Apple snails and their endosymbionts bioconcentrate heavy metals and uranium from contaminated drinking water

VEGA, I.A.; ARRIBERE, M.; ALMONACID, A; RIBEIRO GUEVARA,S; ALFREDO JUAN CASTRO VAZQUEZ

ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH

SPRINGER HEIDELBERG

Lugar: HEIDELBERG; Año: 2011

0944-1344

Purpose: The differential ability of apple snail tissues, endosymbionts and eggs tobioaccumulate several metals (Sb, As, Ba, Br, Zn, Cr, Fe, Hg, Se) and U wasinvestigated. Methods: Metal concentrations were determined by neutron activationanalysis in several tissues, endosymbionts and eggs from mature apple snails culturedin either tap water or reconstituted water (prepared with ASTM type I water). Results:The highest bioconcentration factors (BCFs) in the midgut gland were found for Ba, Zn,As, Se, U, Br and Hg (in decreasing order), while the highest in the kidney were for Ba,Br and Hg. The foot showed the highest BCFs for Ba, Hg, Br and Se (in decreasingorder). Calcified tissues (uterus, shell) and eggs showed low BCFs, except for Ba.BCFs for most elements were significantly higher in endosymbionts isolated frommidgut gland tissue than in whole gland tissue. The concentration of most of thestudied elements dropped significantly in tissues and endosymbionts obtained fromsnails cultured in reconstituted water instead of tap water. Snails cultured inreconstituted water and then exposed or not to Hg, As and U (at the MaximumContaminant Level -MCL- allowed by the US´ Environmental Protection Agency) alsoresulted in high levels accumulated in midgut gland, endosymbionts and kidney.Conclusions: Our findings show that this symbiotic association can be a usefulbioindicator of metal pollution in freshwater bodies and that the unrestricted use ofampullariid snails as human and animal food must be considered with caution.