Analysis of nitrogen and phosphorus nutrients in lake sediment

Author

Kelsey L. Berrier, James Madison UniversityFollow

Creative Commons License

This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Date of Graduation

Spring 2015

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Department of Chemistry and Biochemistry

Advisor(s)

Daniel M. Downey

Abstract

Analytical methods for the determination of nitrogen and phosphorus nutrients (NO₃-N, NH₄-N and PO₄-P) in sediment were studied with the goal of developing extraction steps compatible with analysis by ion chromatography (IC). Research focused on extractant solution composition, Dionex OnGuard^® sample pretreatment cartridges for salt removal, and chromatographic resolution. Aqueous test samples, lake sediment samples and spiked lake sediment samples were analyzed. Dionex Ag, Ag/H, and H cartridges were studied for the pretreatment step. Silver (Ag) cartridges were found effective in removing >99% of interfering chloride ion to allow NO₃-N determination by anion IC when 2 M KCl was used for sediment extraction. Ag cartridges were found to react and remove NH₄-N, so an alternative extraction solution of 0.02 M SrCl₂ was studied. Extraction by 0.02 M SrCl₂ enabled anion IC analysis of NO₃-N and cation IC analysis of NH₄-N without further sample treatment, but this extraction method gave significantly lower values of nutrient (p < 0.05) than 2 M KCl extraction. Alternative chromatographic parameters utilizing increased eluent concentration were employed for the detection of NO₃-N in sediment with interfering sulfate ion due to improved resolution of nitrate and sulfate peaks. Extraction with 0.02 M SrCl₂ coupled to cation IC and phenate colorimetric methods gave similar results for NH₄-N analysis in some sediments (p > 0.05), which demonstrated that the extraction step was the determining factor in nutrient analysis. Analysis of total phosphorus in the form of PO₄-P was precluded by high sulfate and nitrate concentrations required for acid digestion of extracted sediment. Additional research is needed to develop IC methodology for NO₃-N, NH₄-N and PO₄-P.

Recommended Citation

Berrier, Kelsey L., "Analysis of nitrogen and phosphorus nutrients in lake sediment" (2015). Senior Honors Projects, 2010-2019. 70.
https://commons.lib.jmu.edu/honors201019/70