Regional characteristics and the decision to innovate in a developing country: A multilevel analysis of Ecuadorian firms

This is the first study that uses multilevel modelling to analyse regional influence on the decision to invest in innovation activities of firms in a single developing country, Ecuador. Our results indicate that the decision to invest in R&D and in other innovation activities are conditioned by the region in which the firm is located. Regional loan volume, orientation towards knowledge exploitation and intra-regional-sectorial R&D spillovers are positively associated with both types of innovation activities, while regional levels of co-operation and inter-regional R&D spillovers are only positively associated with the probability of investing in other innovation activities.     

Zebrafish larvae as a model for the evaluation of inorganic arsenic and tributyltin bioconcentration

The European REACH legislation establishes the need to study the toxicity, persistence and bioaccumulation of those chemicals with an exceeding production of 100 tons and/or chemicals considered PBTs substances (Persistence, Bioaccumulation and Toxicity). Currently, the OECD technical guideline 305 is the most used protocol to determine bioconcentration factors of contaminants in aquatic environments. However, this procedure implies high cost and amount of adult fishes. Zebrafish (Danio Rerio) has been selected since this animal model has several advantageous features over other vertebrates, mainly fast embryonic development and easy growth. The analytical methodology here developed has been applied to calculate the bioconcentration factors (BCFs) of two contaminants: inorganic arsenic and tributyltin (measured as arsenic and tin). The method is based on the use of an ultrasonic probe assisted extraction for accelerating the sample treatment followed by detection using graphite furnace atomic absorption spectrometry with Zeeman correction (ZGFAAS). Results obtained for the BCFs values are in good agreement with previously reported data on freshwater aquatic organisms. In the case of arsenic, after exposing larvae to concentrations of 5 and 50 μg L⁻¹, very low BCFs were observed (between 2.2 and 9.5); while for tributyltin, the BCFs observed were within the range 840-1280 after exposure to concentrations of 0.2 and 2.0 μg L⁻¹, respectively. This study shows the use of zebrafish larvae together with the proposed analytical approach as a promising alternative to the OECD 305 test to evaluate the BCFs of classical and emergent contaminants.     

The effect of sampling design on extensive bryomonitoring surveys of air pollution

In this study, we investigated if the different sampling designs normally used in extensive bryomonitoring surveys of air pollution allow compliance with the objectives proposed in the 'Heavy Metals in European Moss' project. For this, we have used data on concentrations of As, Cu, Se and Zn from five moss sampling surveys carried out in Galicia (NW Spain), using three types of sampling design: regular grid, sampling sites inside squares and the strategy recommended in the guidelines for European surveys. To study the effect of the interaction between the sampling design and the spatial pattern of the presence of contaminants, we have used a simulated and a real pattern onto which we superimposed the three sampling designs considered. We found that only random sampling and grid sampling allow compliance with the proposed objectives, and we discuss the advantages of the latter over the former. The data corresponding to studies using different sampling designs are not comparable, and in future large-scale surveys, the same design must be used if the results are to be compared and if valid conclusions are to be reached. The scale of the grid determines the scale to which the objectives are complied with, so that for correct standardization of the technique, and taking into account the most commonly used grid sizes, we recommend a grid size of 30 x 30 or 32 x 32 km. When additional samplings are required, the size of the grid size should be 30/2(n) or 32/2(n) km.     

Distribution and mobility of mercury in soils from an old mining area in Mieres, Asturias (Spain)

Mercury content in soils near abandoned mine wastes in the mercury mining area of Mieres (Asturias, Spain) is highly elevated as a result of the long period of mining and abundant Hg production. In this work, an evaluation of Hg concentration, distribution, and mobility in three soil samples from the immediate vicinity of a chimney used for vapour evacuation during pyrometallurgical treatment of the ore was carried out. For that purpose, total Hg contents were determined for the original samples and their grain-size subsamples. The study of mercury mobility in the original samples and in the different particle-size subsamples was made by the application of a sequential extraction method. Results showed that Hg concentration in soils decreases directly with the distance from the chimney and the dispersion of Hg is not influenced by the topographic height of the site tested. The sample collected in the base of the chimney exhibited appreciable amounts of mobile Hg. In general, a higher Hg concentration was found for the finest particle-size subsamples. Hg mobility was found to be higher for quite developed soils. The sample collected downstream from the chimney showed a significant Hg mobile content as a result of a more intensive weathering. An increase of Hg mobility at decreasing particle size was found in all three analysed samples.     

