Download or read book The Seasonal and Spatial Variations of Mercury Methylation and Methylmercury Decomposition in an Oligotrophic Northern Wisconsin Lake written by Eric T. Korthals and published by . This book was released on 1986 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: The formation of methylmercury represents a potentially serious problem in aquatic ecosystems because of its toxicity and accumulation in aquatic biota. Elevated levels of mercury in edible fish have recently been reported for several lakes in Northern Wisconsin. The majority of mercury in fish tissue is in the methylated form, suggesting that biological mercury methylation is a key process regulating mercury levels in fish. Numerous studies have examined mercury methylation in aquatic ecosystems but most have addressed only net rates of methylmercury production. The net amount of methylmercury produced in the aquatic environment is dependent on both methylation and demethylation. Recent studies have examined the effects of pH on mercury methylation and demethylation in several lakes in Canada and Northern Wisconsin. However, little else is known about the relative rates of these simultaneous processes in aquatic ecosystems. The purpose of this study was to examine where and when the potential for methylation was the greatest in Lake Clara; to examine the products of microbial demethylation; and to examine the effects of acidification on methylation and demethylation. Microbial mercury methylation and methylmercury decomposition were examined in Lake Clara, an oligotrophic Northern Wisconsin seepage lake, using 203Hg(N03)2 and 14cH3Hgi, respectively. The primary sites for mercury methylation in Lake Clara were in the surficial sediments of the backwater area and the littoral-profundal transitionary zone. Mercury methylation in surficial sediments was greatest from mid-July through September. The potential for methylation in the water column and attached microbial communities was low; whereas, demethylation activity was substantially greater. Thus, the net rate of methylmercury production may be significantly affected by demethylation activity.

Download or read book Applied and Environmental Microbiology written by and published by . This book was released on 1987 with total page 812 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1988 with total page 1198 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1988 with total page 1212 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Abstracts of the Annual Meeting of the American Society for Microbiology written by American Society for Microbiology. Annual Meeting and published by . This book was released on 1986 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Environmental Toxicology and Chemistry written by and published by . This book was released on 1999 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Seasonal and Spatial Variations in Methylmercury in the Water Column of Sulfate Impacted Lakes written by Logan Bailey and published by . This book was released on 2014 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Journal of the Minnesota Academy of Science written by and published by . This book was released on 1989 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Pollution Abstracts written by and published by . This book was released on 1988-05 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Acidification of Mercury Methylation and Volatilization in an Oligotrophic Northern Wisconsin Lake written by Robert J. Steffan and published by . This book was released on 1984 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of experimental acidification on mercury methylation and volatilization were measured in sediment, water, and attached microbial communities (on artificial substrates) from an acid-susceptible Wisconsin lake. This research was initiated to determine potential mechanisms causing elevated mercury concentrations in biota of low pH waters. Methylation and volatilization rates were quantified by incubating samples with 203Hg(NO3) and measuring the formation of CH3 203HG+ and volatile 203Hg species, respectively. The effects of acidification on these processes were assessed by experimental acidification of samples with either HCl or H2S04. Methylation was greatest in surficial sediments (0-10 cm) from the profundal zone of the lake, and significantly less (p

Download or read book Mercury Levels in Walleyes from Wisconsin Lakes of Different Water and Sediment Chemistry Characteristics written by Richard C. Lathrop and published by . This book was released on 1989 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Spatial and Temporal Variation in Mercury Methylation in Sediment and Water of Farmington Bay of the Great Salt Lake Utah written by Abigail Rudd and published by . This book was released on 2010 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sediment Methylmercury Concentrations and Production Rates in Coastal Wetlands of Chequamegon Bay WI Lake Superior written by Jacob Ogorek and published by . This book was released on 2009 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury in Lake Superior is understudied, and (1) geochemical factors in sediments that influence sedimentary methylmercury concentrations and (2) key habitats for methylmercury production are unclear. The primary methylmercury source in aquatic systems is typically inorganic mercury methylation by sulfate reducing bacteria (SRB). Mercury methylation is generally greatest in wetland sediments, and is mediated by inorganic mercury bioavailability and SRB activity, both of which are strongly influenced by sulfidic compounds and organic matter. We hypothesize that Lake Superior coastal wetlands are important sites for methylmercury production, and sediment methylmercury correlates with sedimentary geochemical factors such as inorganic mercury, sulfide/sulfate, organic matter, and mercury methylation potential. We measured sediment methyl and total mercury concentrations, mercury methylation potential (via isotopic mercury additions), organic matter, sulfide, and sulfate in three coastal wetlands (two of which are located at the mouth of a tributary) and one open-water site in Chequamegon Bay (Lake Superior). Sediment mercury levels were relatively low, with the highest concentrations measured in coastal wetlands, particularly when associated with a tributary. We found methylmercury levels were correlated with multiple geochemical parameters, and it appears that sediment organic matter is the primary driving force of SRB activities leading to methylmercury production.

