خيارات البحث
النتائج 4291 - 4300 من 4,309
Maternal transfer of dioxin-like compounds in artificially matured European eels النص الكامل
2017
Freese, Marko | Sühring, Roxana | Marohn, Lasse | Pohlmann, Jan-Dag | Wolschke, Hendrik | Byer, Jonathan | Alaee, Mehran | Ebinghaus, Ralf | Hanel, Reinhold
Several eel species of the genus Anguilla are considered endangered due to a severe decline in recruitment. Up to now, the reasons for this threatening development are not fully understood. The eel's highly specialized biology can lead to explicitly high accumulation of globally distributed organic lipophilic contaminants during its continental life. Because of this and due the particular toxicological sensitivity of early life stages of oviparous organisms towards dioxin-like compounds, it is crucial to improve our understanding concerning toxicokinetics and maternal transfer of organic contaminants in eels. This study presents analytical data on maternal transfer of dioxin-like (dl) compounds in relevant tissue samples taken from artificially matured and non-matured European silver eels (Anguilla anguilla) from German inland waters using gas chromatography coupled with mass spectrometry (GC/MS) and high-resolution mass spectrometry (GC/HRMS). Detected concentrations revealed a lipid-driven transfer of targeted compounds from muscle-fat-reserves to gonads and eggs respectively, with no distinct preferences concerning the chlorination degree of targeted compounds. Dl-PCBs were shown to contribute the major share of toxicity equivalents found in analysed eel tissues. Maternal muscle tissue to egg concentration ratios in wet weightebased samples had a mean of 6.95 ~c 1.49 in accordance with the differences in total lipid content in the respective body matrices. Dioxins and furans in analysed samples were (from a toxicological point of view) of less relevance. Furthermore it was shown that muscle concentrations in silver eels could be used in future assessments to make conservative predictions for expected egg concentrations in female eels.
اظهر المزيد [+] اقل [-]The effects of ocean acidification and a carbon dioxide capture and storage leak on the early life stages of the marine mussel Perna perna (Linneaus, 1758) and metal bioavailability النص الكامل
2017
Szalaj, D | De Orte, Manoela R | Goulding, T A | Medeiros, I D | DelValls, T Angel | Cesar, A
The study assesses the effects of carbon dioxide capture and storage (CCS) leaks and ocean acidification (OA) on the metal bioavailability and reproduction of the mytilid Perna perna. In laboratory-scale experiments, CCS leakage scenarios (pH 7.0, 6.5, 6.0) and one OA (pH 7.6) scenario were tested using metal-contaminated sediment elutriates and seawater from Santos Bay. The OA treatment did not have an effect on fertilisation, while significant effects were observed in larval-development bioassays where only 16 to 27 % of larva developed normally. In treatments that simulated CO2 leaks, when compared with control, fertilisation success gradually decreased and no larva developed to the D-shaped stage. A fall in pH increased the bioavailability of metals to marine mussels. Larva shell size was significantly affected by both elutriates when compared with seawater; moreover, a significant difference occurred at pH 6.5 between elutriates in the fertilisation bioassay.
اظهر المزيد [+] اقل [-]Estimación de patrones de conducción en una vía del sur de Cali para el cálculo de las emisiones atmosféricas con el modelo IVE النص الكامل
2017
González Naranjo, Daniel Mauricio | Lasso Palacios, Ana Paola
La contaminación atmosférica es un problema mundial responsable de muertes prematuras y el aumento de costos sociales. El deterioro de la calidad del aire en zonas urbanas se asocia entre otras a emisiones de fuentes móviles en carretera. Para controlar estas fuentes, se requiere estimar las emisiones contaminantes. Una herramienta desarrollada para este fin es el modelo IVE que establece las emisiones de los vehículos, según condiciones locales representadas en los patrones de conducción. Aunque este modelo se ha implementado a nivel mundial, el establecimiento de los patrones de conducción es una limitante en su aplicación. En este sentido, buscando aportar información que mejore los estimativos de las emisiones vehiculares en Cali, este proyecto estableció los patrones de conducción al sur de la ciudad. Se determinó una ruta de 15.69 km que cubrió las vías de mayor tráfico vehicular en diferentes franjas horarias (mañana, mediodía y noche). Con los patrones establecidos, se estimaron emisiones de CO, NOx, SO2 y PM10. En la franja de la mañana y la noche se encontró una reducción de las emisiones estimadas con los patrones para Cali en comparación con los de Bogotá para todos los vehículos excepto las motos. No obstante, en la franja del mediodía las camionetas y los buses incrementaron las emisiones. Estos datos mostraron que, aunque las variaciones suelen encontrarse por debajo del 30% es necesario determinar los patrones de conducción para disminuir las incertidumbres en el manejo de la información para la gestión de la calidad del aire en cada ciudad | Valle del Cauca, Colombia | Proyecto de grado (Ingeniero Ambiental)-- Universidad Autónoma de Occidente, 2017. | Pregrado | Ingeniero(a) Ambiental
