Greenhouse effect of NOX

Through various processes the nitrogen oxides (NO_X) interact with trace gases in the troposphere and stratosphere which do absorb in the spectral range relevant to the greenhouse effect (infrared wavelengths). The net effect is an enhancement of the greenhouse effect. The catalytic role of NO_X in the production of tropospheric ozone provides the most prominent contribution. The global waming potential is estimated as GWP (NO_X = 30 – 33 and 7 – 10 for the respective time horizons of 20 and 100 years, and is thereby comparable to that of methane. NO_X emissions in rural areas of anthropogenically influenced regions, or those in the vicinity of the txopopause caused by air traffic, cause the greenhouse effectivity to be substantially more intense. We estimate an additional 5–23 % for Germany’s contribution to the anthropogenic greenhouse effect as a result of the indirect greenhouse effects stemming from NO_X. Furthermore, a small and still inaccurately defined amount of the deposited NO_X which has primarily been converted into nitrates is again released from the soil into the atmosphere in the form of the long-lived greenhouse gas nitrous oxide (N₂O). Thus, anthropogenically induced NO_X emissions contribute to enhanced greenhouse effect and to stratospheric ozone depletion in the time scale of more than a century.     

Persistent organochlorine pollutants in human serum of 50-65 years old women in the Flanders Environmental and Health Study (FLEHS). Part 2: Correlations among PCBs,PCDD/PCDFs and the use of predictive markers

In 1999, the FLEHS was set by the Flemish Ministry of Health, Belgium to assess pollutant concentrations and related health effect biomarkers in humans living in Flanders. Concentrations of selected organochlorine pesticides, polychlorinated biphenyls (PCB) and polychlorinated dibenzo-p-dioxins (PCDD) and furans (PCDF) were measured by gas chromatography-mass spectrometry and Chemical-Activated LUciferase gene eXpression (CALUX) bioassay in 47 serum pools of 200 women between 50 and 65 years living in two areas of Flanders. Correlation between TEQ values of different groups of compounds were computed in these pool results and it was found that total toxic equivalencies (TEQs) correlated well with the values of the groups of contributing compounds: mono-ortho PCBs (r = 0.77), non-ortho PCBs (r = 0.65) and PCDD/Fs (r = 0.88). The total TEQ was lower correlated to the CALUX-TEQ (r = 0.57). When calculating associations between those classes of compounds in the two studied regions separately, they were all higher correlated in the urban area compared to the more rural region. High correlation coefficients (r > 0.80) were also calculated between individual compounds and groups of compounds. It was suggested that in this studied background-exposed population, some compounds could be good predictors for a group: e.g. PCB 153 for indicator and total PCBs, PCB 118 for total PCB TEQ, PCB 156 for mono-ortho PCB-TEQs and total TEQ, 2,3,4,7,8-P5CDF for PCDD/F TEQs and total TEQs. This means that in pooled serum samples correlations between persistent organochlorine compounds are as strong as for individual POP measurements observed in earlier studies.     

Forest ecosystems and the changing patterns of nitrogen input and acid deposition today and in the future based on a scenario

A global assessment of the impact of the anthropogenic perturbation of the nitrogen and sulfur cycles on forest ecosystems is carried out for both the present-day [1980-1990] and for a projection into the future [2040-2050] under a scenario of economic development which represents a medium path of development according to expert guess [IPCC IS92a]. Results show that forest soils will receive considerably increasing loads of nitrogen and acid deposition and that deposition patterns are likely to change. The regions which are most prone to depletion of soils buffering capacity and supercritical nitrogen deposition are identified in the subtropical and tropical regions of South America and Southeast Asia apart from the well known 'hotspots' North-Eastern America and Central Europe. The forest areas likely to meet these two risks are still a minor fraction of the global forest ecosystems, though. But the bias between eutrophication and acidification will become greater and an enhanced growth triggered by the fertilizing effects of increasing nitrogen input cannot be balanced by the forest soils nutrient pools. Results show increasing loads into forest ecosystems which are likely to account for 46% higher acid loads and 36% higher nitrogen loads in relation to the 1980-1990 situation. Global background deposition of up to 5 kg N ha-1 a-1 will be exceeded at more than 25% of global forest ecosystems and at more than 50% of forest ecosystems on acid sensitive soils. More than 33% of forest ecosystems on acid sensitive soils will receive acid loads which exceeds their buffering capacity. About 25% of forest areas with exceeded acid loads will receive critical nitrogen loads.     

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