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Water Contaminants

KENNETH P. CANTOR, MARY H. WARD, LEE E. MOORE, and JAY H LUBIN

in Cancer Epidemiology and Prevention

This chapter discusses water contaminants that may contribute to the human cancer burden. Specifically, it addresses the epidemiologic evidence for several contaminants and includes information on ... More

This chapter discusses water contaminants that may contribute to the human cancer burden. Specifically, it addresses the epidemiologic evidence for several contaminants and includes information on their levels and environmental distribution, as well as individual susceptibility, where data exist. The three categories of drinking water contaminants that may be carcinogenic and that have been studied most systematically are arsenic, disinfection by-products, and nitrate. In addition, radionuclides, microbiological agents, organic compounds from human commerce, and asbestiform particles have been reported to cause cancer, either as they occur in drinking water or in other media, giving rise to suspicion about their carcinogenicity when ingested. Future research priorities and prevention strategies are discussed.Less

Ether/Or

in Image and Reality: Kekule, Kopp, and the Scientific Imagination

A paper by Alexander Williamson, read at the annual meeting of the British Association for the Advancement of Science in Edinburgh on August 3, 1850, was groundbreaking in a lot of ways. As the first ... More

A paper by Alexander Williamson, read at the annual meeting of the British Association for the Advancement of Science in Edinburgh on August 3, 1850, was groundbreaking in a lot of ways. As the first of an important series of papers on the formation of ethers, the constitutions of molecules, and reaction dynamics, Williamson's work would radically alter chemical theory. Whether consciously or only instinctively, Williamson understood the importance of using vivid mental images to comprehend and explore molecular reality in scientific fashion. His intellectual formation was influenced in part by the British chemist Thomas Graham, who in 1833 announced his discovery of the law of gaseous diffusion. Williamson discovered that he could form ether by reacting “ethylate of potash” (potassium ethoxide) with ethyl iodide. After his experiments on etherification, he published three papers charting the early stages of an investigative route toward the systematic conceptual dissection of organic compounds, offering the promise of a secure pathway into organic chemistry.Less

Introduction

Phoebe N. Okowa

in State Responsibility for Transboundary Air Pollution in International Law

This introductory chapter first sets out the purpose of the book, which is to examine what states claim in the context of disputes involving transboundary air pollution and what they protest to as ... More

This introductory chapter first sets out the purpose of the book, which is to examine what states claim in the context of disputes involving transboundary air pollution and what they protest to as part of the evaluation of the content of the applicable legal regime. The study focuses on three principal sources of pollutants, namely pollution from industrial activities (in particular acid deposition from sulphur and nitrogen emissions, as well as volatile organic compounds), atmospheric nuclear tests, and accidental radioactive contamination from the civil uses of nuclear energy. An overview of the subsequent chapters is also presented.Less

Combustion Calorimetry

José A. Martinho Simões and Manuel Minas da Piedade

in Molecular Energetics: Consensed-Phase Thermochemical Techniques

Calorimetric studies of combustion reactions in oxygen and fluorine atmospheres have been a major source of enthalpy of formation data, particularly for organic and inorganic compounds. As referred ... More

