Particulate barium fluxes on the continental margin: a study from the Alboran Sea (Western Mediterranean)

Particulate biogenic barium (bio-Ba) fluxes obtained from three instrumented arrays moored in the Alboran Sea, the westernmost basin in the Mediterranean Sea, are presented in this study. The mooring lines were deployed over almost 1 year, from July 1997 to May 1998, and were equipped with sediment traps at 500–700 m depth, 1000–1200 m depth and 30 m above the seafloor (1000–2200 m). The results obtained support the growing body of evidence that the relationship between particulate bio-Ba and Corg throughout the water column in margin systems is clearly different from this relation in the open ocean. In the Alboran Sea, the annual averaged bio-Ba fluxes range from 0.39 to 1.07 μmol m⁻² day⁻¹, with mean concentrations of 1.31–1.69 μmol g⁻¹ and bio-Ba/Corg ratios lower than in the open ocean. The low bio-Ba values obtained also indicate that calculating bio-Ba is extremely sensitive to the detrital Ba/Al ratio of each sample. The lithogenic Ba fraction in the Alboran Sea continental margin area contributes between 24% and 85% of the total Ba. Increased bio-Ba export efficiency was observed after periods of high primary productivity and suggests that the processes limiting the bio-Ba formation in the study area relate to settling dynamics of organic matter aggregates. Furthermore, the ballasting effect of the abundant lithogenic and carbonate particles may limit decomposition of organic matter aggregates and enhance the transfer of particles rich in Corg and relatively poor in bio-Ba to the deep seafloor. Lateral input of freshly sedimented biogenic material, including particulate bio-Ba, has been observed on the lower continental slope in the western Alboran Sea. These observations emphasize that the use of the bio-Ba as a proxy of export productivity from the surface ocean must be used cautiously in highly dynamic environments such as those in the Alboran Sea.     

The influence of topographic variables on treeline trees under different environmental conditions

Aiming to analyze the site conditions of treeline trees at the highest elevations, we investigated 360 km of treelines in the Upper Valtellina, Italian Alps. We analyzed approximately five trees per km and determined the environmental factors limiting treeline elevation by distinguishing between geomorphologic constraints (mean elevation 2355 m), climatic constraints (2530 m), and human impacts (2335 m). Up to 82% of the 1814 analyzed treeline trees were influenced by geomorphological constraints, whereas human impacts influenced only 3% of the trees. Climatic treelines (15% of trees) were most common in the western sector. Moreover we analyzed the frequency distributions of elevation, slope, and aspect. Elevation was the most important variable that was also strongly associated with climatic treelines. The slope variable was more strongly associated with treelines limited by geomorphology than by climate. By reconstructing the altitudinal dynamics at the Mt. Confinale study site, we found rates of an ongoing treeline upward shift of up to 2.6 m/y in the period 2000–2009. Our results indicate that climatic conditions related to the ongoing air temperature rise in this region will likely enhance the treeline shift, especially at high elevations (>2400 m a.s.l.) and on non-extreme slopes (<45°).     

Novel aryl polycyclic aromatic hydrocarbons: Phenylphenanthrene and phenylanthracene identification, occurrence and distribution in sedimentary rocks

