939 resultados para ANTHROPOGENIC LEAD


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The U.S. Geological Survey (USGS) is committed to providing the Nation with credible scientific information that helps to enhance and protect the overall quality of life and that facilitates effective management of water, biological, energy, and mineral resources (http://www.usgs.gov/). Information on the Nation’s water resources is critical to ensuring long-term availability of water that is safe for drinking and recreation and is suitable for industry, irrigation, and fish and wildlife. Population growth and increasing demands for water make the availability of that water, now measured in terms of quantity and quality, even more essential to the long-term sustainability of our communities and ecosystems. The USGS implemented the National Water-Quality Assessment (NAWQA) Program in 1991 to support national, regional, State, and local information needs and decisions related to water-quality management and policy (http://water.usgs.gov/nawqa). The NAWQA Program is designed to answer: What is the condition of our Nation’s streams and ground water? How are conditions changing over time? How do natural features and human activities affect the quality of streams and ground water, and where are those effects most pronounced? By combining information on water chemistry, physical characteristics, stream habitat, and aquatic life, the NAWQA Program aims to provide science-based insights for current and emerging water issues and priorities. From 1991-2001, the NAWQA Program completed interdisciplinary assessments and established a baseline understanding of water-quality conditions in 51 of the Nation’s river basins and aquifers, referred to as Study Units (http://water.usgs.gov/nawqa/studyu.html).

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“Nearly all men can stand adversity, but if you want to test a man’s character give him power.” That quote, by my hero Abraham Lincoln, is one I think all leaders should remember and reflect on regularly in their life, and so I pass it on to each of you. I wish each member of this LEAD group the character to use power wisely, with compassion and integrity, and a strong-sense of justice and fair play.

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Good morning. I am delighted to be with you here this morning to offer my congratulations and my best wishes as you complete the LEAD program. This is a wonderful and significant accomplishment, and I certainly hope you all are celebrating and savoring it. I look forward with enthusiasm to watching your future contributions as leaders in agriculture, in your local communities, in Nebraska, and in our global community. I'd like to start my remarks this morning with one question: How many people in this room have ridden an elephant? Show of hands?

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A CURRENT EXAMINATION OF DIETARY INTAKES OF FIBER, CALCIUM, IRON, AND ZINC AND THEIR RELATIONSHIP TO BLOOD LEAD LEVELS IN U.S. CHILDREN AGED 1-5 YEARS Stephanie Ann Melchert, M.S. University of Nebraska, 2010 Adviser: Kaye Stanek Krogstrand The effect of lead on the health and well-being of those exposed has been well documented and many efforts have been made to reduce exposure of lead to the United States population. Despite these efforts, many studies have documented cognitive impairments and behavioral problems in children with even low levels of lead in their blood. Previous studies have suggested that a proper diet may have a role in the prevention of elevated blood lead levels in children. The objective of this study was to determine if there was an inverse correlation of blood lead levels (BLL) in children to their dietary intakes of fiber, calcium, iron, and zinc considering low levels of lead exposure. This study examined 1019 children in the National Health and Nutrition Examination Survey (NHANES) conducted from 2005-2006. Data were analyzed using Spearman’s rank correlations to correlate continuous variables to BLL in children and independent samples t-tests were used to compare mean blood lead levels of categorical variables. Results indicate that BLL in children is significantly correlated with and weight, recumbent length/standing height, dietary fiber intake and continine, a marker of cigarette smoke exposure. BLL was not significantly correlated with calcium, iron, zinc, or vitamin C. A significant difference was found in the mean BLL of children who took supplements, lived in smoking homes, as well as those who lived in homes built before 1978. Overall, this study shows that children living in homes built before 1978 remain at greater risk for lead exposure, and adequate dietary fiber intake may provide benefits to children who are exposed to lead.

