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Nitrous oxide (N2O) is a potent greenhouse gas stemming mainly from nitrogen (N)-fertilizer application. It is challenging to quantify N2O emissions from agroecosystems because of the dearth of measured data and high spatial variability of the emissions. The eco-hydrological model SWAT (Soil and Water Assessment Tool) simulates hydrological processes and N fluxes in a catchment. However, the routine for simulating N2O emissions is still missing in the SWAT model. A submodule was developed based on the outputs of the SWAT model to partition N2O from the simulated nitrification by applying a coefficient (K2) and also to isolate N2O from the simulated denitrification (N2O + N2) with a modified semi-empirical equation. The submodule was applied to quantify N2O emissions and N2O emission factors from selected crops in two agricultural catchments by using NH4NO3 fertilizer and the combination of organic N and NO3− fertilizer as N input data. The setup with the combination of organic N and NO3− fertilizer simulated lower N2O emissions than the setup with NH4NO3 fertilizer. When the water balance was simulated well (absolute percentage error 2O emissions was captured. More research to test the submodule with measured data is needed.

Protecting water bodies from eutrophication, ensuring long-term food security and shifting to a circular economy represent compelling objectives to phosphorus management strategies. This study determines how and to which extent the management of phosphorus in Austria can be optimized. A detailed national model, obtained for the year 2013 through Material Flow Analysis, represents the reference situation. Applicability and limitations are discussed for a range of actions aimed at reducing consumption, increasing recycling, and lowering emissions. The potential contribution of each field of action is quantified and compared using three indicators: Import dependency, Consumption of fossil-P fertilizers and Emissions to water bodies. Further, the uncertainty of this assessment is characterized and priorities for the upgrade of data collection are identified. Moreover, all the potential gains discussed in the article are applied to the reference situation to generate an ideal target model. The results show that in Austria a large scope for phosphorus stewardship exists. Strategies based exclusively either on recycling or on the decline of P consumption hold a similar potential to reduce import dependency by 50% each. An enhanced P recycling from meat and bone meal, sewage sludge and compost could replace the current use of fossil-P fertilizers by 70%. The target model, i.e. the maximum that could be achieved taking into account trade-offs between different actions, is characterized by an extremely low import dependency of 0.23kgPcap−1y−1 (2.2kgPcap−1y−1 in 2013), by a 28% decline of emissions to water bodies and by null consumption of fossil-P fertilizers. This case study shows the added value of using Material Flow Analysis as a basis to design sound management strategies. The systemic approach inherent to it allows performing a proper comparative assessment of different actions, identifying priorities, and visualizing a target model.

Wie viele andere L��nder Europas und der Welt ist ��sterreich in hohem Ma�� auf Importe angewiesen, um den hohen Phosphor bedarf des Lebensmittelproduktionssystems zu stillen. Als Rohstoff wird Phosphor (P) aus begrenzten und nicht-erneuerbaren Phosphaterzen gewonnen, deren Produktion auf wenige L��nder beschr��nkt ist. Aufgrund der gro��en wirtschaftlichen Bedeutung bzw. des zuk��nftigen Versorgungsrisikos hat die Europ��ische Kommission im Jahre 2014 Phosphaterz als kritischen Rohstoff definiert. Der P-Gebrauch weist in ��sterreich und in Europa mehrere Ineffizienzen und Verluste auf. Zudem ist P nicht nur eine essentielle Ressource, sondern auch ein Schadstoff in Wasserk��rpern, wo hohe P-Konzentrationen zu Eutrophierung f��hren k��nnen. Forschungsaktivit��ten sind erforderlich, um P-Fl����e und -Lager durch nat��rliche und anthropogene Prozesse zu verstehen. Deren Ziel ist es, Ma��nahmen zu identifizieren, die zur effizienteren Ressourcennutzung bzw. zu niedrigeren Emissionen und Verlusten und zur geringeren Importabh��ngigkeit f��hren k��nnen. Die Materialflussanalyse (MFA) ist eine geeignete Methodik f��r derartige Untersuchungen. Sie wurde h��ufig angewendet um meist statische P-Haushalte auf verschiedenen geographischen Ebenen zu darzustellen. Zeitliche Ver��nderungen wurden jedoch h��ufig vernachl��ssigt, obwohl sie relevante Informationen im Hinblick auf die Entwicklung von Managementstrategien und auf die Leistungskontrolle liefern k��nnen. In dieser Dissertation wird ein mehrj��hriges MFA-Modell entwickelt und untersucht, das dem ��sterreichischen P-Haushalt von 1990 bis 2011 entspricht. Die systematische Analyse dieses Modells zeigt, dass sogar in diesem vergleichsweise kurzen und stabilen Zeitraum P-Fl����e und -Lager erheblich ge��ndert wurden.Relevante Trends in Bezug auf Managementleistungen bzw. die Auswirkung von scheinbar nicht zusammenh ��ngenden gesetzlichen und wirtschaftlichen Entwicklungen auf P-Fl����e wurden identifiziert. Au��erdem hat die detaillierte Untersuchung der zeitlichen Muster zu Ergebnissen gef��hrt, die sehr relevant im Bereich Wasserg��te sind - speziell angesichts der Emissionen in die Gew��sser. Es wurde festgestellt, dass sich die Verminderung von PEmissionen ��ber Punktquellen in den 1990ern in geringeren Konzentrationen bei niedrigen Durchflussraten in der Donau umgehend widerspiegelte, aber nicht in geringeren Frachten. Die in dieser Dissertation aufgestellte und durch die Analyse gest��tzte Hypothese lautet: nur nachdem das gro��e Hochwasser im Jahre 2002 die Gew��ssersohle intensiv aufgerissen hatte und nachdem es das durch mehrj��hrige Retention akkumulierte P-Lager abgebaut hatte, spiegelte sich die geringere Verf��gbarkeit vom gel��sten Paus Punktquellen in verminderten Frachten wider. Es ist daher erforderlich, die verfl��chtenen Auswirkungen von anthropogenen Ma��nahmen und hydrologischen Prozessen in gro��en Fl����en zu betrachten, um die Leistung des Umweltmanagements angemessen zu interpretieren. Das MFA-Modell des ��sterreichischen P-Haushalts soll nicht nur angewendet werden, um die Entscheidunstr��ger ��ber den Status quo und die bestehenden Probleme zu informieren, sondern es soll auch als Grundlagef��rdie Begutachtung verschiedener L��sungsans��tze dienen.Verschiedene Massnahmen sind vorhanden, um das System zu optimieren. Das detaillierte System des MFA-Modells erm��glicht den Vergleich von den relativen Beitr��gen der verschiedenen Massnahmen, was behilflich bei der Festlegung von Priorit��ten ist. Die Ergebnisse zeigen, dass Recycling von Abfallstr��men und Verbrauchsminderung ein ��hnliches Potential zur Senkung der Importabh��ngigkeit aufweisen, obwohl letzteres von h��herer Unsichereit und von komplexeren Herausforderungen betroffen ist. Wenn s��mtliche Ma��nahmen umgesetzt w��rden und maximale Anstrengung unternommen w��rde, k��nnte ��sterreich P-Minerald��nger vollst��ndig ersetzen bzw. die Emissionen um 28% und die Importabh��ngigkeit um 89% reduzieren. Solche Ziele sollten als erreichbare Maximumwerte und nicht unbedingt als Optima angesehen werden, da diese Bewertung weder Kosten noch weitere Umweltaspekte ber��cksichtigt, die in weiteren Forschungsarbeiten erfasst werden m��ssen. Ferner wurde die Datenqualit��t durch ein Indikatorenset charakterisiert. Es wurde dargestellt, wie verschiedene Aspekte der Datenqualit��t sich im Laufe der Zeit ge��ndert haben, und wie die Ber��cksichtigung der Unsichereit unsere F��higkeit stark beeinflusst Fl����e und Lager zu ��berwachen. Das hat auch dazu beigetragen, die Verbesserung der Datenerhebung zu priorisieren. Abschlie��end stellt diese Dissertation die Machbarkeit und die mehrfachen Vorteile dar, die ein regionales auf mehrj��rige MFA gest��tztes N��hrstoffmanagement anbiet. Die Integrierung derartiger Materialbuchf��hrung in die regul��re Statistiken w��rde deshalb ��ffentliche Beh��rden unterst��tzen Governance-Strategien zu entwickeln, Zielsysteme zu definieren, Feedbacks und Gegenleistungen zwischen Ma��nahmen zu verstehen, Managementleistungen zu beobachten bzw. Datenerhebung zu priorisieren., Austria, like the rest of Europe and most of other world countries, relies heavily on imports to satisfy the high demand of phosphorus (P) of its food production system. P is obtained from phosphate rock, which is a finite and non-renewable resource confined in a handful of countries. Owing to the great economic importance