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Assessment of a δ 15 N Isotopic Method to Indicate Anthropogenic Eutrophication in Aquatic Ecosystems
Author(s) -
Cole Marci L.,
Valiela Ivan,
Kroeger Kevin D.,
Tomasky Gabrielle L.,
Cebrian Just,
Wigand Cathleen,
McKinney Richard A.,
Grady Sara P.,
Carvalho da Silva Maria Helena
Publication year - 2004
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2004.1240
Subject(s) - macrophyte , environmental science , eutrophication , wastewater , spartina alterniflora , nutrient , water column , ecosystem , aquatic ecosystem , food web , water quality , aquatic plant , environmental chemistry , hydrology (agriculture) , ecology , environmental engineering , wetland , chemistry , marsh , biology , geotechnical engineering , engineering
Increased anthropogenic delivery of nutrients to water bodies, both freshwater and estuarine, has caused detrimental changes in habitat, food web structure, and nutrient cycling. Nitrogen‐stable isotopes may be suitable indicators of such increased nutrient delivery. In this study, we looked at the differences in response of macrophyte δ 15 N values to anthropogenic N across different taxonomic groups and geographic regions to test a stable isotopic method for detecting anthropogenic impacts. Macrophyte δ 15 N values increased with wastewater input and water‐column dissolved inorganic nitrogen (DIN) concentration. When macrophytes were divided into macroalgae and plants, they responded similarly to increases in wastewater N, although macroalgae was a more reliable indicator of both wastewater inputs and water‐column DIN concentrations. Smooth cordgrass ( Spartina alterniflora Loisel.) δ 15 N increased uniformly with wastewater inputs across a geographic range. We used the relationship derived between S. alterniflora and relative wastewater load to predict wastewater loads in locations lacking quantitative land use data. The predictions matched well with known qualitative information, proving the use of a stable isotopic method for predicting wastewater input.