Chemical speciation and mobilization of copper and zinc in naturally contaminated mine soils with citric and tartaric acids

A one-step extraction procedure and a leaching column experiment were performed to assess the effects of citric and tartaric acids on Cu and Zn mobilization in naturally contaminated mine soils to facilitate assisted phytoextraction. A speciation modeling of the soil solution and the metal fractionation of soils were performed to elucidate the chemical processes that affected metal desorption by organic acids. Different extracting solutions were prepared, all of which contained 0.01 M KNO3 and different concentrations of organic acids: control without organic acids, 0.5 mM citric, 0.5 mM tartaric, 10 mM citric, 10 mM tartaric, and 5 mM citric +5 mM tartaric. The results of the extraction procedure showed that higher concentrations of organic acids increased metal desorption, and citric acid was more effective at facilitating metal desorption than tartaric acid. Metal desorption was mainly influenced by the decreasing pH and the dissolution of Fe and Mn oxides, not by the formation of soluble metal–organic complexes as was predicted by the speciation modeling. The results of the column study reported that low concentrations of organic acids did not significantly increase metal mobilization and that higher doses were also not able to mobilize Zn. However, 5–10 mM citric acid significantly promoted Cu mobilization (from 1 mg kg−1 in the control to 42 mg kg−1 with 10 mM citric acid) and reduced the exchangeable (from 21 to 3 mg kg−1) and the Fe and Mn oxides (from 443 to 277 mg kg−1) fractions. Citric acid could efficiently facilitate assisted phytoextraction techniques.

An Assessment of Lithium Resources

Se hace un estudio de los recursos de una sustancia estratégica para la UE, a fin de orientar las investigaciones para un incremento de reservas que garanticen el abastecimiento de esta materia prima de gran demanda

Transit Use by Young People in Times of Financial Austerity: A Cause of Equity Concern?

This study investigates the effect of price and travel time fairness and spatial equity in transit provision on the perceived transit service quality, willingness to pay, and habitual frequency of use. Based on the theory of planned behavior, we developed a web-based questionnaire for revealed preferences data collection. The survey was administered among young people in Copenhagen and Lisbon to explore the transit perceptions and use under different economic and transit provision conditions. The survey yielded 499 questionnaires, analyzed by means of structural equation models. Results show that higher perceived fairness relates positively to higher perceived quality of transit service and higher perceived ease of paying for transit use. Higher perceived spatial equity in service provision is associated with higher perceived service quality. Higher perceived service quality relates to higher perceived ease of payment, which links to higher frequency of transit use.

Linked Data for sharing, discovery and re-use of Language Resources at a Web scale

Conferencia por invitación, impartida el 31 d mayo de 2014 en el Workshop on Language Technology Service Platforms: Synergies, Standards, Sharing at LREC2014

Políticas de esfuerzo combinado económico-laboral en la retención y atracción del conocimiento científico: un estudio del caso español

El objetivo de este trabajo es la aportación de un caso que evidencie la importancia de realizar esfuerzos tanto en el terreno económico como en el laboral para conseguir una adecuada retención y atracción del conocimiento científico. Para ello, se analizan los datos de un estudio que destaca estas cuestiones para un país como España, que necesita urgentemente mejorar su balance de movilidad investigadora. Los resultados confirman la importancia de la aplicación de estas medidas y las debilidades que presenta en este tipo de políticas el sistema nacional de investigación, desarrollo e innovación (I+D+i). Abstract: The goal of this paper is to disclose a case study which highlights the impor tance of realising effor ts at an economic and labour scale in order to reach an adequate retention and attraction of scientific knowledge. Although science has evolved during different periods through the flow of mankind and ideas, studies about international mobility of scientists are recent in time. It started mid XXth century with the brain drain phenomenon. To alleviate the loss of scientists, countries have disclosed different politics. Some countries like Singapore, Southern Korea, India and China have been successful in bringing scientists back home. Those countries have made huge effor ts in human resources investments and scientific infrastructures, so as to enforce their national R&D&I systems. Despite such experiences and despite the increasement in terms of evidences related with international scientific mobility, few studies and figures have been disclosed. The goal of this current work is to disclose data, which backs up the liability of such kind of politics that combine effor ts in economic and labour terms. For that reason, data has been analyzed from a study which highlights these key aspects for a country like Spain and which recently established a wide range of politics in order to attract scientists. Despite the increasement of financial resources, such politics have turned out unable to reach a proper balance in terms of mobility research. Such data as well as it analysis comes from the development of an annual survey to Spanish scientists during the period 2008- 2011. Based on sample data and analysis an expectations index for the coming year has been constructed. This compares the level of confidence which related the support and prestige of their national R&D&I systems in which they operate. Two groups where surveyed: young researchers which currently work in Spain and as a group are more likely to go working abroad and Spanish scientists who are currently working abroad. Samples were obtained for young researchers were the following: 2008 (217), 2009 (270), 2010 (390) and 2011 (610). In the case of Spanish scientists abroad, the following data were obtained: 2008 (218), 2009 (250), 2010 (241) and 2011 (167). Both groups assume simple random sampling, with a level of confidence of 95%. The results obtained confirm the importance of this combined effor t of labor and economic policies which presents weaknesses of Spanish national R&D&I systems and its application, so that Spain becomes a pole of excellence in terms of attraction and retention of scientific knowledge.