Federica Tamburini

ETH Zurich | ETH Zürich · Department of Environmental Systems Science

Soil phosphorus (P) directly impacts major sustainability outcomes, namely crop yields, water quality, and carbon sequestration. Optimally managing P to improve sustainability outcomes requires a mechanistic understanding of P availability and transfer, alongside high-resolution spatial data. However, it is unclear if current measurement techniques...

This chapter provides an overview of how the stable isotope composition of oxygen bond to phosphorus, δ ( ¹⁸ O) PO4 , in phosphate can be used to investigate P cycling in the soil–plant continuum. In recent years, several books and articles about different aspects of P cycling have been published. This chapter provides summary information about P c...

Soils in hyper‐arid climates, such as the Chilean Atacama Desert, show indications of past and present forms of life despite extreme water limitations. We hypothesize that fog plays a key role in sustaining life. In particular, we assume that fog water is incorporated into soil nutrient cycles, with the inland limit of fog penetration corresponding...

The oxygen isotopes ratio (δ¹⁸O) of microbial cell water strongly controls the δ¹⁸O of cell phosphate and of other oxygen-carrying moieties. Recently it was suggested that the isotopic ratio in cell water is controlled by metabolic water, which is the water produced by cellular respiration. This potentially has important implications for paleoclima...

The oxygen isotope ratio of phosphates is a powerful tool to study phosphorus in the soil‐plant system. In the past two decades, the scientific community has made substantial progress in characterizing biogeochemical processes that lead to an alteration of oxygen isotope ratios in phosphates and in evaluating oxygen isotope ratios of phosphates in...

In this chapter, we focus on low atomic mass stable isotopes that are widely used in soil and environmental studies. These include carbon (C), nitrogen (N), oxygen (O), and sulfur (S). We elucidate how such stable isotopes are used to infer processes, estimate mean residence time of an element in an environmental compartment, and identify sources...

Dietary deficiency of selenium is a global health threat related to low selenium concentrations in crops. Despite the chemical similarity of selenium to the two more abundantly studied elements sulfur and arsenic, the understanding of its accumulation in soils and availability for plants is limited. The lack of understanding of soil selenium cyclin...

The oxygen isotopic composition of phosphate (δ¹⁸OP) in soils and surface water bodies has been used to trace terrestrial P inputs into aquatic ecosystems. However, enhanced biological activity in vegetated riparian buffer strips (VBSs) may lead to an alteration of δ¹⁸OP values. The objective of this study was to assess whether enhanced biological...

The chemical nature of most organic P (Porg) in soil remains ‘unresolved’ but is accounted for by a broad signal in the phosphomonoester region of solution ³¹P nuclear magnetic resonance (NMR) spectra. The molecular size range of this broad NMR signal and its molecular structure remain unclear. The aim of this study was to elucidate the chemical na...

The ability to identify the origin of phosphorus and understand processes controlling P cycling is essential for designing effective mitigation and restoration of eutrophic freshwater ecosystems. The oxygen isotope composition of orthophosphate (δ¹⁸Op) has significant potential as a tracer for P entering freshwater ecosystems. However, methods of a...

At the early stages of pedogenesis, the dynamics of phosphorus (P) in soils are controlled by microbial communities, the physicochemical properties of the soil and the environmental conditions. While various microorganisms involved in carrying out biogeochemical processes have been identified, little is known about the actual contribution of microb...

Phosphorus (P) fertilizers are known to increase crop productivity; however, when applied in excess, it can cause serious environment pollution. Monitoring P pollution in natural environments using stable isotopes has been difficult because P has only one stable isotope ( ³¹ P) making the use of P stable isotope tracing not an option. Radioactive P...

With an increasing number of researchers using the δ ¹⁸ O P method to investigate P cycling in the environment, it is necessary to conduct an inter-laboratory comparison study for the purification protocol as well as the measurement of silver phosphate with the TC/EA-IRMS like Watzinger et al. (2021) did. For the δ ¹⁸ O P method to progress, furthe...

Studies showed that the δ ¹⁸ O P is a useful tool to study P in the environment. Adequate extraction protocols for the targeted P pools of the study are a prerequisite for a successful study. Likewise, for most environmental samples, including water, soil, sediment and plant samples, it is crucial that the samples are processed as soon as possible...

