Geography

Nitrogen and phosphorus concentrations in forest streams of the United States

Document Type

Article

Abstract

Seventy to eighty percent of the water flowing in rivers in the United States originates as precipitation in forests. This project developed a synoptic picture of the patterns in water chemistry for over 300 streams in small, forested watersheds across the United States. Nitrate (NO3-) concentrations averaged 0.31 mg N/L, with some streams averaging ten times this level. Nitrate concentrations tended to be higher in the northeastern United States in watersheds dominated by hardwood forests (especially hardwoods other than oaks) and in recently harvested watersheds. Concentrations of dissolved organic N (mean 0.32 mg N/L) were similar to those of NO3-, whereas ammonium (NH4+) concentrations were much lower (mean 0.05 mg N/L). Nitrate dominated the N loads of streams draining hardwood forests, whereas dissolved organic N dominated the streams in coniferous forests. Concentrations of inorganic phosphate were typically much lower (mean 12 mg P/L) than dissolved organic phosphate (mean 84 mg P/L). The frequencies of chemical concentrations in streams in small, forested watersheds showed more streams with higher NO3- concentrations than the streams used in national monitoring programs of larger, mostly forested watersheds. At a local scale, no trend in nitrate concentration with stream order or basin size was consistent across studies.

Publication Title

Journal of the American Water Resources Association

Publication Date

1-1-2004

Volume

40

Issue

5

First Page

1277

Last Page

1291

ISSN

1093-474X

DOI

10.1111/j.1752-1688.2004.tb01586.x

Keywords

forest hydrology, nonpoint source pollution, stream water quality, synopsis, watershed management

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