Environmental issues in urban groundwater systems: a multidisciplinary study of the Paranhos and Salgueiros spring waters,Porto (NW Portugal)

This study presents the results of a multidisciplinary approach, using hydrogeochemical, isotopic and ecotoxicological analyses, performed to assess the nature and suitability for use of Paranhos and Salgueiros spring waters (Porto city, NW Portugal). Based on the surface activities located along the course of the springs, 23 water samples were collected. All the samples were analysed for major element concentrations. The isotopic techniques employed included δ²H, δ¹⁸O and ³H. Standard acute bioassays with Daphnia magna were also performed. The hydrogeochemical analyses showed a nitrate and sulphate-enriched composition for these groundwaters, resulting mainly from urban drainage and sewer leakage. In the ecotoxicological analyses, no significant mortality was observed in any of the tests performed. The results obtained in this study suggest that Porto urban groundwater could be suitable for irrigation uses.     

Changes in coronal condensations emission after solar bursts at microwaves

The amount of circular polarization of the total solar radio emission at 7 GHz present permanent changes after the occurrence of certain radio bursts associated with larger flares. For isolated S-components, associated with such flares the changes of the polarization degree _sranges between 0.004 to 0.1, and appears to be a function of the flare importance. A semi-qualitative interpretation associates _swith magnetic field reductions at the S-component, agreeing fairly well with a flare mechanism based on collisionless dissipation of magnetic energy, corresponding to energies in the range of 10³⁰ to 10³² ergs, assuming an average model for the coronal condensations.     

A Global Inventory of Burned Areas at 1 Km Resolution for the Year 2000 Derived from Spot Vegetation Data

Biomass burning constitutes a major contribution to global emissions of carbon dioxide, carbon monoxide, methane, greenhouse gases and aerosols. Furthermore, biomass burning has an impact on health, transport, the environment and land use. Vegetation fires are certainly not recent phenomena and the impacts are not always negative. However, evidence suggests that fires are becoming more frequent and there is a large increase in the number of fires being set by humans for a variety of reasons. Knowledge of the interactions and feedbacks between biomass burning, climate and carbon cycling is needed to help the prediction of climate change scenarios. To obtain this knowledge, the scientific community requires, in the first instance, information on the spatial and temporal distribution of biomass burning at the global scale. This paper presents an inventory of burned areas at monthly time periods for the year 2000 at a resolution of 1 kilometer (km) and is available to the scientific community at no cost. The burned area products have been derived from a single source of satellite-derived images, the SPOT VEGETATION S1 1 km product, using algorithms developed and calibrated at regional scales by a network of partners. In this paper, estimates of burned area, number of burn scars and average size of the burn scar are described for each month of the year 2000. The information is reported at the country level. This paper makes a significant contribution to understanding the effect of biomass burning on atmospheric chemistry and the storage and cycling of carbon by constraining one of the main parameters used in the calculation of gas emissions.     

Effects of topography on the curvature of fold-and-thrust belts during shortening of a 2-layer model of continental lithosphere

We have used analogue experiments to investigate the effects of surface topography on the curvature of fold-and-thrust belts, under conditions of (1) initial relief, but no erosion, and (2) no initial relief, but differential erosion, sedimentation and transport.In experiments where a 2-layer model lithosphere shortened and thickened in front of an advancing straight piston, the geometry of the developing thrust wedge was very sensitive to variations in surface topography. In models with an initially flat, horizontal surface, and in the absence of erosion and sedimentation, thrusts were straight, propagated forwards, and nucleated at buckle folds far in front of an advancing piston. Around an initial topographic high (plateau or cone), thrusts tended to be arcuate, forming salients towards the foreland. Initial plateaux and cones tended to behave rigidly, while arcuate thrust slices formed around them. To accommodate differential slip, transfer zones developed on both sides of initial highs. Fault blocks rotated about vertical axes and thrusts moved in oblique slip within transfer zones. In models with initially horizontal surfaces, which were subject to differential erosion, sedimentation and transport, thrusts initially were straight, but then progressively rotated around non-eroded, thickened and stronger areas. These worked as indenters, in front of which new thrusts nucleated at curved buckle folds. These thrusts were also curved, their apices being in front of the thickened, non-eroded areas.In nature, arcuate structural patterns are to be found around the Altiplano of the Central Andes and around the Tromen volcanic ridge in the Neuquén Basin of northern Patagonia. We infer that these areas behaved in quasi-rigid fashion, protected as they were by their high elevations, and that differential erosion at the scale of the entire Andes may have contributed to oroclinal bending.     

Policy Performance and Brownfield Redevelopment in Milwaukee,Wisconsin*

The redevelopment of brownfield sites has become a central focus of government efforts aimed at developing and revitalizing urban areas in the U.S. This article examines brownfield redevelopment efforts in Milwaukee County, Wisconsin, which gained momentum in the mid‐1990s, in order to determine how Milwaukee is performing in terms of redevelopment activities, what the effects of government support of such activities have been, and how performance outcomes are currently being measured. Through an examination of government data and interviews with key stakeholders, the Milwaukee case reveals that redevelopment is indeed progressing well as government becomes more effective at tackling the barriers to private‐sector redevelopment. However, progress in redeveloping brownfields is still being measured primarily in terms of economic development outcomes rather than in terms of the broader social, economic, and environmental objectives that both policy makers and private‐sector stakeholders associate with such redevelopment.     