Depending on the extract, it is necessary to modify the purification protocol slightly. Each sample is different and despite a thorough testing of the purification protocol, issues might occur. The three modifications suggested include (1) adjustments in pH, (2) magnesium ammonium phosphate (MAP) precipitation and (3) reductions, prior to A1, of ca...

The five stepwise purification of extracts and final precipitation of silver phosphate (A1–A5) are described. The first two steps (A1 and A2) are removing organic matter and are concentrating the phosphate in the extract by reducing the volume. Certain cations could interfere with the precipitation of silver phosphate and are removed in step A3. Si...

To plan a research study, one needs to (1) establish a research question, (2) make a set of observations, (3) form a hypothesis in an attempt to explain the observations and (4) test the hypothesis based on the data collected. The following questions should be addressed when designing a study including the analysis of δ ¹⁸ OP: (i) what is the resea...

Current understanding of phosphorus (P) dynamics is mostly based on experiments carried out under steady-state conditions. However, drying-rewetting is an inherent feature of soil behavior, and as such also impacts P cycling. While several studies have looked at net changes in P pool sizes with drying-rewetting, few studies have dynamically tracked...

At the early stages of pedogenesis, the dynamics of phosphorus (P) in soils are controlled by microbial communities, the physicochemical properties of the soil and the environmental conditions. While various microorganisms involved in carrying out biogeochemical processes have been identified, little is known about the actual contribution of microb...

The Atacama Desert (Chile) is one of driest places on Earth, with a hyper-arid climate and less than 2mm yr⁻¹ precipitation; nevertheless, it has experienced rare periods of sporadic rainfall. These periods shortly enhanced vegetation growth and microbial activity, which must have utilized major nutrients such as phosphorus (P). However, any biolog...

Rationale: A silver phosphate reference material (Ag3 PO4 ) for the measurement of the stable oxygen isotope compositions is much needed; however, it is not available from the authorities distributing reference materials. This study aims to fill this gap by calibrating a new Ag3 PO4 stable isotope comparison material produced by the University of...

Understanding P uptake in soil–plant systems requires suitable P tracers. The stable oxygen isotope ratio in phosphate (expressed as δ¹⁸OP) is an alternative to radioactive labelling, but the degree to which plants preserve the δ¹⁸OP value of the P source is unclear. We hypothesised that the source signal will be preserved in roots rather than shoo...

Soil phosphorus (P) remains an ever‐increasing topic of importance, notably for its key role as a nutrient for driving food production but with parallel concerns for damaging water quality, all against a backdrop of uncertainty of long‐term rock phosphate supplies. Soil is a key interface that holds P and regulates its onward flows to plants or lea...

Background and aims: Phosphorus (P) is an essential element for crop growth. However, while links of P turnover in soils to carbon (C) and nitrogen (N) availability have been described, it remains to be clarified how combinations of fertilizer C and N additions affect stocks and cycling of distinct P fractions at different soil depths. The objectiv...

Understanding the phosphate oxygen isotope (δ¹⁸O‐PO4) composition of bedrock phosphate sources is becoming ever more important, especially in areas of soil research which use this isotope signature as a proxy for biological cycling of phosphorus (P). For many of these studies, obtaining a sample of the source bedrock or applied mineral fertiliser f...

Dust deposition is an important source of phosphorus (P) to many ecosystems. However, there is little evidence of dust-derived P-containing minerals in soils. Here we studied P forms along a well-described climatic gradient on Hawaii, which is also a dust deposition gradient. Soil mineralogy and soil P forms from six sites along the climatic gradie...

Tree roots penetrate the soil to several meters depth, but the role of subsoils for the supply of nutrient elements such as phosphorus (P) to the trees is poorly understood. Here, we tested the hypothesis that increased P deficiency in the topsoil results in an increased microbial recycling of P from the forest subsoil. We sampled soils from four G...

While there are estimates of the abiotic processes contribution to soil phosphorus (P) availability, less is known about the contribution of biological processes. Two main enzymatic processes involved in soil P cycling are known to alter the oxygen isotopic composition of phosphate (δ¹⁸O-P), each in a different way, through the cleavage of the P–O...

Changes in the isotopic composition of oxygen associated with phosphate can provide information on the impact of phosphatase activity on soil P dynamics, whereas the use of radioactive P delivers information on P fluxes within soil systems. Although these two tracers may provide complementary data, they have rarely been used together to study soil...

