The South America VLF NETwork (SAVNET)

In this paper we present the South America VLF NETwork (SAVNET), a new observing facility at very low frequencies. It has been recently installed at different locations spread over Latin America, in Brazil, Peru and Argentina. It consists of a network of seven Very Low Frequency (VLF) receivers with the main scientific objective of monitoring the solar activity on short (minutes to hours) and long (years) time scales. Other objectives include a better understanding of the spatial structure of the South Atlantic Magnetic Anomaly, the study of atmospheric phenomena and the search for genuine seismic-electromagnetic effects. After discussing the scientific goals, the details of the installation are presented as well as the first results recently obtained.     

Polygonal terrains on Mars: A contribution to their geometric and topological characterization

Detailed examination of large extensions of polygonal terrains on the surface of Mars and extraction of some characteristic geometric and topological parameters is made possible by the application of image analysis methods to scenes of the Martian surface acquired from orbit. This is illustrated by the analysis of a set of diverse Martian networks, clearly visible in MOC/MGS images with high spatial resolution. It is shown that these networks present, in average, a hexagonal habit, and that they verify two classic laws relative to 2D random networks (those of Lewis and Aboav-Weaire). This research can, through the quantified analysis of the differences and similarities between networks, lead into a much better understanding of the origin and dynamics of this type of features.     

System boundary setting in life cycle assessment of biorefineries: a review

A growing interest for biorefineries has resulted in a subsequent increase in publication of lifecycle assessments (LCA) of such systems in later years. This study explores choices made in system boundary setting in LCAs of biorefinery systems. Based on a review of 38 case studies published in the scientific literature, the study aims to identify and discuss methodological differences and effects of these on overall results. The review shows that the definition of feedstock is of key importance for chosen system boundary settings. Direct inputs and agriculture activities are included in 80 % of the systems where feedstock is regarded as dedicated biomass, while omitted when defined as residue. Land conversion for provision of dedicated biomass, as well as use of agriculture/forest residues, results in impacts with direct connection to the investigated biorefinery system, motivating inclusion of these processes in the assessment. However, these aspects are considered in less than 40 and 30 % of systems using dedicated biomass and residues as feedstock, respectively. Indirect land use changes and ‘lost opportunities’ can be relevant to assess—independent of the type of feedstock used, particularly when using consequential modeling. Such indirect aspects are, however, not always addressed in a coherent manner. Finally, it is observed that the end-of-life stage of bio-materials/chemicals commonly is not captured within set system boundaries, generating comparative disadvantage for bio-based systems, when compared to fossil reference systems. In summary, it can be concluded that omitting key issues from the investigated system can reduce the relevance of gained results, as well as the possibilities for cross-study comparisons. This calls for further development and use of already existing guidelines in this field.     

Evaluation of the presence of major anionic surfactants in marine sediments

The contamination of aquatic environments has become the focus of increasing regulation and public concern due to their potential and unknown negative effects on the ecosystems. The present work develops a monitoring and statistical study, based on the analysis of variance test (ANOVA) and the multivariable analysis, both for insoluble soap and LAS in order to compare the behavior of different anionic surfactants in this environmental compartment. First, a novel and successfully validated methodology to analyze insoluble soap in these samples is developed. The matrix effect and the comparison of different extraction techniques were also performed. The optimized analytical methodologies were applied to 48 representative samples collected from the Almeria Coast (Spain) and then a statistical analysis to correlate anionic surfactant concentration and several variables associated with marine sediment samples was also developed. The results obtained showed relevant conclusions related to the environmental behavior of anionic surfactants in marine sediments.     

Geochemical characterization of heavy metal contaminated area using multivariate factorial kriging

This paper describes a geostatistical method, known as factorial kriging analysis, which is well suited for analyzing multivariate spatial information. The method involves multivariate variogram modeling, principal component analysis, and cokriging. It uses several separate correlation structures, each corresponding to a specific spatial scale, and yields a set of regionalized factors summarizing the main features of the data for each spatial scale. This method is applied to an area of high manganese-ore mining activity in Amapá State, North Brazil. Two scales of spatial variation (0.33 and 2.0 km) are identified and interpreted. The results indicate that, for the short-range structure, manganese, arsenic, iron, and cadmium are associated with human activities due to the mining work, while for the long-range structure, the high aluminum, selenium, copper, and lead concentrations, seem to be related to the natural environment. At each scale, the correlation structure is analyzed, and regionalized factors are estimated by cokriging and then mapped.     