Calorimetric studies of combustion reactions in oxygen and fluorine atmospheres have been a major source of enthalpy of formation data, particularly for organic and inorganic compounds. As referred to in the previous chapter, in bomb combustion calorimetry the reaction proceeds inside a pressure vessel—the bomb—at constant volume, and in this case the derived quantity is ΔcUo. In flame calorimetry the reaction occurs in a combustion chamber, which is in communication with the atmosphere, and the measurements lead to ΔcHo. The methods of combustion calorimetry will be described in the following paragraphs. “Conventional” combustion calorimeters operate on a “macro” scale, that is, they require samples of 0.5–1.0 g per experiment. Unfortunately, many interesting compounds are available only in much smaller amounts. In the case of oxygen combustion calorimetry, however, several combustion microcaloriemeters that only demand 2–50 mg samples have been developed in recent years. The achievements and trends in this area through 1999 have been reviewed, and interested readers are directed to these publications. Since then, a few new apparatus have been reported. Nevertheless, it should be pointed out that the general principles and techniques used to study compounds at the micro scale are not greatly different from those used in macro combustion calorimetry. Static-bomb combustion calorimetry is particularly suited to obtaining enthalpies of combustion and formation of solid and liquid compounds containing only the elements C, H, O, and N. The origins of the method can be traced back to the work of Berthelot in the late nineteenth century. Most static-bomb calorimeters used are of the isoperibol type, such as the one in figure 7.1. Here, the bomb A is a pressure vessel of ∽300 cm3 internal volume. Combustion bombs are usually made of stainless steel and frequently have an internal platinum lining to prevent corrosion. In a typical high-precision experiment, the platinum ignition wire B connects the two electrodes C, which are affixed to the bomb head. A cotton thread fuse D (other materials such as polyethene are also used), of known energy of combustion, is weighed to a precision of±10−5−10−6 g and tied to the platinum wire. Less

Fluorous Phases and Compressed Carbon Dioxide as Alternative Solvents for Chemical Synthesis: A Comparison

Walter Leitner

in Green Chemistry Using Liquid and Supercritical Carbon Dioxide

The principal goal of basic research in chemical synthesis is the development of efficient tools for functional group transformations and for the assembly of building blocks during the construction ... More

The principal goal of basic research in chemical synthesis is the development of efficient tools for functional group transformations and for the assembly of building blocks during the construction of molecules with increasing complexity. Traditionally, new approaches in this area have focused on the quest for new reaction pathways, reagents, or catalysts. Comparably less effort has been devoted to utilize the reaction medium as a strategic parameter, although the use of solvents is often crucial in synthetically useful transformations. The first choice for a solvent during the development of a synthetic procedure is usually an organic liquid, which is selected on the basis of its protic or aprotic nature, its polarity, and the temperature range in which the reaction is expected to proceed. Once the desired transformation is achieved, yield and selectivity are further optimized in the given medium by variation of temperature, concentration, and related process parameters. At the end of the reaction, the solvent must be removed quantitatively from the product using conventional workup techniques like aqueous extraction, distillation, or chromatography. If the synthetic procedure becomes part of a large-scale application, the solvent can sometimes be recycled, but at least parts of it will ultimately end up in the waste stream of the process. Increasing efforts to develop chemical processes with minimized ecological impact and to reduce the emission of potentially hazardous or toxic organic chemicals have stimulated a rapidly growing interest to provide alternatives to this classical approach of synthesis in solution. At the same time, researchers have started to realize that the design and utilization of multifunctional reaction media can add a new dimension to the development of synthetic chemistry. In particular, efficient protocols for phase separations and recovery of reagents and catalysts are urgently required to provide innovative flow schemes for environmentally benign processes or for high-throughput screening procedures. Fluorous liquid phases and supercritical carbon dioxide (sc CO2) have received particular attention among the various reaction media that are discussed as alternatives to classical organic solvents. The aim of this chapter is to compare these two media directly and to critically evaluate their potential for synthetic organic chemistry. Less

Outdoor Air Pollution

Andrea Hricko

in Safe and Healthy School Environments

This chapter discusses outdoor air pollution in school environments. Outdoor (ambient) air pollution presents a number of issues in the school environment, including exposure of children to diesel ... More

This chapter discusses outdoor air pollution in school environments. Outdoor (ambient) air pollution presents a number of issues in the school environment, including exposure of children to diesel exhaust from older buses, potential risks for students who play or exercise outdoors on smoggy days, and exposure to emissions from nearby traffic and industrial facilities. There are steps that school administrators can take to protect children and address pollution. These include limiting outdoor activities on high ozone days, keeping students indoors for recess and practices, and contacting the air pollution control authority with any concerns about sources of pollution very close to the school, and discuss the record of the polluting facility.Less

