Rapid biologically mediated oxygen isotope exchange between water and phosphate
Tóm tắt
In order to better constrain the rate of oxygen isotope exchange between water and phosphate via biochemical reactions a set of controlled experiments were conducted in 1988 at the Aquaculture Plant in Elat, Israel. Different species of algae and other organisms were grown in seawater tanks under controlled conditions, and the water temperature and oxygen isotopic composition (δ18Ow) were monitored. The oxygen isotopic composition of phosphate (δ18Op) in the organisms' food source, tissues, and the δ18Op of dissolved inorganic phosphate (DIP) were measured at different stages of the experiments. Results indicate that intracellular oxygen isotope exchange between phosphorus compounds and water is very rapid and occurs at all levels of the food chain. Through these reactions the soft tissue δ18Op values become 23–26‰ higher than δ18Ow, and δ18Op values of DIP become ∼20‰ higher than δ18Ow. No correlation between δ18Op values and either temperature or P concentrations in these experiments was observed. Our data imply that biogenic recycling and intracellular phosphorus turnover, which involves kinetic fractionation effects, are the major parameters controlling the δ18Op values of P compounds dissolved in aquatic systems. This information is fundamental to any application of δ18Op of dissolved organic or inorganic phosphate to quantify the dynamics of phosphorus cycling in aquatic systems.
Từ khóa
Tài liệu tham khảo
Afghan B. K., 1982, in Chemical Analysis of Inorganic Constituents of Water, 131
Avron M., 1964, The fate of phosphate oxygen in photophosphorylation, J. Biol. Chem., 240, 1381, 10.1016/S0021-9258(18)97587-3
Brodskii A. I., 1953, Isotope exchange of oxygen in solutions of phosphate acids, Dokl. Acad. Nauk, 92, 589
Colman A. S., 2000, A new technique for the measurement of phosphate oxygen isotopes of dissolved inorganic phosphate in natural waters, Eos Trans. AGU, 81, abstract B51A‐0
Dahms A. S., 1973, Occurrence and characteristics of 18O exchange reactions catalyzed by sodium‐ and potassium‐dependent adenine triphosphate, J. Biol. Chem., 248, 3155, 10.1016/S0021-9258(19)44021-0
Kolodny Y., 1986, in The Scientific Study of Flint Chert
Luz B., 1984, Fractionation of oxygen isotopes between mammalian bone‐phosphate and environmental drinking water, Geochim. Cosmochim. Acta, 63, 855
McLaughlin K., 2000, Towards a proxy for phosphate recycling in marine ecosystems, Eos Trans. AGU, 81, abstract B51A‐0
O'Neil J. R., 2001, Effects of speciation on equilibrium fractionations and rates of oxygen isotope exchange between (PO4)aq and H2O
Paytan A. Oxygen isotope variations of phosphate in aquatic systems MS. thesis Hebrew Univ. Jerusalem 1989.
Stern J. C., 2000, Determining the source of phosphate in the Everglades, Eos Trans. AGU, 81, abstract B51A‐0
Strickland J. D. H., 1972, A Practical Handbook of Seawater Analysis, 45