Title: Opportunities for Soil and Plant Scientists at the Sirius-LNLS CARNAÚBA Beamline
Optimal performance of soil-plant systems is essential for high agricultural productivity and conservation of natural ecosystems. The element specificity of synchrotron X-ray techniques provides unprecedented mechanistic information about chemical and structural properties of soils and plants, which serves as a foundation for improved strategies for managing natural resources. The CARNAÚBA beamline is designed with unique and complementary analytical capabilities of that are well suited for studying soils, plants, and soil-plant interfaces. Soils themselves comprise complex assemblages of minerals, organic matter, non-crystalline inorganic solids and microorganisms; and plant roots alter the chemical and microbial properties of the root-soil interface, i.e., the rhizosphere. Functional insights to such complex, multi-component systems are enhanced by characterization of the same sample areas with multiple, spatially resolved analytical techniques. For multi-element imaging, the two experimental stations at CARNAÚBA with different beam spot sizes will facilitate rapid imaging of larger sample areas or volumes to define overall spatial patterns of chemical elements, followed by high-resolution imaging of chemical substructure on features of interest using a smaller beam (down to 30 nm). Moreover, heterogeneous spatial patterns of chemical elements in soils and at soil-root interfaces enhances identification of less abundant chemical species of a given element by micro- or nano-scale X-ray absorption spectroscopy (µ-XAS, n-XAS). Similarly, in plant sciences, access to X-ray beams of multiple spot sizes at a single beamline will enable rapid and high-resolution imaging of important biological elements at tissue, cellular, and sub-cellular levels. The CARNAÚBA beamline also covers a broad energy range from tender to hard X-rays. Soils contain numerous chemical elements. Ideally, all elements of concern to a particular problem could be imaged simultaneously to augment chemical speciation analysis via knowledge of element co-localization. At low-energies, the more abundant soil matrix elements (silicon and aluminum) can be imaged along with important plant nutrients – especially phosphorus, sulfur, potassium, and calcium. Remarkably, the beamline is also designed for imaging and spectroscopy of heavier soil-matrix elements and biological micronutrients (e.g., iron, manganese, zinc, copper, selenium), and toxic metal(loids) of environmental concern in soils, water, and the food chain (e.g., arsenic, mercury, cadmium and lead). Finally, spatially resolved diffraction should identify mineral phases at matrix contents far below those needed for detection by bulk-sample diffraction. The CARNAÚBA beamline will provide complementary X-ray techniques that are of great value for addressing a broad range of problems in soil and plant sciences.