Costs of Air Quality Regulation

Randy A. Becker and J. Vernon Henderson

in Behavioral and Distributional Effects of Environmental Policy

An ongoing debate in the United States concerns the costs imposed by environmental regulations on industry. This chapter explores some of the costs associated with air quality regulation, focusing on ... More

An ongoing debate in the United States concerns the costs imposed by environmental regulations on industry. This chapter explores some of the costs associated with air quality regulation, focusing on regulation pertaining to ground-level ozone and its effects on two industries sensitive to such regulation: industrial organic chemicals and miscellaneous plastic products. Both of these industries are major emitters of volatile organic compounds and nitrogen oxides, the chemical precursors to ozone. Using plant-level data from the U.S. Census Bureau's Longitudinal Research Database (LRD), the chapter analyzes the effects this type of regulation has had on the timing and magnitudes of investments by firms in these industries and on their operating costs. As an alternative way to assess costs, it also employs plant-level data from the U.S. Census Bureau's Pollution Abatement Costs and Expenditures survey.Less

Satellites and Pluto

Yuk L. Yung and William B. DeMore

in Photochemistry of Planetary Atmospheres

The presence of an atmosphere on a small planetary body the size of the Moon is surprising. Loss of material by escape would have depleted the atmosphere over the age of the solar system. Since ... More

The presence of an atmosphere on a small planetary body the size of the Moon is surprising. Loss of material by escape would have depleted the atmosphere over the age of the solar system. Since these objects are not large enough to possess, or to sustain for long, a molten core, continued outgassing from the interior is not expected. However, it is now known that four small bodies in the outer solar system possess substantial atmospheres: lo, Titan, Triton, and Pluto. These atmospheres range from the very tenuous on lo (of the order of a nanobar) to the very massive on Titan (of the order of a bar). The atmospheric pressures on Triton and Pluto are of the order of 10 μbar. Perhaps the most interesting questions about these atmospheres concern their unusual origin and their chemical evolution. lo is the innermost of the four Galilean satellites of Jupiter, the other three being Ganymede, Europa, and Callisto. All the Galilean moons are comparable in size, but there is no appreciable atmosphere on the other moons. The first indications that lo possesses an atmosphere came in 1974 with the discovery of sodium atoms surrounding the satellite and the detection of a well-developed ionosphere from the Pioneer 10 radio occultation experiment. The Voyager encounter in 1979 established the existence of active volcanoes as well as SOa gas. These are the only extraterrestrial active volcanoes discovered to date, and they owe their existence to a curious tidal heating mechanism associated with the 2:1 resonance between the orbits of lo and Europa. Less

Phytoplankton Productivity

John Raven

in Marine Plankton: A practical guide to ecology, methodology, and taxonomy

This chapter describes the productivity of phytoplankton, from the initial energy and chemical requirements for photosynthesis to the rate of production of heterotrophic organisms. Phytoplankton are ... More

This chapter describes the productivity of phytoplankton, from the initial energy and chemical requirements for photosynthesis to the rate of production of heterotrophic organisms. Phytoplankton are the planktonic organisms which account for most of the primary production in the ocean. Their characteristic trophic mode is the production of organic compounds using energy from light and chemical elements from inorganic compounds, known as phototrophy, or more strictly photolithotrophy. This process uses water as the electron donor and the reduction of inorganic carbon producing sugars, from which all other cell components are made using inorganic forms of nitrogen, phosphorus, and all the other chemical elements needed to produce cells.Less

Emissions and Urban Air

William G. Wilson

in Constructed Climates: A Primer on Urban Environments

This chapter looks at the issues involving air, covering the causes and consequences of contributions from both human and nonhuman organisms. Humans dominate emissions in urban areas. Air quality ... More

