Laboratory study on the leaching potential of spent alkaline batteries

Four different leaching tests were carried out with spent alkaline batteries as an attempt to quantify the environmental potential burdens associated with landfilling. The tests were performed in columns filled up with batteries either entire or cross-cut, using either deionized water or nitric acid solution as leachant. In a first set of tests, the NEN 7343 standard procedure was followed, with leachant circulating in open circuit from bottom to top through columns. These tests were extended to another leaching step where leachant percolated the columns in a closed loop process.Leachate solutions were periodically sampled and pH, conductivity, density, redox potential, sulphates, chlorides and heavy metals (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Tl and Zn) were determined in the samples.The results showed that the total amount of substances leached in tests with cross-cut batteries was higher than with entire ones; zinc and sulphates were the substances found the most in the leachate solutions. In general, the amount of substances dissolved in open circuit is higher than in closed loop due to the effect of solution saturation and the absence of fresh solution addition.Results were compared with metal contents in the batteries and with legal limits for acceptance in landfill (Decision 2003/33/CE and Decree-Law 152/2002). None of the metals were meaningfully dissolved comparatively to its content in the batteries, except Hg. Despite the differences in the experiment procedure used and the one stated in the legislation (mixing, contact time and granulometry), the comparison of results obtained with cross-cut batteries using deionized water with legal limits showed that batteries studied could be considered hazardous waste.     

Continuous-feeding vermicomposting as a recycling management method to revalue tomato-fruit wastes from greenhouse crops

Huge quantities of discarded fruits generated from greenhouse crops represent a worldwide environmental problem. The aim of this work was to assess the efficiency of vermicomposting as a recycling management option for biotransforming tomato-fruit wastes from greenhouses into an organic nutrient-rich product available for agricultural purposes. A pilot vermireactor was constructed. It was provided with a manure layer, where an initial population of Eisenia fetida was introduced and fed continuously at a high organic loading rate (13.6 kg TOC m^?3 wk^?1) for 150 days. Vermicompost chemical and enzymatic parameters as well as the bacterial and fungal community structure were determined for 210 days (vermicomposting plus a maturation period). Earthworm biomass increased after 90 days, and then declined due to increasing pH, electrical conductivity and ammonium concentration. The temporal patterns of dehydrogenase, β-glucosidase, protease and urease were related to earthworm growth and the stabilization of organic matter. Bacterial DGGE profiles differed between the period of degradation of labile substrates and the maturation step. Fungal communities at the stage of maximum earthworm biomass differed most, suggesting a gut passage effect. The end product was chemically stable and enriched in nutrients, demonstrating that tomato-fruit wastes can be successfully vermicomposted into a valuable soil amendment. We suggest continuous-feeding vermicomposting as an environmentally sound management option for greenhouse wastes.     

Determination of organic compounds in landfill leachates treated by Fenton–Adsorption

The objective of this study was to identify the organic compounds removed from the leachate when treated with Fenton–Adsorption by gas chromatography coupled to mass spectrometry (GC–MS) in order to identify toxic compounds that could be harmful for the environment or human health.The physicochemical characterization of the raw leachate was carried out before and after the Fenton–Adsorption process. The effluent from each stage of this process was characterized: pH, Biological Oxygen Demand (BOD₅), Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), Total Carbon (TC), Inorganic Carbon (IC), Total Solids (TS), Total Suspended Solids (TSS) and Color. The organic compounds were determined by GC–MS.The removal of COD and color reached over 99% in compliance with the Mexican Standard NOM-001-SEMARNAT-1996, which establishes the maximum permissible limits for contaminants present in wastewater discharges to water and national goods. The chromatographic analysis from the Fenton–Adsorption effluent proved that this treatment removed more than 98% of the organic compounds present in the initial sample. The mono (2-ethylhexyl) ester 1,2-benzenedicarboxylic acid persisted, although it is not considered as toxic compound by the NOM-052-SEMARNAT-2005. Therefore, the treated effluent can be safely disposed of into the environment.     

Composting kinetics in full-scale mechanical–biological treatment plants

This study focuses on the investigation of the kinetics of municipal solid waste composting in three full-scale mechanical–biological treatment (MBT) plants. The aims were to test a kinetic model based on volatile solids (VS) content change for describing the composting process in MBT plants, and to identify the model parameters that affected the estimation of the reaction rate constant most. To achieve this, VS content and several environmental conditions, namely temperature, moisture content, oxygen concentration and total bulk density were monitored throughout the composting process. Experimental data was fitted with a first-order kinetic model, and a rate constant (k) characteristic of composting under optimum environmental conditions was obtained. The kinetic model satisfactorily described the experimental data for the three MBT plants. k values ranged from 0.043 ± 0.002 d^?1 to 0.082 ± 0.011 d^?1. Sensitivity analysis showed that the model parameters that most affected the estimation of k were the initial biodegradable volatile solids content, the maximum temperature for biodegradation and the optimum moisture content. In conclusion, we show for the first time that full-scale MBT plants can be successfully modelled with a composting kinetic model.     

