Incorporation of heavy metals by the mud snail, Cipangopaludina chinensis malleata Reeve, in submerged paddy soil treated with composted sewage sludge

The biomass of newborn snails was higher in paddy soil without rice plants than in the soil with rice plants. There was an inverse correlation between shell width and concentratins of Zn and Cu in snail flesh. The Zn and Cu concentrations in snail flesh were extremely high compared with those in the paddy soil surrounding the snails, possibly because snails ingest sludge, one of the main components of the composts. These results suggest that this type of snail may be used to eliminate Zn and Cu from paddy soil when composted sewage sludge has been applied.