Simulering af DOC og DON i indsatsområde "Søndersø" på Fyn: Endelig rapport for Arbejdspakke 6 i projektet "Regional Grundvandsbeskyttelse ved hjælp af optimerede Økologiske Dyrkningssystemer"

Der er gennemført en beregning af udvaskning af nitrat, ammonium, DOC og DON for en konventionel og en økologisk situation i et indsatsområde ved “Søndersø” på Fyn. Beregningerne er udført med DAISY-modellen, indeholdende et nyudviklet DOC/DON-modul og MIKE SHE-modellen. Modelopsætningen, der dækker et noget større område end selve indsatsområdet, baserer sig på den eksisterende arealanvendelse og landbrugssituation for en del af området, og ekstrapoleret i den nordvestlige del. Ekstrapolationen dækker kun en lille del af det faktiske indsatsområde. Modelopsætningerne bygger på tidligere modelleringsstudier i samme område. Koncentrationerne af DOC og DON er stort set ens i de to scenarier på grund af, at den styrende faktor er jordens organiske pulje. På grund af større forekomst af græsmarker i økologisk landbrug ville man forvente en opbygning af den organiske pulje, men DAISY-modellen synes at undervurdere denne faktor. Forskellen i DOC/DON-produktion mellem konventionelt og økologisk jordbrug forventes derfor også at være undervurderet. For at beskrive DOC/DON-dynamikken i grundvandet, er den udvaskede mængde opdelt i forskellige puljer, med forskellige C/N-forhold og nedbrydningstid. Mængden af uorganisk nitrat udvasket fra rodzonen er væsentligt lavere i indsatsområdet efter omlægning til økologisk brug, nemlig 29 kg N/ha i forhold til 70 kg N/ha i gennemsnit før omlægningen. Effekten af omlægningen er noget forsinket. Nitratkoncentrationen til dræn falder fra 13.2 kg nitrat-N/ha (2003-2012) i det konventionelle scenarie til 9.5 kg nitrat-N/ha i det økologiske scenarie, opgjort som gennemsnit for de første 10 år af omlægningen (samme klimaserie og periode). For koncentrationerne i det øverste grundvandsmagasin bliver koncentrationsændringerne først rigtigt synlige mod slutningen af simuleringsperioden, men ikke i alle beregningspunkter. I 2013 er forskellen mellem den gennemsnitlige nitratkoncentration i det konventionelle og økologiske scenarie 9 procent (af koncentrationen for det konventionelle scenarie med redoxzone og DOC-nedbrydning implementeret), men det skylles at kun en lille del af det øverste magasin har en alder på 0-10 år. Fortsættes beregningerne derfor i yderligere 30 år, vil den lavere udvaskning i det økologiske scenarie også slå væsentligt kraftigere igennem på grundvandskoncentrationerne. Men man kan altså ikke forvente en umiddelbar effekt af en dyrkningsomlægning på en nitrattruet grundvandsindvinding. Omkring 52 % af nitraten, der forlader rodzonen i indsatsområdet, reduceres i redoxzonen. Da dette gælder for begge scenarier, er der i de pågældende områder ingen effekt af omlægning. DOC-betinget denitrifikation har fjernet yderligere ca 6 % af nitraten i det konventionelle scenarie. Da den nedvaskede DOC-mængde er lille i beregningerne, kan dette tal være undervurderet, især i det økologiske scenarie. På den anden side er det antaget, at alt DOC-nedbrydning medvirker til denitrifikation, hvilket er en overvurdering. Forskellen mellem denne beregning og det økologiske scenarie er kun yderligere 4 procent i 2013 (konservativ transport og konventionelt scenarie = 100 %). I denne rapport er gjort en række simple antagelser om nedbrydning, nitrifikation, denitrifikation og sorption i grundvandszonen. Antagelserne fører til en udvikling i DOC og DON, der nogenlunde svarer til generelle observationer vedrørende koncentrationer og C/N-forhold, men der foreligger ikke måledata eller detailundersøgelser, der kan anvendes til en mere detaljeret parameterisering og procesforståelse. For at opnå en bedre forståelse af betydningen af DOC-produktion på denitrifikation, ikke mindst i økologisk produktion, kræves derfor yderligere undersøgelser

