Leachability of elements in alkaline and acidic coal fly ash samples during batch and column leaching tests

► Both acidic and alkaline fly ash samples contain environmentally available elements. ► Acidic fly ash samples are relatively richer in trace elements. ► Significant proportions of several elements were leached from fly ash samples by DDI water and acid rain. ► Older unlined fly ash disposal sites could pose environmental risk of contamination. ► Effective containment methods are desirable for unlined/leaky disposal facilities.