Use of geoprocessing in the study of land degradation in urban environments: the case of the city of São Carlos,state of São Paulo,Brazil

This paper presents a methodology for the geological engineering survey of land degradation in urban environments using both remote sensing and geoprocessing tools. The area under study was the city of São Carlos, state of São Paulo, Brazil (urban and expansion area). The data presented here were obtained from earlier studies, photointerpretation and geological engineering mapping. The Envi 4.1 software package was used to prepare the digital orthophotos that served as a reference base for the information. Orthorectification of the Ikonos image (PSM, 1 m) was done and compared with other orthophotos from studies of environmental degradation in urban areas. The evolution of land degradation processes was analyzed based on the photointerpretation of aerial photographs taken on different dates and using Ikonos image. This study allowed to conclude that most of the degradation occurring in the city has been caused by unplanned land occupation, in disregard of environmental conditions, resulting in environmental degradation and thus impacting the quality of life of the urban population.     

Environmental history since 11,000 C yr B.P. of the northeastern Pampas, Argentina, from alluvial sequences of the Luján River

Sedimentological, malacological, and pollen analyses from ¹⁴C-dated alluvial sections from the Luján River provide a detailed record of environmental changes during the Holocene in the northeastern Pampas of Argentina. From 11,200 to 9000 ¹⁴C yr B.P., both sedimentary and biological components suggest that the depositional environment was eutrophic, alkaline, and freshwater to brackish shallow water bodies without significant water circulation. During this time, bioclastic sedimentation was dominant and the shallow water bodies reached maximum development as the climate became more humid, suggesting an increase in precipitation. Short-term fluctuations in climate during the last stage of this interval may have been sufficient to initiate changes in the water bodies, as reduction of the volume alternated with periods of flooding. The beginning of the evolution of shallow swamps in the wide floodplain or huge wetlands was contemporaneous with a sea level lower than the present one. From 9000 and 7000 ¹⁴C yr B.P., mesotrophic, alkaline, brackish, probably anoxic swamps existed. Between 7000 and 3000 ¹⁴C yr B.P., anoxic calcareous swamps were formed, with subaerial exposure and development of the Puesto Berrondo Soil (3500-2900 ¹⁴C yr B.P.). A trend to a reduction of water bodies is recorded from 9000 to ca. 3000 ¹⁴C yr B.P., with a significant reduction after ca. 7000 ¹⁴C yr B.P. A shift to subhumid-dry climate after 7000 ¹⁴C yr B.P. appears to be the main cause. During this time, an additional external forcing toward higher groundwater levels was caused by Holocene marine transgression causing changes in the water bodies levels. The climate became drier during the late Holocene (ca. 3000 yr B.P.), when clastic sedimentation increased, under subhumid-dry conditions. Flood events increased in frequency during this time. From ca. A.D. 1790 to present, the pollen record reflects widespread disturbance of the vegetation during the European settlement.     

Quaternary and extant euryhaline Lamprothamnium Groves (Charales) from Australia: Gyrogonite morphology and paleolimnological significance

Charophytes are very common in Australian modern and Quaternary waterbodies, and are quite commonly incorrectly reported as “Chara” sp. or Lamprothamnium papulosum (Wallroth) Groves. This paper is the first attempt at the identification of the widespread euryhaline genus Lamprothamnium in Australia, and its use as a paleoenvironmental indicator. Lamprothamnium is distributed worldwide in all continents, except north and central America. The Australian environment, characterized by increasing aridity during the last 500 ka, has an abundance of saline lakes. We sampled 30 modern lakes and identified extant Lamprothamnium macropogon (A. Braun) Ophel and Lamprothamnium succinctum (A. Braun in Ascherson) Wood. Fossil gyrogonites, from lacustrine sediments ∼65 ka old from Madigan Gulf, Lake Eyre, were identified as Lamprothamnium williamsii sp. nov. We applied statistical analysis (analysis of variance, ANOVA) to the morphometry of the gyrogonites from one fossil and three living Lamprothamnium populations. The ANOVA test suggests all the populations are different, including two separate populations of extant L. macropogon, interpreted in this case as the expression of ecophenotypic variability. Lamprothamnium is a useful paleoenvironmental indicator because it indicates a non-marine environment with varying salinity ranging from fresh (usually 2–3 g l⁻¹) to 70 g l⁻¹, and water bodies holding water for at least 70 consecutive days. Collectively, these parameters provide important information in the study of ephemeral habitats.     

