Nature of dissolved P regenerated by plankton: implications for the ssPO(4) radiobioassay and for the nature of dissolved P

作者：Taylor William D^*

来源：Aquatic Sciences, 2010, 72(1): 13-20.

DOI：10.1007/s00027-009-0106-2

• Plankton
• Phosphorus regeneration
• Dissolved organic phosphorus

Techniques recently developed for measuring P regeneration, particulate P turnover, and PO4 (3-) concentration in lakewater assume that dissolved P-32 ((DP)-P-32) released by plankton is PO4 (3-). To test this assumption, I obtained samples of (DP)-P-32 regenerated from whole plankton communities by labeling the communities with P-32-PO4 (3-) then blocking re-uptake and transformation of regenerated (DP)-P-32 with two competitive inhibitors, unlabeled P-31-PO4 (3-) and pyrophosphate. Under these conditions, regenerated (DP)-P-32 accumulated and could be examined by gel chromatography to discern how much of it was P-32-PO4 (3-) versus higher molecular weight P compounds. I estimated that most or all of the (DP)-P-32 released was P-32-PO4 (3-). I also observed that the amount of DP observed on filtration of lakewater depended on the method employed to obtain the filtrate. Therefore, I also separated particulate P-32 from (DP)-P-32 with dialysis membrane (100,000 MW cutoff) without pressure. There was little DP larger than PO4 (3-) and no DP > 5,000 MW in the dialysate, leading me to conclude that DP < 100,000 MW was a minor component of both regenerated and total P. I suggest that under P-limited conditions that most dissolved P observed in lakewater filtrates may be intact viruses and cell constituents liberated in the filtration process. These results are mostly congruent with Lean's (J Fish Res Board Can 30:1525-1536, 1973) model of P-cycling in lake plankton, although the nature of "colloidal P" in Lean's model should be further investigated.

• 出版日期2010-1