Higher throughput and enhanced sensitivity in synchrotron biogeochemistry

Enzo Lombi^a, P. Wang^b and P.M. Kopittke^c

^a Future Industries Institute, University of South Australia, Australia

^b College of Resources and Environmental Sciences, Nanjing Agricultural University, China

^c School of Agriculture and Food Sciences, The University of Queensland, Australia

enzo.lombi@unisa.edu.au

A number of synchrotron-based techniques are increasingly being used to investigate nutrients and contaminant metals in a variety of environmental samples. The advantages of these techniques are well known: minimal sample preparation (e.g. reduce risk of artefacts), high lateral and spatial resolution, ability to probe the speciation of elements in situ. However, until recently, synchrotron techniques have been considered generally ‘slow’ and not particularly sensitive in comparison with other methods providing very detailed information on a few samples at reasonably high concentrations. This has changed. The advent of fast and sensitive detector technologies has completely transformed the way we approach synchrotron experiments and the information we can obtain. For instance, traditionally, X-ray Fluorescence (XRF) elemental mapping has been used to gain an understanding of metal distribution while X-ray Absorption Spectroscopy (XAS) has been employed to investigate metal speciation. This latter approach has been performed at both the ‘bulk’ and microscale; these two approaches being complementary and providing different information. However, in the last few years, the development of a new generation of fast fluorescence detectors providing unprecedented rates of data acquisitions is blurring the divide between imaging and speciation techniques due to the developments of methods such as XANES-imaging (X-Ray Absorption Near Edge-imaging). Furthermore, fast detectors have allowed us to probe not just larger samples and more samples, they have also decreased the risk of beam damage and in-vivo, time series experiments are now possible. At the same time, the development of ever more sensitive detectors and higher fluxes have enabled the analyses of trace element distribution and speciation at concentrations that are environmentally relevant. In this presentation we will discuss how new technologies have changed the information we can obtain from synchrotron experiments, how their design has changed over time and will also briefly discuss what fourth-generation synchrotron sources will enable us to do.