Speed-mapping of arsenic distribution in the tissues of earthworms inhabiting arsenious soil.



We have examined the distribution of arsenic in the metal-sequestering chloragogenous tissue of a population of the earthworm, Lumbricus rubellus, exposed to the metalloid in its natural environment. The localization technique was qualitative digital X-ray speed mapping (2 minute total acquisition time) of fresh air dried tissue smears. Arsenic was located in association with sulphur in a discrete chloragocytic compartment; it was not detected in the phosphate-rich chloragosome granules. In earthworm tissues arsenic was distributed according to its sulphydryl-seeking trivalent form, not as the phosphate-resembling pentavalent form.