Download or read book Impacts of Selenium on the Biogeochemical Cycles of Mercury in Terrestrial Ecosystems in Mercury Mining Areas written by Hua Zhang and published by . This book was released on 2014-05-31 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Impacts of Selenium on the Biogeochemical Cycles of Mercury in Terrestrial Ecosystems in Mercury Mining Areas written by Hua Zhang and published by Springer Science & Business. This book was released on 2014-04-17 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt: From a new perspective, namely focusing on the interaction of selenium and mercury, this thesis provides new insights into traditional research on biogeochemical cycles of mercury in soil-plant interaction and associated human exposure and risks. The subject of this thesis is both valuable and timely, providing essential information not only on selenium-mercury interaction in the soil-plant system but also on how to assess the combined benefits and risk of co-exposure to mercury and selenium. This work also sheds light on future aspects regarding prevention, remediation and risk management for environmental mercury contamination. Presenting high-quality papers published in leading international SCI journals such as Environmental Health Perspectives and Environmental Science & Technology and having been recognized with the Special Award of Presidential Scholarship Award and Excellent Doctoral Dissertations Prize of the Chinese Academy of Sciences (CAS), this thesis offers a valuable resource for scientific communities, policy-makers and non-experts who are interested in this field. Dr. Hua Zhang works at the Norwegian Institute for Water Research (NIVA), Oslo, Norway.

Download or read book An Investigation of the Major Transformations and Loss Mechanisms of Mercury and Selenium in the Surface Ocean written by Brian P Dimento and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The importance of methylmercury (CH3Hg) photochemical degradation, an understudied process in marine ecosystems, was investigated in variety of coastal and oceanic waters from the northeastern U.S. as well as the Atlantic, Pacific and Arctic Oceans. Degradation rate constants ranged from 0.87 to 1.67 day-1,but did not correlate with the environmental parameters measured. Further experiments investigating the reaction mechanism observed little effect of nitrate, chloride, and bromide ions. CH3Hg loss per year due to photodegradation was modeled across latitudes from the Equator to the Arctic using water column integrated rates determined for coastal wetlands, estuaries and the open ocean. A global photochemical demethylation rate of 25.3 Mmol yr-1 was calculated, representing an important flux in the biogeochemical cycle of CH3Hg. Air-sea exchange of elemental mercury (Hg0), another important process in the biogeochemical cycle of Hg, was investigated on the U.S. GEOTRACES cruise in the Arctic Ocean in 2015. High resolution measurements of Hg0 in surface waters and the atmosphere were used to calculate evasional fluxes, and Hg concentrations determined in aerosols and precipitation were used to estimate atmospheric deposition. Overall, concentrations of dissolved Hg0 were near saturation in ice-free waters (32 ± 30 fM), but were highly enriched under contiguous ice (101 ± 98 fM, up to 544 fM). Predicted peaks in Hg0 evasion, although blocked by the sea ice barrier, were as high as 270 pmol m-2 h-1. From these estimates we can better predict the effect of a changing climate on Hg dynamics in the Arctic. The photochemical cycling of selenium (Se), an essential micronutrient, was also studied in marine waters. Inorganic Se(IV) and Se(VI) were found in nutrient-type distributions in samples collected during the Metzyme cruise on the equatorial Pacific Ocean in 2011. Photochemically mediated redox transformation pathways studied could not explain the enhanced concentrations of Se(IV) observed, indicating that a biological process is likely involved. Photodegradation was an important sink of dimethyl selenide ((CH3)2Se) in a variety of natural waters, with reaction rate constants ranging from 18.1 to 47.0 day-1. The global loss of (CH3)2Se due to photodegradation was estimated at 28.0 Gmol yr-1.

Download or read book Handbook of Ecotoxicology written by David J. Hoffman and published by CRC Press. This book was released on 2002-11-13 with total page 1316 pages. Available in PDF, EPUB and Kindle. Book excerpt: Completely revised and updated with 18 new chapters, this second edition includes contributions from over 75 international experts. Also, a Technical Review Board reviewed all manuscripts for accuracy and currency. Focusing on toxic substance and how they affect the ecosystems worldwide, the book presents methods for quantifying and measuring ecotoxicological effects in the field and in the lab, as well as methods for estimating, predicting, and modeling in ecotoxicology studies. This is the definitive reference for students, researchers, consultants, and other professionals in the environmental sciences, toxicology, chemistry, biology, and ecology - in academia, industry, and government.

