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Alkaline Phosphatase Activity in the Sediment‐Water Column of a Hypereutrophic Lake
Author(s) -
Newman S.,
Reddy K. R.
Publication year - 1993
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1993.00472425002200040028x
Subject(s) - chemistry , alkaline phosphatase , anoxic waters , environmental chemistry , water column , mineralization (soil science) , phosphatase , anaerobic exercise , sediment , organic matter , acid phosphatase , hydrolysis , total organic carbon , biochemistry , ecology , enzyme , nitrogen , biology , organic chemistry , physiology , paleontology
Inorganic P limitation in many aquatic systems may be overcome through the enzymatic hydrolysis of organic P compounds. The objective of our study was to determine the effect of dissolved oxygen (DO) of the water column and redox (Eh) status of the sediments on alkaline phosphatase activity (APA) in a shallow hypereutrophic lake located in central Florida. Alkaline phosphatase activity was used as an index of potential organic P mineralization. Lake water was incubated in the dark under aerobic and anaerobic conditions for 24 h. Under aerobic conditions APA increased from 22 to 43 nM min −1 within 24 h. Under anaerobic conditions no significant change in APA was observed. Neither total soluble P nor soluble‐reactive P exhibited significant responses to anoxic conditions in the water column. The increase in APA observed under aerobic conditions was attributed to increased plankton metabolic P demand following depletion of internal cell P. Sediments were incubated under six different Eh levels for 30 d. In combination with APA measurements, sediment organic P was fractionated into labile and nonlabile pools using selected inorganic chemical extractants. Phosphatase hydrolysis of organic P was significantly inhibited under anaerobic conditions. Alkaline phosphatase activity was positively related to pE + pH ( r = 0.90). Conversely, porewater organic P was inversely correlated with pE + pH ( r = −0.92). Alkaline phosphatase activity was also inversely related to porewater organic P ( r = −0.95), labile organic P ( r = −0.81), and humic acid P ( r = −0.74). The results of this study suggest that short‐term depletion of DO will not affect the enzymatic breakdown of organic P within the water column. Significant reduction in the alkaline phosphatase‐dependent hydrolysis of sedimentary organic P will occur under anaerobic conditions; hence, P cycling in highly organic sediments may be severely inhibited.