Chemical Characteristics of Streams in the Mid-Atlantic and Southeastern United States (National Stream Survey: Phase 1). Volume 1. Population Descriptions and Physico-Chemical Relationships

摘要

National Stream Survey Phase I (NSS-I) field activities were conducted in the Mid-Atlantic and Southeastern U.S. in the spring of 1986 by the U.S. EPA as part of the National Surface Water Survey and the National Acid Precipitation Assessment Program. The Survey employed a probability sample of 500 stream reaches representing a regional population of 64,700 reaches portrayed as blue lines on 1:250,000 scale maps and which have drainage areas less than 155 sq km. The NSS-I design allows regional extra-polation, with known confidence, of the number and total length of reaches with specified chemical characteristics. Excluding Florida, the Southeastern subregions of the NSS-I were estimated to contain very few acidic (ANC less than 0) reaches. Acidic reaches were found primarily in lowland reaches of Florida and the Mid-Atlantic Coastal Plain and in upland reaches of the Mid-Atlantic subregions. Sulfate concentrations were markedly higher in the Mid-Atlantic than in the Southeast. Analysis of ion composition and evidence of stream acidification are presented.