Abstract. The exchange rate of inorganic phosphorus (P) between the soil solution and solid phase, also known as soil solution P turnover, is essential for describing the kinetics of bioavailable P. While soil solution P turnover (Km) can be determined by tracing radioisotopes in a soil–solution system, few studies have done so. We believe that this is due to a lack of understanding on how to derive Km from isotopic exchange kinetic (IEK) experiments, a common form of radioisotope dilution study. Here, we provide a derivation of calculating Km using parameters obtained from IEK experiments. We then calculated Km for 217 soils from published IEK experiments in terrestrial ecosystems, and also that of 18 long-term P fertilizer field experiments. Analysis of the global compilation data set revealed a negative relationship between concentrations of soil solution P and Km. Furthermore, Km buffered isotopically exchangeable P in soils with low concentrations of soil solution P. This finding was supported by an analysis of long-term P fertilizer field experiments, which revealed a negative relationship between Kmand phosphate-buffering capacity. Our study highlights the importance of calculating Km for understanding the kinetics of P between the soil solid and solution phases where it is bioavailable. We argue that our derivation can also be used to calculate soil solution turnover of other environmentally relevant and strongly sorbing elements that can be traced with radioisotopes, such as zinc, cadmium, nickel, arsenic, and uranium.
For the full text please follow the link: https://www.biogeosciences.net/15/105/2018/
I would just like to say a quick hello as the new administrator of the soil phosphorus forum. If you have any posts or requests please get in touch.
The Environmental Biogeochemistry Laboratory (http://sites.udel.edu/ebl/) at the University of Delaware has openings for two graduate students and a postdoctoral researcher. A short description of the positions and benefits is included below:
- Graduate students
- i) Source tracking of phosphorus in a watershed. It requires general background in soil chemistry, biogeochemistry, and watershed scale processes. Experience on stable isotopes (P and N) or nutrient cycling in a watershed is a plus.
- ii) Residual and recalcitrant phosphorus in soil. It requires background on soil sciences/chemistry, geochemistry or related discipline.
Candidates are for PhD degree. A 12-month research assistantship of ~$25,000 will be paid to graduate students. Graduate application has be made through UD (http://grad.udel.edu/apply/). Successful candidates are anticipated to start late summer or Fall.
- Postdoctoral associate
Fate of phytate in the environment. Phytate and other inositol phosphates in soils: detection, quantitation, and degradation and address the longstanding question on accumulation vs decomposition of phytate in the environment. A recent Ph.D. in soil sciences, chemistry or related discipline from an accredited university is required. Candidate must have knowledge and experience in one or more of the following research techniques: ion chromatography, stable isotopes, 1 and 2-D NMR spectroscopy, stereochemistry, and enzymology, and a proven record through scientific publications. Candidate must be willing to learn other research technique from his/her own expertise.
A 12-month salary of $48,000 will be paid to the postdoctoral associate. University of Delaware offers a generous health insurance and other benefits. See http://www1.udel.edu/Benefits/ for complete details of the benefit package.
Interested candidates for both positions are advised to contact Deb Jaisi (email@example.com) for further information.
August 20-24, 2017
Litomyšl Chateau, Czech Republic
You are cordially invited to BIOGEOMON 2017, to be held next summer at the UNESCO World Cultural Heritage Site of Litomyšl, Czech Republic.
The symposium will focus on biogeochemistry in an era of global change. Long-term trends in ecosystem functioning and stoichiometry of biogeochemical processes in upland and wetland soils will be emphasized, along with catchment monitoring/modelling, and translocations of nutrients, micronutrients and trace metals in forest ecosystems, grasslands and extreme environments. We look forward to seeing you in the lovingly restored 16th century town of Litomyšl.