Merging of low-mass systems and the origin of the fundamental plane

We present the preliminary results of a study of how small stellar systems merge to form larger ones. As we display the families of galaxies in the μ_e - R_e plane (effective surface brightness versus effective radius) we realize that different morphological types occupy different loci, evidencing the different physical mechanisms operating in each family. As proposed by Capaccioli et al. (1992) this diagram is the logical equivalent of the HR diagram for stars. Here we take some initial steps in understanding of how we can establish the evolutionary tracks, solely due to dynamical processes, in the μ_e - R_e plane, ultimately making a dwarf elliptical to turn into a normal elliptical galaxy. This revised version was published online in August 2006 with corrections to the Cover Date.     

Using a groundwater quality negotiation support system to change land-use management near a drinking-water abstraction in the Netherlands

A negotiation support system (NSS) was developed to solve groundwater conflicts that arose during land-use management. It was set up in cooperation with the stakeholders involved to provide information on the impact of land use, e.g., agriculture, nature (forested areas), recreation, and urban areas, on the quality of both infiltrating and abstracted groundwater. This NSS combined simulation programs that calculate (1) the concentrations of nitrate in shallow groundwater for each land-use area and (2) the transport of nitrate in the groundwater-saturated zone. The user interface of the NSS enabled scenario analyses. The NSS was validated at a drinking-water abstraction near Holten (the Netherlands) using a spatial planning process aimed at sustainable land-use and groundwater-resource management. Two land-use scenarios were considered: a base scenario reflecting the autonomous development and an adapted land-use scenario. The calculated results for shallow groundwater provided an explicit spatial overview of the impact of historical land use and N application on the quality of abstracted groundwater as well as insight into the impact of changes in land use and N application. Visualization of the conflicting interests of agriculture and the drinking-water abstraction helped all stakeholders accept the necessary changes in land use identified by the adapted land-use scenario of the NSS. These changes were included in the preferred land-use management option in the regional planning process, which has since been formalized. The NSS provided system insight, scoping analyses, and education, in addition to generating quantitative information on the impact of land-use functions on groundwater quality.     

Response of littoral chironomid communities and organic matter to late glacial lake—level,vegetation and climate changes at Lago dell’Accesa (Tuscany,Italy)

This study focuses on the response of lacustrine littoral chironomid communities to late glacial changes in limnological, environmental and climate conditions in the Mediterranean context. Late glacial chironomid (Diptera: Chironomidae) assemblages, organic petrography and geochemistry were analysed in a sediment core from the littoral zone of Lago dell’Accesa (Tuscany, Italy), where the lake-level fluctuations and the vegetation history have been previously reconstructed. Comparison of the chironomid stratigraphy to other proxies (pollen assemblages, organic petrography and geochemistry, lake-level) and regional climate reconstruction suggested the predominant influence of lake-level changes on the littoral chironomid fauna. The main lowering events that occurred during the Oldest and the Younger Dryas were followed by higher proportions of taxa typical of littoral habitats. A complementary study of organic matter suggested the indirect impact of lake-level on the chironomids through changes in humic status and habitat characteristics, such as the type of substrate and aquatic macrophyte development. Several chironomid taxa, such as Glyptotendipes, Microtendipes and Cricotopus type patens, were identified as possible indicators of low lake-level in the late glacial records. Nevertheless, this study suggested that parallel analyses of organic matter and chironomid assemblages may be needed to circumvent misinterpretation of littoral chironomid assemblage stratigraphy. There was a weak response of the chironomid assemblages to small lake-level lowerings that corresponded to the Older Dryas and Preboreal oscillations. A higher level of determination, e.g. to the species group level, may be necessary to increase the sensibility of the indicators to lake-level changes.     

Soil contamination from urban and industrial activity: example of the mining district of Linares (southern Spain)

The Linares region (southern Spain) has been subjected to two important sources of pollution: the intensive mining works and the urban-industrial activity. To obtain a geochemical characterisation of the soil, 31 trace elements were analysed and 669 soil samples were collected. By means of clustering analysis, we identified groups of elements and grid squares in which relations could be established concerning soil lithology, urban and industrial activities and the degree of pollution impact; in addition, we were able to characterise the geochemical background of the study area. The multivariate study led us to identify four factors. Particularly important was factor 2, which represented the elements associated with mineral paragenesis (Cu, Pb, As, Co, Mn, Zn, Sn, Ba). This factor also contains elements related with an urban-industrial activity, such as Pb, Cu, Zn, As and Ba. Furthermore, we identified factor 4, associating Ni, V and Cr, and which is related to the use of fuels.     

