Chemical Characterization of Soluble Phosphorus Forms along a Hydrologic Flowpath of a Forested Stream Ecosystem
- ORNL
The concentration and distribution of soluble phosphorus (P) forms were determined in compartments of a hydrologic pathway in a forested watershed (Walker Branch, Tennessee). 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 and total soluble phosphorus (SRP and TSP). Soluble unreactive P (SUP) was determined from their difference. An increase of TSP from rainfall to throughfall indicated leaching or wash off of P from the canopy. SRP and SUP decreased markedly as water percolated through the soil, suggesting biological uptake and/or geochemical adsorption of phosphate groups on soil particles. Changes in soluble P. concentrations within the stream channel supported previous evidence for biological control of P dynamics in Walker Branch. Overall, SUP (an estimate of soluble organic P) constituted a significant fraction of the total soluble P present in each compartment of the flowpath. An analytical technique using high-performance liquid chromatography (HPLC) to separate the inositol phosphates (IP's) was developed and used in characterizing organic P fractions of natural systems. Commercial orthophosphate, 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 technique was used to separate an enzyme hydrolysate mixture of IP's into five components. IHP was separated from PO{sub 4} and IMP in a wheat bran extract using the HPLC method. Alkaline bromination was used to extract IP's from a Walker Branch soil sample and HPLC was used to examine the extract; at least three IP peaks were recognized. Using the HPLC technique, an attempt was made to detect the presence of IP's in a Walker Branch groundwater sample concentration by ultrafiltration. The concentration process was unsuccessful possibly due to filtration membrane leakage, so no peaks were detected. The HPLC developmental work indicated the potential usefulness of this technique in characterizing soluble organic P compounds in natural waters, leading to the identification of the inositol phosphates.
- Research Organization:
- ORNL Oak Ridge National Laboratory (US)
- Sponsoring Organization:
- OHER, DOE (US)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 814417
- Report Number(s):
- ORNL/TM-9737
- Country of Publication:
- United States
- Language:
- English
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