An examination of the factors involved in determining phosphatase activities in estuarine water. 1: Analytical procedures |
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Authors: | A L Huber D K Kidby |
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Institution: | (1) Department of Soil Science and Plant Nutrition, University of Western Australia, 6009 Nedlands, Western Australia |
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Abstract: | The effects of assay pH, magnesium addition, temperature, sodium azide, and of sample storage and filtration on the apparent
phosphatase activities in natural water bodies, and in particular estuaries, have been examined. Phosphatase activity was
assessed by monitoring the cleavage of p-nitrophenol from p-nitrophenyl phosphate (pNPP).
Magnesium concentrations in natural waters were found to be generally in excess of the requirement of the assay procedure.
Several pH maxima occurred for phosphatase activities in the estuarine waters examined. These optima were not constant with
respect to sampling stations or sampling time. This was considered to be, in part, the result of differences in the biomass
composition. Sample storage times and temperatures employed in the present study did not influence the phosphatase activities
of these low biomass waters. Phosphatase activities increased with increased incubation temperature. The rate of orthophosphate
release from pNPP during incubation was linear over time to 120 h. Sodium azide was found to be an adequate preservative when long incubation
times were required.
The effects of assay conditions are discussed in relation to the assay procedures and data interpretation. |
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Keywords: | phosphatase analytical procedures pH magnesium sample preservation estuarine |
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