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Madrid, Spain

This study was designed to determine the state of polluted soils in the main landfills of the Community of Madrid (central Spain), as part of a continuous assessment of the impacts of urban solid waste (USW) landfills that were capped with a layer of soil 20 years ago. Our analysis of this problem has been highly conditioned by the constant re-use of many of the USW landfills, since they have never been the target of any specific restoration plan. Our periodical analysis of cover soils and soils from discharge areas of the landfills indicates soil pollution has worsened over the years. Here, we examined heavy metal, salts, and organic compounds in soil and surface water samples taken from 15 landfills in the Madrid region. Impacts of the landfill soil covers on nematode and plant diversity were also evaluated. These analyses continue to reveal the presence of heavy metals (Zn, Cu, Cr, Ni, Pb, Cd) in soils, and salts (sulphates, chlorides and nitrates) in soils and surface waters. In addition, non-agricultural organic compounds, mainly aromatic and aliphatic hydrocarbons, often appeared in very high concentrations, and high levels of insecticides such as gamma-HCH (lindane) were also detected in soils. Around 50% of the water samples collected showed chemical demand of oxygen (CDO) values in excess of 150mg/l. Traces of phenolic compounds were detected in some landfills, some of which exhibited high levels of 2-chlorophenol and pentachlorophenol. All these factors are conditioning both the revegetation of the landfill systems and the remediation of their slopes and terrestrial ecosystems arising in their discharge areas.This work updates the current situation and discusses risks for the health of the ecosystems, humans, domestic animals and wildlife living close to these landfills. © 2011 Elsevier Ltd. Source

Dorado J.,CSIC - Institute of Agricultural Sciences | Almendros G.,MNCN | Gonzalez-Vila F.J.,Institute Recursos Naturales y Agrobiologia IRNAS
Journal of Analytical and Applied Pyrolysis

The effects on the structural features of humic acids (HA) from dryland farming soils under long term management practices have been approached by analytical pyrolysis (Curie-point pyrolysis-gas chromatography/mass spectrometry, Py-GC/MS). The field experiments (started in 1987) include conventional, minimum and no-tillage plots, as well as non cultivated plots. The HAs isolated from the various plots showed significant differences in their pyrolytic behavior, in particular regarding the total abundances of alkyl pyrolysis compounds (fatty acids, alkenes and alkanes). The occurrence of very short-chain fatty acids (C5-C11) in uncultivated plots could be indicative of constitutional alkyl structures in the relictual HA from undisturbed soil. The effect of soil tillage managements substantially increased total abundances of fatty acids in plots under conservation practices (mainly no-tillage). The HAs from uncultivated soils showed the greatest percentages of alkanes and alkenes. This was associated to the increased proportions of even C-numbered alkene homologues from C12 to C18, possibly related to the incorporation of microbial compounds during the humification process. High percentage of alkylbenzenes and catechols were also characteristic of the uncultivated plots. The increased proportions of methoxyphenols, in special of the syringyl (dimethoxyphenyl) type, in HAs from plots subjected to conventional tillage pointed out to humification processes based on progressive alteration of plant lignins. From the viewpoint of soil quality, the results suggest comparatively advanced transformation stages of the HA from uncultivated plots, which means that conservation tillage practices seems to lead to increasing soil C levels, at expenses of the accumulation of comparatively recent organic matter derived either from altered lignins and/or microbial biomass. © 2015 Elsevier B.V. All rights reserved. Source

Gutierrez-Gines M.J.,Science Building | Pastor J.,MNCN | Hernandez A.J.,Science Building
Environmental Sciences: Processes and Impacts

In soil pollution studies, large numbers of soil samples collected at random need to be processed and analyzed to determine their heavy metal contents. This study was designed to assess the use of a field portable X-ray fluorescence (FPXRF) spectrometry system for the in situ determination of heavy metal levels in both soil and plant samples. First, we optimised the method using 84 reference soil standards and soil samples from known polluted sites. The optimised method was then used to determine heavy metals at three abandoned mine sites and two sealed landfills in central Spain. Given that knowledge of heavy metal levels in plants is important for the ecotoxicological study of these sites, the FPXRF device was also used to determine heavy metals in plants. Our results indicate the acceptable to high quality of the data provided by the system especially for soil samples. The cost-benefits and sustainability of this instrument in relation to other techniques were also examined. The use of the FPXRF system for the study of potentially polluted sites was found to save on costs, time and materials. Results indicate its suitable use for the preliminary screening of heavy-metal polluted sites. © 2013 The Royal Society of Chemistry. Source

de Blas E.,University of Vigo | Almendros G.,MNCN | Sanz J.,Institute Quimica Organica General

There is little information available about the molecular composition of organic fractions with a possible bearing in soil water repellency. Extremely water-repellent forest soils developed on granites or schists, under vegetation of pine or eucalyptus, were used for sequential isolation of two lipid fractions: free lipid extracted with petroleum ether and 'bound' lipid obtained with the same solvent after 2M H3PO4 pre-treatment. Soil water repellency tests were carried out, and lipids were analyzed by gas chromatography/mass spectrometry (GC-MS). Free lipids in soils under eucalyptus consisted mainly of sesquiterpenes (globulol, aromadendrene, eudesmol and ledene) whereas soils under pine included diterpene resin acids (mainly dehydroabietic, pimaric and seco-dehydroabietic) and phenol. Free alkanes (C15 to C37) displayed homologous series typical in epicuticular waxes, whereas free fatty acids series showed bimodal distribution.'Bound' lipids consisted almost exclusively of fatty acids (mainly C16 and C18 acids), and alkanes (maximum at C27 or C28 and no even-to-odd C-number preference). Major compounds related to soil water repellency are typically found in higher plants and are not synthesized by microorganisms. After removing free lipids, soil water repellency decreased slightly but remained extreme. After extraction of bound lipids, the repellency considerably decreased, but did not disappear completely. As regards the effect of the lipid fractions in soil water repellency, it was clear the dominant role of the vegetation type in the case of free lipid, whereas for bound lipid, repellency mainly represents an emergent property arising from strong interaction between organic matter and the geological material. The results suggest that soil lipids only explain a part of the soil water repellency, which also depends on surface properties of the soil matrix, i.e., not only depends on hydrophobic coatings but probably of diffusion of hydrophobic cements into micellar associations self-organized into zonal structures in humus-clay matrix. © 2013 Elsevier B.V. Source

Gutierrez-Gines M.J.,University of Alcala | Pastor J.,MNCN | Hernandez A.J.,University of Alcala

This study addresses the effects of soil polluted with more than one heavy metal in a grass species. A 16-week bioassay with Avena sativa L. was conducted in microcosms using soils from two abandoned mines in central Spain that contained levels above World Health Organization (WHO) reference limits for soils of more than three heavy metals. Pollution effects were examined at cell, tissue, organ, plant and population levels. For this purpose, dry weight, maximum height and number of leaves were determined; leaf tissues were observed by low temperature scanning electron microscopy; the metal contents of roots and shoots were determined by plasma emission spectroscopy and their distribution in different tissues was analyzed by X-ray microanalysis using an environmental scanning electron microscope. The results explain the accumulation and translocation of soil metals by this plant species; their effects in cells, tissues and growth of plants; and allow inference on population effects. The discussion of the methodological approach leads us to propose a valid protocol to assess the effects of a set of heavy metals present in the topsoil of polluted sites on a plant population. We recommend its use for an ecotoxicological diagnosis and risk analysis of similarly polluted sites. © Springer Science+Business Media, LLC 2012. Source

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