Perturbirana kutna gama-gama korelacija 208.00 - 59.54 keV u 237Np

The perturbed directional 208.00 - 59.54 keV gamma-gamma angular correlation was measured in 237Np. The static hyperfine coupling between the nuclear magnetic moment and the angular momentum of the electronic states was found present both in the liquid source and in the polycrystallinic source. The spin sequence for the 208.00 → 59.54 → O keV transition was confirmed to be 3/3, 5/2, 5/2 with the mixing ratio δ = + 0.145 for the E2 admixture in the preferably M1 transition. The agreement between directional correlation and internal conversion data was shown to be fairly good. The angular momentum J of the electronic states was determined for both sources : for the polycrystallinic source the J = 1 value gives the attenuation factor G22 (t)J-1 in good agreement with the experimental results, while for the liquid source, the best J value was shown to be J = 3/2. The J-dependent hyperfine structure constant a was determined for the polycrystalinic source as a/ħ = 83 ± 3 MHz and for the liquid source as a/ ħ = 44 ± 2 MHz. The average magnetic field at the place of 237Np nuclei was deduced for the polycrystallinic source H (O)J-1 = 54 ± 14 [kOe] and for the liquid source H (O)J-3/2 = 42 ± 12 [kOe].Mjerena j e perturbirana kutna gama-gama korelacija 208.00 -59.54 keV u 237Np. Pokazano j e da perturbacija ove korelacije za vrijeme života (T1/2 = 63 ns) medijalnog 59.54 keV stanja dolazi od magnetske hiperfine interakcije između magnetskog dipolnog momenta j ezgre i kutne količine gibanja elektronskih stanja za tekući i polikristaliničan izvor. Potvrđen je niz spinova 3/2, 5/2, 5/2 za prijelaz 208.00 → 59.54 → O keV. Omjer miješanja δ = + 0,145 za E 2 primjesu u 208.00 keV u uglavnom M 1 prijelazu je u vrlo dobrom slaganju sa mjerenjima konverzionih koeficijenata. Određena je kutna količina gibanja J = 1 elektronskih stanja za izvor u polikristalnom obliku i J = 3/2 za tekući izvor. Konstanta hiperfine interakcije a (zavisna o kutnoj količini gibanja elektronskih stanja) određena je za oba izvora (u jedinicama ħ): za polikristaliničan izvor a/ ħ = 83 ± 3 [MHz], a za tekući izvor a/ ħ = 44 ± 2 [MHz] . To omogućuje izračunavanje prosječnog magnetskog polja na mjestu jezgre za polikristaliničan izvor H (O)J-1 = 54 ± 14 [kOe] i za tekući izvor H (O)J-3/2 = 42 ± 12 [kOe]

Study of Deformation Effects in the Charged Particle Emission from 46Ti

The 46Ti compound nucleus, as populated by the fusion-evaporation reaction 27Al + 19F at the bombarding energy of 144 MeV, has been investigated by charged particle spectroscopy using the multidetector array ICARE at the VIVITRON tandem facility of the IReS (Strasbourg). The light charged particles have been measured in coincidence with evaporation residues. The CACARIZO code, a Monte Carlo implementation of the statistical-model code CASCADE, has been used to calculate the spectral shapes of evaporated alpha-particles which are compared with the experimental spectra. This comparison indicates the possible signature of large deformations of the compound nucleus.Comment: 6 pages, 4 figures, Proceedings od the Zakopane 20004 Symposium, to be published in Acta Phys. Pol. B36 (2005

Long-term trends in yield variance of temperate managed grassland

The management of climate-resilient grassland systems is important for stable livestock fodder production. In the face of climate change, maintaining productivity while minimizing yield variance of grassland systems is increasingly challenging. To achieve climate-resilient and stable productivity of grasslands, a better understanding of the climatic drivers of long-term trends in yield variance and its dependence on agronomic inputs is required. Based on the Park Grass Experiment at Rothamsted (UK), we report for the first time the long-term trends in yield variance of grassland (1965–2018) in plots given different fertilizer and lime applications, with contrasting productivity and plant species diversity. We implemented a statistical model that allowed yield variance to be determined independently of yield level. Environmental abiotic covariates were included in a novel criss-cross regression approach to determine climatic drivers of yield variance and its dependence on agronomic management. Our findings highlight that sufficient liming and moderate fertilization can reduce yield variance while maintaining productivity and limiting loss of plant species diversity. Plots receiving the highest rate of nitrogen fertilizer or farmyard manure had the highest yield but were also more responsive to environmental variability and had less plant species diversity. We identified the days of water stress from March to October and temperature from July to August as the two main climatic drivers, explaining approximately one-third of the observed yield variance. These drivers helped explain consistent unimodal trends in yield variance—with a peak in approximately 1995, after which variance declined. Here, for the first time, we provide a novel statistical framework and a unique long-term dataset for understanding the trends in yield variance of managed grassland. The application of the criss-cross regression approach in other long-term agro-ecological trials could help identify climatic drivers of production risk and to derive agronomic strategies for improving the climate resilience of cropping systems