Download or read book Ecological Impact of Selenium and Mercury on Two Insect Food Chains written by Peter Derek Jensen and published by . This book was released on 2006 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Global Biogeochemical Cycling of Mercury written by Noelle Eckley Selin and published by . This book was released on 2009 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury pollution poses global human health and environmental risks. Although mercury is naturally present in the environment, human activities, such as coal burning, have increased the amount of mercury cycling among the land, atmosphere, and ocean by a factor of three to five. Emitted to the atmosphere in its elemental form, mercury travels worldwide before oxidizing to a form that deposits to ecosystems. In aquatic systems, mercury can convert into methylmercury, a potent neurotoxin. People and wildlife are exposed to methylmercury as it bioaccumulates up the food chain. Mercury continues to circulate in the atmosphere, oceans, and terrestrial system for centuries to millennia before it returns to deep-ocean sediments. Areas of uncertainty in the global biogeochemical cycle of mercury include oxidation processes in the atmosphere, land-atmosphere and ocean-atmosphere cycling, and methylation processes in the ocean. National and international policies have addressed direct mercury emissions, but further efforts to reduce risks face numerous political and technical challenges.

Download or read book Global Biogeochemical Cycling of Mercury written by Noelle E. Selin and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury pollution poses global human health and environmental risks. Although mercury is naturally present in the environment, human activities, such as coal burning, have increased the amount of mercury cycling among the land, atmosphere, and ocean by a factor of three to five. Emitted to the atmosphere in its elemental form, mercury travels worldwide before oxidizing to a form that deposits to ecosystems. In aquatic systems, mercury can convert into methylmercury, a potent neurotoxin. People and wildlife are exposed to methylmercury as it bioaccumulates up the food chain. Mercury continues to circulate in the atmosphere, oceans, and terrestrial system for centuries to millennia before it returns to deep-ocean sediments. Areas of uncertainty in the global biogeochemical cycle of mercury include oxidation processes in the atmosphere, land-atmosphere and ocean-atmosphere cycling, and methylation processes in the ocean. National and international policies have addressed direct mercury emissions, but further efforts to reduce risks face numerous political and technical challenges.

Download or read book Occurrence of Selenium and Mercury in Surface Water Wind River Indian Reservation Wyoming 1995 written by Melanie L. Clark and published by . This book was released on 1996 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Coastal and Deep Ocean Pollution written by Andres Hugo Arias and published by CRC Press. This book was released on 2020-03-10 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the recent decades, social, political and academic endeavours have been made to improve environmental quality and reduce pollution. In particular, the ocean, sea and coastal areas show varying degrees of impact from the multiple human activities carried out in the terrestrial as well as in the aquatic environment. Ecology is a science which studies the relationship between organisms and the surrounding environment and in the modern era, the marine world is getting increasing attention. For centuries it has been the final reservoir of human garbage; later it became an oil farm with a concomitant increase of coastal population growth and unplanned growth of the fishing industry and the increasing use of sea routes for cargo transport and recreational uses (cruises). All this led to rising contamination with negative effects on biota and even human health. It is then imperative to know the current situation of the world's oceans: that is the main purpose of this book, to document at a glance the latest research in the field of ocean pollution.

Download or read book Aquatic Cycling of Selenium written by A. Dennis Lemly and published by . This book was released on 1987 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Papers Presented at the FAO UNEP WHO IOC IAEA Meeting on the Biogeochemical Cycle of Mercury in the Mediterranean Siena Italy 27 31 August 1984 written by and published by Food & Agriculture Org.. This book was released on 1986 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mercury as a Global Pollutant written by Donald B. Porcella and published by Springer. This book was released on 2014-08-23 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: ACKNOWLEDGEMENTS xiv PART I MERCURY AND HUMAN HEALTH B. WHEATLEY and S. PARADIS I Exposure of Canadian Aboriginal Peoples to Methylmercury 3-11 M. GIRARD and C. DUMONT I Exposure of James Bay Cree to Methylmercury during Pregnancy for the Years 1983-91 13-19 M. RICHARDSON, M. MITCHELL, S. COAD and R. RAPHAEL I Exposure to Mercury in Canada: A Multimedia Analysis 21-30 M. RICHARDSON, M. EGYED and D. J. CURRIE I Human Exposure to Mercury may Decrease as Acidic Deposition Increases 31-39 L. E. FLEMING, S. WATKINS, R. KADERMAN, B. LEVIN, D. R. AVYAR, M. BIZZIO, D. STEPHENS and J. A. BEAN I Mercury Exposure in Humans through Food Consumption from the Everglades of Florida 41-48 J. M. GEARHART, H. J. CLEWELL III, K. S. CRUMP, A. M. SHIPP and A. SILVERS I Pharmacokinetic Dose Estimates of Mercury in Children and Dose-Response Curves of Performance Tests in a Large Epidemiological Study 49-58 I. SKARE I Mass Balance and Systemic Uptake of Mercury Released from Dental Amalgam Fillings 59-67 J. DELLINGER, N. KMIECIK, S. GERSTENBERGER and H. NGU I Mercury Contamina tion of Fish in the Ojibwa Diet: I. Walleye Fillets and Skin-On versus Skin-Off Sampling 69-76 J. DELLINGER, L. MALEK and M. BEATTIE I Mercury Contamination of Fish in the Ojibwa Diet: II. Sensory Evoked Responses in Rats Fed Walleye 77-83 H. AKAGI, O. MALM, F. J. P. BRANCHES, Y. KINJO, Y. KASHIMA, J. R. D. GUIMARAES, R. B. OLIVEIRA, K. HARAGUCHI, W. C. PFEIFFER, Y.

