Global sensitivity analysis of a process-based model for ammonia emissions from manure storage and treatment structures

The development of process-based models to estimate ammonia emissions from animal feeding operations (AFOSs) is sought to replace costly and time-consuming direct measurements. Critical to process-based model development is conducting sensitivity analysis to determine the input parameters and their interactions that contribute most to the variance of the model output. Global and relative sensitivity analyses were applied to a process-based model for predicting ammonia emissions from the surface of anaerobic lagoons for treating and storing manure. The objectives were to compare global sensitivity analysis (GSA) to relative (local) sensitivity analysis (RSA) on a process-based model for ammonia emissions. Based on the first-order coefficient, both GSA and RSA showed the model input parameters in order of importance in process model for ammonia emissions from lagoon surfaces were: (i) pH, (ii) lagoon liquid temperature, (iii) wind speed above the lagoon surface, and (iv) the concentration of ammoniacal nitrogen in the lagoon. The GSA revealed that interactions between model parameters accounted for over two-thirds of the model variance, a result that cannot be achieved using traditional RSA. Also, the GSA showed that parameter interactions involving liquid pH had more impact on the model output variance than the single parameters: (i) temperature, (ii) wind speed, or (iii) total ammoniacal nitrogen. This study demonstrates that GSA provides a more complete analysis of model input parameters and their interactions on the model output compared to RSA. A comprehensive tutorial regarding the application of GSA to a process model is presented.     

Stra?enversiegelung in Deutschland und ihre Beinflussung der Umwelt im Vergleich mit anderen OECD-L?ndern

Zusammenfassung  Die durch die Fernstra?en versiegelte Fl?che in Deutschland betr?gt 0,47% der Oberfl?che, ohne die Seitenstreifen und Gemeindestra?en. Z?hlt man diese hinzu, so erh?ht sich der Wert auf 1,3%. In den dicht besiedelten Bundesl?ndern Hessen und Nordrhein-Westfalen erh?hen sich die Werte in Hessen auf 0,59 bzw. 1,59% und in NRW auf 0,68 bzw. 1,82%. In anderen OECD-L?ndern betragen die Prozents?tze des durch Fernstra?en versiegelten Bodens zwischen 0,2 und 3,0%. Bei diesem Vergleich liegt Deutschland an 5. Stelle hinter den Benelux-L?ndern und Japan. In der Verkehrsdichte (zugelassene Kraftfahrzeuge pro Stra?enkilometer) liegt Deutschland an 3. Stelle hinter Italien und Gro?britannien. Die Bodenversiegelung durch Stra?endecken sch?digt die Umwelt durch die Einbringung verkehrsbedingter Schadstoffe und St?rung des Grundwasserspiegels, aber noch mehr durch die Zerteilung und Zerst?rung von Biotopen. Online-First: 19. Mai 2000     

Verteilung und Abnahme von bodennahem Ozon in städtischen und ländlichen Regionen

The compilation of ozone data for the federal states of Hesse and Northrhine-Westphalia (NRW) in Germany indicated that the concentration of ozone level slightly decreased during the years 1990–1998. The average concentration of ozone over forest areas is significantly higher than over cities. Only the maximum figures in the years approached one another. However, values passing the legal thresholds (180 μg ozone/m³) were two to three-fold higher over forests than over cities. The ozone concentration in air is inversely proportional to the traffic density. It is suggested that the lower NOx concentration over the forest than over cities is involved in the maintenance of the higher ozone-concentration over forest areas. In the cities, the ozone is reduced by NO to almost zero at night, whereas it is reduced by only about 50% over forests with lower NO concentrations. This reduction is only partially compensated in connection with the photolysis of NO₂ and the subsequent oxidation of O₂ to O₃ during the day. The ozone situation is principally the same in the federal states of Hesse and Northrhine-Westphalia.     

NOx- und NO2-Konzentrationen

It has been confirmed that the NO_x-concentration in air is highest over industrial areas and that it decreases by more than 75%, parallel to traffic density, over urban areas as related to forested areas. A significant correlation excists between NO₂-concentration and the parameters of “traffic density,” followed by “road density” and “number of inhabitants/km²” in urban areas. No positive correlation was found with the number of “registered cars” and the parameters of “land use”. In forested areas, the traffic density correlated with the NO₂-concentration, but the correlation was not significant. The other parameters had no positive correlation with NO₂-concentration. In forest, urban- and industrial-areas, the NO_x-concentration in the air had a fairly constant ratio to traffic density.     

Verteilung und Abnahme von bodennahem Ozon in st?dtischen und l?ndlichen Regionen

Zusammenfassung  Eine Zusammenstellung der Ozon-Me?werte der Luftme?stationnetze in Hessen und NRW ergab für die Jahresmittelwerte von 1990–1998 im Durchschnitt eine schwache Abnahme der Ozonkonzentrationen. Dabei lagen die Jahresmittelwerte der Ozonkonzentrationen über Waldstationen doppelt so hoch wie über Stadtstationen. Die Ozonkonzentrationen verhalten sich im regionalen Vergleich umgekehrt proportional zur Verkehrsdichte. In der Zahl der überschreitungen der gesetzlich festgelegten Grenzwerte von ≥180 μg Ozon/m³ pro Jahr lagen die Waldstationen mit dem 2–3 fachen Wert über den Stadtstationen. Lediglich die j?hrlichen Maximalwerte der stündlich gemessenen Ozonwerte n?hern sich einander. Die hohen Ozonwerte über den Waldstationen stehen im Zusammenhang mit den niedrigen Konzentrationen von NOx. Nachts reduziert sich das Ozon über den Waldstationen durch Rückreaktion mit vergleichsweise geringen Konzentrationen von NO nur bis ca. 50%, w?hrend der Ozongehalt über Stadtstationen bis nahe Null absinkt. Dieser Vorgang über den Stadtstationen wird auch durch Photolyse des in hohen Konzentrationen vorliegenden NO₂ und die dadurch erfolgende erh?hte Bildung von Ozon w?hrend des Tages nicht wieder kompensiert. Für die hier dargestellten Ergebnisse gibt es prinzipiell keine Unterschiede zwischen den Ozonverh?ltnissen in Hessen und NRW.      

Phthalates and the aquatic environment: Part II The bioconcentration and depuration of di-2-ethylhexyl phthalate (DEHP) and di-isodecyl phthalate (DIDP) in mussels (Mytilus edulis)

Mussels ($\text{Mytilus edulis}$) were exposed to di-2-ethylhexyl phthalate (DEHP) and to di-isodecyl phthalate (DIDP) over a period of 28 days. The bioconcentration factor (BCF) as measured by ¹⁴C analysis, reached estimated plateau levels corresponding to mean BCF values of approximately 2500 and 3500 for the DEHP and DIDP respectively. The mussels were then held in clean seawater for a further 14 days and ¹⁴C analysis showed a depuration half-life of approximately 3.5 days for both phthalates. During the whole 42 days of the experiment general observations on the health of the animals showed no evidence of any adverse effects.