Cyclostratigraphy and high-frequency carbon isotope fluctuations in Upper Cretaceous shallow-water carbonates, southern Italy

Abstract A detailed carbon isotope study has been carried out on a Santonian (Upper Cretaceous) carbonate platform succession that crops out at Monte Sant'Erasmo (southern Italy). Previous centimetre‐scale studies on this succession have shown that high‐frequency eustatic changes, resulting from the Earth's orbital fluctuations, controlled the hierarchical organization of the depositional and early diagenetic features in elementary cycles, bundles (groups of three to five elementary cycles) and superbundles (groups of three or four bundles). The elementary cycles, which correspond to single beds, suggest a control caused by Earth's precession; the bundles and superbundles record the short (≈ 100 kyr) and long (≈ 400 kyr) eccentricity periodicity respectively. The δ¹³C signal of the Monte Sant'Erasmo succession is cyclic in nature and may be considered to be a reliable proxy for the sedimentary evolution (and related sea‐level history) of the analysed sequence. The carbon isotope cyclicity is recorded at bundle and superbundle level, but it is not evident at the scale of the elementary cycles, at least with the sampling interval used in this study. Spectral analysis of the δ¹³C record shows two main peaks corresponding to the short‐ and long‐eccentricity periodicity, whereas the precession signal is not evident in the power spectrum. In addition, lithofacies analysis shows that, in each bundle (and superbundle), higher C isotope values occur in sediments characterized by marine cements, whereas lower values are normally found in more restricted deposits overprinted by early meteoric diagenesis. Early diagenesis, driven by periodic sea‐level fluctuations, developed in either shallow‐subtidal (marine diagenesis) or subaerial‐exposed (meteoric overprint) sedimentary environments and directly influenced the carbon isotope signature. As a consequence, the δ¹³C record at Monte Sant'Erasmo reflects high‐frequency climatic oscillations controlling both environmental and early diagenetic changes. The long‐term isotopic record is similar to that of contemporaneous pelagic sections in England and elsewhere in Italy. It is concluded that the δ¹³C signature of shallow‐water carbonates, such as those of Monte Sant'Erasmo, offers great potential for correlation with coeval sections, including those of the pelagic realm.     

A method for na-tech risk assessment as supporting tool for land use planning mitigation strategies

Hazardous industrial sites have always represented a threat for the community often provoking major accidents overcoming the boundaries of the plants and affecting the surrounding urban areas. If the industrial sites are located in natural hazard-prone areas, technological accidents may be triggered by natural events, generating so-called na-tech events which may modify and increase the impact and the overall damage in the areas around them. Nevertheless, natural and technological hazards are still treated as two separate issues, and up to now the methods for na-tech risk assessment have been developed mainly for specific natural hazards, generally restricted to some plant typologies and to the area of the plant itself. Based on a review of the current na-tech literature, this article illustrates a risk assessment method as a supporting tool for land use planning strategies aimed at reducing na-tech risk in urban areas. More specifically, a multi attribute decision-making method, combined with fuzzy techniques, has been developed. The method allows planners to take into account, according to different territorial units, all the individual na-tech risk factors, measured through both quantitative and qualitative parameters, while providing them with a na-tech risk index, useful to rank the territorial units and to single out the priority intervention areas. The method is designed to process information generally available about hazardous plants (safety reports), natural hazards (hazard maps) and features of urban systems mainly influencing their exposure and vulnerability to na-tech events (common statistical territorial data). Furthermore, the method implemented into a GIS framework should easily provide planners with comparable maps to figure out the hazard factors and the main territorial features influencing the exposure and vulnerability of urban systems to na-tech events. The method has been tested on a middle-sized Municipality in the Campania Region, identified as 2nd class seismic zone, according to the Ordinance 3274/2003, in which a LPG storage plant, classified as a plant with major accident potential by the Seveso II Directive (art. 9), is located just within the city core.     

