Understanding slums: analysis of the metabolic pattern of the Vidigal favela in Rio de Janeiro,Brazil

This paper illustrates an innovative approach to characterize the metabolic pattern of informal urban settlements or slums with the aim to better understand the factors that affect the material standard of living of slum residents, the dynamics of slum development and the interaction of the slum with its wider socioeconomic context. The proposed system of accounting, multi-scale integrated analysis of societal and ecosystem metabolism (MuSIASEM), integrates socioeconomic and spatial data and studies energy and monetary flows in relation to the pattern of human activities and land uses. The theoretical basis of the approach is illustrated with data from Vidigal favela in Rio de Janeiro, Brazil. In particular, we show how to construct taxonomies of accounting categories to characterize: (1) the set of activities carried out by the slum dwellers, to which to link assessments of flow rates per hour; (2) the set of land uses or spatial elements making up the slum, to which to link assessments of flow densities per hectare. The analysis of the interaction of Vidigal with its wider socioeconomic context focuses on monetary flows and transport (job commuting).     

Regional integration and local change: road paving, community connectivity, and social–ecological resilience in a tri-national frontier, southwestern Amazonia

Initiatives for global economic integration increasingly prioritize new infrastructure in relatively remote regions. Such regions have relatively intact ecosystems and provide valuable ecosystem services, which has stimulated debates over the wisdom of new infrastructure. Most prior research on infrastructure impacts highlights economic benefits, ecological damage, or social conflicts. We suggest a more integrative approach to regional integration by appropriating the concepts of connectivity from transport geography and social?Cecological resilience from systems ecology. Connectivity offers a means of observing the degree of integration between locations, and social?Cecological resilience provides a framework to simultaneously consider multiple consequences of regional integration. Together, they offer a spatial analysis of resilience that considers multiple dimensions of infrastructure impacts. Our study case is the southwestern Amazon, a highly biodiverse region which is experiencing integration via paving of the Inter-Oceanic Highway. Specifically, we focus on the ??MAP?? region, a tri-national frontier where Bolivia, Brazil, and Peru meet and which differs in the extent of highway paving. We draw on a tri-national survey of more than 100 resource-dependent rural communities across the MAP frontier and employ indicators for multiple dimensions of connectivity and social?Cecological resilience. We pursue a comparative analysis among regions and subregions with differing degrees of community connectivity to markets in order to evaluate their social?Cecological resilience. The findings indicate that connectivity and resilience have a multifaceted relationship, such that greater community connectivity corresponds to greater resilience in some respects but not others. We conclude by noting how our findings integrate those from heretofore largely disparate literatures on infrastructure. The integration of transport geography with resilience thought thus stands to advance the study of infrastructure impacts.     

Soil-plant-animal transfer models to improve soil protection guidelines: a case study from Portugal

Food chain models are essential tools to assess risks of soil contamination in view of product quality including fodder crops and animal products. Here we link soil to plant transfer (SPT) models for potentially toxic elements (PTEs) including As, Ba, Cd, Co, Cu, Hg, Ni, Pb, Sb, U and Zn with models describing accumulation in animal organs. Current EU standards for food products and acceptable daily intake levels (ADI) for humans were used as critical limits. The combined model is used to assess the impact of soil contamination on animal health, product quality and human health using data from 100 arable fields. Results indicate that 42 existing arable fields near industrial and mining sites are unsuitable for animal grazing in view of food safety due to elevated intake of Cd, Cu, Hg and Pb by cows and sheep. At 10 sites daily intake levels of As by cows exceeded threshold concentrations regarding the quality of animal products.The food chain model also was used inversely to derive soil threshold concentrations in view of EU fodder standards. Calculated threshold levels in soil for As, Cd, Cu, Pb, Hg and Zn appear to be in line with those proposed or used in other EU countries. As such the approach applied here can form a conceptual basis for a more harmonized risk assessment strategy regarding the protection of animal and human health.     

Nutrients and nonessential elements in soil after 11 years of wastewater irrigation

Irrigation of citrus (Citrus aurantium L. × Citrus paradise Macf.) with urban reclaimed wastewater (RWW) can be economical and conserve fresh water. However, concerns remain regarding its deleterious effects on soil quality. We investigated the ionic speciation (ISP) of RWW and potential impacts of 11 yr of irrigation with RWW on soil quality, compared with well-water (WW) irrigation. Most of nutrients (～53-99%) in RWW are free ionic species and readily available for plant uptake, such as: NH(4+), NO(3-), K(+), Ca(2+), Mg(2+), SO(4)(2-), H(3)BO(3), Cl(-), Fe(2+), Mn(2+), Zn(2+), Co(2+), and Ni(2+), whereas more than about 80% of Cu, Cr, Pb, and Al are complexed with CO(3-), OH(-), and/or organic matter. The RWW irrigation increased the availability and total concentrations of nutrients and nonessential elements, and soil salinity and sodicity by two to three times compared with WW-irrigated soils. Although RWW irrigation changed many soil parameters, no difference in citrus yield was observed. The risk of negative impacts from RWW irrigation on soil quality appears to be minimal because of: (i) adequate quality of RWW, according to USEPA limits; (ii) low concentrations of metals in soil after 11 yr of irrigation with RWW; and (iii) rapid leaching of salts in RWW-irrigated soil during the rainy season.     