GDR Feeding of the Highly-Deformed Band in 42Ca

The gamma-ray spectra from the decay of the GDR in the compound nucleus reaction 18O+28Si at bombarding energy of 105 MeV have been measured in an experiment using the EUROBALL IV and HECTOR arrays. The obtained experimental GDR strength function is highly fragmented, with a low energy (10 MeV) component, indicating a presence of a large deformation and Coriolis effects. In addition, the preferential feeding of the highly-deformed band in 42Ca by this GDR low energy component is observed.Comment: 6 pages, 2 figures, Proceedings of the Zakopane2004 Symposium, to be published in Acta Phys. Pol. B36 (2005

Strong Deformation Effects in Hot Rotating 46Ti

Exotic-deformation effects in 46Ti nucleus were investigated by analysing the high-energy gamma-ray and the alpha-particle energy spectra. One of the experiments was performed using the charged-particle multi-detector array ICARE together with a large volume (4"x4") BGO detector. The study focused on simultaneous measurement of light charged particles and gamma-rays in coincidence with the evaporation residues. The experimental data show a signature of very large deformations of the compound nucleus in the Jacobi transition region at the highest spins. These results are compared to data from previous experiments performed with the HECTOR array coupled to the EUROBALL array, where it was found that the GDR strength function is highly fragmented, strongly indicating a presence of nuclei with very large deformation.Comment: 10 pages, 6 figures, Proceedings of the Zakopane Conference on Nuclear Physics, to be published in Acta Phys. Pol. B (2007

A new Krakow scanning nuclear microprobe: performance tests and early application experienc

A new scanning nuclear microprobe (MP) with a short-length probe forming system was designed, installed and tested at the 3MV Van de Graaff accelerator in Krakow. The MP resolution of 3.3mm was reached for a 2.4 MeV proton beam in the high-current mode (≥100pA). The MP facility provides a local, non-destructive, quantitative elemental microanalysis using a Proton Induced X-ray Emission (PIXE) technique. As example of possible applications an analysis of a geological sample containing monazite crystals investigated by PIXE method is presented

High-spin states and band terminations in v 49

High-spin states in 49 V have been studied through the 28 Si(28 Si, α3p) reaction using the EUROBALL γ-ray detector array. The 49 V level scheme has been extended up to 13.1 MeV including 21 new states. Both negative and positive parity states have been interpreted in the framework of theShell Model. The 27/2− and the 31/2+ band termination states have been observed in agreement with theoretical predictions.Fil: Rodrigues Ferreira Maltez, Dario Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia Física (Centro Atómico Constituyentes). Proyecto Tandar; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Hojman, Daniel Leonardo. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia Física (Centro Atómico Constituyentes). Proyecto Tandar; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lenzi, Silvia M.. Istituto Nazionale Di Fisica Nucleare.; Italia. Università di Padova; ItaliaFil: Cardona, Maria Angelica. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia Física (Centro Atómico Constituyentes). Proyecto Tandar; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; ArgentinaFil: Fernea, Enrico. Università di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Axiotis, M.. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Beck, C.. Université de Strasbourg; Francia. Centre National de la Recherche Scientifique; FranciaFil: Bednarczyk, P.. Polish Academy of Sciences; ArgentinaFil: Bizzetti, P. G.. Università di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Bizzetti Sona, A. M.. Università di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Della Vedova, F.. Università di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Grebosz, J.. Polish Academy of Sciences; ArgentinaFil: Haas, F.. Université de Strasbourg; Francia. Centre National de la Recherche Scientifique; FranciaFil: Kmiecik, M.. Polish Academy of Sciences; ArgentinaFil: Maj, A.. Polish Academy of Sciences; ArgentinaFil: Męczyński, W.. Polish Academy of Sciences; ArgentinaFil: Napoli, D. R.. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Nespolo, M.. Università di Padova; Italia. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Papka, P.. Université de Strasbourg; Francia. Centre National de la Recherche Scientifique; FranciaFil: Sánchez i Zafra, A.. Université de Strasbourg; Francia. Centre National de la Recherche Scientifique; FranciaFil: Styczen, J.. Polish Academy of Sciences; ArgentinaFil: Thummerer, S.. Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung; AlemaniaFil: Ziębliński, M.. Polish Academy of Sciences; Argentin