The reservoir behind the Three Gorges Dam will stretch more than 600 kilometers upstream, submerging towns, factories, mines, and archaeological sites. View image
In many cities, current concentrations of particulate matter exceed the limit values established by the European Union. In the first 3 months of 2005, for example, the daily limit value was exceeded on more than 30 days in several German cities. View image
When the Automeris moth perceives a threat, it moves its forewings to reveal false eye spots on its hindwings and to frighten predators away. View image
This backpack monitoring system, designed for studying exposure to air pollution, includes several pollutant detectors, a sampling pump, and a handheld Global Positioning System receiver. View image
As early photosynthesis began to raise atmospheric oxygen levels about 2.7 billion years ago, iron precipitated out of seawater, creating banded iron formations like this specimen from Ontario, Canada. View image
Water flows continuously into the Berkeley Pit from surface runoff and groundwater seepage. To prevent the pit from contaminating surface aquifers, the cleanup plan calls for pumping and treating water from the pit to keep the water surface at a safe level. View image
The Dust Bowl stimulated interest in conservation tillage methods, which leave crop residues in place to reduce soil erosion and prevent topsoil loss. View image
Thanks to mandatory emission limits, catalytic converters have become standard pollution control features on passenger cars over the past several decades. View image
Farmers have practiced green manuring for centuries, but the technique has become more sophisticated with growing understanding of soil ecology, plant biochemistry, and nutrient cycling. View image
Zebra mussels can survive in many aquatic environments and breed prolifically. Originally found in Russia, they have spread throughout the Great Lakes and the Mississippi, Ohio, Tennessee, and Hudson river basins. View image
Commercial fishing is one of the most dangerous occupations in the United States, but fishermen can make tens of thousands of dollars for one to three months' work. These rates represent a risk premium that is required to attract workers. View image
Large hog farms may house 10,000 or more hogs indoors for their entire life spans. On many U.S. farms, breeding sows are kept for weeks at a time in individual crates too narrow for the animals to turn around. View image
Along with wheat, maize (corn), and potatoes, rice is one of the world's most important staple foods. These foods contain widely varying levels of many important micronutrients. Golden rice is designed to eliminate one deficiency by producing vitamin A in its grains. View image
These corals will die unless the algal symbionts quickly repopulate the coral. Most scientists believe that usually warm sea surface temperatures are at least partially responsible for regional bleaching events. View image
Geologist Paul Hoffman points out glacial dropstones, small rounded pebbles imbedded in otherwise neat layers of sedimentary rock 500-600 million years old. View image
On a feedlot, young beef cattle are grown to market weight on a diet that consists primarily of grain. Cattle that are fed grain reach market size at about 14 months of age, compared to 18 to 24 months for grass-fed beef, but raising cattle on grain is much more energy-intensive. View image
Damage along the Gulf Coast from Hurricane Katrina in 2005 may be a preview of impacts in other low-lying regions as sea levels rise and storms become more frequent. View image
Kimberella was originally thought to be a type of jellyfish, but scientists now believe that it had rigid parts (probably a hard, shell-like covering) which formed the deep depressions in these fossils. View image
The Framingham Heart Study was designed to identify general causes of heart disease and stroke. Researchers have published more than 1,000 scientific papers on risk factors for cardiovascular disease based on Framingham data. View image
Haze pollution can drastically reduce visibility, even at locations like Acadia National Park that are far downwind from aerosol pollution sources. View image
The Carrie blast furnaces were built in the early 1900s and operated until 1983. Two remaining furnaces have been designated as national historic landmarks. View image
A small settlement just north of the border between Egypt and Sudan taps an underground aquifer to support farming in the desert. Each dark spot is an irrigated crop circle about 1 kilometer across. View image
Clearing land for agriculture reduces the Amazon region’s ability to sequester carbon from the atmosphere, thus furthering global climate change. View image
Invasive salt cedar along the Forgotten River segment of the Rio Grande in Hudspeth County, Texas and Chihuahua State, Mexico. Yellow areas indicate high probability of salt cedar infestation. View image
Archaeopteryx had some features not seen in today's birds, such as a long bony tail and a full set of teeth. However, it also had feathers, wings, and reduced fingers, which are characteristic of modern birds. View image
Offshore drilling rigs are hundreds of feet high and weigh many thousands of tons. A single drilling platform can cost more than $1 billion. View image
Ozone can stunt plant growth, produce mottled leaves and needles, suppress flower and bud formation, and make plants more vulnerable to fungal infections. View image
Since they were reintroduced to Yellowstone National Park in 1995, gray wolves have reduced the number of elk and other prey species, with impact further down through the park's food web. View image
Dwarf plants have relatively thick stems and are less likely to lodge (fall over under the weight of the grain they carry). A low-tillering plant is one with fewer stalks at the bottom. View image
Excess sediments can clog river channels and damage wildlife habitat. If sediments are contaminated with pesticides or industrial chemicals, they can also reduce water quality and introduce hazardous substances into the food chain. View image
Some U.S. states and electric power companies offer rebates for installing home solar systems, which reduce peak demand for electricity and help avoid the need to build new generating facilities. View image
Stromatolites are uncommon today because burrowing and grazing organisms destabilize marine sediments and consume the microbial mats produced by cyanobacteria. Exceptions occur in hyper-saline environments, like Shark Bay, where few organisms can survive. View image
Located between Colorado’s two largest cities, Denver and Colorado Springs, Douglas County has been among the fastest-growing counties in the United States in recent years. View image
The Willamette Meteorite is probably a fragment from the core of an ancient planet that broke up as it orbited the sun. Its structure suggests that it sustained at least two high-energy impacts in space before it fell to Earth's surface and weathered further. View image
Tomato frogs, which are found only along the northern coast of Madagascar, are endangered by habitat destruction and over-collecting for sale as pets. View image
Director of the Center for Tropical Forest Science at the Smithsonian Tropical Research Institute,
Stuart Davies explains the symbiotic relationship between ants and a cecropia plant. View image
Specific functions vary with each site's vegetation, geology, and hydrologic patterns, but wetlands typically perform a number of purifying functions. View image
Some researchers believe that fuel cells could eventually
replace internal combustion engines. But converting to
hydrogen for transportation would require the
development of a new fleet of fuel-cell vehicles,
efficient methods for producing hydrogen on a large
scale, and a hydrogen storage and distribution system. View image
Chemical plants near the Palos Verdes Peninsula south of Los Angeles discharged contaminated sewage until the early 1970s. State agencies closed the local fishery for white croaker in 1990 due to health risks from eating fish contaminated with PCBs and pesticides. View image
Many clean energy applications are not limited to more-developed countries, but can also be used in rural and other areas that lack modern infrastructure. View image
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