Journal article
Elevated Nitrogen and Phosphorus Concentrations in Urbanizing Southwest Washington Streams
Northwest science, Vol.86(4), pp.237-247
09/01/2012
Handle:
https://hdl.handle.net/2376/123645
Abstract
In southwest Washington, rapid population growth and associated land use change have resulted in elevated stream nutrient concentrations. To evaluate the extent and nature of human alterations to stream nutrient concentrations in this region, we compiled four water years of total phosphorus (TP) and dissolved inorganic nitrogen (DIN) data from two long-term monitoring programs. We also quantified watershed characteristics likely to affect aquatic nutrient loading, and tested for correlations between these characteristics and stream nutrient concentrations. Average nutrient concentrations in study streams were significantly elevated relative to EPA recommended nutrient criteria in all sites for DIN and in nine out of 14 sites for TP. Of the watershed characteristics investigated, percent "impervious" (+) and percent "forested" (-) were the best predictors of TP concentration (R-2 = 0.41 and 0.64, respectively, + and - indicate the slope of the regression). Percent "developed" (+) and percent "forest and woody wetland" (-) were the best predictors of DIN concentration (R-2 = 0.75 and 0.73, respectively). In urban streams, the mean dry season DIN concentration was significantly higher than the mean wet season DIN concentration, but this pattern was reversed in less urban watersheds. Urban streams also had significantly higher DIN than non-urban streams. The strong relationship between DIN and "developed land" suggests that as southwest Washington's population continues to grow, targeted N management will become increasingly important. The strong negative relationship between "forest and woody wetland" and both TP and DIN concentration suggests that this land use type is particularly important in reducing stream nutrient loading.
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Details
- Title
- Elevated Nitrogen and Phosphorus Concentrations in Urbanizing Southwest Washington Streams
- Creators
- Bridget Deemer - Washington State UniversityKara Goodwin - Washington State University VancouverTammy Lee - Washington State University VancouverM. Keith Birchfield - Washington State University VancouverKassi Dallavis - Washington State University VancouverJosh Emerson - Washington State University VancouverDawn Freeman - Washington State University VancouverErica Henry - Washington State University VancouverLouise Wynn - Washington State University VancouverJohn Harrison - Washington State University Vancouver
- Publication Details
- Northwest science, Vol.86(4), pp.237-247
- Academic Unit
- Harrison Research Group: Global Change and Watershed Biochemistry ; Environment, School of the (CAS)
- Publisher
- NORTHWEST SCIENTIFIC ASSOC
- Number of pages
- 11
- Identifiers
- 99900668009501842
- Language
- English
- Resource Type
- Journal article