Based on long-term monitoring data of typical surface
water from
1999 to 2016, this study evaluated the temporal, spatial, and source
changes of seven trace metals. The results show that average concentrations
of trace metals were Zn (248.61 μg L–1) ≫
Mn (74.27 μg L–1) > Ba (72.4 6 μg
L–1) > Al (44.11 μg L–1) > As
(6.36 μg L–1) > Ni (3.29 μg L–1) > Cd (2.98 μg L–1). There
is a decreasing
trend in the concentrations of Al, Cd, Mn, Ni, and Zn. Pollution levels
in the midstream are relatively higher than in the upstream and downstream.
A wavelet analysis suggested that the Al and As contamination levels
exhibited clear periodic oscillations. According to the source apportionment
analysis, the pollution sources of A, B, and C periods were determined,
among which historical mining, industrial, agricultural, and geological
natural sources were the main contributors. Anthropogenic pollution
sources during stage B accounted for the largest proportion, reaching
76.54%. Historical mining source emissions remained relatively stable
(43.17, 34.99, and 40.83%), but the proportion remained at the highest
level. The health risk assessment shows that there is no obvious health
risk, and As and Cd have certain cancer risk.