water, stream sediments and upper and lower soils. Future investigations considering additional epidemiologically relevant data sets may differentiate the results. Furthermore, the sample design of future environmental epidemiology studies should take the spatial evaluation of the data into greater account.