Field data about the effect of soil pH on phosphorus (P) cycling is limited. A promising tool to study P cycling under field conditions is the ¹⁸O:¹⁶O ratio of phosphate (δ¹⁸OP). In this study we investigate whether the δ¹⁸OP can be used to elucidate the effect of soil pH on P cycling in grasslands. Soils and plants were sampled from different fert...

Quantification of turnover of inorganic soil phosphorus (P) pools is essential to improve our understanding of P cycling in soil–plant systems and improve representations of the P cycle in land surface models. Turnover can be quantified using mean residence time (MRT); however, to date there is little information on MRT of P in soil P pools. We int...

Abstract. The ability to identify the origin of phosphorus is essential to effectively mitigate eutrophication of freshwater ecosystems. The oxygen isotope composition of orthophosphate (δ¹⁸O_p) has been suggested to have a significant prospective as a tracer for P entering freshwater ecosystems. The δ¹⁸O_p...

Quantification of turnover of inorganic soil phosphorus (P) pools is essential to improve our understanding of P cycling in soil-plant systems at different spatial scales. Turnover can be quantified using mean residence time (MRT), however, 15 to date there is little information on MRT of P in soil P pools. We introduce an approach to quantify MRT...

Belowground (BG) plant resource allocation, including roots and rhizodeposition, is a major source of soil organic matter. Knowledge on the amounts and turnover of BG carbon (C), nitrogen (N), and phosphorus (P) in soil is critical to the understanding of how these elements cycle in soil-plant system. However, the assumptions underlying the quantif...

Current understanding of phosphorus (P) cycling in soils can be enhanced by integrating previously discrete findings concerning P speciation, exchange kinetics, and the underlying biological and geochemical processes. Here, we combine sequential extraction with P K-edge X-ray absorption spectroscopy and isotopic methods (33 P and 18 O in phosphate)...

The isotopic composition of oxygen bound to phosphorus (P) in phosphate (δ¹⁸O‐P) has been used to improve our understanding of P cycling in the soil–plant system. The determination of δ¹⁸O‐P in the inorganic (Pi) and organic (Po) soil P pools obtained from soil sequential extractions would further our knowledge. Although methods exist for the purif...

Understanding the mechanisms underlying phosphorus (P) availability is important to predict forest productivity in a changing environment. We quantified P fluxes and traced P from plant litter into inorganic and organic soil P pools in organic horizons from two contrasting temperate forest soils with low and high inorganic P availability, respectiv...

Background The dynamics of phosphorus (P) in the environment is important for regulating nutrient cycles in natural and managed ecosystems and an integral part in assessing biological resilience against environmental change. Organic P (Po) compounds play key roles in biological and ecosystems function in the terrestrial environment being critical t...

The article “Organic phosphorus in the terrestrial environment: a perspective on the state of the art and future priorities”, written by Timothy S George et al., was originally published with incorrect affiliation information for one of the co-authors, E. Klumpp.

Forest clear-cuts may have severe effects on the soil structure and related nutrient cycling, though with yet unknown consequences for nutrient pools such as phosphorus (P) within microaggregates. We sampled the bulk mineral topsoil prior to clear cut as well as 1 and 2 years thereafter from the experimental forest site Wüstebach, Germany, and we a...

Arable subsoils store large amounts of phosphorus (P); however, it is unclear to what extent, and under which conditions, subsoil resources might supplement crop P acquisition. Here, we hypothesized that (i) insufficient supply of P in topsoil promotes P acquisition from subsoil and (ii) subsoil P cycling is regulated by nitrogen (N) supply. We sam...

Background Changing the phosphorus (P) nutrition leads to changes in plant metabolism. The aim of this study was to investigate how these changes are reflected in the distribution of 33P and the isotopic composition of oxygen associated to P (δ18OP) in different plant parts of soybean (Glycine max cv. Toliman). Two P pools were extracted sequential...

Biopores are characterised by high concentrations of plant available nutrients and provide preferential pathways for root growth into the subsoil, thereby potentially enabling plants to access phosphorus (P) resources located in the subsoil. Here, we sampled biopores from a replicated agricultural field trial in Klein-Altendorf, Germany, to analyse...

In this study, we conduct a spatial analysis of soil total phosphorus (TP), acid extractable phosphate (PO4) and the stable oxygen (O) isotope ratio within the PO4 molecule (δ18OPO4) from an intensively managed agricultural grassland site. Total P in the soil was found to range from 736 to 1952mgPkg−1, of which between 12 and 48% was extractable us...

