The dissolved concentrations for some heavy metals (e.g., Cu,
Zn, and Ni) were two to ten times higher than those previously
observed in 1992 since the early stage of HSP operation
[24], indicating the deterioration of heavy metal pollution. However,
the concentrations of the analyzed heavy metals mostly fell
within national water quality and soil regulation standards, with
dissolved Mn at IZ as the only exception; however, there were several
particulate and sedimentary metals, such as Ag, Zn, Cu, As,
and Ni, which were found at concentrations close to or higher
than the SQGs at certain or even all stations (Tables 1 and 2)