Collecting pieces or specimens or making measurements or observations at determined intervals or areas. Results may be used as representative of the whole research area or population.
Explains acidity and acid rain and how it affects aquatic organisms. Describes the effect of acid rain on this national park, identifying areas that are at greater or lesser risk from acid rain.
Overview of the Toxic Substances Hydrology Program role in investigating the occurrence and fate of agricultural chemicals with links to investigations, headlines, on-line fact sheets, new publications, bibliographies and photo gallery.
Using genetic analysis of organic material found in aquatic environments it is possible to detect the presence of organisms without necessarily observing or capturing individuals. Explains terms, methods, and prospective utility of this approach.
Information on arsenic in United States ground water largely as a result of minerals dissolving from weathered rocks and soils. Includes links to publications, data, maps, and links to other sites with information on arsenic.
Well vulnerability results from the young age of groundwater. Karst features permit contaminants to move into the aquifer easily, leading to a well mixed aquifer; geochemical processes do not degrade contaminants quickly.
Previous analysis showed this area to have reduced macroinvertebrate biodiversity, an important measure of ecosystem health. New observations indicate that conditions have improved; report includes methods and results of sampling.
Maps and information about potential spread of avian influenza in migratory birds in Alaska. Includes descriptions and photos of the waterfowl that are being monitored.