Suchergebnisse

Abstract
In aquatic ecosystems, animals are often exposed to a combination of stressors, including both natural and anthropogenic factors. Combined stressors may have additive or interactive effects on animals, either magnifying or reducing the effects caused by each stressor alone. Therefore, standardized bioassays can lead to overestimations or underestimations of the risk of toxicants if natural stressors are not bear in mind. The inclusion of natural stress in laboratory bioassays may help to extrapolate the laboratory results to ecosystems. This study assesses the effects of successive exposure to two sources of stress (high water conductivity and cadmium toxicity) on the behavior and survival of the aquatic snail Potamopyrgus antipodarum (Tateidae, Mollusca). I conducted a bioassay consisting on exposure to high conductivity (5000 mg NaCl/L, 7 days), followed by exposure to cadmium (0.03, 0.125, and 0.25 mg Cd/L for 7 days) and by a post-exposure period (7 days). Mortality, inactivity, and the time to start activity of active animals were monitored in each animal. In general, cadmium lethality was higher in animals previously undergoing high conductivity than in non-stressed ones. Previously stressed animals showed longer time to start activity, with a noticeable effect at the two highest cadmium concentrations. Animals submitted to the two highest cadmium concentration both, stressed and non-stressed, showed a moderate recovery during the post-exposure period. It is concluded that previous stress caused a worsening of the cadmium toxicity on the aquatic snail Potamopyrgus antipodarum, which is especially noticeable for mortality. However, there was no interactive effect between cadmium and conductivity on snail activity, which may be indicative of recovery after cadmium exposure regardless the previous stress suffered by the snails.

Dada la permanente búsqueda de maneras más eficientes y respetuosas con el medio ambiente, de propulsar la flota mundial, el presente trabajo tratará de dar una visión general del que parece uso creciente del metanol como combustible marino. Esta sustancia química, cuya demanda mundial se estima en 30 millones de toneladas métricas anuales, es uno de los productos químicos más consumidos. Bien es cierto que aunque aún es escaso su número, tenemos ejemplos de empresas constructoras de motores marinos o navieras, muy importantes, incluso líderes, en sus respectivos sectores, dentro del ámbito marino, que están apostando fuerte por esta tecnología, muy limpia en comparación a los combustibles tradicionales marinos, lo que podría ser indicativo de que en corto/medio plazo la propulsión con metanol sea más común. En este trabajo, se analizan aspectos referentes al cumplimiento de normas medio ambientales, sus características como sustancia química y como combustible, ventajas o inconvenientes de su uso, tipo de motores y buques en que está siendo utilizado, legislación al respecto, actualidad en la materia, y algunos otros aspectos de otras índoles. ; ABSTRACT: Given the ongoing search for more efficient and environmentally friendly ways to propel the global fleet, this work will seek to give an overview of what appears to be increasing use of methanol as marine fuel. This chemical, whose global demand is estimated at 30 million metric tons per year, is one of the most consumed chemicals. It is true that although their number is still low, we have examples of very important marine or shipping engine construction companies, even leaders, in their respective sectors, within the marine field, which are betting heavily on this technology, very clean compared to traditional marine fuels, which could be indicative that in the short/medium term methanol propulsion is more common. This work analyses aspects related to compliance with environmental standards, their characteristics as a chemical and as fuel, advantages or disadvantages of their use, type of engines and vessels in which it is being used, legislation in this regard, current in this area, and some other aspects of other nature. ; Máster en Ingeniería Marina

Peer reviewed ; Environmental acidity is a key parameter in Cultural Heritage conservation issues since it has a direct impact on degradation of both exposed and stored materials. Unfortunately, most of the acidity sensors now available are electrodes, which are not able to measure pH in gaseous phases and, therefore, are not suitable for measuring the environmental acidity of the air. This paper describes the development of an interface electronic system designed for the practical application and using of environmental acidity sensors prepared by the Sol–Gel procedure. These chemical sensors were investigated previously. They have optical response: their color changes reversibly depending on the pH of the surrounding environment (air). A simple portable unit with a wireless ZigBee interface has been designed and developed to measure the environmental acidity in museums, showcases, store and exhibition rooms and several Cultural Heritage buildings. Main achievements of the interface electronic system have focused, on the one hand, on conversion of the optical signal of sensors into an electric current and, on the other hand, on the computer interfacing to obtain quantitative data of environmental pH. Quantitative data are obtained through the calibration curve of sensors and the software designed for managing the whole system. The authors acknowledge partial funding of programs: Geomateriales (ref. S-2009/Mat-1629, Regional Government of Madrid), Consolider Ingenio 2010 (ref. TCP CSD2007-00058, Spanish Ministry of Science and Innovation), and project ref. HAR2012-30769 from the Spanish MINECO

Environmental acidity is a key parameter in Cultural Heritage conservation issues since it has a direct impact on degradation of both exposed and stored materials. Unfortunately, most of the acidity sensors now available are electrodes, which are not able to measure pH in gaseous phases and, therefore, are not suitable for measuring the environmental acidity of the air. This paper describes the development of an interface electronic system designed for the practical application and using of environmental acidity sensors prepared by the Sol–Gel procedure. These chemical sensors were investigated previously. They have optical response: their color changes reversibly depending on the pH of the surrounding environment (air). A simple portable unit with a wireless ZigBee interface has been designed and developed to measure the environmental acidity in museums, showcases, store and exhibition rooms and several Cultural Heritage buildings. Main achievements of the interface electronic system have focused, on the one hand, on conversion of the optical signal of sensors into an electric current and, on the other hand, on the computer interfacing to obtain quantitative data of environmental pH. Quantitative data are obtained through the calibration curve of sensors and the software designed for managing the whole system. ; The authors acknowledge partial funding of programs: Geomateriales (ref. S-2009/Mat-1629, Regional Government of Madrid), Consolider Ingenio 2010 (ref. TCP CSD2007-00058, Spanish Ministry of Science and Innovation), and project ref. HAR2012-30769 from the Spanish MINECO ; Peer reviewed