Assessment of heavy metal levels in Almendares River sediments--Havana City, Cuba

The Almendares River watershed covers a large portion of Havana, Cuba and is centrally important to both recreational and other activities in the region. In order to assess current water quality conditions prior to planned remediation efforts, the spatial distribution of six heavy metals and other compounds were determined in river sediments at fifteen sampling stations in the watershed. Metal concentrations in sediments ranged from 86.1 to 708.8 for Zn, 39.3 to 189.0 for Pb, 71.6 to 420.8 for Cu, 84.4 to 209.7 Cr, 1.5 to 23.4 for Co, and 1.0 to 4.3 for Cd microg/g dry weight sediment. Calculated enrichment factors (EF; measured metal versus background mineral conditions) were almost always greater than 1.0, suggesting significant anthropogenic impact on metal levels in the river. The highest EF values were seen immediately below Cotorro (EF>10 for Pb, Cu, and Cd), a suburban town that has an active secondary smelter, and below the largest municipal landfill in Havana (EF>10 for Pb, Cu, Cd, and Zn). Further, three sampling stations had multiple metals at concentrations higher than probable effects concentrations (PEC), implying possible local ecotoxicological impacts. Finally, sequential extractions of the sediments indicated that heavy metals were largely associated with the organic fraction, and it was estimated that up to 62% of metals in the sediments would be susceptible to release back into the water column if hydraulic or other changes occurred in the river. These data are being used to prioritize decisions related to the remediation of the river system.     

Removal and recovery of Cr(VI) from polluted ground waters: a comparative study of ion-exchange technologies

The focus of this work has been the study of Cr(VI) removal from ground waters and the simultaneous concentration for its reuse using three different technological alternatives: anion-exchange resins, liquid-liquid extraction assisted by hollow fibre membranes and emulsion pertraction. The viability of the considered objectives, i.e., Cr(VI) separation (<0.5 g/m3) and concentration for reuse (>20,000 g/m3) has been checked and a comparative analysis of the three technologies has been performed. Although the flexibility and ease of operation of non-dispersive solvent extraction, anion-exchange resins and emulsion pertraction lead to higher velocities of chromium removal, yet still maintaining similar concentration efficiencies.     

Environmental assessment of an uncontrolled sanitary landfill,Pocos de Caldas,Brazil

There are more than 20,000 uncontrolled sanitary landfill areas in Brazil. The paper reports an integrated study undertaken to develop an environmental assessment of the uncontrolled sanitary landfill area of the city of Po?os de Caldas, State of Minas Gerais, Brazil. A number of remedial alternatives were evaluated. The USGS modular 3D finite difference groundwater flow model (Modflow) and Modular 3D Finite Difference Mass Transport Model (MT3D) software were used to simulate groundwater flow and contaminant transport modelling, as well as to predict changes due to the proposed remediation measures. The remedial alternatives considered for normal conditions from 20 to 40 year periods were waste removal, vertical cut-off barriers, extraction wells and top capping. The results indicated that extraction wells and waste removal are the best alternatives because they significantly reduce both the extension and levels of the contamination plume even after 5 years. The extraction well proved a less expensive remedial alternative than waste removal.      

Self-cleaning in an estuarine area formerly affected by 226Ra anthropogenic enhancements: numerical simulations

A numerical model of the Odiel-Tinto estuary (Spain) has been developed to study the self-cleaning process that was evidenced from 226Ra measurements in water and sediments collected in the period 1999-2002, after direct releases from a fertilizer complex ceased (in 1998). The hydrodynamic model is first calibrated, and standard tidal analysis is carried out to calculate tidal constants required by the dispersion code to determine instantaneous water currents and elevations over the estuary. In this way, long-term simulations may be carried out. The dispersion code includes advective/diffusive transport of radionuclides plus exchanges with bottom sediments described through a kinetic approach. The dispersion model is first tested by comparing computed and measured 226Ra concentrations over the estuary resulting after releases in the Odiel and Tinto rivers. Next, it is applied to simulate the self-cleaning process of the estuary. The time evolution of radium concentrations in bed sediments is in generally good agreement with observations. The computed sediment halving time of the estuary is 510 days, which also is in good agreement with that estimated from measurements.     

Estimation of stresses in atmospheric ice during aeolian vibration of power transmission lines

Aeolian vibration in bare and iced cable was simulated using the theory of cable vibration. High frequency vibration creates stresses in the cable and consequently in the ice covering that cable, which may result in ice failure and eventually ice shedding. These stresses were estimated in this study. Displacement of the cable during vibration was determined; furthermore, instantaneous wind loads in vertical and transverse directions, additional stresses induced by the motion in the cable and in the atmospheric ice, as well as torque due to cable springback were calculated. In order to simulate the loading conditions of a chunk of atmospheric ice in the middle of a span, a new model was developed using ABAQUS. Results from this model show in spite of high frequency vibration, the resulting level of stress in atmospheric ice is far less than its failure limit. In other words, the atmospheric ice under the condition assumed in this investigation does not shed due to aeolian vibration.