An essential aspect of eutrophication studies is to trace the ultimate origin of phosphate ions (P-PO4) associated with the solid phase of river sediments, as certain processes can make these ions available for algae. However, this is not a straightforward task because of the diversity of allochthonous and autochthonous sources that can supply P-PO...

Pyrophosphatases (EC 3.6.1.1) are ubiquitous enzymes that catalyse the hydrolysis of pyrophosphate, a byproduct of many biochemical reactions. The hydrolysis leads to an oxygen isotope exchange between the newly formed phosphate molecules and water. Here, we applied Raman spectroscopy to monitor the oxygen isotope exchange reaction in presence of p...

This chapter addresses the following questions: (i) is phosphorus (P) that passes through the “organic pathway”, i.e. that is found at some point in time in an organic form or within soil organisms or plant residues completely used by plants (100 % use by plants) and (ii) does P that passes through the “organic pathway” fully remain in the soil/pla...

The identification and quantification of different soil organic phosphorus (P) compounds is crucial for a better understanding of soil P dynamics. The aim of this study was to compare two commonly used characterisation methods: 31P NMR spectroscopy and enzyme addition assays (EAAs). The same 0.25 M NaOH and 0.05 M ethylenediaminetetraacetic acid (E...

Stoichiometric approaches have been applied to understand the relationship between soil organic matter dynamics and biological nutrient transformations. However, very few studies explicitly considered the effects of agricultural management practices on soil C : N : P ratio. The aim of this study was to assess how different input types and rates wou...

Phosphorus (P) is an essential nutrient for living organisms. Under P-limiting conditions plants and microorganisms can exude extracellular phosphatases that release inorganic phosphate (Pi) from organic phosphorus compounds (Porg). Phytic acid (myo-inositol hexakisphosphate, IP6) is an important form of Porg in many soils. The enzymatic hydrolysis...

Phosphorus (P) is an essential nutrient for living organisms. Under P-limiting conditions plants and microorganisms can exude extracellular phosphatases that release inorganic phosphate (Pi) from organic phosphorus compounds (Porg). Phytic acid (myo-inositol hexakisphosphate, IP6) is an important form of Porg in many soils. The enzymatic hydrolysis...

Urine contains about 50 % of the phosphorus (P) and about 90 % of the nitrogen (N) excreted by humans and is therefore an interesting substrate for nutrient recovery. Source-separated urine can be used to precipitate struvite or, through a newly developed technology, nitrified urine fertilizer (NUF). In this study, we prepared 33P radioisotope- and...

Phosphorus is a major nutrient for all living organisms. In the terrestrial environment, P is considered a double-edged sword. In some areas, agricultural production is strongly limited by the low soil P availability, while in others, P inputs in excess of plant needs have resulted in pollution of water bodies. A better understanding of soil-plant...

Plants and microorganisms under phosphorus (P) stress release extracellular phosphatases as a strategy to acquire inorganic phosphate (Pi). These enzymes catalyze the hydrolysis of phosphoesters leading to a release of Pi. During the enzymatic hydrolysis an isotopic fractionation (ε) occurs leaving an imprint on the oxygen isotope composition of th...

Cette étude fait le point sur un ensemble de travaux réalisés pour développer une méthode d'extraction et de purification des phosphates à partir de matrices sédimentaires en vue d'une analyse de la composition isotopique de leurs atomes d'oxygène. La méthode choisie parmi les quelques procédures proposées par la littérature est décrite en détail a...

The growing human population and urbanization result in greater phosphorus (P) fluxes from the agro-ecosystems to consumers and into the waste water. Various technologies to recover the finite P resource from these waste streams are available. Urine contains about 50% of P excreted by humans. If collected separately, struvite (MgNH 4 PO 4 ·6H 2 O)...

The objective of this study was to investigate the isotopic composition of oxygen bound to phosphate (δ ¹⁸ O ‐ PO 4 ) in different phosphorus ( P ) pools in plant leaves. As a model plant we used soybean ( G lycine max cv Toliman) grown in the presence of ample P in hydroponic cultures. The leaf blades were extracted with 0.3 M trichloroacetic acid...

IsoPhos 2012: Development of Isotopic Tracers for a Better Understandingof the Phosphorus Cycle;Monte Verità, Switzerland, 24-29 June 2012 IsoPhos 2012, a conference dedicated to cutting-edge research on phosphorus, was held in the Centro Stefano Franscini of the Swiss Federal Institute of Technology of Zurich (ETH Zurich). It gathered 63 scientist...