1000 resultados para environment.


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The performance of a 3 × 3 MIMO system using RoF-enabled DAS technology is experimentally investigated in a Non-Line-Of-Sight environment. Reduced spatial correlation and improved SNR are achieved due to the larger antenna separation. © 2011 OSA.

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The assessment of emerging risks in the aquatic environment is a major concern and focus of environmental science (Daughton and Ternes, 1999). One significant class of chemicals that has received relatively little attention until recently are the human use pharmaceuticals. In 2004, an estimated 2.6 billion prescriptions were written for the top 300 pharmaceuticals in the U.S. (RxList, 2005). Mellon et al. (2001) estimated that 1.4 million kg of antimicrobials are used in human medicine every year. The use of pharmaceuticals is also estimated to be on par with agrochemicals (Daughton and Ternes, 1999). Unlike agrochemicals (e.g., pesticides) which tend to be delivered to the environment in seasonal pulses, pharmaceuticals are continuously released through the use/excretion and disposal of these chemicals, which may produce the same exposure potential as truly persistent pollutants. Human use pharmaceuticals can enter the aquatic environment through a number of pathways, although the main one is thought to be via ingestion and subsequent excretion by humans (Thomas and Hilton, 2004). Unused pharmaceuticals are typically flushed down the drain or wind up in landfills (Jones et al. 2001).

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Technological innovation has made it possible to grow marine finfish in the coastal and open ocean. Along with this opportunity comes environmental risk. As a federal agency charged with stewardship of the nation’s marine resources, the National Oceanic and Atmospheric Administration (NOAA) requires tools to evaluate the benefits and risks that aquaculture poses in the marine environment, to implement policies and regulations which safeguard our marine and coastal ecosystems, and to inform production designs and operational procedures compatible with marine stewardship. There is an opportunity to apply the best available science and globally proven best management practices to regulate and guide a sustainable United States (U.S.) marine finfish farming aquaculture industry. There are strong economic incentives to develop this industry, and doing so in an environmentally responsible way is possible if stakeholders, the public and regulatory agencies have a clear understanding of the relative risks to the environment and the feasible solutions to minimize, manage or eliminate those risks. This report spans many of the environmental challenges that marine finfish aquaculture faces. We believe that it will serve as a useful tool to those interested in and responsible for the industry and safeguarding the health, productivity and resilience of our marine ecosystems. This report aims to provide a comprehensive review of some predominant environmental risks that marine fish cage culture aquaculture, as it is currently conducted, poses in the marine environment and designs and practices now in use to address these environmental risks in the U.S. and elsewhere. Today’s finfish aquaculture industry has learned, adapted and improved to lessen or eliminate impacts to the marine habitats in which it operates. What progress has been made? What has been learned? How have practices changed and what are the results in terms of water quality, benthic, and other environmental effects? To answer these questions we conducted a critical review of the large body of scientific work published since 2000 on the environmental impacts of marine finfish aquaculture around the world. Our report includes results, findings and recommendations from over 420 papers, primarily from peer-reviewed professional journals. This report provides a broad overview of the twenty-first century marine finfish aquaculture industry, with a targeted focus on potential impacts to water quality, sediment chemistry, benthic communities, marine life and sensitive habitats. Other environmental issues including fish health, genetic issues, and feed formulation were beyond the scope of this report and are being addressed in other initiatives and reports. Also absent is detailed information about complex computer simulations that are used to model discharge, assimilation and accumulation of nutrient waste from farms. These tools are instrumental for siting and managing farms, and a comparative analysis of these models is underway by NOAA.

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Innovative research relating oceans and human health is advancing our understanding of disease-causing organisms in coastal ecosystems. Novel techniques are elucidating the loading, transport and fate of pathogens in coastal ecosystems, and identifying sources of contamination. This research is facilitating improved risk assessments for seafood consumers and those who use the oceans for recreation. A number of challenges still remain and define future directions of research and public policy. Sample processing and molecular detection techniques need to be advanced to allow rapid and specific identification of microbes of public health concern from complex environmental samples. Water quality standards need to be updated to more accurately reflect health risks and to provide managers with improved tools for decision-making. Greater discrimination of virulent versus harmless microbes is needed to identify environmental reservoirs of pathogens and factors leading to human infections. Investigations must include examination of microbial community dynamics that may be important from a human health perspective. Further research is needed to evaluate the ecology of non-enteric water-transmitted diseases. Sentinels should also be established and monitored, providing early warning of dangers to ecosystem health. Taken together, this effort will provide more reliable information about public health risks associated with beaches and seafood consumption, and how human activities can affect their exposure to disease-causing organisms from the oceans.

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EXTRACT (SEE PDF FOR FULL ABSTRACT): The horizontal and vertical distribution of three dissolved trace gases, namely molecular hydrogen, carbon monoxide, and methane, was measured in coastal and oceanic areas. Atmospheric concentrations of these gases were measured both at locations influenced by nearby human activity, and in areas far removed from these inputs.