Chemical characterization of soluble phosphorus forms along a hydrologic flowpath of a forested stream ecosystem

Author

Julie E. Segars

Date of Award

12-1985

Degree Type

Thesis

Degree Name

Master of Science

Major

Chemistry

Major Professor

Richard M. Pagni, Roger A. Minear

Committee Members

Stephen E. Herbes, Michael J. Sepaniak

Abstract

The concentration and distribution of soluble phosphorus forms were determined among compartments of a hydrologic pathway in a forested watershed (Walker Branch, Tenn.). Rainfall, throughfall, soil water, groundwater, stream water, and water from two sites in Melton Hill Reservoir downstream of Walker Branch were examined for soluble reactive phosphorus (SRP) and total soluble phosphorus (TSP). Soluble unreactive phosphorus (SUP) was determined from their difference. An increase of TSP from rainfall to throughfall indicated leaching and/or wash-off of phosphorus from the canopy. SRP and SUP decreased markedly as water percolated through the soil, suggesting bio logical uptake and/or geochemical adsorption of the phosphate groups on soil particles. The temporal pattern of SRP in the upstream site (with a maximum in the summer and a minimum in mid-autumn) and the decrease in SRP and the increase in SUP from upstream to downstream within the stream channel supported previous evidence for biological control of phosphorus dynamics in Walker Branch. Overall, SUP (an estimate of soluble organic phosphorus) constituted a significant fraction of the TSP present in each compartment of the flowpath.

An analytical technique using high-performance liquid chromatography (HPLC) to separate the inositol phosphates (IPs) was developed and used in characterizing organic phosphorus fractions of natural systems. Commercial orthophosphate (PO₄^3-), inositol monophosphate (IMP), and inositol hexaphosphate (IHP) were adequately separated from each other on Aminex A-27 resin using a sodium chloride/tetrasodium EDTA gradient elution. The HPLC technique was also used to separate an enzyme hydrolysate mixture of IPs into five components, to separate IHP from PO₄^3- and IMP in an extract of wheat bran, and to examine an alkaline brominated extract of a Walker Branch soil sample, where at least three IP peaks were recognized. Using the HPLC technique, an attempt was made to detect the presence of IPs in a Walker Branch groundwater sample concentrated by membrane ultrafiltration. The concentration process was unsuccessful, possibly due to membrane leakage, so no peaks were detected. The HPLC developmental work indicated that this technique potentially could be used to examine natural waters for the presence of IPs.

Recommended Citation

Segars, Julie E., "Chemical characterization of soluble phosphorus forms along a hydrologic flowpath of a forested stream ecosystem. " Master's Thesis, University of Tennessee, 1985.
https://trace.tennessee.edu/utk_gradthes/14438