Annotated record of the detailed examination of Mn deposits in a core from R/V Hakuho Maru Cruise KH-74-4 station

A sediment core obtained from the northeastern Philippine Sea Basin was analyzed for 232Th, 230Th, 226Ra and 210Pb. Three sheets of Ferro-manganese oxide in a matrix of red clay were included in the 73 m core. Although the concentration of 232Th of land origin is normal as compared with that of the usual red clay or of the sediment obtained at the neighboring station, the concentration of radiogenic 230Th is extremely low and does not decrease with increasing depth. The radioactivity of rather soluble 226Ra at the station is not less than that of 230Th in the surface sediment, showing a tendency different from that observed in usual cores. Some enrichment in the comparatively short-lived 210Pb activity relative to 226Ra activity was found in the top sediment and in the first ferro-manganese sheet at the station. If the excess 210Pb in the ferro-manganese sheet is not due to contamination of the surface sediment, lead should migrate through the sheet. These facts suggest that the core has not been accumulating during the past few hundred thousand years or more.

Downscaled land surface temperatures obtained by a particle smoothing approach, with links to NetCDF files

This dataset contains continuous time series of land surface temperature (LST) at spatial resolution of 300m around the 12 experimental sites of the PAGE21 project (grant agreement number 282700, funded by the EC seventh Framework Program theme FP7-ENV-2011). This dataset was produced from hourly LST time series at 25km scale, retrieved from SSM/I data (André et al., 2015, doi:10.1016/j.rse.2015.01.028) and downscaled to 300m using a dynamic model and a particle smoothing approach. This methodology is based on two main assumptions. First, LST spatial variability is mostly explained by land cover and soil hydric state. Second, LST is unique for a land cover class within the low resolution pixel. Given these hypotheses, this variable can be estimated using a land cover map and a physically based land surface model constrained with observations using a data assimilation process. This methodology described in Mechri et al. (2014, doi:10.1002/2013JD020354) was applied to the ORCHIDEE land surface model (Krinner et al., 2005, doi:10.1029/2003GB002199) to estimate prior values of each land cover class provided by the ESA CCI-Land Cover product (Bontemps et al., 2013) at 300m resolution . The assimilation process (particle smoother) consists in simulating ensemble of LST time series for each land cover class and for a large number of parameter sets. For each parameter set, the resulting temperatures are aggregated considering the grid fraction of each land cover and compared to the coarse observations. Miniminizing the distance between the aggregated model solutions and the observations allow us to select the simulated LST and the corresponding parameter sets which fit the observations most closely. The retained parameter sets are then duplicated and randomly perturbed before simulating the next time window. At the end, the most likely LST of each land cover class are estimated and used to reconstruct LST maps at 300m resolution using ESA CCI-Land Cover. The resulting temperature maps on which ice pixels were masked, are provided at daily time step during the nine-year analysis period (2000-2009).

(Table 1) Concentrations of CaCO3 and organic carbon, organic matter atomic C/N ratios and delta13C values of sediment samples from Site DSDP 594

CaCO3 and total organic carbon concentrations, organic matter C/N and carbon isotope ratios, and sediment accumulation rates in late Quaternary sediments from DSDP Site 594 provide information about glacial-interglacial variations in the delivery of organic matter to the Chatham Rise offshore of southeastern New Zealand. Low C/N ratios and nearly constant organic delta13C values of ?23? indicate that marine production dominates organic matter supply in both glacial and interglacial times during oxygen isotope stages 1 through 6 (0-140 ka) and 17 through 19 (660-790 ka). Increased organic carbon mass accumulation rates in isotope stages 2, 4, 6, and 18 record enhanced marine productivity during glacial maxima. Excursions of organic delta13C values to ca. ?29? in portions of isotope stage 2 suggest that the local concentration of dissolved CO2 was occasionally elevated during the last glacial maximum, probably as a result of short periods of lowered sea-surface temperature. Dilution of carbonates by clastic continental sediment generally increases at this location during glacial maxima, but enhanced delivery of land-derived organic matter does not accompany the increased accumulation of clastic sediments.

