observation of localized, sub-mm scale changes of phosphorus biogeochemistry in the rhizosphere.

Aims: We imaged the sub-mm distribution of labile P and pH in the rhizosphere of three plant species to localize zones and hot spots of P depletion and accumulation along individual root axes and to relate our findings to nutrient acquisition / root exudation strategies in P-limited conditions at different soil pH, and to mobilization pattern of other elements (Al, Fe, Ca, Mg, Mn) in the rhizosphere.

Methods: Sub-mm distributions of labile elemental patterns were sampled using diffusive gradients in thin films and analysed using laser ablation inductively coupled plasma mass spectrometry. pH images were taken using planar optodes.

Spatiotemporal dynamics of phosphorus release, oxygen consumption and greenhouse gas emissions after localised soil amendment with organic fertilisers.

Organic fertilisation inevitably leads to heterogeneous distribution of organic matter and nutrients in soil, i.e. due to uneven surface spreading or inhomogeneous incorporation.

Two decades of chemical imaging of solutes in sediments and soils--a review.

The increasing appreciation of the small-scale (sub-mm) heterogeneity of biogeochemical processes in sediments, wetlands and soils has led to the development of several methods for high-resolution two-dimensional imaging of solute distribution in porewaters. Over the past decades, localised sampling of solutes (diffusive equilibration in thin films, diffusive gradients in thin films) followed by planar luminescent sensors (planar optodes) have been used as analytical tools for studies on solute distribution and dynamics. These approaches have provided new conceptual and quantitative understanding of biogeochemical processes regulating the distribution of key elements and solutes including O2, CO2, pH, redox conditions as well as nutrient and contaminant ion species in structurally complex soils and sediments.

Numerical evaluation of lateral diffusion inside diffusive gradients in thin films samplers.

Using numerical simulation of diffusion inside diffusive gradients in thin films (DGT) samplers, we show that the effect of lateral diffusion inside the sampler on the solute flux into the sampler is a nonlinear function of the diffusion layer thickness and the physical sampling window size. In contrast, earlier work concluded that this effect was constant irrespective of parameters of the sampler geometry. The flux increase caused by lateral diffusion inside the sampler was determined to be ∼8.

Phosphorus uptake by L. is quantitatively predicted by infinite sink extraction of soil P.

Background And Aims: Sink extraction of phosphorus from soils has been utilised to study soil P desorption kinetics and as index of plant availability, but not for quantitative prediction of P uptake by plants. Here we investigate the potential of a modified sink extraction method for determining P desorption kinetics and for quantifying plant available soil P.

Methods: Modified diffusive gradients in thin films samplers were immersed in shaken soil suspensions for long-term extraction of soil P.

Uncertainty evaluation of the diffusive gradients in thin films technique.

Although the analytical performance of the diffusive gradients in thin films (DGT) technique is well investigated, there is no systematic analysis of the DGT measurement uncertainty and its sources. In this study we determine the uncertainties of bulk DGT measurements (not considering labile complexes) and of DGT-based chemical imaging using laser ablation - inductively coupled plasma mass spectrometry. We show that under well-controlled experimental conditions the relative combined uncertainties of bulk DGT measurements are ∼10% at a confidence interval of 95%.

Gel for simultaneous chemical imaging of anionic and cationic solutes using diffusive gradients in thin films.

We report on a novel gel based on diffusive gradients in thin films (DGT) for the simultaneous measurement of cations and anions and its suitability for high resolution chemical imaging by using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). The new high resolution mixed binding gel (HR-MBG) is based on zirconium-hydroxide and suspended particulate reagent-iminodiacetate (SPR-IDA) as resin materials which are embedded in an ether-based urethane polymer hydrogel. The use of this polymer hydrogel material allows the production of ultrathin, highly stable and tear-proof resin gel layers with superior handling properties compared to existing ultrathin polyacrylamide gels.