Stream chemistry in the eastern United States: 1. Synoptic survey design, acid‐base status, and regional patterns

Abstract

To assess the regional acid-base status of streams in the mid-Atlantic and southeastern United States, spring base flow chemistry was surveyed in a probability sample of 500 stream reaches representing a population of 64,300 reaches (224,000 km). Approximately half of the streams had acid-neutralizing capacity (ANC) < 200 taeq L -1 . Acidic (ANC <-0) streams were located in the highlands of the Mid-Atlantic region (southern New York to southern Virginia, 2330 km), in coastal lowlands of the Mid-Atlantic (2600 km), and in Florida (462 kin). Acidic streams were rare (less than 1%) in the highlands of the Southeast. Inorganic monomeric aluminum (Alim) concentrations were highest in acidic streams of the Mid-Atlantic Highlands where over 70% of the acidic streams had Alim greater than !00 t•g L -1, a concentration above which deleterious biological effects have frequently been re13orted. Dissolved organic carbon concentrations were much higher in lowland coastal streams, compared with inland streams. Our data support a hypothesis that atmospheric sources and watershed retention control regional patterns in streamwater sulfate concentrations. Most stream watersheds retain the vast majority of the total nitrogen loading from wet deposition. The data suggest, however, that some deposition nitrogen may be reaching streams in the Northern Appalachians. These results show that acidic surface waters are found outside the glaciated northeastern portions of the United States and that watershed sulfate retention is not sufficient to prevent acidic conditions in some Mid-Atlantic Highlands streams. undertaken in the Northeast, Upper Midwest, Southeast [Linthurst et al., 1986], and mountainous areas of the West [Landers et al., 1987]. There remain, however, large areas in the Mid-Atlantic and Southeast where lakes are uncommon and where large numbers of streams with very low ANC are found. Despite the availability of a number of data sets collected at intensively studied stream research sites in the Mid-Atlantic and Southeast [Sharpe et al., 1984; Katz et al., 1985; Morgan and Good, 1988; Swank and Waide, 1988; Webb et al., 1989] and several stream surveys over small portions of these two regions [Silsbee and Larson, 1982; Lynch and Disc, 1985; Sharpe et al., 1987], no synoptic data sets existed prior to the recent National Stream Survey efforts from which a quantitative synoptic assessment could be made of the acid-base status of an explicitly defined population of streams in the Mid-Atlantic and Southeast. In the spring of 1986, the U.S. Environmental Protection Agency (EPA) conducted the National Stream Survey tNSS) on a probability sample of 446 streams in the mid-Atlantic and southeastern United States [Kaufmann et al., 1988; Sale et al., 1988]. This full-scale field effort was preceded a year earlier by a pilot survey of 54 streams in the Southern Blue Ridge. The pilot survey demonstrated the feasibility of the design, logistics, and analytical protocols used in the fullscale survey [Messer et al., 1986, 1988]. The objecti...

Assessment of chemical water types and their spatial variation using multi-stage cluster analysis, Queensland, Australia

“…Many are from the Northern Hemisphere, where low-pH rainfall is caused by sulfur-rich industrial emissions (e.g. Herlihy et al, 1991;Kaufmann et al, 1991). The above explanation is not, however, conclusive, as water analyses from South Africa (e.g.…”

A national critical loads framework for atmospheric deposition effects assessment: IV. Model selection, applications, and critical loads mapping

“…This approach, in itself, is flexible and can accommodate a range of levels of analyses. For example, simple regression analyses between deposition and surface water concentrations of nitrate can yield estimates about the deposition levels required to attain "nitrogen saturation" in forested ecosystems (Kaufmann andothers 1991, Stoddard 1992). As the linkages between the pollutant variable(s) and the indicator become more complex, multivariate analyses, principal component analyses, cluster analyses, or related techniques might be required to delineate statistical relationships among deposition and ecological effects.…”

Spatial Distribution of Acid-sensitive and Acid-impacted Streams in Relation to Watershed Features in the Southern Appalachian Mountains

“…In cases where multiple sample values were available, samples most nearly representing the spring of 1995 were selected. Spring season was chosen as an index of base flow chemistry, as was done in the US EPA's National Stream Survey, because it is generally reflective of the lowest seasonal ANC values and because sensitive life stages (eggs and young) are present for many fish species (Kaufmann, Herlihy, Mitch, Messer, & Overton, 1991). Stream ANC has in this region changed little since the early 1990s .…”