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Black bears (Ursus americanus) forage selectively in natural environments. To determine if bears also forage selectively for anthropogenic resources we analyzed data on vehicles broken into by bears from Yosemite National Park, California. We classified vehicles into 9 categories based on their make and model and collected data on use (2001–2007) and availability (2004–2005). From 2001 to 2007 bears broke into 908 vehicles at the following rates: minivan (26.0%), sport–utility vehicle (22.5%), small car (17.1%), sedan (13.7%), truck (11.9%), van (4.2%), sports car (1.7%), coupe (1.7%), and station wagon (1.4%). Only use of minivans (29%) during 2004–2005 was significantly higher than expected (7%). We discuss several competing hypotheses about why bears selected minivans.

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Thank you for inviting us to share with you some information about the Institute of Agriculture and Natural Resources, and what we are doing for Nebraska. As a stakeholder in Nebraska's land-grant university, you and every other Nebraskan have every right at any time to ask us what we've done for you and your neighbors lately. We welcome the question. There is so much excellent work being accomplished on this campus and throughout Nebraska that I am delighted each time I have the opportunity to talk about it. The biggest problem I find is stopping - there's always so much more to say - than there is time to say it in!

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Folks, we're just delighted to have you on campus with us, and I greatly appreciate this opportunity to speak with you.

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Good afternoon, everyone. Those of us representing the Institute of Agriculture and Natural Resources are pleased to be here with you today. We welcome you to IANR Shout It Out, the exciting Institute of Agriculture and Natural Resources game that allows you to test your IANR and Nebraska knowledge, learn exciting new facts, and most importantly of all win prizes!

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Let me begin today by offering my congratulations to each of you who is a member of this new LEAD class. You are embarking upon a truly exciting, rewarding opportunity, important to both you and Nebraska. Our state needs good leaders, people dedicated to keeping our organizations, communities, and Nebraska strong, and moving forward. We need leaders of courage and compassion, able to think clearly, assess information, formulate a plan, and adjust that plan as needed. We need leaders who work toward a common good.

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Mass mortalities due to disease outbreaks have recently affected major taxa in the oceans. For closely monitored groups like corals and marine mammals, reports of the frequency of epidemics and the number of new diseases have increased recently. A dramatic global increase in the severity of coral bleaching in 1997-98 is coincident with high El Niño temperatures. Such climate-mediated, physiological stresses may compromise host resistance and increase frequency of opportunistic diseases. Where documented, new diseases typically have emerged through host or range shifts of known pathogens. Both climate and human activities may have also accelerated global transport of species, bringing together pathogens and previously unexposed host populations.

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The present work is focused on the study of a seasonal anthropogenic influence on the beach of Itamambuca (Ubatuba, SP, Brazil) carried out using Atherinella brasiliensis as biomonitor. In total 84 fish were caught between July 2004 and February 2005 in different locations at the beach and inside the Itamambuca river. The fish were pooled according to catch and their musculature was analyzed by Particle-Induced X-ray Emission (PIXE) and Rutherford Backscattering (RBS) techniques. While the concentration of light (matrix) elements like C and O were obtained using the RBS technique, major (Na, Mg, P, S, Cl, K and Ca) and trace (Si, Al, Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br and Sr) elements were measured by PIXE. The results show that differences were observed for several elemental concentrations of fish tissue between high season (spring-summer) and low season (winter-fall), indicating that increased human activity in the beach during high season may have some impact on the beach ecosystem. The role of the water salinity in the results is also discussed. (C) 2009 Elsevier B.V. All rights reserved.

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The Cananeia-Iguape system, SE Brazil, consists of a complex of lagoonal channels, located in a United Nations Educational, Scientific and Cultural Organization (UNESCO) Biosphere Reserve. Nevertheless, important environmental changes have occurred in approximately the last 150 yrs due to the opening of an artificial channel, the Valo Grande, connecting the Ribeira de Iguape River to the lagoonal system. Our objective is to assess the historical record of the uppermost layers of the sedimentary column of the lagoonal system in order to determine the history of environmental changes caused by the opening of the artificial channel. In this sense, an integrated geochemical-faunal approach is used. The environmental changes led significant modifications in salinity, in changes of the depositional patterns of sediments and foraminiferal assemblages (including periods of defaunation), and, more drastically, in the input of heavy metals to the coastal environment. The concentrations Pb in the core analyzed here were up to two times higher than the values measured in contaminated sediments from the Santos estuary, the most industrialized coastal zone in Brazil.

