The potential environmental hazards posed by trace elements have assumed serious proportions
due to their toxicity, bioavailability and geochemical behavior. The toxicity and
mobility of trace elements in coal gangue is dependent on the elements' chemical properties,
therefore, the quantification of the different forms of trace elements is more significant
than the estimation of their total concentrations. In this study, the mobility behavior
of trace elements in coal gangue from the Huainan Coalfield was studied to evaluate
the potential eco-toxicity of the trace elements. Sequential extraction was employed
to analyze the fractionation behavior of trace elements in coal gangue. The selected
trace elements (As, Co, Cr, Cu, Mn, Ni, Se, Sn, V and Zn) are predominantly found
in silicate-bound, sulfide-bound and carbonate-bound fractions. The correlation of
the element concentration with ash yield, aluminum, calcium and iron-sulfur indicates
that As, Co, Cu, Ni, Se and Zn in coal gangue are mainly associated with sulfide minerals,
which could release from coal gangue easily and can disperse into the environment
as a result of long-term natural weathering. The Risk Assessment Code reveals that
the trace elements (Mn, Cr, Se, Ni, Zn, As and Cu) can pose serious environmental
risks to the ecosystem. The fractionation profiles of other elements (Co, Sn and V)
indicate no risk or low risk to the environment.