Correlations between As in earthworms’ coelomic fluids and As bioavailability in highly polluted soils as revealed by combined laboratory X-ray techniques

Combined X-ray-based spectroscopy techniques were applied to investigate arsenic (As) bioaccumulation in earthworms (Eisenia andrei) exposed to six field-collected polluted soils (58–13 330 mg As kg–1). After 14 days of exposure to the arsenious soils, the As distribution in earthworms was examined by micro-X-ray fluorescence spectroscopy (μ-XRF), after epoxy resin embedding and preparing thin sections. Similar to μ-XRF data, XRF-computed tomography (XRF-CT) confirmed As accumulation in the coelom of intact earthworms. Therefore, total-reflection XRF was used to determine total As within both the whole earthworm’s body (AsE) and coelomic fluid extracts (AsF). Bioaccumulation data (AsE and AsF) were thereafter evaluated in relation to total As concentration in soils (AsT) and to As mobile fraction in soils. A significant linear correlation (R2 = 0.97) was found between AsE and AsF, indicating that the As sequestrated into the coelomic fluid may reflect the total body concentration. Therefore, we may conclu...