Inferring pollution records in sediment cores from transitional environments of Marquelia coast,Guerrero, Mexico

Environmental Science and Pollution Research - The vertical distribution pattern and concentrations of elements (Fe, Al, Ca, Mg, Mn, Cr, Cu, Ni, Co, Pb, Zn, and As) in the estuarine and lagoon...     

The effects of plant distribution and frugivore density on the scale and shape of dispersal kernels

For many plant species, seed dispersal is one of the most important spatial demographic processes. We used a diffusion approximation and a spatially explicit simulation model to explore the mechanisms generating seed dispersal kernels for plants dispersed by frugivores. The simulation model combined simple movement and foraging rules with seed gut passage time, plant distribution, and fruit production. A simulation experiment using plant spatial aggregation and frugivore density as factors showed that seed dispersal scale was largely determined by the degree of plant aggregation, whereas kernel shape was mostly dominated by frugivore density. Kernel shapes ranged from fat tailed to thin tailed, but most shapes were between an exponential and that of the solution of a diffusion equation. The proportion of dispersal kernels with fat tails was highest for landscapes with clumped plant distributions and increased with increasing number of dispersers. The diffusion model provides a basis for models including more behavioral details but can also be used to approximate dispersal kernels once a diffusion rate is estimated from animal movement data. Our results suggest that important characteristics of dispersal kernels will depend on the spatial pattern of plant distribution and on disperser density when frugivores mediate seed dispersal.     

Heavy metals contents in agricultural topsoils in the Ebro basin (Spain). Application of the multivariate geoestatistical methods to study spatial variations

In this work the content of seven heavy metals (Cd, Cr, Cu, Hg, Ni, Pb and Zn) and other parameters (the pH, organic matter, carbonates and granulometric fraction) in agricultural topsoil in the Ebro basin are quantified, based on 624 samples collected according to an 8 by 8 km square mesh. The average concentrations (mg/kg) obtained were: Cd 0.415+/-0.163, Cr 20.27+/-13.21, Cu 17.33+/-14.97, Ni 20.50+/-22.71, Pb 17.54+/-10.41, Zn 17.53+/-24.19 and Hg 35.6+/-42.05 microg/kg. The concentration levels are relatively low in areas of high pH and low organic matter content concentration. The results of factor analysis group Cd, Cu, Hg, Pb and Zn in F1 and Cr y Ni in F2. The spatial heavy metals component maps based on geostatistical analysis, show definite association of these factors with the soil parent material. The local anomalies (found in Cu, Zn and Pb) are attributed to anthropogenic influence.     

First fossil evidence of an “interglacial refugium” in the Pyrenean region

A refugium is generally understood as an area where temperate species survive cold periods, such as the Iberian, Italian, or Balkan Peninsulas in Europe. Strictly speaking, this definition refers to what is known as a glacial refugium. However, there are various types of lesser-known refugia such as the interglacial refugium, which denotes a mountainous region at low latitudes, such as the Pyrenees, where species adapted to the cold survive during interstadial periods. The small-vertebrate association from the sequence of Cova Colomera, which is located on the southern face of the Pyrenees and contains the final cold spell of the Late Pleistocene and the beginnings of the temperate period in which we currently find ourselves (the Holocene), could constitute the first fossil evidence of such an interglacial refugium, thus providing new paleoecological data on the phenomenon.     

Evaluation of soil erosion risk using Analytic Network Process and GIS: A case study from Spanish mountain olive plantations

The study presents an approach that combined objective information such as sampling or experimental data with subjective information such as expert opinions. This combined approach was based on the Analytic Network Process method. It was applied to evaluate soil erosion risk and overcomes one of the drawbacks of USLE/RUSLE soil erosion models, namely that they do not consider interactions among soil erosion factors. Another advantage of this method is that it can be used if there are insufficient experimental data. The lack of experimental data can be compensated for through the use of expert evaluations. As an example of the proposed approach, the risk of soil erosion was evaluated in olive groves in Southern Spain, showing the potential of the ANP method for modelling a complex physical process like soil erosion.