Einsatz der Hasse-Diagrammtechnik zur vergleichenden Bewertung von aquatischen Wirkungstests

An evaluation of pollutants depends on the ecotoxicological quality of the effect tests carried out. In this paper a compilation of aquatic tests is given independently on administration needs. The results are summarized in a table listing fields of application, importance for mathematical modelling and ecological relevance. The table includes 55 tests and 8 attributes characterizing each tests The interpretation of the results listed in this table is hardly feasible. An appropriate tool to rank the tests is the technique ofHasse-diagrams. Using this tool it can be deduced that no test fulfills all demands. There are six tests which are optimal with respect to applicability and mathematical modelling. However, they have no relevance for ecosystems. Only two tests are optimal with respect to ecotoxicology, There is still a gap between tests with a wide field of applications and those tests which are relevant with respect to ecotoxicology.     

Cytogenetic diagnoses after chorionic villus sampling are less reliable in very-high- or very-low-risk pregnancies

An increasing number of cytogenetic prenatal diagnoses are performed on chorionic villus samplings. The accuracy of this method is influenced by chromosomal mosaicism, mostly confined to direct preparation methods. Especially those investigators who have experienced false-negative and false-positive findings propagate the combined use of direct and culture methods. Yet large collaborative studies have shown that in approximately two-thirds of diagnostic cases only one procedure is applied. Moreover, the accuracy of a cytogenetic investigation depends not only on the ontogenetic origin of the tissues investigated, but also on interacting factors such as the ‘a priori risk’ and the ‘predictive value of a cytogenetic finding’. On this basis a differentiated prenatal diagnostic procedure is discussed, including either sole short-term culture (STC), combined STC and long-term culture (LTC), primary amniocentesis (AC), or primary percutaneous umbilical blood sampling (PUBS). The predictive value of the cytogenetic diagnosis from CVS varies significantly dependent on the a priori risk of a chromosome aberration and, in the case of an abnormal karyotype, on the specific chromosome involved. A non-mosaic and ‘non-lethal’ trisomy detected in STC is highly representative of the embryo/fetus, but there are exceptions of limited predictive value, e.g., trisomy 18. Guided by the strategy of an optional follow-up by LTC, AC, or PUBS in 1317 successive CV samplings, we are not aware of a false-negative diagnosis, but probably had one false-positive diagnosis: 47,XXY after STC; 46,XY after LTC. When referring to the rate of fetuses with an unbalanced karyotype expected in the different indication groups, a relative increase of false-positive findings in the very-low-risk group (maternal age ⩽35 years of age) and of false-negative findings in the very-high-risk group (abnormal ultrasonographic findings) of pregnant women when only performing CVS becomes obvious. Because of this dilemma, AC or—especially in the latter group—PUBS might be primarily offered to these indication groups instead of CVS.     

Nitrogen Oxide Emissions of Boilers in Finland

This article discusses nitrogen oxide emissions from various types of boilers in Finland. The boilers have been classified into 61 classes according to their size, combustion technique, and main fuel. A specific emission coefficient (ng NO₂/J = mg NO₂/MJ) for each class has been determined, based on literature surveys and actual measurements. The total NO_X emission has been calculated for each class, using the emission coefficient and energy statistics. The effect of various techniques for emission reduction has also been investigated. The development of NO_X emissions has been estimated for both the case where no preventing actions have been taken and for four defined cases where alternative reduction measures are assumed

The total NO_X emission from energy production in Finland was 107,000 tons NO₂ in 1987. Seventy-five percent of this amount originated in boilers larger than 1 MWfuel effect (input effect), and the rest in smaller boilers and industrial processes. The most important boiler classes from the NO_X emission’s point of view were coal-fired boilers, with an emission of approximately 38,000 tons NO₂, peat-fired boilers and boilers fired with a mixture of fuels, emitting approximately 12,000 tons NO₂ each.

By 2005, the total NO_X emission from energy production would increase 50 percent to approximately 160,000 tons if left uncontrolled. The emission level would be 140,000 tons if primary reduction techniques are applied, and 110,000 tons NO₂, if catalytic NO_X reduction devices are installed in boilers larger than 300 MW.