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See detailChamber-based continuous measurement of N2O fluxes in a winter wheat field: comparison of tillage treatments and identification of emission peak dynamic
Broux, François ULg; Theodorakopoulos, Nicolas; Heinesch, Bernard ULg et al

Scientific conference (2016, September 27)

Agriculture is the first anthropogenic source of N2O, notably through fertilized croplands. Though, few publications have studied through continuous measurement the N2O emissions in cultivated lands. We ... [more ▼]

Agriculture is the first anthropogenic source of N2O, notably through fertilized croplands. Though, few publications have studied through continuous measurement the N2O emissions in cultivated lands. We conducted this study to assess the effect of farming practices and climate on N2O emissions from a winter wheat crop. The experiment was held in an experimental field in the loamy region in Belgium from March 2016 till crop harvest in August 2016. The N2O fluxes are measured on two nearby parcels in a winter wheat field with restitution of the residues from previous crop. For the past 8 years, one parcel was subjected to a reduced tillage (RT, 10 cm depth) and the other one to a conventional tillage (CT, 25 cm depth). On each parcel, the N2O emissions were assessed with homemade automated closed chambers. Measurement continuity and good temporal resolution (one mean flux every 4 hours) of the system allowed a fine detection and quantification of the emission peaks which usually represent the major part of N2O fluxes. In addition to gas fluxes, soil water content at various depths and surface temperature were measured continuously. Soil samples were taken regularly to determine soil pH, soil organic carbon and nitrogen pools (total, NO3- and NH4+) and study microbial diversity and nitrification/denitrification gene expression. Measurements are still in progress. First results suggested that fluxes were about 3 times larger in the RT parcel than in the CT parcel. Several emissions peaks were observed during the measurement period. The peaks occurred after fertilization events and seemed to be triggered by an elevation of soil water content. A comparison of the emissions between RT and CT and a discussion on peak temporal dynamics, focusing on their intensity, duration and starting time will be presented. [less ▲]

Detailed reference viewed: 7 (0 ULg)
See detailMethylglyoxal in tumor-stroma interactions ?
Durieux, Florence ULg

Scientific conference (2016, May)

Detailed reference viewed: 10 (3 ULg)
See detailA history of mass transport complexes related to eruptions and earthquake shaking: the case of Lake Motosu (Japan).
Lamair, Laura ULg; Hubert, Aurelia ULg; El Ouahabi, Meriam ULg et al

Conference (2016, March 04)

The QuakeRecNankai project focuses on geological records of paleoearthquakes along the Nankai-Suruga subduction zone, south central Japan. In the framework of the project, we investigated the Fuji Five ... [more ▼]

The QuakeRecNankai project focuses on geological records of paleoearthquakes along the Nankai-Suruga subduction zone, south central Japan. In the framework of the project, we investigated the Fuji Five Lakes, located at the eastern end of the Nankai-Suruga Trough. Here, we present results from Lake Motosu, the deepest of the Fuji Five Lakes (max. depth 122 m), including seismic reflection profiles, gravity cores and preliminary results of 6.8 m long piston core. We identify mass transport deposits and turbidites possibly triggered by earthquakes. We study the lake sedimentary architecture and the Holocene sedimentation with a high resolution GEOPULSE pinger system. A seismic grid with total length of 39 km covered the lake. We identify a specific seismic horizon that may be related to the Aokigaraharamarubi lava flow (864 A.D.). Strong reflectors may also correlate with tephra layers from Oniwa-Okuniwa eruptions (620-790 A.D). In the western part of the lake, the seismic reflection profile reveals a change after the proposed Oniwa-Okuniwa eruptions in terms of volume and length of mass transport deposits. Large mass-transport deposits occurring before the eruptions are characterized by chaotic seismic facies. After the eruptions, the mass-transport deposits are much smaller and are characterized by transparent seismic facies attributed to turbiditic flow. Six gravity cores (max. 90cm long) provide samples of the lake bottom sediments. In these cores, turbidites and megaturbidites were identified based on facies analyses, combined with X-ray scanning, geophysical properties, grain-size analysis, mineralogy and XRF. During the period between the Oniwa-Okuniwa eruptions and the Aokigaraharamarubi lava flow (620-864 A.D), several lava flows occurred in the northern part of Mount Fuji and drastically modified the catchment of Lake Motosu. The decreasing of the size of catchment led to a decreasing of sedimentary yield in the lake. The change in the sedimentation rate could partly explain why we have a change in the type of mass transport deposit. Additionally, analyses were performed to define the minimum shaking intensity required to destabilize the slope. To assess slope stability, we investigated the clay content and the clay mineralogy of samples taken along the slope. In this presentation, we discuss the link between eruptions of Mount Fuji, decreasing of the size of the catchment, sedimentation rate and earthquake shaking. [less ▲]

Detailed reference viewed: 17 (2 ULg)
See detailA history of mass transport complexes related to earthquake shaking: the case of Lake Motosu (Japan).
Lamair, Laura ULg; Hubert, Aurelia ULg; Boes, Evelien et al

Poster (2016, January 27)

The QuakeRecNankai project focuses on geological records of paleoearthquakes along the Nankai-Suruga subduction zone, south central Japan. In the framework of the project, we investigated the Fuji Five ... [more ▼]

The QuakeRecNankai project focuses on geological records of paleoearthquakes along the Nankai-Suruga subduction zone, south central Japan. In the framework of the project, we investigated the Fuji Five Lakes, located at the eastern end of the Nankai-Suruga Trough. Here, we present results from Lake Motosu, the deepest of the Fuji Five Lakes (max. depth 122 m), including seismic reflection profiles and gravity cores. We identify mass transport deposits and turbidites possibly triggered by earthquakes. We study the lake sedimentary architecture and the Holocene sedimentation with a very high resolution GEOPULSE pinger system. A seismic grid with total length of 39 km covered the lake. We identify a specific seismic horizon that may be related to the Aokigaraharamarubi lava flow (864 A.D.). Strong reflectors may also correlate with tephra layers from Oniwa-Okuniwa eruptions (620-790 A.D). In the western part of the lake, the seismic reflection profile reveals a change after the proposed Oniwa-Okuniwa eruptions in terms of volume and length of mass transport deposits. Large mass-transport deposits occurring before the eruptions are characterized by chaotic seismic facies. After the eruptions, the mass-transport deposits are much smaller than previously and characterized by transparent seismic facies attributed to a turbiditic flow. Six gravity cores (max. 90cm) provide samples of the lake bottom sediments. In these cores, turbidites were identified based on facies analyses, combined with X-ray scanning, geophysical properties, grain-size analysis, mineralogy and XRF. An age-depth model was established based on radionuclide dating. We compare the timing of sedimentary events in Lake Motosu with a historical catalogue of natural hazards in the Fuji Five Lakes area, including historical records of megathrust earthquakes rupturing the Nankai subduction zone, the Sagami Trough and other earthquakes occurring along inland faults. Several analyses were performed to understand why we have a change in type of mass transport deposit after the eruptions and to define the minimum shaking intensity required to destabilize the slope. To assess slope stability, we investigated the clay content and the clay mineralogy of the slope. Spatial statistics was also performed in order to evaluate the degree of the slope and the accumulation of sediment. We suggest that the presence of a scoria layer might have contributed to slope destabilization. [less ▲]

Detailed reference viewed: 19 (1 ULg)