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OBJECTIVE: To estimate the prevalence of lead poisoning in children and to identify associated factors, as well as possible local sources of contamination. METHODS: A cross-sectional prevalence study conducted in 2006 with a random sample of 97 children age zero to five years from a neighborhood in Porto Alegre, Southern Brazil. Blood lead levels were measured and a questionnaire administered to collect information on sociodemographics, recycling and dwelling. A preliminary environmental evaluation was carried out with direct analysis of soil and indirect analysis of air pollution with bioindicators to identify possible sources of contamination. To analyze lead concentrations from the different collection sites, for each type of material studied, ANOVA was performed with a Brown-Forsythe adjustment for heteroscedasticity and with Dunnett's T3 procedure for multiple comparisons of unequal variances. RESULTS: Blood lead levels >= 10.0 mu g/dL was found in 16.5% of children. Recycling of waste at home, low father's education level, and increased age of children were associated with increase blood lead levels. High lead levels were found in soil, and there was little indication of lead air pollution. CONCLUSIONS: A high prevalence of lead poisoning was identified, and the potential sources of contamination in this community appear related to waste recylcing activities. Studies should be conducted with other populations of Brazilian children and evaluate potential sources of local and general contamination, to accurately characterize this issue in Brazil.

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The development of an electroanalytical method for simultaneous determination of copper and lead ions in sugar cane spirit (cachaca) using carbon paste electrode modified with ascorbic acid and carbon nanotubes (CPE-AaCNT) is described. Squarewave voltammetry (SWV) with anodic stripping was employed, and this technique was optimized with respect to the following parameters: frequency (50 Hz), amplitude (100 mV) and scan increment (9 mV). The analytical curves were linear in the range from 0.0900 to 7.00 mg L-1 for lead and copper. The limits of detection were 48.5 and 23.9 mu g L-1 for lead and copper, respectively. The developed method was applied to the simultaneous determination of copper and lead in five commercial samples of sugar cane spirit. The results were in good agreement with those obtained by F AAS/GF AAS (flame atomic absorption spectrometry/graphite furnace atomic absorption spectrometry) and showed that CPE-AaCNT can be successfully employed in the simultaneous determination of these metals in real sugar cane spirit samples.

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Assessment of the suitability of anthropogenic landscapes for wildlife species is crucial for setting priorities for biodiversity conservation. This study aimed to analyse the environmental suitability of a highly fragmented region of the Brazilian Atlantic Forest, one of the world's 25 recognized biodiversity hotspots, for forest bird species. Eight forest bird species were selected for the analyses, based on point counts (n = 122) conducted in April-September 2006 and January-March 2009. Six additional variables (landscape diversity, distance from forest and streams, aspect, elevation and slope) were modelled in Maxent for (1) actual and (2) simulated land cover, based on the forest expansion required by existing Brazilian forest legislation. Models were evaluated by bootstrap or jackknife methods and their performance was assessed by AUC, omission error, binomial probability or p value. All predictive models were statistically significant, with high AUC values and low omission errors. A small proportion of the actual landscape (24.41 +/- 6.31%) was suitable for forest bird species. The simulated landscapes lead to an increase of c. 30% in total suitable areas. In average, models predicted a small increase (23.69 +/- 6.95%) in the area of suitable native forest for bird species. Being close to forest increased the environmental suitability of landscapes for all bird species; landscape diversity was also a significant factor for some species. In conclusion, this study demonstrates that species distribution modelling (SDM) successfully predicted bird distribution across a heterogeneous landscape at fine spatial resolution, as all models were biologically relevant and statistically significant. The use of landscape variables as predictors contributed significantly to the results, particularly for species distributions over small extents and at fine scales. This is the first study to evaluate the environmental suitability of the remaining Brazilian Atlantic Forest for bird species in an agricultural landscape, and provides important additional data for regional environmental planning.