Bivalves belong to the invertebrate phylum Mollusca, which also includes snails, squids, and octopuses. Some well-known bivalves include clams, scallops, mussels, and oysters.

Bottled Water

Sales of bottled water in the United States have increased dramatically since the 1980s. This increase is largely due to an effective advertising campaign that directly appeals to fitness-conscious Americans looking for healthy alternatives to tap water.

Bretz, J Harlen

J Harlen Bretz is best known for his hypothesis that floods of enormous volumes once swept across southeastern Washington and on out the Columbia River Gorge to the Pacific Ocean. Bretz was widely criticized by his contemporaries for his "outrageous hypothesis" while continuing to use his own observations, not popular opinion, to develop his ideas.

Bridges, Causeways, and Underwater Tunnels

Bridges, causeways, and underwater tunnels are all passageways that allow travel above, across, and beneath bodies of water such as rivers, bayous, and bays. On the other hand, these artificial structures can create barriers or obstacles to wildlife that live underneath and above these waters.

Brines, Natural

Natural brines are waters with very high to extremely high concentrations of dissolved constituents—elements, ions, and molecules. Brines are commonly considered to be those waters more saline, or more concentrated in dissolved materials, than sea water (35 grams of dissolved constituents per kilogram of sea water).

Bureau of Reclamation, U.S

The U.S. Bureau of Reclamation, an agency of the Department of the Interior, is one of the principal water management agencies of the federal government.

California, Water Management in

California and water: the two always have been, and always will be, inextricably linked. No resource is as vital to California's cities, agriculture, industry, recreation, scenic beauty, and environmental preservation as its "liquid gold." And no resource is as steeped in controversy.


Human societies have long worked on changing nature's waterways for their purposes. Canals are artificial waterways constructed for irrigation, drainage, river overflows, water supplies, communications, and navigation, or in connection with power generation from hydroelectric dams.

Carbon Dioxide in the Ocean and Atmosphere

Carbon dioxide (CO2) is considered a trace gas in the atmosphere because it is much less abundant than oxygen or nitrogen. However, this trace gas plays a vital role in sustaining life on Earth and in controlling the Earth's climate by trapping heat in the atmosphere.

Careers in Environmental Education

Educating others in environmental principles and theories is a rewarding activity, and one that some individuals pursue as a full-time profession. Environmental education has evolved over the last century from a oncesmall field of environmental interpretation to a growing discipline with new opportunities steadily arising.

Careers in Environmental Science and Engineering

Environmental science as it relates to water may be broadly defined as the study of how fresh-water and marine-water environments are faring in the face of a swelling human population, degradation by pollution and the disturbance of natural habitats, problems with either excess or insufficient water, and threats to the sustainability of living and nonliving resources. Environmental science is interdisciplinary, including aspects of ecology, environmental management, biology, chemistry, microbiology, zoology, geology, soil science, statistics, and land-use planning.

Careers in Fresh-Water Chemistry

As water reacts with rocks, minerals, or biological materials, or is impacted by pollution or a land-use practice, the chemical composition of the water may be changed in a predictable way. Chemical analysis of water allows both natural processes and human-influenced changes to be characterized, and may enable the chemist to determine the "history" of a water parcel.

Careers in Fresh-Water Ecology

Fresh-water ecology seeks to understand the relationship between organisms and their environment, and how changes in one part of the system will affect other parts of the system. Many kinds of scientific and communication skills are necessary to understand successfully the ecology of freshwater ecosystems; therefore, career opportunities are numerous.

Careers in Geospatial Technologies

A host of technical specialists—geographers, geologists, hydrologists, oceanographers, and others—studies the water components of Earth's surface from various points of view. Some of these professionals hold B.S.

Careers in Hydrology

Hydrology is the science of the movement of water through the atmosphere, on the land surface, and underground. It includes the study of the physical, chemical, and biological interaction of water with the rocks and minerals of the Earth, as well as its critical interaction with living organisms.

Careers in International Water Resources

Water resources is a dynamic profession worldwide. Every country must deal with water quantity and quality issues, and water affects every individual life on Earth.

Careers in Oceanography

Balancing on the deck of a research ship stationed a few miles out to sea; a crewman closes the vault-like door of a submersible. Two biologists share the submarine's rear passenger chamber, and two more share its front chamber.

Careers in Soil Science

Careers in soil science focus on understanding, managing, and improving soil and water resources. Soil science is a true interdisciplinary science that integrates the use of biology, chemistry, physics, geology, geography, climatology, hydrology, and mathematics to describe, interpret, and manage the soil and water environment.

Careers in Water Resources Engineering

Although physicians, attorneys, economists, and many other professionals often are primary players in developing and managing water resources, engineers play a significant role in water resources management. Potential employers include large and small businesses; government at all levels; corporations that are local to national and multinational in scope; and schools and universities.

Careers in Water Resources Planning and Management

Water resources careers in the early twenty-first century, particularly in planning and management, will offer great interest, large challenges, outstanding opportunities for peer recognition, and great personal satisfaction for young professionals. Rapid population growth, land-use changes, and perhaps global climatic change are among the factors that will place further demands on an already stressed global fresh-water supply and influence career directions of new water resource professionals.

Carson, Rachel

Rachel Carson made a career of her lifelong fascination with wildlife and the environment around her and became one of the pioneers of the environmental movement in the United States. Her mother taught her to enjoy the outdoors.

Cavern Development

Throughout time, humankind has been attracted to shelters and the dark mysteries of caverns, or caves. Much of the early evidence of humans and their art comes from archaeological sites in caves.