اظهر المزيد [+] اقل [-]Análisis de las mediciones de pm 10 para el primer semestre del año 2017 en la estación de monitoreo del municipio de Nobsa con respecto a la norma de calidad del aire | Analysis of pm 10 measurements for the first semester of 2017 in the monitoring station of the municipality of Nobsa with respect to the air quality standard النص الكامل
2017
Hernández Corredor, Cristian Daniel | Riaño, Felipe
14 páginas : gráficos. | Dada la problemática que presenta el municipio de Nobsa al poseer tanto en su perímetro urbano como rural diferentes fuentes de contaminación ambiental bastantes importantes y buscando aprovechar al máximo los recursos existentes en el mismo que permiten monitorear los niveles de PM10, se solicitó a Corpoboyaca quien es la entidad encargada del manejo y control de la información de las muestras correspondientes a las emisiones de PM10 tomadas por la estación de monitoreo ubicada en las instalaciones del cuerpo de bomberos del casco urbano del municipio de Nobsa, que nos facilitara una copia de las información con el fin de realizar un análisis comparativo detallado. El periodo de tiempo de la información evaluada corresponde a los meses de enero a junio de 2017, en la cual se hizo una revisión del cumplimiento de las muestras obtenidas de la estación durante cada día, y una comparación de estas con el valor máximo permitido por la norma de calidad del aire establecida en su oportunidad por el Ministerio de ambiente, vivienda y desarrollo territorial en la Resolución 610 del 24 de marzo de 2010 además de un estudio de la información apoyado en un análisis estadístico con graficas de los datos que reflejan el estado actual de la contaminación del aire en el municipio | Given the problems presented by the municipality of Nobsa by having both important environmental pollution sources in its urban and rural perimeter and seeking to make the most of the existing resources that allow the monitoring of Pm 10 levels, corpoboyaca was requested the entity in charge of the handling and control of the information of the samples corresponding to the PM 10 emissions taken by the monitoring station located in the facilities of the fire department in the urban area municipality of Nobsa wich will provide us with a copy of information with in order to perform a detailed comparative analysis.
اظهر المزيد [+] اقل [-]Phenology, accumulation period and climate change: case-study in Germany النص الكامل
2017
Grünhage, Ludger | Bender, Jürgen
Ecotoxicology in Latin America
2017
Araújo, Cristiano V. M. | Shinn, Candida Helena
Review of ICP forest publications (06/2016-05/2017) النص الكامل
2017
Prescher, Anne-Katrin | Schmitz, Andreas | Michel, Alexa K.
Spatial variation of atmospheric deposition in Europe in 2015 النص الكامل
2017
Schmitz, Andreas | Waldner, Peter | Verstraeten, Arne | Hansen, Karin
Monitoring the atmospheric deposition to forests is a prerequisite for understanding forest ecosystem processes and an important contribution for evaluating the spatio-temporal trends of air pollution. In this report, we present the annual throughfall deposition of eutrophying, acidifying and buffering components on ICP Forests Level II plots in 2015. The nitrogen (N) compounds nitrate (NO3-) and ammonium (NH4 +) are the main drivers of eutrophication and also contribute to acidification. High deposition rates to forests (throughfall deposition > 8 kg N ha-1 yr-1) were measured at several plots in central Europe (Belgium, Germany) but also in the Czech Rupublic, Denmark and southern Sweden. Low depositions rates have been reported primarily in northern Europe. Sulfate (SO4 2-) has been the most important driver of soil acidification. High deposition of SO4 2- (throughfall deposition > 8 kg SO4 2--S ha-1 yr-1) was still found in central Europe (e.g. Belgium, Germany) as well as in the Czech Republic. In addition, high sulfate deposition occurred in southern Europe (Italy, Greece) which is probably related to natural sources. Similarly, high calcium (Ca2+) deposition across southern Europe is likely related to contributions from Saharan Dust. The spatial pattern of magnesium (Mg2+) deposition is mainly dominated by marine sources. Both Ca2+and Mg2+ are macronutrients and act as buffers against acidification. The overall spatial patterns of deposition of eutrophying, acidifying and buffering substances in 2015 remained similar to results from the previous years.
اظهر المزيد [+] اقل [-]Trends in foliar nitrogen and phosphorus concentrations and ratios since 2000 النص الكامل
2017
Sanders, Tanja G. | Schmitz, Andreas | Edinger, Jens