Physical models of rifting and transform faulting, due to ridge push in a wedge-shaped oceanic lithosphere

By scaled physical modelling, we have investigated the mechanical response to gravitational forces in an oceanic lithosphere, overlying a less dense asthenosphere. In the models, an upper wedge-shaped layer of sand represented an oceanic lithosphere (0–35 Ma old, with a half-spreading velocity of 3 cm/yr), and a lower layer of polydimethylsiloxane (PDMS), mixed with dense wolframite powder, represented the asthenosphere. In the models, as in nature, isostatic compensation resulted in uplift of ridges and subsidence on their flanks. The resulting relief was responsible for ridge push. We tested two main configurations: straight ridges and offset ridges. In all the models, ridge push was sufficient to cause plate motion, underlying advection, and symmetrical rifting at the ridge axis. There was no need to impose plate motions through external pistons and motors. In models of straight ridges, the style of normal faults in the axial rift zone depended on the local thickness of the brittle sand layer. For thick layers, normal faults rafted out from the active zone of rifting, creating a fossil topography of tilted blocks, between faults dipping toward the ridge. In a model of an offset ridge, with thin lithosphere at the ridge crest and no embedded weakness, ridge push was responsible for a short transform fault, linking en-échelon rifts. In a similar model, but with thick lithosphere, an oblique rift formed at about 20° to the offset trace. We conclude that ridge push was not adequate to create an ideal transform fault. In a model of an offset ridge, with an embedded thin vertical layer of pure PDMS at 90° to the ridge, transform motion concentrated along this weak layer, and the resulting structural style was very similar to that in nature. On the basis of these results, we infer that, in nature, (1) ridge push can indeed drive plate motion, and (2) ridge push can drive strike-slip motion on transform faults, provided that these are weaker than the adjacent oceanic lithosphere and that they form early in the history of spreading.     

Influence of a Brazilian sewage outfall on the toxicity and contamination of adjacent sediments

The submarine sewage outfall of Santos (SSOS) is situated in the Santos Bay (São Paulo, Brazil) and is potentially a significant source of contaminants to the adjacent marine ecosystem. The present study aimed to assess the influence of SSOS on the sediment toxicity and contamination at Santos Bay. At the disposal site, sediments tended to be finer, organically richer and exhibited higher levels of surfactants and metals, sometimes exceeding the “Threshold Effect Level” values. The SSOS influence was more evident toward the East, where the sediments exhibited higher levels of TOC, total S and metals during the summer 2000 sampling campaign. Sediment toxicity to amphipods was consistently detected in four of the five stations studied. Amphipod survival tended to correlate negatively to Hg, total N and % mud. This work provides evidence that the SSOS discharge affects the quality of sediments from Santos Bay, and that control procedures are warranted.     

Microwave observations of the 4 January, 1973 solar eclipse

The eclipse was observed at two microwave frequencies, 7 GHz and 22.2 GHz, and has shown the presence of polarized regions, suggesting also excess of left-handed polarized radiation from the solar northern hemisphere. Difference in eclipsing times at the two frequencies for an active center near the limb is discussed.     

Multi-criteria analysis for the identification of waste disposal areas

The municipality of Cachoeiro de Itapemirim (ES) is currently the largest domestic producer and exporter of marble and granite in Brazil. The processing of the rock, especially the sawing results in a large volume of waste, including the abrasives used during sawing and the off-cut pieces. Presently these waste products are disposed of without proper environmental protection and cause pollution to surface water and groundwater resources, including silting, an increase in hardness and increased aluminium values in the groundwater. In order to minimize the harmful effects of these practices on the environment, a research project was undertaken to identify potential disposal sites for the generated waste. A multi-criteria approach was followed during which a database was compiled of all the companies generating waste products and also including a baseline environmental study of the region, integrated analysis (multi-criteria analysis) of the restriction factors and the preliminary identification of possible disposal sites. This revised version was published online in July 2006 with corrections to the Cover Date.     

2-D rotation behavior of a rigid ellipse in confined viscous simple shear: numerical experiments using FEM

The rotation behavior of rigid elliptical inclusions adherent to the viscous matrix in simple shear flow is investigated using a 2-D finite element numerical model. Several simulations were performed using different ratios (S) between shear zone width and inclusion's least principal axis. A computational strategy was devised to calculate pressure and viscous forces exerted on the inclusion and deduce its angular velocity. For large S values, results agree remarkably well with theoretical predictions, while for small S values results deviate significantly from theory but are in agreement with previous analogue experiments. The numerical model provided detailed and coherent information about the physical parameters involved in the process (e.g., pressure, strain rate and vorticity distributions within the model).