Using oxygen isotopes for tracing phosphate sources at the catchment level
Abstract
In the last 50 years, the use of phosphate and nitrate fertilizers has dramatically increased producing serious environmental consequences and enhancing the consumption of limited resources. Tracing P has always been a complicated endeavor, since once that P is dissolved as orthophosphate, P derived from different sources (e.g., soil, fertilizer, plant residues) cannot be distinguished one from the other. Due to safety concerns, radioisotopes such as 32P and 33P, are currently used to study the dynamics and transfers of P in the soil and plant system only in laboratory and greenhouse experiments. P has only one stable isotope (31P), so contrary to nitrogen or carbon or sulfur, a stable isotopes approach was not considered as a possible venue for P studies. For this reason, the research community involved in environmental studies put many hopes into the use of oxygen isotopes in phosphate (18O-P). At present, the main application of oxygen isotopes in the environment is understanding and providing more insights into the biological P cycle, but not tracing fluxes and transfers of P in the environment. This is because enzyme activity, which promotes the exchange of oxygen between phosphate and water, can be so extensive to completely erase a source signal. Throughout the years, we have collected 18O-P signatures of mineral fertilisers and animal manures with the goal to build a database of P sources to the environment. At the same time, the use of 18O-P for tracing sources of P has been re-evaluated. Under specific conditions, this tracer could be used to identify sources of P and differentiate between transport/transfer of P and biological transformations at the catchment scale.
- Publication:
-
EGU General Assembly Conference Abstracts
- Pub Date:
- April 2019
- Bibcode:
- 2019EGUGA..21.9583T