This chapter looks at the issues involving air, covering the causes and consequences of contributions from both human and nonhuman organisms. Humans dominate emissions in urban areas. Air quality studies categorize emission sources as either point or nonpoint, roughly corresponding to fixed or moving, respectively. Both types of emissions roughly match maps of population density, at least in the United States. Vegetation and soils also emit chemicals, often as a by-product of evolution in the face of herbivory, competition, and environmental stresses that yielded chemical responses and defenses. These emissions can reduce air quality in urban areas, with some tree species being worse “violators” than others. These emissions feed into, among other pollutants, ozone formation in the hot summer months. For a more complete understanding of urban pollution, the chapter provides an overview of the chemical reactions that link volatile organic compounds (VOCs), reactive nitrogen, sunshine, ozone, and eye-stinging pollutants.Less

Top-down pressures and indirect defences

Edward E. Farmer

in Leaf Defence

Plant populations are remodelled after carnivore removal, and the animals that eat herbivores can play critical roles in the biology of the leaf. Of particular interest is the fact that plants often ... More

Plant populations are remodelled after carnivore removal, and the animals that eat herbivores can play critical roles in the biology of the leaf. Of particular interest is the fact that plants often facilitate the task of the carnivore in its quest to find food, either by providing information to predators or by housing them. The chapter examines several interactions between bottom-up and top-down defence and uses an example to illustrate a mechanism that helps to maintain chemical polymorphism. Ant–plant interactions, extrafloral nectaries and food bodies are discussed with reference to ant vachellias from the neotropics. Examples of mite domatia are also given. The chapter then moves on to an examination of predator and parasitoid attraction by volatile organic compounds released by plants and uses examples from maize and other plants to illustrate the important role of oral secretions in the elicitation of volatile production. The use of plant volatiles to attract predators may be more far-ranging than is often thought. Finally, to demonstrate that some of the literature on plant volatiles needs to be read with caution, a potentially misleading report on acacias that were damaged by kudus is examined.Less

Coatings from Liquid and Supercritical Carbon Dioxide

Yury Chernyak, Florence Henon, Erik Hoggan, Brian Novick, Joseph M. Desimone, and Carbonell Ruben

in Green Chemistry Using Liquid and Supercritical Carbon Dioxide

This chapter describes several aspects of the use of carbon dioxide as a solvent or cosolvent in coating applications. The primary impetus for using carbon dioxide for this purpose has been the ... More

This chapter describes several aspects of the use of carbon dioxide as a solvent or cosolvent in coating applications. The primary impetus for using carbon dioxide for this purpose has been the alleviation of volatile emissions and liquid solvent wastes. However, the special physical properties of liquid and supercritical carbon dioxide may offer some processing advantages over conventional organic or aqueous solvents. Liquid carbon dioxide is quite compressible, and a reduction in temperature results not only in a reduction in the operating pressure, but also in a significant increase in the liquid density to values of approximately 0.9 g/cm3. At these high liquid densities, carbon dioxide exhibits improved solvent performance, but with much lower viscosities and interfacial tensions than aqueous or organic liquid solvents. Under supercritical conditions, carbon dioxide also exhibits high densities, low viscosities, and improved solvent power. Low viscosities and interfacial tensions tend to facilitate the transport of the solvents into any crevices or imperfections on the surface to be covered, and this might prove advantageous in the coating of patterned or etched surfaces. Since carbon dioxide dissolves and diffuses easily into many different polymers and organic liquids, it can also be used to reduce the viscosity of coating solutions. Whether in the liquid or the supercritical state, the temperature and pressure of the mixture can be used to control its physical properties in ways that are impossible to achieve with traditional solvents. These distinguishing features have raised the level of industrial interest in carbon dioxide as a solvent for coating applications, beyond those based solely on environmental concerns. In this chapter, we will discuss current applications and research on the use of CO2 as a solvent for coatings. The first section deals with spray coating from supercritical CO2. Subsequent sections deal with the use of liquid coatings, such as spin and free meniscus coatings, and impregnation coatings. Since the start of the 20th century (ca. 1907), atomization has been the basis for conventional spray coating applications (Muirhead, 1974). Typically, atomization is caused by high shear of the coating fluid in air, leading to droplet or particle formation. Less