Suitability analysis for sand and gravel extraction site location in the context of a sustainable development in the surroundings of Zaragoza (Spain)

Zaragoza city is located in the central Ebro Basin, in the Iberian Peninsula. The fluvial terraces formed by the Ebro River present a valuable resource of sand and gravel deposits. However, taking advantage of these available resources implies conflicts with other land use interests like urban and industrial development as well as agricultural use, which has also traditionally occupied the alluvial terraces. These deposits represent a substantial groundwater resource that should be preserved for future generations. The development of spatial decision support systems (SDSS) has greatly assisted efforts for solving land-use conflicts. These systems combine the benefits of geographic information systems (GIS) and decision support methodologies and are therefore suitable to manage sustainable development of urban areas. In this contribution, an extraction suitability map taking into consideration a variety of environmental criteria is created with the help of a SDSS. The method used is the analytical hierarchy process which is integrated in ArcGIS. Areas most suitable to sand and gravel extraction are located in the high terraces, and in those terraces covered by pediments where the thickness of resource is relatively high. These areas are far from valuable natural areas, outside areas most vulnerable to groundwater contamination, and beneath soils with poor irrigation characteristics.     

Impact of natural (waves and currents) and anthropogenic (trawl) resuspension on the export of particulate matter to the open ocean: Application to the Gulf of Lion (NW Mediterranean)

Modern sediment deposits on continental margins form a vast reservoir of particulate matter that is regularly affected by resuspension processes. Resuspension by bottom trawling on shelves with strong fishing activity can modify the scale of natural disturbance by waves and currents. Recent field data show that the impact of bottom trawls on fine sediment resuspension per unit surface is comparable with that of the largest storms.     

Effects of pollen leaching and microbial degradation on organic carbon and nutrient availability in lake water

Nutrient fluxes across terrestrial-aquatic boundaries and their subsequent integration into lake nutrient cycles are currently a major topic of aquatic research. Although pollen represents a good substrate for microorganisms, it has been neglected as a terrestrial source of organic matter in lakes. In laboratory experiments, we incubated pollen grains of Pinus sylvestris in water of lakes with different trophy and pH to estimate effects of pollen input and its subsequent microbial degradation on nutrient dynamics. In this ex situ experiment, we measured concentrations of organic carbon, phosphorus and nitrogen in the surrounding water as well as microbial dynamics (bacteria and fungal sporangia) at well-controlled conditions. Besides leaching, chemical and microbial decomposition of pollen was strongest within the first week of incubation. This led to a marked increase of soluble reactive phosphorus and total dissolved nitrogen (up to 0.04 and 1.5 mg L⁻¹, respectively, after 5 days of incubation) in the ambient water. In parallel, pollen grains were rapidly colonized by heterotrophic bacteria and aquatic fungi. Leaching and microbial degradation of pollen accounted for ≥80, ≥40, ≥50% for organic C, N and P, respectively, and did not significantly differ among water samples from the studied lakes. Thus, pollen introduces high amounts of bio-available terrestrial organic matter and nutrients into surface waters within a short time. A rough calculation on P input into oligotrophic Lake Stechlin indicates that pollen plays an important ecological role in nutrient cycling of temperate lakes. This requires further attention in aquatic ecology.     

Contrasting regional discharge evolutions in the Amazon basin (1974–2004)

Former hydrological studies in the Amazon Basin generally describe annual discharge variability on the main stem. However, the downstream Amazon River only represents the mean state of the Amazonian hydrological system. This study therefore uses a new data set including daily discharge in 18 sub-basins to analyze the variability of regional extremes in the Amazon basin, after recalling the diversity of the hydrological annual cycles within the Amazon basin. Several statistical tests are applied in order to detect trends and breaks in the time series. We show that during the 1974–2004 period, the stability of the mean discharge on the main stem in Óbidos is explained by opposite regional features that principally involve Andean rivers: a decrease in the low stage runoff, particularly important in the southern regions, and an increase in the high stage runoff in the northwestern region. Both features are observed from the beginning of the nineties. These features are also observed in smaller meridian sub-basins in Peru and Bolivia. Moreover we show that the changes in discharge extremes are related to the regional pluriannual rainfall variability and the associated atmospheric circulation as well as to tropical large-scale climatic indicators.     

Coseismic and post-seismic signatures of the Sumatra 2004 December and 2005 March earthquakes in GRACE satellite gravity

The GRACE satellite mission has been measuring the Earth's gravity field and its temporal variations since 2002 April. Although these variations are mainly due to mass transfer within the geofluid envelops, they also result from mass displacements associated with phenomena including glacial isostatic adjustment and earthquakes. However, these last contributions are difficult to isolate because of the presence of noise and of geofluid signals, and because of GRACE's coarse spatial resolution (>400 km half-wavelength). In this paper, we show that a wavelet analysis on the sphere helps to retrieve earthquake signatures from GRACE geoid products. Using a wavelet analysis of GRACE geoids products, we show that the geoid variations caused by the 2004 December ( M _w= 9.2) and 2005 March ( M _w= 8.7) Sumatra earthquakes can be detected. At GRACE resolution, the 2004 December earthquake produced a strong coseismic decrease of the gravity field in the Andaman Sea, followed by relaxation in the area affected by both the Andaman 2004 and the Nias 2005 earthquakes. We find two characteristic timescales for the relaxation, with a fast variation occurring in the vicinity of the Central Andaman ridge. We discuss our coseismic observations in terms of density changes of crustal and upper-mantle rocks, and of the vertical displacements in the Andaman Sea. We interpret the post-seismic signal in terms of the viscoelastic response of the Earth's mantle. The transient component of the relaxation may indicate the presence of hot, viscous material beneath the active Central Andaman Basin.