Numerous reports have recognised the presence of compounds with molecular weight 254 a.m.u. in aromatic fractions. However, their unequivocal identification has not been achieved due to a lack of reference substances. In geological samples, such m/z 254 compounds could potentially be represented by a number of structural isomers of binaphthyl, phenylphenanthrene, phenylanthracene and indenofluorene with each compound type possessing several positional isomers. In this work, all these m/z 254 compounds, with the exception of the tentatively recognised indenofluorenes, have been unequivocally identified in sedimentary rocks for the first time. Comparison of the mass spectra and the gas chromatography (GC) retention times of synthesised standards with the natural compounds in rocks shows that the major components of aromatic fractions are phenylphenanthrene isomers and, to a lesser extent, binaphthyls and 9-phenylanthracene. The elution sequence expressed as standard retention indices of all these m/z 254 isomers were determined by using high resolution capillary GC with three stationary phases: 5%, 35% and 50% (mole fraction) phenyl substituted methylpolysiloxane on HP-5MS, DB-35MS and DB-17MS columns, respectively. A survey of more than 350 sedimentary rock samples of varying origins and maturity (R_r 0.3–1.4%) reveals that relative abundances of the m/z 254 isomers depend on the maturity of the organic matter. The isomers initially appear at the onset of oil generation (R_r > 0.5%) exclusively in diagenetically/catagenetically oxidised samples containing varying proportions of Types II and III kerogen. Interestingly, all five possible positional phenylphenanthrene isomers (including the most sterically hindered isomer 4-phenylphenanthrene) are present from the beginning of the oil generation window. Such a distribution suggests that low-regioselectivity reactions are likely to be involved in the formation. Interaction, during maturation, of phenyl radicals from primary cracking with aromatic moieties of more resistant terrigenic components of kerogen in an oxidising diagenetic realm is postulated to be responsible for the neoformation of phenylated aromatics in geological samples. Up to the final stages of oil generation, the evolution of the phenyl PAH distributions presumably involve 1,2-phenyl shift reactions and cyclisation, if allowed by the molecular geometry. A near thermodynamically-controlled distribution, with only 3- and 2-phenylphenanthrene and minor 2,2′-binaphthyl remaining, is approached when vitrinite reflectance reaches 1.2% (R_r). The three compounds seem to be persistent beyond the oil window as is suggested by their presence in hydrothermal oil formed at T > 300 °C.     

Comparison of linear reconstructions for second-order finite volume schemes on polyhedral grids

Improved and enhanced oil recovery methods require sophisticated simulation tools to predict the injected flow pass together with the chemical reactions inside it. One approach is application of higher-order numerical schemes to avoid excessive numerical diffusion that is very typical for transport processes. In this work, we provide a first step towards higher-order schemes applicable on general polyhedral and corner-point grids typically used in reservoir simulation. We compare three possible approaches of linear reconstruction and slope limiting techniques on a variety of different meshes in two and three spatial dimensions and discuss advantages and disadvantages.     

Geophysical exploration of Guajará, a prehistoric earth mound in Brazil

An interdisciplinary team studied Guajará, a prehistoric artificial mound in the Brazilian Amazon. The geophysical surveys and excavations were interactive;this interaction furnished more information than either geophysics or excavation alone could have provided. While seven different geophysical methods were applied, the magnetic survey reported here was particularly valuable. A detailed interpretation of this survey quantified the magnetic material in the mound, and this furnished an initial estimate of the number of cooking hearths in the mound. Ten test excavations were concentrated at magnetic anomalies. These excavations located cooking hearths and burial urns. A reevaluation of the magnetic survey was then done in order to refine the estimate of the number of hearths in the mound; this yielded an estimate of 2200 hearths. This allowed the population of the site to be approximated at 78–156 people. The geophysical survey and excavations also identified possible locations for subsequent broad‐area excavations. © 2003 Wiley Periodicals, Inc.     

Highlands management in a flood-prone watershed: Does reflexive reciprocity make a difference?

Poor levels of reciprocity (or “upstream/downstream” situations) are believed to discourage responsible actions and thus make sustainability harder to achieve. This paper presents a study that compares land use management resulting from concurrent reflexive reciprocal and nonreciprocal relationships in a Haitian watershed. The watershed is typically nonreciprocal in that flash floods and debris flows affecting the lowlands are thought to be initiated by upslope land management. It differs from conventional nonreciprocal cases in that the majority of people living in the lowlands own or otherwise manage upslope land. Concepts of reciprocity and self-interest indicate that downslope-residing land managers should implement more upland hazard-reduction conservation practices than upslope-residing land managers. This idea was tested using data on the number of soil conservation measures applied to upslope land parcels. The resulting multilevel model demonstrated that downslope households report employing more soil conservation measures in their upslope fields than upslope households. Additional communal actions to increase assurances of working in concert, however, are still needed to reduce disaster vulnerability.     

Human Response to Extreme Events: a review of three post-tsunami disaster case studies

Investigating survivors' behaviour prior to, during and after a disaster provides emergency management agencies with greater understanding of the complexities which influence public response. This information can then be used to develop better community-based disaster risk-reduction strategies. In this paper, we review three post-tsunami disaster case studies: the Indian Ocean tsunami (IOT) on 26 December 2004, the Java tsunami on 17 July 2006 and the South Pacific tsunami on 29 September 2009. The 2004 IOT and 2006 Java tsunami surveys involved delayed-response post-disaster research using video interviewing. The 2009 South Pacific tsunami entailed rapid-response post-disaster research using questionnaire interviews. We highlight the major outcomes of each case study and, based on these, make recommendations for improving tsunami education programs in Australia. These include educating the public about tsunami risk, natural warning signs of tsunamis and regionally specific behavioural response. To help facilitate improvements to future post-disaster research, discussion on survey-related issues from each case study is provided.     