Download or read book Biogeochemistry of Wetlands written by K. Ramesh Reddy and published by CRC Press. This book was released on 2022-09-10 with total page 926 pages. Available in PDF, EPUB and Kindle. Book excerpt: The globally important nature of wetland ecosystems has led to their increased protection and restoration as well as their use in engineered systems. Underpinning the beneficial functions of wetlands are a unique suite of physical, chemical, and biological processes that regulate elemental cycling in soils and the water column. This book provides an in-depth coverage of these wetland biogeochemical processes related to the cycling of macroelements including carbon, nitrogen, phosphorus, and sulfur, secondary and trace elements, and toxic organic compounds. In this synthesis, the authors combine more than 100 years of experience studying wetlands and biogeochemistry to look inside the black box of elemental transformations in wetland ecosystems. This new edition is updated throughout to include more topics and provide an integrated view of the coupled nature of biogeochemical cycles in wetland systems. The influence of the elemental cycles is discussed at a range of scales in the context of environmental change including climate, sea level rise, and water quality. Frequent examples of key methods and major case studies are also included to help the reader extend the basic theories for application in their own system. Some of the major topics discussed are: Flooded soil and sediment characteristics Aerobic-anaerobic interfaces Redox chemistry in flooded soil and sediment systems Anaerobic microbial metabolism Plant adaptations to reducing conditions Regulators of organic matter decomposition and accretion Major nutrient sources and sinks Greenhouse gas production and emission Elemental flux processes Remediation of contaminated soils and sediments Coupled C-N-P-S processes Consequences of environmental change in wetlands# The book provides the foundation for a basic understanding of key biogeochemical processes and its applications to solve real world problems. It is detailed, but also assists the reader with box inserts, artfully designed diagrams, and summary tables all supported by numerous current references. This book is an excellent resource for senior undergraduates and graduate students studying ecosystem biogeochemistry with a focus in wetlands and aquatic systems.

Download or read book Seasonal Variability in Total Mercury and Methylmercury at Elephant Butte and Caballo Reservoirs Sierra County New Mexico written by Christopher M. Canavan and published by . This book was released on 1998 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Water Quality Assessments written by Deborah V Chapman and published by CRC Press. This book was released on 1996-08-22 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt: This guidebook, now thoroughly updated and revised in its second edition, gives comprehensive advice on the designing and setting up of monitoring programmes for the purpose of providing valid data for water quality assessments in all types of freshwater bodies. It is clearly and concisely written in order to provide the essential information for all agencies and individuals responsible for the water quality.

Download or read book Methylmercury and Neurotoxicity written by Sandra Ceccatelli and published by Springer. This book was released on 2014-04-13 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury (Hg) is a global pollutant that knows no environmental boundaries. Even the most stringent control of anthropogenic Hg sources will not eliminate exposure given its ubiquitous presence. Exposure to Hg occurs primarily via the food chain due to MeHg’s accumulation in fish. Latest US statistics indicate that 46 States have fish consumption advisories. In addition, Hg is a common pollutant in hazardous waste sites, with an estimated 3-4 million children living within one mile of at least one of the 1,300+ active hazardous waste sites in the US. The effects on intellectual function in children prenatally exposed to MeHg via maternal fish consumption have been the subject of two on-going major, prospective, longitudinal studies in the Seychelles and the Faroe Islands. It is important to recognize that the risk for MeHg exposure is not limited only to islanders with high fish consumption. This book will provide state-of-the-art information to the graduate student training in toxicology, risk assessors, researchers and medical providers at large. It is aimed to bring the reader up to date on contemporary issues associated with exposure to methylmercury, from its effects on stem cells and neurons to population studies.