Carbon Dioxide as a Reactant and Solvent in Catalysis

Takao Ikariya and Ryoji Noyori

in Green Chemistry Using Liquid and Supercritical Carbon Dioxide

An increased awareness of global atmospheric carbon levels and heightened efforts to recover industrial emissions prior to their release into the environment has led to the availability of an ... More

An increased awareness of global atmospheric carbon levels and heightened efforts to recover industrial emissions prior to their release into the environment has led to the availability of an unprecedented amount of carbon dioxide for industrial utilization. Unfortunately, chemical utilization of carbon dioxide as an industrial feedstock is limited by thermodynamic and kinetic constraints. Toxic carbon monoxide, the main competitor in many processes, is used in industry instead because CO2 is perceived to be less reactive and its efficient catalytic conversion has remained elusive. The major commercial uses of CO2 today are in beverages, fire extinguishers, and refrigerants, where inert physical properties such as oxidative and thermodynamic stability are advantageous. It is this stability that has limited the use of CO2 to only a very few synthetic chemical processes (urea, aspirin, carbonates) despite the enormous availability of this resource. The conversion of CO2 into useful organic compounds will likely rely on the use of metal catalysts to lower energy inputs. Increasingly, the use of supercritical carbon dioxide appears to offer significant advantages in the catalytic activation of CO2 to yield useful products. Liquid or supercritical CO2 (sc CO2) can be used as a reaction medium and can potentially replace conventional organic solvents to serve as an environmentally benign reaction medium (Ikariya and Noyori, 1999; Jessop and Leitner, 1999; Jessop et al., 1995b; Noyori, 1999). A supercritical fluid (SCF) is any substance that has a temperature and pressure higher than their critical values and which has a density close to or higher than its critical density (Jessop and Leitner, 1999; Jessop et al., 1995b). Carbon dioxide has a critical temperature of 31.0 °C and a critical pressure of 71.8 bar. The supercritical region of the phase diagram is the one at temperatures higher than the Tc and pressures higher than the Pc at which the liquid and gas phases become indistinguishable. Below Tc, liquid CO2 can be maintained under relatively modest pressures. Subcritical liquid CO2 behaves like any other nonpolar liquid solvent. Properties such as density are continuous above the Tc and discontinuous below it. Less

Air Pollution, Air Quality, and Climate Change

Alan H. Lockwood

in Heat Advisory: Protecting Health on a Warming Planet

The effects of climate change on air quality are difficult to model due to the large number of unpredictable variables. Hotter temperatures favor ozone production. Higher atmospheric water content ... More

The effects of climate change on air quality are difficult to model due to the large number of unpredictable variables. Hotter temperatures favor ozone production. Higher atmospheric water content may blunt this effect in some regions. Higher levels of natural volatile organic compounds (VOCs), such as terpenes from plants, are likely to act synergistically with anthropogenic VOCs to favor ozone production. Droughts increase wildfire risks that produce particulate pollution and carbon monoxide, a VOC involved in ozone production. Some models predict increased ozone concentrations in many urban settings. Future revisions of National Ambient Air Quality Standards, a process driven by politics and science, should consider these effects.Less

The Atmospheric Component of Biogeochemical Cycles in the Amazon Basin

Paulo Artaxo

in The Biogeochemistry of the Amazon Basin

Tropical forests, with their high biological activity, have the potential to emit large amounts of trace gases and aerosol particles to the atmosphere. The accelerated development and land clearing ... More