of P and to future supply risk, in the year 2014 the European Commission included phosphate rock in its List of Critical Raw Materials. The domestic use of P in Austria and in the rest of Europe presents several inefficiencies and losses. Further, P is not only a fundamental resource but also a harmful pollutant in water bodies, where its excessive concentration can cause sever eutrophication problems. Research is needed to understand P flows and stocks through anthropogenic and natural compartments in order to identify where actions can be taken to increase use efficiency, to reduce losses and emissions and thus to lower import dependency. Material Flow Analysis (MFA) constitutes a suitable approach for such investigations and has been widely applied to describe mostly static P budgets at diverse geographical scales. Temporal dynamics have been however mostly neglected, although they can provide relevant information for the design of management strategies and for the monitoring of their performance. This Thesis presents a multiyear MFA model that represents the Austrian P budget from 1990 to 2011. The systematic analysis of this model reveals that even in this relatively short and stable period of time P flows and stocks have undergone significant changes. Relevant trends in management performance are identified as well as the impact of apparently unrelated regulatory or economic developments on P flows. Further, the investigation in detail of temporal patterns has led to findings highly relevant in the field of water quality and emissions to water bodies. It was found that the decline of P point discharges in the 1990s did immediately translate into lower concentrations at low flow conditions in the Danube, but not into lower loads. The hypothesis put forward in this Thesis and supported by the analyses is that only after the large flood in the year 2002 intensively scoured the river bed and depleted the in-stream P stock accumulated during years of net retention, the reduced availability of dissolved P primarily stemming from point discharges was reflected in lower loads. It is therefore necessary to consider more thoroughly the interweaving effects of anthropogenic measures and hydrological processes in large rivers, in order to properly interpret and assess the performance of environmental management. The MFA model of the Austrian P budget should not only be applied to inform policy makers on the status quo and on the existing problems, but also as a basis to provide a solid assessment of possible solutions and improvements. A wide range of different actions is available to optimize the system. The detailed system provided by the MFA model allows the comparison of the relative contribution of the measures, which helps in setting priorities. The results show that both recycling from waste streams and reduction of consumption hold similar potentials to decrease import dependency, although the latter are affected by higher uncertainty and more complex challenges. If the whole set of actions were implemented and a maximum effort of P governance were undertaken, Austria could fully replace the use of mineral fertilizers, reduce emissions to water bodies by 28% and its import dependency by 89%. These shall be considered maximum achievable targets, but are not necessarily optimal, since this assessment still does not include costs and other environmental aspects, which need to be included in future research. Moreover, this work has characterized data quality through a set of indicators, has assessed how different aspects of data quality have improved or changed over time, has shown to which extent the consideration of uncertainty influences the ability of monitoring flows and stocks and has contributed to prioritize the improvement of data collection schemes. In conclusion, this Thesis presents the feasibility and the manifold benefits provided by approaching regional nutrients management based on multiyear MFA. If public authorities integrated such an accounting scheme into their routine statistics and reporting, it could assist them in the design of governance strategies and target systems, in the understanding of feedbacks and trade-offs between measures, in the monitoring of their effectiveness, in getting feedbacks on data quality and on prioritizing data collection.