The water balance of an Amazonian micro‐catchment: the effect of interannual variability of rainfall on hydrological behaviour

In humid tropical systems, the large intraseasonal and interannual variability of rainfall can significantly affect all components of the water balance. This variability and the lack of detailed hydrological and meteorological data in both temporal and spatial scales have created uncertainties regarding the closure of the water balance for the Amazon basin. Previous studies in Amazonian micro‐catchments suggested that both the unsaturated and groundwater system, which are not taken into consideration in basin‐wide water budgets published in the literature, play an important role in controlling the timing of runoff generation. In this paper, the components of the water balance and the variations in different storages within the system were examined using 3 years' data from a 6·58 km² micro‐catchment in central Amazonia. The role and relative importance of the various stores were examined. The results show a strong memory effect in the groundwater system that carries over seasonal climate anomalies from one year to the next and affects the hydrological response well beyond the time span of the anomaly. In addition, the deep unsaturated zone was found to play a key role in reducing most of the intraseasonal variability and also affected the groundwater recharge. This memory effect is crucial for sustaining streamflow and evaporation in years with rainfall deficiency. The memory effect caused by storage in the groundwater and unsaturated systems may also prevent the closure of annual large‐scale water balances, which assume that storage returns to a standard state each year. Copyright © 2007 John Wiley & Sons, Ltd.     

Geological and Isotopic Constraints on the Metallogenic Evolution of the Proterozoic Sediment-Hosted Pb-Zn (Ag) Deposits of Brazil

Integrated studies of seven Proterozoic sediment-hosted, Pb-Zn-Ag sulfide deposits of Brazil, permit the estimation of the age of the hosting sequence and the mineralization, the nature of the sulfur and metal sources, the temperature range of sulfide formation and the environment of deposition. These deposits can be classified into three groups, according to their ages. (a) Archean to Paleoproterozoic: the Boquira deposit, in Bahia state, consists of stratiform massive and disseminated sulfides hosted by parametamorphic sequences of grunnerite-cummingtonite+magnetite that represent a silicate facies of the Boquira Formation (BF). Lead isotope data of galena samples indicate a time span between 2.7 and 2.5 Ga for ore formation, in agreement with the stratigraphic position of the BF. The relatively heavy sulfur isotope compositions for the disseminated and stratiform sulfides (+8.3 to +12.8 ‰ CDT)suggest a sedimentary source for the sulfur. (b) Paleo to Mesoproterozoic: stratiform and stratabound sulfides in association with growth faults are present in the Canoas mine (Ribeira, in Paraná state) and in the Caboclo mineralization (Bahia state). They are hosted by calcsilicates and amphibolites in the Canoas deposit, whereas in the Caboclo area the mineralization is associated with hydrothermally altered dolarenites at the base of the 1.2 Ga Caboclo Formation. The interpreted Pb-Pb age of the Canoas mineralization is coeval with the 1.7 Ga host rocks. Sulfur isotopic data for Canoas sulfides (+1.2 to +16 ‰ CDT) suggest a sea water source for the sulfur. The range between −21.1 and +8.8 ‰ CDT for the Caboclo sulfides could suggest the action of bacterial reduction of seawater sulfates, but this interpretation is not conclusive. (c) Neoproterozoic: stratiform and stratabound sulfide deposits formed during the complex diagenetic history of the host carbonate rocks from the Morro Agudo (Bambui Group), Irecê and Nova Redenção (Una Group), yield heavy sulfur isotope values (+18.9 to +39.4 ‰ CDT). The uniform heavy isotope composition of the barites from these deposits (+25.1 to +40.9 ‰) reflect their origin from Neoproterozoic seawater sulfates. The late-stage, and most important, metallic concentrations represent sulfur scavenged from pre-existing sulfides or from direct reduction of evaporitic sulfate minerals. Lead isotope data from the Bambui Group suggest focused fluid circulation from diverse Proterozoic sediment sources, that probably was responsible for metal transport to the site of sulfide precipitation. (d) Late Proterozoic to Early Paleozoic: lead-zinc sulfides (+pyrite and chalcopyrite) of Santa Maria deposits, in Rio Grande do Sul, form the matrix of arkosic sandstones and conglomerates, and are closely associated with regional faults forming graben structures. Intermediate volcanic rocks are intercalated with the basal siliciclastic members. Lead isotope age of the mineralization (0.59 Ga) is coeval with the host rocks. Sulfur isotopic values between −3.6 and +4.1 are compatible with a deep source for the sulfur.Geological, petrographic and isotopic data of the deposits studied suggest that they were formed during periods of extensional tectonics. Growth faults or reactivated basement structures probably were responsible for localized circulation of metal-bearing fluids within the sedimentary sequences. Sulfides were formed by the reduction of sedimentary sulfates in most cases. Linear structures are important controls for sulfide concentration in these Proterozoic basins.     