Tropical forests, with their high biological activity, have the potential to emit large amounts of trace gases and aerosol particles to the atmosphere. The accelerated development and land clearing that is occurring in large areas of the Amazon basin suggest that anthropogenic effects on natural biogeochemical cycles are already occurring (Gash et al. 1996). The atmosphere plays a key role in this process. The tropics are the part of the globe with the most rapidly growing population, the most dramatic industrial expansion and the most rapid and pervasive change in land use and land cover. Also the tropics contain the largest standing stocks of terrestrial vegetation and have the highest rates of photosynthesis and respiration. It is likely that changes in tropical land use will have a profound impact on the global atmosphere (Andreae 1998, Andreae and Crutzen 1997). A significant fraction of nutrients are transported or dislocated through the atmosphere in the form of trace gases, aerosol particles, and rainwater (Keller et al. 1991). Also the global effects of carbon dioxide, methane, nitrous oxide, and other trace gases have in the forest ecosystems a key partner. The large emissions of isoprene, terpenes, and many other volatile organic compounds could impact carbon cycling and the production of secondary aerosol particles over the Amazon region. Vegetation is a natural source of many types of aerosol particles that play an important role in the radiation budget over large areas (Artaxo et al. 1998). There are 5 major reservoirs in the Earth system: atmosphere, biosphere (vegetation, animals), soils, hydrosphere (oceans, lakes, rivers, groundwater), and the lithosphere (Earth crust). Elemental cycles of carbon, oxygen, nitrogen, sulfur, phosphorus, and other elements interact with the different reservoirs of the Earth system. The carbon cycle has important aspects in tropical forests due to the large amount of carbon stored in the tropical forests and the high rate of tropical deforestation (Jacob 1999). In Amazonia there are two very different atmospheric conditions: the wet season (mostly from November to June) and the dry season (July-October) (see Marengo and Nobre, this volume). Biomass burning emissions dominate completely the atmospheric concentrations over large areas of the Amazon basin during the dry season (Artaxo et al. 1988). Less

Free-Radical Chemistry in Supercritical Carbon Dioxide

J. M. Tanko

in Green Chemistry Using Liquid and Supercritical Carbon Dioxide

During the 1990s, the chemical industry has focused on ways to reduce and prevent pollution caused by chemical synthesis and manufacturing. The goal of this approach is to modify existing reaction ... More

During the 1990s, the chemical industry has focused on ways to reduce and prevent pollution caused by chemical synthesis and manufacturing. The goal of this approach is to modify existing reaction conditions and/or to develop new chemistries that do not require the use of toxic reagents or solvents, or that do not produce toxic by-products. The terms “environmentally benign synthesis and processing” and “green chemistry” have been coined to describe this approach where the environmental impact of a process is as important an issue as reaction yield, efficiency, or cost. Most chemical reactions require the use of a solvent that may serve several functions in a reaction: for example, ensuring homogeneity of the reactants, facilitating heat transfer, extraction of a product (or by-product), or product purification via chromatography. However, because the solvent is only indirectly involved in a reaction (i.e., it is not consumed), its disposal becomes an important issue. Thus, one obvious approach to “green chemistry” is to identify alternative solvents that are nontoxic and/or environmentally benign. Supercritical carbon dioxide (sc CO2) has been identified as a solvent that may be a viable alternative to solvents such as CCl4, benzene, and chloroflurocarbons (CFCs), which are either toxic or damaging to the environment. The critical state is achieved when a substance is taken above its critical temperature and pressure (Tc, Pc). Above this point on a phase diagram, the gas and liquid phases become indistinguishable. The physical properties of the supercritical state (e.g., density, viscosity, solubility parameter, etc.) are intermediate between those of a gas and a liquid, and vary considerably as a function of temperature and pressure. The interest in sc CO2 specifically is related to the fact that CO2 is nontoxic and naturally occurring. The critical parameters of CO2 are moderate (Tc = 31 °C, Pc = 74 bar), which means that the supercritical state can be achieved without a disproportionate expenditure of energy. For these two reasons, there is a great deal of interest in sc CO2 as a solvent for chemical reactions. This chapter reviews the literature pertaining to free-radical reactions in sc CO2 solvent. Less

