HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Sutter, B. Articles by Ming, D. W. Search for Related Content PubMed Articles by Sutter, B. Articles by Ming, D. W. Agricola Articles by Sutter, B. Articles by Ming, D. W. Related Collections Zeoponics Kinetics Soil Chemistry

Division S-2—Soil Chemistry

Dissolution Kinetics of Iron-, Manganese-, and Copper-Containing Synthetic Hydroxyapatites

^a Dep. of Soil and Crop Sciences, Texas A&M Univ., College Station, TX 77843
^b NASA Johnson Space Center, Houston, TX 77058
^c SETI Institute, NASA Ames Research Center, Moffett Field, CA 94035

^* Corresponding author (bsutter{at}mail.arc.nasa.gov)

Micronutrient-substituted synthetic hydroxyapatite (SHA) is being evaluated by the National Aeronautics and Space Administration's (NASA) Advanced Life Support (ALS) Program for crop production on long-duration human missions to the International Space Station or for future Lunar or Martian outposts. The stirred-flow technique was utilized to characterize Ca, P, Fe, Mn, and Cu release characteristics from Fe-, Mn-, and Cu-containing SHA in deionized (DI) water, citric acid, and diethylene-triamine-pentaacetic acid (DTPA). Initially, Ca and P release rates decreased rapidly with time and were controlled by a non-SHA calcium phosphate phase(s) with low Ca/P solution molar ratios (0.91–1.51) relative to solid SHA ratios (1.56–1.64). At later times, Ca/P solution molar ratios (1.47–1.79) were near solid SHA ratios and release rates decreased slowly indicating that SHA controlled Ca and P release. Substituted SHA materials had faster dissolution rates relative to unsubstituted SHA. The initial metal release rate order was Mn >> Cu > Fe which followed metal-oxide/phosphate solubility suggesting that poorly crystalline metal-oxides/phosphates were dominating metal release. Similar metal release rates for all substituted SHA (approximately 0.01 cmol kg^–1 min^–1) at the end of the DTPA experiment indicated that SHA dissolution was supplying the metals into solution and that poorly crystalline metal-oxide/phosphates were not controlling metal release. Results indicate that non-SHA Ca-phosphate phases and poorly crystalline metal-oxide/phosphates will contribute Ca, P, and metals. After these phases have dissolved, substituted SHA will be the source of Ca, P, and metals for plants.

Abbreviations: ALS, advanced life support • DI, deionized • DTPA, diethylene-triamine pentaacetic acid • EPR, electron paramagnetic resonance • SHA, synthetic hydroxyapatite