Evaluating and classifying contaminated areas based on loss functions using annealing simulations

This paper presents a methodology based on geostatistical theory for quantifying the risks associated with heavy-metal contamination in the harbor area of Santana, Amapá State, Northern Brazil. In this area there were activities related to the commercialization of manganese ore from Serra do Navio. Manganese and arsenic concentrations at unsampled sites were estimated by postprocessing results from stochastic annealing simulations; the simulations were used to test different criteria for optimization, including average, median, and quantiles. For classifying areas as contaminated or uncontaminated, estimated quantiles based on functions of asymmetric loss showed better results than did estimates based on symmetric loss, such as the average or the median. The use of specific loss functions in the decision-making process can reduce the costs of remediation and health maintenance. The highest global health costs were observed for manganese.     

Spatial modelling of commercial spaces in medium-sized cities

The pattern of commercial spaces in a city has never been the consequence of chance. Retailers have always searched for the ‘best location’, but the notion of what exactly constitutes the ‘best location’ has changed over the decades. It is no longer a question of being close-to-market. It depends on an amount of social, economic and even morphological aspects of urban life, not to mention intrinsic aspects of the retail sector itself, namely new types of stores, products and purchase and payment options. Consequently, the methods retailers have employed to determine ‘best location’ have also evolved, and today increasingly complex mathematical and geospatial models are in use. It should then be safe to assume that commercial geography has changed and therefore, commercial hierarchies need to be re-invented, or at least challenged. A current trend in the literature is revealing more than ever the influence of commerce in the spatial and morphological re-configuration of cities. Thus, the understanding of modern retail patterns may be a key issue in interpreting and regulating the processes of urban, social and economic development. Using as test-beds four Portuguese medium-sized cities, commercial and morphological data was collected, analysed and compared, applying spatial analysis techniques. Similar patterns were found between the four cities, which led to the proposal of two geospatial commercial distribution models, one for the city-centre and one for the suburbia. These models shed a new light on the structure of Portuguese medium-size cities, and may well be valid in other medium and small towns across Europe.     

Reconstruction of food conditions for Northeast Atlantic bivalve species based on Dynamic Energy Budgets

Required assimilated energy to support observed growth was reconstructed for four common bivalve species (Mya arenaria, Cerastoderma edule, Mytilus edulis and Macoma balthica) from various Northeast Atlantic coastal areas, along the species distributional range. The approach applied was based on the Dynamic Energy Budget (DEB) theory whereby observed growth patterns in the field, in combination with prevailing temperatures, were used to reconstruct the average food intake experienced in the field scaled to the maximum possible. For all species, results suggest food limitation over the range of locations. In general, reconstructed food intake indicated better conditions for C. edule compared to the other species, while M. edulis presented the lowest food conditions in all the areas. Despite the indications for a latitudinal trend in primary production, no clear pattern or relationship between reconstructed food conditions and latitude was observed suggesting that any trend may be overruled by local conditions.     

Hydrograph separation using tracers and digital filters to quantify runoff components in a semi‐arid mesoscale catchment

Chemical hydrograph separation using electrical conductivity and digital filters is applied to quantify runoff components in the 1,640 km² semi‐arid Kaap River catchment and its subcatchments in South Africa. A rich data set of weekly to monthly water quality data ranging from 1978 to 2012 (450 to 940 samples per site) was analysed at 4 sampling locations in the catchment. The data were routinely collected by South Africa's national Department of Water and Sanitation, using standard sampling procedures. Chemical hydrograph separation using electrical conductivity (EC) as a tracer was used as reference and a recursive digital filter was then calibrated for the catchment. Results of the two‐component hydrograph separation indicate the dominance of baseflow in the low flow regime, with a contribution of about 90% of total flow; however, during the wet season, baseflow accounts for 50% of total flow. The digital filter parameters were very sensitive and required calibration, using chemical hydrograph separation as a reference. Calibrated baseflow estimates ranged from 40% of total flow at the catchment outlet to 70% in the tributaries. The study demonstrates that routinely monitored water quality data, especially EC, can be used as a meaningful tracer, which could also aid in the calibration of a digital filter method and reduce uncertainty of estimated flow components. This information enhances our understanding of how baseflow is generated and contributed to streamflow throughout the year, which can aid in quantification of environmental flows, as well as to better parameterize hydrological models used for water resources planning and management. Baseflow estimates can also be useful for groundwater and water quality management.