Electronic Explanations of the Periodic System Developed by Chemists

Eric Scerri

in The Periodic Table: Its Story and Its Significance

Given the advances in explanations of the periodic system provided by physicists in the first quarter of the twentieth century, described in chapter 7, it is interesting to consider what advances, ... More

Given the advances in explanations of the periodic system provided by physicists in the first quarter of the twentieth century, described in chapter 7, it is interesting to consider what advances, if any, chemists achieved during the same period. Unlike physicists, chemists were working largely inductively with experimental data on the elements and not via any theoretical arguments. However, in many instances, the electronic configurations proposed by chemists were superior to those postulated by such physicists as Niels Bohr and Edmund Stoner. This is not entirely surprising given the chemist’s familiarity with the properties of the elements. Inductive arguments based on the macroscopic behavior of elements were often more fruitful than the deductive arguments based on physical principles. Moreover, as described in chapter 7, even physicists’ routes to electronic configurations were not always as deductive as their authors claimed them to be. The starting point for the chemical contributions to the assignment of electronic configurations can be regarded as J.J. Thomson’s discovery of the electron in 1897, since without the existence of this particle there could be no electronic configurations. In 1902, the American chemist Gilbert Norton Lewis began speculating about the electronic structure of atoms, although he did not publish his views due to the prevailing empiricist climate in US chemistry, which was rather hostile toward theoretical approaches. Considerably later, Lewis recalled his early thoughts on the constitution of atoms: . . . In the year 1902 (while I was attempting to explain to an elementary class in chemistry some of the ideas involved in the periodic law) becoming interested in the new theory of the electron, and combining this idea with those implied in the periodic classification, I formed an idea of the inner structure of the atom which, although it contained certain crudities, I have ever since regarded as representing essentially the arrangement of electrons in the atom. . . . Some dated fragments of this work still survive, including a diagram in which Lewis depicts the electronic structures of the elements from helium up to fluorine. Less

One of the Best Enterprises in Russia

Peter Thomson

in Sacred Sea: A Journey to Lake Baikal

The Angara River races out of Lake Baikal like a daughter fleeing her angry father for the arms of her lover. So goes the legend of the powerful river that is Baikal’s only outlet. Until the 1950s, ... More

The Angara River races out of Lake Baikal like a daughter fleeing her angry father for the arms of her lover. So goes the legend of the powerful river that is Baikal’s only outlet. Until the 1950s, you could see a huge rock near the mouth of the river that was said to prove the legend—the rock hurled by father Baikal toward his recalcitrant offspring, hoping to block her way as she ran off to join her beloved Yenisei, the great river to the west. Today, only a tiny tip of what’s known as Shaman Rock is still visible. Powerful Baikal could not block his daughter’s way and tame her energies, but humans could. They captured daughter Angara behind a series of hydroelectric dams and put her to work for the good of the Soviet people. One of the dams raised the level of Baikal by a meter and submerged most of the great rock in the river. Isolated in the middle of sparsely populated Siberia, its colossal depths and unique ecosystem enclosed behind its barrier of mountains, it would be easy to imagine that Baikal remains a world unto itself. But today that would be just an act of imagination. The lake may have stood apart for millions of years, but in the last 100 years, humans have speeded up time and collapsed space, and Baikal can no longer blithely follow its own, idiosyncratic course. Some changes were already evident early in the twentieth century. The Barguzin sable, source of so much wealth over more than 200 years, was on the verge of extinction, its long decline punctuated by Nicholas II’s belated decision to protect it with the Barguzinsky Nature Reserve. The limits of the limitless lake itself were starting to be tested, too—Baikal’s populations of omul and sturgeon were crashing as human populations rose, spawning habitat was disrupted, and new fishing technology was introduced. And along its southern shores, workers were clearing, blasting, flattening, and filling in, laying the path for the needle that would truly puncture Baikal’s bubble of isolation, 250 years after the arrival of the first Russians. Less