Download or read book JV Task 96 Phase 2 Investigating the Importance of the Mercury Selenium Interaction written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to improve the understanding of the mercury issue, it is vital to study mercury's effects on selenium physiology. While mercury present in the environment or food sources may pose health risks, the protective effects of selenium have not been adequately considered in establishing regulatory policy. Numerous studies report that vulnerability to mercury toxicity is inversely proportional to selenium status or level. However, selenium status has not been considered in the development of the reference dosage levels for mercury exposure. Experimental animals fed low-selenium diets are far more vulnerable to mercury toxicity than animals fed normal selenium, and animals fed selenium-rich diets are even more resistant. Selenium-dependent enzymes in brain and endocrine tissues can be impaired by excessive mercury exposure, apparently because mercury has an extremely high binding affinity for selenium. When selenium becomes bound to mercury, it is unable to participate in the metabolic cycling of selenoprotein synthesis. Because of mercury-dependent impairments of selenoprotein synthesis, various antioxidant and regulatory functions in brain biochemistry are compromised. This report details a 2-year multiclient-funded research program designed to examine the interactions between mercury and selenium in animal models. The studies explored the effects of dietary intakes of toxic amounts of methylmercury and the protective effects of the normal dietary range of selenium in counteracting mercury toxicity. This study finds that the amounts of selenium present in ocean fish are sufficient to protect against far larger quantities of methylmercury than those present in typical seafoods. Toxic effects of methylmercury exposure were not directly proportional to mercury concentrations in blood, brain, or any other tissues. Instead, mercury toxicity was proportional to molar ratios of mercury relative to selenium. In order to accurately assess risk associated with methylmercury or mercury exposures, mercury-selenium ratios appear to be far more accurate and effective in identifying risk and protecting human and environmental health. This study also finds that methylmercury toxicity can be effectively treated by dietary selenium, preventing the death and progressive disabilities that otherwise occur in methylmercury-treated subjects. Remarkably, the positive response to selenium therapy was essentially equivalent regardless of whether or not toxic amounts of methylmercury were still administered. The findings of the Physiologically Oriented Integration of Nutrients and Toxins (POINT) models of the effects of mercury and selenium developed in this project are consistent with the hypothesis that mercury toxicity arises because of mercury-dependent inhibition of selenium availability in brain and endocrine tissues. This appears to occur through synergistic effects of mercury-dependent inhibition of selenium transport to these tissues and selective sequestration of the selenium present in the tissues. Compromised transport of selenium to the brain and endocrine tissues would be particularly hazardous to the developing fetus because the rapidly growing tissues of the child have no selenium reserves. Therefore, maternal consumption of foods with high mercury-selenium ratios is hazardous. In summation, methylmercury exposure is unlikely to cause harm in populations that eat selenium-rich diets but may cause harm among populations that consume certain foods that have methylmercury present in excess of selenium.

Download or read book Selenium Assessment in Aquatic Ecosystems written by A. Dennis Lemly and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Selenium is a naturally occurring trace element that can become concentrated and released by industrial, agricultural, petrochemical and mining activities. At concentrated levels it is toxic and has polluted ecosystems around the world. This book will serve as a comprehensive practical handbook for everyone dealing with selenium in aquatic environments. It offers field-tested approaches and methods for assessment and water quality management. Using his twenty-year experience, the author discusses the effects of selenium on fish and bird populations and presents guidelines for identifying sources of pollution, interpreting selenium concentrations, assessing hazardous conditions, setting water quality criteria and ecosystem loading limits (TMDLs). He also includes a procedure for setting environmentally safe limits that ensure compliance with EPA regulations. Selenium Assessment in Aquatic Ecosystems will interest field scientists, natural resource managers, risk assessors and environmental planners.

Download or read book Mercury Biogeochemical Cycling and Processes Implications for Human and Ecosystem Health written by and published by . This book was released on 2014 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ecosystem Responses to Mercury Contamination written by Reed Harris and published by CRC Press. This book was released on 2007-03-05 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: As rising levels of mercury in the environment pose an increasing threat of toxicity to humans and wildlife, several laws already call for industries to reduce mercury emissions at the source. Ecosystem Responses to Mercury Contamination: Indicators of Change outlines the infrastructure and methods needed to measure, monitor, and regulate the conce

Download or read book Pollution Abstracts written by and published by . This book was released on 1996 with total page 858 pages. Available in PDF, EPUB and Kindle. Book excerpt: Indexes material from conference proceedings and hard-to-find documents, in addition to journal articles. Over 1,000 journals are indexed and literature published from 1981 to the present is covered. Topics in pollution and its management are extensively covered from the standpoints of atmosphere, emissions, mathematical models, effects on people and animals, and environmental action. Major areas of coverage include: air pollution, marine pollution, freshwater pollution, sewage and wastewater treatment, waste management, land pollution, toxicology and health, noise, and radiation.