Laboratory study on leachability of five herbicides in South Australian soils

Abstract

Norflurazon, oxadiazon, oxyfluorfen, trifluralin and simazine are herbicides widely used in the vineyards of the Barossa Valley, South Australia. The leaching behaviour of norflurazon, oxadiazon, oxyfluorfen and trifluralin was investigated on four key soils in the Barossa Valley. Leaching potential on packed soil columns and actual mobility using intact soil columns were investigated. On the packed soil columns, norflurazon was the most leachable herbicide. More of the herbicides were detected in the leachates from the sandy soils (Mountadam and Nuriootpa) than from the clayey soils (Lyndoch and Tanunda). Organic matter is generally low in soils in the Barossa region. Porosity and saturated conductivity significantly affect herbicide movement and in the sandy Mountadam and Nuriootpa soils, the water flux is greater than for the higher clay content Lyndoch and Tanunda soils. Increasing the time interval between herbicide application and the incidence of “rainfall”; reduced the amounts of herbicides found in the leachates. The use of intact soil columns and including simazine for comparison showed that both norflurazon and simazine were present in the leachates. Simazine was the first herbicide to appear in leachates. Sectioning of the intact soil columns after leaching clearly demonstrated that norflurazon and simazine reached the bottom of the soil columns for all soils studied. Greater amounts of norflurazon were retained in the soil columns compared with simazine. The other herbicides were mostly retained in the initial sections of the soil columns.     

Efficiency of a cleanup technology to remove mercury from natural waters by means of rice husk biowaste: ecotoxicological and chemical approach

In the present work, the efficiency of rice husk to remove Hg(II) from river waters spiked with realistic environmental concentrations of this metal (μg L^?1 range) was evaluated. The residual levels of Hg(II) obtained after the remediation process were compared with the guideline values for effluents discharges and water for human consumption, and the ecotoxicological effects using organisms of different trophic levels were assessed. The rice husk sorbent proved to be useful in decreasing Hg(II) contamination in river waters, by reducing the levels of Hg(II) to values of ca. 8.0 and 34 μg L^?1, for an Hg(II) initial concentration of 50 and 500 μg L^?1, respectively. The remediation process with rice husk biowaste was extremely efficient in river waters spiked with lower levels of Hg(II), being able to eliminate the toxicity to the exposed organisms algae Pseudokirchneriella subcapitata and rotifer Brachionus calyciflorus and ensure the total survival of Daphnia magna species. For concentrations of Hg(II) tenfold higher (500 μg L^?1), the remediation process was not adequate in the detoxification process, still, the rice husk material was able to reduce considerably the toxicity to the bacteria Vibrio fischeri, algae P. subcapitata and rotifer B. calyciflorus, whose responses where fully inhibited during its exposure to the non-remediated river water. The use of a battery of bioassays with organisms from different trophic levels and whose sensitivity revealed to be different and dependent on the levels of Hg(II) contamination proved to be much more accurate in predicting the ecotoxicological hazard assessment of the detoxification process by means of rice husk biowaste.     

Influence of Some Chelators on the Phytoextraction Ability of Sunflower (Helianthus annuus) for Nickel‐Contaminated Soil

Chelation and complexation of nickel were evaluated as practical ways to solubilize, detoxify, and enhance nickel accumulation by plants. Sunflower (Helianthus annuus) was selected as a potential nickel accumulator in two selected soils with different textures and nickel‐contamination levels. To enhance metal phytoextraction, ammonium nitrate and organic chelators (EDTA and citric acid) were added to soils in pots at rates of 0, 5, 10, and 20 mmol/kg. The pot experiments were run for eight weeks. The highest nickel uptake was obtained in plants grown on clayey soil, and the lowest uptake was observed in sandy soil. Citric acid was the most effective chelator of nickel metals that could enhance nickel accumulation in the sunflower shoots. The ammonium nitrate application showed a low effect on metal translocation into the sunflower shoots. © 2014 Wiley Periodicals, Inc.