Organic d13C values, kerogen atomic C/N ratios and relative weights of some kerogen pyrolysis products of ODP Hole 112-682A (Table 1)

Carbon isotopic composition of predominantly marine kerogen in latest Oligocene mudstones of the Peru Margin ODP 682A Hole shows an about 3.5? increase with decreasing age. Py-GC and elemental (C=N ratio) analysis of the kerogen plus sulphur isotopic study together with earlier knowledge on geological setting and organic geochemistry results in a better understanding of depositionary environment and allows to separation of the influence of concentration of water dissolved carbon dioxide (ce) on kerogen delta13C from that of other factors (bacterial degradation, sea surface temperature, DIC delta13C, productivity, and admixture of land plant OM). Based on this analysis, the major part of the kerogen shift is considered as a result of the latest Oligocene decrease of marine photosynthetic carbon isotopic fractionation in the Peru Margin photic zone, which in turn possibly reflects a simultaneous drop in atmospheric CO2 level. Uncertainties in the evaluation of the factors affecting the marine photosynthetic carbon isotopic fractionation and the extent of ocean-atmosphere disequilibrium do not permit calculation of the decrease of the atmospheric CO2.

Table 1: Main characteristics of the BIOTA observatories included in this study & Table 3: Occurrence of termite taxa at the observatories

Termites are the most important soil ecosystem engineers of semi-arid and arid habitats. They enhance decomposition processes as well as the subsequent mineralisation of nutrients by bacteria and fungi. Through their construction of galleries, nests and mounds, they promote soil turnover and influence the distribution of nutrients and also alter texture and hydrological properties of soils, thereby affecting the heterogeneity of their ecosystem. The main aim of the present thesis was to define the impact of termites on ecosys-tem functioning in a semi-arid ecosystem. In a baseline study, I assessed the diversity of termite taxa in relation to the amount of precipitation, the vegetation patterns and the land use systems at several sites in Namibia. Subsequently, I focussed on a species that is highly abundant in many African savannas, the fungus growing and mound building species Macro-termes michaelseni (Sjöstedt, 1914). I asked how this species influences the spatial hetero-geneity of soil and vegetation patterns. From repeated samplings at 13 sites in Namibia, I obtained 17 termite taxa of 15 genera. While the type of land use seems to have a minor effect on the termite fauna, the mean annual precipitation explained 96% and the Simpson index of vascular plant diversity 81% of the variation in taxa diversity. The number of termite taxa increased with both of these explanation variables. In contrast to former studies on Macrotermes mounds in several regions of Africa that I reviewed, soil analyses from M. michaelseni mounds in the central Namibian savanna revealed that they contain much higher nitrogen contents when compared to their parent material. Further analyses revealed that nitrate forms a major component of the nitrogen content in termite mounds. As nitrate solves easily in water, evaporation processes are most probably responsible for the transport of solved nitrates to the mound surface and their accumulation there. The analysed mounds in central Namibia contained higher sand propor-tions compared to the mounds of the former studies. Through the higher percentage of coarse and middle sized pores, water moves more easily in sandy soils compared to more clayey soils. In consequence, evaporation-driven nitrate accumulation can occur in the studied mounds at high rates. ff...

Characteristics of soil profiles from the Ouémé Upper Catchment (HVO), Térou, Benin

Soil degradation threatens agricultural production and food security in Sub-Saharan Africa. In the coming decades, soil degradation, in particular soil erosion, will become worse through the expansion of agriculture into savannah and forest and changes in climate. This study aims to improve the understanding of how land use and climate change affect the hydrological cycle and soil erosion rates at the catchment scale. We used the semi-distributed, time-continuous erosion model SWAT (Soil Water Assessment Tool) to quantify runoff processes and sheet and rill erosion in the Upper Ouémé River catchment (14500 km**2, Central Benin) for the period 1998-2005. We could then evaluate a range of land use and climate change scenarios with the SWAT model for the period 2001-2050 using spatial data from the land use model CLUE-S and the regional climate model REMO. Field investigations were performed to parameterise a soil map, to measure suspended sediment concentrations for model calibration and validation and to characterise erosion forms, degraded agricultural fields and soil conservation practices. Modelling results reveal current "hotspots" of soil erosion in the north-western, eastern and north-eastern parts of the Upper Ouémé catchment. As a consequence of rapid expansion of agricultural areas triggered by high population growth (partially caused by migration) and resulting increases in surface runoff and topsoil erosion, the mean sediment yield in the Upper Ouémé River outlet is expected to increase by 42 to 95% by 2025, depending on the land use scenario. In contrast, changes in climate variables led to decreases in sediment yield of 5 to 14% in 2001-2025 and 17 to 24% in 2026-2050. Combined scenarios showed the dominance of land use change leading to changes in mean sediment yield of -2 to +31% in 2001-2025. Scenario results vary considerably within the catchment. Current "hotspots" of soil erosion will aggravate, and a new "hotspot" will appear in the southern part of the catchment. Although only small parts of the Upper Ouémé catchment belong to the most degraded zones in the country, sustainable soil and plant management practices should be promoted in the entire catchment. The results of this study can support planning of soil conservation activities in Benin.