Strategy for characterization of distribution and associations of organobromine compounds in soil using synchrotron radiation based spectromicroscopies.

It is imperative to obtain information on the binding sites and distribution of organic contaminants in soils in order to understand their reactions and fates in soils. Here we propose a novel strategy that enables in situ observation at the micrometer scale of the spatial distribution of organobromine compounds and characterization of their associations with organic carbon (OC) forms (i.e., C-functional groups) in soils. According to the strategy, two complementary synchrotron radiation-based spectroscopic techniques (i.e., Fourier transform-infrared (FT-IR) and micro X-ray fluorescence (μ-XRF) spectromicroscopies) were applied to characterize the binding sites and distribution of Br (as a conservative tracer for organobromine compounds), OC forms, clay minerals, and other mineral elements within soil particles, respectively, at a 6-10 μm-scale spatial resolution. This study is the first in situ investigation on the microscale locations of organobromine compounds at environmental levels and their associations with OC forms and clay mineral/elements in natural soils. The strategy paves the way toward in situ characterization of the distribution, speciation, and binding sites of some organic contaminants, which is critical in understanding their associated environmental processes in soils.