Effects of offshore platforms on soft-bottom macro-benthic assemblages: a case study in a Mediterranean gas field

The exploitation of fossil fuels in the Mediterranean Sea will likely lead to an increase in the number of offshore platforms, a recognized threat for marine biodiversity. To date, in this basin, few attempts have been made to assess the impact of offshore gas and oil platforms on the biodiversity of benthic assemblages. Here, we adopted a structured experimental design coupled with high taxonomic resolution to outline putative effects of gas platforms on soft-bottom macrofauna assemblages in the North Ionian Sea. The analysis was based on a total of 20,295 specimens of 405 taxa, almost entirely identified at species level. Multivariate and univariate analyses showed idiosyncratic patterns of assemblage change with increasing distance from the platforms. Potential reasons underlying such inconsistency are analyzed and the view that structured experimental monitoring is a crucial tool to quantify the extent and magnitude of potential threats and to provide sound baseline information on biodiversity patterns is supported.     

Paradigm shifts in community ecology: Open versus closed units,challenges and limits of connectivity studies

Due to the presence of the complex life cycles involving a benthic adult and a pelagic larval phase, the study of benthic community dynamics cannot ignore investigations of the processes occurring in the water column. Current investigations focus mainly on larval dispersal from an evolutionary and a biogeographic perspective, taking into account also population connectivity, conservation planning and coastal management. In the present paper we underline the need to improve knowledge of the main traits of marine invertebrate life cycles, highlighting the limits and challenges of current approaches. Firstly, we summarized the changing approaches within community studies, following the paradigm shifts found in recent marine ecological research, from supply‐side ecology to connectivity, and involving the concepts of open and closed populations. Secondly, we analysed the main larval traits influencing dispersal, paying particular attention to pelagic larval duration in light of the few available data for connectivity studies. The difficulty in estimating many of the main traits of larval ecology make numerical simulation fundamental for a better understanding of the relationship between propagule dispersal and seawater dynamics, both being highly variable. We conclude that some essential biological information is still lacking for the proper integration of the modeling approaches. Thus it is necessary to further investigate the life‐cycle traits and physiological and ecological characteristics of each species, an approach known as autecology or natural history. All too frequently modern ecologists ignore such reductionist approaches, although they are essential for a full understanding of processes, such as connectivity and metapopulation dynamics.