Abstract
This book, the first of its kind, extrapolates state of the art science, albeit a dynamic process into a format that can be followed from mercury in the environment to the analytical developments of mercury in the laboratory back to speciation, transformation, fate, and transportation in the environment.
The text is edited by 3 authors, Guangliang Liu, Yong Cai, and Nelson O’Driscoll. The first 2 are from the Department of Chemistry Biochemistry and Southeast Environmental Research Center at Florida International University in Miami, Florida, and the last author is from the Department of Earth and Environmental Sciences at Acadia University in Nova Scotia, Canada. Their list of contributing scientists is extensive and multinational. This provides a unique perspective on this topic as mercury epidemics have occurred in Asia, and the Asian countries account for approximately 65% of total global emissions of mercury.
The introductory chapter which provides an overview of mercury in the environment states the relevance of this topic to the reader by laying the groundwork for the ubiquity of mercury in the environment. Both naturally occurring and anthropogenic sources can release mercury into the environment with an annual global input into the atmosphere estimated to be around 5000 to 6000 tons of mercury. Aside from the natural sources including volcanic activity and geothermal emissions, the anthropogenic sources are significant. Of the 3 man-made point sources, combustion generally contributes more than 80% of the anthropogenic mercury source emissions with fossil fuel combustion for power generation, and industrial and residential heating contributes about 45% of the total global emissions.
This text is divided into 4 parts following the overview of mercury in the environment. Part I provides a description of the analytical developments with respect to mercury and consists of 2 chapters. These 2 chapters include advances in speciation analysis of mercury and measuring gas phase mercury emissions from industrial effluents. The former chapter includes the applications of various laboratory techniques including gas chromatography, high-performance liquid chromatography, capillary electrophoresis, x-ray absorption spectroscopy, and stable isotope dilution. This section concludes with a future outlook that explains why this is so important. With the forecasting of a 2 billion dollar a year market for equipment and consumables to measure and remove mercury from stack gases in various industries, the need is great due to a combination of stringent regulations and industrial growth of mercury continuous emission monitor developments capable of integrating with the mercury removal systems to ensure environmental sustainability of mercury emitting industries worldwide. Both chapters are extensive, include detailed tables and figures given the several species of mercury present in the environment, and are fully referenced.
Part I sets the stage for part II of the book: Speciation and Transformation. This section consists of 6 chapters, which includes a chapter on each of the following: atmospheric chemistry, microbial transformation, photoreactions in aquatic systems, chemical speciation in soil and sediment, dissolved organic matter and biogeochemistry, and concludes with a chapter on tracking geochemical transformations and transport of mercury through isotope fractionation. These chapters are extremely detailed, provide appropriate figures where necessary, and provide the reader with a current understanding of the state of the art technology with respect to mercury speciation and transportation. Each chapter is extensively referenced with current publications in both peer-reviewed journals and books. These sections are especially useful for the research scientist and are too technical for the lay reader interested in just the toxicology of mercury.
Part III of this text discusses the transport and fate of mercury in 4 chapters including atmospheric transport, adsorption on solids in the aquatic ecosystem, exchange of elemental mercury between oceans and the atmosphere, and concludes with the exchange of mercury between the atmosphere and the terrestrial ecosystem. These chapters are also extremely detailed, provide appropriate figures where necessary and provide the reader with a current understanding of the state of the art technology with respect to mercury transport and fate. Each chapter is extensively referenced with current publications in both peer-reviewed journals and books. These sections are again especially useful for the research scientist and are too technical for the lay reader interested in mercury as they contain mathematical formulae. Useful sections in the chapters include knowledge gaps, key uncertainties, data requirements, and limitations specific to each chapter topic. Of particular interest to readers is that the terrestrial ecosystems are as a whole a sink for atmospheric mercury and are dependent on the future environmental and soil conditions and potential disturbances of these reservoirs over time.
The last section, part IV describes the bioaccumulation, toxicity, and metallomics of mercury. There are 4 chapters in this section and 1 chapter is devoted to bioaccumulation, 1 to mercury toxicity with respect to methyl mercury, 1 chapter to metallomics, and the last chapter to the human health significance of dietary exposure to methyl mercury.
Given that there is only 1 chapter that deals directly with toxicology, its presence in the title implies that more of the book should be concerned with toxicology. Consistent with the previous chapters, this chapter is extremely well referenced with current peer-reviewed published scientific literature. The toxicology chapter does discuss the first reported epidemic of mercury referred to as Minamata disease in satisfactory detail. The chapter is strong on methyl mercury but weak on the toxicity of the other species of mercury including elemental and inorganic mercury, especially with respect to target organ toxicity. It is not detailed enough for the physician or clinical practitioner with respect to target organ toxicity or treatment of mercury toxicity.
The presence of the metallomics chapter in this section of the text solidifies how state of the art this book is. Metallomics was a word coined in 2004 to highlight the growing recognition of the role of metal ions in genes and proteins. Similar to genomics and proteomics, metallomics can be thought of as the entirety of metal species present in biological systems and refers to the study of their interaction and functional connection with genes, proteins, metabolites, and other biological molecules in a biological system. This chapter is interesting but should have included a section on future research directions as other chapters have given that this is an emerging research topic and of interest to the new breed of toxicologists trained in the “omics.”
The last chapter on the human health significance of dietary exposure to methyl mercury is of particular interest to the public health professional and incorporates many scientific disciplines including public health, toxicology, dietetics and nutrition, mental health, epidemiology, and environmental science. The chapter points to the widespread contamination of mercury in the environment with particular interest to methyl mercury and its bioaccumulation up through the food chain. The reader is informed about the research studies including the prospective cohort studies examining methyl mercury exposed children in New Zealand, the Faroe Islands, and the Seychelle Islands. This chapter discusses the neurodevelopmental outcomes as well as the sensitivity of the neuropsychological tests necessary to depict subtle changes as well as cardiovascular outcomes of exposed populations.
This whole section is the least technical in the entire book and is easily of interest to the lay reader or nontechnical person. It does not seem to follow with all the preceding chapters which are extremely technical in nature, but notwithstanding, the book comes together as a whole and the reader may pull from the text their particular interests. This text is useful for researchers, graduate students, chemists, public health professionals, and environmental regulatory professionals. Given the dynamic nature of this topic of mercury species, transformation, fate, and transport within the environment and the recent strides made over the last 6 to 7 years, there are few places where researchers can broaden their knowledge base from a single source.
Overall, the chemistry section of the book is highly technical, sophisticated, and comprises approximately three quarters of the book and the remaining quarter covers toxicology, metallomics, and public health which are less technical. However, the book is extremely well written and is a compelling read. The book accomplishes its goal to provide a state of the art review with respect to mercury. Given the multinationality of all the contributing authors, the book flows flawlessly and each contributing author followed the general guidelines as set by the editors. The contributing authors are well-known experts in their fields and are comprised mostly of academicians with university appointments. The book would not be useful as a text for a course since it is only concerned with 1 metal, mercury. However, it is very useful as a resource for graduate students and professors, and researchers whose area of interest lies in the areas of mercury with respect to its speciation, transformation, environmental transport, fate, bioaccumulation, and toxicity including metallomics. The book serves as an excellent educational resource.
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