|JARVIE, H - Centre For Ecology And Hydrology|
|BOWERS, M - Centre For Ecology And Hydrology|
Submitted to: Agricultural and Environmental Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2017
Publication Date: 9/21/2017
Publication URL: https://handle.nal.usda.gov/10113/5832867
Citation: Smith, D.R., Jarvie, H.P., Bowers, M.J. 2017. Carbon, nitrogen, and phosphorus stoichiometry and eutrophication in River Thames Tributaries, UK. Agricultural and Environmental Letters. 2:170020. https://doi.org/10.2134/ael2017.06.0020.
Interpretive Summary: Algal blooms in surface waters, such as rivers, lakes and estuaries, depends largely on the availability of carbon, nitrogen and phosphorus. Generally, algae prefer a ratio of 106 carbon and 16 nitrogen for each 1 phosphorus, known as the Redfield Ratio. In this paper, we propose a method to graph the carbon to nitrogen to phosphorus ratio using data from five tributaries to the River Thames in the United Kingdom. The dissolved nutrient values in tributary water samples were used to determine the carbon to nitrogen to phosphorus ratio. The samples were then categorized based on the total phosphorus concentration as well as the chlorophyll-a concentration, which is a proxy for the amount of algae in the sample. Samples with a high amount of algae in them (more than 30 parts per billion chlorophyll-a) tended to only occur when the ration of total dissolved phosphorus accounted for 13% of the carbon to nitrogen to phosphorus ratio. This may provide researchers with a target level, below which algal blooms may be inhibited.
Technical Abstract: Primary productivity in aquatic systems relies on the availability of carbon (C), nitrogen (N) and phosphorus (P), with a preferred stoichiometric ratio of 106 C/16 N/1 P, known as the Redfield ratio. The intent of this paper is to present a methodology to visualize C/N/P stoichiometry and examine phytoplankton response. Redfield total dissolved C/N/P concentration ratios (TDC/TDNR/TDPR) from five River Thames tributaries were plotted in a ternary diagram, which allowed the relationships between nutrient stoichiometry, total phosphorus concentrations, and chlorophyll-a as a surrogate for phytoplankton biomass to be explored. Chlorophyll-a concentrations above 100 'g/L were not observed below 14% TDPR, and chlorophyll-a concentrations above 30 mg/L were not observed below 13% TDPR, a potential lower limit for highly eutrophic waters.