Use of Phosphate Oxygen Isotopes for Identifying Atmospheric-P Sources: A Case Study at Lake Kinneret

Abstract

The input of phosphorus (P) through atmospheric deposition can be a major source of P to fresh water bodies and may strongly affect their biogeochemistry. In Lake Kinneret (LK), northern Israel, dust deposition provides a significant fraction of the bioavailable P input. Here, we demonstrate that the oxygen isotopic composition of resin-extractable inorganic phosphate (δ(18)OP) in dust particles can be used to identify the phosphate source. Samples of soils with both natural vegetation and agricultural cover were collected upwind of LK and found to have distinct δ(18)OP value ranges (17.4-18.2‰ and 19.3-22.1‰, respectively). The δ(18)OP values for dust, collected continuously over LK during June 2011 to March 2012, were in the same range as agricultural soils. The dust concentration in the air decreased from the dry to the wet season and was correlated with a decrease in P concentration in air, yet no correlation was found between these parameters and dust δ(18)OP. Dust deposited during short-term desert dust events was characterized by a combination of high δ(18)OP values ranging from 22.2‰ to 22.7‰ and high concentrations of dust in the air. The data we present demonstrates a new application of δ(18)OP measurements for direct estimation of dust-P sources to lakes, as well as the potential for tracing dust-P on larger scales.

Oxygen isotope ratios of plant available phosphate in lowland tropical forest soils

“…O P values reflect a movement towards isotopic equilibrium with soil water, as was reported for the resin-P pool in a series of natural extra tropical soils (Zohar et al, 2010;Angert et al, 2011Angert et al, , 2012Tamburini et al, 2012;Gross et al, 2013;Gross and Angert, 2015).…”

“…18 O P values in isotopic equilibrium with soil water (Zohar et al, 2010;Angert et al, 2011Angert et al, , 2012Tamburini et al, 2012;Gross et al, 2013;Gross and Angert, 2015). The authors of these studies hypothesized that the close to equilibrium d We suggest the above equilibrium values we found in our study reflect a dynamic balance between two microbial processes: 1) the efflux of cell internal inorganic phosphate back to the soil surroundings and 2) the uptake of phosphate molecules by the microbial biomass.…”

“…The aim of this project was to derive information on the processes that control phosphate cycling in tropical forest soils, based on natural variation in the isotopic composition of oxygen in soil phosphate (d 18 O P ). This Technique has provided valuable information on soil P dynamics in different ecosystems worldwide (Zohar et al, 2010;Angert et al, 2011Angert et al, , 2012Tamburini et al, 2012;Gross et al, 2013;Gross and Angert, 2015), but has not so far been applied in tropical soils. We took advantage of two long-term and well-studied field experiments in lowland tropical forest in Panama: an experiment initiated in 1998 involving factorial P, nitrogen (N) and potassium (K) additions Yavitt et al, 2011;Sayer et al, 2012;Mirabello et al, 2013;Schreeg et al, 2013;Turner and Wright, 2014), and a second experiment initiated in 2003 at the same site involving litter manipulation (removal and addition) (Sayer and Tanner, 2010;Vincent et al, 2010;Sayer et al, 2012).…”

Oxygen Isotopes for Unraveling Phosphorus Transformations in the Soil-Plant System: A Review

“…Dust-borne P (phosphate sorbed on particles and brought by aeolian material) can constitute an important source of P to terrestrial and aquatic ecosystems (Okin et al, 2004), and d 18 O-P has been used to trace atmospheric P inputs to Lake Kinneret in Israel (Gross et al, 2013). Gross et al (2013) sampled several P sources around Lake Kinneret and compared their resin-extracted d 18 O-P with that extracted from dust samples collected close to the lakeshores.…”

The oxygen isotope composition of phosphate released from phytic acid by the activity of wheat and <i>Aspergillus niger</i> phytase

“…In the terrestrial environment, the oxygen isotope composition (δ 18 O) of phosphate has been used as a tracer in the terrestrial environment to study the cycling of P in soils (Zohar et al, 2010a and b;Tamburini et al, 2010Tamburini et al, , 2012Angert et al, 2011Angert et al, , 2012Gross and Angert, 2015), in plants (Young et al, 2009;Pfahler et al, 2013) and in aerosols (Gross et al, 2013). Under ambient conditions and in the absence of biological activity, the δ 18 O of phosphate does not change (Kolodny et al, 1983;O'Neil et al, 2003).…”