L'organisation capitaliste du territoire et le problème du logement en Italie

The capitalistic organization of territory and the housing problem in Italy.This paper provides the first results of a research programme regarding the selective and spatially differentiated use of the Italian territory by private capital in the housing sector.According to the 1971 census, in Italy there were 63,8 million rooms for 53,2 million inhabitants. As regards the 1951 census the increase of rooms has been of 26,5 million, i.e. of 70.9%, as against an increase of 15,6% of the population. In this period the investment in dwelling-houses has represented about 30% of total fixed investments which is more than in the other E.E.C. countries.The Italian building stock (with a medium average of 1.2 rooms per inhabitant), is theoretically sufficient to satisfy the population needs. This ratio, however, drops to 1.06 if we exclude the 7.6 million rooms in non-inhabited houses (“holiday houses”, new unsold houses, abandoned homes because of emigration or because of their poor conditions).Moreover, more than one third of the Italian population lives in overcrowded conditions (less than one room per person) and poor standard houses are 40% of the total.This is not only due to the fact that public investments in the housing sector have been insignificant (6% in the last ten years), or to the unequal social distribution of revenue, but also, moreover, to the speculative character of the building activity.The economic analysis shows that between 1951 and 1971, in the expansive stages of housing production, net incomes of the building and land sector have increased more rapidly than the total earned incomes and that they have been higher than the amount of investments in the sector. So, building and land estate rent have been among the main components of the Italian capitalistic accumulation through the exporpriation of a prominent share of wages. At the same time, the ever increasing growth in housing prices both for sale and for rent has forbidden the fulfilment of the needs of the lower classes, extending in an abnormal way the production of luxury and “holiday houses” to satisfy the requirements of the higher classes. This is the cause of the above mentioned contradiction between the amount of the unused or subused building stock and the existence of a large number of sub-standard and/or overcrowded houses.This mechanism of accumulation-expropriation worked because of a specific spatial structure. Its main character consists in a strong geographical concentration of the basic activities and of the population. 53.3% of 1960–1971 housing production has concentrated in 4.7% of the Italian communes with more than 20,000 inhabitants.The analysis carried out on a stratified sample including 1,524 communes allowed us to reach the following results: 1. We find situations of greater unsatisfaction of the needs in the largest industrial metropolitan north-western areas and in the underdeveloped southern communes with strong emigrations. 2. We have had the highest offer for houses, as regards the needs, in the communes with less than 5,000 inhabitants, in the communes with less than 250,000 inhabitants, with prevalently tertiary functions, and in the districts where development is more equilibrated, from a territorial point of view (i.e.: north-eastern Italy). 3. The mechanism of accumulation-expropriation worked mainly in the industrial areas and it grows at the ever increasing growth of agglomerations and urban overcrowding, determined by strong migratory flows. 4. Building activity of tertiary communes has been led, mainly, by the higher-class expansion of consumptions. 5. The same kind of demand has given rise to the strong increase of “holiday houses” which interests large periurban, coastal and Alpine areas. 6. The housing sector becomes in this way a component of territorial disequilibriums, caused by the industrial and tertiary polarization and it is inclined to enlarge them by the artful increase of urban rent. 7. This use of territory has the aim to encourage incomes removal among different social classes and to contribute in this way, to the process of capitalistic accumulation. But, by doing this, it causes a kind of growth, in the housing sector, which is unable to satisfy lower-class needs for houses. 8. The attainment of this last purpose would, therefore, mean an efficient regional planning and the elimination of urban rent, conditions which are in opposition to the maintenance of the present economic and social structure of the Italian economy, of which speculative building and rent sectors are, nowadays, essential components.     

Women, science and identity: interviews with female physical geographers

Summary Interviews with female physical geographers show that although the significance of gender in influencing a woman's position and identity in physical geography is contested, gender still remains an important social relation that structures the personal relations, institutional practices and material outcomes of academic physical geography.